text
stringlengths 6
1.88M
| source
stringclasses 13
values |
|---|---|
scroll lock scroll lock ⤓ ⇳ lock key typically associated status light ibm-compatible computer keyboards depending operating system may used different purposes applications may assign functions key change behaviour depending toggling state key frequently used therefore reduced specialized keyboards lack altogether pressing performs function pressing behavior remnant original ibm pc keyboards dedicated key instead assigned pause function break function key meant lock scrolling techniques vestige original ibm pc keyboard original design intended modify behavior arrow keys mode arrow keys would scroll contents text window instead moving cursor usage toggling lock key like num lock caps lock state persists key released today particular use rare modern programs honoring behavior include ibm lotus notes forté agent image-line fl studio renoise microsoft excel microsoft project libreoffice calc occasions microsoft word text editors notepad++ microsoft visual studio exhibit similar behavior arrow keys used pressed gui environments neglect means scrolling must accomplished mouse using means scrollbars scroll wheels often middle wheel mouse button works toggle determining mouse movements move mouse cursor scroll contents scroll window web browsers including firefox internet explorer support caret browsing mode toggled window scrolling behaviour caret navigation disabled default similar suggested scroll lock enabling caret navigation enable cursor scrolling behaviour scroll lock disabled pressing key linux console text scrolling screen freezes console output input text sent screen program continues running usual pressed screen unfrozen text generated freeze displayed allows user pause display read long messages scroll screen quickly read example system booting provided keyboard driver already loaded configured otherwise used instead scroll lock terminal linux freeze unfreeze terminal output respectively behaviour emulates hold screen key similar flow control mechanisms computer terminals behaviour must distinguished pressing pause key post dos default effect temporarily halting running process freebsd system console key additionally enables scrolling pressing scroll lock one use scroll pressing scroll lock disables mode moves back bottom output linux console implements behaviour using requiring active multiuser dos system manager real/32 activating boot always enter special diagnostic mode operating system loaded device drivers display detailed status debugging information interaction operating system sometimes several screenfuls per loaded driver automatic scrolling suspended long remains activated dr-dos 7.02 higher provides config.sys directive named codice_1 change scroll lock status fly activating boot enter diag mode well wherein special drivers may display verbose messages contrast situation multiuser dos family normal dos drivers typically display additional information operating system however temporarily suspend automatic timeouts codice_2 config.sys trace codice_3 single-stepping modes long active microsoft windows nt family starting windows 2000 debugging feature enabled allows user manually crash system generating memory dump analysis current state operating system accomplished setting reg_dword registry key hkey_local_machine\system\currentcontrolset\services\i8042prt\parameters\crashonctrlscroll 1 set user hold key tap key twice trigger blue screen death microsoft visual basic 5.0 6.0 pauses running program integrated development environment alias conjunction alternative dos keyboard console drivers freekeyb k3plus also served part copy paste facility applications compared standard keyboard driver keyb drivers offered number extensions including extended keystroke buffer key stacking facility macro recorder second cursor called copycursor could invoked demand default pressing middle mouse button freely moved screen using cursor keys mouse even outside area reachable standard cursor running application invoked pressing left mouse button characters copycursor could stuffed one another keyboard buffer would read running application emulated key alt numpad input thereby typically showing location standard cursor copycursor would move next screen position backwards normal keyboard input still possible copycursor enabled user could switch two cursors toggling hotkey pressing would exit copycursor next invocation would show position standard cursor rather previous location screen contents scrolled position copycursor would move accordingly reaching display limits activated keypresses would still reach normal keystroke buffer copycursor input would stacked internally later use second queue dynamically maintained within extended keystroke buffer thereby possible collect selected screen output different programs spool data much later within yet another application toggling also possible use input macro recorder later use scrap macro since integral part keyboard drivers fully transparent running software therefore worked virtually dos programs including command prompt temporary shelled programs task switchers ibm pc documentation called inactive key pc magazine asked executive keyboard manufacturer key tronic key purpose 1983 interview replied n't know put indicator light sometimes used purposes keyboard layout indicator linux distributions applications less likely cause problems manipulating keys/lights keyboard video mouse switches kvm often use scroll lock key keyboard connected kvm switch selecting computers kvm switches on-screen display osd double click scroll lock key often brings osd allowing user select desired computer list access configuration menu kvm models especially lack osd switch input corresponding number key pressed scroll lock case 2-port switches arrow keys simple models two four inputs may immediately switch next input following double press scroll lock key laptops keyboards physical key second function another key acts key pressed common methods another way press key use onscreen keyboard windows 8 found control panel ease access center selecting start on-screen keyboard provide access emulation standard 101/102-key keyboard windows 10 function performed on-screen keyboard module codice_4 started either command line alternatively run menu
|
Computer architecture
|
yunohost yunohost debian gnu/linux based distribution packaged free software automates installation personal web server purpose yunohost allow users easily host web services enabling simple point-and-click web interface installing various web apps currently supported apps include email server webmail interface wordpress website instant messaging server news aggregator file sharing server seedbox among others name yunohost play words internet meme u yunohost development began march 2012 still actively maintained version 1.0 based debian squeeze released august 5 2012 version 2.0 based debian wheezy released version 2.4 based debian jessie released version 3.0 based debian stretch released version 2.2 released compatible debian wheezy jessie bind replaced dnsmasq mailbox quota system set yunohost 2.4 released includes backup recovery system system fine management service configuration improvements application management packaging many new features bug fixes mysql replaced mariadb theanti-spam amavis replaced rspamd release compatible debian jessie yunohost 3.0 released june 17 2018 includes new features compatible new version debian released almost year ago debian stretch also marks end cycle debian jessie adds new security features program nginx ssh ... also updates metronome rspamd recent versions improvements translation made finally backup/restore system also switches stable version occitan language available released july 5 2019 brings new unified list applications 18 march 2019 time4vps started offer vps servers yunohost template
|
Computer architecture
|
scanner access easy scanner access easy sane application programming interface api provides standardized access raster image scanner hardware flatbed scanner handheld scanner video- still-cameras frame grabbers etc. sane api public domain discussion development open everybody commonly used linux sane differs twain cleanly separated front ends user programs back ends scanner drivers whereas twain driver handles user interface well communications scanner hardware sane driver provides interface hardware describes number options drive scan options specify parameters resolution scan scan area colour model etc option name information type units range possible values e.g. enumerated list convention several well known options front ends supply using convenient gui interaction e.g. scan area options set dragging rectangular outline preview image options presented using gui elements appropriate type e.g. sliders drop-down lists etc one consequence separation network scanning easily implemented special handling either front ends back ends host scanner saned daemon runs handles network requests client machines net back end driver connects remote host fetch scanner options perform previews scans saned daemon acts front end locally simply passes requests data network connections local scanner similarly net back end passes requests data local front end remote host various types unsupervised batch scanning also possible minimum support needed back end driver many scanners support attachment document feeders allow large number sheets paper automatically scanned succession using sane api front end simply play back set options scan driving document feed scans load next sheet paper front end obtain set options user several user interfaces written combine sane easy user method controlling xsane graphical front end sane written oliver rauch available microsoft windows linux unix os/2 licensed gnu general public license gpl windows version allows windows computer access scanner attached unix os/2 mac os x network computer generally local windows computer complete sane-back-ends versions possibly work scanner models connected locally simple scan simplified gui using sane intended easier use better integrate gnome desktop xsane initially written ubuntu maintained robert ancell canonical ltd. linux simple scan first fielded part ubuntu 10.04 lucid lynx also used lubuntu xubuntu gscan2pdf interface scanning documents pdf gnome desktop uses sane communicate scanner available gpl includes common editing tools e.g. rotating cropping pages also able perform ocr using several optional ocr tools save searchable pdf pdf files downsampled upon saving swingsane cross-platform java front end sane written maintained roland quast available microsoft windows linux mac os x licensed apache 2.0 license source code project also adapted use existing swing application
|
Operating systems
|
orchidée orchidée software developed ircam computer-aided orchestration tool matlab-based application communicates traditional computer-aided composition environments open sound control messages means effectively controlled programs like max/msp openmusic developed grégoire carpentier damien tardieu phds ircam help supervision composer yan maresz recent example use orchestral composition jonathan harvey speakings premiered 2008 speech analyzed computed provide orchestral combinations composer given input target sound orchidée creates musical score imitates sound using mixture traditional instruments searches within large instrument sample database combinations sounds perceptually match target application takes account complex combinatorial possibilities considering virtually infinite sets different sounds created orchestra also considers musical attributes instruments dynamics perceptual attributes brightness roughness example speakings mantra oh/ah/hum analyzed imputed orchidée turn generated different possibilities orchestration mantra developed throughout piece using possibilities musical works using orchidée
|
Programming language topics
|
list default file systems default file system used various operating systems
|
Computer file systems
|
webscalesql webscalesql open-source relational database management system rdbms created software branch production-ready community releases mysql joining efforts companies incorporating various changes new features mysql webscalesql aimed toward fulfilling various needs arising deployment mysql large-scale environments involve large amounts data numerous database servers source code webscalesql hosted github licensed terms version 2 gnu general public license project website announced december 2016 companies involved would longer contribute project running mysql numerous servers large amounts data scale terabytes petabytes data creates set difficulties many cases arise need implementing specific customized mysql features need introducing functional changes mysql companies faced similar set difficulties production environments used result availability multiple solutions similar challenges webscalesql announced march 27 2014 joint effort facebook google linkedin twitter alibaba group joining january 2015 aiming provide centralized development structure extending mysql new features specific large-scale deployments building large replicated databases running server farms result webscalesql attempted open path toward deduplicating efforts founding company putting maintaining branch mysql toward bringing together developers webscalesql created branch mysql latest production-ready community release version 5.6 project aimed tightly follow new mysql community releases branching path selected instead becoming software fork mysql selection mysql production-ready community releases webscalesql upstream instead selecting available mysql forks mariadb percona server result consensus four founding companies concluded features already existing mysql 5.6 suitable large-scale deployments additional features kind planned mysql 5.7 initial changes feature additions webscalesql introduced mysql 5.6 codebase came engineers employed four founding companies however project open peer-reviewed community contributions available new features changes included following planned new features changes included following webscalesql distributed source-code-only form official binaries available compiling source code running webscalesql supported x86-64 linux hosts requiring time toolchain supports c99 c++11 language standards source code hosted github available version 2 gnu general public license gpl v2 december 2016 webscalesql website announced companies originally involved collaborating project facebook google linkedin twitter alibaba would longer contribute project announcement blamed differences among needs various companies end collaboration
|
Databases
|
list input methods unix platforms intended non-exhaustive list input methods unix platforms input method means entering characters glyphs corresponding encoding character set see input method page information
|
Operating systems
|
socket am1 socket fs1b branded socket am1 socket designed amd launched april 2014 desktop socs value segment socket am1 intended class cpus contain integrated gpu chipset essentially forming complete soc implementation pins display pci express sata i/o interfaces directly socket amd first compatible cpus designated apus 4 socketable chips kabini family jaguar microarchitecture marketed athlon sempron names announced april 9 2014 brand names athlon sempron underlying microarchitectures jaguar puma products socs means chipset die apu motherboard amd mobile cpus available one 722-pin package socket fs1 sure whether notebook cpus compatible socket am1 vice versa mobile counterpart socket ft3 bga-769 least one board supported coreboot
|
Computer architecture
|
erroneous program design programming languages erroneous program one whose semantics well-defined language implementation obligated signal error either compile execution time example ada defining condition erroneous means language implementation need perform potentially expensive check e.g global variable refers object subroutine parameter may nonetheless depend condition true defining semantics program
|
Programming language topics
|
open web analytics open web analytics owa open-source web analytics software created peter adams owa written php uses mysql database makes compatible running amp solution stack various web servers owa comparable google analytics though owa server software anyone install run host google analytics software service offered google owa supports tracking wordpress mediawiki two popular web site frameworks application helps keep track observe influx views website program also tracks competitors company growth compared
|
Web technology
|
cost-based anti-spam systems since spam occurs primarily cheap send proposed set solutions require senders pay cost order send spam making prohibitively expensive spammers gatekeeper would sell electronic stamps keep proceeds micropayment electronic money would paid sender recipient isp gatekeeper proof-of-work systems hashcash penny black require sender pay computational cost performing calculation receiver later verify verification must much faster performing calculation computation slows sender significantly impact receiver point slow machines send spam—often millions millions every user wants send email moderate number recipients suffers seconds delay sending millions emails would take unaffordable amount time approach suffers sender maintains computation farm zombies refinement stamp systems method requiring micropayment made form penalty imposed recipient considers email abusive addresses principal objection stamp systems popular free legitimate mailing list hosts would unable continue provide services pay postage every message sent 2004 bill gates announced microsoft working solution requiring so-called “ unknown senders ” i.e senders accepted list recipient post “ electronic equivalent ” stamp whose value would lost sender recipient disapproves email gates said microsoft favors solutions short-term would rely contingent payment solution solve spam problem longer run microsoft aol well yahoo recently introduced systems allow commercial senders avoid filters obtain paid pre-paid certificate certification lost sender recipients complain approach suffers user initially signs legitimate mailing list later decides want receive e-mail lazy users simply click spam button e-mail client rather going formal unsubscription process detailed bottom message end-user gets effect either way without realizing consequences list host may face however companies implementing penalty approach certifying withdrawing certification commercial senders learned account problem setting appropriate complaint thresholds intent sender-at-risk solutions impose significant cost sender recipient rejects message subsequent receiving email deter spam making economically prohibitive send unwanted email messages allowing legitimate emailers send messages little expense anti-spam activist daniel balsam attempts make spamming less profitable bringing lawsuits spammers approach financially sustainable activist questionable whether actually reduces spam either activist anyone else
|
Computer security
|
venom security vulnerability venom virtualized environment neglected operations manipulation computer security flaw publicly disclosed 2015 jason geffner crowdstrike flaw introduced 2004 affected versions qemu xen kvm virtualbox date patched following disclosure existence vulnerability due flaw qemu virtual floppy disk controller venom registered common vulnerabilities exposures database cve-2015-3456
|
Computer security
|
ctera networks ctera networks privately held enterprise software company headquartered new york israel company regional offices uk italy france spain germany australia ctera partnered companies including amazon web services hewlett packard enterprise ibm clients include deutsche telekom banco santander axa united states department defense october 2016 ibm became ctera reseller ibm cloud object storage integrated ctera enterprise file services platform deployed on-premises softlayer cloud hybrid on-premises/cloud setup ctera mentioned gartner 2016 magic quadrant data center backup recovery software ctera founded 2008 liran eshel zohar kaufman company raised 9 million series funding round january 2009 led benchmark capital march 2012 ctera raised 11 million funding round lead venrock included strategic investment cisco systems participation prior investor benchmark capital raised approximately 15 million july 2014 ctera raised 25 million series c funding round led bessemer venture partners participation benchmark capital cisco venrock september 2016 ctera announced additional 25 million funding round led bessemer venture partners participation cisco new investor vintage investment partners investment considered part earlier series c funding round consisted 25 million july 2014 2016 ctera raised 70 million funding gartner named ctera one five cool venders storage technologies 2013 gartner included ctera 2015 critical capabilities enterprise endpoint backup magic quadrant enterprise file synchronization sharing efss ctera included deloitte fast 500 list technology 2015 ctera mentioned gartner 2016 magic quadrant data center backup recovery software june 2016 ctera earned contract provide private cloud file sharing solution united states department defense part agreement ctera disa defense information systems agency co-developed mutual authentication technology using government-issued smart cards additional layers protection beyond standard enterprise integration microsoft active directory servers 2009 ctera released first cloud storage gateway c200 gateway combined speed local network storage off-site cloud storage backup technology 2010 ctera released c400 cloud storage gateway added features office server backup recovery collaboration capability multiple users working files stored cloud gateway 2011 c800 gateway released 24 tb raw local storage 2016 ctera announced virtual cloud storage gateway deployed vmware kvm servers enabled customers use existing hardware ctera released updates cloud storage gateway portfolio april 2016 focused efficiency storage capacity ctera released enterprise file sync share efss 2012 enabled users access share collaborate files location storing files either locally cloud also 2012 ctera launched mobile app made possible access files backups ios android devices december 2015 ctera announced cloud server data protection storage-as-a-service server data protection software enterprise cloudops cloud server data protection protects server data private virtual private cloud using backup agents windows linux environments object storage services cloud platforms amazon web services microsoft azure ibm cloud openstack-based clouds
|
Computer security
|
