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milton smith milton smith american computer security application developer researcher writer smith best known role leading java platform security oracle period high-profile security incidents fall 2012 due climate around java security 2013 smith invited present black hat leadership closed session non-disclosure agreement top industry leaders year smith established first ever full security track software developers conference javaone oracle premier conference java software developers san francisco california usa smith continues principal security analyst oracle working strategically across company business units smith active collaborator industry developing open source security tools researchers well participating security conference events organizing period smith chief technical editor application security book project colleges prior oracle around june 2011 smith leading security user data analytics uda business unit yahoo developed innovative security controls secure yahoo click stream revenues smith also lead yahoo enterprise security triage program monitoring enterprise vulnerabilities tracking remediation activities owasp one largest non-profit organizations security practitioners world march 12 2015 smith developed deepviolet tls/ssl scanning api researchers use extend tls/ssl scanning projects today deepviolet owasp incubator project smith also leader owasp security logging api project open source project extending important security features applications use popular logging platforms like log4j logback
Computer security
dns hijacking dns hijacking dns redirection practice subverting resolution domain name system dns queries achieved malware overrides computer tcp/ip configuration point rogue dns server control attacker modifying behaviour trusted dns server comply internet standards modifications may made malicious purposes phishing self-serving purposes internet service providers isps public/router-based online dns server providers direct users web traffic isp web servers advertisements served statistics collected purposes isp dns service providers block access selected domains form censorship one functions dns server translate domain name ip address applications need connect internet resource website functionality defined various formal internet standards define protocol considerable detail dns servers implicitly trusted internet-facing computers users correctly resolve names actual addresses registered owners internet domain rogue dns server translates domain names desirable websites search engines banks brokers etc ip addresses sites unintended content even malicious websites users depend dns servers automatically assigned isps zombie computers use dns-changing trojans invisibly switch automatic dns server assignment isp manual dns server assignment rogue dns servers router assigned dns servers also altered remote exploitation vulnerability within router firmware users try visit websites instead sent bogus website attack termed pharming site redirected malicious website masquerading legitimate website order fraudulently obtain sensitive information termed phishing number consumer isps cablevision optimum online centurylink cox communications rcn rogers charter communications spectrum plusnet verizon sprint t-mobile us virgin media frontier communications bell sympatico t-online optus mediacom ono talktalk bigpond telstra ttnet türksat telkom indonesia use dns hijacking purposes displaying advertisements collecting statistics dutch isps xs4all ziggo use dns hijacking court order ordered block access pirate bay display warning page instead practices violate rfc standard dns nxdomain responses potentially open users cross-site scripting attacks concern dns hijacking involves hijacking nxdomain response internet intranet applications rely nxdomain response describe condition dns entry specified host one query invalid domain name example www.example.invalid one get nxdomain response – informing application name invalid taking appropriate action example displaying error attempting connect server however domain name queried one non-compliant isps one would always receive fake ip address belonging isp web browser behavior annoying offensive connections ip address display isp redirect page provider sometimes advertising instead proper error message however applications rely nxdomain error instead attempt initiate connections spoofed ip address potentially exposing sensitive information examples functionality breaks isp hijacks dns cases isps provide subscriber-configurable settings disable hijacking nxdomain responses correctly implemented setting reverts dns standard behavior isps however instead use web browser cookie store preference case underlying behavior resolved dns queries continue redirected isp redirect page replaced counterfeit dns error page applications web-browsers opted scheme using cookies opt-out targets http protocol scheme actually implemented protocol-neutral dns system uk information commissioner office acknowledged practice involuntary dns hijacking contravenes pecr ec directive 95/46 data protection require explicit consent processing communication traffic however refused intervene claiming would sensible enforce law would cause significant indeed demonstrable detriment individuals germany 2019 revealed deutsche telekom ag manipulated dns servers also transmitted network traffic non-secure cookies users use https third party company web portal t-online users redirected due dns manipulation owned deutsche telekom user filed criminal complaint deutsche telekom stopped dns manipulations icann international body responsible administering top-level domain names published memorandum highlighting concerns affirming end users dissatisfied poor opt-out options like cookies responded controversy finding ways avoid spoofed nxdomain responses dns software bind dnsmasq offer options filter results run gateway router protect entire network google among others run open dns servers currently return spoofed results user could use google public dns instead isp dns servers willing accept use service google privacy policy potentially exposed another method google track user one limitation approach providers block rewrite outside dns requests opendns owned cisco similar popular service alter nxdomain responses google april 2016 launched dns-over-https service scheme overcome limitations legacy dns protocol performs remote dnssec check transfers results secure https tunnel also application-level work-arounds noredirect firefox extension mitigate behavior approach like fixes one application example firefox address issues caused website owners may able fool hijackers using certain dns settings example setting txt record unused wildcard address e.g *.example.com alternatively try setting cname wildcard example.invalid making use fact '.invalid guaranteed exist per rfc limitation approach prevents hijacking particular domains may address vpn security issues caused dns hijacking
Computer security
isp redirect page isp redirect page spoof page served major isps including cox communications embarq verizon rogers earthlink various others world wide web users enter invalid dns name user types incorrect uniform resource locator url example codice_1 instead codice_2 isp dns server respond spoofed dns response redirects user advertising web page domain name system dns resolution process translating human-readable domain name example codice_3 ip address computers use every isp runs dns server allow customers translate domain names ip addresses computers understand use isp dns server receives request translate name according rfc dns server return associated ip address customer computer able connect requested resource isp dns server receives request name recognized unavailable isps spoof nx null response instead return ip address search advertising page client client using web browser display search page contains possible suggestions proper address small explanation error search pages often contain advertising paid isp sometimes customer opt-out service opt-out frequently implemented layer spoofing opt-out procedures vary isp isp method implementation effectiveness
Computer security
simple symmetric transport protocol simple symmetric transport protocol sstp protocol delivering messages clients servers used microsoft groove
Internet protocols
list programming language researchers following list researchers programming language theory design implementation related areas
Programming language topics
qoriq qoriq brand arm-based power isa-based communications microprocessors nxp semiconductors formerly freescale evolutionary step powerquicc platform initial products built around one e500mc cores came five different product platforms p1 p2 p3 p4 p5 segmented performance functionality platform keeps software compatibility older powerpc products powerquicc platform 2012 freescale announced arm based qoriq offerings beginning 2013 qoriq brand p1 p2 p4 product families announced june 2008 details p3 p5 products announced 2010 qoriq p series processors manufactured 45 nm fabrication process available end 2008 p1 p2 mid-2009 p4 2010 p5 qoriq series based 28 nm process pushing aggressive power envelope target capping 30 w. using e6500 core altivec expected shipping 2013 qoriq ls-1 ls-2 families arm based processors using cortex a7 cortex a9 a15 a53 a72 cores upon isa agnostic layerscape architecture available since 2013 target low mid range networking wireless infrastructure applications layerscape ls architecture latest evolution qoriq family features previously provided dpaa like compression may implemented software hardware depending specific chip transparent application programmers ls-1 ls-2 announced use cortex a7 a9 a15 a53 a72 cores initial ls-1 series include accelerated packet processing layer focusing typical power consumption less 3w using two cortex a7 providing ecc caches ddr3/4 1000 1600 mt/s dual pci express controllers x1/x2/x4 operation sd/mmc sata 1/2/3 usb 2/3 integrated phy virtualized etsec gigabit ethernet controllers ls1 means ls1xxx series e.g. ls1021a etc ls2 means ls2xxx series ls2 means higher performance level ls1 indicate second generation middle two digits product name core count last digit distinguishes models cases higher digit meaning greater performance “ ” end indicates arm processor lx designates 16 nm finfet generation ls1 family built layerscape architecture programmable data-plane engine networking architecture ls1 ls2 families processors offer advanced high-performance datapath network peripheral interfaces features frequently required networking telecom/datacom wireless infrastructure military aerospace applications freescale semiconductor inc. acquired nxp semiconductors late 2015 announced network processor system architecture said give flexibility scalability required network infrastructure oems handle market trends connected devices massive datasets tight security real-time service increasingly unpredictable network traffic patterns qoriq p series processors based e500 e5500 cores p10xx series p2010 p2020 based e500v2 core p204x p30xx p40xx e500mc core p50xx e5500 core features include 32/32 kb data/instruction l1 cache 36-bit physical memory addressing appended top virtual address process context process still 32bit double precision floating point unit present cores support virtualization hypervisor layer present products featuring e500mc e5500 dual multi-core devices supports symmetric asymmetric multiprocessing run multiple operating systems parallel p1 series tailored gateways ethernet switches wireless lan access points general-purpose control applications entry level platform ranging 400 800 mhz devices designed replace powerquicc ii pro powerquicc iii platforms chips include among integrated functionality gigabit ethernet controllers two usb 2.0 controllers security engine 32-bit ddr2 ddr3 memory controller ecc support dual four-channel dma controllers sd/mmc host controller high speed interfaces configured serdes lanes pcie sgmii interfaces chip packaged 689-pin packages pin compatible p2 family processors p2 series designed wide variety applications networking telecom military industrial markets available special high quality parts junction tolerances −40 125 °c especially suited demanding doors environments mid-level platform devices ranging 800 mhz 1.2 ghz designed replace powerquicc ii pro powerquicc iii platforms chips include among integrated functionality 512 kb l2 cache security engine three gigabit ethernet controllers usb 2.0 controller 64-bit ddr2 ddr3 memory controller ecc support dual four-channel dma controllers sd/mmc host controller high speed serdes lanes configured three pcie interfaces two rapidio interfaces two sgmii interfaces chips packaged 689-pin packages pin compatible p1 family processors p3 series mid performance networking platform designed switching routing p3 family offers multi-core platform support four e500mc cores frequencies 1.5 ghz chip connected corenet coherency fabric chips include among integrated functionality integrated l3 caches memory controller multiple i/o-devices duart gpio usb 2.0 security encryption engines queue manager scheduling on-chip events serdes based on-chip high speed network configurable multiple gigabit ethernet 10 gigabit ethernet rapidio pcie interfaces p3 family processors share physical package also software backwards compatible p4 p5 p3 processors 1.3 ghz 64-bit ddr3 memory controllers 18 serdes lanes networking hardware accelerators packet handling scheduling regular expressions raid security cryptography rapidio cores supported hardware hypervisor run symmetric asymmetric mode meaning cores run boot operating systems together separately resetting partitioning cores datapaths independently without disturbing operating systems applications p4 series high performance networking platform designed backbone networking enterprise level switching routing p4 family offers extreme multi-core platform support eight e500mc cores frequencies 1.5 ghz chip connected corenet coherency fabric chips include among integrated functionality integrated l3 caches memory controllers multiple i/o-devices duart gpio usb 2.0 security encryption engines queue manager scheduling on-chip events serdes based on-chip high speed network configurable multiple gigabit ethernet 10 gigabit ethernet rapidio pcie interfaces cores supported hardware hypervisor run symmetric asymmetric mode meaning cores run boot operating systems together separately resetting partitioning cores datapaths independently without disturbing operating systems applications help software developers system designers get started qoriq p4080 freescale worked virtutech create virtual platform p4080 used prior silicon availability develop test debug software chip currently simulator p4080 chips announced 2008 complete set network engines processor used telecommunication systems lte enodeb epc wcdma bts freescale 6wind ported 6wind packet processing software p4080 p5 series based high performance 64-bit e5500 core scaling 2.5 ghz allowing numerous auxiliary application processing units well multi core operation via corenet fabric p5 series processors share physical package also software backwards compatible p3 p4 p5 processors 1.3 ghz 64-bit ddr3 memory controllers 18 serdes lanes networking hardware accelerators packet handling scheduling regular expressions raid security cryptography rapidio introduced june 2010 samples available late 2010 full production expected 2011 applications range high end networking control plane infrastructure high end storage networking complex military industrial devices february 2011 freescale introduced qoriq qonverge platform series combined cpu dsp soc processors targeting wireless infrastructure applications psc913x family chips uses e500 core based cpu starcore sc3850 dsps available 2011 manufactured 45 nm process e6500 cs3900 core based 28 nm parts available 2012 called p4xxx qoriq advanced multiprocessing amp series processors based multithreaded 64-bit e6500 core integrated altivec simd processing units except lowest end t1 family uses older e5500 core products range single core versions parts 12 cores frequencies ranging way 2.5 ghz processes sectioned five classes according performance features named t1 t5 manufactured 28 nm process beginning 2012 t4 family uses e6500 64-bit dual threaded core t2 family uses e6500 64-bit dual threaded core t1 family uses e5500 64-bit single threaded core 1.2 1.5 ghz 256 kb l2 cache per core 256kb shared corenet l3 cache qoriq products bring new challenges order design control planes telecommunication systems data plane instance 4 8 cores used p4080 order achieve millions packet processing per seconds system scale regular software stack many cores require different system design order restore simplicity still get highest level performance telecommunication systems based segregation cores cores used control plane others used re-designed data plane based fast path freescale partnered networking company 6wind provide software developers high-performance commercial packet processing solution qoriq platform
Computer architecture
anders hejlsberg anders hejlsberg born 2 december 1960 prominent danish software engineer co-designed several popular commercially successful programming languages development tools original author turbo pascal chief architect delphi currently works microsoft lead architect c core developer typescript hejlsberg born copenhagen denmark studied electrical engineering technical university denmark university 1980 began writing programs nascom microcomputer including pascal compiler initially marketed blue label software pascal nascom-2 however soon rewrote cp/m dos marketing first compas pascal later polypascal later product licensed borland integrated ide become turbo pascal system turbo pascal competed polypascal compiler largely inspired tiny pascal compiler niklaus wirth algorithms data structures programs one influential computer science books time borland hands turbo pascal became one commercially successful pascal compilers hejlsberg remained polydata company came financial stress 1989 moved california become chief engineer borland time developed turbo pascal became chief architect team produced delphi replaced turbo pascal 1996 hejlsberg left borland joined microsoft one first achievements j++ programming language windows foundation classes also became microsoft distinguished engineer technical fellow since 2000 lead architect team developing c language 2012 hejlsberg announced new microsoft project typescript superset javascript hejlsberg received 2001 dr. dobb excellence programming award work turbo pascal delphi c microsoft .net framework together shon katzenberger scott wiltamuth todd proebsting erik meijer peter hallam peter sollich anders awarded technical recognition award outstanding technical achievement work c language 2007 video available microsoft channel 9
Programming language topics
thread control block thread control block tcb data structure operating system kernel contains thread-specific information needed manage tcb manifestation thread operating system example information contained within tcb thread control block acts library information threads system specific information stored thread control block highlighting important information process
Computer architecture
proofpoint inc. proofpoint enterprise security company based sunnyvale california provides software service products inbound email security outbound data loss prevention social media mobile devices digital risk email encryption electronic discovery ediscovery ” email archiving claims half fortune 100 users solutions company founded june 2002 eric hahn formerly cto netscape communications launched july 21 2003 raising 7 million series funding round releasing first product lining six customers references backed venture investors benchmark capital stanford university additional 9 million series b funding led new york-based rre ventures announced october 2003 proofpoint became publicly traded company april 2012 time initial public offering ipo company shares traded 13 apiece investors purchased 6.3 million shares ipo raising 80 million company first product proofpoint protection server medium large businesses incorporated described mlx technology proprietary machine learning algorithms applied problem accurately identifying spam email using 10,000 different attributes differentiate spam valid email company joined dozens anti-spam software providers business opportunity fueled exponential increase spam volume threatening worker productivity making spam top business priority according 2004 national technology readinesed number spam detection attributes 50,000 2004 strict new hipaa regulations governing financial disclosures privacy health care data prompted proofpoint begin developing new products would automatically identify intercept outbound email containing sensitive information march 2004 proofpoint introduced first hardware appliance p-series message protection appliance later renamed proofpoint messaging security gateway using hardened linux kernel proofpoint protection server 2.0 software tested infoworld found stop 94 spam another product introduction november 2004 included protection server 3.0 email firewall mlx-based dynamic reputation analysis content security suite plug-in modules designed scanning outbound messages attachments assist compliance data protection regulations sarbanes-oxley hipaa gramm-leach-bliley combination known proofpoint messaging security gateway appliance reviewed channelweb proofpoint appliance stands guard e-mail gate channelweb nov 26 2004 observed used combination technologies policy-based management spam-filtering engine adaptive learning technology proofpoint introduced new product network content sentry add-on appliance content security suite august 2005 designed monitor online messaging email appliance monitors web mail message boards blogs ftp-based communications proofpoint also introduced policy-based email encryption features using identity-based encryption technology licensed voltage security step towards simpler operational requirements proofpoint messaging security gateway virtual edition released april 2007 product runs virtual appliance host running vmware virtual server software moving dedicated hardware appliance virtual server eliminates problems associated proprietary hardware reduces upgrade costs though require knowledge vmware virtual server architecture proofpoint messaging security gateway v5.0 released june 2007 based new integrated architecture combining capabilities single platform could run either dedicated appliance virtual appliance software suite icsa labs independent division verizon business announced april 2007 certified six anti-spam products new testing program one proofpoint messaging security gateway goal icsa labs anti-spam product testing certification evaluate product effectiveness detecting removing spam guidelines also address well products recognize e-mail messages legitimate sources moving software-as-a-service business proofpoint introduced proofpoint demand hosted version email security data loss prevention offerings may 2008 company hosted offerings expanded introduction proofpoint demand—standard edition product targeted small-to-medium size businesses need email security run servers on-site personnel proofpoint products designed solve three business problems advanced cybersecurity threats regulatory compliance brand-impostor fraud calls “ digital risk ” products work across email social media mobile devices cloud june 2008 proofpoint acquired fortiva inc. provider on-demand email archiving software legal discovery regulatory compliance email storage management fortiva used exchange journaling automatically archive internal external communications end users search archived messages including attachments directly search folder outlook proofpoint security portfolio includes products stop traditional cyberattacks delivered via malicious attachments urls socially engineered attacks—such business email compromise bec credential phishing—that use malware uses blend sandbox analysis reputational analysis automated threat data human threat intelligence attributes sender/recipient relationship headers content detect potential threats automated encryption data-loss prevention forensics-gathering tools designed speed incident response mitigate damage costs threats get portfolio also includes protection social-media account takeovers harmful mobile apps rogue wi-fi networks proofpoint compliance products designed reduce manual labor involved identifying potentially sensitive data managing supervising compliance government industry rules producing quickly e-discovery legal requests proofpoint digital risk products aimed companies seeking stop cybercriminals impersonating brand harm customers partners brand reputation email digital risk portfolio includes authentication technology prevent email domain spoofing social media stops scams fraudsters create fake customer-service accounts find people seeking help social media trick handing account credentials visiting malicious website mobile finds counterfeit apps distributed mobile app stores 2016 forrester wave™ digital risk monitoring q3 2016 proofpoint digital risk social media product included evaluation nine top vendors emerging market solutions monitor “ digital ” —i.e. social mobile web dark web—channels detect prevent malicious unwanted content undermining organizational efforts build brand across major social media platforms oct 23 2014 proofpoint acquired nexgate inc. social media security compliance vendor nov 4 2015 proofpoint acquired socialware inc compliance workflow content capture review technology company 2010 2011 2012 2013 2014 2015 2016 gartner magic quadrant identified proofpoint inc. leader “ magic quadrant secure email gateways ” seventh consecutive year gartner magic quadrant identified proofpoint inc. leader enterprise information archiving 2017 2017 sc magazine awards proofpoint inc. awarded best email security solution best regulatory compliance solution 2016 sc magazine award proofpoint inc. awarded best email security trust award forrester research named proofpoint inc. “ leader ” forrester wave™ digital risk monitoring q3 2016 nine vendors matter stack forrester credited proofpoint inc. report proofpoint stands rest pack strong portfolio patents related digital risk monitoring proofpoint essentials wins customers ’ choice award review platform expert insights may 2019
Computer security
phantasie phantasie fantasy role-playing video game series designed winston douglas wood published strategic simulations 1985 released apple ii atari 8-bit family atari st amiga commodore 64 ms-dos msx based isle gelnor phantasie allows group six characters adventure countryside try defeat evil black knights sorcerer leader nikademus players could choose one six character classes thief fighter ranger monk priest wizard could also choose races human dwarf halfling elf gnome selecting random one could also choose ogre troll pixie gnoll orc lizard man minotaur races 1986 ssi published next part series phantasie ii dark lord nikademus nemesis time nikademus fashioned evil orb cast curse beautiful island named ferronrah enslaved people player mission find destroy orb final installment trilogy based around fighting evil nikademus finishing good released 1987 time nikademus attempting take entire world party stop entry japan-exclusive pc-9801 msx english translation 50,000 copies sold north america phantasie successful ssi company best-selling commodore game late 1987 phantasie ii sold 30,100 copies phantasie iii sold 46,113 copies phantasie phantasie iii questron ii later re-released together reviewed 1994 dragon 203 sandy petersen eye monitor column petersen gave compilation 2 5 stars
Computer architecture
besys besys bell operating system early computing environment originally implemented batch processing operating system 1957 bell labs ibm 704 computer system developed bell recognized definite mismatch…between 704 internal speed sluggishness on-line unit-record equipment inherent slowness manual operations associated stand-alone use goals system initial version system besys-1 use october 16 1957 created george h. mealy gwen hansen wanda lee mammel guidance victor a. vyssotsky utilized ibm fortran north american symbolic assembly program sap programming languages designed efficiently deal large number jobs originating punched cards producing results suitable printing paper punched cards system also provided processing capabilities data stored magnetic tapes magnetic disk storage units typically punched card print processing handled line peripheral electronic accounting machines ibm 1401 computers eventually direct coupled computers first system actually used bell labs besys-2 system resident magnetic tape occupied lowest 64 36-bit words highest4 k words memory upper 4 k words held resident portion monitor could partially swapped magnetic drum free additional core user program needed besys complex software package provided convenient input/output integrated disk file storage facilities besys used extensively many departments bell labs decade made available share organization others without charge formal technical support versions besys environment besys-3 1960 besys-4 1962 besys-5 1963 besys-7 1964 be90 1968 implemented underlying computers transitioned ibm 709x family besys development discontinued bell labs moved ibm system/360 1969 throughout period head besys development project george l. baldwin
Operating systems
spysheriff spysheriff clones bravesentry pest trap spytrooper spywareno malwarealarm malware disguises anti-spyware software attempts mislead user false security alerts scaring buying program like rogue antiviruses producing list false threats prompts user pay remove software particularly difficult remove since nests components system restore folders also blocks system management tools however spysheriff removed experienced user antivirus software using rescue disk spysheriff hosted www.spysheriff.com www.spy-sheriff.com operated 2005 shutdown 2008 several similarly-named websites also hosted program shut several typosquatted websites also attempted automatically install spysheriff including fake version google.com called goggle.com 2015 goggle.com changed ownership following lawsuit google hosted survey scam displayed links amazon items 2017 domain hosted blank page word goggle present html script beginning 2018 site redirected scam site tango-deg.com october 2018 existed simple html markup top-level heading reading goggle.com inc
Computer security
/dev/random unix-like operating systems special files serve pseudorandom number generators allow access environmental noise collected device drivers sources typically blocks less entropy available requested typically never blocks even pseudorandom number generator seed fully initialized entropy since boot blocks boot seed securely initialized enough entropy never blocks operating systems implement methods provide random number generation kernel space implemented first time linux 1994 theodore ts implementation uses secure hashes rather ciphers avoid cryptography export restrictions place generator originally designed implementation also designed assumption given hash cipher might eventually found weak design durable face weaknesses fast recovery pool compromise considered requirement requirements pool compromise sufficient much easier direct attacks unrelated parts operating system ts implementation generator keeps estimate number bits noise entropy pool entropy pool random numbers created read codice_1 device return random bytes within estimated number bits noise entropy pool entropy pool empty reads codice_1 block additional environmental noise gathered intent serve cryptographically secure pseudorandom number generator delivering output entropy large possible suggested authors use generating cryptographic keys high-value long-term protection counterpart codice_1 codice_4 unlimited /non-blocking random source reuses internal pool produce pseudo-random bits means call block output may contain less entropy corresponding read codice_1 codice_4 still intended pseudorandom number generator suitable cryptographic purposes authors corresponding man page note theoretically may exist as-yet-unpublished attack algorithm used codice_4 users concerned attack use codice_1 instead however attack unlikely come existence entropy pool unpredictable n't leak security reduced number bits also possible write codice_1 allows user mix random data pool non-random data harmless privileged user issue ioctl needed increase entropy estimate current amount entropy size linux kernel entropy pool measured bits available codice_10 displayed command codice_11 codice_12 respectively gutterman pinkas reinman march 2006 published detailed cryptographic analysis linux random number generator describe several weaknesses perhaps severe issue report embedded live cd systems routers diskless clients bootup state predictable available supply entropy environment may limited system non-volatile memory recommend saving state rng shutdown included rng state next reboot case router network traffic represents primary available source entropy note saving state across reboots would require potential attackers either eavesdrop network traffic router first put service obtain direct access router internal state issue note particularly critical case wireless router whose network traffic captured distance may using rng generate keys data encryption linux kernel provides support several hardware random number generators installed raw output device may obtained codice_13 linux kernel 3.16 newer kernel mixes data hardware random number generators codice_1 sliding scale based definable entropy estimation quality hwrng means userspace daemon codice_15 codice_16 needed job linux kernel 3.17+ virtio rng modified default quality defined 0 currently hwrng mixed codice_1 default entropy pool improved programs like codice_18 codice_19 codice_20 etc codice_16 hardware random number generators like entropy key etc write codice_1 diehard tests programs codice_23 codice_24 codice_25 test random number generators january 2014 daniel j. bernstein published critique linux mixes different sources entropy outlines attack one source entropy capable monitoring sources entropy could modify output nullify randomness sources entropy consider function h x z h hash function x z sources entropy z output cpu based malicious hrng z bernstein estimated attacker would need repeat h x r 16 times compromise dsa ecdsa possible linux reseeds h ongoing basis instead using single high quality seed october 2016 release linux kernel version 4.8 newer codice_4 switched chacha20-based implementation theodore ts based bernstein well-regarded stream cipher chacha20 given standard shell script code uses /dev/urandom generates cryptmail heavily freebsd operating system provides codice_4 compatibility behavior different linux freebsd codice_4 link codice_1 blocks properly seeded freebsd prng fortuna reseeds regularly attempt estimate entropy system small amount network disk activity reseeding done fraction second entropy pool–based methods completely secure implemented correctly overestimate entropy may become less secure well-seeded prngs cases attacker may considerable amount control entropy example diskless server may get almost network rendering potentially vulnerable man-in-the-middle attacks since openbsd 5.1 may 1 2012 use algorithm based rc4 renamed intellectual property reasons arc4 random number generation uses system entropy gathered several ways arc4 algorithm provides fail-safe ensuring rapid high quality pseudo-random number stream provided even pool low entropy state system automatically uses hardware random number generators provided intel pci hubs available openbsd cryptographic framework openbsd 5.5 may 1 2014 call used openbsd random devices longer uses arc4 chacha20 arc4random name might reconsidered replacement call random netbsd implementation legacy api also switched chacha20 well macos uses 160-bit yarrow based sha1 difference /dev/random /dev/urandom behave identically apple ios also uses yarrow codice_1 codice_4 also available solaris netbsd tru64 unix 5.1b aix 5.2 hp-ux 11i v2 freebsd aix implements yarrow-based design however aix uses considerably fewer entropy sources standard codice_1 implementation stops refilling pool thinks contains enough entropy windows nt similar functionality delivered codice_33 reading special file codice_34 work unix documented methods generate cryptographically random bytes cryptgenrandom rtlgenrandom dos naturally provide functionality open-source third-party driver called codice_35 functions similarly creates two devices codice_36 codice_37 also accessible codice_38 codice_39 programs access random data linux emulator cygwin windows provide implementations codice_1 codice_4 used scripts programs
Computer file systems
exec shield exec shield project started red hat inc late 2002 aim reducing risk worm automated remote attacks linux systems first result project security patch linux kernel emulates nx bit x86 cpus lack native nx implementation hardware exec shield project many components people refer first patch exec shield first exec shield patch attempts flag data memory non-executable program memory non-writeable suppresses many security exploits stemming buffer overflows techniques relying overwriting data inserting code structures exec shield also supplies address space layout randomization mmap heap base patch additionally increases difficulty inserting executing shellcode rendering exploits ineffective application recompilation necessary fully utilize exec-shield although applications mono wine xemacs mplayer fully compatible features came exec shield project position independent executables pie address space randomization patch linux kernels wide set glibc internal security checks make heap format string exploits near impossible gcc fortify source feature port merge gcc stack-protector feature exec shield works x86 cpus utilizing code segment limit way exec shield works lightweight however wo n't fully protect arbitrary virtual memory layouts cs limit raised example calling mprotect make higher memory executable protections lost limit ingo molnar points e-mail conversation applications fairly sane stack important part least winds mapped libraries become executable except explicit calls application august 2004 nothing exec shield projects attempt enforce memory protections restricting mprotect architecture although memory may initially executable may become executable later kernel allow application mark memory pages writable executable time however cooperation security-enhanced linux project selinux standard policy fedora core distribution prohibit behavior executables exceptions compatibility reasons exec shield developed various people red hat first patch released ingo molnar red hat first released may 2003 part fedora core 1 6 red hat enterprise linux since version 3 people involved include jakub jelínek ulrich drepper richard henderson arjan van de ven
Operating systems
winexe winexe software allows administrator users execute commands remotely windowsnt/2000/xp/2003/vista/2003/2008 systems gnu/linux winexe distributed pre-built rpm packages source code available well winexe analogous sysinternals tool psexec
Internet protocols
npm software npm originally short node package manager package manager javascript programming language default package manager javascript runtime environment node.js consists command line client also called npm online database public paid-for private packages called npm registry registry accessed via client available packages browsed searched via npm website package manager registry managed npm inc. npm written entirely javascript developed isaac z. schlueter result seen module packaging done terribly inspiration similar projects pear php cpan perl npm included recommended feature node.js installer npm consists command line client interacts remote registry allows users consume distribute javascript modules available registry packages registry commonjs format include metadata file json format 477,000 packages available main npm registry registry vetting process submission means packages found low quality insecure malicious instead npm relies user reports take packages violate policies low quality insecure malicious npm exposes statistics including number downloads number depending packages assist developers judging quality packages npm version 6 audit feature introduced help developers identify fix vulnerability security issues installed packages source security issues taken reports found node security platform nsp integrated npm since npm acquisition nsp npm manage packages local dependencies particular project well globally-installed javascript tools used dependency manager local project npm install one command dependencies project codice_8 file codice_8 file dependency specify range valid versions using semantic versioning scheme allowing developers auto-update packages time avoiding unwanted breaking changes npm also provides version-bumping tools developers tag packages particular version npm also provides codice_10 file entry exact version used project evaluating semantic versioning codice_8 number open-source alternatives npm installing modular javascript including codice_12 codice_13 codice_14 codice_15 last released facebook october 2016 compatible public npm registry use default provide different client-side experiences usually focused improving performance determinism compared npm client jsconf 2019 npm former cto announced new federated package registry entropic aimed decentralisation javascript commons
Operating systems