networked help desk networked help desk open standard initiative provide common api sharing customer support tickets separate instances issue tracking bug tracking customer relationship management crm project management systems improve customer service reduce vendor lock-in initiative created zendesk june 2011 collaboration eight founding member organizations including atlassian new relic otrs pivotal tracker servicenow sugarcrm first integration zendesk atlassian issue tracking product jira announced 2011 atlassian summit august 2011 34 member companies joined initiative year launching 50 organizations joined within zendesk instances feature branded ticket sharing support tools generally built around common paradigm begins customer making request incident report create ticket ticket progress status updated annotations attachments annotations attachments may visible customer public visible analysts private customers notified progress made ticket complete people necessary complete ticket using separate support tools additional overhead introduced maintaining relevant information ticket tool notifying customer progress made group completing ticket example customer support issue caused software bug reported help desk using one system fix documented developers another analyzed customer relationship management tool keeping records system up-to-date notifying customer manually using swivel chair approach unnecessarily time-consuming error-prone information transferred correctly customer may re-explain problem time ticket transferred systems networked help desk api implemented possible several different applications related customer support experience synchronize data one uniquely identified shared ticket many applications domains implemented apis allow data imported exported modified network help desk provides common standard customer support information automatically synchronize several systems implemented two systems quickly share tickets configuration change understand interface communication two instances specific ticket occurs three steps invitation agreement sharing ticket data continued synchronization tickets standard allows full delegation analysts systems make public private comments synchronize status well partial delegation instance receiving ticket make private comments status changes synchronized tickets may shared multiple instances harvey kandola countersoft suggested would preferable single application consolidates tracking related functions rather using multiple tools connecting dots initiatives like networked help desk
|
Distributed computing architecture
|
event driven executive event driven executive edx computer operating system originally developed ibm control research laboratory devices experiments included application programming language known edl hcf host communication facility ibm research division opened san jose research laboratory sjrl 1956 building 025 ibm plant site san jose california dr. henry m. gladney established first laboratory automation project 1968 ibm 1800 computer various instruments chemistry physics laboratories throughout sjrl linked 1800 control data acquisition processing note long time instrumentation came embedded chips microprocessors output sophisticated research instrument likely strip chart paper squiggly marks perhaps punched paper tape dr. gladney became manager research computing facility rcf research moved building 028 1970 established new department rcf laboratory automation group tasked transition new sensor-based computer ibm system/7 produced boca raton florida robert w. martin appointed first line manager group staff consisting ray aylsworth donald l. raimondi gerd hochweller post-doctoral fellow assignment germany system/7 much smaller machine 1800 intended co-located individual research labs along instruments would service multiple system/7s hosted large scale computing purposes ibm system/360 “ mainframe ” served sjrl whole system/7 somewhat unusual especially programmer perspective lack supporting software basic human input/output interface teletype keyboard printer along paper tape reader punch hard disc drive data storage along digital analog input/output process interrupt could used lab instrument interface data acquisition instrument control sort operating system high level programming facility basic assembler language program another way putting would say delivered user friendly users research scientists engineers i.e non-programming professionals clear start order provide successful system/7 based environment laboratory automation sjrl would necessary develop real-time sensor-based multitasking multiprogramming operating system associated application development facility provided appropriate high level application programming language requisite special features e.g sensor i/o also communication interface large scale host computer program development bidirectional data transfer data analysis result development operating system known laboratory automation basic supervisor system/7 labs/7 application development language labs/7 real-time multitasking multiprogramming operating system application development language needed provide timing process interrupt capability analog digital input output commands allow data acquisition control external laboratory instruments along basic computational functions direct access data storage host communications hierarchical environment addition programming language associated program preparation facility compiler also needed defined decided use syntactical model could processed system/360 macro assembler would obviate need writing compiler machine language instructions created interpret object code output assembler effect high level instruction set programming language hypothetical virtual real-time sensor-based computer labs/7 provided language interpreter implemented system/7 machine language mimicked today language emulated virtual machine another element labs/7 package general purpose utility programs today would probably called apps finally system/360 software package known host communication facility hcf developed provide bi-directional data transfer host system/360 multiple satellite system/7s together labs/7 provided environment 1 application program could written compiled host system/360 downloaded host system/7 scientist laboratory 3 invoked control laboratory apparatus/instrument/machine 4 acquire measurement results instrument 5 send data host computer 6 start program host analyze data 7 return display results analysis scientist laboratory course system/7 could operated completely standalone i.e non-hierarchical environment usage labs/7 increased sjrl ibm organizations trying implement applications system/7 became aware labs/7 tried found extremely useful among general product division ibm plant site san jose sjrl sister research labs yorktown ny zürich switzerland ibm federal systems division oswego ny ibm office products division lexington ky. word labs/7 spread “ field ” charged marketing system/7 ibm customers cooperative effort mounted involving program authors sjrl team ibm system engineers led fred schneider make software available customers installed user program iup iup thought “ ” software package available ibm without support warranties associated formal product software labs/7 iup relatively successful came rather late product lifetime system/7 1976 ibm announced ibm series/1 successor system/7 series/1 last line special purpose sensor-based computers produced ibm laboratory automation group sjrl acquired early model series/1 announcement time ported labs/7 series/1 labs/7 became edx/1 event driven executive course included embedded interpreter programming language appropriately named edl event driven language time ibm field support team expanded significant effort underway make software available ibm customers field developed program fdp fdp step ibm software hierarchy still caveat “ ” package minimal formal ibm support development powerful terminal control product known communications facility edx/cf sales edx especially focused distributed computing environment whereby series/1 used primarily terminal controller many cases attached system/370 host computer edx efficient system able support large number work stations installed base edx grew product support edx transferred ibm general systems division series/1 product division boca raton fl edx became fully supported ibm program product edx origin tool laboratory automation 1981 ibm announced series/1 edx-based application software package edx laboratory automation software developed sjrl iup product number 5798-rhb edx edl well accepted marketplace successful ibm software products application programs developed edl run edx e.g communication facility multiple terminal monitor u.s. marine corps recognized extensive usage series/1 edx 1984 edx edl ported ibm pc product known hummingbird ibm plant site san jose california implemented completely automated warehouse facility inventory system production parts complete robot fork lifts control one series/1 computer running edx system operation late 1999 one example major applications within ibm companies developed edx-based applications e.g utility packages developed legler recently september 2014 program announced business partners ibm datatrend allows running applications ported series/1 unix based systems 1980 martin raimondi received ibm corporate award work developing edx edl
|
Operating systems
|
access structure access structures used study security system multiple parties need work together obtain resource groups parties granted access called qualified set theoretic terms referred qualified sets turn set qualified sets called access structure system less formally description needs cooperate order access resource original use cryptography resource secret shared among participants subgroups participants contained access structure able join shares recompute secret generally resource also task group people complete together creating digital signature decrypting encrypted message reasonable assume access structures monotone sense subset access structure sets contain subset also form part access structure
|
Computer security
|
sip uri scheme sip uri scheme uniform resource identifier uri scheme session initiation protocol sip multimedia communications protocol sip address uri addresses specific telephone extension voice ip system number could private branch exchange e.164 telephone number dialled specific gateway scheme defined sip address written user domain.tld format similar fashion email address address like instructs sip client use naptr srv schemes look sip server associated dns name voip-provider.example.net connect server records found name associated ip address client directly contact sip server ip address port 5060 default using udp transport protocol ask server may gateway connected destination user 1-999-123-4567 gateway may require user register using sip placing call destination port provided part sip uri naptr/srv lookups used rather client directly connects specified host port sip address text much like e-mail address may contain non-numeric characters client may sip phone device numeric telephone-like keypad various schemes exist associate entirely numeric identifier publicly reachable sip address include inum initiative issues e.164-formatted numbers corresponding sip address number sip.inum.net sip broker-style services associate numeric *prefix sip domain name e164.org e164.arpa domain name servers convert numbers addresses one-by-one dns reverse-lookups sip addresses may used directly configuration files instance asterisk pbx installations specified web interface voice-over-ip gateway provider usually call forwarding destination address book entry systems allow speed dial user address book using vertical service code may allow short numeric code like *75xx translated pre-stored alphanumeric sip address theory owner sip-capable telephone handset could publish sip address could freely directly reached worldwide much way smtp e-mail recipients may contacted anywhere almost cost message sender anyone broadband connection could install softphone ekiga call sip addresses free practice various forms network abuse discouraging creation publication openly reachable sip addresses server logs looks like attempt call palestinian mobile telephone israel country code +972 randomly trying 9- common code outside line office pbx 011- overseas call prefix north american numbering plan 7- off-chance pbx using instead 9- outside line security tools firewalls fail2ban must therefore deployed prevent unauthorised outside call attempts many voip providers also disable overseas calls countries specifically requested enabled subscriber sips uri scheme adheres syntax sip uri differing scheme codice_1 rather codice_2 default internet port address sips 5061 unless explicitly specified uri sips allows resources specify reached securely mandates hop request forwarded target domain must secured tls last hop proxy target domain user agent secured according local policies sips protects attackers try listen signaling link provide real end-to-end security since encryption hop-by-hop every single intermediate proxy trusted
|
Internet protocols
|
streaming media streaming media multimedia constantly received presented end-user delivered provider verb stream refers process delivering obtaining media manner term refers delivery method medium rather medium alternative file downloading process end-user obtains entire file content watching listening client end-user use media player start playing digital video digital audio content entire file transmitted distinguishing delivery method media distributed applies specifically telecommunications networks delivery systems either inherently streaming e.g radio television streaming apps inherently non-streaming e.g books video cassettes audio cds example 1930s elevator music among earliest popular music available streaming media nowadays internet television common form streamed media term streaming media apply media video audio live closed captioning ticker tape real-time text considered streaming text live streaming delivery internet content real-time much live television broadcasts content airwaves via television signal live internet streaming requires form source media e.g video camera audio interface screen capture software encoder digitize content media publisher content delivery network distribute deliver content live streaming need recorded origination point although frequently challenges streaming content internet user enough bandwidth internet connection may experience stops lags slow buffering content users may able stream certain content due compatible computer software systems popular streaming services include video sharing website youtube netflix amazon video vudu stream films television shows spotify apple music stream music video game live streaming sites twitch mixer early 1920s george o. squier granted patents system transmission distribution signals electrical lines technical basis later became muzak technology streaming continuous music commercial customers without use radio attempts display media computers date back earliest days computing mid-20th century however little progress made several decades primarily due high cost limited capabilities computer hardware late 1980s 1990s consumer-grade personal computers became powerful enough display various media primary technical issues related streaming enough cpu power bus bandwidth support required data rates creating low-latency interrupt paths operating system prevent buffer underrun enabling skip-free streaming content however computer networks still limited mid-1990s audio video media usually delivered non-streaming channels downloading digital file remote server saving local drive end user computer storing digital file playing back cd-roms 1991 first commercial ethernet switch see network switch introduced enabled powerful computer networks leading first streaming video solutions see business developments used schools corporations expanding bloomberg television worldwide mid 1990s world wide web established streaming audio would practical years later practical streaming media made possible advances data compression due impractically high bandwidth requirements uncompressed media raw digital audio encoded pulse-code modulation pcm requires bandwidth 1.4mbps uncompressed cd audio raw digital video requires bandwidth 168mbps sd video 1gbps fhd video important compression technique enabled practical streaming media discrete cosine transform dct form lossy compression conceived 1972 nasir ahmed developed algorithm t. natarajan k. r. rao university texas 1973 dct algorithm basis first practical video coding format h.261 1988 initially used online video conferencing followed dct-based video coding standards notably mpeg video formats 1991 onwards dct algorithm adapted modified discrete cosine transform mdct j. p. princen a. w. johnson b. bradley university surrey 1987 mdct algorithm fundamental mp3 audio format introduced 1994 especially widely used advanced audio coding aac format introduced 1999 late 1990s early 2000s users increased access computer networks especially internet early 2000s users access increased network bandwidth especially last mile technological improvements facilitated streaming audio video content computer users homes workplaces also increasing use standard protocols formats tcp/ip http html internet became increasingly commercialized led infusion investment sector band severe tire damage first group perform live internet june 24 1993 band playing gig xerox parc elsewhere building scientists discussing new technology mbone broadcasting internet using multicasting proof parc technology band performance broadcast could seen live australia elsewhere march 2017 interview band member russ haines stated band used approximately half total bandwidth internet stream performance 152-by-76 pixel video updated eight twelve times per second audio quality best bad telephone connection microsoft research developed microsoft tv application compiled ms windows studio suite tested conjunction connectix quickcam realnetworks also pioneer streaming media markets broadcast baseball game new york yankees seattle mariners internet 1995 first symphonic concert internet took place paramount theater seattle washington november 10 1995 concert collaboration seattle symphony various guest musicians slash guns n roses velvet revolver matt cameron soundgarden pearl jam barrett martin screaming trees word magazine launched 1995 featured first-ever streaming soundtracks internet metropolitan opera live hd program metropolitan opera streams opera performance live performance taking place 2013–2014 10 operas transmitted via satellite least 2,000 theaters 66 countries term streaming first used tape drives made data electronics inc. drives meant slowly ramp run entire track slow ramp times resulted lower drive costs making competitive product streaming applied early 1990s better description video demand later live video ip networks first done starlight networks video streaming real networks audio streaming time video usually referred store forward video misleading nomenclature first commercial streaming product appeared late 1992 named starworks starworks enabled demand mpeg-1 full motion videos randomly accessed corporate ethernet networks starworks starlight networks also pioneered live video streaming ethernet via internet protocol satellites hughes network systems early companies created streaming media technology include realnetworks known progressive networks protocomm prior wide spread world wide web usage web became popular late 90s streaming video internet blossomed startups vdonet acquired realnetworks precept acquired cisco microsoft developed media player known activemovie 1995 allowed streaming media included proprietary streaming format precursor streaming feature later windows media player 6.4 1999 june 1999 apple also introduced streaming media format quicktime 4 application later also widely adopted websites along realplayer windows media streaming formats competing formats websites required user download respective applications streaming resulted many users three applications computer general compatibility 2000 industryview.com launched world largest streaming video archive website help businesses promote webcasting became emerging tool business marketing advertising combined immersive nature television interactivity web ability collect data feedback potential customers caused technology gain momentum quickly around 2002 interest single unified streaming format widespread adoption adobe flash prompted development video streaming format flash format used flash-based players video hosting sites first popular video streaming site youtube founded steve chen chad hurley jawed karim 2005 initially used flash-based player played mpeg-4 avc video aac audio defaults html5 video increasing consumer demand live streaming prompted youtube implement new live streaming service users company currently also offers secured link returning available connection speed user recording industry association america riaa revealed 2015 earnings report streaming services responsible 34.3 percent year total music industry revenue growing 29 percent previous year becoming largest source income pulling around 2.4 billion us streaming revenue grew 57 percent 1.6 billion first half 2016 accounted almost half industry sales advances computer networking combined powerful home computers modern operating systems made streaming media practical affordable ordinary consumers stand-alone internet radio devices emerged offer listeners no-computer option listening audio streams audio streaming services become increasingly popular recent years streaming music hit record 118.1 billion streams 2013 general multimedia content large volume media storage transmission costs still significant offset somewhat media generally compressed storage streaming increasing consumer demand streaming high definition hd content led industry develop number technologies wirelesshd itu-t g.hn optimized streaming hd content without forcing user install new networking cables 1996 digital pioneer marc scarpa produced first large-scale online live broadcast history adam yauch-led tibetan freedom concert event would define format social change broadcasts scarpa continued pioneer streaming media world projects woodstock '99 townhall president clinton recently covered ca campaign tell friend get covered live streamed youtube media stream streamed either live demand live streams generally provided means called true streaming true streaming sends information straight computer device without saving file hard disk on-demand streaming provided means called progressive streaming progressive download progressive streaming saves file hard disk played location on-demand streams often saved hard disks servers extended amounts time live streams available one time e.g. football game streaming media increasingly coupled use social media example sites youtube encourage social interaction webcasts features live chat online surveys user posting comments online furthermore streaming media increasingly used social business e-learning due popularity streaming medias many developers introduced free hd movie streaming apps people use smaller devices tablets smartphones everyday purposes horowitz research state pay tv ott svod 2017 report said 70 percent viewing content streaming service 40 percent tv viewing done way twice number five years earlier millennials report said streamed 60 percent content one movie streaming industry largest impacts dvd industry effectively met demise mass popularization online content rise media streaming caused downfall many dvd rental companies blockbuster july 2015 new york times published article netflix dvd services stated netflix continuing dvd services 5.3 million subscribers significant drop previous year hand streaming services 65 million members march 2016 study assessing “ impact movie streaming traditional dvd movie rental ” found respondents purchase dvd movies nearly much anymore streaming taken market according study viewers find movie quality significantly different dvd online streaming issues respondents believed needed improvement movie streaming included functions fast forwarding rewinding well search functions article highlighted quality movie streaming industry would increase time advertising revenue continued soar yearly basis throughout industry providing incentive quality content production music streaming one popular ways consumers interact streaming media age digitization private consumption music transformed public good largely due one player market napster napster peer-to-peer p2p file sharing network users could upload download mp3 files freely broke music industry conventions launched early 1999 hull massachusetts platform developed shawn john fanning well sean parker interview 2009 shawn fanning explained napster “ something came result seeing sort unmet need passion people able find music particularly lot obscure stuff ’ something go record store purchase felt like problem worth solving. ” development disrupt music industry making songs previously required payment acquire freely accessible napster user demonstrated power p2p networks turning digital file public shareable good brief period time napster existed mp3 files fundamentally changed type good songs longer financially excludable barring access computer internet access rival meaning one person downloaded song diminish another user napster like providers public goods faced problem free riding every user benefits individual uploads mp3 file requirement mechanism forces users share music thus napster users incentivized let others upload music without sharing files structure revolutionized consumer ’ perception ownership digital goods made music freely replicable napster quickly garnered millions users growing faster business history peak existence napster boasted 80 million users globally site gained much traffic many college campuses block access napster created network congestion many students sharing music files advent napster sparked creation numerous p2p sites including limewire 2000 bittorrent 2001 pirate bay 2003 reign p2p networks short lived first fall napster 2001 numerous lawsuits filed napster various record labels subsidiaries universal music group sony music entertainment warner music group emi addition recording industry association america riaa also filed lawsuit napster grounds unauthorized distribution copyrighted material ultimately led napster shutting 2001 interview gary stiffelman represents eminem aerosmith tlc explained napster problem record labels loss revenue interview new york times stiffelman said “ ’ opponent artists ’ music included services ’ opponent revenue shared lawsuit records inc. v. napster inc. fundamentally changed way consumers interact music streaming argued october 2 2000 decided february 12 2001 court appeals ninth circuit ruled p2p file sharing service could held liable contributory vicarious infringement copyright serving landmark decision intellectual property law first issue court addressed “ fair use ” says otherwise infringing activities permissible long purposes “ criticism comment news reporting teaching ... scholarship research. ” judge beezer judge case noted napster claimed services fit “ three specific alleged fair uses sampling users make temporary copies work purchasing space-shifting users access sound recording napster system already audio cd format permissive distribution recordings new established artists. ” judge beezer found napster fit criteria instead enabling users repeatedly copy music would affect market value copyrighted good second claim plaintiffs napster actively contributing copyright infringement since knowledge widespread file sharing platform since napster took action reduce infringement financially benefited repeated use court ruled p2p site court found “ much eighty-seven percent files available napster may copyrighted seventy percent may owned administered plaintiffs. ” injunction ordered napster ended brief period music streaming public good non-rival non-excludable nature p2p networks success sharing mp3 ’ though met similar fate court ruling set precedent copyrighted digital content freely replicated shared unless given consent owner thereby strengthening property rights artists record labels alike although music streaming longer freely replicable public good streaming platforms spotify deezer apple music soundcloud prime music shifted music streaming club-type good platforms notably spotify give customers access freemium service enables use limited features exposure advertisements companies operate premium subscription model circumstances music streaming financially excludable requiring customers pay monthly fee access music library non-rival since one customer ’ use impair another ’ music streaming platforms grown rapidly popularity recent years spotify 207 million users january 1 2019 78 different countries apple music 60 million soundcloud 175 million platforms provide varying degrees accessibility apple music prime music offer services paid subscribers whereas spotify soundcloud offer freemium premium services napster owned rhapsody since 2011 resurfaced music streaming platform offering subscription based services 4.5 million users january 2017 music streaming providers proliferated competition pushed price subscriptions music piracy rates also fallen see chart right music industry ’ response music streaming initially negative along music piracy streaming services disrupted market contributed fall revenue 14.6 billion revenue 1999 6.3 billion 2009 u.s. cd ’ single-track downloads selling content freely available internet result record labels invested artists “ safe ” chart music became appealing producers bands unique sounds 2018 however music streaming revenue exceeded traditional revenue streams e.g record sales album sales downloads 2017 alone saw 41.1 increase streaming revenue alone 8.1 increase overall revenue streaming revenue one largest driving forces behind growth music industry interview jonathan dworkin senior vice president strategy business development universal said “ afraid perpetual change dynamism driving growth. ” broadband speed 2 mbit/s recommended streaming standard definition video without experiencing buffering skips especially live video example roku apple tv google tv sony tv blu-ray disc player 5 mbit/s recommended high definition content 9 mbit/s ultra-high definition content streaming media storage size calculated streaming bandwidth length media using following formula single user file requires storage size megabytes equal length seconds × bit rate bit/s 8 × 1024 × 1024 example one hour digital video encoded 300 kbit/s typical broadband video 2005 usually encoded 320 × 240 pixels window size 3,600 × 300,000 bit/s 8×1024×1024 requires around 128 mb storage file stored server on-demand streaming stream viewed 1,000 people time using unicast protocol requirement 300 kbit/s × 1,000 300,000 kbit/s 300 mbit/s bandwidth equivalent around 135 gb per hour using multicast protocol server sends single stream common users therefore stream would use 300 kbit/s serving bandwidth see information protocols calculation live streaming similar assuming seed encoder 500 kbit/s show lasts 3 hours 3,000 viewers calculation number mbs transferred encoder speed bit/s × number seconds × number viewers 8*1024*1024 results calculation follows number mbs transferred 500 x 1024 bit/s × 3 × 3,600 3 hours × 3,000 number viewers 8*1024*1024 1,977,539 mb audio stream compressed make file size smaller using audio coding format mp3 vorbis aac opus video stream compressed using video coding format make file size smaller video coding formats include h.264 hevc vp8 vp9 encoded audio video streams assembled container bitstream mp4 flv webm asf isma bitstream delivered streaming server streaming client e.g. computer user internet-connected laptop using transport protocol adobe rtmp rtp 2010s technologies apple hls microsoft smooth streaming adobe hds non-proprietary formats mpeg-dash emerged enable adaptive bitrate streaming http alternative using proprietary transport protocols often streaming transport protocol used send video event venue cloud transcoding service cdn uses http-based transport protocols distribute video individual homes users streaming client end user may interact streaming server using control protocol mms rtsp quality interaction servers users based workload streaming service users attempt access service quality affected unless enough bandwidth host using enough proxy networks designing network protocol support streaming media raises many problems datagram protocols user datagram protocol udp send media stream series small packets simple efficient however mechanism within protocol guarantee delivery receiving application detect loss corruption recover data using error correction techniques data lost stream may suffer dropout real-time streaming protocol rtsp real-time transport protocol rtp real-time transport control protocol rtcp specifically designed stream media networks rtsp runs variety transport protocols latter two built top udp another approach seems incorporate advantages using standard web protocol ability used streaming even live content adaptive bitrate streaming http adaptive bitrate streaming based http progressive download contrary previous approach files small compared streaming packets much like case using rtsp rtp reliable protocols transmission control protocol tcp guarantee correct delivery bit media stream however accomplish system timeouts retries makes complex implement also means data loss network media stream stalls protocol handlers detect loss retransmit missing data clients minimize effect buffering data display delay due buffering acceptable video demand scenarios users interactive applications video conferencing experience loss fidelity delay caused buffering exceeds 200 ms. unicast protocols send separate copy media stream server recipient unicast norm internet connections scale well many users want view television program concurrently multicast protocols developed reduce server/network loads resulting duplicate data streams occur many recipients receive unicast content streams independently protocols send single stream source group recipients depending network infrastructure type multicast transmission may may feasible one potential disadvantage multicasting loss video demand functionality continuous streaming radio television material usually precludes recipient ability control playback however problem mitigated elements caching servers digital set-top boxes buffered media players ip multicast provides means send single media stream group recipients computer network multicast protocol usually internet group management protocol used manage delivery multicast streams groups recipients lan one challenges deploying ip multicast routers firewalls lans must allow passage packets destined multicast groups organization serving content control network server recipients i.e. educational government corporate intranets routing protocols protocol independent multicast used deliver stream content multiple local area network segments mass delivery content multicast protocols need much less energy resources widespread introduction reliable multicast broadcast-like protocols preferential use wherever possible significant ecological economic challenge peer-to-peer p2p protocols arrange prerecorded streams sent computers prevents server network connections becoming bottleneck however raises technical performance security quality business issues useful – typical – applications streaming concept example long video lectures performed online internet advantage presentation lectures long although always interrupted repeated arbitrary places also new marketing concepts example berlin philharmonic orchestra sells internet live streams whole concerts instead several cds similar fixed media so-called digital concert hall using youtube trailing purposes online concerts also spread lot different places – cinemas – various places globe similar concept used metropolitan opera new york many successful startup ventures based business streaming media also livestream international space station media live streamed recorded certain media players vlc player use screen recorder live-streaming platforms twitch may also incorporate video demand system allows automatic recording live broadcasts watched later popular site youtube also recordings live broadcasts including television shows aired major networks streams potential recorded anyone access whether legally otherwise streaming copyrighted content involve making infringing copies works question recording distribution streamed content also issue many companies rely revenue based views attendance net greenhouse gas emissions streaming music estimated 200 350 million kilograms per year united states according 2019 study increase emissions pre-digital music period estimated 140 million kilograms 1977 136 million kilograms 1988 157 million 2000 several ways decrease ghgs associated streaming music including efforts make data centers carbon neutral converting electricity produced renewable sources individual level purchase physical cd may environmentally friendly played 27 times another option reducing energy use downloading music offline listening reduce need streaming distance spotify service built-in local cache reduce necessity repeating song streams
|
Distributed computing architecture
|
session initiation protocol session initiation protocol sip signaling protocol used initiating maintaining terminating real-time sessions include voice video messaging applications sip used signaling controlling multimedia communication sessions applications internet telephony voice video calls private ip telephone systems instant messaging internet protocol ip networks well mobile phone calling lte volte protocol defines specific format messages exchanged sequence communications cooperation participants sip text-based protocol incorporating many elements hypertext transfer protocol http simple mail transfer protocol smtp call established sip may consist multiple media streams separate streams required applications text messaging exchange data payload sip message sip works conjunction several protocols specify carry session media commonly media type parameter negotiation media setup performed session description protocol sdp carried payload sip messages sip designed independent underlying transport layer protocol used user datagram protocol udp transmission control protocol tcp stream control transmission protocol sctp secure transmissions sip messages insecure network links protocol may encrypted transport layer security tls transmission media streams voice video sdp payload carried sip messages typically employs real-time transport protocol rtp secure real-time transport protocol srtp sip originally designed mark handley henning schulzrinne eve schooler jonathan rosenberg 1996 protocol standardized 1999 november 2000 sip accepted 3gpp signaling protocol permanent element ip multimedia subsystem ims architecture ip-based streaming multimedia services cellular networks june 2002 specification revised various extensions clarifications published since sip designed provide signaling call setup protocol ip-based communications supporting call processing functions features present public switched telephone network pstn vision supporting new multimedia applications extended video conferencing streaming media distribution instant messaging presence information file transfer internet fax online games sip distinguished proponents roots internet community rather telecommunications industry sip standardized primarily ietf protocols h.323 traditionally associated international telecommunication union itu sip involved signaling operations media communication session primarily used set terminate voice video calls sip used establish two-party unicast multiparty multicast sessions also allows modification existing calls modification involve changing addresses ports inviting participants adding deleting media streams sip also found applications messaging applications instant messaging event subscription notification sip works conjunction several protocols specify media format coding carry media call set call setup body sip message contains session description protocol sdp data unit specifies media format codec media communication protocol voice video media streams typically carried terminals using real-time transport protocol rtp secure real-time transport protocol srtp every resource sip network user agents call routers voicemail boxes identified uniform resource identifier uri syntax uri follows general standard syntax also used web services e-mail uri scheme used sip sip typical sip uri form nowiki sip username domainname /nowiki nowiki sip username hostport /nowiki domainname requires dns srv records locate servers sip domain hostport ip address fully qualified domain name host port secure transmission required scheme sips used sip employs design elements similar http request response transaction model transaction consists client request invokes particular method function server least one response sip reuses header fields encoding rules status codes http providing readable text-based format sip carried several transport layer protocols including transmission control protocol tcp user datagram protocol udp stream control transmission protocol sctp sip clients typically use tcp udp port numbers 5060 5061 sip traffic servers endpoints port 5060 commonly used non-encrypted signaling traffic whereas port 5061 typically used traffic encrypted transport layer security tls sip-based telephony networks often implement call processing features signaling system 7 ss7 special sip protocol extensions exist although two protocols different ss7 centralized protocol characterized complex central network architecture dumb endpoints traditional telephone handsets sip client-server protocol equipotent peers sip features implemented communicating endpoints traditional ss7 architecture use switching centers network elements use session initiation protocol communication called sip user agents user agent ua performs function user agent client uac requesting service function user agent server uas responding request thus two sip endpoints may principle operate without intervening sip infrastructure however network operational reasons provisioning public services users directory services sip defines several specific types network server elements service elements also communicates within client-server model implemented user agent clients servers user agent logical network end-point sends receives sip messages manages sip sessions user agents client server components user agent client uac sends sip requests user agent server uas receives requests returns sip response unlike network protocols fix roles client server e.g. http web browser acts client never server sip requires peers implement roles roles uac uas last duration sip transaction sip phone ip phone implements client server functions sip user agent provides traditional call functions telephone dial answer reject call hold call transfer sip phones may implemented hardware device softphone vendors increasingly implement sip standard telephony platform distinction hardware-based software-based sip phones blurred sip elements implemented basic firmware functions many ip-capable communications devices smartphones sip http user agent may identify using message header field user-agent containing text description software hardware product name user agent field sent request messages means receiving sip server evaluate information perform device-specific configuration feature activation operators sip network elements sometimes store information customer account portals useful diagnosing sip compatibility problems display service status proxy server network server uac uas components functions intermediary entity purpose performing requests behalf network elements proxy server primarily plays role routing meaning job ensure request sent another entity closer targeted user proxies also useful enforcing policy determining whether user allowed make call proxy interprets necessary rewrites specific parts request message forwarding sip proxy servers route messages one destination called forking proxies forking sip requests means multiple dialogs established single request explains need two-sided dialog identifier without contribution recipients originator could disambiguate multiple dialogs established single request sip forking refers process forking single sip call multiple sip endpoints powerful feature sip single call ring many endpoints time sip forking allows desk phone ring time mobile allowing call taken either device redirect server user agent server generates 3xx redirection responses requests receives directing client contact alternate set uris redirect server allows proxy servers direct sip session invitations external domains registrar sip endpoint provides location service accepts register requests recording address parameters user agent subsequent requests provides essential means locate possible communication peers network location service links one ip addresses sip uri registering agent multiple user agents may register uri result registered user agents receive calls uri sip registrars logical elements often co-located sip proxies improve network scalability location services may instead located redirect server session border controllers serve middle boxes user agents sip servers various types functions including network topology hiding assistance nat traversal gateways used interconnect sip network networks public switched telephone network use different protocols technologies sip text-based protocol syntax similar http two different types sip messages requests responses first line request method defining nature request request-uri indicating request sent first line response response code requests initiate functionality protocol sent user agent client server answered one sip responses return result code transaction generally indicate success failure state transaction responses sent user agent server indicating result received request several classes responses recognized determined numerical range result codes sip defines transaction mechanism control exchanges participants deliver messages reliably transaction state session controlled various timers client transactions send requests server transactions respond requests one responses responses may include provisional responses response code form 1xx one multiple final responses 2xx – 6xx transactions categorized either type invite type non-invite invite transactions differ establish long-running conversation referred dialog sip include acknowledgment ack non-failing final response e.g. 200 ok session initiation protocol instant messaging presence leveraging extensions simple sip-based suite standards instant messaging presence information message session relay protocol msrp allows instant message sessions file transfer sip developer community meets regularly conferences organized sip forum test interoperability sip implementations ttcn-3 test specification language developed task force etsi stf 196 used specifying conformance tests sip implementations developing sip software deploying new sip infrastructure important test capability servers ip networks handle certain call load number concurrent calls number calls per second sip performance tester software used simulate sip rtp traffic see server ip network stable call load software measures performance indicators like answer delay answer/seizure ratio rtp jitter packet loss round-trip delay time sip connection marketing term voice internet protocol voip services offered many internet telephony service providers itsps service provides routing telephone calls client private branch exchange pbx telephone system public switched telephone network pstn services may simplify corporate information system infrastructure sharing internet access voice data removing cost basic rate interface bri primary rate interface pri telephone circuits sip trunking similar marketing term preferred service used simplify telecom infrastructure sharing carrier access circuit voice data internet traffic removing need primary rate interface pri circuits sip-enabled video surveillance cameras initiate calls alert operator events motion objects protected area sip used audio ip broadcasting applications provides interoperable means audio interfaces different manufacturers make connections one another u.s. national institute standards technology nist advanced networking technologies division provides public-domain java implementation serves reference implementation standard implementation work proxy server user agent scenarios used numerous commercial research projects supports full number extension rfcs including event notification reliable provisional responses numerous commercial open-source sip implementations exist see list sip software sip-i session initiation protocol encapsulated isup protocol used create modify terminate communication sessions based isup using sip ip networks services using sip-i include voice video telephony fax data sip-i sip-t two protocols similar features notably allow isup messages transported sip networks preserves detail available isup header important many country-specific variants isup implemented last 30 years always possible express detail using native sip message sip-i defined itu-t whereas sip-t defined via ietf rfc route concerns security calls via public internet addressed encryption sip protocol secure transmission uri scheme sips used mandate hop request forwarded target domain must secured transport layer security tls last hop proxy target domain user agent secured according local policies tls protects attackers try listen signaling link provide end-to-end security prevent espionage law enforcement interception encryption hop-by-hop every single intermediate proxy trusted end-to-end security may also achieved secure tunneling ipsec service providers offer secure connections use tls securing signaling tls connections use uris form nowiki sips user example.com /nowiki media streams separate connections signaling stream may encrypted secure real-time transport protocol srtp key exchange srtp performed sdes zrtp one may also add mikey exchange sip determine session keys use srtp