convergent technologies operating system convergent technologies operating system also known variously ctos btos starsys modular message-passing multiprocess-based operating system ctos many innovative features time system access controlled user password volume disk passwords one knew password example volume one could access file directory volume hard disk volume directory referenced delimiters identify could followed file name depending operation i.e network node volumename directoryname filename possible custom-link operating system add delete features ctos supported transparent peer-to-peer network carried serial rs-422 cables daisy-chain topology later versions carried twisted pair star topology rs-422 adapters workgroup called cluster connected server called master workstations normally diskless booted cluster network master could optionally locally booted attached hard drives inter-process communication ipc primarily based request respond messaging foundation enhanced enterprise application integration among services internal external environments thus ctos well known message-based microkernel architecture applications added services main server client consumes services via mailbox called exchange well-published message formats communication works request codes owned service operating system maintains exchanges message queues scheduling control message passing etc. service manages messages exchange using wait check respond macros ctos ran intel x86 computers could run concurrently windows nt unisys pc system api presented high-level languages assembly language assembler advanced lisp-like pattern-matching macro facility unmatched almost assembler since always-resident debugger system programs written pl/m algol-like language intel compiled directly object code without runtime library word processor one first screen-oriented editors many high-powered features multiple views file cut/copy/paste unlimited undo/redo typing lost crash power failure user-selectable fonts much spreadsheet allowed blocks cells protected editing user input btos version allowed scripts written included opening spreadsheet user input automatically printing graphs based input data system shell extensible making possible define new commands get parameters system would display form filled user input form conventions mandatory optional input fields made easy train new users convergent technologies first product iws integrated workstation based intel 8086 processor ctos operating system modular operating system built-in local area networking ctos supported multiple processes threads message-based interprocess communication companies licensed ctos included bull starsys burroughs btos later merged sperry become unisys unisys single largest customer convergent technologies merged become one company 1988 peak ctos 800,000 users worldwide diskless workstations e.g. bull used intel 80186 processor processor seldom used standard pcs progress software corporation made commercial database application ctos 4gl united states coast guard used databases logistics administration vessels port coreldraw ctos running presentation manager ctos longer marketed new customers former major customers included police forces banks airlines u.s postal service drug enforcement administration u.s. army united states coast guard coast guard used operating system approximately 1986 2000 australia ctos/btos used trade practices commission nsw auditor-general csiro commonwealth electoral office western australia prisons department many commercial banks
Operating systems
web services description language web services description language wsdl xml-based interface description language used describing functionality offered web service acronym also used specific wsdl description web service also referred wsdl file provides machine-readable description service called parameters expects data structures returns therefore purpose roughly similar type signature programming language current version wsdl wsdl 2.0 meaning acronym changed version 1.1 stood definition wsdl describes services collections network endpoints ports wsdl specification provides xml format documents purpose abstract definitions ports messages separated concrete use instance allowing reuse definitions port defined associating network address reusable binding collection ports defines service messages abstract descriptions data exchanged port types abstract collections supported operations concrete protocol data format specifications particular port type constitutes reusable binding operations messages bound concrete network protocol message format way wsdl describes public interface web service wsdl often used combination soap xml schema provide web services internet client program connecting web service read wsdl file determine operations available server special datatypes used embedded wsdl file form xml schema client use soap actually call one operations listed wsdl file using example xml http current version specification 2.0 version 1.1 endorsed w3c version 2.0 w3c recommendation wsdl 1.2 renamed wsdl 2.0 substantial differences wsdl 1.1 accepting binding http request methods get post version 1.1 wsdl 2.0 specification offers better support restful web services much simpler implement however support specification still poor software development kits web services often offer tools wsdl 1.1 example version 2.0 business process execution language bpel supports wsdl 1.1 subset wsdl swsdl wsdl subset operations original wsdl developer use swsdl access subset service thus handle subset web service code subset wsdl used perform web service testing top development slicing web service done using subset wsdl access subset service subset service categorized layers using swsdl swsdls used web service analysis testing top development awscm pioneer tool construct swsdl successfully xml version= 1.0 encoding= utf-8 description xmlns= http //www.w3.org/ns/wsdl documentation /documentation -- abstract type -- -- abstract interfaces -- -- concrete binding http -- -- concrete binding soap -- -- web service offering endpoints bindings -- /description wsdl 1.0 sept. 2000 developed ibm microsoft ariba describe web services soap toolkit built combining two service description languages nassl network application service specification language ibm sdl service description language microsoft wsdl 1.1 published march 2001 formalization wsdl 1.0 major changes introduced 1.0 1.1 wsdl 1.2 june 2003 working draft w3c become wsdl 2.0 according w3c wsdl 1.2 easier flexible developers previous version wsdl 1.2 attempts remove non-interoperable features also defines http 1.1 binding better wsdl 1.2 supported soap servers/vendors wsdl 2.0 became w3c recommendation june 2007 wsdl 1.2 renamed wsdl 2.0 substantial differences wsdl 1.1 changes following since wsdl files xml-based specification describing web service wsdl files susceptible attack mitigate vulnerability files limiting access generated wsdl files setting proper access restrictions wsdl definitions avoiding unnecessary definitions web services encouraged
Web technology
scaleform gfx scaleform gfx game development middleware package vector graphics rendering engine used display adobe flash-based user interfaces huds video games result autodesk acquisition scaleform corporation march 2011 scaleform gfx became part autodesk gameware line middleware july 12th 2018 autodesk discontinued scaleform gfx longer available purchase authors created user interfaces using adobe flash authoring tools adobe flash professional resulting swf files could used directly gfx libraries providing similar functionality adobe flash player optimized use within game engines major platforms supported including game consoles mobile pc operating systems scaleform provided apis direct communication flash content game engine pre-built integrations popular engines unity unreal engine cryengine scaleform gfx could also licensed use standalone flash runtime system mobile platforms competing adobe air scaleform gfx contained several core systems including addition engine documentation samples scaleform gfx sdk included several additional components scaleform also provided two optional add-ons gfx
Distributed computing architecture
intel 8251 8251 universal synchronous/asynchronous receiver/transmitter packaged 28-pin dip made intel typically used serial communication rated per second signalling rate commonly confused much common 8250 uart made popular serial port ibm personal computer includes 5 sections version 8251a available us 6.40 quantity 100 intel 8251a used intel sdk-86 mcs-86 system design kit dec la120 printing terminal
Computer architecture
virtual router redundancy protocol virtual router redundancy protocol vrrp computer networking protocol provides automatic assignment available internet protocol ip routers participating hosts increases availability reliability routing paths via automatic default gateway selections ip subnetwork protocol achieves creation virtual routers abstract representation multiple routers i.e master backup routers acting group default gateway participating host assigned virtual router instead physical router physical router routing packets behalf virtual router fails another physical router selected automatically replace physical router forwarding packets given time called master router vrrp provides information state router routes processed exchanged router vrrp instance limited scope single subnet advertise ip routes beyond subnet affect routing table way vrrp used ethernet mpls token ring networks internet protocol version 4 ipv4 well ipv6 protocol described internet engineering task force ietf publication rfc 5798 open standard cisco claims similar protocol essentially facility patented licensed however reply direct request robert barr cisco replied 2001 assert patent claims unless someone tried assert claim cisco ibm also claims covering patents statement readable ietf webpage virtual router must use 00-00-5e-00-01-xx media access control mac address last byte address xx virtual router identifier vrid different virtual router network address used one physical router time reply mac address arp request sent virtual router ip address physical routers within virtual router must communicate within using packets multicast ip address 224.0.0.18 ip protocol number 112 routers priority 1 254 router highest priority become master default priority 100 mac address owner priority always 255 failure receive multicast packet master router period longer three times advertisement timer causes backup routers assume master router dead virtual router transitions unsteady state election process initiated select next master router backup routers fulfilled use multicast packets backup router supposed send multicast packets election process one exception rule physical router configured higher priority current master means connection network preempt master status allows system administrator force physical router master state immediately booting example particular router powerful others within virtual router backup router highest priority becomes master router raising priority current master take responsibility routing packets sent virtual gateway mac address cases backup routers priority backup router highest ip address becomes master router physical routers acting virtual router must local area network lan segment communication within virtual router takes place periodically period adjusted changing advertisement interval timers shorter advertisement interval shorter black hole period though expense traffic network security achieved responding first hop packets though mechanisms provided reinforce particularly local attacks election process made orderly use skew time derived router priority used reduce chance thundering herd problem occurring election skew time given formula 256 − priority /256 expressed milliseconds backup router utilization improved load sharing see rfc 5798 vrrp based cisco proprietary hot standby router protocol hsrp concepts protocols similar concept compatible
Internet protocols
blancco technology group plc blancco technology group global provider mobile device diagnostics secure data erasure products company divided two distinct business units blancco data erasure smartchk mobile diagnostics data erasure solution providers blancco technology group holds highest number certifications approvals recommendations national international governing bodies including united states department defense nato tuv saarland dipcog originally known regenersis plc lse rgs blancco technology group plc lse bltg formed 2016 result number software business acquisitions following acquisitions regenersis disposed repair division focus pure-play software business renamed blancco technology group plc company divided two distinct business units blancco data erasure smartchk mobile diagnostics blancco technology group employs 240 people worldwide across north america europe asia australia company headquartered alpharetta ga united states certified data erasure software hardware see blancco mobile device diagnostics software business intelligence see smartchk blancco technology group started regenersis plc provider diagnostics repair data erasure services consumer electronics industry regenersis filed ipo 2005 public company london stock exchange year acquired intec group intec cellular services intec distribution blancco technology group partners multiple resellers distributors including asset disposition vendors mobile services recycling providers data centers cloud storage providers
Computer security
high sierra format high sierra format hsf early logical file system used cd-roms 1985 1986 later ecma-119 iso 9660 standards based revised hsf compact discs originally developed recording musical data soon used storing additional digital data types equally effective archival mass data storage first every cd-rom maker created format high-level standards yellow book cd-rom standard lowest level need standard organizing data compact disks logical units files order develop cd-rom file system standard z39.60 volume file structure cdrom information interchange national information standards organization niso set standards committee sc ee compact disc data format july 1985 september/ october 1985 several companies invited experts participate development working paper standard november 1985 representatives computer hardware manufacturers gathered high sierra hotel casino currently called hard rock hotel casino near lake tahoe california group became known high sierra group hsg present meeting representatives apple computer digital equipment corporation dec hitachi laserdata microware microsoft 3m philips reference technology inc. sony corporation tms inc. videotools later meridian xebec yelick meeting report evolved yellow book cd-rom standard data cds open ended leading diversification creation many incompatible data storage methods high sierra group proposal hsgp released may 1986 draft version submitted european computer manufacturers association ecma changes led issue initial edition ecma-119 standard december 1986 ecma submitted standard international standards organization iso fast tracking refined iso 9660 compatibility second edition ecma-119 revised equivalent iso 9660 december 1987. published 1988 ecma-119 iso 9660 needed hsf geared primarily towards needs us market international extensions bulk differences formats order create incompatibilities niso suspended work z39.60 adopted niso members 28 may 1987 withdrawn final approval favour iso 9660
Computer file systems
fedora media writer fedora media writer formerly fedora live usb creator free open-source tool designed create live usb operating systems
Operating systems
opensolaris system z opensolaris system z discontinued port opensolaris operating system ibm system z line mainframe computers opensolaris based solaris originally released sun 1991 sun microsystems released bulk solaris system source code opensolaris 14 june 2005 made possible developers create opensolaris distributions sine nomine associates began project bring opensolaris ibm mainframe july 2006 project named sirius analogy polaris project port opensolaris powerpc april 2007 sine nomine presented initial progress report ibm system z technical expo conference gartner data center conference las vegas nevada late 2007 sine nomine demonstrated opensolaris running ibm system z z/vm david boyes sine nomine stated opensolaris system z would available soon share conference 13 august 2008 neale ferguson sine nomine associates presented update progress opensolaris system z presentation included working demonstration opensolaris system z presentation stated opensolaris ready prime-time hoped version available public testing matter weeks rather months october 2008 sine nomine associates released first prototype lacks number features dtrace solaris containers ability act nfs server opensolaris system z public opensolaris system z project page opensolaris.org opensolaris system z available download charge governed open source license terms opensolaris platforms source code available oco object code modules port uses z/architecture 64-bit addressing therefore requires ibm system z mainframe port depends recently defined z/architecture processor instructions requires system z9 later mainframe model run older machines also run release version hercules mainframe emulator needed changes included svn version 5470 hercules also requires paravirtualization features provided z/vm run bare metal logical partition lpar without z/vm hypervisor version 5.3 level later also opensolaris uses new network diagnose instruction ptf vm64466 vm64471 must applied z/vm provide support instruction 18 november 2008 ibm authorized use ifl processors run opensolaris system z workloads register reported march 2010 email insider saying
Operating systems
program status word program status word psw ibm system/360 architecture successors control register performs function status register program counter architectures although certain fields within psw may tested set using non-privileged instructions testing setting remaining fields may accomplished using privileged instructions contained within psw two bit condition code representing zero positive negative overflow similar flags architectures status registers conditional branch instructions test encoded four bit value bit representing test one four condition code values 2 2 2 2 since ibm uses big-endian bit numbering mask value 8 selects code 0 mask value 4 selects code 1 mask value 2 selects code 2 mask value 1 selects code 3 64-bit psw describes among things early instances architecture system/360 early system/370 instruction address 24 bits later instances xa/370 instruction address 31 bits plus mode bit 24 bit addressing mode zero 31 bit addressing mode one total 32 bits present instances architecture z/architecture instruction address 64 bits psw 128 bits psw may loaded load psw instruction lpsw lpswe contents may examined extract psw instruction epsw
Computer architecture
scilab scilab free open-source cross-platform numerical computational package high-level numerically oriented programming language used signal processing statistical analysis image enhancement fluid dynamics simulations numerical optimization modeling simulation explicit implicit dynamical systems corresponding toolbox installed symbolic manipulations scilab one two major open-source alternatives matlab one gnu octave scilab puts less emphasis syntactic compatibility matlab octave similar enough authors suggest easy transfer skills two systems scilab high-level numerically oriented programming language language provides interpreted programming environment matrices main data type using matrix-based computation dynamic typing automatic memory management many numerical problems may expressed reduced number code lines compared similar solutions using traditional languages fortran c c++ allows users rapidly construct models range mathematical problems language provides simple matrix operations multiplication scilab package also provides library high-level operations correlation complex multidimensional arithmetic software used signal processing statistical analysis image enhancement fluid dynamics simulations numerical optimization scilab also includes free package called xcos fork scicos based modelica language modeling simulation explicit implicit dynamical systems including continuous discrete sub-systems xcos open source equivalent simulink mathworks syntax scilab similar matlab scilab includes source code translator assisting conversion code matlab scilab scilab available free cost open source license due open source nature software user contributions integrated main program scilab syntax largely based matlab language simplest way execute scilab code type prompt codice_1 graphical command window way scilab used interactive mathematical shell hello world scilab plotting 3d surface function v scilab many contributed toolboxes different tasks available atoms portal scilab forge scilab created 1990 researchers inria école nationale des ponts et chaussées enpc initially named ψlab psilab scilab consortium formed may 2003 broaden contributions promote scilab worldwide reference software academia industry july 2008 order improve technology transfer scilab consortium joined digiteo foundation scilab 5.1 first release compiled mac available early 2009 supported mac os x 10.5 a.k.a leopard thus osx 10.4 tiger never supported except porting sources linux windows builds released since beginning solaris support dropped version 3.1.1 hp-ux dropped version 4.1.2 spotty support june 2010 consortium announced creation scilab enterprises scilab enterprises develops markets directly international network affiliated services providers comprehensive set services scilab users scilab enterprises also develops maintains scilab software ultimate goal scilab enterprises help make use scilab effective easy february 2017 scilab 6.0.0 released leveraged latest c++ standards lifted memory allocation limitations since july 2012 scilab developed published scilab enterprises early 2017 scilab enterprises acquired virtual prototyping pioneer esi group since 2016 scilab embedded browser called via interface written scilab api new deployment method notable advantages masking code data well providing large computational power
Programming language topics
features new windows xp windows xp introduced many features found previous versions windows introduction windows xp c++ based software-only gdi+ subsystem introduced replace certain gdi functions gdi+ adds anti-aliased 2d graphics textures floating point coordinates gradient shading complex path management bicubic filtering intrinsic support modern graphics-file formats like jpeg png support composition affine transformations 2d view pipeline gdi+ uses argb values represent color use features apparent windows xp user interface transparent desktop icon labels drop shadows icon labels desktop shadows menus translucent blue selection rectangle windows explorer sliding task panes taskbar buttons several applications microsoft paint windows picture fax viewer photo printing wizard pictures slideshow screensaver presence basic graphics layer greatly simplifies implementations vector-graphics systems flash svg gdi+ dynamic library shipped application used older versions windows total number gdi handles per session also raised windows xp 16384 65536 configurable registry windows xp shipped directx 8.1 brings major new features directx graphics besides directx audio directsound directmusic directplay directinput directshow direct3d introduced programmability form vertex pixel shaders enabling developers write code without worrying superfluous hardware state fog bump mapping texture mapping directx 9 released 2003 also sees major revisions direct3d directsound directmusic directshow direct3d 9 added new version high level shader language support floating-point texture formats multiple render targets texture lookups vertex shader windows xp upgraded directx 9.0c shader model 3.0 later included windows xp sp2 windows xp sp3 added windows imaging component windows xp includes cleartype subpixel rendering makes onscreen fonts smoother readable liquid crystal display lcd screens although cleartype effect crt monitors primary use lcd/tft-based laptop notebook modern 'flatscreen displays cleartype windows xp currently supports rgb bgr sub pixel structures parameters contrast set via cleartype tuner powertoy microsoft makes available free download typography website windows xp start button updated support fitts law help user access wider range common destinations easily single location start menu expanded two columns left column focuses user installed applications right column provides access user documents system links previously located desktop links documents pictures special folders brought fore computer network places network neighborhood windows 95 98 icons also moved desktop start menu making easier access icons number applications open desktop remains clean moreover links configured expand cascading menu frequently used programs automatically displayed left column newly installed programs highlighted user may opt pin programs start menu always accessible without navigate programs folders default internet browser default email program pinned start menu start menu fully customizable links added removed number frequently used programs display set programs menu expands like classic start menu utilize entire screen set scroll programs user name user account picture also shown start menu taskbar buttons running applications quick launch also updated fitt law locking taskbar prevents accidentally resized moved elements quick launch deskbands also locked accidentally moved taskbar grouping feature combines multiple buttons application single button clicked pops menu listing grouped windows number advanced taskbar grouping options configured registry user choose always show always hide hide notification area icons inactive time button allows user reveal icons taskbar set thicker height also displays day date notification area significant changes made windows explorer windows xp visually functionally microsoft focused especially making windows explorer discoverable task-based well adding number features reflect growing use computer “ digital hub ” task pane displayed left side window instead traditional folder tree view navigation pane turned presents user list common actions destinations relevant current directory file selected instance directory containing mostly pictures set “ picture tasks ” shown offering options display pictures slide show print go online order prints conversely folder containing music files would offer options play files media player go online purchase music every folder also “ file folder tasks ” offering options create new folders share folder local network publish files folders web site using web publishing wizard common tasks like copying renaming moving deleting files folders file types identified printable also option listed print file underneath “ file folder tasks ” “ places ” always lists parent folder folder viewed includes additional links common locations “ computer ” “ control panel ” “ documents ” previously navigated locations change depending folder user underneath “ places ” “ details ” area gives additional information file folder selected – typically file type file size date modified depending file type author image dimensions attributes details file type thumbnail image handler installed preview also appears details task pane music files might show artist album title length song information also shown horizontally status bar “ folders ” button windows explorer toolbar toggles traditional navigation pane containing tree view folders task pane users also close navigation pane clicking close button right corner well turn task pane folder options navigation pane enhanced windows xp support simple folder view turned hides dotted lines connect folders subfolders makes folders browsable single click still keeping double clicking right pane single clicking simple folder view auto expands folder clicking another folder automatically expands folder collapses previous one windows xp introduced large number metadata properties shown columns details view explorer new tiles view explorer summary tab file properties file tooltip explorer status bar single file selected users also gain ability sort property turned details view developers write column handler shell extensions define properties files sorted column items sorted highlighted sorting files folders ascending order descending order views details view reverse order user simply perform sort property sort order also made intuitive compared one windows 2000 file names containing numbers windows explorer tries sort based numerical value rather comparing number digit digit every character position file name instance files containing 1 2 .. 10 intuitively sorted 10 appearing 9 instead appearing 1 2 right pane windows explorer show groups feature allows explorer separate contents headings based field used sort items items thus grouped detail turned show groups available thumbnails tiles icons details views microsoft introduced animated search companions attempt make searching engaging friendly default character puppy named rover three characters merlin magician earl surfer courtney also available search companions powered microsoft agent technology bear great deal similarity microsoft office ’ office assistants even incorporating “ tricks ” sound effects user wishes also turn animated character entirely search capability fairly similar windows windows 2000 important additions indexing service extract exif properties well metadata asf wmv mp3 files windows xp via ipropertystorage interface using built-in null filter search also instructed search files categorically “ documents ” “ pictures music video searching perceived type feature noteworthy largely windows determines types files classified categories another important addition look field accepts expands environment variables abbreviated entry long paths also users configure whether windows xp searches system and/or hidden files folders using tweak ui search user interface restored one used windows 2000 windows xp improves image preview offering filmstrip view shows images single horizontal row large preview currently selected image “ back ” “ previous ” buttons facilitate navigation pictures pair “ rotate ” buttons offer 90-degree clockwise counter-clockwise rotation images filmstrip view like view turned per folder view available new common tasks folder view selected windows classic folder view aside filmstrip view mode 'thumbnails view displays thumbnail-sized images folder also displays images subfolder may containing 4 default overlaid large folder icon folder thumbnail view customized customize tab accessible properties users also change folder icon specify template type pictures music videos documents folder optionally subfolders size quality thumbnails thumbnails view adjusted using tweak ui registry exif metadata stored image also shown file properties summary tab details view view status bar windows xp optionally caches thumbnails thumbs.db file folder pictures thumbnails generated faster next time thumbnails forced regenerate right-clicking image thumbnail filmstrip views selecting refresh thumbnail autoplay examines newly discovered removable media devices based content pictures music video files launches appropriate application play display content autoplay confused autorun created order simplify use peripheral devices – mp3 players memory cards usb storage devices others – automatically starting software needed access view content devices autoplay enhanced autoplay-compatible software hardware configured user associate favourite applications autoplay events actions actions called autoplay handlers sets handlers associated various types content new autoplay handlers get added system additional software installed user edit delete create autoplay handlers using tweakui autoplay settings configured per-device windows xp device properties user inserts optical disc drive attaches usb camera windows detects arrival starts process examining device searching medium looking properties device content medium autoplay present set meaningful options user user makes particular choice also option make selection automatic next time windows sees content device content types available vary type drive selected windows xp includes windows picture fax viewer based gdi+ capable viewing image formats supported gdi+ namely jpeg bmp png gif including animated gifs ico wmf emf tiff format files supersedes part functions imaging windows previous versions windows windows picture fax viewer integrated windows explorer functions like slideshow email printing etc quickly starts image double clicked windows explorer supports full file management within viewer right clicking image shows context menu one shown image right clicked windows explorer images set desktop wallpaper context menu supports successive viewing images current folder looping images viewing last image directory shows first image vice versa default images smaller user display resolution shown actual size image larger display resolution scaled fit screen best fit images zoomed depending viewing area done scroll bars allow viewing areas image standard toolbar buttons delete print copy open copy button converts image different format supported gdi+ jpeg bmp gif tiff png print button starts photo printing wizard allows printing images picture titles using various page layouts full page prints wallet prints contact/index sheets certain fixed dimensions images cropped rotated fit page wizard shows preview printed page look like currently specified options windows picture fax viewer also rotate images clockwise anti-clockwise start slideshow selected images folder e-mail selecting send mail recipient option options allow image mailed full size pixel dimensions 640 x 480 800 x 600 1024 x 768 using tweak ui time images slideshow adjusted windows picture fax viewer recognizes embedded icc v2 color profiles jpg tiff files gif files shown full animation even zoomed tiff files annotated using annotation toolbar appears bottom screen lines drawn tiff image text added areas image selected concealed windows picture fax viewer also capable viewing multi-page tiff files however tiff images jpeg compression fully supported last button standard toolbar opens image editing default microsoft paint however editing application registered button viewer windows picture fax viewer saves remembers window position size supports keyboard shortcuts operations raw image formats preferred formats professional photography supported however microsoft released later update called raw image thumbnailer viewer windows xp viewing certain raw image files text services framework tsf com framework api introduced windows xp supports advanced text input text processing text services framework designed offer advanced language word processing features applications supports features multilingual support keyboard drivers handwriting recognition speech recognition well spell checking text natural language processing functions also downloadable older windows operating systems language bar core user interface text services framework language bar enables text services add ui elements toolbar enables elements application focus language bar users select input language control keyboard input handwriting recognition speech recognition language bar also provides direct means switch installed languages even non-tsf-enabled application focus windows xp kernel completely different kernel windows 9x/me line operating systems although upgrade windows 2000 kernel major scalability stability performance improvements albeit transparent end user windows xp includes simultaneous multithreading hyperthreading support simultaneous multithreading processor ability process one data thread time windows xp supports larger system virtual address space –— 1.3 gb contiguous virtual address space used device drivers 960 mb windows xp memory manager redesigned consume less paged pool allowing caching greater availability paged pool component needs total size memory-mapped files windows 2000 limited memory manager allocated prototype page table entries pptes pages required map entire file even application created mapped views parts file windows xp prototype ptes allocated active views allowing larger mapped files benefit example case making backups large files low memory systems paged pool limit 470 mb lifted memory manager windows xp unmapped views dynamically reusable memory manager depending pool usage memory pages working sets trimmed efficiently multiprocessor systems depending recently accessed lock contention reduced number unnecessary locks used resource synchronizations ram allocation mapping address windowing extensions system page table entries charging non-paged/paged pool quotas charging commitment pages removed dispatcher lock contention reduced page frame number pfn lock optimized increased parallelism granularity windows xp uses push locks event synchronization object contention support shared exclusive acquisition push locks used protect handle table entries executive object manager protect data structures security descriptors memory manager protect awe-related locks windows xp uses sysenter/sysexit mechanisms require fewer clock cycles transition user mode kernel mode speed system calls kernel page write protection limit windows xp enabled systems 256 mb ram beyond large pages enabled increased address translation performance windows xp introduces creatememoryresourcenotification function notify user mode processes high low memory availability applications allocate memory free memory necessary previous versions windows registry size limited 80 paged pool size windows xp registry reimplemented outside paged pool registry hives memory mapped cache manager system cache eliminating registry size limit registry size limited available disk space system hive still maximum size raised 12 mb 200 mb eliminating issue previous windows versions faced unable boot large fragmented system hive configuration manager updated minimize registry memory footprint lock contention reduce fragmentation thus page faults accessing registry improved algorithms speed registry query processing in-memory security cache eliminates redundant security descriptors windows xp supports cross user session debugging attaching debugger non-crashing user-mode program dumping process memory space using dump command detaching debugger without terminating debugging done firewire port local system debug heap disabled standard heap used debugging windows xp introduces support vectored exception handling vectored exception handling made available windows programmers using languages c++ visual basic veh replace structured exception handling seh rather veh seh coexist veh handlers priority seh handlers compared seh veh works like traditional notification callback scheme applications intercept exception calling addvectoredexceptionhandler api watch handle exceptions vectored handlers chained order linked list n't tied stack frame added anywhere call stack unlike seh try/catch blocks heap leak detection enabled processes exit debugger extension used investigate leaks also introduced new heap performance-monitoring counter windows xp introduces new low fragmentation heap policy disabled default allocates memory distinct sizes blocks less 16kb reduce heap fragmentation low fragmentation heap enabled default heaps using lfh heap enabler utility new apis irp cancellation registering file system filter callbacks intercept os fast i/o functions low memory conditions must succeed calls denied causing slowdown preventing bug check i/o throttled fetch one memory page time increasing overall scalability windows xp includes ntfs 3.1 expands master file table mft entries redundant mft record number useful recovering damaged mft files ntfs conversion utility convert.exe supports new /cvtarea switch ntfs metadata files written contiguous placeholder file resulting less fragmented file system conversion ntfs 3.1 also supports symbolic links although tools drivers shipped windows xp create symbolic links windows xp introduces ability mount ntfs read-only volumes new apis preserve original short file names retrieve list mount points drive letters mounted folder paths specified volume enable applications create large files quickly setting valid data length files without force-writing data zeroes vdl setfilevaliddata function instance function used quickly create fixed size virtual machine hard disk default access control lists newly created files read-only users group write permissions given administrators group system account owner ability boot 30 seconds design goal windows xp microsoft developers made efforts streamline system much possible logical prefetcher significant part monitors files loaded boot optimizes locations files disk less time spent waiting hard drive heads move issues large asynchronous i/o requests overlapped device detection initialization occurs boot prefetcher works tracing frequently accessed paged data used task scheduler create prefetch-instructions file windir \prefetch system boots application started data code specified trace already memory prefetched disk previous prefetching results determine scenario benefited prefetched next boot launch prefetcher also uses algorithms reduce application startup times reduce disk seeking even disk defragmenter called idle time optimize layout specific files metadata contiguous area boot resume operations traced analyzed using bootvis.exe windows xp includes fast logon optimization feature performs logon asynchronously without waiting network fully initialized roaming user profiles set use cached credentials avoids delays logging domain group policy applied background startup logon scripts execute asynchronously default windows xp reconciles local roaming user profiles using copy contents registry user longer made wait windows 2000 profile unloaded windows xp saves locked registry hives open keys 60 seconds roaming profile changes saved back server problem left computer recover memory profile uses unloaded make sure user profiles completely reconciled correctly logoff microsoft released user profile hive cleanup service windows xp later included windows vista windows xp offers enhancements usability resilience corruption performance roaming user profiles new group policies prevent propagation roaming user profile changes server give administrators control users profile folders preventing use roaming user profiles specific computers accommodate scenario older profile would overwrite newer server profile due windows xp fast logon feature windows xp ensures situation user registry hive copied server local profile deletion profiles marked deletion next logoff fail locked profiles workgroup computers windows xp longer deletes profiles users belonging guests group windows xp includes changes behavior offline files offline files client-side cache encrypted encrypting file system shared folders dfs namespaces made available offline also roaming user profiles synchronized server even offline files marked server unavailable windows xp service pack 2 kb811660 introduce additional functionality offline files editing registry users suppress error messages file types offline files cache excluded synchronization offline files user primary computer determined matching current user sid specified sid registry set purge logoff administratively assigned offline files also prevented cached non-primary users beginning windows xp folders redirected network automatically made available offline using offline files although optionally disabled group policy older windows nt 4.0 earlier systems legacy directory structure windows xp allows redirecting documents folder home directory windows xp improvements made system restore compared windows system restore uses copy-on-write file system filter driver taking snapshots windows xp system restore configurable per volume data stores also stored per volume ntfs volumes restore points stored using ntfs compression protected using acls disk cleanup handler allows deleting recent restore point besides registry hives system files com+ wmi databases iis metabase also restored system restore supports