|
Internet protocols
|
enterprise storage os enterprise storage os also known esos linux distribution serves block-level storage server storage area network san esos composed open-source software projects required linux distribution several proprietary build install time options scst project core component esos provides back-end storage functionality esos niche linux distribution esos intended run usb flash drive type removable media secure digital compactflash etc esos memory resident operating system boot tmpfs file system initialized root file system usb flash drive image copied onto file system configuration files logs periodically written usb flash drive persistent storage user intervention configuration changes occur esos utilizes text-based user interface tui system management network configuration storage provisioning functions tui used esos written c ncurses cdk libraries used esos supports connectivity several different front-end storage area network technologies core functions supported scst third-party target drivers vendors developed scst open-source software projects commodity computing server hardware used back-end side provide underlying storage utilized front-end target interfaces esos differs popular linux distributions bootable iso image provided esos consists one archive file extracted local computer running supported operating system linux windows mac os x local computer used installing esos image usb flash drive removable media device users esos extract archive execute esos install script esos installer script prompts user installation target device writes image allow users integrate proprietary cli raid controller utilities esos usb flash drive january 16 2019 commit bfb8c55 license esos project changed gnu general public license gpl apache license version 2.0
|
Computer architecture
|
dos/v dos/v japanese computing initiative starting 1990 allow dos ibm pc compatibles vga cards handle double-byte dbcs japanese text via software alone developed ibm ps/55 machines localized version ps/2 kanji fonts locale information stored hard disk rather special chips preceding ax architecture ax great value japanese computing industry allowing compatibility foreign software possible nec proprietary pc-98 system market leader dos/v emerged dos/v stands disk operating system/vga version 5 dos/v came approximately time dos 5 promotion dos/v done ibm consortium called pc open architecture developers group oadg digital research released japanese dos/v compatible version dr dos 6.0 1992 early 1980s ibm japan released two x86-based personal computer lines asian-pacific region ibm 5550 ibm jx 5550 read kanji fonts disk drew text graphic characters 1024×768 high resolution monitor jx extended ibm pcjr ibm pc architecture supported english japanese version pc dos 720×512 resolution monitor machines could n't break dominant nec pc-98 consumer market japan 5550 expensive mostly sold large enterprises used ibm mainframes jx used 8088 processor instead faster 8086 processor ibm thought consumer product jx must n't surpass business-class 5550 damaged buyer reputations whatever actual speed another point software company said ibm uncooperative developing jx softwares ibm japan planned 100 pc/xt compatible machine codenamed jx2 cancelled 1986 masahiko hatori developer jx dos 1987 started developing dos/v spare time ibm yamato development laboratory era toshiba released japanese version t3100 laptop microsoft introduced ax architecture months later ibm japan released ps/55 model 5535 proprietary laptop using special version dos hatori thought ibm need shift proprietary pc ibm pc compatibles bosses tsutomu maruyama nobuo mii thought japan closed pc market needed changed attempt could n't done ibm alone summer 1989 decided carry development dos/v disclose architecture ps/55 found pc open architecture developers group oadg dos/v development team designed dos/v simple better scalability compatibility original pc dos difficulty reducing text drawing time stopwatch necessity dos/v development hatori said first version dos/v introduced 11 october 1990 shipped november 1990 announcement letter said designed low-end desktops laptops ps/55 users reported bbs could run dos/v ibm pc clones development team confirmed comments modified incompatibilities dos/v secret inside company would prevent sales ps/55 meet opposition hatori said maruyama mii convince ibm branches agree plan beginning december 1990 maruyama went ibm management committee presented plan low-end pc strategy japan committee usual topic took 15 minutes topic took hour plan finally approved john akers committee microsoft japan got contract ibm japan receive source code dos/v 20 december 1990 ibm japan announced founded oadg microsoft would supply dos/v pc manufacturers 1992 1994 japanese manufacturers begun selling ibm pc clones dos/v global manufacturers entered japanese market compaq 1992 dell 1993 fujitsu released ibm pc clones fmv series october 1993 200,000 units shipped 1994 microsoft japan released first retail versions windows windows 3.1 dos/v pc-98 dos/v contributed dawn ibm pc clones japan yet pc-98 kept 50 market share 1996 changed release windows 95 pc dos versions dos/v j japanese p chinese prc taiwanese h korean ms-dos versions dos/v dr dos versions dos/v
|
Computer architecture
|
session announcement protocol session announcement protocol sap experimental protocol broadcasting multicast session information sap published ietf rfc 2974 sap typically uses session description protocol sdp format real-time transport protocol session descriptions announcement data sent using ip multicast user datagram protocol sap senders periodically broadcast sdp descriptions well-known multicast address port sap listening application listen sap multicasts construct guide advertised multicast sessions announcement interval cooperatively modulated sap announcements multicast delivery scope default consume 4000 bits per second regardless maximum announce interval 300 seconds 5 minutes announcements automatically expire 10 times announcement interval one hour whichever greater announcements may also explicitly withdrawn original issuer sap features separate methods authenticating encrypting announcements use encryption recommended authentication prevents unauthorized modification dos attacks authentication optional two authentication schemes supported message body may optionally compressed using zlib format defined rfc 1950 vlc media player monitors sap announcements presents user list available streams. /ref sap one optional discovery connection management techniques described aes67 audio-over-ethernet interoperability standard
|
Internet protocols
|
boxbe boxbe free service prioritizes screens spam personal email users select email want receive email goes spam presents challenge sender requires human response bulk anonymous data provided parent company provides email validation tracking service boxbe starts user allowing boxbe access user email contacts boxbe gives priority contacts users allow integration within gmail including google apps aol yahoo mail affiliates lets boxbe stay date screen email one way boxbe promotes service sending email addresses member guest list boxbe founded 2005 thede loder corbett barr venture capital firm draper fisher jurvetson esther dyson investors dyson steve jurvetson serving board members way filter spam beyond challenge response boxbe initially used option allowing recipients define price senders must risk deliver initial message paying fee deliver email called attention bond mechanism later abandoned boxbe company founder thede loder along marshall van alstyne rick wash wrote initial paper attention bond mechanism technically capable users assemble many functions whitelisting 2012 edatasource inc. purchased assets boxbe inc
|
Computer security
|
zmanda recovery manager zmanda recovery manager perl-based utility used automate backup recovery mysql databases released gnu general public license zmanda recovery manager zrm mysql used mysql dbas backup recovery live mysql databases either local remote zrm uses appropriate backup method based particular storage engine used mysql particular storage infrastructure used e.g. use snapshots instant full backups lvm zfs netapp vxfs used zmanda offers three versions zrm mysql zrm enterprise edition zrm cluster edition zrm community edition enterprise edition includes graphical installer zmanda management console zmc command-line interface plugin framework community edition freely downloadable subset enterprise edition licensed gnu gplv2 supports lvm snapshots include zmc graphical installer zrm server runs windows solaris linux distributions including red hat ubuntu backing mysql databases solaris zrm able take benefit snapshot feature zfs zrm integrated
|
Computer security
|
calxeda calxeda previously known smooth-stone company aimed provide computers based arm architecture server computers march 2011 calxeda announced 480-core server development consisting 120 quad-core arm cortex-a9 cpus calxeda claimed reduced energy consumption well better cost per throughput compared x86-based server manufacturers competed many-core server market intel amd recent arm-based server vendors marvell technology group armada xp product multi-core processor manufacturer tilera november 2011 calxeda announced energycore ecx-1000 featuring four 32-bit armv7 cortex-a9 cpu cores operating 1.1–1.4 ghz 32 kb l1 i-cache 32 kb l1 d-cache per core 4 mb shared l2 cache 1.5 w per processor 5 w per server node including 4 gb ddr3 dram 0.5 w idle chip included five 10 gigabit ethernet ports four chips carried energycard uk-headquartered company boston limited announced 2011 appliances based calxeda energycore system chip products boston appliances marketed viridis brand demonstrated november 2012 hewlett-packard used calxeda products server product known moonshot november 2011 named redstone rocket 19 december 2013 reported calxeda going restructuring widely referred shutting operation due running capital venture funding failing secure deal hewlett-packard december 2014 intellectual property developed calxeda re-emerged company called silver lining systems sls
|
Computer architecture
|
nyotron nyotron information-security company established 2009 brothers nir ofer gaist nir gaist cto sagit manor former executive verifone became ceo 2014 company based santa clara ca r office herzliya israel 2006 18-year-old nir gaist created original concept technology became nyotron flagship product paranoid 2007 ofer traveled bucharest romania develop prototype 2008 returned israel seeking support investors major general ret amos malka former director intelligence idf among first investors served nyotron first chairman board 2014 first official version paranoid shipped 2016 nyotron moved headquarters santa clara ca company launched global war room soc console 2017 began offering paranoid service managed detection response mdr service provided solution companies require protection advanced attackers unknown threats limited security staff 2018 nyotron signed distribution agreement ingram micro company published in-depth research report activities oilrig nation-state actor aka apt34 nyotron also joined anti-malware testing standards organization amtso paranoid anti-malware endpoint detection response edr technology grounded three realizations nyotron created map known good behavior operating system areas malicious activity would attempt access file systems process thread management networking registry partition modification approach called os-centric positive security automatic os behavior whitelisting language used describing “ maps ” called behavior patterns mapping bpm patented language require machine learning/artificial intelligence statistical math-based algorithm instead deterministic algorithm complexity 1 means performance n't degrade volume input os-centric positive security approach focuses “ good ” behavior operating system paranoid detects blocks known unknown malware including zero-day exploits company calls “ threat-agnostic defense ” addition protection paranoid provides visibility attack timelines root cause attacker methods ttps 2015 company raised 10 million mivtach shamir holdings investors 2017 21 million raised douglas sandra bergeron founders dgb investments investors 2018 ingram micro made strategic investment 10 million july 2017 paranoid part sc magazine endpoint security group test received 5 5 stars publication stated “ perspective breadth depth analytical capability one best best displays type ever seen. ” september 2017 nyotron labeled “ vendor watch ” enterprise management associates nyotron also named top 50 cyber security leader 2017 cyber defense magazine 2018 paranoid named “ innovator endpoint security 2018 ” cyber defense september 2018 central station released review paranoid giving 4 possible 5 stars stating “ ransomware happening many companies product solution ransomware like virus transforms changing every day product really best solution security issue protecting end-point ransomware threat. ” october 2018 icsa labs released report stating nyotron paranoid icsa labs certified advanced threat defense report goes say nyotron detected 100 441 malicious samples tested 1 false positive 721 innocuous apps test february 2019 nyotron silver cybersecurity excellence awards categories innovative cybersecurity company advanced persistent threat protection
|
Computer security
|
smbrelay smbrelay smbrelay2 computer programs used carry smb man-in-the-middle mitm attacks windows machines written sir dystic cult dead cow cdc released march 21 2001 lantacon convention atlanta georgia seven years release microsoft released patch fixed hole exploited smbrelay fix fixes vulnerability smb reflected back client forwarded another host vulnerability still exploited smbrelay receives connection udp port 139 relays packets client server connecting windows machine originating computer port 139 modifies packets necessary connecting authenticating target client disconnected smbrelay binds port 139 new ip address relay address connected directly using net use \\192.1.1.1 used networking functions built windows program relays smb traffic excluding negotiation authentication long target host remains connected user disconnect reconnect virtual ip smbrelay collects ntlm password hashes writes hashes.txt format usable l0phtcrack cracking later time port 139 privileged port requires administrator access use smbrelay must run administrator access account however since port 139 needed netbios sessions difficult block according sir dystic problem marketing standpoint microsoft wants products much backward compatibility possible continuing use protocols known issues continue leave customers risk exploitation ... yet known issues existed since day one protocol bug fundamental design flaw assume nobody used method exploit people silly took less two weeks write smbrelay smbrelay2 works netbios level across protocol netbios bound nbf nbt differs smbrelay uses netbios names rather ip addresses smbrelay2 also supports man-in-the-middling third host however supports listening one name time
|
Computer security
|
ibm systems application architecture systems application architecture saa introduced 1987 set standards computer software developed ibm saa initiative started 1987 leadership earl wheeler father saa intent implement saa ibm operating systems including mvs os/400 os/2 aix ibm version unix operating system target saa interoperability saa family saa define new standards selected among ibm existing guidelines software ibm also purchased third party software developers bachman information systems index technology inc. knowledgeware inc intended implemented uniformly across saa compliant environments standard designed make application programs look work manner across entire range company personal computing systems midrange processors system/370 processors saa labeled complex obscure potentially difficult learn lou gerstner ibm later quietly discontinued use saa umbrella 2001 saa spoken past tense however many individual components saa still use common programming interface attempted standardize compilers application programming interfaces among systems participating saa objective providing common programming interface entire ibm computer product line pcs system/3x system/370 implies saa program written ibm machine run cpi included number pieces common user access aimed providing common user interface entire ibm product line user sits pc see menus keyboards procedures would 3270 terminal hardware differences complete commonality impossible attain ibm created two cua standards basic interface ibm 3270 ibm 5250 terminals advanced interface so-called intelligent workstations pcs keyboard standardized model 101 key enhanced keyboard layout common communications services defined methods heterogeneous systems communicated ccs depended advanced program-to-program communications also known appc lu6.2 systems network architecture sna pu2.1 low entry networking peer peer networking sna management services network control three types data links supported application services provided officevision saa-compliant successor profs as/400 office office automation ad/cycle family development tools intended simplify development saa applications
|
Operating systems
|
credential guard credential guard virtualization-based isolation technology lsass prevents attackers stealing credentials could used pass hash attacks credential guard introduced microsoft windows 10 operating system windows 10 version 20h1 credential guard available enterprise edition operating system compromising system attackers often attempt extract stored credentials lateral movement network prime target lsass process stores ntlm kerberos credentials credential guard prevents attackers dumping credentials stored lsass running lsass virtualized container even user system privileges access system creates proxy process called lsaiso lsa isolated communication virtualized lsass process several generic techniques stealing credentials systems credential guard
|
Operating systems
|
directx media directx media set multimedia-related apis microsoft windows complementing directx included directanimation 2d/3d web animation directshow multimedia playback streaming media directx transform web interactivity direct3d retained mode higher level 3d graphics directshow additionally contained directx plugins audio signal processing directx video acceleration accelerated video playback directx media runtime components distributed part internet explorer directx media sdk directx sdk existed two separate sdks directx 6.0 later microsoft deprecated directx media integrated directshow key part directx media directx april 2005 directshow removed directx moved microsoft platform sdk instead directx however still required build directshow samples directshow components gradually deprecated favor newer media foundation retained mode used variety applications still implemented systems newer xp copying d3drm.dll file older version windows system32 directory 32 bit windows syswow64 directory 64 bit windows regain system-wide support
|
Operating systems
|
network behavior anomaly detection network behavior anomaly detection nbad provides one approach network security threat detection complementary technology systems detect security threats based packet signatures nbad continuous monitoring network unusual events trends nbad integral part network behavior analysis nba offers security addition provided traditional anti-threat applications firewalls intrusion detection systems antivirus software spyware-detection software security monitoring systems utilize signature-based approach detect threats generally monitor packets network look patterns packets match database signatures representing pre-identified known security threats nbad-based systems particularly helpful detecting security threat vectors 2 instances signature-based systems new zero-day attacks ii threat traffic encrypted command control channel certain botnets nbad program tracks critical network characteristics real time generates alarm strange event trend detected could indicate presence threat large-scale examples characteristics include traffic volume bandwidth use protocol use nbad solutions also monitor behavior individual network subscribers order nbad optimally effective baseline normal network user behavior must established period time certain parameters defined normal departure one flagged anomalous nbad used addition conventional firewalls applications detection malware vendors begun recognize fact including nba/nbad programs integral parts network security packages nbad technology/techniques applied number network security monitoring domains including log analysis ii packet inspection systems iii flow monitoring systems iv route analytics
|
Computer security
|