group policy system restore windows xp also works without issues efs-encrypted files automated system recovery feature provides ability save restore windows installed applications system state critical boot system files special backup instead plain reinstall asr consists two components backup restore backup portion located ntbackup backs system state windows registry com+ class registration database active directory sysvol directory share volumes associated operating system components required start windows restore well configuration basic dynamic restore portion asr accessed pressing f2 windows xp text mode setup automated system recovery even restore programs device drivers added asr setup information disk asr restore data files common issue previous versions windows users frequently suffered dll hell one version dynamically linked library dll installed computer software relies dlls using wrong version could result non-functional applications worse windows 98 second edition windows 2000 partially solved problem native code introducing side-by-side component sharing dll/com redirection operating systems allowed loading private version dll placed application folder developer instead system directory must registered properly system windows xp improves upon introducing side-by-side assemblies com+ 2.0 .net com classic win32 components c runtime gdi+ common controls technology keeps multiple digitally signed versions shared dll centralized winsxs folder runs demand appropriate application keeping applications isolated using common dependencies manifests assembly version number used os loader determine correct binding assembly versions applications instead globally registering components achieve windows xp introduces new mode com object registration called registration-free com regfree com allows component object model com components store activation metadata clsid codice_1 component without using registry instead metadata clsids classes implemented component declared assembly manifest described using xml stored either resource executable separate file installed component allows multiple versions component installed different directories described manifests well xcopy deployment application loading windows loader searches manifest present loader adds information activation context com class factory tries instantiate class activation context first checked see implementation clsid found lookup fails registry scanned windows error reporting collects offers send post-error debug information memory dump using internet developer application crashes stops responding user desktop data sent without user consent dump error signature information reaches microsoft server analyzed solution sent back user one available windows error reporting runs windows service optionally entirely disabled software hardware manufacturers may access error reports using microsoft winqual program software hardware manufacturers also close loop customers linking error signatures windows error reporting responses allows distributing solutions well collecting extra information customers reproducing steps took crash providing support links old versions windows users upgrade device driver chance new driver less stable efficient functional original reinstalling old driver major hassle avoid quandary windows xp keeps copy old driver new version installed new driver problems user return previous version feature work printer drivers windows xp merged consumer enterprise versions windows needed support applications developed popular consumer-oriented windows 9x platform windows nt kernel microsoft addressed improving compatibility application-specific tweaks shims providing tools application compatibility toolkit appcompat act allow users apply automate tweaks shims applications users script compatibility layer using batch files windows xp setup also includes compatibility checker warns users setup begins incompatible applications device drivers applications may need reinstallation windows xp rtm includes windows media player version 8 officially called windows media player windows xp windows media 8 codecs windows media player windows xp introduced id3 support mp3s editing media information within library adding lyrics mp3 wma tracks file name customization ripping new visualizations support hdcds ability lockdown player corporate environment dvd playback support appropriate codecs installed separately windows xp sp2 includes windows media player 9 series windows media format runtime 9.0 upgradeable version 11 player format runtime windows media player also incorporates newer hardware support portable devices means media transfer protocol user-mode driver framework-based windows portable devices api original rtm release windows xp included windows movie maker 1.1 added non-compressed dv avi recording digital video sources windows movie maker 2 free download released 2002 later incorporated windows xp sp2 windows movie maker 2 introduced numerous new transitions effects titles credits task pane resizable preview window dimensions improved capture export options automovie feature saving final video back tape custom wmv export profiles windows xp media center edition 2005 includes windows movie maker 2.5 includes dvd burning windows xp includes advances broadcast driver architecture receiving capturing analog digital tv broadcasts complete signal demodulation tuning software de-multiplexing electronic program guide store ip data broadcasting etc addition windows xp media center edition introduced windows media center application pvr-like recording playback features tv content windows xp includes improved firewire ieee 1394 support dvcpro25 525-60 625-50 digital video cameras audio video devices introduces mstape wdm driver d-vhs mpeg camcorder devices windows xp sp2 adds support dvcpro50 dvcpro100 directshow 8 introduces video mixing renderer-7 vmr-7 filter uses directdraw 7 video rendering replacing overlay mixer vmr-7 mix multiple streams graphics alpha blending allowing applications draw text closed captions graphics channel logos ui buttons video without flickering support compositing implement custom effects transitions vmr-7 also supports source color keying overlay surface management frame-stepping improved multiple-monitor support vmr-7 features windowless mode applications easily host video playback within window renderless playback mode applications access composited image rendered directx 9 introduced vmr-9 uses direct3d 9 instead directdraw allowing developers transform video images using direct3d pixel shaders windows xp sp2 introduced yuv mixing mode vmr-7 vmr-9 renderers performs mixing yuv color space save memory bandwidth directshow 8 includes avstream multimedia class driver video-only audio-video kernel streaming windows xp provides new and/or improved drivers user interfaces devices compared windows 98 beginning windows xp service pack 1 generic usb 2.0 enhanced host controller interface drivers included windows xp also adds support usb device classes bluetooth usb video device class imaging still image capture device class media transfer protocol windows media player 10 mass storage devices windows xp introduces hardware descriptors distinguish various storage types operating system set appropriate default write caching policy example usb devices disables write caching default surprise removal devices cause data loss device manager provides configuration setting whether optimize devices quick removal performance windows xp supports twain well windows image acquisition-based scanners windows image acquisition windows xp adds support automatic document feeder scanners scroll-fed scanners without preview capabilities multi-page tiff generation wia video snapshot filter driver introduced allows still frames captured video stream windows xp sp1 later support downloadable wia library v2.0 provides access wia functionality programming languages scripting environments support ole automation scanner camera wizard based windows image acquisition common dialogs wia devices improved windows xp show media information metadata rotate images necessary categorize subfolders capture images video case still video camera crop scan images single multi-page tiff case scanner picture transfer protocol ptp implementation updated support mandatory optional commands ptp standard object tree support allows secondary files associated parent file grouped transferred concurrently windows media player 10 also adds media transfer protocol transferring media content portable devices thus digital cameras windows xp supports acquiring photos using either wia ptp usb mass storage class mtp protocols depending camera manufacturer supports windows xp includes technology roxio allows users directly burn files compact disc windows explorer previously end users install cd burning software windows xp cd dvd-ram fat32 dvd-ram burning directly integrated windows interface data discs created using joliet iso 9660 file systems audio cds using redbook standard prevent buffer underrun errors windows xp premasters complete image files burnt streams disc burner users burn files cd way write files floppy disk hard drive via standard copy-paste drag drop methods burning functionality also exposed api called image mastering api windows xp cd burning support disk-to-disk copying disk images although api used programmatically tasks creation audio cds integrated windows media player audio cds burnt using track-at-once mode cd-rw discs quick erased api support added windows xp burning dvds blu-ray discs mastered-style burning udf write-once rewritable dvd blu-ray media installing windows feature pack storage upgrades imapi version 2 note add dvd blu-ray burning features windows explorer third party applications use apis support dvd blu-ray burning windows xp includes firewire 800 support 1394b beginning service pack 1 mentioned section windows xp includes improved support firewire cameras audio video devices s/pdif audio mpeg-2 video streams supported across firewire audio video receivers set-top boxes dvd d-vhs speakers tv transmissions windows xp supports av/c iec 61883 protocol isochronous real-time data transfer audio-video applications windows xp also allows non-firewire devices exposed virtual firewire devices direct memory access 1394 bus host target allows kernel debugging firewire finally support tcp/ip networking internet connection sharing ieee 1394 bus windows xp includes windows script host 5.6 major update wsh environment includes improved object model reduce boilerplate code stronger security several improvements new xml-based file format windows script file format .wsf introduced besides .vbs .js store xml node file extra information besides script code digital signature blocks runtime directives instructions import external code wsf schema include jobs wrapped unique job tag outer package tag tags wsf file allow including external files importing constants tlb storing usage syntax runtime element displaying using new showusage method invoked switch wsf format also supports hosting multiple wsh scripting languages including cross function-calls wshshell object supports 'currentdirectory read-write method scripts digitally signed well verified programmatically using scripting.signer object script provided valid certificate present system alternatively signcode tool platform sdk extended support wsh filetypes may used command line verifyfile method used authenticate embedded signature validity check script modifications signing wsh thus decide whether execute script verification code stored in-memory string also signed using sign method signature block stored commented section script file backward compatibility older wsh versions using software restriction policies supported windows xp later system may also configured execute scripts digitally signed thus preventing execution untrusted scripts local scripts also run remote machine new wscript.wshcontroller object powered dcom remote wsh enabled group policy administrative template registry remote scripts always run wscript loaded remote machine server process run non-interactively default configured using dcomcnfg run security context allows display user interface wsh automation server loads instance wshremote object created script runs calling execute method external files called remote script must located remote machine directory path specified exec method remote script monitored using status property wsh 5.6 introduces exec method wshshell object execute command-line console applications access standard i/o streams stdin stdout stderr spawned process earlier versions windows script use arguments one access wsharguments collection object could created externally required person running script know order arguments syntax values wsh 5.6 introduces named arguments command line follow /string value boolean convention defined 'runtime tag recognized irrespective order command line named arguments grouped named collection object usual methods like item count length well exists method 'showusage method wsharguments object mentioned earlier shows argument information message box windows xp includes scriptpw.password com automation object implemented scriptpw.dll file used mask sensitive information like passwords command line scripts users log windows xp professional remotely remote desktop service built terminal services technology rdp similar remote assistance allows remote users access local resources printers terminal services client special remote desktop connection client web-based client using activex control may used connect remote desktop remote desktop clients earlier versions windows windows 95 windows 98 98 second edition windows windows nt 4.0 windows 2000 made available microsoft permits earlier versions windows connect windows xp system running remote desktop vice versa several resources users redirect remote server machine local client depending upon capabilities client software used instance file system redirection allows users use local files remote desktop within terminal session printer redirection allows users use local printer within terminal session would locally network shared printer port redirection allows applications running within terminal session access local serial parallel ports directly audio allows users run audio program remote desktop sound redirected local computer clipboard also shared remote computer local computer rdp client windows xp upgraded 7.0 remote desktop web connection component internet information services 5.1 also allows remote desktop functionality web activex control internet explorer remote assistance allows windows xp user temporarily take remote windows xp computer network internet resolve issues hassle system administrators personally visit affected computer remote assistance allows diagnose possibly even repair problems computer without ever personally visiting remote assistance allows sending invitations support person email windows messenger saving invitation file computer controlled support person connecting remotely well one sending invitation chat audio-video conversations file transfer available windows xp introduces fast user switching end user friendly welcome screen user account picture replaces classic logon prompt fast user switching allows another user log use system without log previous user quit applications previously windows windows 2000 one user time could logged except terminal services serious drawback multi-user activity fast user switching like terminal services requires system resources single user logged time although one user logged one user actively using account time feature available welcome screen turned joined windows server domain novell client installed even welcome screen enabled users switch classic logon pressing ctrl+alt+del twice welcome screen windows xp introduced windows installer msi 2.0 windows installer 2.0 brought major improvements installation management side-by-side clr assemblies sandboxing msi custom actions improved event logging hiding sensitive information log files per-user program isolation digital signatures improved patching robust patch conflict resolution reduced unnecessary unversioned file copying source prompts terminal server support integration system restore software restriction policies windows xp service pack 2 includes windows installer 3.0 also adds numerous improvements patching patch uninstallation support add remove programs binary delta patches patch sequencing install patches correct order installing multiple patches different products one transaction eliminating source media requests delta compression patches patch elevation limited user accounts msi source location list inventory management apis fixing numerous bugs windows xp sp3 includes msi 3.1v2 windows xp updated windows installer 4.5 windows disk defragmenter updated alleviate several restrictions longer relies windows nt cache manager prevented defragmenter moving pieces file cross 256kb boundary within file parts stream including cluster boundary non-compressed files reparse points bitmaps attribute_lists ntfs metadata files efs-encrypted files ntfs master file table defragmented defragmenter supports ntfs volumes cluster sizes larger 4 kilobytes command-line tool defrag.exe included providing access defragmenter cmd.exe task scheduler users members power users group schedule defragmentation windows task manager incorporates number improvements windows xp updated display process names longer 15 characters length processes tab used truncated windows 2000 session id user name columns added processes tab delete key also used terminate processes processes tab new networking tab shows statistics relating network adapters present computer default adapter name percentage network utilization link speed state network adapter shown along chart recent activity options shown choosing select columns ... view menu users tab shows users currently session computer server computers may several users connected computer using terminal services may also multiple users logged onto computer one time using fast user switching users disconnected logged tab shutdown menu introduced allows access standby hibernate turn restart log switch user holding codice_2 clicking new task opens command prompt windows xp includes new command-line tools wmi-based scripts windows 2000 ntlm hash user password requirement technically allowed potential malefactor decrypt master key ntlm hash directly security accounts manager database windows xp improves dpapi security encrypting master key using sha1 hash password also improves security data encrypted encrypting file system windows xp pki supports cross-certification bridge ca scenarios user -type certificates auto-enrolled renewed certificate requests issuing new certificates renewing expired ones pending administrator approval issued certificate authority approved install automatically root ca certificates also auto-update via microsoft update windows xp also supports delta crls crls whose status changed since last full base compiled crl base64-encoded crls revocation checking use default windows xp enroll version 2 certificate templates many configurable attributes smart cards used log terminal server sessions connecting windows server 2003 higher terminal server capicom system tools net.exe runas.exe also numerous improvements certificate status checking chain building revocation checking path validation discovery windows xp service pack 3 adds sha-2 hashing algorithms sha256 sha384 sha512 cryptoapi validating x.509 certificates windows xp includes several encrypting file system improvements notable improvement multiple user accounts share access encrypted files file-by-file basis details button advanced file attributes dialog file properties allows adding removing additional users access efs-encrypted file viewing certificate thumbprint data recovery agent account efs certificates autoenrolled ca support revocation checking certificates used sharing encrypted files unlike windows 2000 default local data recovery agent requirement one although self-signed certificate recovery agent generated using cipher.exe dpapi master key protected using domain-wide public key stronger fips 140-1 compliant algorithm 3des used windows xp service pack 1 adds support default use aes-256 symmetric encryption algorithm efs-encrypted files kb912761 windows xp sp2 windows xp sp3 users configure whether efs generates self-signed certificate certificate authority unavailable windows xp also warns user efs encrypted files copied file system fat unsupported location support efs thus file going get decrypted windows xp also encrypt files remote server ntfs server trusted delegation active directory user certificate private key loaded local profile server roaming user profile used copied locally webdav server mapped drive letter windows xp encrypt file locally transport raw encrypted file webdav server using http put command similarly efs encrypted files downloaded raw webdav decrypted locally command line utilities cipher copy xcopy updated windows xp efs also completely disabled windows xp group policy domain registry non-domain computer faster cache validation time long user session key certificate chain cached adjusted starting windows xp password reset disk created using forgotten password wizard disk used reset password using password reset wizard logon screen user rsa private key backed using offline public key whose matching private key stored one two places password reset disk computer member domain active directory member domain attacker authenticate windows xp localsystem still access decryption key stored pc hard drive password reset dpapi master key deleted windows xp blocks access efs encrypted files prevent offline rogue attacks protect encrypted files user changes password back original password efs encrypted files recovered windows xp prompts credentials upon authentication errors allows saving use integrated windows authentication secure roaming keyring store protected data protection api saved credentials managed stored user names passwords item user accounts control panel certificate authority present users select x.509 certificate prompted credentials resource accessed saved credentials used remote access/vpn connections also create temporary credentials keyring make experience seamless credential manager also exposes api single sign windows xp introduces software restriction policies safer api use software restriction policies system may configured execute install applications scripts digitally signed certain trust level thus preventing execution untrusted programs scripts administrators define default rule using local security policy snap-in exceptions rule types rules include hash rule path rule certificate rule zone rule identify file hash path software publisher certificate internet explorer-zone respectively example activex control restricted run particular domain specifying certificate rule-based software restriction policy windows xp service pack 2 introduced data execution prevention feature present nx evp amd amd64 processors xd edb intel processors flag certain parts memory containing data instead executable code prevents overflow errors resulting arbitrary code execution intended prevent application service executing code non-executable memory region helps prevent certain exploits store code via buffer overflow example dep runs two modes hardware-enforced dep cpus mark memory pages nonexecutable software-enforced dep limited prevention cpus hardware support software-enforced dep protect execution code data pages instead another type attack seh overwrite hardware-enforced dep enables nx bit compatible cpus automatic use pae kernel 32-bit windows native support 64-bit kernels software dep unrelated nx bit microsoft calls enforcement safe structured exception handling software dep/safeseh simply checks exception thrown make sure exception registered function table application requires program built dep enabled applications users gain additional resistance zero-day exploits applications dep-compliant generate dep exceptions therefore dep enforced applications default 32-bit versions windows turned critical system components however windows xp service pack 3 introduces additional nx apis allow software developers enable nx hardware protection code independent system-wide compatibility enforcement settings developers mark applications nx-compliant built allows protection enforced application installed runs enables higher percentage nx-protected code software ecosystem 32-bit platforms default system compatibility policy nx configured protect operating system components windows xp rtm introduced internet connection firewall later upgraded windows firewall windows xp service pack 2 support filtering ipv6 traffic well default windows firewall performs stateful packet filtering inbound solicited unsolicited traffic types network interfaces lan/wlan pppoe vpn dial-up connections like internet connection sharing firewall location-aware policy meaning disabled corporate domain enabled private home network option disallow exceptions may useful connecting public network firewall also used edge firewall ics clients firewall blocks program displays notification excepted traffic specified tcp/udp port application filename scope part network excepted traffic originates supports port mapping icmp security log capabilities included record ip addresses data relating connections originating home office network internet record dropped packets successful connections used instance track every time computer network connects website windows firewall also supports configuration group policy applications use windows firewall apis automatically add exceptions windows security center introduced windows xp service pack 2 provides users ability view status computer security settings services windows security center also continually monitors security settings informs user via pop-up notification balloon problem windows security center consists three major components control panel windows service application programming interface provided windows management instrumentation control panel divides monitored security settings categories headings displayed color-coded backgrounds current state settings determined windows service starts automatically computer starts takes responsibility continually monitoring system changes settings made available system wmi provider anti-malware firewall software vendors register security center wmi provider windows update settings status also monitored reported windows 2000 wireless support support seamless roaming auto-configuration windows xp wireless zero configuration service supports automatic wireless network configuration re-authentication necessary thus providing seamless roaming capability setting preferred order connections absence wireless access point windows xp set ad hoc wireless network native support wpa wpa2 authentication infrastructure networks latest service packs and/or updates applied windows xp includes wireless network setup wizard supports windows connect usb flash drive wcn-ufd method ease setting wireless network inexperienced users kb918997 windows xp sp2 windows xp sp3 add wireless lan api developers create wireless client programs manage profiles connections ieee 802.1x support wireless wired connections case pki available issue certificates vpn connection support preshared key ike authentication windows xp connect hotspots created using wireless provisioning services windows xp service pack 2 added native bluetooth support windows xp bluetooth stack supports external integrated bluetooth dongles attached usb windows xp sp2 sp3 support bluetooth 1.1 1.0 bluetooth 2.0 bluetooth 2.0+edr bluetooth stack supports following bluetooth profiles natively pan spp dun hid hcrp third-party stacks may replace windows xp stack may support profiles newer versions bluetooth windows xp internet connection sharing integrated upnp allowing remote discovery control ics host quality service packet scheduler component ics client relatively fast network ics host connected internet slow link windows may incorrectly calculate optimal tcp receive window size based speed link client ics host potentially affecting traffic sender adversely ics qos component sets tcp receive window size would receiver directly connected slow link internet connection sharing also includes local dns resolver windows xp provide name resolution network clients home network including non-windows-based network devices ics also location-aware connected domain computer group policy restrict use ics home ics enabled multiple applications accessing internet simultaneously without qos connection n't fast enough tcp receive window size set full window data transit first application uses connection steady state reached subsequent connections made applications take much longer reach optimal window size transmission rate second third application always lower application established connection first slow links qos component windows xp automatically enables deficit round robin scheduling scheme creates separate queue application services queues round-robin fashion basic production quality support windows xp ipv6 teredo tunneling advanced networking pack later incorporated windows xp sp2 ipv6 installed configured command line using netsh interface ipv6 context gui support network interface link-local address assigned stateless autoconfiguration local global addresses performed windows xp static ipv6 addresses assigned ipv6 router local link transition mechanisms manually configured tunnels 6to4 set windows firewall beginning windows xp sp2 also supports ipv6 stateful filtering applications tools telnet client ftp client ping nslookup tracert dns resolver file print sharing internet explorer iis updated support ipv6 privacy extensions enabled used default 6to4 automatically activated public ipv4 addresses without global ipv6 address types tunnels set include 6over4 teredo isatap portproxy teredo also helps traverse cone restricted nats teredo host-specific relay enabled global ipv6 address assigned otherwise teredo client functionality enabled windows xp dns resolver make dns queries using ipv4 use ipv6 transport make query however dns query sends back ipv4 ipv6 resource records ipv6 addresses preferred windows xp support dhcpv6 pppv6/ipv6cp open source dhcpv6 implementation called dibbler available although stateless autoconfiguration largely makes unnecessary windows xp includes background intelligent transfer service windows service facilitates prioritized throttled asynchronous transfer files machines using idle network bandwidth bits transfer data whenever bandwidth used applications example applications use 80 available bandwidth bits use remaining 20 bits constantly monitors network traffic increase decrease network traffic throttles transfers ensure foreground applications web browser get bandwidth need bits also supports resuming transfers case disruptions bits version 1.0 supports downloads version 1.5 bits supports downloads uploads uploads require iis web server bits server extension receiving side bits 2.0 part windows xp sp2 added support performing concurrent foreground downloads using server message block paths remote names downloading portions file changing prefix complete name remote name limiting client bandwidth usage bits upgradeable version 2.5 windows xp bits 2.5 part windows xp sp3 adds support ipv6 certificate-based client authentication secure http transports custom http headers windows xp components windows update use bits download updates idle bandwidth used download updates downloading resumed case network connectivity interrupted bits uses queue manage file transfers downloads files behalf requesting applications asynchronously i.e. application requests bits service transfer free job even terminate transfer continue background long network connection job owner logged bits supports transfers http https network application begins consume bandwidth bits decreases transfer rate preserve user interactive experience except foreground priority downloads bits exposed component object model com making possible use virtually programming language windows xp fax console manage incoming outgoing archived faxes settings fax monitor appears notification area fax transmission reception progress manual reception faxes enabled appears upon incoming fax call archived faxes open windows picture fax viewer tiff format upon installing microsoft outlook fax service automatically switches windows address book using outlook address book windows xp introduces fax service extended com api application developers incorporate fax functionality advanced networking pack later made part sp2 introduced peer-to-peer networking peer name resolution protocol pnrp windows xp operates ipv6 p2p architecture windows xp consists following components pnrp provides dynamic name publication resolution names endpoints pnrp distributed name resolution protocol allowing internet hosts publish peer names corresponding ipv6 addresses optionally information hosts resolve peer name retrieve corresponding addresses information establish peer-to-peer connections pnrp peer names composed authority qualifier authority identified secure hash associated public key place-holder number zero peer name unsecured qualifier string allowing authority different peer names different services peer name secure pnrp name records signed publishing authority verified using public key unsecured peer names published anybody without possible verification multiple entities publish peer name example peer name associated group group member publish addresses peer name peer names published resolved within specified scope scope local link site e.g campus whole internet graphing pnrp also allows creating overlay network called graph peer overlay network corresponds node graph nodes resolved addresses using pnrp nodes graph share book-keeping information responsible functioning network whole example distributed resource management network node resource needs shared information shared records flooded peers graph peer stores record local database record consists header body body contains data specific application using api header contains metadata describe data body name-value pairs serialized using xml addition author version information also contain index body data fast searching node connect nodes directly well communication need shared entire graph grouping peer-to-peer api also allows creation secure overlay network called group consisting subset nodes graph group shared multiple applications unlike graph peers group must identifiable unique named registered using pnrp digital signature certificate termed group member certificate gmc records exchanged digitally signed peers must invited group invitation contains gmc enables join group windows xp introduces simplified form sharing files local users multi-user environment network called simple file sharing simple file sharing enabled default non-domain joined computers disables separate security tab used set advanced acls/permissions enables common interface permissions file system folders sharing simple file sharing enabled documents folder subfolders read written owner local administrators shared network checking make folder private option properties local administrators also denied permissions documents folder sharing files user accounts computer simple file sharing enabled windows xp includes shared documents folder simple file sharing disables granular local network sharing permissions shares item everyone group network read write access without asking password forcing guest user permissions windows xp webdav mini-redirector added preferred old web folders client default newer client works system service network-redirector level immediately file-system allowing webdav shares assigned drive letter used software even firewalls nats applications open remote files http servers edit file save changes back file server allows redirector also allows webdav shares addressed via unc paths e.g codice_5 converted codice_6 compatibility windows filesystem apis webdav mini-redirector known limitations authentication support although windows xp ship following major windows features out-of-the-box new features added windows xp downloading components incorporated later versions windows
Operating systems
gall force origin precursor gall force franchise originally appearing monthly model graphix magazine japan 3d photo novel using detailed models later set stage animated films rabby patty rumy main solnoid characters featured equipped different uniforms weapons vehicles shown regular gall force ovas although first-ever storyline gall force mythos proper star front place official continuity questioned disregarded due contradictions eternal story although actual origin franchise seen fans non-canon alternate timeline another factor causes question fact fans outside japan never knew photo novel existence original timeline gall force series consist four story arcs first story arc rhea arc earth chapter arc new era arc within arc several episodes exception rhea first arc starts centuries-long war paranoids solnoids exodus early humanity planet terra death star leaf crew timeline ends events lead rhea arc first story arc consists three episodes gall force eternal story gall force 2 destruction gall force 3 stardust war rhea gall force takes place aftermath stardust war events earth chapter 21st century earthen discovery derelict alien technology moon—which fact remnants events eternal story —ignited arms race western eastern blocs rushed deploy technology weapons including form artificial life based paranoids mme artificial life turned humanity starting war extermination creators rhea plot summary year 2084 scientist grey newman found reverse-engineered technology solnoid ship found moon see eternal story unintentionally brought end civilization world war iii breaks middle battle human alien synthezoids turn creators nearly annihilating humankind later year 2085 remaining humans run machines terminating order survive defeat alien machines human race must leave earth go mars among voyagers one woman bears burden guilt father contribution destruction civilization earth chapter arc continues story rhea arc reincarnations star leaf crew completion operation exodus earth resistance must survive long enough arrival mars reinforcements led general mckenzie consists three episodes earth chapter 1 earth chapter 2 earth chapter 3 new era concludes story earth chapter takes place 200 years later consists two episodes new era plot summary centuries war humans mme machines humans battle however many lives lost earth rendered terribly damaged unstable live shortly afterwards mankind began restore earth new race cyborgs called yumans begun live humans desire better future humanity linked one large computer network however conflict humans yumans shortly began considering far better human yumans began plot takeover humanity lives separated tightly packed arcologies built around world keeping minimal contact dealing internal problems like overpopulation young scientist named nova influenced revolutionary leader yumans genova develops plans bring humanity using tools acquired years awakens artificial intelligence destroy human life reprograming every computer earth gorn virus virus actually bit nova predicted due intent wiping humans yumans solar system entire system connected wars gorn able bring presence everywhere attempt achieve long-term goals gorn plans surprise catty foreseen disaster sets plan motion virus strikes yuman heart leads force seven women final battle man machine 1996 ova reimagining series replaced amorphous paranoids seemingly endless civil war west force east force solnoid armies unlike previous ovas somber apocalyptic tones revolution traditional sci-fi adventure story although still stresses tragedies wide-scale destruction caused war four episodes produced along one soundtrack album vocal collection starring main female cast singing various songs one remake disguised spies one original saga soundtracks plot tells struggle west force east force armies solnoids threatens escalate total destruction solnoid race sides search ultimate war weapon anti-matter gun happenstance however several troopers east force eluza rabby patty rumy west force lufy encounter conch outlawed solnoid anti-war organization trying spread peace among hostile parties discover war merely used insidious instrument balance one singular solnoid party rogue solnoid troopers unwittingly find fighting idea completely alien presents way stopping perpetuated madness 1988 omake animated mockumentary detailing behind-the-scenes look production gall force eternal story destruction first story arc characters drawn super deformed versions eternal story counterparts video maintained comedic tone opposed somewhat serious war story original video supposedly documenting ten little gall force released along scramble wars united states animeigo single vhs video titled super-deformed double feature strangely time released dvd gall force titles vhs release much-sought rare collector items shoot 'em released japan simply titled gall force family computer disk system hal laboratory november 19 1986 another shoot-em-up also developed hal released year titled gall force defense chaos msx followed gall force eternal story graphic adventure game msx2 1987 similarly ovas era studios aic artmic gall force features huge amount music performed voice actors involved series several soundtracks released film ova ova episode earth chapter case addition many music collections released featuring original songs performed aforementioned voice actors along various singles cd drama far soundtracks released films destruction stardust war soundtracks singles music collections gall force earth saga back school wars
Computer architecture