google native client google native client nacl sandboxing technology running either subset intel x86 arm mips native code portable executable sandbox allows safely running native code web browser independent user operating system allowing web apps run near-native speeds aligns google plans chrome os may also used securing browser plugins parts applications full applications zerovm demonstrate readiness technology 9 december 2011 google announced availability several new chrome-only versions games known rich processor-intensive graphics including bastion longer supported chrome web store nacl runs hardware-accelerated 3d graphics via opengl es 2.0 sandboxed local file storage dynamic loading full screen mode mouse capture also plans make nacl available handheld devices portable native client pnacl architecture-independent version pnacl apps compiled ahead-of-time pnacl recommended nacl use cases general concept nacl running native code web browser implemented activex still use full access system disk memory user-interface registry etc. native client avoids issue using sandboxing alternative sorts nacl asm.js also allows applications written c c++ compiled run browser half native speed also supports ahead-of-time compilation subset javascript hence backwards-compatible browsers support directly another alternative may initially powered pnacl webassembly october 12 2016 comment chromium issue tracker indicated google pepper native client teams destaffed may 30 2017 google announced deprecation pnacl favor webassembly although initially google planned remove pnacl first quarter 2018 removal currently planned second quarter 2019 except chrome apps native client open-source project developed google date quake xaos battle wesnoth doom lara croft guardian light dust mame well sound processing system csound ported native client native client available google chrome web browser since version 14 enabled default since version 31 portable native client pnacl pronounced pinnacle released arm implementation released march 2010. x86-64 ia-32 mips also supported run application portably pnacl must compiled architecture-agnostic stable subset llvm intermediate representation bytecode executables called pnacl executables pexes pnacl toolchain makes .pexe files nacl toolchain .nexe files magic number .nexe files 0x7f e l f elf chrome translated architecture-specific executables run nacl uses software fault detection isolation sandboxing x86-64 arm x86-32 implementation native client notable novel sandboxing method makes use x86 architecture rarely used segmentation facility native client sets x86 segments restrict memory range sandboxed code access uses code verifier prevent use unsafe instructions perform system calls prevent code jumping unsafe instruction hidden middle safe instruction native client requires indirect jumps jumps start 32-byte-aligned blocks instructions allowed straddle blocks constraints c c++ code must recompiled run native client provides customized versions gnu toolchain specifically gnu compiler collection gcc gnu binutils llvm native client licensed bsd-style license native client uses newlib c library port gnu c library gnu libc also available nacl denotes sodium chloride common table salt pun name pepper also used pepper api cross-platform open-source api creating native client modules pepper plugin api ppapi cross-platform api native client-secured web browser plugins first based netscape npapi rewritten scratch currently used chromium google chrome enable ppapi version adobe flash built-in pdf viewer 12 august 2009 page google code introduced new project pepper associated pepper plugin api ppapi set modifications npapi make plugins portable secure extension designed specifically ease implementing out-of-process plugin execution goals project provide framework making plugins fully cross-platform topics considered include continuously evolving pepper api also supports gamepads version 19 websockets version 18 google open source browser chromium web browser use new browser plug-in model 2015 pepper supported chrome chromium blink layout engine-based browsers opera mozilla firefox stated 2014 would support pepper full specification api beyond implementation chrome designed use blink layout engine private apis specific flash player plugin documented october 2016 mozilla announced re-considered exploring whether incorporate pepper api pdfium future releases firefox however steps taken one website uses nacl server let users experiment go programming language browsers groups browser developers support native client technology others chad austin imvu praised way native client bring high-performance applications web 5 penalty compared native code secure way also accelerating evolution client-side applications giving choice programming language used besides javascript id software john d. carmack praised native client quakecon 2012 saying something inside browser native client much interesting something started really pretty darn clever x86 hack way could sandbox user mode interestingly dynamic recompilation something program c c++ compiles something going -o4 optimization level completely native code pretty damn close native code could evil pointer chasings whatever want to-the-metal game developer professionals critical sandboxing technology substantial substantive interoperability issues mozilla vice president products jay sullivan said mozilla plans run native code inside browser native apps little black boxes webpage ... really believe html want focus mozilla christopher blizzard criticized nacl claiming native code evolve way source code-driven web also compared nacl microsoft activex technology plagued dll hell håkon wium lie opera cto believes nacl seems 'yearning bad old days web native client building new platform – porting old platform web ... bring complexity security issues take away focus web platform second generation sandboxing developed google gvisor intended replace nacl google cloud exact google app engine
|
Computer security
|
computational ram computational ram c-ram random-access memory processing elements integrated chip enables c-ram used simd computer also used efficiently use memory bandwidth within memory chip influential implementations computational ram came berkeley iram project vector iram v-iram combines dram vector processor integrated chip reconfigurable architecture dram radram dram reconfigurable computing fpga logic elements integrated chip simplescalar simulations show radram system conventional processor give orders magnitude better performance problems traditional dram system processor embarrassingly parallel computational problems already limited von neumann bottleneck cpu dram researchers expect total cost machine built computational ram run orders magnitude faster traditional general-purpose computer kinds problems 2011 dram process layers optimized high capacitance cpu process optimized high frequency typically twice many beol layers dram since additional layer reduces yield increases manufacturing cost chips relatively expensive per square millimeter compared dram distinct enough three approaches computational ram cpus designed built dram process technology rather cpu logic process technology specifically optimized cpus include berkeley iram project tomi technology dsp1 memory bus off-chip memory many times capacitance on-chip memory bus system separate dram cpu chips several times energy consumption iram system computer performance computational dram expected run hotter traditional dram increased chip temperatures result faster charge leakage dram storage cells computational dram expected require frequent dram refresh processor-in-/near-memory pinm refers computer processor cpu tightly coupled memory generally silicon chip chief goal merging processing memory components way reduce memory latency increase bandwidth alternatively reducing distance data needs moved reduces power requirements system much complexity hence power consumption current processors stems strategies deal avoiding memory stalls 1980s tiny cpu executed forth fabricated dram chip improve push pop forth stack-oriented programming language improved efficiency transputer also large chip memory given made early 1980s making essentially processor-in-memory notable pim projects include berkeley iram project iram university california berkeley project university notre dame pim effort
|
Computer architecture
|
list relational database management systems list relational database management systems
|
Databases
|
galaxian galaxian designed kazunori sawano worked many namco electro-mechanical shooting gallery games programmed kōichi tashiro namco set capitalize success taito space invaders massive impact video game market proving critical financial success although first video game galaxian popularized use rgb colorful enemy designs well use short jingles scrolling backgrounds one company first video games exported outside japan thanks licensing deal midway games galaxian proved critical commercial success upon release many applauding improvements invader -type games innovations 1982 sold 40,000 arcade units north america alone japan proved success pac-man followed long series sequels spin-offs multiple platforms — first galaga would usurp original popularity recognized one greatest video games time original ported numerous game consoles including atari 2600 msx family computer included multiple namco video game compilations cited one influential important video games shoot'em genre galaxian fixed shooter video game player controls starship called galaxip objective clear round aliens enemies appear formation towards top screen two escort ships labeled galaxian flagship galboss enemies make divebomb towards bottom screen shooting projectiles attempt hit player galaxip fire single shot on-screen must wait hit top able fire another due limitations hardware flagships make divebomb two red escort ships shooting three award player bonus points extra points awarded destruction flagship enemy movement increase game progresses alongside number shots enemies fire game attract mode featured short plotline titled galaxians mission destroy aliens rounds indicated small flags bottom screen galaxian designed kazunori sawano previously worked many namco electro-mechanical shooting gallery arcade games notably shoot away 1977 early game development taito released space invaders japan swept country storm helped turn video game industry highly-profitable business help capitalize game success namco president masaya nakamura ordered sawano make best post-invaders game could put vast amount pressure development team although development game lasted six months sawano made several ideas half year production began sawano team set make game anybody could play using simple best motto production — helped trim away large-scale ideas favor game could loop endlessly able use two enemy types alongside space invaders large portion game inspired star wars specifically large-scale space battles sawano wanted replicate feeling space war specifically game sound effects several back-and-forth sound effects made many rejected sawano matching vision game namco first arcade game composed synthesizer game balance important part game sawano want make game suddenly spike difficulty build-up warning development team made number enemies on-screen gradually increased difficulty player progresses becoming noticeable later stages enemies designed personality programmed monitor player movements make attacks based early development sawano envisioned enemies resemble tie fighters star wars save hardware memory processing programmers created tilemap hardware model created set 8x8 pixel tiles — reduced processing memory requirements upwards 64 times compared framebuffer model used space invaders galaxian released namco japan november 1979 following large success namco approached midway games terms releasing game overseas midway previously lost license taito success space invaders west midst trying find new partner releasing games agreed deal released game north america early 1980 — move helped strengthen midway challenged atari leadership market help keep demand game japan namco would license game companies manufacturing cabinets including taito irem galaxian critical commercial success upon release 1982 sold 40,000 arcade units north america japan would outperform pac-man short critics applauded game use true color graphics improving formula established space invaders april 5 1980 issue cashbox noted game colorful attractive cabinet design april 26 issue called earthshaking hit referring true followup space invaders video magazine 1982 reviewed astrocade version galaxian named galactic invasion noting graphics inferior coin-op pc versions praising play-action magnificent compared console versions astrocade version would later awarded certificate merit best arcade-to-home video game translation 4th annual arkie awards 2007 retrospective review sir clive eurogamer labeled masterpiece praising beautifully drawn game graphics intense gameplay historically important game industry home computing weekly 1983 gave spectrum version galaxian 3/5 stars describing well-written version praising graphics fast although flickery softline 1983 criticized atari 8-bit version game shipped rom cartridge raised cost stated game becomes tedious quickly atari inc. published ports galaxian systems—atari 8-bit family atari 2600 atari 5200— 1982-3 three years galaxian appeared arcades year galaga additional ports published atarisoft label apple ii colecovision commodore 64 vic-20 ibm pc zx spectrum ports companies sold msx europe japan nec pc-8801 famicom japan sharp x1 bally astrocade version published galaxian name later changed galactic invasion coleco released stand-alone mini-arcade tabletop version galaxian 1981 along pac-man donkey kong frogger sold three million units combined entex released handheld electronic game called galaxian 2 1981 game called galaxian 2 two-player mode sequel entex galaxian galaxian would spawn long series sequels spin-offs multiple game platforms including arcade hardware home video game systems first galaga released year later 1981 usurping original popularity cited one greatest video games time becoming popular game golden age arcade video games north america followed gaplus 1984 added power-up items juggling-based bonus stages galaga '88 released 1987 published north america atari games featured branching level paths new enemy types multiple endings 1990 namco produced theme-park attraction based series originally presented expo '90 moved namco wonder eggs theme park two years later rail shooter 28 players used lightguns shoot enemies projectiles smaller version arcades released 1992 followed 1996 playstation release japan europe 1995 arcade remake galaga released namco classic collection vol 1 compilation galaga arrangement game added two-player co-operative play boss fights alongside new enemy weapon types ported xbox playstation 2 gamecube 2002 part compilation disk namco museum japan-only medal game spin-off galaxian fever released 2000 part namco shooting medal series following year hasbro interactive released playstation game boy color adding side-scrolling third-person stages core gameplay 2005 playstation portable compilation namco museum battle collection includes remake galaga titled galaga arrangement relation one featured namco classic collection vol 1 game later ported ios devices 2009 renamed galaga remix 2008 namco bandai games released downloadable game xbox 360 playstation 3 galaga legions — game instead twin-stick shooter game score attack modes multiple stages followed 2011 sequel galaga legions dx branded now-defunct namco generations label galaxian included namco museum series collections across several platforms galaxian galaga bundled together game boy release arcade classic 3 galaxian released microsoft windows 1995 part microsoft return arcade game also released part pac-man arcade party 30th anniversary arcade machine game also seen jakks pacific plug play tv game controllers galaxian along galaga gaplus galaga '88 redesigned modernized iphone app compilation called galaga 30th anniversary collection released commemoration event namco bandai super impulse also released stand-alone tiny arcade version galaxian galaxian world record focus many competitive gamers since release famous galaxian rivalry british player gary whelan american perry rodgers faced apollo amusements pompano beach florida usa 6–9 april 2006 whelan held world record 1,114,550 points beaten newcomer aart van vliet netherlands scored 1,653,270 points 27 may 2009 funspot family fun center weirs beach new hampshire usa
|
Computer architecture
|
primehpc fx10 primehpc fx10 supercomputer designed manufactured fujitsu announced 7 november 2011 supercomputing conference primehpc fx10 improved commercialized version k computer first supercomputer obtain 10 pflops linpack benchmark largest configuration primehpc fx10 peak performance 23.2 pflops power consumption 22.4 mw list price us 655.4 million succeeded primehpc fx100 sparc64 xifx processors 2015 first installation primehpc fx10 university tokyo information technology center named oakleaf-fx system peak performance 1.135 pflops consists 4,800 nodes total 76,800 cores 150 tb memory 50 racks oakleaf-fx ordered november 2011 became operational april 2012 june 2012 ranked 18th fastest supercomputer 39th top500 list fastest supercomputers linpack benchmark performance 1.043 pflops june 2012 fujitsu received order republic china central weather bureau first primehpc fx10 sale outside japan system installed 2014 performance 1 pflops addition serving platform high-performance computing primehpc fx10 also intended serve software development platform k computer compatible fujitsu sold several systems k computer software development including 96-node system june 2012 kobe university graduate school informatics 384-node system august 2012 university tokyo institute solid-state physics
|
Computer architecture
|
ibm common user access common user access cua standard user interfaces operating systems computer programs developed ibm first published 1987 part systems application architecture used originally mvs/esa vm/cms os/400 os/2 microsoft windows operating systems parts cua standard implemented programs operating systems including variants unix also used java awt swing ibm wanted standard way interact text-based user interface software whether screen dumb terminal connected mainframe ps/2 vga graphics cua detailed specification set strict rules applications look function aim part bring harmony among dos applications independently implemented different user interfaces examples thus every program learned individually complete user interface memorised sign expertise learned uis dozens applications since novice user facing new program would find existing knowledge similar application either use actively hindrance understanding learned behavior might need unlearned new application detailed cua specification published december 1987 328 pages long similarities apple computer detailed human interface guidelines 139 pages apple hig detailed book specifying software 1984 apple macintosh computer look function first written mac new graphical user interface gui software novelty apple took great pains ensure programs would conform single shared look feel cua similar aim faced difficult task trying impose retroactively existing thriving chaotic industry much ambitious goal unifying ui personal computers minicomputers mainframes supporting character gui modes batch interactive designs comparison apple hig supported interactive gui standalone personal computer cua also attempted measurable standard apple hig large sections formatted checklists measure compliance cua contains standards operation elements dialog boxes menus keyboard shortcuts become influential implemented today many programmers never read cua standards seen operation windows dos-based applications like ms-dos 5 full-screen text editor edit.com cua hallmarks include cua covers dos applications also basis windows consistent user interface standard cui well os/2 applications — text-mode presentation manager gui — ibm mainframes conform systems application architecture cua attempt rationalise dos applications — part larger scheme bring together rationalise harmonise overall functions software hardware across ibm entire computing range microcomputers mainframes perhaps partly completely successful third edition cua took radical departure first two introducing object-oriented workplace changed emphasis user interactions data documents pictures user worked emphasis applications removed intention making computer easier use matching users expectations would work documents using programs rather operating programs work documents see also object-oriented user interface cua strongly influenced early microsoft windows operating system period joint ibm microsoft cooperation os/2 presentation manager later releases ibm cua documents used microsoft products cua became less significant windows environment instance start menu introduced standard keystrokes basic gui widgets specified cua remain available windows cua never significant impact design unix terminal character-mode applications preceded cua decade however major unix gui environments/toolkits whether based x window system featured varying levels cua compatibility motif/cde explicitly featuring design goal current major environments gnome kde also feature extensive cua compatibility subset cua implemented microsoft windows osf/motif generally considered de facto standard followed new unix gui environment
|
Operating systems
|
department defense cyber crime center department defense cyber crime center dc3 designated federal cyber center national security presidential directive 54/homeland security presidential directive 23 department defense dod center excellence digital multimedia d/mm forensics dod directive 5505.13e serves operational focal point defense industrial base dib cybersecurity information assurance cs/ia program dc3 operates air force office special investigations afosi osi deliver superior d/mm forensic services cyber technical training vulnerability sharing technical solutions development cyber analysis following dod mission areas cybersecurity cs critical infrastructure protection cip law enforcement counterintelligence le/ci document media exploitation domex counterterrorism ct dc3 cyber forensics laboratory dc3/cfl performs d/mm forensic examinations device repair data extraction expert testimony dod lab robust intrusion malware analysis capability supports dc3 lines business activities lab operations accredited iso 17025 american society crime laboratory directors/laboratory accreditation board ascld/lab guides reliable repeatable valid exam results subjected quality control peer review dc3 cyber training academy formerly dcita defense cyber investigations training academy provides in-residence online training dod elements protect dod information systems unauthorized use criminal fraudulent foreign intelligence activities academy curriculum offers courses organized specialty areas since founding 1998 academy recorded 35,000 student enrollments courses dc3 technical solutions development dc3/tsd directorate tailors software system solutions engineered specific requirements digital forensic examiners cyber intrusion analysts tsd validates commercial off-the-shelf cots government off-the-shelf gots in-house developed software/hardware used forensic process addition tsd functions dod repository cyber counterintelligence ci tools operational hub dib cs/ia program dib collaborative information sharing environment dc3/dcise assists dib companies safeguard dod content intellectual property residing transiting unclassified networks dcise develops shares actionable threat products performs cyber analysis diagnostics remediation consults dib partners dc3 analytical group dc3/ag supports le/ci agencies including air force office special investigations afosi naval criminal investigative services ncis key mission partners federal bureau investigation fbi member agency national cyber investigative joint task force ncijtf ag leads collaborative analytical technical exchange subject matter experts le/ci computer network defense cnd intelligence community ic information assurance ia agencies build threat picture enabling proactive le/ci cyber operations focuses nation-state threat actors 2006 2013 dc3 held free online international competition consisting individual progressive-level exercises challenges tests included stenography data carving data recovery detection malicious software first year 140 teams u.s. participated challenge final year challenge grown include 1,254 teams 53 countries dc3 hosted dod cyber crime conference 2003 2012 military criminal investigative organizations federal law enforcement