oberon programming language oberon general-purpose programming language created 1986 niklaus wirth latest member wirthian family algol-like languages euler algol-w pascal modula modula-2 oberon result concentrated effort increase power modula-2 direct successor pascal simultaneously reduce complexity principal new feature concept type extension record types permits construction new data types basis existing ones relate deviating dogma strictly static data typing type extension wirth way inheritance reflecting viewpoint parent site oberon developed part implementation oberon operating system eth zurich switzerland name moon uranus oberon oberon still maintained wirth latest language change dated may 8 2016 oberon designed motto attributed albert einstein mind “ make things simple possible simpler. ” principal guideline concentrate features basic essential omit ephemeral issues another factor recognition growth complexity languages c++ ada contrast oberon emphasizes use library concept extending language enumeration subrange types present modula-2 removed similarly set types limited small sets integers number low-level facilities sharply reduced particularly type transfer functions eliminated elimination remaining potentially-unsafe facilities concludes essential step toward obtaining truly high-level language close type-checking even across modules strict index-checking run time null-pointer checking safe type extension concept largely allow programmer rely language rules alone intent strategy produce language easier learn simpler implement efficient oberon compilers viewed compact fast providing adequate code quality compared commercial compilers following features characterize oberon language oberon supports extension record types construction abstractions heterogeneous structures contrast later dialects—oberon-2 active oberon—the original oberon n't dispatch mechanism language feature rather programming technique design pattern gives great flexibility oop world oberon operating system two programming techniques used conjunction dispatch call method suite message handler technique table procedure variables defined global variable type declared extended module assigned back generic module extend generic type figure specific shape dynamic dispatch done via procedures figures module generic module technique consists replacing set methods single procedure discriminates among various methods extend generic type figure specific shape oberon operating system techniques used dynamic dispatch first one used known set methods second used new methods declared extension module example extension module rectangles implement new rotate procedure within figures module could called via message handler no-cost implementations oberon language oberon operating system found internet several ethz changes made first released specification object-oriented programming features added 'for loop reinstated instance result oberon-2 currently common implementation release called native oberon includes operating system directly boot pc class hardware .net implementation oberon addition minor .net-related extensions also developed ethz 1993 ethz spin company brought dialect oberon-2 market name oberon-l renamed component pascal 1997 oberon-2 compilers maintained eth include versions microsoft windows linux solaris classic mac os furthermore implementations various operating systems atari-tos amigaos oberon-2 lex scanner yacc parser stephen j bevan manchester university uk based one mössenböck wirth reference version 1.4 also oxford oberon-2 compiler also understands oberon-07 vishap oberon latter based josef templ oberon c transpiler called ofront turn based op2 compiler developed regis crelier ethz oberon-07 defined niklaus wirth 2007 revised 2011 2013 2014 2015 2016 based original version oberon rather oberon-2 main changes explicit numeric conversion functions e.g floor flt must used loop exit statements eliminated statements extended case statements used type extension tests return statements connected end function imported variables structured value parameters read-only arrays assigned without using copy full details see programming language oberon-07 oberon-07 compilers developed use several different computer systems wirth compiler targets risc processor design used implement 2013 version project oberon operating system xilinx fpga spartan-3 board ports risc processor fpga spartan-6 spartan-7 artix-7 risc emulator windows compilable linux os x well binaries available windows also exist obnc compiles via c used posix compatible operating system commercial astrobe implementation targets 32-bit arm cortex-m3 m4 m7 microcontrollers patchouli compiler produces 64-bit windows binaries oberon-07m produces 32-bit windows binaries implements revision 2008 language akron produces binaries windows linux oberonjs translates oberon javascript oberonc implementation java virtual machine active oberon yet another variant oberon adds objects object-centered access protection local activity control system-guarded assertions preemptive priority scheduling changed syntax methods type-bound procedures oberon world objects may active means may threads processes additionally active oberon way implement operators including overloading advanced syntax using arrays see oberonx language extensions proceedings 7th joint modular languages conference 2006 oxford uk knows namespaces see proposal module contexts operating system a2 bluebottle especially kernel synchronizes coordinates different active objects ethz released active oberon supports active objects bluebottle operating system environment jdk http ftp etc language many prior designs ethz versions available download internet written single dual x86 cpus strongarm family supported development continued languages family extension oberon-2 originally named oberon/l later renamed component pascal developed windows classic mac os oberon microsystems commercial company spin-off ethz .net queensland university technology addition lagoona obliq languages carry oberon spirit specialized areas recent .net development efforts ethz focused new language called zonnon includes features oberon restores pascal enumerated types built-in io syntactic differences additional features include support active objects operator overloading exception handling zonnon available plug-in language microsoft visual studio .net development environment oberon-v originally called seneca seneca younger descendant oberon designed numerical applications supercomputers especially vector pipelined architectures includes array constructors statement see seneca language numerical applications vectorcomputers proc conpar 90 vapp iv conf r. griesemer diss nr 10277 eth zurich
Programming language topics
nokia c5-00 nokia c5-00 first new cseries nokia phones announced march 2010 c5-00 smartphone messaging social networking features including example facebook flickr applications c5-00 allows multitasking display 3.2-megapixel camera c5-00.2 5 mp also includes gps free navigation courtesy ovi maps runs symbian os s60 3rd edition feature pack 2 microsd slot support 16-gigabyte cards c5-00.2 32 gb – nokia c5 comes two-gigabyte card box device dimensions thin across high battery life good 12 hours talk time gsm working memory ram 128 mb c5-00.2 256 mb available white warm grey nokia c5-00 made globally available second quarter 2010 c5-00 comes monoblock form factor weighs battery 5-way navi-key two soft keys separate call end clear application keys well volume keys side phone user interface ring tones customized announced maximum talk time varies 4.9 hours 3g networks 12 hours plain gsm networks maximum standby times 630 670 hours respectively music played maximum 34 hours phone offline mode phone features bluetooth connectivity 3.5 mm av connector stereo fm radio act data modem supports calendar contact synchronization microsoft outlook charged via usb conference calls three participants also made nokia c5-00 also features integrated web browser supports xhtml markup language flash lite 3.0 video streaming rss feeds camera back flash announced operating range 1.5 meters camera different capture colour tone scene white balance modes horizontal orientation also photo editor device video captured long memory available device also features secondary vga resolution camera video calls nokia c5-00.2 2011 comes 5-megapixel camera 256 mb ram support 32-gigabyte cards
Operating systems
shiftspace shiftspace discontinued open-source metaweb web annotation application framework allows altering web pages different tools tagline application open source layer web page implemented userscript greasemonkey extension firefox development shiftspace ceased 2011 shiftspace user viewing webpage least one shift notice small shiftspace notifier icon bottom left corner browser window pressing shift space keys user invokes meta layer particular page additional user-created content becomes visible shiftspace user invoke meta layer web page browse create additional interpretations contextualizations interventions called shifts available tools authoring shifts called spaces currently included core release notes highlights imageswap sourceshift spaces utilitarian like notes highlights interventionist like imageswap sourceshift shiftspace founded 2006 dan phiffer mushon zer-aviv students nyu interactive telecommunications program later year received prixars honorary mention next idea category ars electronica center shiftspace covered techcrunch cnet shiftspace supported grant swiss confederation commission rhizome.org
Web technology
data curation data curation organization integration data collected various sources involves annotation publication presentation data value data maintained time data remains available reuse preservation data curation includes processes needed principled controlled data creation maintenance management together capacity add value data science data curation may indicate process extraction important information scientific texts research articles experts converted electronic format entry biological database modern era big data curation data become prominent particularly software processing high volume complex data systems term also used historical uses humanities increasing cultural scholarly data digital humanities projects requires expertise analytical practices data curation broad terms curation means range activities processes done create manage maintain validate component specifically data curation attempt determine information worth saving long user rather database typically initiates data curation maintains metadata according university illinois graduate school library information science data curation active on-going management data lifecycle interest usefulness scholarship science education curation activities enable data discovery retrieval maintain quality add value provide re-use time data curation workflow distinct data quality management data protection lifecycle management data movement census data available tabulated punch card form since early 20th century electronic since 1960s inter-university consortium political social research icpsr web site marks 1962 date first survey data archive deep background data libraries appeared 1982 issue illinois journal library trends historical background data archive movement see social scientific information needs numeric data evolution international data archive infrastructure exact curation process undertaken within organisation depends volume data much noise data contains expected future use data means dissemination crises space data led 1999 creation open archival information system oais model stewarded consultative committee space data systems ccsds formed 1982 term data curation sometimes used context biological databases specific biological information firstly obtained range research articles stored within specific category database instance information anti-depressant drugs obtained various sources checking whether available database saved drug database anti-depressive category enterprises also utilizing data curation within operational strategic processes ensure data quality accuracy dissemination information packages dips information reuse dipir project studying research data produced used quantitative social scientists archaeologists zoologists intended audience researchers use secondary data digital curators digital repository managers data center staff others collect manage store digital information protein data bank established 1971 brookhaven national laboratory grown global project database three-dimensional structural data proteins large biological molecules pdb contains 120,000 structures standardized validated experimental data annotated flybase primary repository genetic molecular data insect family drosophilidae dates back 1992 flybase annotates entire drosophila melanogaster genome linguistic data consortium data repository linguistic data dating back 1992 sloan digital sky survey began surveying night sky 2000 computer scientist jim gray working data architecture sdss championed idea data curation sciences datanet research program u.s. national science foundation office cyberinfrastructure funding data management projects sciences dataone data observation network earth one projects funded datanet helping environmental science community preserve share data
Databases
cups cmu carnegie mellon university usable privacy security laboratory cups established spring 2004 bring together carnegie mellon university researchers working diverse set projects related understanding improving usability privacy security software systems privacy security research community become increasingly aware usability problems severely impact effectiveness mechanisms designed provide security privacy software systems indeed one four grand research challenges information security assurance identified computing research association 2003 give end-users security controls understand privacy control dynamic pervasive computing environments future challenge cups strives address cups affiliated carnegie mellon cylab members engineering public policy department school computer science electrical computer engineering department heinz college department social decision sciences
Computer security
morphological pattern morphological pattern set associations and/or operations build various forms lexeme possibly inflection agglutination compounding derivation term used domain lexicons morphology important distinguish paradigm lexeme morphological pattern context inflecting language inflectional morphological pattern explicit list inflected forms morphological pattern usually references prototypical class inflectional forms e.g ring per sing contrast paradigm lexeme explicit list inflected forms given lexeme e.g ring rang rung said terms difference description intension morphological pattern description extension paradigm
Computational linguistics
phox automated theorem proving phox proof assistant based higher-order logic extensible user gives phox initial goal guides subgoals evidence prove goal internally constructs natural deduction trees previously proven formula become rule later proofs phox originally designed implemented christophe raffalli ocaml programming language continued lead current development team joint effort university savoy primary aim phox project creating user friendly proof checker using type system developed jean-louis krivine university paris vii meant intuitive systems remaining extensible efficient expressive compared systems proof-building syntax simplified closer natural language features include gui-driven proof construction rendering formatted output proof correctness programs ml programming language phox currently used teach logic savoy university experimental usable state released cecill 2.0
Programming language topics
hardware architect hardware systems architect hardware architect responsible large systems architecture developed way handle systems large one person conceive let alone design systems size rapidly becoming norm architectural approaches architects increasingly needed solve problems large systems engineers group reputation understanding responding human needs comfortably developing humanly functional aesthetically pleasing products architects expected understand human needs develop humanly functional aesthetically pleasing products good architect translator user/sponsor engineers—and even among engineers different specialties good architect also principal keeper user vision end product—and process deriving requirements implementing vision determining users/sponsors actually want rather say want engineering—it art architect follow exact procedure s/he communicates users/sponsors highly interactive way—together extract true requirements necessary engineered system hardware architect must remain constantly communication end users systems architect therefore architect must familiar user environment problem engineer need knowledgeable potential engineering solution space user/sponsor view architect user representative provide input architect direct interaction project engineers generally discouraged chance mutual misunderstanding high user requirements specification joint product user hardware architect systems hardware architects user brings needs wish list architect brings knowledge likely prove doable within cost time constraints user needs translated set high level requirements also best time write first version acceptance test thereafter religiously kept date requirements way user absolutely clear s/he getting also safeguard untestable requirements misunderstandings requirements creep development first level hardware engineering requirements purely analytical exercise also involve hardware architect engineer compromises made—to meet constraints like cost schedule power space architect must ensure final product overall look feel stray far user intent engineer focus developing design optimizes constraints ensures workable reliable product architect primarily concerned comfort usability product engineer primarily concerned producibility utility product provision needed services user true function engineered system however systems become ever larger complex emphases move away simple hardware components narrow application traditional hardware development principles found insufficient—the application general principles hardware architecture design sub systems seen needed hardware architecture also simplified model finished end product—its primary function define hardware components relationships whole seen consistent complete correct representation user mind—especially computer–human interface also used ensure components fit together relate desired way necessary distinguish architecture user world engineered hardware architecture former represents addresses problems solutions user world principally captured computer–human interfaces chi engineered system engineered system represents engineering solutions—how engineer proposes develop and/or select combine components technical infrastructure support chi absence architect unfortunate tendency confuse two architectures since engineer thinks terms hardware user may thinking terms solving problem getting people point point b reasonable amount time reasonable expenditure energy getting needed information customers staff hardware architect expected combine knowledge architecture user world potentially useful hardware engineering architectures former joint activity user latter joint activity engineers product set high level requirements reflecting user requirements used engineers develop hardware systems design requirements requirements evolve course project especially long one architect needed hardware system accepted user architect best insurance changes interpretations made course development compromise user viewpoint hardware engineers specialists know applications hardware design development intimately apply knowledge practical situations—that solve real world problems evaluate cost–benefits various solutions within hardware specialty ensure correct operation whatever design hardware architects generalists expected experts one hardware technology approach expected knowledgeable many able judge applicability specific situations also apply knowledge practical situations evaluate cost/benefits various solutions using different hardware technologies example specially developed versus commercially available hardware components assure system whole performs according user expectations many commercial-off-the-shelf already developed hardware components may selected independently according constraints cost response throughput etc cases architect already assemble end system unaided s/he may still need help hardware engineer select components design build special purpose function architects engineers may also enlist aid specialists—in safety security communications special purpose hardware graphics human factors test evaluation quality control rma interface management etc effective hardware architectural team must immediate access specialists critical specialties architect planning building works overall design making sure pleasing useful inhabitants single architect may enough build single-family house many engineers may needed addition solve detailed problems arise novel high-rise building designed job large complex enough parts architecture may designed components building housing complex may one architect complex one type building part architectural team large hardware systems also require architect much engineering talent engineered system large complex enough chief hardware systems architect may defer subordinate architects parts job although may members joint architectural team architect must never viewed engineering supervisor architect sub-allocate hardware requirements major components subsystems within scope single hardware engineer engineering manager subordinate architect ideally hardware component/subsystem sufficiently stand-alone object tested complete component separate whole using simple testbed supply simulated inputs record outputs necessary know air traffic control system works order design build data management subsystem necessary know constraints subsystem expected operate good architect ensures system however complex built upon relatively simple clean concepts sub system layer—easily understandable everyone especially user without special training architect use minimum rules ensure partition well-defined clean kludges work-arounds short-cuts confusing detail exceptions user needs evolve system fielded use lot easier subsequently evolve simple concept one laden exceptions special cases lots fine print layering hardware architecture important keeping sufficiently simple layer remains comprehensible single mind layers ascended whole systems lower layers become simple components higher layers may disappear altogether highest layers acceptance test always remains principal responsibility architect chief means architect prove user hardware originally planned subordinate architects engineers met objectives large projects tend dynamic changes along way needed user e.g. problems change expected user e.g. cost schedule reasons acceptance tests must kept current times principal means user kept informed final product perform act principal goal towards subordinate personnel must design build test building architect uses sketches models drawings hardware systems architect use sketches models prototypes discuss different solutions results user system architect engineers subordinate architects early draft version user manual invaluable especially conjunction prototype set engineering requirements means communicating users explicitly avoided well written set requirements specification intelligible engineering fraternity much legal contract lawyers
Computer architecture
southbridge computing southbridge one two chips core logic chipset personal computer pc motherboard northbridge southbridge typically implements slower capabilities motherboard northbridge/southbridge chipset computer architecture systems intel chipsets southbridge named i/o controller hub ich amd named southbridge fusion controller hub fch since introduction fusion amd accelerated processing unit apu southbridge usually distinguished northbridge directly connected cpu rather northbridge ties southbridge cpu use controller integrated channel circuitry northbridge directly link signals i/o units cpu data control access due push system-on-chip soc processors modern devices increasingly northbridge integrated cpu die examples intel sandy bridge amd fusion processors released 2011 southbridge became redundant replaced platform controller hub pch architecture introduced intel 5 series chipset 2008 southbridge features remaining i/o functions managed pch directly connected cpu via direct media interface dmi southbridge chipset handled computer i/o functions usb audio serial system bios isa bus interrupt controller ide channels different combinations southbridge northbridge chips possible two kinds chips must designed work together industry-wide standard interoperability different core logic chipset designs traditionally interface northbridge southbridge pci bus main bridging interfaces used dmi intel umi amd name derived representing architecture fashion map first described introduction pci local bus architecture 1991 intel authors pci specification viewed pci local bus centre pc platform architecture i.e. equator northbridge extends north pci bus backbone support cpu memory/cache performance-critical capabilities likewise southbridge extends south pci bus backbone bridges less performance-critical i/o capabilities disk interface audio etc cpu located top map due north cpu connected chipset via fast bridge northbridge located north system devices drawn northbridge connected rest chipset via slow bridge southbridge located south system devices drawn although current pc platform architecture replaced pci bus backbone faster i/o backbones bridge naming convention remains functionality found contemporary southbridge includes optionally southbridge also includes support ethernet raid usb audio codec firewire support provided non-usb keyboard mouse serial ports machine normally device referred super i/o still rarely southbridge may directly support keyboard mouse serial ports
Computer architecture
joint battlespace infosphere joint battlespace infosphere project funded afrl air force research lab intended provide management network-centric warfare systems utilize gig global information grid
Distributed computing architecture
operating system advocacy operating system advocacy practice attempting increase awareness improve perception computer operating system motivation behind may increase number users system assert superiority one choice another brand loyalty pride operating system abilities open source operating systems political philosophical reasons persuade software vendors port specific applications device drivers computing platform generally done support increasing network effects platform operating system advocacy vary widely tone form seriously studied researched comparisons heated debates mailing lists forums advocates often normal users devote spare time advocacy operating system choice many deep abiding interest use design construction operating systems emotional investment favorite operating system one specific example known platform evangelism operating system advocacy compared advocacy fields particularly browser editor wars programming languages video game consoles well ford vs. chevy similar debates car culture due often emotional nature advocacy debate sometimes narrow appeal wider user population forums discussion advocacy often separate general discussion usenet comp.os comp.sys hierarchy often *.advocacy groups devoted exclusively advocating respective operating systems groups comp.sys.amiga.advocacy remain active even subject os ceases market force guide windows newsgroups exhorts usenet posters get involved arguments windows vs. os/2 vs. macintosh vs. nextstep except comp.os.ms-windows.advocacy group operating system advocacy discussions usenet elsewhere spawned variety jargon describing commonly seen behaviour including microdroid amiga persecution complex emotional form negative characteristics often associated operating system advocacy led create guidelines explaining consider positive advocacy linux advocacy guidelines guidelines effective os/2 advocacy freebsd served mailing list specifically advocacy discussion advocacy-related materials links provided freebsd website including page logos large number linux distributions many organizations involved linux advocacy including companies directly involved development distributions well purely advocacy-based groups seul promotion takes wide variety forms tux plush toys t-shirts posters even unorthodox forms body paints video games 1984 super bowl advertisement test drive macintosh apple switch get mac advertising campaigns apple computer long history advocating platform traditional media also covers advocacy macintosh hardware peripherals even lifestyle choices fans company projecting alternately hip entertaining liberating lifestyle negatively portraying microsoft windows ibm competitors anything awkward dated totalitarian sinister big brother figure neowin.net wrote editorials opposing windows-bashing media microsoft attempted boost popularity windows 7 launch party program like freebsd netbsd foundation hosts mailing list especially advocacy mailing list automatically archived made accessible online also provide official advocacy material posters flyers official powered logo license permitting use product running netbsd like freebsd netbsd openbsd project provides mailing list specifically intended advocacy advocacy openbsd.org created july 21 1998 discussion user groups stickers shirts promotion openbsd image also host flame-worthy discussions part advocacy project also maintains list consulting firms individual consultants around world website produced number slogans including free functional secure secure default power security flexibility openbsd release features original song variety artwork team os/2 grassroots organization conceived ibm employee initially joined ibmers quickly spread outside ibm whether ibm employees team os/2 members initially volunteered time passion without official sanction connection ibm members would promote os/2 trade shows conferences fairs stores participate operating system discussions compuserve prodigy fidonet usenet throw parties help users install os/2 contact media figures explain os/2 generate interest general exercise creativity initiative helping popularize os/2 industry dynamics gave rise passionate advocacy multi-faceted perhaps leading cause antipathy idea microsoft could would establish monopoly windows dos widely deemed far inferior os/2 additionally many users feared ibm proven eminently capable developing superior pc operating system knew little consumer marketing high-tech marketplace establishing even superior product standard cut-throat get-there-first-at-any-cost arena dominated microsoft finally mere fact many copies windows shipping users os/2 advocates viewed uncritical uninformed coupled fact many industry much riding success os/2 created conditions ripe many trying take matters hands spark needed combustible situation ignite example evangelism provided new ibm employees took empowerment seriously able coordinate efforts participation teamos2 forum internal ibm discussion group passionate supporters outside ibm adopted ideas modeled behaviors early activists within ibm
Operating systems
feedback loop email feedback loop fbl sometimes called complaint feedback loop inter-organizational form feedback mailbox provider mp forwards complaints originating users sender organizations mps receive users complaints placing report spam buttons webmail pages email client via help desks message sender organization often email service provider come agreement mp want collect users complaints feedback loops one ways reporting spam whether provide fbl choice mp end users report abuse mailbox provider reporting hub also help filtering alternative competent users may send abuse complaints directly acting mailbox providers marketers striving mail delivered twofold advantage remove subscribers n't want receive kind advertising listwashing analyze complaint rate hence advertising meets market expectations unsubscribing users complain marketers reduce overall complaint rate per ip domain ensuring targeted mail much likely reach subscribers actually want receive esps playing sender role sensitive sending mail behalf customers may affect reputation monitoring complaint rate one ways control users sending weakness fbl relative asynchrony produce glitches possibly large time interval sits esp subscription fbl recipient clicking junk button interval click actual deletion recipient name list much shorter may noteworthy case huge mailbox providers gmail aol bulk messages provide information unsubscribe directly header fields codice_1 codice_2 besides providing direct better way unsubscribe also allows tell apart unsubscription junk reporting example one report message posted discussion list junk staying subscribed sketched process implies spencer besides author sender message connected postmaster responsible mail domain subscribing fbl usually involves postmaster authorization fbl subscriber may may forward abuse reports relevant authors subscribers exist given mail domain isaac omit sending abuse report fact subscriptions done one one laborious task mail domains engaged mass mailing may want skip addresses latter shortcoming proposing auto-subscribe just-in-time fbls started sending unsolicited abuse report directives minimum way unsubscribe ipsos noted majority respondents survey spam reporting marked messages spam based solely subject sender data years end users told trust email unsubscribe links many users hit spam button alternative unsubscribing consequently report spam may act unsubscribe cases one reasons hit unsubscribe links avoid confirming message received opened abuse reporting format arf standard format fbl reports much like bounce messages whose design inherited arf abuse report consists human readable part followed machine readable part original message report characterized feedback-type field whose values may indicate one abuse fraud virus types registered iana microsoft use name junk mail reporting jmr also use format google gmail beta testing non-traditional fbl select esps gmail uses format—an aggregate report reveals spam rate per notable sender sendgrid reports gmail fbl developed launched julian tempelsman sri somanchi effective identifying spam anti-spam systems miss
Computer security
attack surface attack surface software environment sum different points attack vectors unauthorized user attacker try enter data extract data environment keeping attack surface small possible basic security measure examples attack vectors include user input fields protocols interfaces services due increase countless potential vulnerable points enterprise increasing advantage hackers attackers need find one vulnerable point succeed attack three steps towards understanding visualizing attack surface step 1 visualize visualize system enterprise first step mapping devices paths networks step 2 find indicators exposures second step correspond indicator vulnerability potentially exposed visualized map last step one ioe missing security controls systems software step 3 find indicators compromise indicator attack already succeeded one approach improving information security reduce attack surface system software basic strategies attack surface reduction include following reduce amount code running reduce entry points available untrusted users eliminate services requested relatively users less code available unauthorized actors tend fewer failures turning unnecessary functionality fewer security risks although attack surface reduction helps prevent security failures mitigate amount damage attacker could inflict vulnerability found
Computer security
aurora generator test idaho national laboratory ran aurora generator test 2007 demonstrate cyberattack could destroy physical components electric grid experiment used computer program rapidly open close diesel generator circuit breakers phase rest grid cause explode vulnerability referred aurora vulnerability vulnerability especially concern much grid equipment supports using modbus legacy communications protocols designed without security mind n't support authentication confidentiality replay protection means attacker communicate device control use aurora vulnerability destroy prepare experiment researchers procured installed 2.25 mw generator connected substation also needed access programmable digital relay another device controls breaker access could mechanical digital interface experiment researchers used cyberattack open close breakers sync maximize stress time breakers closed torque synchronization caused generator bounce shake eventually causing parts generator ripped apart sent flying parts generator landed far 80 feet away generator unit destroyed roughly three minutes however researchers assessed damage iteration attack real attack could destroyed unit much quickly experiment designated unclassified official use september 27 2007 cnn published article based information video dhs released july 3 2014 dhs released many documents related experiment part unrelated foia request aurora vulnerability caused out-of-sync closing protective relays close imperfect analogy would imagine effect shifting car reverse driven highway effect revving engine car neutral shifting drive aurora attack designed open circuit breaker wait system generator slip synchronism reclose breaker protection system recognizes responds attack ... traditional generator protection elements typically actuate block reclosing 15 cycles many variables affect time every system needs analyzed determine specific vulnerability aurora attack ... although main focus aurora attack potential 15-cycle window opportunity immediately target breaker opened overriding issue fast generator moves away system synchronism failure even single generator could cause widespread outages possibly cascading failure entire power grid occurred northeast blackout 2003 additionally even outages removal single component n-1 resilience large window second attack failure could take year replace destroyed generator many generators transformers custom-built aurora vulnerability mitigated preventing out-of-phase opening closing breakers suggested methods include adding functionality protective relays ensure synchronism adding time delay closing breakers one mitigation technique add synchronism-check function protective relays potentially connect two systems together implement function must prevent relay closing unless voltage frequency within pre-set range devices ieee 25 sync check relay well ieee 46,47,50 53 used prevent out-of-phase opening closing breakers discussion whether aurora hardware mitigation devices hmd cause failures may 2011 quanta technology published article used rtds real time digital simulator testing examine performance multiple commercial relay devices available aurora hmds quote relays subject different test categories find performance dependable need operate secure response typical power system transients faults power swing load switching ... general technical shortcomings protection scheme ’ design identified documented using real time testing results rtds testing showed yet single solution widely applied case present required reliability level presentation quanta technology dominion succinctly stated reliability assessment hmds dependable secure joe weiss cybersecurity control system professional disputed findings report claimed misled utilities wrote report done great deal damage implying aurora mitigation devices cause grid issues several utilities used quanta report basis installing aurora mitigation devices unfortunately report several questionable assumptions include applying initial conditions hardware mitigation designed address slower developing faults nominal grid frequencies existing protection address “ slower ” developing faults nominal grid frequencies 59 hz 61 hz aurora hardware mitigation devices fast out-of-phase condition faults currently gaps protection i.e. protected device grid march 4 2007 idaho national laboratory demonstrated aurora vulnerability june 21 2007 nerc notified industry aurora vulnerability september 27 2007 cnn released previously-classified demonstration video aurora attack homepage video downloaded october 13 2010 nerc released recommendation industry aurora vulnerability july 3 2014 us department homeland security released 840 pages documents related aurora
Computer security
fuse services framework fuse services framework open source soap rest web services platform based apache cxf use enterprise organizations productized supported fuse group fusesource corp. fuse services framework service-enables new existing systems use enterprise soa infrastructure fuse services framework pluggable small-footprint engine creates high performance secure robust services minutes using front-end programming apis like jax-ws jax-rs supports multiple transports bindings extensible developers add bindings additional message formats systems work together without communicate centralized server fuse services framework part red hat jboss fuse fabric8 free apache 2.0 licensed upstream community jboss fuse product red hat
Web technology
openlldp openlldp project aims bring comprehensive implementation ieee standard 802.1ab link layer discovery protocol openlldp currently supports lldp transmission reception following platforms
Internet protocols
homeos homeos working title home automation operating system developed microsoft research early 2010s microsoft research announced project 2010 homeos communicates lab things cloud-based internet things infrastructure also developed microsoft slogan homeos project enabling smarter homes everyone homeos development team written three sample applications make use multiple devices including sticky media app plays music parts house lit rooms two-factor authentication app uses audio smartphones images front-door camera turn lights user identified home browser viewing controlling user access devices home staff worked homeos project cited microsoft ceo steve ballmer focus enterprise applications productivity software cloud computing reason stalled development homeos
Operating systems
james pustejovsky pustejovsky proposed generative lexicon theory lexical semantics interests include temporal reasoning event semantics spatial language language annotation computational linguistics machine learning pustejovsky research group current projects include timeml iso-space projects timeml project standard markup language temporal events document recently adopted iso-timeml iso iso-space iso-directed effort create expressive specification representation spatial information language previous work included medstract project effort extract information medical documents using current natural language processing technology
Computational linguistics
object request broker distributed computing object request broker orb middleware allows program calls made one computer another via computer network providing location transparency remote procedure calls orbs promote interoperability distributed object systems enabling systems built piecing together objects different vendors different parts communicate via orb orbs handle transformation in-process data structures raw byte sequence transmitted network called marshalling serialization addition marshalling data orbs often expose many features distributed transactions directory services real-time scheduling orbs corba-compliant systems use interface description language describe data transmitted remote calls object-oriented languages orb actually provides framework enables remote objects used network way local part process client side so-called stub objects created invoked serving part visible used inside client application stub methods invoked client-side orb performs marshalling invocation data forwards request server-side orb server side orb locates targeted object executes requested operation returns results results available client orb performs demarshalling passes results back invoked stub making available client application whole process transparent resulting remote objects appearing local
Distributed computing architecture
stos basic stos basic dialect basic programming language implemented atari st computer stos basic originally developed jawx françois lionet constantin sotiropoulos published mandarin software known europress software stos basic version basic designed creating games set powerful high-level graphics sound commands offered made suitable developing multimedia-intense software without knowledge internals atari st although first version stos released uk version 2.3 released late 1988 mandarin software version released earlier france version 2.3 bundled three complete games orbit zoltar bullet train many accessories utilities sprite music editors compiler soon released enabled user compile stos basic program executable file ran lot faster compiled rather interpreted order compatible compiler stos needed upgraded version 2.4 came compiler stos 2.4 also fixed bugs faster floating point mathematics code floating point numbers smaller range stos 2.5 released make stos run atari stes tos 1.06 1.6 stos 2.6 needed make stos run atari stes tos 1.62 stos 2.7 compiler-only upgrade made programs stos tracker extension used play mod music compile 3rd-party hack called stos 2.07 designed make stos run even tos versions behave atari falcon around 2001 françois lionet released via clickteam website source code stos basic 4th april 2019 françois lionet announced release amos2 website amos2.tech amos2 replaces stos amos together using javascript code interpreter making new development system independent generally deployed internet browsers possible extend functionality stos adding extensions added commands language increased functionality first extension released stos maestro added ability play sampled sounds stos maestro plus stos maestro bundled sound-sampler cartridge extensions included tome stos 3d ste extension misty missing link control extension extra ninja tracker extensions kept stos alive many years release giving programmers ability rapidly create game without knowing internals stos criticised slow especially intensively using non-high-level commands allowing user program structured manner 1990 amos basic released amiga originally meant shortly follow release stos atari st. amos released two years uk release stos turned blessing disguise amiga community thanks extra development time amos take advantage extra amiga hardware commands stos style basic completely different line-numbers many structured programming constructs one time stos club newsletter published program allowed reader program stos using style often possible directly convert stos basic programs heavily rely extensions amos basic reverse usually true pc version called pcos mentioned never materialised instead publishers mandarin software renamed europress software one developers jawx francois lionet later form clickteam yves lamoureux went release klik click series games-creation tools dissimilar stos use primarily mouse-driven interface without need traditional code klik play games factory multimedia fusion multimedia fusion 2 released series
Programming language topics
powerpc g4 powerpc g4 designation used apple computer eyetech describe fourth generation 32-bit powerpc microprocessors apple applied name various though closely related processor models freescale former part motorola motorola freescale proper name family processors powerpc 74xx macintosh computers powerbook g4 ibook g4 laptops power mac g4 power mac g4 cube desktops took name processor powerpc g4 processors also used emac first-generation xserves first-generation mac minis imac g4 introduction powerpc 970 apple completely phased g4 series desktop models selected 64-bit ibm-produced powerpc 970 processor basis powerpc g5 series last desktop model used g4 mac mini comes intel processor last portable use g4 ibook g4 replaced intel-based macbook powerbook g4 replaced intel-based macbook pro powerpc g4 processors also popular computer systems amigaone series computers pegasos genesi besides desktop computers powerpc g4 popular embedded environments like routers telecom switches imaging media processing avionics military applications one take advantage altivec smp capabilities powerpc 7400 code-named max debuted august 1999 first processor carry g4 moniker chip operates speeds ranging 350 500 mhz contains 10.5 million transistors manufactured using motorola 0.20 μm hipermos6 process die measures 83 mm² features copper interconnects motorola promised apple deliver parts speed 500 mhz yields proved low initially forced apple take back advertised 500 mhz models powermac g4 power mac series downgraded abruptly 400 450 500 mhz processor speeds 350 400 450 mhz problems chip ironed incident generated rift apple-motorola relationship reportedly caused apple ask ibm assistance get production yields motorola 7400 series line 500 mhz model reintroduced february 16 2000 much 7400 design done motorola close co-operation apple ibm ibm third member aim alliance designed chip together motorola somerset design center chose manufacture see need back vector processing unit ultimately g4 architecture design contained 128-bit vector processing unit labelled altivec motorola apple marketing referred velocity engine powerpc 970 g5 first ibm-manufactured cpu implement vmx/altivec ibm reused old 7400 design still design motorola somerset xenon cpu xbox 360 also features vmx added proprietary extensions made especially microsoft power6 introduced 2007 ibms first big iron cpu also implement vmx altivec unit 7400 microprocessor four-way single precision 32-bit floating point math 16-way 8-bit 8-way 16-bit four-way 32-bit integer math single cycle furthermore vector processing unit superscalar two vector operations time compared intel x86 microprocessors time feature offered substantial performance boost applications designed take advantage altivec unit examples adobe photoshop utilises altivec unit faster rendering effects transitions apple ilife suite takes advantage unit importing converting files fly additionally 7400 enhanced support symmetric multiprocessing smp thanks improved cache coherency protocol mersi 64-bit floating point unit fpu derived part 604 series 603 series 32-bit fpu took two clock cycles accomplish 64-bit floating point arithmetic powerpc g4 family supports two bus technologies older 60x bus shares powerpc 600 powerpc 7xx families advanced mpx bus devices utilize 60x bus made compatible either 6xx 7xx processors enabling wide variety offerings clear cheap upgrade path keeping compatibility issues minimum primarily two companies manufacturing system controllers 7xx 7xxx computers tundra tsi1xx controllers marvell discovery controllers powerpc 7410 nitro low-power version 7400 manufactured 180 nm instead 200 nm like 7400 10.5 million transistors debuted powerbook g4 9 january 2001 chip added ability use half cache high-speed non-cached memory mapped processor physical address space desired feature used embedded systems vendors mercury computer systems powerpc 7450 voyager v'ger major redesign g4 processor 33-million transistor chip extended significantly execution pipeline 7400 7 vs. 4 stages minimum reach higher clock speeds improved instruction throughput 3 branch vs. 2 branch per cycle compensate higher instruction latency replaced external l2 cache 2 mb 2-way set associative 64-bit data path integrated one 256 kb 8-way set associative 256-bit data path supported external l3 cache 2 mb 8-way set associative 64-bit data path featured many architectural advancements altivec unit improved 7450 instead executing one vector permute instruction one vector alu simple int complex int float instruction per cycle like 7400/7410 7450 motorola/freescale-followers execute two arbitrary vector instructions simultaneously permute simple int complex int float introduced 733 mhz power mac g4 9 january 2001 motorola followed interim release 7451 codenamed apollo 6 like 7455 early amigaone xe computers shipped 7451 processor enhancements 745x design gave nicknames g4e g4+ never official designations powerpc 7455 “ apollo 6 ” introduced january 2002 came wider 256-bit on-chip cache path fabricated motorola 0.18 µm 180 nm hipermos process copper interconnects soi first processor apple computer pass 1 ghz mark 7445 chip without l3 cache interface 7455 used amigaone xe g4 dual 1 ghz power mac g4 quicksilver 2002 powerpc 7447 apollo 7 slightly improved 7450/55 512 kb on-chip l2 cache manufactured 130 nm process soi hence drawing less power 58 million transistors 7447a introduced integrated thermal diode well dfs dynamic frequency scaling freescale able reach slightly higher clock 7457 additional l3 cache interface supporting 4 mb l3 cache 2 mb supported 7455 7450 however frequency scaling stagnated apple chose use 7447 instead 7457 despite 7457 l3 cache-enabled successor l3 cache-enabled 7455 apple used companies offer 7457 form upgrades power mac g4 imac g4 power mac g4 cube giga designs sonnet technology daystar technology use 7457 imac g4 upgrades powerlogix pegasos computer platform genesi also uses 7447 pegasos-ii/g4 7457 often used repair amigaone xe cpu module amigaos software 7457 installed may mistake amigaone pegasos ii computer never official 7457 boards released eyetech powerpc 7448 apollo 8 evolution powerpc 7447a announced first freescale technology forum june 2005 improvements higher clock rates 1.7 ghz officially easily 2.4 ghz overclocking larger 1 mb l2 cache faster 200 mhz front side bus lower power consumption 18 w 1.7 ghz fabricated 90 nm process copper interconnects soi powerpc 7448 users 2004 freescale renamed g4 core e600 changed focus general cpus high-end embedded soc devices introduced new naming scheme mpc86xx 7448 last pure g4 formed base new e600 core seven-stage three-issue pipeline powerful branch prediction unit handles sixteen instructions out-of-order enhanced altivec unit capable limited out-of-order execution 1 mb l2 cache list complete list known g4 based designs excluding newer core e600 designs pictures illustrations scale
Computer architecture
volume licensing software licensing volume licensing practice selling license authorizing one computer program used large number computers large number users customers licensing schemes typically business governmental educational institutions prices volume licensing varying depending type quantity applicable subscription-term example microsoft software available volume-licensing programs includes microsoft windows microsoft office traditionally volume licensing key vlk could supplied instances licensed computer program involved volume licensing popularity software service practices volume licensing customers supply software credentials belonging online user account instead used aspects services provisioning traditionally product key supplied computer programs acts analogously password computer programs old ask user prove entitlement response user provides key key however must used i.e one computer volume licensing key vlk however used several computers vendors take additional steps ensure products key used intended number efforts called product activation volume licenses always transferable example types microsoft volume license transferred provided formal transfer process completed enables microsoft register new owner small number software vendors specialize brokering transfers order allow selling volume licenses keys notable discount-licensing pioneered sale microsoft volume licenses way microsoft engaged volume licensing since inception enterprise sector primary market release windows xp 2001 microsoft introduced microsoft product activation digital rights management drm scheme curb software piracy among consumers verifying user entitlement product license time however volume-licensed versions windows xp exempt measure see starting windows vista microsoft introduced two volume licensing methods professionals charge installing windows organizations covered microsoft product activation first multiple activation keys mak windows xp volume licensing keys require product activation second key management server kms corresponding keys hosts activated via kms report back software license server every 180 days licenses using schemes procured via microsoft software assurance program large group microsoft customers oems assemble sell computers desktops laptops tablet computers mobile device devices sold oems windows license data stored computer bios area referred acpi_slic kms detect use previous microsoft products even storage device removed erased windows vista windows 7 slic data complementary volume licensing product key still supplied device user needs event reinstalling windows starting windows 8 however everything needed authorize device stored slic data 2010 microsoft introduced office 365 licensing program microsoft office microsoft exchange server skype business server products licensed based software service saas model exchange monthly subscription fee software updates support provisioning administration licensing additional services provided online web-based dashboard scheme licensed apps communicate recurrently microsoft internet product key needs issued user instead administrator needs sign microsoft account holds details licensed apps number payment methods account protected credentials username password introduced 2011 adobe creative cloud saas offering software produced adobe updates support provisioning administration licensing additional services provided internet exchange monthly subscription fee office 365 user account registered adobe required authorize software store payment information microsoft blocked several volume license keys abused service packs starting windows xp service pack 1 microsoft even developed new key verification engine windows xp service pack 2 could detect illicit keys even never used several security consultants condemned move microsoft saying leaving large install base unpatched various security holes irresponsible unpatched install base leveraged large scale internet attacks trojan horses used send spam e-mail others come microsoft defense arguing microsoft provide support illegal users much public outcry microsoft elected disable new key verification engine service pack 2 checks small list commonly used keys service pack 1 users existing installations windows xp also change product key following instructions microsoft volume license key commonly used bypass product activation early versions microsoft windows xp operating system codice_1 key part first warez release final version windows xp group called devils0wn 35 days official retail release 28 august 2001 key obsolete blacklisted microsoft since august 2004 affected computers display wga notification made famous partly featured popular image circulated internet retail launch windows xp image key written cd-r containing leaked operating system held front digital microsoft sign counting days release windows xp users using keys receive error message install latest service pack users told obtain legitimate license change product key client machine correct kms client setup keys authenticate kms server kms client keys well known documented publicly microsoft kms servers require minimum 25 clients properly activate also stop counting additional licenses beyond 50 automatically accept client key reaching 25 client threshold businesses operating kms servers required properly shield kms server behind firewalls reached internet used authorize illegal use kms client keys general public public exposure kms server result microsoft revoking server key thereby disabling attaching clients external kms server access desirable devices long-term leave away corporate network kms client activation expire six months able contact kms server situation business make accessible virtual private network vpn known devices outside corporate network unofficial kms server emulator exists activate windows office even software licensed paid regardless whether 25 computers network regardless whether previous version windows installed also program send kms requests legitimate kms server order fool server thinking 25 computers network microsoft considers exploits violation terms conditions
Operating systems
wikimedia foundation v. nsa suit filed united states district court district maryland nsa based fort meade maryland suit dismissed october 2015 judge t. s. ellis iii decision appealed four months later fourth circuit court appeals wikimedia foundation court appeals found dismissal valid plaintiffs except foundation whose allegations court found plausible enough legal standing case remanded lower court original plaintiffs besides wikimedia foundation national association criminal defense lawyers human rights watch amnesty international usa pen american center global fund women nation magazine ref name= nation 03/31/2015 /ref rutherford institute washington office latin america upstream surveillance first revealed may 2013 edward snowden former nsa analyst previous challenge aclu clapper v. amnesty international usa failed lack standing light leaks snowden included top secret nsa slide specifically referred wikipedia target http surveillance wikimedia foundation pushed forward legal complaint nsa violating users first fourth amendment rights since clapper government confirmed many key facts nsa upstream surveillance including conducts suspicionless searches. ref name= js 03/30/2015 /ref aclu attorney patrick toomey noted lawsuit particularly relevant plaintiffs engage hundreds billions international communications annually program upstream surveillance must necessarily sweep substantial part communications august 6 2015 defendants national security agency et al brought motion dismiss arguing plaintiffs plausibly shown injured upstream collection data thus lack standing sue response electronic frontier foundation filed amicus brief behalf group libraries booksellers sides presented oral arguments hearing september 25 2015 october 23 2015 district court district maryland dismissed suit grounds standing us district judge t. s. ellis iii ruled plaintiffs could plausibly prove subject upstream surveillance echoing 2013 decision clapper v. amnesty international us wikimedia foundation said expected appeal decision foundation said complaint merit question upstream surveillance captured communications user community wikimedia foundation electronic frontier foundation filed amicus brief support plaintiffs said perverse dismiss suit lack proof standing surveillance program complained secret urged federal courts tackle serious constitutional issues upstream surveillance presents plaintiffs filed appeal united states court appeals fourth circuit february 17 2016 may 23 2017 fourth circuit court appeals vacated dismissal lower court wikimedia complaints court appeals ruled foundation allegations nsa fourth amendment violations plausible enough survive facial challenge standing finding potential harm done nsa collection private data speculative court thereby remanded suit foundation ordered district court maryland continue proceedings court inversely affirmed dismissal ellis suits plaintiffs finding court noted non-wikimedia plaintiffs made strong enough case operations affected upstream scope
Computer security
european union vs. google since 2010 european union launched three separate antitrust investigations google violating eu competition laws due dominant position market cases resulted formal charges google related google shopping google adsense android operating system date google found guilty antitrust behavior cases related google shopping android fined 10 november 2010 european commission opened formal investigation google search algorithm following number complaints issued smaller web companies google downgrading placement results returned google search results google preferentially favoring products competitors ec investigation also considered issues google terms use google adsense prevented using adsense use advertising google competitors 15 april 2015 five years investigation ec issued first statement objections towards google related towards preferential treatment google shopping product including google product search search results specific complaints issued ec included 27 june 2017 google found guilty fined largest antitrust fine issued ec google denied european union accusations made statement claiming “ services helped region digital economy grow ” fine represented 2.5 google 2016 revenue competition google pushing company individually monitored fear losing business dominant search engine would include investigating overviewing google prized search page algorithm pagerank eu competition commission decided monitor decision google compliance due obligation report eucc regular basis every four months although issue seems like close european commission believes continue time order comply google effectively separating comparison shopping service company fine google shopping service still part google run completely separately revenues profits move allow google avoid fines according bloomberg complies european union order allowing even treatment businesses matter compete google however even though google complying part company still appealing decision google responded appeal papers eu antitrust fine stating eu chair misstated facts show enough evidence prove site hurt rivals google wants fine either overturned reduced appeal based six arguments two court prove google favored shopping service placing paid ads top search results two stated courts misstated facts evidence two argued fine warranted possible penalty investigating case related google shopping ec found additional evidence related potential antitrust issues related google adsense issued statement complaints 14 july 2016 complaints centered google licensed adsense direct partners 20 march 2019 european commission imposed fine 1.49 € billion google abusive practices online advertising ec actions investigate google approach android operating system predicated two complaints received first complaint came fairsearch fairsearch established 2010 coalition travel-related web companies including expedia tripadvisor try fight google proposed acquisition ita developed airfare search software group shifted towards becoming google watchdog group looking instances google activities considered potentially anti-competition companies like microsoft nokia oracle joined group support broader effort prior attention android system fairsearch issued complaints ec google search engines would preferentially weight results google services partners others part antitrust investigations conducted eu since 2010 april 2013 european branch fairsearch filed formal complaint eu still investigating google previous complaints citing google practices android violated various eu antitrust laws complaint identified google required original equipment manufacturer oem wanting install google suite android apps including access google play store license entire suite feature predominately mobile device second anti-trust complaint google filed aptoide june 2014 alternative marketplace android apps aptoide asserted google approach google made difficult alternatives google play store installed components part google android open source project moved google mobile services suite including gmail google maps play store 15 april 2015 european commission started official investigation google following complaints filed fairsearch apotoide internal evaluation complaints year ec stated company may taken unlawful actions maintain google dominant position mobile market licensed suite android applications new investigation announced alongside ec findings antitrust investigation google search engine practices otherwise treated separate action google commission identified three points concern first statement objections google countered investigation practices android different apple inc. microsoft bundles proprietary apps respective ios windows phone oems still able distribute android-based phones without google suite apps investigation google formed alphabet inc. holding company google various subsidiaries google becoming one alphabet subsidiaries year 20 april 2016 european commission announced issue second statement objections addressing google alphabet within charges new set complaints amending first statement objections asserted google violated eu antitrust laws potential fines case google found violating antitrust laws maximum amount 10 company annual revenue time issuing second statement objection 19 july 2018 eu fined google google responded would appeal fine october 2018 according company spokesperson al verney android created choice everyone less date fine biggest ever imposed european union company anti-competitive behaviour european union competition commissioner margrethe vestager part decision google stated eu found google search anti-trust case 2017 google attempt settle issues android anti-trust issues far late eu filed initial charges google october 2018 google revamped would distribute google play store android future charging licensing fee store without requiring installation google apps making free pre-install google apps want furthermore google hardware partners allowed market devices eu run rival versions android operating systems march 2019 google announced give european users android phones option browser search engine want phone time purchase comply eu decision
Operating systems
subgraph operating system subgraph os linux distribution designed resistant surveillance interference sophisticated adversaries internet based upon debian linux operating system mentioned edward snowden showing future potential subgraph os designed locked features aim reduce attack surface operating system increase difficulty required carry certain classes attack accomplished system hardening proactive ongoing focus security attack resistance subgraph os also places emphasis ensuring integrity installed software packages deterministic compilation subgraph os notable features include security subgraph os uses sandbox containers questioned comparison qubes uses virtualization another security focused operating system attacker trick subgraph user run malicious unsandboxed script via os default nautilus file manager terminal also possible run malicious code containing .desktop files used launch applications malware also bypass subgraph os application firewall also design subgraph isolate network stack like qubes os prevent bad usb exploits
Operating systems
joy law computing computing joy law first formulated sun microsystems co-founder bill joy 1983 states peak computer speed doubles year thus given simple function time specifically peak computer speed attained year expressed mips another statement attributed bill joy also referred joy law holds smartest people work someone else
Computer architecture
jdk enhancement proposal jdk enhancement proposal jep process drafted oracle corporation collecting proposals enhancements java development kit openjdk words oracle jep serve long-term roadmap jdk release projects related efforts jep process intended replace java community process still required approve changes java api language rather allow openjdk committers work informally becoming formal java specification request
Programming language topics
iphone 8 iphone 8 iphone 8 plus smartphones designed developed marketed apple inc eleventh generation iphone announced september 12 2017 alongside higher-end iphone x steve jobs theater apple park campus released september 22 2017 succeeding iphone 7 iphone 7 plus besides addition glass back designs iphone 8 8 plus largely similar predecessors notable changes include addition inductive charging faster processor improved cameras displays iphone 8 8 plus share internal hardware iphone x reception phones mixed reviewers praising addition inductive charging new apple a11 processor significantly criticizing aging design august 31 2017 apple sent press invites media event steve jobs theater apple park campus september 12 2017 iphone 8 iphone 8 plus announced event released september 22 2017 april 9 2018 apple introduced iphone 8 red color finish black front support partnership product red aids fundraising campaign iphone 8 8 plus retain retina hd display found iphone 7 feature true tone technology allowing automatic screen adjustments based surrounding ambient lighting play hdr10 dolby vision content despite hdr-ready display done down-converting hdr content fit display still enhancements dynamic range contrast wide color gamut compared standard content iphone 8 features 12 mp camera autofocus f/1.8 aperture optical image stabilization capable capturing 4k video 24 30 60 frames per second 1080p video 30 60 120 240 frames per second iphone 8 plus upgrades main camera wide-angle lens 10× digital zoom 2× optical zoom retains second telephoto lens similar one found iphone 7 plus improved depth-of-field lighting effects portrait mode models 7 mp front camera f/2.2 aperture capable capturing 1080p video 30 frames per second 720p video 240 frames per second along face detection high-dynamic range iphone 8 8 plus contain apple a11 bionic system-on-chip hexa-core processor company says features two cores 25 faster iphone 7 a10 processor four cores 70 faster prior model phones also feature apple-designed graphics processing unit 30 faster prior units level performance a10 half power phones glass backs instead complete aluminum housing found prior models enabling use qi inductive charging phones rated ip67 water resistance models come 64 256 gigabyte storage options offered silver gold space gray color options product red special edition version red black front released april 9 2018 iphone 7 7 plus special editions white front iphone 8 6 10 repairability score ifixit mainly due use excessive glue battery glass back iphone 8 8 plus shipped ios 11 launch support ios 12 also support ios 13 samuel axon ars technica called a11 processor marvelous feat engineering writing offers industry-leading performance axon also praised cameras writing colors great low light performance good smartphone chris velazco engadget praised speed a11 processor build quality excellent camera criticizing design familiarities previous iphone generations limited water-protection levels compared competitors john mccann techradar enjoyed feel glass back despite criticizing phone overall design mccann also praised camera called inductive charging useful addition iphone lineup david pierce wired similarly stated iphone 8 models overshadowed iphone x despite calling virtually perfect phones pierce praised performance cameras displays repeatedly criticizing outdated design nilay patel verge called iphone 8 default option noting 8 models stand almost universally overlooked apple new iphone launched iphone x nevertheless praised device form factor easy non-slippery hold display addition true tone technology upgraded speakers though cited issues inductive charging speed wireless pads well price iphone 8 plus 256 gb close iphone x. patel also criticized iphone 8 aging design dating back iphone 6 released 2014 notable critique thick bezels compared 2017 smartphones designed nearly bezel-less faces incorporate larger screens similar form factor iphone 8 8 plus also criticized durability drop tests performed showed rear glass durable glass ever smartphone claimed apple camera testing company dxomark gave camera iphone 8 rating 92 8 plus rating 94 giving title best smartphone cameras tested company samsung galaxy note 8 later matched iphone 8 plus identical overall score 94 later overtaken google pixel 2 scored 98 rating august 31 2018 apple announced small percentage iphone 8 devices released september 2017 march 2018 contained manufacturing defect logic board fault affected iphone 8 models sold australia china hong kong india japan macau new zealand united states defective devices may experience unexpected reboots frozen unresponsive screen may fail turn users affected device determined serial number device replaced free apple issue affect iphone 8 plus
Operating systems
rock ridge rock ridge interchange protocol rrip ieee p1282 extension iso 9660 volume format commonly used cd-rom dvd media adds posix file system semantics availability extension properties allows better integration unix unix-like operating systems standard takes name fictional town rock ridge mel brooks film blazing saddles rrip extensions briefly rrip extensions built upon related standard system use sharing protocol susp ieee p1281 susp provides generic way including additional properties directory entry reachable primary volume descriptor pvd iso 9660 volume every directory entry optional system use area whose contents undefined left interpreted system susp defines method subdivide area multiple system use fields identified two-character signature tag idea behind susp would enable number independent extensions iso 9660 rrip created included volume without conflicting also allows inclusion property data would otherwise large fit within limits system use area susp defines several common tags system use fields rrip defines additional susp tags support posix semantics along format meaning corresponding system use fields known susp fields include linux kernel built config_zisofs transparently decompresses data files marked additionally libburnia project proposed aaip would add following susp tag note apple iso 9660 extensions technically follow susp standard however basic structure aa ab fields defined apple forward compatible susp care volume use apple extensions well rrip extensions amiga rock ridge similar rrip except provides additional properties used amiga operating system built susp standard defining -tagged system use field thus amiga rock ridge posix rrip may used simultaneously volume specific properties supported extension additional amiga-bits files support attribute p stands pure bit indicating re-entrant command attribute script bit indicating batch file includes protection flags plus optional comment field extensions introduced angela schmidt help andrew young primary author rock ridge interchange protocol system use sharing protocol first publicly available software master cd-rom amiga extensions makecd amiga software angela schmidt developed together patrick ohly masteriso also recognizes extension also supported frying pan support latter one program uncredited amiga cd-rom filesystems supporting extensions amicdfs asimcdfs cachecdfs babelcdromfs users want access comments protection bits amiga files present cds could simply mount new logical units associated physical unit using one cd-rom filesystems mentioned
Computer file systems
world spider catalog world spider catalog wsc online searchable database concerned spider taxonomy aims list accepted families genera species well provide access related taxonomic literature wsc began series individual web pages 2000 created norman i. platnick american museum natural history platnick retirement 2014 natural history museum bern switzerland took catalog converting relational database 48,265 accepted species listed order araneae spiders seventh-largest number species orders existence world spider catalog makes spiders largest taxon online listing updated regularly described exhaustive resource promoted rigorous scholarship amplified productivity taxonomy spiders
Databases
usplash usplash software project ubuntu community historically scrolling text verbose mode typically appeared linux computers boot usplash replaces scrolling-text screens graphical splash screen designed replace bootsplash thing kernel space level since usplash operates user space updated without recompiling kernel usplash uses linux framebuffer interface alternatively direct vesa access display splash screen ubuntu 9.10 karmic koala usplash used preliminary stages booting xsplash takes ubuntu 10.04 lts lucid lynx usplash fully replaced plymouth uses direct rendering manager drm kms driver
Operating systems
apmonitor advanced process monitor apmonitor modeling language differential algebraic dae equations free web-service local server solving representations physical systems form implicit dae models apmonitor suited large-scale problems solves linear programming integer programming nonlinear programming nonlinear mixed integer programming dynamic simulation moving horizon estimation nonlinear model predictive control apmonitor solve problems directly calls nonlinear programming solvers apopt bpopt ipopt minos snopt apmonitor api provides exact first second derivatives continuous functions solvers automatic differentiation sparse matrix form julia matlab python mathematical programming languages apmonitor integration web-service apis gekko optimization suite recent extension apmonitor complete python integration interfaces built-in optimization toolboxes modules load process solutions optimization problems apmonitor object-oriented modeling language optimization suite relies programming languages load run retrieve solutions apmonitor models data compiled run-time translated objects solved optimization engine apopt ipopt optimization engine specified apmonitor allowing several different optimization engines switched simulation optimization mode also configurable reconfigure model dynamic simulation nonlinear model predictive control moving horizon estimation general problems mathematical optimization first step solving problem mathematical model expressed terms variables equations hock schittkowski benchmark problem 71 used test performance nonlinear programming solvers particular optimization problem objective function formula_1 subject inequality constraint formula_2 equality constraint formula_3 four variables must lower bound 1 upper bound 5 initial guess values formula_4 mathematical model translated apmonitor modeling language following text file problem solved python first installing apmonitor package pip install apmonitor following python code installing python required module apmonitor package installed imported apm_solve function solves optimization problem solution returned programming language processing analysis similar interfaces available matlab julia minor differences syntax extending capability modeling language important significant pre- post-processing data solutions often required solving complex optimization dynamic simulation estimation control problems highest order derivative necessary return dae ode form called differentiation index standard way dealing high-index daes differentiate equations put index-1 dae ode form see pantelides algorithm however approach cause number undesirable numerical issues instability syntax similar modeling languages gproms apmonitor solves daes index without rearrangement differentiation example index-3 dae shown pendulum motion equations lower index rearrangements return system equations ode form see index 0 3 pendulum example many physical systems naturally expressed differential algebraic equation include models direct current dc motor blood glucose response insulin dependent patient listed representative differential algebraic equations encountered many branches science engineering
Programming language topics
hierarchical file system hierarchical file system hfs proprietary file system developed apple inc. use computer systems running mac os originally designed use floppy hard disks also found read-only media cd-roms hfs also referred mac os standard hfs standard successor hfs plus also called mac os extended hfs extended introduction mac os x 10.6 apple dropped support formatting writing hfs disks images remain supported read-only volumes starting macos 10.15 hfs disks longer read apple introduced hfs september 1985 specifically support apple first hard disk drive macintosh replacing macintosh file system mfs original file system introduced year half earlier first macintosh computer hfs drew heavily upon apple first hierarchical operating system sos failed apple iii also served basis hierarchical file systems apple iie apple lisa hfs developed patrick dirks bill bruffey shared number design features mfs available file systems time dos fat files could multiple forks normally data resource fork allowed main data file stored separately resources icons might need localized files referenced unique file ids rather file names file names could 255 characters long although finder supported maximum 31 characters however mfs optimized used small slow media namely floppy disks hfs introduced overcome performance problems arrived introduction larger media notably hard drives main concern time needed display contents folder mfs file directory listing information stored single file system search build list files stored particular folder worked well system hundred kilobytes storage perhaps hundred files systems grew megabytes thousands files performance degraded rapidly solution replace mfs directory structure one suitable larger file systems hfs replaced flat table structure catalog file uses b-tree structure could searched quickly regardless size hfs also redesigned various structures able hold larger numbers 16-bit integers replaced 32-bit almost universally oddly one places upsizing take place file directory limits hfs total 65,535 files logical disk hfs proprietary file system format well-documented usually solutions available access hfs-formatted disks modern operating systems apple introduced hfs necessity first 20 mb hard disk offering macintosh september 1985 loaded ram mfs floppy disk boot using patch file hard disk 20 however hfs widely introduced included 128k rom debuted macintosh plus january 1986 along larger 800 kb floppy disk drive macintosh also used hfs introduction hfs first advancement apple leave macintosh computer model behind original 128k macintosh lacked sufficient memory load hfs code promptly discontinued 1998 apple introduced hfs plus address inefficient allocation disk space hfs add improvements hfs still supported current versions mac os starting mac os x hfs volume used booting beginning mac os x 10.6 snow leopard hfs volumes read-only created updated macos sierra 10.12 apple release notes state hfs standard filesystem longer supported however read-only hfs standard support still present sierra works previous versions storage volume inherently divided logical blocks 512 bytes hierarchical file system groups logical blocks allocation blocks contain one logical blocks depending total size volume hfs uses 16-bit value address allocation blocks limiting number allocation blocks 65,535 2-1 five structures make hfs volume catalog file stores file directory records single data structure results performance problems system allows multitasking one program write structure time meaning many programs may waiting queue due one program hogging system also serious reliability concern damage file destroy entire file system contrasts file systems store file directory records separate structures dos fat file system unix file system structure distributed across disk means damaging single directory generally non-fatal data may possibly re-constructed data held non-damaged portions additionally limit 65,535 allocation blocks resulted files minimum size equivalent 1/65,535th size disk thus given volume matter size could store maximum 65,535 files moreover file would allocated space actually needed allocation block size disks small little consequence individual allocation block size trivial disks started approach 1 gb mark smallest amount space file could occupy single allocation block became excessively large wasting significant amounts disk space example 1 gb disk allocation block size hfs 16 kb even 1 byte file would take 16 kb disk space situation less problem users large files pictures databases audio larger files wasted less space percentage file size users many small files hand could lose copious amount space due large allocation block size made partitioning disks smaller logical volumes appealing mac users small documents stored smaller volume would take much less space resided large partition problem existed fat16 file system hfs saves case file created renamed case-insensitive operation