|
Computer security
|
netscreen technologies netscreen technologies american technology company acquired juniper networks us 4 billion stock stock 2004 netscreen technologies developed asic-based internet security systems appliances delivered high performance firewall vpn traffic shaping functionality internet data centers e-business sites broadband service providers application service providers netscreen first firewall manufacturer develop gigabit-speed firewall netscreen-1000 netscreen technologies founded yan ke ken xie feng deng ken xie chief technology officer co-founder also ceo robert thomas joined 1998 robert thomas netscreen president chief executive officer came netscreen 1998 sun microsystems general manager intercontinental operations sun software business includes security networking internet tools ken xie left netscreen 2000 found fortinet competing asic-based firewall company netscreen acquired core ips technology purchase onesecure inc. us 45 million stock 2002 onesecure created rakesh loonkar subsequently co-founder trusteer israeli engineer nir zuk one check point software ’ first employees 2003 netscreen hired anson chen vice president research development anson chen 12-year veteran cisco systems inc. former vice president general manager network management services technology group led engineering research development efforts netscreen entire product line including firewall ipsec virtual private network vpn intrusion detection prevention technologies chen also functional management responsibility netscreen secure access products yan ke feng deng stayed juniper acquisition left company 2005 start northern light venture capital china concept venture capital firm focused early growth stage opportunities tmt consumer clean technologies life science industries nir zuk stayed juniper acquisition left 2005 start palo alto networks analysis firmware code 2015 showed backdoor key could exist using dual_ec_drbg would enable whoever held key passively decrypt traffic encrypted screenos december 2015 juniper systems announced discovered unauthorized code screenos software underlies netscreen devices present 2012 onwards two vulnerabilities one simple root password backdoor one changing point dual_ec_drbg attackers presumably key use preexisting intentional unintentional kleptographic backdoor screenos passively decrypt traffic
|
Computer security
|
dbm computing computing dbm library file format providing fast single-keyed access data original dbm library file format simple database engine originally written ken thompson released 1979 name three letter acronym database manager also refer family database engines apis features derived original dbm dbm library stores arbitrary data use single key primary key fixed-size buckets uses hashing techniques enable fast retrieval data key hashing scheme used form extendible hashing hashing scheme expands new buckets added database meaning nearly empty database starts one bucket split becomes full two resulting child buckets split become full database grows keys added dbm library derivatives pre-relational databases manage associative arrays implemented on-disk hash tables practice offer practical solution high-speed storage accessed key require overhead connecting preparing queries balanced fact generally opened writing single process time agent daemon handle requests multiple processes introduces ipc overhead original dbm library replaced many successor implementations notable examples include 2001 ndbm implementation dbm standard solaris irix whereas berkeley db implementations standard free operating systems
|
Databases
|
blob emoji google blob emoji feature android mobile operating system 2013 2017 google introduced blobs part android kitkat mobile operating system 2013 next year google expanded blob style include emojis normally depict humans example instead flamenco dancer apple emoji style derivates google blob style showed less glamorous blob rose teeth 2016 google redesigned blobs gumdrop-shape unicode group establishes emoji standards introduced skin tone gender options emojis google emojis progressively appeared humans less yellow amorphous blobs google retired blobs 2017 release android oreo favor circular emojis similar style platforms consistent cross-platform emoji interpretation among redesign primary aims redesign development year mimicked apple effort include detail emoji glyph offer yellow skin tone default since 2017 effort maintain blob emojis google retired called blobmoji available github blob emoji divisive feature 2013 2017 proponents praised novel interpretation emoji ideograms detractors criticized miscommunication results emoji interpreted differently across platforms google released sticker packs featuring blob emoji gboard android messages 2018
|
Operating systems
|
scidb scidb column-oriented database management system dbms designed multidimensional data management analytics common scientific geospatial financial industrial applications developed paradigm4 co-created turing award winner michael stonebraker stonebraker claims arrays 100 times faster scidb relational dbms class problems swapping rows columns mathematical arrays put fewer restrictions data work number dimensions unlike conventionally widely used relational database management system model relation supports one dimension records according 2011 conference presentation scidb supports marilyn matz became chief executive company
|
Distributed computing architecture
|
hamza bendelladj hamza bendelladj arabic حمزة بن دلاج algerian hacker goes code name bx1 nicknamed smiling hacker born 1988 tizi ouzou algeria top 10 list wanted hackers interpol fbi allegedly embezzling tens millions dollars two hundred american european financial institutions via computer virus rimig33k infected 50 million computers worldwide mostly united states developed russian accomplice aleksandr andreevich panin aka gribodemon steal banking information stored infected computers hacked official website israeli government using malicious software called spyeye bendelladj pseudonyms bx1 daniel hb broke computers banks private individuals acquire passwords identification codes took control account emptied three-year hunt bendelladj arrested january 8 2013 thai police making stopover bangkok transit malaysia egypt resist arrest said goodbye family arrested wife daughter continued journey egypt without earned nickname smiling hacker due smile face media presentation photos taken arrest even handcuffed according thai police bendelladj top 10 wanted fbi asked money claimed donated millions dollars palestinian charities trial documents mention extradited may 2013 united states tried atlanta pleaded guilty june 25 2015 faced sentence 30 years prison fine fourteen million dollars accomplice aleksandr andreevich panin arrested july 1 2013 atlanta hartsfield-jackson international airport pleaded guilty january 2014 atlanta federal court 2015 tunisian website posted rumor bendelladj sentenced death rumor spread social networks algeria several facebook support groups created reaction support petition launched demanding algerian ministry foreign affairs president barack obama intervene release us ambassador algeria joan a. polaschik wrote twitter account computer crimes capital crimes punishable death penalty bendelladj prison united states since may 2013 us court sentenced april 20 2016 15 years prison 3 years probation russian accomplice panin 27 aka gribodemon sentenced 9 years 6 months prison report united states department justice estimated spyeye virus stolen approximately billion dollars 2010 2012 affected banks repaired damage caused malware bendelladj lawyer announced intended appeal court decision
|
Computer security
|
action code script action code script acs scripting language used video games modern doom source ports zdoom syntactically similar c less flexible name implies core logic script functionality comes form scripts traditionally identified numerical value later revisions acs compiler added support named scripts utilize string lieu numerical identifier simple functions similar traditional code acs compiled using acc homage c gcc utility use doom hexen etc ... scripts executed variety methods attached in-game actors execution level triggers around map invocation scripts functions entire scripting language built hack top doom id tech engine formal support object-oriented programming principles using classic hello world example basic example text hello world printed upon entering level syntax follows
|
Programming language topics
|
zeus malware zeus zeus zbot trojan horse malware package runs versions microsoft windows used carry many malicious criminal tasks often used steal banking information man-in-the-browser keystroke logging form grabbing also used install cryptolocker ransomware zeus spread mainly drive-by downloads phishing schemes first identified july 2007 used steal information united states department transportation became widespread march 2009 june 2009 security company prevx discovered zeus compromised 74,000 ftp accounts websites companies bank america nasa monster.com abc oracle play.com cisco amazon businessweek similarly koobface zeus also used trick victims technical support scams giving scam artists money pop-up messages claim user virus reality might viruses scammers may use programs command prompt event viewer make user believe computer infected zeus difficult detect even up-to-date antivirus security software hides using stealth techniques considered primary reason zeus malware become largest botnet internet damballa estimated malware infected 3.6 million pcs u.s. 2009 security experts advising businesses continue offer training users teach click hostile suspicious links emails web sites keep antivirus protection date antivirus software claim reliably prevent infection example symantec browser protection says prevent infection attempts october 2010 us fbi announced hackers eastern europe managed infect computers around world using zeus virus distributed e-mail targeted individuals businesses municipalities opened e-mail trojan software installed victimized computer secretly capturing passwords account numbers data used log online banking accounts hackers used information take victims ’ bank accounts make unauthorized transfers thousands dollars time often routing funds accounts controlled network money mules paid commission many u.s. money mules recruited overseas created bank accounts using fake documents false names money accounts mules would either wire back bosses eastern europe withdraw cash smuggle country 100 people arrested charges conspiracy commit bank fraud money laundering 90 us others uk ukraine members ring stolen 70 million 2013 hamza bendelladj known bx1 online arrested thailand deported atlanta georgia usa early reports said mastermind behind zeus accused operating spyeye bot functionally similar zeus botnets suspected also operating zeus botnets charged several counts wire fraud computer fraud abuse court papers allege 2009 2011 bendelladj others developed marketed sold various versions spyeye virus component parts internet allowed cybercriminals customize purchases include tailor-made methods obtaining victims ’ personal financial information also alleged bendelladj advertised spyeye internet forums devoted cyber- crimes operated command control servers charges georgia relate spyeye spyeye botnet control server based atlanta late 2010 number internet security vendors including mcafee internet identity claimed creator zeus said retiring given source code rights sell zeus biggest competitor creator spyeye trojan however experts warned retirement ruse expect developer return new tricks
|
Computer security
|
lorcon lorcon acronym loss radio connectivity open source network tool library injecting 802.11 wlan frames capable injecting via multiple driver frameworks without need change application code lorcon built patching third-party codice_1-driver cards based qualcomm atheros wireless chipset project maintained joshua wright michael kershaw dragorn
|
Computer security
|
orange box orange box piece hardware software generates caller id frequency-shift keying fsk signals spoof caller id information target caller id terminal
|
Computer security
|
anti-pharming anti-pharming techniques technology used combat pharming traditional methods combating pharming include server-side software dns protection web browser add-ins toolbars server-side software typically used enterprises protect customers employees use internal private web-based systems pharmed phished browser add-ins allow individual users protect phishing dns protection mechanisms help ensure specific dns server hacked thereby become facilitator pharming attacks spam filters typically provide users protection pharming currently efficient way prevent pharming end users make sure using secure web connections https access privacy sensitive sites banking taxing accept valid public key certificates issued trusted sources certificate unknown organisation expired certificate accepted time crucial business so-called active cookies provide server-side detection tool legislation also plays essential role anti-pharming march 2005 u.s senator patrick leahy d-vt introduced anti-phishing act 2005 bill proposes five-year prison sentence and/or fine individuals execute phishing attacks use information garnered online fraud phishing pharming commit crimes identity theft home users consumer-grade routers wireless access points perhaps single effective defense change password router something default replacing password susceptible dictionary attack
|
Computer security
|
integration objects integration objects software development firm created 2002 company systems integrator solutions provider knowledge management automation plant process management decision support applications develops opc software products knowledge management platforms manufacturers primarily oil gas refining petrochemicals chemical food beverage steel pharmaceutical industries also provides consulting services integration objects member opc foundation international society automation mimosa also collaborated partnered companies invensys osisoft gensym abb large projects clients include exxonmobil saudi aramco solvay chemicals opc technology follows set open standards specifications created managed opc foundation ensure interoperability devices systems industrial automation within enterprise systems origins opc based microsoft ole com dcom technology today opc set standards allow field systems devices automation control applications business applications communicate acquired real-time historical data records enterprise systems production devices multiple vendors standards evolving created rewritten account emerging technologies trends manufacturing companies invest large amounts money industrial automation infrastructures many yet realize full value investment many remain islands automation information silos disconnected systems including business systems enormous amounts data may available companies often lack proper infrastructure would allow adequately share data use improve process efficiency profitability integration process control plant-level enterprise systems longer option manufacturing energy companies want remain competitive convergence world automation process controls greatly helps effort providing economically technically competitive solutions however sharing process information within networks must done way aligns overall security policies enterprise system integrators must find customized solutions fit specific company needs goals many enterprises across various industries face issue important resources data information knowledge embedded computer systems documentation minds individuals across organization accessing extremely difficult time-consuming however using intelligent computer platforms capture integrate knowledge analyze organize store well users monitor manage operations performances effectively make safe smart decisions rapidly improve results knowledge management allows organization benefit collective knowledge written resources employees experiences know-how applications knowledge management systems found many fields example case abnormal plant conditions knowledge management platforms allow operator identify root cause problem correct action taken automatically reviewing stored analyzed data found system knowledge management strategic asset necessary organization remain competitive
|
Computer architecture
|
recoverpoint recoverpoint continuous data protection product offered dell emc supports asynchronous synchronous data replication block-based storage recoverpoint originally created company called kashya bought emc 2006 kashya founded february 2001 originally located ramat gan israel venture funding included battery ventures jerusalem global ventures 2003 additional operations san jose california announced along 12 million funding first product kashya acquired emc corporation may 9 2006 153 million emc already announced product named recoverpoint october 2005 adapted product called recovery one mendocino software kashya product named kdx 5000 emc recoverpoint product based kashya technology released 2007 version 3.0 released 2008 recoverpoint continuous data protection cdp tracks changes data block level journals changes every write tracked stored different snapshot alternatively groups writes aggregated according configuration order reduce storage space network traffic journal allows rolling data previous point-in-time order view drive contents certain data corruption cdp journal write individually hence enabling any-point-in-time snapshots configured combine consecutive writes order reduce journal space improve bandwidth cdp works storage area network recoverpoint appliances need configured replica journal logical unit numbers luns recoverpoint continuous remote replication crr enables replica remote site setup recoverpoint appliances clusters required local remote sites 2 clusters communicate either fibre channel fc internet protocol recoverpoint applies data compression data de-duplication order reduce wide area network traffic recoverpoint 3.4 one remote site crr combined cdp order provide concurrent local remote clr replication consistency group cg term used grouping several luns together order ensure write-order consistency several volumes used example database stores data journal different logical drives logical drives must kept in-sync replica data-consistency needs preserved examples multi-volume file systems zfs windows dynamic disks similar continuous data protection products unlike backup products recoverpoint needs obtain copy every write order track data changes emc advertises recoverpoint heterogenous due support multi-vendor server network storage arrays host-based write splitting done using device driver installed server accessing storage volumes usage host-based splitter allows replication selected non-emc storage available fabric-based splitters brocade communications systems san switches cisco systems santap requires investment additional switch blades configuration allows splitting operating systems regardless version agnostic storage array vendor storage array splitters supported subset emc storage products method allows write splitting operating systems require special san switching hardware recoverpoint/se slimmed-down version supports type splitter site requires installation cluster composed 2-8 recoverpoint appliances multiple appliances work together high availability cluster appliance connected via fc san must access server scsi initiator storage scsi target appliance must also connected ip network management replication takes place either fc standard internet protocol one splitters would split traffic storage appliances besides integration emc products appsync vipr replication manager control center unisphere clariion vnx symmetrix vplex storage arrays recoverpoint integrates following products integration vmware vsphere vmware site recovery manager microsoft hyper-v allows protection specified per virtual machine instead per volumes available hypervisor integration microsoft shadow copy exchange sql server oracle database server allows recoverpoint temporarily stop writes host order take consistent application-specific snapshots application programming interfaces command-line interfaces allow customers integrate custom internal software
|
Computer security
|