Computer file systems
ram drive ram drive also called ram disk block random-access memory primary storage volatile memory computer software treating memory disk drive secondary storage sometimes referred virtual ram drive software ram drive distinguish hardware ram drive uses separate hardware containing ram type battery-backed solid-state drive performance ram drive general orders magnitude faster forms storage media ssd hard drive tape drive optical drive performance gain due multiple factors including access time maximum throughput type file system file access time greatly reduced since ram drive solid state mechanical parts physical hard drive optical media cd-rom dvd blu-ray must move head optical eye position tape drives must wind rewind particular position media reading writing occur ram drives access data memory address given file movement alignment positioning necessary second maximum throughput ram drive limited speed ram data bus cpu computer forms storage media limited speed storage bus ide pata sata usb firewire compounding limitation speed actual mechanics drive motors heads eyes third file system use ntfs hfs ufs ext2 etc. uses extra accesses reads writes drive although small add quickly especially event many small files vs. larger files temporary internet folders web caches etc. storage ram volatile memory means lost event power loss whether intentional computer reboot shutdown accidental power failure system crash general weakness data must periodically backed persistent-storage medium avoid loss sometimes desirable example working decrypted copy encrypted file many cases data stored ram drive created data permanently stored elsewhere faster access re-created ram drive system reboots apart risk data loss major limitation ram drives limited capacity constrained amount ram within machine multi-terabyte-capacity persistent storage become commoditized 2012 whereas ram still measured gigabytes ram drives use normal ram main memory partition hard drive rather actually accessing data bus normally used secondary storage though ram drives often supported directly operating system via special mechanisms operating system kernel possible also create manage ram drive application usually battery backup needed due temporary nature information stored ram drive uninterrupted power supply keep entire system running power outage necessary ram drives use compressed file system cramfs allow compressed data accessed fly without decompressing first convenient ram drives often small due higher price per byte conventional hard drive storage first software ram drive microcomputers invented written jerry karlin uk 1979/80 software known silicon disk system developed commercial product marketed jk systems research became microcosm research ltd company joined peter cheesewright microcosm ltd idea enable early microcomputers use ram cpu could directly address making bank-switched ram behave like disk drive much faster disk drives especially days hard drives readily available machines silicon disk launched 1980 initially cp/m operating system later ms-dos due limitations memory addressing apple ii series commodore computers ram drive also popular application commodore 64 commodore 128 systems ram expansion units apple ii series computers 64kb ram apple computer supported software ram drive natively prodos systems 128kb ram prodos would automatically allocate ram drive named /ram ibm added ram drive named vdisk.sys pc dos version 3.0 august 1984 first dos component use extended memory vdisk.sys available microsoft ms-dos unlike components early versions pc dos written ibm microsoft included similar program ramdrive.sys ms-dos 3.2 released 1986 could also use expanded memory discontinued windows 7 dr-dos dr family multi-user operating systems also came ram disk named vdisk.sys multiuser dos ram disk defaults drive letter memory drive amigaos built ram drive since release version 1.1 1985 still amigaos 4.1 2010 apple computer added functionality apple macintosh system 7 memory control panel 1991 kept feature life mac os 9 mac os x users use hdid newfs newfs hfs mount utilities create format mount ram drive ram drive innovation introduced 1986 made generally available 1987 perry kivolowitz amigaos ability ram drive survive crashes reboots called asdg recoverable ram disk device survived reboots allocating memory dynamically reverse order default memory allocation feature supported underlying os reduce memory fragmentation super-block written unique signature could located memory upon reboot super-block rrd disk blocks maintained check sums enable invalidation disk corruption detected first asdg rrd locked asdg memory boards used selling feature later asdg rrd made available shareware carrying suggested donation 10 dollars shareware version appeared fred fish disks 58 241 amigaos would gain recoverable ram disk called rad version 1.3 many unix unix-like systems provide form ram drive functionality /dev/ram linux md 4 freebsd ram drives particularly useful high-performance low-resource applications unix-like operating systems sometimes configured also specialized ultra-lightweight linux distributions designed boot removable media stored ramdisk entire session ram drives use dram memory exclusively dedicated function extremely low latency storage device memory isolated processor directly accessible manner normal system memory 2002 cenatek produced rocket drive max 4gb four dimm slots pc133 memory maximum 4 gigabytes storage time common desktop computers used 64 128 megabytes pc100 pc133 memory 1 gigabyte pc133 modules largest available time cost approximately 1300 fully outfitted rocket drive 4 gb storage would cost 5600 2005 gigabyte technology produced i-ram max 4gb functioned essentially identical rocket drive except upgraded use newer ddr memory technology though also limited maximum 4gb capacity devices dynamic ram requires continuous power retain data power lost data fades away rocket drive connector external power supply separate computer option external battery retain data power failure i-ram included small battery directly expansion board 10-16 hours protection devices used sata 1.0 interface transfer data dedicated ram drive system sata interface slow bottleneck limited maximum performance ram drives drives still provided exceptionally low data access latency high sustained transfer speeds compared mechanical hard drives 2006 gigabyte technology produced gc-ramdisk max 8gb 2nd generation creation i-ram maximum 8gb capacity twice i-ram used sata-ii port twice i-ram one best selling points could boot ram drive use needed 2007 acard technology produced ans-9010 serial ata ram disk max 64gb quote tech report ans-9010 eight ddr2 dimm slots support 8gb memory per slot ans-9010 also features pair serial ata ports allowing function single drive masquerade pair drives easily split even faster raid 0 array 2009 acard technology produced acard ans-9010ba 5.25 dynamic ssd sata-ii ram disk max 64gb uses single sata-ii port 2014 ddrdrive llc produced ddrdrive x1 claims fastest solid state drive world drive primary 4gb ddr dedicated ram drive regular use backup recall 4gb slc nand drive intended market keeping recording log files power loss data saved internal 4gb ssd 60 seconds via use battery backup thereafter data recovered back ram power restored host power loss triggers ddrdrive x1 backup volatile data on-board non-volatile storage pros cons
Computer file systems
functional reactive programming functional reactive programming frp programming paradigm reactive programming asynchronous dataflow programming using building blocks functional programming e.g map reduce filter frp used programming graphical user interfaces guis robotics games music aiming simplify problems explicitly modeling time original formulation functional reactive programming found icfp 97 paper functional reactive animation conal elliott paul hudak frp taken many forms since introduction 1997 one axis diversity discrete vs. continuous semantics another axis frp systems changed dynamically earliest formulation frp used continuous semantics aiming abstract many operational details important meaning program key properties formulation semantic model frp side-effect free languages typically terms continuous functions typically time formulations event-driven frp elm version 0.17 require updates discrete event-driven formulations pushed practical frp focusing semantics simple api implemented efficiently setting robotics web-browser formulations common ideas behaviors events combined signals always current value change discretely pointed ordinary frp model inputs outputs poorly suited interactive programs lacking ability run programs within mapping inputs outputs may mean one following solutions used two types frp systems push-based pull-based push-based systems take events push signal network achieve result pull-based systems wait result demanded work backwards network retrieve value demanded frp systems yampa use sampling samples pulled signal network approach drawback network wait duration one computation step find changes input sampling example pull-based frp reactive etage libraries hackage introduced approach called push-pull frp combines best push-based pull-based frp approach next event purely defined stream list fixed events times demanded event constructed purely defined streams act like lazy lists haskell pull-based half push-based half used events external system brought external events pushed consumers find event instant issued functional reactive programming used create mobile applications android ios
Programming language topics
airtable airtable cloud collaboration service headquartered san francisco founded 2012 howie liu andrew ofstad emmett nicholas airtable spreadsheet-database hybrid features database applied spreadsheet fields airtable table similar cells spreadsheet types 'checkbox 'phone number 'drop-down list reference file attachments like images users create database set column types add records link tables one another collaborate sort records publish views external websites airtable six basic components avoid need form single large table related data multiple tables airtables provides option link records different tables airtable allows linking existing tables related records creating new linked table also multiple links existing tables airtable allows multiple users work simultaneously base allowing productivity workplace new collaborator added clicking share button found top base providing email id collaborator owner set permission level collaborator sharing base three permission levels airtable base namely creator edit read multiple bases required team formed airtable airtable team hold multiple bases collaborators team work available bases team four permission levels team unlike base three extra permission level team owner full access team base bases easily shared public one need airtable account view published bases view bases shared public called airtable views views embedded one website allows website users see real time information base without needing airtable account one possible use-case airtable form used take survey product feedback received customer also shown public sharing airtable view airtable introduced forms july 2015 forms could used collect data others like co-workers customers public form easily created existing base data collected form automatically organized airtable base airtable allows user organize required fields form separate link created every airtable form link shared others get required data airtable form also embedded website get feedback website users airtable api used connect web services information exchanged external web applications airtable using zapier platform airtable connect 450 applications websites changes set triggers actions connected applications airtable provides greater sophistication backup data allow users undo/redo airtable periodically snapshots base previous version base needed appropriate snapshot selected user snapshots list addition user manually snapshot base time airtable introduced version 2.0 ios application december 2015 allowing users work tables iphone airtable android also available airtable provides api provide ability users build application solutions fitting exact problems key present overview section necessary use airtable api key kept secret api follows rest semantics uses json encode objects uses standard http codes signal operation outcomes initially user create base airtable airtable api used create read update delete records i.e crud 2016 airtable api allow users create modify base schema airtable uses 256 bit advanced encryption standard aes protect data also uses 256-bit ssl/tls encryption data transit
Distributed computing architecture
wordweb wordweb international english dictionary thesaurus program microsoft windows ios android mac os x available download online program partly based wordnet database program activated holding ctrl right-clicking word almost program opens wordweb main window definitions help program usually resides tray thesaurus integrated dictionary synonyms well detailed categorization relationship words shown definition program shows users also actively improve dictionary thesaurus submitting errors missing words/phrases/senses enhancement requests program two versions free version word list search anagram customization features paid version called 'wordweb pro wordweb 5 added ability list entries three web sources wikipedia wiktionary wordweb online details presented three separate tabs built client application version 6 added audio pronunciations support third-party oxford chambers add-on dictionaries wordweb 7 mainly content upgrade revised definition sound database also significantly updated one-click support latest browsers 64-bit programs changes version include 1 new revised definitions related words 2 updated audio pronunciations 3 improved one-click integration programs 4 better one-click 64-bit windows 8 program support 5 keyboard hotkeys bookmark menu items 6 auto-detect support latest 3-rd party concise oxford merriam-webster wordweb 7 requires windows windows xp windows vista windows 7 windows 8 windows 10 desktop wordweb 8 includes one-click keyboard lookup including thunderbird firefox without plugin support windows xp dropped version wordweb including pro available unix however used wine similar program includes wordweb pro features artha available linux windows port macintosh promised artha based wordnet database use free version subject license terms however might used educational institution free cost students even violate said terms wordweb regionalized specific dictionaries australian british canadian american irish new zealand south african indian english
Web technology
pentoo pentoo live cd live usb designed penetration testing security assessment based gentoo linux pentoo provided 32 64 bit installable live cd pentoo also available overlay existing gentoo installation features packet injection patched wifi drivers gpgpu cracking software lots tools penetration testing security assessment pentoo kernel includes grsecurity pax hardening extra patches binaries compiled hardened toolchain latest nightly versions tools available tools installed versioned ebuilds open-ended ebuilds making possible pull latest subversions still installs tracked package management following tool categories included pentoo uses rolling releases periodic iso snapshots latest committed updates
Computer security
altivec altivec single-precision floating point integer simd instruction set designed owned apple ibm freescale semiconductor formerly motorola semiconductor products sector — aim alliance implemented versions powerpc processor architecture including motorola g4 ibm g5 power6 processors p.a semi pwrficient pa6t altivec trademark owned solely freescale system also referred velocity engine apple vmx vector multimedia extension ibm p.a semi altivec refers instruction set implementations cpus produced ibm motorola separate terms logic design date ibm core included altivec logic design licensed motorola vice versa altivec standard part power isa v.2.03 specification never formally part powerpc architecture specification although used powerpc instruction formats syntax occupied opcode space expressly allocated purposes vmx/altivec sse feature 128-bit vector registers represent sixteen 8-bit signed unsigned chars eight 16-bit signed unsigned shorts four 32-bit ints four 32-bit floating point variables provide cache-control instructions intended minimize cache pollution working streams data also exhibit important differences unlike sse2 vmx/altivec supports special rgb pixel data type operate 64-bit double precision floats way move data directly scalar vector registers keeping load/store model powerpc risc design vector registers like scalar registers loaded stored memory however vmx/altivec provides much complete set horizontal operations work across elements vector allowable combinations data type operations much complete thirty-two 128-bit vector registers provided compared eight sse sse2 extended 16 x86-64 vmx/altivec instructions take three register operands compared two register/register register/memory operands ia-32 vmx/altivec also unique support flexible vector permute instruction byte resulting vector value taken byte either two vectors parametrized yet another vector allows sophisticated manipulations single instruction recent versions gnu compiler collection gcc ibm visualage compiler compilers provide intrinsics access vmx/altivec instructions directly c c++ programs version 4 gcc also includes auto-vectorization capabilities attempt intelligently create vmx/altivec accelerated binaries without need programmer use intrinsics directly vector type keyword introduced permit declaration native vector types e.g. codice_1 declares 128-bit vector variable named foo containing sixteen 8-bit unsigned chars full complement arithmetic binary operators defined vector types normal c expression language used manipulate vector variables also overloaded intrinsic functions codice_2 emit appropriate op code based type elements within vector strong type checking enforced contrast intel-defined data types ia-32 simd registers declare size vector register 128 64 bits case 128-bit register whether contains integers floating point values programmer must select appropriate intrinsic data types use e.g. codice_3 adding two vectors containing eight 16-bit integers power vector media extension vmx developed 1996 1998 collaborative project apple ibm motorola apple primary customer power vector media extension vmx apple switched intel-made x86-based cpus june 6 2005 used accelerate multimedia applications quicktime itunes key parts apple mac os x including quartz graphics compositor companies adobe used altivec optimize image-processing programs adobe photoshop motorola first supply altivec enabled processors starting g4 line altivec also used embedded systems high-performance digital signal processing ibm consistently left vmx earlier power microprocessors intended server applications useful power6 microprocessor introduced 2007 implements altivec last desktop microprocessor ibm powerpc 970 dubbed g5 apple also implemented altivec hardware similar powerpc 7400 altivec brandname trademarked freescale previously motorola standard category vector part power isa v.2.03 specification category also known vmx used ibm velocity engine brand name previously used apple cell broadband engine used amongst things playstation 3 also supports power vector media extension vmx ppu spu isa enhanced architecturally similar freescale bringing enhanced version altivec e6500 based qoriq processors ibm enhanced vmx use xenon xbox 360 called enhancement vmx128 enhancements comprise new routines targeted gaming accelerating 3d graphics game physics total 128 registers vmx128 entirely compatible vmx/altivec number integer operations removed make space larger register file additional application-specific operations power isa v2.06 introduces new vsx vector-scalar instructions extend simd processing power isa support 64 registers support regular floating point decimal floating point vector execution power7 first power isa processor implement power isa v2.06 new instructions introduced ibm vector media extension category integer operations part vsx extension power isa 2.07 new integer vector instructions introduced ibm following vmx encodings part vsx extension power isa v3.0 shall introduced power9 processors c++ standard way accessing altivec support mutually exclusive use standard template library codice_4 class template due treatment vector reserved word compiler implement context sensitive keyword version vector however may possible combine using compiler-specific workarounds instance gcc one may codice_5 remove codice_6 keyword use gcc-specific codice_7 keyword place following processors altivec vmx vmx128 included
Computer architecture
omnipeek omnipeek packet analyzer software tool savvius liveaction company network troubleshooting protocol analysis supports application programming interface api plugins savvius formerly wildpackets founded 1990 ag group mahboud zabetian tim mccreery soon changed name wildpackets first product savvius written mac called etherpeek protocol analyzer ethernet networks later ported microsoft windows released 1997 2001 airopeek released added support wireless ieee 802.11 marketed wi-fi brand networks 2003 omniengine distributed capture engine released software hardware network recorder appliance morning july 15 2002 savvius building walnut creek california burnt ground however company survived fire mid-april 2015 company changed name wildpackets savvius broadened focus include network security june 2018 savvius acquired liveaction company provides network performance management visualization analytics software savvius acquired net3 group november 2000 product netsense expert system network troubleshooting converted plug-in integrated new version product called etherpeeknx savvius acquired optimized engineering corporation 2001 optimized network analysis training courses instructors added savvius services omnipeek apis front-end automation back-end analysis well mechanisms extend enhance program 40 plug-ins available omnipeek platform plug-ins range logging extensions full-blown applications hosted omnipeek remote adapters provide means capture packets stats remote adapters capture rmon netflow sflow cisco ap aruba ap linux boxes adapters available aggregate packets multiple network segments wireless channels time notable decoders protospecs decoder files interpreted text files extended user enhance display analysis existing protocols add knowledge completely new protocols without releasing new versions application plugin wizards omnipeek console omniengine microsoft visual studio project templates generate working plug-ins wizard run dialog appears providing options types functionality sample code generated wizard complete user left working plugin entry points adding application logic plug-in wizards enable development extensions omnipeek mypeek community portal website dedicated extension omnipeek provides plug-ins scripts adapters tools various levels support plug-ins posted expertise interested extending omnipeek placemap freely available standalone google maps packet sniffer application windows captures network traffic maps nodes google map placemap notable example extensibility uses exactly google map plugin also available omnipeek uses peek driver api capture packets
Computer security
middleware middleware computer software provides services software applications beyond available operating system described software glue middleware makes easier software developers implement communication input/output focus specific purpose application gained popularity 1980s solution problem link newer applications older legacy systems although term use since 1968 term commonly used software enables communication management data distributed applications ietf workshop 2000 defined middleware services found transport i.e tcp/ip layer set services application environment i.e application-level apis specific sense middleware described dash client-server -to- peer-to-peer middleware includes web servers application servers content management systems similar tools support application development delivery objectweb defines middleware software layer lies operating system applications side distributed computing system network services regarded middleware include enterprise application integration data integration message oriented middleware mom object request brokers orbs enterprise service bus esb database access services often characterised middleware language specific implementations support heterogeneous features related communication features examples database-oriented middleware include odbc jdbc transaction processing monitors distributed computing system middleware loosely divided two categories—those provide human-time services web request servicing perform machine-time latter middleware somewhat standardized service availability forum commonly used complex embedded systems within telecom defense aerospace industries term middleware used contexts well middleware sometimes used similar sense software driver abstraction layer hides detail hardware devices software application
Distributed computing architecture
vdiworks vdiworks american software company founded 2008 provides services like desktop virtualization desktop service daas networking pcoip cloud computing vdiworks built first pcoip broker connection industry ’ pcoip broker quad broking support vdiworks vdi technology service comes full physical management vdiworks helps virtual desktops new high-speed connection protocol vdiworks inc. started services 2008 like virtual desktop enablement management software offers fast remote desktop bring power windows ipad run microsoft office well access spreadsheets power point presentations pc documents travelling videooverip remoting protocol virtual desktops deliver multimedia performance multi-monitor capabilities allowing capitalize management improvements security enhancements lowered-tco result virtualization company provides virtual desktop platform vdp virtual desktop infrastructure management system combines connection brokering vm management health alerting inventory physical management support various remoting protocols vdivision system center operations manager 2007 combine power vdiworks virtual desktop platform ubiquity datacenter management capabilities system center addition vdiworks inc. introduced vdiworks2go extension vdiworks vdp console allows mobile users check virtual machine compute go even connected network protocol inspector discover report remoting capabilities vms hosts network company provides cloud computing desktop virtualization remote access systems management technologies vdiworks inc. offers software education healthcare financial services small-medium-sized business enterprise markets vdiworks inc. prior subsidiary clearcube technology inc. vdiworks received best emerging virtualization company award multiple times crn contribution commitment towards virtualization innovation awareness vdiworks virtual desktop platform vdi management suite connection brokering remoting protocol centralized management desktop security virtual desktop healthcare aggregates user environment servers replacing pcs hardy completely secure thin clients virtual desktops vdi represent next evolution healthcare pc vdiworks made remote access possible educational power virtualization removed limitations location single desktop dependency user access information whether class room restaurant home travelling
Distributed computing architecture
geexbox geexbox free linux distribution providing media center software suite personal computers geexbox 2.0 later uses xbmc media playback implemented live usb live cd options system need permanently installed hard drive modern operating systems would instead computer booted geexbox cd media playback desired reasonable approach need media playback services performing tasks computer users wish repurpose older computers media centers seeking free alternative windows xp media center edition unofficial port geexbox 1.x also runs wii geexbox 1.x versions also came utility called iso-generator allowed user customize geexbox discs following options configurable via
Computer architecture
mmx instruction set mmx single instruction multiple data simd instruction set designed intel introduced 1997 p5-based pentium line microprocessors designated pentium mmx technology developed similar unit introduced intel i860 earlier intel i750 video pixel processor mmx processor supplementary capability supported recent ia-32 processors intel vendors new york times described initial push including super bowl ads focused new generation glitzy multimedia products including videophones 3-d video games mmx subsequently extended several programs intel others 3dnow streaming simd extensions sse ongoing revisions advanced vector extensions avx mmx officially meaningless initialism trademarked intel unofficially initials variously explained standing newsweek described 57 new 'instructions etched microscopically onto face chip amd one numerous court battles intel produced marketing material intel indicating mmx stood matrix math extensions since initialism trademarked attempt invalidate intel trademark 1995 intel filed suit amd cyrix corp. misuse trademark mmx amd intel settled amd acknowledging mmx trademark owned intel intel granting amd rights use mmx trademark technology name processor name mmx defines eight registers called mm0 mm7 operations operate register 64 bits wide used hold either 64-bit integers multiple smaller integers packed format single instruction applied two 32-bit integers four 16-bit integers eight 8-bit integers mmx provides integer operations originally developed intel i860 use integer math made sense 2d 3d calculations required graphics cards much became common integer simd cpu became somewhat redundant graphical applications hand saturation arithmetic operations mmx could significantly speed digital signal processing applications avoid compatibility problems context switch mechanisms existing operating systems mmx registers aliases existing x87 fpu registers context switches would already save restore unlike x87 registers behave like stack mmx registers directly addressable random access operation involving floating point stack might also affect mmx registers vice versa aliasing makes difficult work floating point simd operations application maximize performance programmers often used processor exclusively one mode deferring relatively slow switch long possible 64-bit mmx register corresponds mantissa part 80-bit x87 register upper 16 bits x87 registers thus go unused mmx bits set ones making nans infinities floating point representation used applications decide whether particular register content intended floating point simd data software support mmx slow coming intel c compiler related development tools obtained intrinsics invoking mmx instructions intel released libraries common vectorized algorithms using mmx intel metrowerks attempted automatic vectorization compilers operations c programming language mapped poorly onto mmx instruction set custom algorithms 2000 typically still written assembly amd competing x86 microprocessor vendor enhanced intel mmx 3dnow instruction set 3dnow best known adding single-precision 32-bit floating-point support simd instruction-set among integer general enhancements following mmx intel next major x86 extension sse introduced pentium-iii family 1999 roughly year amd 3dnow introduced sse addressed core shortcomings mmx inability mix integer-simd ops floating-point ops creating new 128-bit wide register file xmm0–xmm7 new simd instructions like 3dnow sse focused exclusively single-precision floating-point operations 32-bit integer simd operations still performed using mmx register instruction set however new xmm register-file allowed sse simd-operations freely mixed either mmx x87 fpu ops sse2 introduced pentium 4 extended x86 simd instruction set integer 8/16/32 bit double-precision floating-point data support xmm register file sse2 also allowed mmx opcodes use xmm register operands extended even wider ymm zmm registers later sse revisions intel marvell xscale microprocessor core starting pxa270 include simd instruction set extension arm core called iwmmxt whose functions similar ia-32 mmx extension iwmmxt stands intel wireless mmx technology provides arithmetic logic operations 64-bit integer numbers software may choose instead perform two 32-bit four 16-bit eight 8-bit operations single instruction extension contains 16 data registers 64-bits eight control registers 32-bits registers accessed standard arm architecture coprocessor mapping mechanism iwmmxt occupies coprocessors 0 1 space opcodes clash opcodes earlier floating-point extension fpa later versions marvell arm processors supports wmmx wireless mmx wmmx2 wireless mmx2 support
Computer architecture
streaming simd extensions computing streaming simd extensions sse single instruction multiple data simd instruction set extension x86 architecture designed intel introduced 1999 pentium iii series central processing units cpus shortly appearance advanced micro devices amd 3dnow sse contains 70 new instructions work single precision floating point data simd instructions greatly increase performance exactly operations performed multiple data objects typical applications digital signal processing graphics processing intel first ia-32 simd effort mmx instruction set mmx two main problems re-used existing x87 floating point registers making cpus unable work floating point simd data time worked integers sse floating point instructions operate new independent register set xmm registers adds integer instructions work mmx registers sse subsequently expanded intel sse2 sse3 ssse3 sse4 supports floating point math wider applications mmx became popular addition integer support sse2 made mmx largely redundant code though performance increases attained situations using mmx parallel sse operations sse originally called katmai new instructions kni katmai code name first pentium iii core revision katmai project intel sought distinguish earlier product line particularly flagship pentium ii later renamed internet streaming simd extensions isse sse amd eventually added support sse instructions starting athlon xp duron morgan core processors sse originally added eight new 128-bit registers known codice_1 codice_2 amd64 extensions amd originally called x86-64 added eight registers codice_3 codice_4 extension duplicated intel 64 architecture also new 32-bit control/status register codice_5 registers codice_3 codice_4 accessible 64-bit operating mode sse used single data type xmm registers sse2 would later expand usage xmm registers include 128-bit registers additional machine states operating system must preserve across task switches disabled default operating system explicitly enables means os must know use codice_8 codice_9 instructions extended pair instructions save x86 sse register states support quickly added major ia-32 operating systems first cpu support sse pentium iii shared execution resources sse floating point unit fpu compiled application interleave fpu sse instructions side-by-side pentium iii issue fpu sse instruction clock cycle limitation reduces effectiveness pipelining separate xmm registers allow simd scalar floating point operations mixed without performance hit explicit mmx/floating point mode switching sse introduced scalar packed floating point instructions following simple example demonstrates advantage using sse consider operation like vector addition used often computer graphics applications add two single precision four-component vectors together using x86 requires four floating-point addition instructions corresponds four x86 fadd instructions object code hand following pseudo-code shows single 128-bit 'packed-add instruction replace four scalar addition instructions x86 instruction set extensions bios operating system application programmer test detect existence proper operation user application uptake x86 extensions slow even bare minimum baseline mmx sse support cases non-existent applications 10 years extensions became commonly available distributed computing accelerated use extensions scientific community—and many scientific applications refuse run unless cpu supports sse2 sse3 use multiple revisions application cope many different sets extensions available simplest way around x86 extension optimization problem software libraries applications begun support multiple extension types hinting full use available x86 instructions may finally become common 5 15 years instructions initially introduced processor id applications
Computer architecture
microreboot microrebooting technique used recover failures crash-only software systems instead rebooting whole system subsets fine-grain components restarted granularity components typically finer process level e.g. ejb-level java ee systems goal confining reboot fine-grain components threefold reduce amount time takes system return service minimize failure disruption system users preserve much in-memory application data possible concept proposed 2001 george candea armando fox former graduate student stanford university initially reduced practice systems satellite ground station control system java ee application server later formed basis design commercial systems like aster data systems ncluster
Operating systems
scalebase scalebase company sold software implement distributed mysql databases cloud computing software company located boston massachusetts area scalebase founded 2009 doron levari ram metser formerly ceo guardium database security company acquired ibm 2009 named ceo october 2012 october 2012 scalebase closed series b round 10.5 million bain capital ventures ascent venture partners original investor cedar fund scalearc raised 5.33 million december 2011 12 million new funding announced january 2013 led accell partners assets scalebase acquired scalearc august 2015 company scalebase provided two technology offerings one also called scalebase analysis genie scalebase software first released august 2011 scalebase distributed database cluster built mysql capability provides scalability availability benefits distributed database retaining relational database characteristics scalebase data distribution policy-based transparent scalebase provides visibility control variables impact data distribution policy scalebase software available amazon web services ec2 rds rackspace ibm cloud analysis genie software service analyzed schema queries purpose suggest data distribution policy uniquely tuned individual application requirements database workloads
Databases
data cluster computer file systems cluster allocation unit unit disk space allocation files directories reduce overhead managing on-disk data structures filesystem allocate individual disk sectors default contiguous groups sectors called clusters disk uses 512-byte sectors 512-byte cluster contains one sector whereas 4-kibibyte kib cluster contains eight sectors cluster smallest logical amount disk space allocated hold file storing small files filesystem large clusters therefore waste disk space wasted disk space called slack space cluster sizes small versus average file size wasted space per file statistically half cluster size large cluster sizes wasted space become greater however larger cluster size reduces bookkeeping overhead fragmentation may improve reading writing speed overall typical cluster sizes range 1 sector 512 b 128 sectors 64 kib cluster need physically contiguous disk may span one track sector interleaving used may even discontiguous within track confused fragmentation sectors still logically contiguous term cluster changed allocation unit dos 4.0 however term cluster still widely used
Computer file systems
dmarc dmarc domain-based message authentication reporting conformance email authentication protocol designed give email domain owners ability protect domain unauthorized use commonly known email spoofing purpose primary outcome implementing dmarc protect domain used business email compromise attacks phishing emails email scams cyber threat activities dmarc dns entry published receiving email server authenticate incoming email based instructions published domain owner within dns entry email passes authentication delivered trusted email fails check depending instructions held within dmarc record email could delivered quarantined rejected dmarc extends two existing mechanisms sender policy framework spf domainkeys identified mail dkim allows administrative owner domain publish policy dns records specify mechanism dkim spf employed sending email domain check codice_1 field presented end users receiver deal failures reporting mechanism actions performed policies dmarc defined rfc 7489 dated march 2015 informational dmarc policy allows sender domain indicate emails protected spf and/or dkim tells receiver neither authentication methods passes – reject message quarantine policy also specify email receiver report back sender domain messages pass and/or fail policies published public domain name system dns text txt records dmarc n't directly address whether email spam otherwise fraudulent instead dmarc require message pass dkim spf validation also pass alignment dmarc message fail even passes spf dkim fails alignment setting dmarc may positive impact deliverability legitimate senders dmarc operates checking domain message codice_1 field also called 5322.from aligned authenticated domain names either spf dkim alignment checks pass dmarc alignment test passes alignment may specified strict relaxed strict alignment domain names must identical relaxed alignment top-level organizational domain must match organizational domain found checking list public dns suffixes adding next dns label example a.b.c.d.example.com.au example.com.au organizational domain registrar offers names .com.au customers albeit time dmarc spec ietf working group domain boundaries nowadays organizational domain derived public suffix list like spf dkim dmarc uses concept domain owner entity entities authorized make changes given dns domain spf checks ip address sending server authorized owner domain appears smtp codice_3 command email address mail also called envelope-from 5321.mailfrom addition requiring spf check pass dmarc additionally checks 5321.mailfrom aligns 5322.from dkim allows parts email message cryptographically signed signature must cover field within dkim-signature mail header codice_4 domain codice_5 selector tags specify dns retrieve public key signature valid signature proves signer domain owner field n't modified since signature applied may several dkim signatures email message dmarc requires one valid signature domain codice_4 tag aligns sender domain stated codice_1 header field dmarc records published dns subdomain label codice_8 example codice_9 compare spf codice_10 dkim codice_11 content txt resource record consists codice_12 tags separated semicolons similar spf dkim example codice_13 version codice_14 policy codice_15 subdomain policy codice_16 percent bad emails apply policy codice_17 uri send aggregate reports example entity controlling example.com dns domain intends monitor spf and/or dkim failure rates n't expect emails sent subdomains example.com note subdomain publish dmarc record receivers must check falling back organizational domain record dmarc capable producing two separate types reports aggregate reports sent address specified following codice_17 forensic reports emailed address following codice_19 tag mail addresses must specified uri mailto format e.g nowiki mailto worker example.net /nowiki multiple reporting addresses valid must full uri format separated comma target email addresses belong external domains case target domain set dmarc record say agrees receive otherwise would possible exploit reporting spam amplification example say codice_20 receives mail message codice_21 wishes report finds codice_22 looks confirming dns record namespace administered target like aggregate reports sent xml files typically per day subject mentions report domain policy-publishing sender mail messages reported submitter entity issuing report payload attachment long filename consisting bang-separated elements report-issuing receiver begin end epochs reported period unix-style time stamps optional unique identifier extension depends possible compression used codice_23 example codice_24 xml content consists header containing policy report based report metadata followed number records records put database relation viewed tabular form xml schema defined appendix c specifications raw record exemplified dmarc.org stick relational example better conveys nature data dmarc records also directly transformed html applying xsl stylesheet rows grouped source ip authentication results passing count group leftmost result columns labelled spf dkim show dmarc-wise results either pass fail taking alignment account rightmost ones similar labels show name domain claims participate sending message parentheses authentication status claim according original protocol spf dkim regardless identifier alignment right side spf appear twice codice_25 test codice_26 test dkim appear signature present message example first row represents main mail flow example.org second row dkim glitch signature breakage due minor alteration transit third fourth rows show typical failures modes forwarder mailing list respectively dmarc authentication failed last row could affected message disposition example.org specified strict policy disposition reflects policy published actually applied messages none quarantine reject along shown table dmarc provides policy override reasons receiver apply policy different one requested already provided specification forensic reports also known failure reports generated real time consist redacted copies individual emails failed spf dkim based upon value specified codice_27 tag format extension abuse reporting format resembles regular bounces contain either message/rfc822 text/rfc822-headers several different types email forwarding may break spf mailing lists frequent cause legitimate breakage original author domain dkim signature routinely change spf-authenticated domain therefore break dmarc alignment number workarounds possible mailing list software packages working solutions one popular least intrusive workarounds consists rewriting codice_1 header field original author address added codice_30 field rewriting range appending codice_31 domain name allocating temporary user id forward replies list opaque id used keeps user real email address private list addition display name changed show author list list operator examples would result respectively one last line codice_30 designed order accommodate reply-to-author functionality case reply-to-list function covered preceding change codice_1 header field way original meaning fields reversed altering author fair general break expected relationship meaning appearance datum also breaks automated use communities use mailing lists coordinate work deploy tools use codice_1 field attribute authorship attachments wrapping message works nicely use email client understands wrapped messages change perhaps obvious solution except seem legally due countries routinely losing spf authentication may render overall authentication fragile making changes codice_1 header field pass dkim alignment may bring message compliance rfc 5322 section 3.6.2 'from field specifies author message mailbox es person system responsible writing message mailbox refers author email address codice_36 header available indicate email sent behalf another party dmarc checks policy domain ignores sender domain adsp dmarc reject using sender field non-technical basis many user agents n't display recipient draft dmarc specification maintained since 30 january 2012 october 2013 gnu mailman 2.1.16 released options handle posters domain dmarc policy codice_37 change tried anticipate interoperability issues expected case restrictive policies applied domains human users opposed purely transactional mail domains april 2014 yahoo changed dmarc policy codice_37 thereby causing misbehavior several mailing lists days later aol also changed dmarc policy codice_37 moves resulted significant amount disruption mailbox providers accused forcing costs security failures onto third parties ietf working group formed august 2014 order address dmarc issues starting interoperability concerns possibly continuing revised standard specification documentation meanwhile existing dmarc specification reached editorial state agreed upon implemented many published march 2015 independent submission stream informational non-standard category rfc 7489 march 2017 federal trade commission published study dmarc usage businesses study found 10 569 businesses significant online presence publish strict dmarc policies contributors dmarc specification include
Computer security
panda cloud antivirus panda cloud antivirus antivirus software developed panda security free paid version available cloud-based sense files scanned remote server without using processing power user machine cloud technology based panda collective intelligence run constantly providing protection viruses malicious websites slowing system extent system scan according panda security panda cloud antivirus able detect viruses trojans worms spyware dialers hacking tools hacker security risks panda cloud antivirus relies collective intelligence cloud up-to-date information normally uses internet connection access up-to-date information internet accessed use local cache common threats circulation april 2009 review found panda cloud antivirus 1.0 clean fast simple easy use good detection rates review scored panda 100.00 malware detection 100.0 malicious url detection overall score 100 strong protection factor considering software version 1.0 released november 10 2009 pc magazine reviewed panda cloud antivirus gave editor choice award best av techradar review states think panda cloud antivirus best viewed defense tool rather utility cleaning system already riddled infection free edition panda cloud antivirus released license usage exclusively allowed private households state schools non-governmental non-profit organizations
Computer security
microsoft personal web server microsoft personal web server pws scaled-down web server software windows operating systems fewer features microsoft internet information services iis functions superseded iis visual studio microsoft officially supports pws windows 95 windows 98 windows 98 se windows nt 4.0 prior release windows 2000 pws available free download well included windows distribution cds pws 4.0 last version found windows 98 cd windows nt 4.0 option pack personal web server originally created vermeer technologies company created microsoft frontpage acquired microsoft installed frontpage versions 1.1 98 well nt workstation 4.0 shipped peer web services based iis 2.0 3.0 iis 4.0 renamed personal web server consistent name used 95/98 since windows 2000 pws renamed iis name used server versions windows standard windows component windows windows xp home edition support neither pws iis although pws installed windows editions windows xp iis included standard microsoft visual studio 2005 pws useful developing web applications localhost deploying production web server ide visual studio 2005 later versions contains built-in lightweight web server development purposes ftp smtp http usual web languages php perl supported pws also supports basic cgi common gateway interface conventions subset classic asp using technologies web applications running pws capable performing interpreting database queries results microsoft also produced version personal web server macintosh based code acquired acquisition resnova software november 1996
Web technology
grum botnet grum botnet also known alias tedroo reddyb botnet mostly involved sending pharmaceutical spam e-mails world largest botnet grum traced back early 2008 time shutdown july 2012 grum reportedly world 3rd largest botnet responsible 18 worldwide spam traffic grum relies two types control servers operation one type used push configuration updates infected computers used tell botnet spam emails send july 2010 grum botnet consisted estimated 560,000–840,000 computers infected grum rootkit botnet alone delivered 39.9 billion spam messages march 2010 equating approximately 26 total global spam volume temporarily making world then-largest botnet late 2010 botnet seemed growing output increased roughly 51 comparison output 2009 early 2010 used panel written php control botnet july 2012 malware intelligence company published analysis botnet command control servers located netherlands panama russia later reported dutch colo/isp soon seized two secondary servers responsible sending spam instructions existence made public within one day panamanian isp hosting one grum primary servers followed suit shut server cybercriminals behind grum quickly responded sending instructions six newly established servers ukraine fireeye connected spamhaus cert-gib anonymous researcher shut remaining six c c servers officially knocking botnet sinkhole running former ip addresses grumbot c c servers feed sinkhole processed via shadowserver abusix inform point contact isp infected ip addresses isp asked contact customers infections malware cleaned shadowserver.org inform users service per day abusix sends x-arf extended version abuse reporting format report every hour
Computer security
airport security airport security refers techniques methods used attempt protect passengers staff aircraft airport property accidental/malicious harm crime threats aviation security combination human material resources safeguard civil aviation unlawful interference unlawful interference could acts terrorism sabotage threat life property communication false threat bombing etc large numbers people pass airports every day presents potential targets terrorism forms crime number people located one place similarly high concentration people large airliners increases potentially high death rate attacks aircraft ability use hijacked airplane lethal weapon may provide alluring target terrorism september 11 attacks airport security attempts prevent threats potentially dangerous situations arising entering country airport security succeed chances dangerous situation illegal items threats entering aircraft country airport greatly reduced airport security serves several purposes protect airport country threatening events reassure traveling public safe protect country people monte r. belger u.s. federal aviation administration notes goal aviation security prevent harm aircraft passengers crew well support national security counter-terrorism policy countries may agency protects airports australia australian federal police polices airport countries protection controlled state local level primary personnel vary include resources may include incidents result travelers carrying either weapons items could used weapons board aircraft hijack plane travelers screened metal detectors and/or millimeter wave scanners explosive detection machines used include x-ray machines explosives trace-detection portal machines a.k.a puffer machines united states tsa working new scanning machines still effective searching objects n't allowed airplanes n't depict passengers state undress find embarrassing explosive detection machines also used carry-on checked baggage detect volatile compounds given explosives using gas chromatography recent development controversial use backscatter x-rays detect hidden weapons explosives passengers devices use compton scattering require passenger stand close flat panel produce high resolution image technology released israel early 2008 allows passengers pass metal detectors without removing shoes process required walk-through gate detectors reliable detecting metal shoes lower body extremities alternately passengers step fully shoed onto device scans 1.2 seconds objects small razor blade countries specially trained individuals may engage passengers conversation detect threats rather solely relying equipment find threats single backscatter scan exposes target 0.05 0.1 microsievert radiation comparison exposure standard chest x-ray almost 100 times higher generally people screened airport security areas exit gates aircraft located areas often called secure sterile airside passengers discharged airliners sterile area usually re-screened disembarking domestic flight however still subject search time airport food outlets started using plastic glasses utensils opposed glasses made glass utensils made metal reduce usefulness items weapons united states non-passengers allowed concourses meet arriving friends relatives gates greatly restricted due terrorist attacks non-passengers must obtain gate pass enter secure area airport common reasons non-passenger may obtain gate pass assist children elderly well attending business meetings take place secure area airport united states least 24 hours notice generally required planning attend business meeting inside secure area airport countries australia restrict non-travellers accessing airside area however non-travellers typically subject security scans travellers sensitive areas airports including airport ramps operational spaces restricted general public called sida security identification display area spaces require special qualifications enter systems consist physical access control gates passive systems monitor people moving restricted areas sound alert restricted area entered throughout world dozen airports instituted version trusted traveler program proponents argue security screening made efficient detecting people threats searching argue searching trusted verified individuals take amount time critics argue programs decrease security providing easier path carry contraband another critical security measure used several regional international airports fiber optic perimeter intrusion detection systems security systems allow airport security locate detect intrusion airport perimeter ensuring real-time immediate intrusion notification allows security personnel assess threat track movement engage necessary security procedures notably utilised dulles international airport u.s. military jfpass world first terrorist attack flight cubana flight 455 october 6 1976 airliner flying barbados jamaica brought two time bombs killing 73 people evidence implicated several central intelligence agency-linked anti-castro cuban exiles members venezuelan secret police disip including luis posada carriles single deadliest airline catastrophe resulting failure airport security detect onboard bomb air india flight 182 1985 killed 329 people another onboard bomb slipped airport security one pan flight 103 1988 killed 270 people 259 plane 11 residents lockerbie scotland another notable failure 1994 bombing philippine airlines flight 434 turned test run planned terrorist attack called operation bojinka explosion small killing one person plane made emergency landing operation bojinka discovered foiled manila police 1995 may 30 1972 three members japanese red army undertook terrorist attack popularly called lod airport massacre lod airport known ben gurion international airport tel aviv firing indiscriminately automatic firearms throwing grenades managed kill 24 people injure 78 others neutralized one suicide one three terrorists kozo okamoto survived incident rome vienna airport attacks december 1985 two instances airport security failures attacks left 20 people dead gunmen threw grenades opened fire travelers el al airline ticket counters september 11 attacks widely recognized terrorist attacks recent times involving air travel morning september 11 2001 19 members islamic terrorist group al-qaeda took control four airplanes east coast united states deliberately crashed two world trade center towers new york city third pentagon arlington county virginia fourth plane crashed field near shanksville pennsylvania reaching washington d.c. intended target either u.s. capitol white house attacks resulted deaths 2,996 people including 245 civilians law enforcement officer 19 hijackers board four airplanes july 5 2002 gunman opened fire los angeles international airport israel el al ticket counter shooter killed two people injured four august 10 2006 security airports united kingdom canada united states raised significantly due uncovering british authorities terror plot aimed detonating liquid explosives flights originating countries also notable first time u.s. terror alert level ever reached red incident also led tighter restrictions carrying liquids gels hand luggage eu canada united states. ref name= 1546/2006 /ref restrictions involving airport security determined transport canada implemented canadian air transport security authority catsa conjunction airport operator since september 11 attacks well air india bombing 1985 incidents airport security tightened canada order prevent attacks canadian airspace catsa uses x-ray machines verify contents carry-ons well metal detectors explosive trace detection etd equipment random physical searches passengers pre-board screening points x-ray machines ctx machines high-resolution x-rays etds also used scan checked bags checked baggage always x-rayed major commercial airports catsa launched restricted area identity card raic program january 2007 raic world first dual biometric access control system airports program replaces old airport restricted area passes issued airport employees security checks canadian security intelligence service royal canadian mounted police rcmp transport canada new cards issued checks conducted contain biometric information fingerprints iris scans belonging person issued raic catsa responsible pre-board passenger random non-passenger screening contract third-party service providers g4s securitas gardaworld train manage employ screening officers addition individual airport authorities privatized 1990s canadian government responsible general airport security rather catsa normally contract private companies case large airports pay small contingent local police officers remain site well safety security canada airports provided local police forces rcmp used provide service airports remains today regulation ec 300/2008 european parliament council establishes common rules european union protect civil aviation acts unlawful interference regulation provisions apply airports parts airports located eu country used exclusively military purposes provisions also apply operators including air carriers providing services aforementioned airports also applies entities located inside outside airport premises providing services airports standards regulation 300/2008 implemented commission regulation eu 2015/1998 regulation 2320/2002 2002 introduced requirement security checks passenger flights also domestic eu countries checks domestic flights around 2005 introducing full security checks took time since terminals might need expansion passenger luggage freight security checking security guard duties outsourced contractors general public security responsibility finnish police airport unit helsinki airport airport unit criminal investigation canine tepo terrorist bomb squad ptr police customs border guard intelligence component furthermore units finnish border guard units airports often arrest wanted individuals fugitives border finnish customs seizes e.g weapons false documents explosives addition wanted individuals french security stepped since terrorist attacks france 1986 response france established vigipirate program program uses troops reinforce local security increases requirements screenings id checks since 1996 security check-points transferred police nationale/gendarmerie de l'air private companies hired airport authorities member european economic area iceland adopted ec regulation 300/2008 national law thus complies eu standards airport security international flights domestic flights within icelandic territory however exempted security rules exemption granted eea joint committee citing geographical remoteness country well low population density small size aircraft used domestic operations airport security netherlands provided koninklijke marechaussee kmar royal military constabulary airport security spain provided police forces well private security guards policía nacional provides general security well passport international airports documentation checking catalonia basque country mossos d'esquadra ertzaintza respectively replaced policía nacional except documentation functions guardia civil handles security customs checking often aided private security guards local police provide security traffic control outside airport building security measures controlled state owned company aena bound european commission regulations european union countries airport security handled security guards provided airport police assistance needed airport fire fighters also security guards swedish transport agency decides rules check based international regulations airports generally defined law protected objects give guards extra authority like demanding identity documents search people belongings sweden traditionally seen low-crime country little need security checks sweden introduced security checks international departures international regulations demanded around 1970s/1980s september 2001 decision introduce security checks also domestic flights took years implement domestic airports terminals prepared room department transport dft governing authority airport security united kingdom civil aviation authority caa also responsible certain security regulatory functions september 2004 home office dft started initiative called multi agency threat risk assessment matra piloted five united kingdom major airports — heathrow birmingham east midlands airport newcastle glasgow following successful trials scheme rolled across 44 airports since september 11 attacks new york united kingdom assessed high risk country due support united states invasion afghanistan iraq january 7 2008 travelers longer limited single piece carry-on luggage uk major airports currently hand luggage limited size weight dft/caa although airlines impose rules uk trialed controversial new method screening passengers improve airport security using backscatter x-ray machines provide 360-degree view person well see clothes right skin bones longer used replaced millimeter wave scanners shows hidden items showing body passenger hong kong international airport secured hong kong police force aviation security company avseco within police force airport district responsible safety security airport region airport security units deployed around airport armed h k mp5 a3 sub-machine guns glock 17 pistols security restricted area responsibility police avseco airport control airport authority hong kong aahk security power delegated avseco staffs persons baggages carried must x-rayed checked security screening points avseco exceptions tenant restricted area immigration department check incomers passport identities customs excise department check passengers crews luggage discourage smuggling drugs contraband entering hong kong india stepped airport security 1999 kandahar hijacking central industrial security force paramilitary organisation charge airport security regulatory framework bureau civil aviation security ministry civil aviation cisf formed airport security group protect indian airports every airport given apsu airport security unit trained unit counter unlawful interference civil aviation apart cisf every domestic airline security group looks aircraft security terrorist threats narcotics main threats indian airports another problem airports face proliferation slums around airport boundaries places like mumbai boarding additional searching hand luggage likely moreover cisf many duties context aviation security cargo security screening done regulated agents airlines airports security staff tested certified bureau civil aviation security bcas aviation security regulator el al airlines headquartered israel last hijacking occurred july 23 1968 plane departing ben gurion airport outside tel aviv ever hijacked 1972 terrorists japanese red army launched attack led deaths least 24 people lod airport since security airport relies number fundamentals including heavy focus raphael ron former director security ben gurion airport terms human factor may generalized inescapable fact terrorist attacks carried people found stopped effective security methodology december 27 1985 terrorists simultaneously attacked el al ticket counters rome italy vienna austria airports using machine guns hand grenades nineteen civilians killed many wounded response israel developed methods stop massacres drastically improved security measures around israeli airports even promised provide plainclothes armed guards foreign airport last successful airline-related terrorist attack 1986 security agent found suitcase full explosives initial screening process bag make board injure 13 detonating terminal part focus so-called human factor israeli security officers interrogate travelers using racial profiling singling appear arab based name physical appearance additionally passengers even appear arab descent questioned traveling israel followed several general questions trip order search inconsistencies although numerous civil rights groups demanded end profiling israel maintains effective unavoidable according ariel merari israeli terrorism expert would foolish use profiling everyone knows terrorists come certain ethnic groups likely muslim young potential threat justifies inconveniencing certain ethnic group passengers leaving israel checked computerized list computers maintained israeli ministry interior connected israeli police fbi canadian security intelligence service csis scotland yard shin bet interpol order catch suspects others leaving country illegally despite tight security incident occurred november 17 2002 man apparently slipped airport security ben gurion airport pocketknife attempted storm cockpit el al flight 581 en route tel aviv istanbul turkey injuries reported attacker subdued guards hidden among passengers 15 minutes plane landed safely turkey authorities shut ben gurion time attack reassess security situation investigation opened determine man israeli arab managed smuggle knife past airport security conference may 2008 united states department homeland security secretary michael chertoff told reuters interviewers united states seek adopt israeli security measures domestic airports left post january 2009 mere 6 months statement may may enough time implement limited focus american airports turning israeli government israeli-run firms help upgrade security post-9/11 world israeli officials toured los angeles airport november 2008 re-evaluate airport making security upgrade recommendations 2006 calling ben gurion world safest airport antonio villaraigosa mayor los angeles implemented israeli review order bring state-of-the-art technology tactical measures help secure lax considered state primary terrorist target singled al qaeda network new age security solutions led former director security ben gurion based washington d.c. consults aviation security boston logan international airport u.s. airports incorporate israeli tactics systems include port oakland san diego county regional airport authority israelis legendary security opportunity see firsthand importantly theory behind said steven grossman director aviation port oakland impressed briefing presented israelis suggested trip israel u.s. branch airports council international order gain deeper understanding methods employed israeli airport security law enforcement pakistan airports security force asf responsible protecting airports facilities planes asf safeguards civil aviation industry unlawful interference adopting counter terrorism measures preventing crime maintaining law order within limits airports pakistan security country two international passenger airports comes purview airport police division singapore police force although resources concentrated singapore changi airport scheduled passenger traffic dominate seletar airport specializes handling non-scheduled training flights seen posing less security issue since september 11 attacks naming changi airport terrorism target jemaah islamiyah airport security stepped roving patrol teams two soldiers police officer armed automatic weapons patrol terminals random departing passengers checked entrance gate rather immigration clearance unlike hong kong international airport security measure easily noticed presence x-ray machines metal detectors every gate normally seen airports assisting state organizations security services provided ground handlers namely certis cisco singapore airport terminal services sats security services aetos security management private limited formed merger changi international airport services airport security unit companies become single island-wide auxiliary police company officers duties include screening luggage controlling movement restricted areas since 2005 upgrade screening technology rising security concerns led luggage-screening processes conducted behind closed doors plans also place install 400 cameras monitor airport discourage bomb attacks similar 2005 songkhla bombings southern thailand hat yai international airport targeted tenders incorporate system called late september 2005 since 8 may 2007 liquid restrictions 100 ml cap enforced following 2006 transatlantic aircraft plot passengers advised check liquids gels aerosols 100 ml failing confiscated airport security post back oneself anything security areas allowed general practice unacceptable materials also confiscated post back excluding nail clippers nail files umbrellas racquets prior 1970s american airports minimal security arrangements prevent acts terrorism measures introduced starting late 1960s several high-profile hijackings sky marshals introduced 1970 insufficient numbers protect every flight hijackings continued take place november 10 1972 trio hijackers threatened fly southern airways flight 49 nuclear reactor oak ridge national laboratory direct response incident federal aviation administration required airlines begin screening passengers carry-on baggage january 5 1973 screening generally contracted private security companies private companies would bid contracts airline operational control departure concourse controlled given checkpoint would hold contract although airline would control operation checkpoint oversight authority held faa c.f.r title 14 restrictions permit relevant airport authority exercise oversight checkpoint operations 1974 film parallax view shows early airport security checkpoint operation september 11 attacks prompted even tougher regulations limiting number types items passengers could carry board aircraft requiring increased screening passengers fail present government-issued photo id aviation transportation security act generally required november 19 2002 passenger screening must conducted federal employees result passenger baggage screening provided transportation security administration tsa part u.s. department homeland security provisions improve technology detecting explosives included terrorism prevention act 2004 often security category x airports u.s. largest busiest measured volume passenger traffic provided private contractors high volume passenger traffic category x airports considered vulnerable targets terrorism increase security screening airports saw long queues security checks alleviate airports created premium lines passengers traveling first business class elite members particular airline frequent flyer program screening passengers observation techniques spot program operating u.s. airports us specific
Computer security
l0pht l0pht heavy industries pronounced loft hacker collective active 1992 2000 located boston massachusetts area l0pht one first viable hackerspaces us pioneer responsible disclosure group famously testified front congress 1998 topic ‘ weak computer security government ’ second character name originally slashed zero symbol used old teletypewriters character mode operating systems mean zero modern online name including domain name therefore l0pht zero letter ø origin l0pht traced brian oblivion count zero two founding members sharing common loft space south boston wives ran hat business one half space experimented personal computers equipment purchased flea mit mit items obtained dumpster diving local places interest founded 1992 l0pht quickly became location members store computer hardware work various projects time members l0pht quit day jobs start business venture named l0pht heavy industries hacker think tank business released numerous security advisories also produced widely used software tools l0phtcrack password cracker windows nt pocsag decoder cd software collections 1997 august 8–10 mudge brian oblivion kingpin space rogue stefan weld pond john tan l0pht discussed recent projects accomplishments windows nt new projects emerging trends shortcomings technologies q session beyond hope puck building new york city october 1999 l0pht featured lengthy article new york times sunday magazine article jeffrey hunker nsc director information protection said l0pht objective basically help improve state art security gadfly speak january 2000 l0pht heavy industries merged startup stake completing l0pht slow transition underground organization whitehat computer security company symantec announced acquisition stake september 16 2004 completed transaction october 8 year march 14 2008 several members l0pht sat panel standing-room-only group infosec professionals source boston present weld pond john tan mudge space rogue silicosis dildog may 19 1998 seven members l0pht brian oblivion kingpin mudge space rogue stefan von neumann john tan weld pond famously testified congress united states could shut entire internet 30 minutes washington post referred response tragedy missed opportunity four members original group space rogue weld pond kingpin mudge held briefing entitled “ disaster foretold — ignored ” revisiting first-ever congressional cybersecurity hearing hosted congressional internet caucus academy briefing held may 22 2018 almost exactly 20 years original testimony streamed live via facebook defcon 26 hacking conference held august 10 2018 las vegas seven l0pht members sat panel entitled l0pht testimony 20 years later things afraid ask among things panel encouraged attendees keep hacking stay side law kept jail general counsel national security agency glenn s. gerstell quoted testimony l0pht ’ hearing keynote american bar association ’ 28th annual review field national security law conference november 1 2018 l0pht occupied physical space real expenses electricity phone internet access rent early l0pht history costs evenly divided among l0pht members fact l0pht originally shared space hat-making business run spouses brian oblivion count zero rental cost divided amongst soon subsidized profits made selling old hardware monthly mit electronic flea market summer occasionally shell accounts offered low cost l0pht.com server selected individuals individuals access l0pht.com server members l0pht one first physical products sold profit l0pht pocsag decoder kit sold kit assembled form subsequently whacked mac archives transferred cd-rom sale soon followed cd copies black crawling system archives command line version l0phtcrack password cracker windows nt given away free gui version sold commercial product followed creation hacker news network website host advertisements however even sources income l0pht barely broke even eventually began custom security coding companies like nfr january 2009 l0phtcrack acquired original authors zatko wysopal rioux symantec l0phtcrack 6 released source boston conference march 11 2009 l0phtcrack 6 contains support 64-bit windows platforms well upgraded rainbow tables support l0pht membership varied included various times
Computer security