huawei huawei technologies co. ltd. chinese multinational technology company provides telecommunications equipment sells consumer electronics including smartphones headquartered shenzhen guangdong province company founded 1987 ren zhengfei initially focused manufacturing phone switches huawei expanded business include building telecommunications networks providing operational consulting services equipment enterprises inside outside china manufacturing communications devices consumer market huawei 188,000 employees around 76,000 engaged research development r 21 r institutes around world april 2019 opened dedicated ox horn campus dongguan company invested us 13.8 billion r huawei deployed products services 170 countries served 45 50 largest telecom operators networks numbering 1,500 reach one third world population huawei overtook ericsson 2012 largest telecommunications-equipment manufacturer world overtook apple 2018 second-largest manufacturer smartphones world behind samsung electronics ranks 72nd fortune global 500 list december 2018 huawei reported annual revenue risen us 108.5 billion 2018 21 increase 2017 although successful internationally huawei faced difficulties markets due cybersecurity allegations—primarily united states government—that huawei infrastructure equipment may enable surveillance chinese government especially development 5g wireless networks china aggressively promoted calls u.s. prevent use products huawei fellow chinese telecom zte u.s. allies huawei argued products posed greater cybersecurity risk vendor evidence u.s. espionage claims nonetheless huawei pulled u.s. consumer market 2018 concerns affected ability market consumer products u.s. measures intensified may 2019 midst ongoing trade war china united states huawei restricted commerce u.s. companies due alleged previous willful violations u.s. sanctions iran 29 june 2019 u.s. president donald trump reached agreement resume trade talks china announced would ease aforementioned sanctions huawei name huawei literally translates china hua shortened form huaxia poetic name china wei means make chinese pinyin huáwéi pronounced mandarin chinese cantonese name transliterated jyutping waa-wai pronounced however pronunciation huawei non-chinese varies countries example hoe-ah-wei netherlands company considered changing name english concerned non-chinese may find name hard pronounce decided keep name launched name recognition campaign instead encourage pronunciation closer wah-way using words wow way 1980s chinese government tried modernize country underdeveloped telecommunications infrastructure core component telecommunications network telephone exchange switches late 1980s several chinese research groups endeavored acquire develop technology usually joint ventures foreign companies ren zhengfei former deputy director people liberation army engineering corps founded huawei 1987 shenzhen company reports rmb 21,000 registered capital time founding ren sought reverse engineer foreign technologies local researchers time china telecommunications technology imported abroad ren hoped build domestic chinese telecommunication company could compete ultimately replace foreign competitors first several years company business model consisted mainly reselling private branch exchange pbx switches imported hong kong meanwhile reverse-engineering imported switches investing heavily research development manufacture technologies 1990 company approximately 600 r staff began independent commercialization pbx switches targeting hotels small enterprises company first major breakthrough came 1993 launched c c08 program controlled telephone switch far powerful switch available china time initially deploying small cities rural areas placing emphasis service customizability company gained market share made way mainstream market huawei also key contract build first national telecommunications network people liberation army deal one employee described small terms overall business large terms relationships 1994 founder ren zhengfei meeting party general secretary jiang zemin telling switching equipment technology related national security nation switching equipment like one lacked military jiang reportedly agreed assessment 1990s canadian telecom giant nortel outsourced production entire product line huawei subsequently outsourced much product engineering huawei well another major turning point company came 1996 government beijing adopted explicit policy supporting domestic telecommunications manufacturers restricting access foreign competitors huawei promoted government military national champion established new research development offices 1997 huawei contract provide fixed-line network products hong kong company hutchison whampoa later year huawei launched wireless gsm-based products eventually expanded offer cdma umts 1999 company opened research development r center bangalore india develop wide range telecom software may 2003 huawei partnered 3com joint venture known h3c focused enterprise networking equipment marked 3com re-entrance high-end core routers switch market abandoned 2000 focus businesses 3com bought huawei share venture 2006 us 882 million 2005 huawei foreign contract orders exceeded domestic sales first time huawei signed global framework agreement vodafone agreement marked first time telecommunications equipment supplier china received approved supplier status vodafone global supply chain huawei also signed contract british telecom bt deployment multi-service access network msan transmission equipment bt 21st century network 21cn 2007 huawei began joint venture u.s. security software vendor symantec corporation known huawei symantec aimed provide end-to-end solutions network data storage security huawei bought symantec share venture 2012 new york times noting symantec fears partnership would prevent obtaining united states government classified information cyberthreats may 2008 australian carrier optus announced would establish technology research facility huawei sydney october 2008 huawei reached agreement contribute new gsm-based hspa+ network deployed jointly canadian carriers bell mobility telus mobility joined nokia siemens networks huawei delivered one world first lte/epc commercial networks teliasonera oslo norway 2009 july 2010 huawei included global fortune 500 2010 list published u.s. magazine fortune first time strength annual sales us 21.8 billion net profit us 2.67 billion october 2012 announced huawei would move uk headquarters green park reading berkshire september 2017 huawei created narrowband iot city-aware network using one network one platform n applications construction model utilising iot cloud computing big data next-generation information communications technology also aims one world five largest cloud players near future april 2019 huawei established huawei malaysia global training centre mgtc cyberjaya malaysia huawei ’ first training centre outside china end 2018 huawei sold 200 million smartphones reported strong consumer demand premium range smart phones helped company reach consumer sales excess 52 billion 2018 huawei announced worldwide revenues 105.1 billion 2018 net profit 8.7 billion huawei q1 2019 revenues 39 year-over-year us 26.76 billion huawei centre espionage allegations chinese 5g network equipment 2018 united states passed defense funding bill contained passage barring federal government business huawei zte several chinese vendors surveillance products due security concerns 1 december 2018 huawei vice-chairwoman cfo meng wanzhou daughter company founder ren zhengfei arrested canada request u.s. authorities faced extradition united states charges violating sanctions iran 22 august 2018 arrest warrant issued u.s. district court eastern district new york meng charged conspiracy defraud multiple international institutions according prosecutor warrant based allegations conspiracy defraud banks clearing money claimed huawei actually skycom entity claimed entirely controlled huawei said dealing iran contrary sanctions none allegations proven court 11 december 2018 meng released bail 28 january 2019 u.s. federal prosecutors formally indicted meng huawei thirteen counts bank wire fraud order mask sale u.s. technology iran illegal sanctions obstruction justice misappropriating trade secrets department also filed formal extradition request meng canadian authorities day huawei responded charges said denies subsidiary affiliate committed asserted violations well asserted meng similarly innocent china ministry industry information technology believed charges brought united states unfair august 2018 national defense authorization act fiscal year 2019 ndaa 2019 signed law containing provision banned huawei zte equipment used u.s. federal government citing security concerns huawei filed lawsuit act march 2019 alleging unconstitutional specifically targeted huawei without granting chance provide rebuttal due process 15 may 2019 department commerce added huawei 70 foreign subsidiaries affiliates entity list export administration regulations citing company indicted knowingly willfully causing export re-export sale supply directly indirectly goods technology services banking financial services united states iran government iran without obtaining license department treasury office foreign assets control ofac restricts u.s. companies business huawei without government license various u.s.-based companies immediately froze business huawei comply regulation including google—which removes ability certify future devices updates android operating system licensed google mobile services gms google play store well broadcom intel qualcomm microsoft xilinx western digital german chipmaker infineon technologies also voluntarily suspended business huawei pending assessments reported huawei limited stockpile u.s.-sourced parts obtained prior sanctions 17 may 2019 huawei voluntarily suspended membership jedec temporary measure restrictions imposed u.s. government removed speaking chinese media huawei founder ren zhengfei accused u.s. politicians underestimating company strength explained terms 5g technologies others wo n't able catch huawei two three years sacrificed families ideal stand top world reach ideal sooner later conflict us kevin wolf international trade lawyer former assistant secretary commerce export administration obama administration argued huawei could even use open source android open source project aosp code could fall u.s. trade regulations technology u.s. origin google majority developer china normal android phones including huawei include google play store gms google business region phones typically bundled aosp-based distribution built around oem software suite including either first-party app store run oem huawei appgallery third-party service google issued statement assuring user access google play existing huawei devices would disrupted huawei made similar pledge continued support existing devices including security patches make statements regarding availability future android versions upcoming android q 19 may 2019 department commerce granted huawei temporary three-month license continue business u.s. companies purposes maintaining existing smartphone telecom products without interruption whilst long-term solutions determined 22 may 2019 arm holdings also suspended business huawei including active contracts support entitlements pending engagements although japanese-owned company based uk arm cited intellectual property contained technologies u.s. origin believed covered department commerce order prevents huawei manufacturing chips use arm architecture also reported several asian wireless carriers including japan softbank kddi taiwan chunghwa telecom taiwan mobile suspended sale upcoming huawei devices p30 lite citing uncertainties effects u.s. sanctions availability android platform ntt docomo similarly suspended pre-orders new huawei phones without citing reasoning 23 may 2019 reported sd association removed huawei list members—implicating revocation membership association day toshiba briefly suspended shipments huawei temporary measure determining whether selling u.s. made components technologies huawei panasonic also stated determined business relationship compliance u.s. law would suspend next day wi-fi alliance also temporarily restricted huawei membership 24 may 2019 huawei told reuters fedex attempted divert two packages sent japan addressed huawei china united states tried divert two packages sent vietnam huawei offices elsewhere asia without authorization first fedex china claimed media reports true may 28 however apologized chinese social media account fact small number huawei shipments misrouted claimed external parties require fedex ship shipments 29 may 2019 reported huawei listed member jedec sd association wi-fi alliance addition science organization ieee initially banned huawei employees peer-reviewing papers handling papers editors may 30th 2019 citing legal concerns ban also revoked june 3rd 2019 29 june 2019 g20 summit trump chinese president general secretary xi jinping agreed resume trade negotiations trump made statements implicating plans ease restrictions u.s. companies business huawei explaining sold tremendous amount products company exactly happy could n't sell referring equipment great national security problem bbc news considered move significant concession sanctions noted huawei working in-house operating system codenamed hongmeng os interview die welt executive richard yu stated in-house os could used plan b prevented using android windows result u.s. action would prefer work ecosystems google microsoft efforts develop in-house os huawei date back far 2012 huawei filed trademarks names ark ark os harmony europe speculated connected os june 2019 huawei communications vp andrew williamson told reuters company testing hongmeng china could ready months however july 2019 chairman liang hua senior vice president catherine chen stated hongmeng os actually intended mobile operating system smartphones actually embedded operating system designed internet things iot hardware huawei classifies collective entity prior 2019 refer private company richard mcgregor author said definitional distinction essential company receipt state support crucial points development mcgregor argued huawei status genuine collective doubtful huawei position shifted 2019 dr. song liuping huawei chief legal officer commented us government ban said politicians us using strength entire nation come private company emphasis added ren zhengfei founder ceo huawei power veto decisions made board directors huawei disclosed list board directors first time 2010 liang hua current chair board members board liang hua guo ping xu zhijun hu houkun meng wanzhou cfo deputy chairwoman currently bail vancouver arrested december 1 2018 extradition request us authorities suspicion iran sanctions evasion ding yun yu chengdong wang tao xu wenwei chen lifang peng zhongyang tingbo li yingtao ren zhengfei yao fuhai tao jingwen yan lida guo ping chairman huawei device huawei mobile phone division huawei ’ chief ethics compliance officer zhou daiqi also huawei ’ communist party committee secretary chief legal officer song liuping huawei maintains employee-owned company ren zhengfei retains approximately 1 percent shares huawei holding company huawei investment holding remainder shares held trade union committee trade union per se internal governance procedures committee members leaders selected remain unknown claimed representative huawei employee shareholders company trade union committee registered pay dues shenzhen federation all-china federation trade unions also due limitation chinese law preventing limited liability companies 50 shareholders half huawei staff participate scheme foreign employees eligible hold company calls virtual restricted shares shares nontradable allocated reward performance employees leave huawei shares revert company compensates holding although employee shareholders receive dividends shares entitle direct influence management decisions enables vote members 115-person representatives ’ commission preselected list candidates representatives ’ commission selects huawei holding board directors board supervisors scholars found stages historical morphing employees part huawei “ shares ” instead “ virtual stock contract right property right gives holder voting power either huawei tech huawei holding transferred cancelled employee leaves firm subject redemption payment huawei holding tuc low fixed price ” debate whether trade union committee structure enabling government people republic china influence huawei chinese company trade unions report senior trade union organizations turn report all-china federation trade unions controlled communist party china therefore academics considered huawei owned controlled chinese government also argued huawei much state owned enterprise party owned enterprise approximately 80 world top 50 telecoms companies worked huawei prominent partners include since 2016 german camera company leica established partnership huawei leica cameras co-engineered huawei smartphones including p mate series first smartphone co-engineered leica camera huawei p9 huawei organized around three core business segments huawei announced enterprise business january 2011 provide network infrastructure fixed wireless communication data center cloud computing solutions global telecommunications customers huawei core network solutions offer mobile fixed softswitches plus next-generation home location register internet protocol multimedia subsystems ims huawei sells xdsl passive optical network pon next-generation pon ng pon single platform company also offers mobile infrastructure broadband access service provider routers switches sprs huawei software products include service delivery platforms sdps bsss rich communication suite digital home mobile office solutions huawei global services provides telecommunications operators equipment build operate networks well consulting engineering services improve operational efficiencies include network integration services mobile fixed networks assurance services network safety learning services competency consulting huawei devices division provides white-label products content-service providers including usb modems wireless modems wireless routers mobile wi-fi embedded modules fixed wireless terminals wireless gateways set-top boxes mobile handsets video products huawei also produces sells variety devices name ideos smartphones tablet pcs huawei smartwatch july 2003 huawei established handset department 2004 huawei shipped first phone c300 u626 huawei first 3g phone june 2005 2006 huawei launched first vodafone-branded 3g handset v710 u8220 huawei first android smartphone unveiled mwc 2009 ces 2012 huawei introduced ascend range starting ascend p1 s. mwc 2012 huawei launched ascend d1 september 2012 huawei launched first 4g ready phone ascend p1 lte ces 2013 huawei launched ascend d2 ascend mate mwc 2013 ascend p2 launched world first lte cat4 smartphone june 2013 huawei launched ascend p6 december 2013 huawei introduced honor subsidiary independent brand china ces 2014 huawei launched ascend mate2 4g 2014 mwc 2014 huawei launched mediapad x1 tablet ascend g6 4g smartphone launched 2014 included ascend p7 may 2014 ascend mate7 ascend g7 ascend p7 sapphire edition china first 4g smartphone sapphire screen january 2015 huawei discontinued ascend brand flagship phones launched new p series huawei p8 huawei also partnered google build nexus 6p 2015 current models p mate lines p30 p30 pro mate 20 mate 20 pro mate 20 x released 2018 2019 emotion ui emui rom/os developed huawei technologies co. ltd. based google android open source project aosp emui pre-installed huawei smartphone devices subsidiaries honor series huawei technologies co. ltd. world largest telecom equipment maker china largest telephone-network equipment maker 3,442 patents huawei became world 1 applicant international patents 2014 21 r institutes countries including china united states canada united kingdom pakistan finland france belgium germany colombia sweden ireland india russia israel turkey huawei considering opening new research development r center russia 2019/2020 would third country moscow st. petersburg r centers huawei also announced plans november 2018 open r center french city grenoble would mainly focused smartphone sensors parallel computing software development new r team grenoble expected grow 30 researchers 2020 said company company said new addition brought five number r teams country two located sophia antipolis paris researching image processing design two existing teams based huawei facilities boulogne-billancourt working algorithms mobile 5g standards technology giant also intended open two new research centers zürich lausanne switzerland huawei time employed around 350 people switzerland huawei faced criticism various aspects operations prominent controversies involved u.s. allegations products containing backdoors chinese government espionage—consistent domestic laws requiring chinese citizens companies cooperate state intelligence warranted huawei executives consistently denied allegations stated company never received requests chinese government introduce backdoors equipment would refuse chinese law compel huawei also accused various instances intellectual property theft parties nortel cisco systems t-mobile us huawei employee photographed robotic arm used stress-test smartphones taken fingertip robot
|
Computer architecture
|
wish unix shell wish windowing shell tcl interpreter extended tk commands available unix-like operating systems x window system macos microsoft windows android provides developers facility create gui widgets using tk toolkit tcl programming language wish open-source currently part tcl/tk programming suite codice_1 run without parameters codice_2 prompt displayed interpreter awaits commands entered interactively user empty window opened widgets created user commands displayed mode suitable experimenting often codice_1 run name file containing tcl/tk script parameter also possible run directly tcl/tk scripts unix using shebang construction windows associating codice_4 extension wish program
|
Operating systems
|
william b black jr. william bolding black jr. born august 25 1936 former deputy director national security agency black joined national security agency 1959 operational linguist/analyst three years army employed nsa black completed wide variety assignments including special assistant director information warfare chief group operations analysis chief nsa/css representative europe office nceur associate deputy director operations/ military support served chief deputy chief major field installation worked way senior cryptologic executive service primary focus building new organizations creating new ways business black retired nsa 1997 1997 black became assistant vice president director information operations advanced technologies solutions group science applications international corporation saic saic black led information operations research worked information operations technology center establish institute analysis complex systems develop advanced techniques analysis networks critical infrastructures black returned nsa 2000 become deputy director since 2002 overseeing trailblazer project aimed analyzing data computer networks tracking cell phone email communications 2002 main contract trailblazer ultimately worth us 1.2 billion awarded black former employer science applications international corporation april 2005 outgoing nsa director michael hayden told senate hearing trailblazer program several hundred million dollars budget years behind schedule michael hayden promotion deputy director national intelligence black acting director nsa appointment new nsa director lt. gen. keith b. alexander august 2006 black replaced john c. inglis offered take position liaison officer nsa british intelligence counterpart native new mexico black currently resides pasadena maryland wife iris three children 1975 mr. black served various positions nsa headquarters nsa european headquarters pentagon
|
Computer security
|
rufus software rufus free open-source portable application microsoft windows used format create bootable usb flash drives live usbs developed pete batard akeo consulting rufus originally designed modern open source replacement hp usb disk storage format tool windows primarily used create dos bootable usb flash drives first official release rufus version 1.0.3 earlier versions internal/alpha released december 11 2011 originally ms-dos support version 1.0.4 introduced freedos support version 1.1.0 introduced iso image support 1.2.0 two separate versions provided one ms-dos one freedos uefi boot support introduced version 1.3.2 localization 1.4.0 windows go 2.0 last version compatible windows xp vista 2.18 rufus supports variety bootable .iso files including various linux distributions windows installation .iso files well raw disk image files including compressed ones needed install bootloader syslinux grub onto flash drive render bootable also allows installation ms-dos freedos onto flash drive well creation windows go bootable media supports formatting flash drives fat fat32 ntfs exfat udf refs filesystems rufus also used compute md5 sha-1 sha-256 hashes currently selected image
|
Operating systems
|