history operating systems computer operating systems oses provide set functions needed used application programs computer links needed control synchronize computer hardware first computers operating system every program needed full hardware specification run correctly perform standard tasks drivers peripheral devices like printers punched paper card readers growing complexity hardware application programs eventually made operating systems necessity everyday use earliest computers mainframes lacked form operating system user sole use machine scheduled period time would arrive computer program data often punched paper cards magnetic paper tape program would loaded machine machine would set work program completed crashed programs could generally debugged via control panel using dials toggle switches panel lights symbolic languages assemblers compilers developed programmers translate symbolic program-code machine code previously would hand-encoded later machines came libraries support code punched cards magnetic tape would linked user program assist operations input output genesis modern-day operating system however machines still ran single job time cambridge university england job queue one time washing line tapes hung different colored clothes-pegs indicate job-priority machines became powerful time run programs diminished time hand equipment next user became large comparison accounting paying machine usage moved checking wall clock automatic logging computer run queues evolved literal queue people door heap media jobs-waiting table batches punch-cards stacked one top reader machine able select sequence magnetic tape drives processed tapes program developers originally access run jobs machine supplanted dedicated machine operators looked machine less less concerned implementing tasks manually commercially available computer centers faced implications data lost tampering operational errors equipment vendors put pressure enhance runtime libraries prevent misuse system resources automated monitoring needed cpu usage counting pages printed cards punched cards read disk storage used signaling operator intervention required jobs changing magnetic tapes paper forms security features added operating systems record audit trails programs accessing files prevent access production payroll file engineering program example features building towards repertoire fully capable operating system eventually runtime libraries became amalgamated program started first customer job could read customer job control execution record usage reassign hardware resources job ended immediately go process next job resident background programs capable managing multistep processes often called monitors monitor-programs term operating system established underlying program offering basic hardware-management software-scheduling resource-monitoring may seem remote ancestor user-oriented oses personal computing era shift meaning os early automobiles lacked speedometers radios air-conditioners later became standard optional software features became standard features every os package although applications database management systems spreadsheets remain optional separately priced led perception os complete user-system integrated graphical user interface utilities applications text editors file managers configuration tools true descendant early operating systems called kernel technical development circles old restricted sense os persists continued active development embedded operating systems kinds devices data-processing component hand-held gadgets industrial robots real-time control-systems run user applications front-end embedded os device today far removed one might think ancestor 1950s broader categories systems application software discussed computer software article first operating system used real work gm-naa i/o produced 1956 general motors research division ibm 704 early operating systems ibm mainframes also produced customers early operating systems diverse vendor customer producing one operating systems specific particular mainframe computer every operating system even vendor could radically different models commands operating procedures facilities debugging aids typically time manufacturer brought new machine would new operating system applications would manually adjusted recompiled retested state affairs continued 1960s ibm already leading hardware vendor stopped work existing systems put effort developing system/360 series machines used instruction input/output architecture ibm intended develop single operating system new hardware os/360 problems encountered development os/360 legendary described fred brooks mythical man-month —a book become classic software engineering performance differences across hardware range delays software development whole family operating systems introduced instead single os/360 ibm wound releasing series stop-gaps followed two longer-lived operating systems ibm maintained full compatibility past programs developed sixties still run z/vse developed dos/360 z/os developed mft mvt change ibm also developed tss/360 time-sharing system system/360 model 67 overcompensating perceived importance developing timeshare system set hundreds developers work project ended bloated buggy project took long boot crash ended project without releasing several operating systems ibm s/360 s/370 architectures developed third parties including michigan terminal system mts music/sp control data corporation developed scope operating systems 1960s batch processing later developed mace operating system time sharing basis later kronos cooperation university minnesota kronos later nos operating systems developed 1970s supported simultaneous batch timesharing use like many commercial timesharing systems interface extension dtss time sharing system one pioneering efforts timesharing programming languages late 1970s control data university illinois developed plato system used plasma panel displays long-distance time sharing networks plato remarkably innovative time shared memory model plato tutor programming language allowed applications real-time chat multi-user graphical games univac 1107 univac first commercial computer manufacturer produced exec operating system computer sciences corporation developed exec ii operating system delivered univac exec ii ported univac 1108 later univac developed exec 8 operating system 1108 basis operating systems later members family like early mainframe systems exec exec ii batch-oriented system managed magnetic drums disks card readers line printers exec 8 supported batch processing on-line transaction processing 1970s univac produced real-time basic rtb system support large-scale time sharing also patterned dartmouth basic system burroughs corporation introduced b5000 1961 mcp master control program operating system b5000 stack machine designed exclusively support high-level languages software even lowest level operating system written directly machine language assembly language mcp first os written entirely high-level language espol dialect algol 60 although espol specialized statements syllable b5000 instruction set mcp also introduced many ground-breaking innovations one first commercial implementations virtual memory rewrite mcp b6500 still use today unisys clearpath/mcp line computers ge introduced ge-600 series general electric comprehensive operating supervisor gecos operating system 1962 honeywell acquired ge computer business renamed general comprehensive operating system gcos honeywell expanded use gcos name cover operating systems 1970s though many computers nothing common earlier ge 600 series operating systems derived original gecos project mac mit working ge bell labs developed multics introduced concept ringed security privilege levels digital equipment corporation developed tops-10 pdp-10 line 36-bit computers 1967 widespread use unix tops-10 particularly popular system universities early arpanet community bolt beranek newman developed tenex modified pdp-10 supported demand paging another popular system research arpanet communities later developed dec tops-20 scientific data systems/xerox data systems developed several operating systems sigma series computers basic control monitor bcm batch processing monitor bpm basic time-sharing monitor btm later bpm btm succeeded universal time-sharing system uts designed provide multi-programming services online interactive user programs addition batch-mode production jobs succeeded cp-v operating system combined uts heavily batch-oriented xerox operating system digital equipment corporation created several operating systems 16-bit pdp-11 machines including simple rt-11 system time-sharing rsts operating systems rsx-11 family real-time operating systems well vms system 32-bit vax machines several competitors digital equipment corporation data general hewlett-packard computer automation created operating systems one max iii developed modular computer systems modcomp ii modcomp iii computers characterised target market industrial control market fortran libraries included one enabled access measurement control devices ibm key innovation operating systems class call mid-range cpf system/38 capability-based addressing used machine interface architecture isolate application software operating system hardware dependencies including even details address size register size included integrated rdbms succeeding os/400 as/400 files objects different types objects persist large flat virtual memory called single-level store i5/os later ibm iseries continue line operating system unix operating system developed bell laboratories late 1960s originally pdp-7 later pdp-11 essentially free early editions easily obtainable easily modified achieved wide acceptance also became requirement within bell systems operating companies since written c language language ported new machine architecture unix also able ported portability permitted become choice second generation minicomputers first generation workstations widespread use exemplified idea operating system conceptually across various hardware platforms later became one roots free software open-source software operating system projects including gnu linux berkeley software distribution apple macos also based unix via nextstep freebsd pick operating system another operating system available wide variety hardware brands commercially released 1973 core basic-like language called data/basic sql-style database manipulation language called english licensed large variety manufacturers vendors early 1980s observers saw pick operating system strong competitor unix beginning mid-1970s new class small computers came onto marketplace featuring 8-bit processors typically mos technology 6502 intel 8080 motorola 6800 zilog z80 along rudimentary input output interfaces much ram practical systems started kit-based hobbyist computers soon evolved essential business tool many eight-bit home computers 1980s bbc micro commodore 64 apple ii series atari 8-bit amstrad cpc zx spectrum series others could load third-party disk-loading operating system cp/m geos generally used without one built-in operating systems designed era floppy disk drives expensive expected used users standard storage device tape drive using standard compact cassettes computers shipped built-in basic interpreter rom also served crude command line interface allowing user load separate disk operating system perform file management commands load save disk popular home computer commodore 64 notable exception dos rom disk drive hardware drive addressed identically printers modems external devices furthermore systems shipped minimal amounts computer memory—4-8 kilobytes standard early home computers—as well 8-bit processors without specialized support circuitry like mmu even dedicated real-time clock hardware complex operating system overhead supporting multiple tasks users would likely compromise performance machine without really needed systems largely sold complete fixed hardware configuration also need operating system provide drivers wide range hardware abstract away differences video games even available spreadsheet database word processors home computers mostly self-contained programs took machine completely although integrated software existed computers usually lacked features compared standalone equivalents largely due memory limitations data exchange mostly performed standard formats like ascii text csv specialized file conversion programs since virtually video game consoles arcade cabinets designed built 1980 true digital machines based microprocessors unlike earlier pong clones derivatives carried minimal form bios built-in game colecovision sega master system snk neo geo modern-day game consoles videogames starting pc-engine minimal bios also provides interactive utilities memory card management audio video cd playback copy protection sometimes carry libraries developers use etc cases however would qualify true operating system notable exceptions probably dreamcast game console includes minimal bios like playstation load windows ce operating system game disk allowing easily porting games pc world xbox game console little disguised intel-based pc running secret modified version microsoft windows background furthermore linux versions run dreamcast later game consoles well long sony released kind development kit called net yaroze first playstation platform provided series programming developing tools used normal pc specially modified black playstation could interfaced pc download programs operations require general functional os platforms involved general said videogame consoles arcade coin-operated machines used built-in bios 1970s 1980s 1990s playstation era beyond started getting sophisticated point requiring generic custom-built os aiding development expandability development microprocessors made inexpensive computing available small business hobbyist turn led widespread use interchangeable hardware components using common interconnection s-100 ss-50 apple ii isa pci buses increasing need standard operating systems control important early oses machines digital research cp/m-80 8080 8085 z-80 cpus based several digital equipment corporation operating systems mostly pdp-11 architecture microsoft first operating system mdos/midas designed along many pdp-11 features microprocessor based systems ms-dos pc dos supplied ibm designed similar cp/m-80 machines small boot program rom loaded os disk bios ibm-pc class machines extension idea accreted features functions 20 years since first ibm-pc introduced 1981 decreasing cost display equipment processors made practical provide graphical user interfaces many operating systems generic x window system provided many unix systems graphical systems apple classic mac os macos radio shack color computer os-9 level ii/multivue commodore amigaos atari tos ibm os/2 microsoft windows original gui developed xerox alto computer system xerox palo alto research center early 1970s commercialized many vendors throughout 1980s 1990s since late 1990s three operating systems widespread use personal computers apple inc. macos open source linux microsoft windows since 2005 apple transition intel processors developed mainly x86 platform although macos retained powerpc support 2009 linux remains ported multitude architectures including ones 68k pa-risc dec alpha long superseded production sparc mips used servers embedded systems longer desktop computers operating systems amigaos os/2 remain use mainly retrocomputing enthusiasts specialized embedded applications early 1990s psion released psion series 3 pda small mobile computing device supported user-written applications running operating system called epoc later versions epoc became symbian operating system used mobile phones ericsson motorola nokia 1996 palm computing released pilot 1000 pilot 5000 running palm os microsoft windows ce base pocketpc 2000 renamed windows mobile 2003 peak 2007 common operating system smartphones u.s 2007 apple introduced iphone operating system ios like mac os x based unix-like darwin addition underpinnings also introduces powerful innovative graphic user interface – later also used tablet computer ipad year later android introduced based modified linux kernel graphical user interface microsoft re-entered market windows phone 2010 due replaced windows 10 mobile 2015 addition wide range mobile operating systems contending area operating systems originally ran directly hardware provided services applications virtualization operating system runs control hypervisor instead direct control hardware mainframes ibm introduced notion virtual machine 1968 cp/cms ibm system/360 model 67 extended later 1972 virtual machine facility/370 vm/370 system/370 x86-based personal computers vmware popularized technology 1999 product vmware workstation 2001 vmware gsx server vmware esx server products later wide range products others including xen kvm hyper-v meant 2010 reported 80 percent enterprises virtualization program project place 25 percent server workloads would virtual machine time line virtual machines monitors operating systems blurred many ways virtual machine software today plays role formerly held operating system including managing hardware resources processor memory i/o devices applying scheduling policies allowing system administrators manage system
Operating systems
gecos field gecos field gecos field entry /etc/passwd file unix similar operating systems typically used record general information account user real name phone number typical format gecos field comma-delimited list order unix systems non-root users change information using chfn chsh command early unix systems bell labs used gecos machines print spooling various services field added carry information user gecos identity internet relay chat irc real name field commonly referred gecos field irc clients required supply field connecting hexchat x-chat fork defaults 'realname talksoup.app gnustep defaults 'john doe irssi reads operating system user full name replacing 'unknown defined irc clients use field advertising example znc defaulted got znc changed realname match configuration syntax 2015
Operating systems
binary synchronous communications binary synchronous communication bsc bisync ibm character-oriented half-duplex link protocol announced 1967 introduction system/360 replaced synchronous transmit-receive str protocol used second generation computers intent common link management rules could used three different character encodings messages six-bit transcode looked backwards older systems usascii 128 characters ebcdic 256 characters looked forward transcode disappeared quickly ebcdic usascii dialects bisync continued use one time bisync widely used communications protocol still limited use 2013 bisync differs protocols succeeded complexity message framing later protocols use single framing scheme messages sent protocol hdlc digital data communications message protocol ddcmp point-to-point protocol ppp etc different framing schemes one frame format exists within specific protocol bisync five different framing formats ack0 ack1 even/odd affirmative acknowledgement encoded two characters—dle '70 x dle ebcdic dle 0 dle 1 usasii dle dle transcode wabt wait transmit encoded dle dle dle w. frame formats begin least two syn bytes binary form syn byte property rotation byte equal original allows receiver find beginning frame searching received bit stream syn pattern found tentative byte synchronization achieved next character also syn character synchronization achieved receiver searches character start frame characters outside set described leading graphics sometimes used identify sender frame long messages syn bytes inserted approximately every second maintain synchronization ignored receiver normal block ending character etb etx followed check sum block check character bcc usascii one character longitudinal redundancy check lrc transcode ebcdic check sum two character cyclic redundancy check crc data frame may contain intermediate check sum preceded itb character ability include intermediate check sums long data frame allows considerable improvement error detection probability usascii characters also transmitted using odd parity additional checking pad characters required following line turn-around—nak eot enq ack0 ack1 transmission ends eot etx pad follows bcc pad either 1 bits alternating 0 1 bits next transmission begins pad character either syn optional heading containing control information precede data frame content heading defined protocol defined specific device heading present preceded soh start heading character followed stx start text text data normally follows heading begun stx terminated etx end text etb end transmission block normal data frames allow certain characters appear data block ending characters etb etx enq itb syn characters number unique characters transmitted therefore limited 59 transcode 123 usascii 251 ebcdic transparent data framing provides unrestricted alphabet 64 128 256 characters transparent mode block framing characters etb etx syn preceded dle character indicate control significance dle character represented sequence dle dle technique became known character stuffing analogy bit stuffing link control protocol similar str designers attempted protect simple transmission errors protocol requires every message acknowledged ack0/ack1 negatively acknowledged nak transmission small packets high transmission overhead protocol recover corrupted data frame lost data frame lost acknowledgment error recovery retransmission corrupted frame since bisync data packets serial-numbered considered possible data frame go missing without receiver realizing therefore alternating ack0s ack1s deployed transmitter receives wrong ack assume data packet ack went missing potential flaw corruption ack0 ack1 could result duplication data frame error protection ack0 ack1 weak hamming distance two messages two bits protocol half-duplex 2-wire environment packets frames transmission strictly unidirectional necessitating 'turn-around even simplest purposes acknowledgments turn-around involves 2-wire environment causes noticeable round-trip delay reduces performance datasets support full-duplex operation full-duplex 4-wire used many circumstances improve performance eliminating turn-around time added expense 4-wire installation support typical full-duplex data packets transmitted along one wire pair acknowledgements returned along much bisync traffic point-to-point point-to-point lines optionally use contention determine master station case one device transmit enq bid control device reply ack0 accept bid prepare receive nak wabt refuse cases connection terminal multiple hosts possible via dial telephone network multi-drop part initial bisync protocol master station normally computer sequentially poll terminals attached via analog bridges communication line accomplished sending message consisting enq character addressed device turn selected station transmits message master reply eot indicate data transmit original purpose bisync batch communications system/360 mainframe another mainframe remote job entry rje terminal ibm 2780 ibm 3780 rje terminals support limited number data formats punched card images print line images terminal non-ibm hardware vendors mohawk data sciences used bisync purposes tape-to-tape transmission programmer easily emulate rje terminal device ibm offered assembler language macros provide programming support system/360 era access methods btam basic telecommunications access method qtam queued telecommunications access method – later replaced telecommunications access method tcam ibm introduced vtam virtual telecommunications access method system/370 teleprocessing monitors ibm cics third-party software remote ducs display unit control system westi platforms used bisync line control communicate remote devices academic computing network bitnet together connecting networks geographic areas used bisync connect 3000 computer systems peak financial network s.w.i.f.t used bsc protocol communication regional center institution bank server leased line mid-1990 bsc replaced x.25 infrastructure important systems use bisync data framing different link control protocol houston automated spooling program hasp uses bisync half-duplex hardware conjunction link control protocol provide full-duplex multi-datastream communication small computer mainframe running hasp bisync terms conversational mode early x.25 networks tolerated connection scheme transparent bisync data frames encapsulated hdlc lapb data control packets several vendors encapsulate bisync transmissions within tcp/ip data streams bisync began displaced 1970s systems network architecture sna allows construction network multiple hosts multiple programs using telecommunications x.25 internet protocol later protocols like sna provide mere link control large number devices use bisync protocol
Internet protocols
apache systemml apache systemml flexible machine learning system automatically scales spark hadoop clusters systemml's distinguishing characteristics systemml created 2010 researchers ibm almaden research center led ibm fellow shivakumar vaithyanathan observed data scientists would write machine learning algorithms languages r python small data came time scale big data systems programmer would needed scale algorithm language scala process typically involved days weeks per iteration errors would occur translating algorithms operate big data systemml seeks simplify process primary goal systemml automatically scale algorithm written r-like python-like language operate big data generating answer without error-prone multi-iterative translation approach june 15 2015 spark summit san francisco beth smith general manager ibm analytics announced ibm open-sourcing systemml part ibm major commitment apache spark spark-related projects systemml became publicly available github august 27 2015 became apache incubator project november 2 2015 may 17 2017 apache software foundation board approved graduation apache systemml apache top level project
Distributed computing architecture
o-code o-code intermediate language emitted bcpl compiler compiled machine code computer intended run program method compiling allowed original bcpl compiler ported new machines easily result became widespread idea since used many recent compilers however interpret equivalent o-code virtual machine rather compiling originally case o-code machine virtual machine developed martin richards late 1960s give machine independence bcpl low-level forerunner c c++ concept behind o-code machine create o-code output stands object bcpl compiler o-code either interpreted normally compiled machine specific code idea used later compilers p-code pascal compilers bytecode generated jvm java compilers o-code allowed richards separate general compilation issues machine specific implementation issues writing bcpl compiler use bcpl compiler made compiler easy port result bcpl quickly became available many machines
Programming language topics
sagan software sagan open source gnu/gplv2 multi-threaded high performance real-time log analysis correlation engine developed quadrant information security runs unix operating systems written c uses multi-threaded architecture deliver high performance log event analysis sagan structure rules work similarly sourcefire snort ids/ips engine allows sagan compatible snort rule management software give sagan ability correlate snort ids/ips data sagan record events snort unified2 output format makes sagan compatible user interfaces snorby sguil base proprietary consoles sagan supports different output formats reporting analysis log normalization script execution event detection automatic firewall support via snortsam geoip detection/alerting multi-line log support time sensitive alerting
Computer security
protein structure evaluation suite amp server protein structure evaluation suite server prosess freely available web server protein structure validation designed university alberta assist process evaluating validating protein structures solved nmr spectroscopy structure validation particularly important component structure determination pipeline many protein structures small structural errors i.e distorted bond lengths angles incompatible torsion angles overlapping atoms easily detected visual inspection protein structures solved nmr spectroscopy large numbers structures generated coordinate inaccuracies common problem particularly acute nmr-based structure validation protocols primarily use noe nuclear overhauser enhancement j-coupling residual dipolar coupling rdc data assess validate structures particular try assess agreement experimentally observed calculated noes rdcs and/or j-couplings good agreement calculated observed parameters normally indicates good structure methods structure validation procheck molprobity resprox vadar focus measuring coordinate data rather experimental data assess quality bond torsion angle geometry prosess unique among structure validation servers evaluates coordinate quality experimental data quality prosess also able use nmr chemical shifts well noes assess validate protein structures chemical shifts easily precisely measurable nmr observables provide great deal information protein structure dynamics see protein chemical shift prediction specifically prosess assesses agreement observed chemical shifts shiftx-predicted ha ca cb n c hn nmr chemical shifts addition ability validate structures using chemical shifts prosess also checks many protein structure parameters including covalent bond quality non-covalent bond atomic packing quality torsion angle quality noe quality i.e measuring model agreement noe-based distance restraints total 8 different programs see prosess sub-programs used prosess evaluation validation process prosess handle single-chain x-ray models multi-chain x-ray models single-chain nmr ensembles multi-chain nmr ensembles monomeric multimeric proteins addition able validate nmr protein structures prosess used validate evaluate protein model regardless solved x-ray nmr comparative modelling etc. prosess generates detailed colorful structure validation report including tables color-coded images graphs bar charts many tables contain embedded hyperlinks additional details explanations graphs charts prosess uses simple rag red amber green color scheme indicate quality different structure parameters protein whole different members structure ensemble specific residues specific atoms different shades red indicate serious problems different shades yellow amber indicate potential problems different shades green indicate protein model residues/atoms free problems color also assigned number ranging 0 9with 0 bad 9 excellent structure quality assessment quantifiable prosess quality indices quality color scales designed specifically help non-structural biologists easily rapidly understand protein structure validation reports
Web technology
operand mathematics operand object mathematical operation i.e. object quantity operated following arithmetic expression shows example operators operands example '+ symbol operation called addition operand 3 one inputs quantities followed addition operator operand 6 input necessary operation result operation 9 number 9 also called sum augend 3 addend 6 operand also referred one inputs quantities operation operands may complex may consist expressions also made operators operands expression 3 5 first operand multiplication operator 2 second operand 3 5 expression contains addition operator operands 3 5 rules precedence affect values form operands operators expression multiplication operator higher precedence addition operator multiplication operator operands 5 2 addition operator operands 3 5 × 2 depending mathematical notation used position operator relation operand may vary everyday usage infix notation common however notations also exist prefix postfix notations alternate notations common within computer science comparison three different notations — represent addition numbers 1 2' mathematical expression order operation carried left right start leftmost value seek first operation carried accordance order specified i.e. start parentheses end addition/subtraction group example expression first operation acted upon expressions found inside parenthesis beginning left moving right find first case parenthesis 2 2 within parenthesis found expression 2 reader required find value 2 going value 2 4 found value remaining expression looks like next step calculate value expression inside parenthesis 2 4 6 expression looks like calculated parenthetical part expression start beginning left value move right next order operation according rules exponents start left value 4 scan eyes right search first exponent come across first expression come across expressed exponent 2 find value 2 4 left expression next order operation multiplication 4 × 4 16 expression looks like next order operation according rules division however division operator sign ÷ expression 16 − 6 move next order operation i.e. addition subtraction precedence done left right correct value original expression 4 × 2 − 2 2 10 important carry order operation accordance rules set convention reader evaluates expression follow correct order operation reader come forth different value different value incorrect value order operation followed reader arrive correct value expression operation carried proper order number operands operator called arity based arity operators classified nullary operands unary 1 operand binary 2 operands ternary 3 operands etc computer programming languages definitions operator operand almost mathematics computing operand part computer instruction specifies data manipulated operated time representing data computer instruction describes operation add multiply x operand operands one specify x operate well value x. additionally assembly language operand value argument instruction named mnemonic operates operand may processor register memory address literal constant label simple example x86 architecture mov ds ax value register operand codice_1 moved codice_2 register codice_3 depending instruction may zero one two operands
Computer architecture
miredo miredo teredo tunneling client designed allow full ipv6 connectivity computer systems ipv4-based internet direct native connection ipv6 network miredo included many linux bsd distributions also available recent versions mac os x discontinued includes working implementations released terms gnu general public license miredo free software
Computer security
activecampaign activecampaign email marketing marketing automation sales automation crm software platform small-to-mid-sized businesses based chicago illinois activecampaign founded jason vandeboom 2003 started consulting firm on-premise software provider helping small midsize businesses automate marketing tasks manage contacts 2013 company transitioned on-premise software software service business focused marketing sales automation 2018 activecampaign 60,000 clients 60 million recurring revenue 2016 activecampaign raised 20 million silversmith capital partners activecampaign headquartered chicago offices indianapolis sydney australia activecampaign provides cloud-based marketing sales automation software features email marketing lead scoring web analytics crm platform live chat messaging platform called conversations software uses customer data create customized messaging according pc magazine activecampaign offers lot features relatively low price downside confusing use times thankfully help resources plentiful solutions review pointed users access detailed behavior tracking capabilities well precision marketing options segmentation 2018 activecampaign appeared crain chicago business best places work list inc.com list best workplaces chicago tribune list top midsize workplaces
Distributed computing architecture
hackers.mu hackers.mu group developers mauritius focused computer security ietf standards linux open source software adoption worked implementing tls 1.3 linux open source software ietf 100 hackathon part tls working group also prepared high school students google code-in 2016 marked first time mauritius participated 2017 trained another batch high school students would lead first grand prize winner mauritius ietf 101 hackers.mu acted tls 1.3 champions continued work application integration support june 2018 hackers.mu organized hackathon codename operation jask fix sigspoof3 number open source projects july 2018 hackers.mu participated ietf 102 hackathon tls 1.3 champions work inter-operability applications support http 451 additionally active authoring ietf standards rfc 8270
Computer security
revolution os revolution os 2001 documentary film traces twenty-year history gnu linux open source free software movement directed j. t. s. moore film features interviews prominent hackers entrepreneurs including richard stallman michael tiemann linus torvalds larry augustin eric s. raymond bruce perens frank hecker brian behlendorf film begins glimpses raymond linux ipo torvalds idea open source perens stallman sets historical stage early days hackers computer hobbyists code shared freely discusses change came 1978 microsoft co-founder bill gates open letter hobbyists pointedly prodded hobbyists pay stallman relates struggles proprietary software vendors mit artificial intelligence lab leading departure focus development free software gnu project torvalds describes development linux kernel gnu/linux naming controversy linux evolution commercialization raymond stallman clarify philosophy free software versus communism capitalism well development stages linux michael tiemann discusses meeting stallman 1987 getting early version stallman gcc founding cygnus solutions larry augustin describes combining gnu software normal pc create unix-like workstation one third price twice power sun workstation relates early dealings venture capitalists eventual capitalization commodification linux company va linux ipo brian behlendorf one original developers apache http server explains started exchange patches ncsa web server daemon developers led release patchy webserver dubbed apache frank hecker netscape discusses events leading netscape executives releasing source code netscape browser one signal events made open source force reckoned business executives mainstream media public large point validated film release netscape source code eventually became firefox web browser reclaiming large percentage market share microsoft internet explorer film also documents scope first full-scale linuxworld summit conference appearances linus torvalds larry augustin keynote stage much footage film shot silicon valley film appeared several film festivals including south southwest atlanta film video festival boston film festival denver international film festival best documentary savannah film video festival kudzu film festival every review noted historical significance information noticed found production values high presentation history mainly dry even resembling lecture ron wells film threat found film important worthwhile well thought explaining principles free software open source concepts noting failure represent camera debate representatives proprietary software camp wells gave film 4 5 stars tv guide rated film 3 4 stars surprisingly exciting fascinating sharp looking good soundtrack daily variety saw film targeted equally techno-illiterate savvy-hacker crowd educating patting one group head canonizing strong enough enjoyable recommendation negative side new york times faulted film one-sidedness found reliance jargon fairly dense going gave recommendation internet reviews found didactic dull documentary glorifying software anarchy raging microsoft sun lacking follow-through red hat valinux stock 2007 2 peak value lots talking heads toxicuniverse.com noted revolution os blatantly serves infomercial propaganda bearded throwback sixties hacker richard stallman serves movement spiritual leader scandinavian linus torvalds acts mild mannered chief engineer developer linux kernel tim lord reviewing slashdot film interesting worthy viewing misgivings growth free software movement eventual co-option open source movement supposed linux battle microsoft movie quickly hijacked participants film lacks staple documentaries scenes multiple people later analyzed individually participants indeed much back-and-forth linux benefits notably missing w e never shown anyone using linux except unhappy users installfest debate linux vs windows missing showing origin os response proprietary expensive sun dec software hardware growth solely due apache web server lord notes film shows challenge torvalds stallman equally disingenuous remarks linux vs gnu/linux naming issue
Operating systems
disinfectant software disinfectant popular antivirus software program classic mac os originally released freeware john norstad spring 1989 disinfectant featured system extension would detect virus infections application users could scan remove viruses new versions disinfectant subsequently released detect additional viruses bob levitus praised recommended disinfectant 1992 may 1998 norstad retired disinfectant citing new danger posed macro viruses disinfectant detect inability single individual maintain program caught
Computer security
fuse mediation router fuse mediation router open source tool integrating services using enterprise integration patterns based apache camel use enterprise organizations certified productized fully supported people wrote code fuse mediation router uses standard method notation go diagram implementation without coding fuse mediation router rule-based routing process mediation engine combines ease basic pojo development clarity standard enterprise integration patterns deployed inside container used stand-alone works directly kind transport messaging model rapidly integrate existing services applications fuse mediation router part red hat jboss fuse fusesource offers graphical eclipse-based tooling apache camel download
Web technology
high-water mark computer security high-water mark access control introduced clark weissmann 1969 pre-dates bell–lapadula security model whose first volume appeared 1972 high-water mark object less user security level opened object relabeled reflect highest security level currently open hence name practical effect high-water mark gradual movement objects towards highest security level system user writing confidential document checks unclassified dictionary dictionary becomes confidential user b writing secret report checks spelling word dictionary becomes secret finally user c assigned assemble daily intelligence briefing top secret level reference dictionary makes dictionary top secret low-water mark extension biba model biba model no-write-up no-read-down rules enforced model rules exactly opposite rules bell-la padula model low-water mark model read permitted subject label reading degraded object label classified floating label security models
Computer security
run run run run known super pierrot スーパーピエロ japan fourth final incarnation mr universal video game mascot returning mr. roots clown bouncing powerball hurl monsters mr. runs along playfield picking dots leaving line behind player encouraged create closed sections precariously balanced log traps rolled downslope crushing enemies resulting game somewhat cross mr congo bongo pac-man qix title reference song da doo ron ron goal run run rack points completing screens screen completed whenever fruits/dots eaten regular monsters alpha-monsters sidekicks defeated using rope follows mr. inscribe dots convert cherries familiar fruit mr. collect cherries worth points dots eating restores powerball quickly eating dots would time mr. inscribes fruit progress higher tier dots become cherries cherries become apples apples become lemons lemons become pineapples eating dot awards 10 points 1/16 powerball recharge eating pineapple worth 160 points 1/4 powerball recharge players additionally encouraged inscribe sections playfield letters e x r constant feature mr games randomly one inscribed fruits turn flashing letter spot corresponding movement alpha-monster top screen mr. runs spot monster sporting letter release top screen three blue henchmen resemble three ghost-like monsters original mr chase mr. defeating alpha-monster lock letter 5 letters earned player earns extra life well progressing next stage also earn 5,000 point bonus points also awarded defeating monsters directly firing powerball monster awards 500 points consumes powerball needs replenished eating fruit points earned powerball bounces surface bounce raises bonus 500 points maximum 3000 points earned smashing monsters rolling log earns 1000 points possible roll multiple monsters earn cumulative bonus 500 per extra monster 1500 2nd 2000 3rd etc. apparently 10,000 point bonus smashing 5 monsters like mr. games monsters nameless except alpha-monsters defy easy description two types monsters attempt foil clown efforts green clam-like monster blue snake-like monster neither particularly sophisticated although clam monsters seemingly clever moments bumble path way powerball blue snakes linger long direct path convert fireball charge across playing field state immune powerball common arcade games contact monsters instantly fatal mr. shown electrocuted complete visible flashing skeleton reappearing black skeleton time stage elapses music changes surviving monsters convert different form clam monsters become blue armored spines snake monsters essentially become different looking snake monsters speed monster willingness chase mr. major changes fairly easily eluded long player simply run away instead mr. climb terrain closely chased monsters lose lot time changing levels playfield whereas mr. gets slight speed going downslope short duration music resumes monsters transform back old selves pattern transformation repeating alpha-monsters summoned letter circle released three henchmen henchmen home mr. typically precede alpha-monster killing alpha-monster rids playfield henchmen although easier lure four path log smash alpha-monsters also released every time score reaches increments 5,000 points unless already alpha-monster playfield configured rom occur infrequently bonus diamond worth 10,000 points show manner letter circles fruit inscribed player collects stage ends awarded bonus credit fashion original mr versions released msx 1987 amiga atari st 1990 ports amstrad cpc commodore 64 zx spectrum cancelled development
Computer architecture
alec muffett alec david edward muffett born april 22 1968 anglo-american internet-security evangelist architect software engineer principally known work crack original unix password cracker cracklib password-integrity testing library also active open-source software community muffett joined sun microsystems 1992 working initially systems administrator rose “ ranks ” become principal engineer security position held retrenched many others 2009 shortly oracle acquired sun sun one researchers worked factorization 512 bit rsa challenge number rsa-155 successfully factorized august 1999 muffett also worked sun md5 hash algorithm introduced solaris 9 update 2 new algorithm drew muffett work pluggable crypt implemented many different languages example python algorithm uses complete text famous soliloquy shakespeare hamlet question ... constant data muffett justified choice text exposes programmers shakespeare got good thing sabbatical year muffett began work mine project lead developer subsequently became director consultant green lane security also consults surevine became director open rights group october 2011 muffett blogs professionally computer world unscrewing security personally dropsafe numerous publications credit besides frequent presenter technical conferences muffett co-inventor darren moffat casper dik patent method apparatus implementing pluggable password obscuring mechanism united states patent 7,249,260 issued june 12 2003 2015 muffett named one top 6 influential security thinkers sc magazine october year coauthored rfc 7686 .onion special-use domain name jacob applebaum recently muffett assisted new york times creation tor onion site following created onion wikipedia site accessible tor previously muffett worked software engineer facebook leading team added end-to-end encryption facebook messenger currently works principal engineer infrastructure security deliveroo
Computer security