certified information systems security professional certified information systems security professional cissp independent information security certification granted international information system security certification consortium also known isc ² december 31 2018 131,180 isc ² members holding cissp certification worldwide 171 countries united states holding highest member count 84,557 members cissp designation accredited ansi also formally approved u.s. department defense dod information assurance technical iat managerial iam categories dodd 8570 certification requirement mid-1980s need arose standardized vendor-neutral certification program provided structure demonstrated competence november 1988 special interest group computer security sig-cs member data processing management association dpma brought together several organizations interested goal international information systems security certification consortium isc ² formed mid-1989 non-profit organization 1990 first working committee establish common body knowledge cbk formed first version cbk finalized 1992 cissp credential launched 1994 2003 cissp adopted baseline u.s. national security agency issep program cissp curriculum covers subject matter variety information security topics cissp examination based isc ² terms common body knowledge cbk according isc ² cissp cbk taxonomy – collection topics relevant information security professionals around world cissp cbk establishes common framework information security terms principles allow information security professionals worldwide discuss debate resolve matters pertaining profession common understanding 15 april 2018 cissp curriculum updated follows 2015 early 2018 cissp curriculum divided eight domains similar latest curriculum domain changed name security engineering 2018 revision expanded security architecture engineering 2015 covered ten similar domains number cissp members december 31 2018 holders cissp certifications earn additional certifications areas specialty three possibilities standard exam costs 699 usd 650 eur 2019 cissp credential valid three years holders renew submitting continuing professional education cpe credits also yearly membership fee required maintain certification fee increased nearly 50 starting mid-2019 2005 certification magazine surveyed 35,167 professionals 170 countries compensation found cissps led list certificates ranked salary 2006 certification magazine salary survey also ranked cissp credential highly ranked cissp concentration certifications top best-paid credentials 2008 another study came conclusion professionals cissp major security certifications least 5 years experience tend salaries around us us 26 higher professionals similar experience levels certificates note actual cause-and-effect relationship certificate salaries remains unproven 2017 study cybersecuritydegrees.com surveyed 10,000 current historical cyber security job listings preferred candidates holding cissp certifications cybersecuritydegrees found job openings offered average salary average cyber security salary ansi certifies cissp meets requirements ansi/iso/iec standard 17024 personnel certification accreditation program
|
Computer security
|
clamtk clamtk free software graphical interface clamav command line antivirus software program linux desktop users provides on-demand scheduled scanning project started dave mauroni february 2004 remains development clamtk originally written using tk widget toolkit named later re-written perl using gtk toolkit interface evolved considerably time recent versions quite different early releases adding features changing interface presentation dual-licensed gnu general public license version 1 later artistic license clamtk interface allows scanning single files directories configured recursive scans scanning sub-directories whitelists scan potentially unwanted applications puas exclude hidden files large files 20 mb 2017 ghacks reviewer mike turcotte-mccusker noted high rate false positives pua-inclusive scans return history selection allows reviewing results previous scans quarantined files clamtk allows manual automatic updates configured clamav virus definitions application interfaces thunar-sendto-clamtk nemo-sendto-clamtk clamtk-gnome clamtk-kde provide context menu functionality associated file managers thunar nemo gnome files dolphin allowing users directly send files clamtk scanning clamtk also run command-line interface although main reason command line access exists interface various file managers clamtk included repositories many linux distributions including alt linux arch linux centos debian fedora gentoo linux mint mandriva opensuse pclinuxos red hat enterprise linux ubuntu well freebsd users install clamtk repositories linux distribution using application website also provides downloads latest release versions form .rpm .deb files 2014 review clamtk 5.0.7 silviu stahie softpedia recommended application means getting clamav functionality easy-to-use graphical interface wrote basically functions clamtk performed terminal clamav would fine desktop environment like server reason use terminal regular linux distribution 2015 review bill toulas forge noted clamtk seemed take comparable amount time scan clamav indicting n't slowing scanning engine 2017 review linux ubuntu said clamtk provides simple gui allows beginners comfortable use cli upon launching clamtk presented clean gui 4 main sections 2018 listing mangesh dhulap top 10 best free linux antivirus programs – reviewed smart tricks listed clamtk first choice free linux antivirus programs ubuntu pit listing best linux antivirus top 10 reviewed compared clamtk recommended average users described lightweight 2019 review make tech easier included clamtk review best antivirus programs ubuntu reported need good virus scanner ’ fan command line clamtk best choice rewiew derrik diener additive tips 2019 stated ... like features clamav tool dislike dealing command-line ’ get useful features nice easy-to-use interface ... clamtk takes advanced clamav features command-line wraps incredibly simple user interface average linux user use
|
Computer security
|
list cyber attack threat trends list cyber attack threat trends presented alphabetical order methods used 1990s 2015
|
Computer security
|
windows nt processor scheduling windows nt processor scheduling refers process windows nt determines job task run computer processor time without scheduling processor would give attention jobs based arrived queue usually optimal part scheduling processor gives priority level different processes running machine two processes requesting service time processor performs jobs one higher priority six named priority levels levels associated numbers applications start base priority level eight system dynamically adjusts priority level give applications access processor priority levels 0 15 used dynamic applications priority levels 16- 31 reserved real-time applications multiprocessing environment one logical processor i.e multiple cores hyperthreading one task running time however process thread set run subset available logical processors windows task manager utility offers user interface process level
|
Computer architecture
|
european sleep apnea database european sleep apnea database esada also referred spelling european sleep apnoea database european sleep apnoea cohort collaboration european sleep centres part european cooperation science technology cost action b 26 main contractor project sahlgrenska academy gothenburg university institute medicine department internal medicine co-ordinator jan hedner md phd professor sleep medicine book clinical genomics practical applications adult patient care said esada example initiatives afford excellent opportunity future collaborative research genetic aspects obstructive sleep apnea syndrome osas european respiratory society european sleep research society noted impact research cooperative efforts database resource 2006 european sleep apnea database esada began initiative 27 european sleep study facilities combine information compile one shared resource formed part european cooperation science technology cost action b 26 addition financial help cost initiative received assistance companies philips respironics resmed database storing association resource information located gothenburg sweden group goal twofold serve reference guide researching sleep disorders compile information different caregivers treat patients suffering sleep apnea 5,103 patients tracked march 2007 august 2009 data collected patients included symptoms suffered medication medical history sleep data inputted online format analysis database researchers reported methodology results 2010 american thoracic society observed findings regarding percentages metabolic cardiovascular changes related patients obstructive sleep apnea 2010 research resulted collaboration 22 study centres across 16 countries europe involving 27 researchers primary participants presented american thoracic society included researchers sahlgrenska university hospital gothenburg sweden technion – israel institute technology haifa israel national tb lung diseases research institute warsaw poland cnr institute biomedicine molecular palermo italy instituto auxologico italiano ospedale san luca milan italy st. vincent university hospital dublin ireland analysis published 2010 american journal respiratory critical care medicine 2011 22 sleep disorder centres europe involved collaboration group published research 2011 analyzing percentage patients suffering sleep apnea obesity 2012 database maintained information 12,500 patients europe also contained dna samples 2,600 individuals esada represented 2012 21st annual meeting european sleep research society paris france one four european sleep research networks held session event pierre escourrou fadia jilwan wrote 2012 article european respiratory journal studying data esada involving 8,228 total patients 23 different facilities analyzed whether polysomnography good measure hypopnea sleep apnea researchers department pulmonary diseases turku university hospital turku finland compared variations sleep centres esada database published findings european respiratory journal looked traits 5,103 patients 22 centres reported average age patients database prevalence region performing sleep study cardiorespiratory polygraphy database added centre hamburg germany 2013 managed physician holger hein group annual meeting 2013 held edinburgh united kingdom run renata riha march 2013 approximately 13,000 total patients studied program 200 additional patients added database month analysis published researchers italy sweden september 2013 european respiratory journal analyzed correlation renal function problems obstructive sleep apnea analyzed data 17 countries europe representing 24 sleep centres 8,112 total patients tested whether patients different types demographics existing health problems change probability kidney function problems concurrently suffered obstructive sleep apnea 2014 researchers released data studying 5,294 patients database compared prevalence sleep apnea increased blood sugar results published european respiratory journal studied glycated hemoglobin levels patients compared measured severity sleep apnea researchers analyzed glycated hemoglobin levels among class individuals less severe sleep apnea higher determined amount sleep apnea problems 20 march 2014 database included information total 15,956 patients 2014 article european respiratory journal drawing esada analyzed whether lack adequate oxygen night sleep indicator high blood pressure 2013 book clinical genomics practical applications adult patient care esada said example kind initiative affords excellent opportunity future collaborative research genetic aspects obstructive sleep apnea syndrome osas european respiratory society european sleep research society noted impact research cooperative efforts database resource
|
Databases
|
sacred armour antiriad sacred armour antiriad action game published palace software september 1986 amstrad cpc commodore 64 ibm pc compatibles trs-80 zx spectrum north america game published epyx rad warrior original game came 16-page comic book created graphic artist daniel malone game one earliest examples metroidvania genre developed without knowledge concurrently metroid sacred armour antiriad mixture platform maze game player controls tal start simply man dressed loincloth thrown rocks weapon later find legendary antiriad armour wear activate status panel bottom screen shows tal suit strength remaining lives in-game messages among things game-environment full dangerous creatures minions mysterious overlords tal defend hostile beings throwing rocks suit using suits beam-weapon capabilities located installed necessary equipment antiriad armour tal also needs find collect additions armour order allow fly shoot etc tal use suit explore game area occasionally need leave collect power re-charges suit come too-much attack suit destroyed power depleted 2086 civilization destroys nuclear armageddon two factions develop anti-radiation battlesuit completely immune conventional weapons go war diplomatic peace talks break following millennia survivors develop hardy peaceful race living quiet agricultural existence one day mysterious alien forces emerge old volcano containing prewar military base attack quickly conquering enslaving new breed humans forcing populace work mines many rebel mysterious overlords one rebels tal instructed elders seek-out legendary armoured suit sacred armour antiriad last word corruption anti-radiation fact one prewar battlesuits whose development originally instigated diplomatic crisis started nuclear war armour rumoured render wearer impervious attack help tal hopes defeat overthrow alien rulers earth however armour requires equipment added order make function fully include anti-gravity boots particle negator pulsar beam implosion mine last add-on important one needed destroy volcano enemy uses base
|
Computer architecture
|
search/retrieve web service search/retrieve web service srw web service search retrieval srw provides soap interface queries augment url interface provided companion protocol search/retrieve via url sru queries sru srw expressed using contextual query language cql standards srw sru cql promulgated united states library congress
|
Web technology
|
fdupes fdupes program written adrián lópez scan directories duplicate files options list delete replace files hardlinks pointing duplicate first compares file sizes partial md5 signatures full md5 signatures performs byte-by-byte comparison verification fdupes written c released mit license
|
Computer file systems
|
distinguishing attack cryptography distinguishing attack form cryptanalysis data encrypted cipher allows attacker distinguish encrypted data random data modern symmetric-key ciphers specifically designed immune attack words modern encryption schemes pseudorandom permutations designed ciphertext indistinguishability algorithm found distinguish output random faster brute force search considered break cipher similar concept known-key distinguishing attack whereby attacker knows key find structural property cipher transformation plaintext ciphertext random prove cryptographic function safe often compared random oracle function would random oracle attacker able predict output function function distinguishable random oracle non-random properties exists relation different outputs input output used attacker example find part input example let sequence random bits generated random oracle sequence generated pseudo-random bit generator two parties use one encryption system encrypt message length n bitwise xor next n bits respectively output encryption using truly random sequence distinguished output encryption appear random well sequence distinguishable encryption may reveal information m. two systems said indistinguishable exists algorithm connected either able decide whether connected t. distinguishing attack given algorithm d. broadly attack attacker given black box containing either instance system attack unknown key random object domain system aims emulate algorithm able tell whether system random object black box one attack example distinguishing attack stream cipher rc4 might one determines whether given stream bytes random generated rc4 unknown key classic examples distinguishing attack popular stream cipher itsik mantin adi shamir showed 2nd output byte rc4 heavily biased toward zero another example souradyuti paul bart preneel cosic shown xor value 1st 2nd outputs rc4 also non-uniform significantly theoretical biases demonstrable computer simulation
|
Computer security
|
playstation 2 playstation 2 officially abbreviated ps2 home video game console developed marketed sony computer entertainment first released japan march 4 2000 north america october 26 2000 europe australia november 2000 successor playstation well second video game console playstation brand sixth-generation console ps2 competed sega dreamcast nintendo gamecube microsoft xbox announced 1999 ps2 offered backwards compatibility predecessor dualshock controller well games ps2 best-selling video game console time sold 159 million units estimated ign 150 million confirmed sony 2011 3,800 game titles released ps2 since launch 1.5 billion copies sold sony later manufactured several smaller lighter revisions console known slimline models 2004 2006 sony announced launched successor playstation 3 even release successor ps2 remained popular well seventh generation continued produced january 4 2013 sony finally announced discontinued twelve years production – one longest lifespans video game console despite announcement new games console continued produced end 2013 including final fantasy xi seekers adoulin japan fifa 13 north america pro evolution soccer 2014 europe repair services system japan ended september 7 2018 though sony kept details playstation 2 development secret work console began around time original playstation released late 1994 insiders stated developed u.s. west coast former members argonaut software 1997 word leaked press console would backwards compatibility original playstation built-in dvd player internet connectivity sony announced playstation 2 ps2 march 1 1999 video game console positioned competitor sega dreamcast first sixth-generation console released although ultimately main rivals ps2 nintendo gamecube microsoft xbox dreamcast launched successfully north america later year selling 500,000 units within two weeks soon dreamcast north american launch sony unveiled playstation 2 tokyo game show september 20 1999 sony showed fully playable demos upcoming playstation 2 games including gran turismo 2000 later released tekken tag tournament showed console graphic abilities power ps2 launched march 2000 japan october north america november europe sales console games accessories pulled 250 million first day beating 97 million made first day dreamcast directly release difficult find ps2 units retailer shelves due manufacturing delays another option purchasing console online auction websites ebay people paid thousand dollars console ps2 initially sold well partly basis strength playstation brand console backward compatibility selling 980,000 units japan march 5 2000 one day launch allowed ps2 tap large install base established playstation another major selling point competition later sony added new development kits game developers ps2 units consumers ps2 built-in functionality also expanded audience beyond gamer debut pricing less standalone dvd player made console low cost entry home theater market success ps2 end 2000 caused sega problems financially competitively sega announced discontinuation dreamcast march 2001 18 months successful western launch despite dreamcast still received support 2001 ps2 remained sixth generation console eye future 6 months would face competition new rivals form nintendo gamecube microsoft xbox many analysts predicted close three-way matchup among three consoles xbox powerful hardware gamecube least expensive console nintendo changed policy encourage third-party developers playstation 2 theoretically weakest specification three head start due installed base plus strong developer commitment well built-in dvd player xbox required adapter gamecube lacked support entirely playstation 2 initial games lineup considered mediocre changed 2001 holiday season release several blockbuster games maintained ps2 sales momentum held newer rivals sony also countered xbox temporarily securing playstation 2 exclusives highly anticipated games grand theft auto series sony cut price console may 2002 us 299 199 north america making price gamecube 100 less xbox also planned cut price japan around time cut price twice japan 2003 2006 sony cut cost console anticipation release playstation 3 sony unlike sega dreamcast originally placed little emphasis online gaming first years although changed upon launch online-capable xbox coinciding release xbox live sony released playstation network adapter late 2002 several online first–party titles released alongside demonstrate active support internet play sony also advertised heavily online model support electronic arts ea ea offer online xbox titles 2004 although sony nintendo started late although followed decentralized model online gaming responsibility developer provide servers sony moves made online gaming major selling point ps2 september 2004 time launch sony revealed newer slimmer ps2 preparation launch new models scph-700xx-9000x sony stopped making older models scph-3000x-500xx let distribution channel empty stock units apparent manufacturing issue sony reportedly underestimated demand caused initial slowdown producing new unit caused part shortages time old units cleared new units ready issue compounded britain russian oil tanker became stuck suez canal blocking ship china carrying ps2s bound uk one week november british sales totalled 6,000 units compared 70,000 units weeks prior shortages 1,700 stores north america day christmas playstation 2 software distributed cd-rom dvd-rom addition console play audio cds dvd movies backwards compatible playstation games ps2 also supports playstation memory cards controllers although original playstation memory cards work original playstation games controllers may support functions analog buttons ps2 games standard playstation 2 memory card 8 mb capacity variety non-sony manufactured memory cards available playstation 2 allowing memory capacity larger standard 8 mb console also features 2 usb ports 1 ieee 1394 firewire port scph-10000 3900x hard disk drive installed expansion bay back console required play certain games notably popular final fantasy xi available certain models hardware uses emotion engine cpu custom-designed processor based mips architecture floating point performance 6.2 gflops custom-designed graphics synthesizer gpu fillrate 2.4 gigapixels/second capable rendering 75 million polygons per second accounting features lighting texture mapping artificial intelligence game physics real-world performance 3 million 16 million polygons per second playstation 2 may natively output video resolutions sdtv hdtv 480i 480p games gran turismo 4 tourist trophy known support up-scaled 1080i resolution using following standards composite video 480i s-video 480i rgb 480i/p vga progressive scan games ps2 linux component video display original playstation games native 240p mode hdtv sets support d-terminal cables available signal types cables also output analog stereo audio additionally rf modulator available system connect older tvs digital s/pdif audio may also output console via toslink connector outputs 2.0 pcm 5.1 channel sound dolby digital dts formats ps2 undergone many revisions internal construction others involving substantial external changes ps2 primarily differentiated models featuring original fat case design slimline models introduced end 2004 2010 sony bravia kdl-22px300 made available consumers 22 hd-ready television incorporated built-in playstation 2 ps2 standard color matte black several variations color produced different quantities regions including ceramic white light yellow metallic blue aqua metallic silver navy star blue opaque blue astral blue opaque black midnight black pearl white sakura purple satin gold satin silver snow white super red transparent blue ocean blue also limited edition color pink distributed regions oceania parts asia september 2004 sony unveiled third major hardware revision available late october 2004 smaller thinner quieter original versions included built-in ethernet port markets also integrated modem due thinner profile contain 3.5 expansion bay therefore support internal hard disk drive also lacked internal power supply later revision excluding japan version similar gamecube modified multitap expansion removal expansion bay criticized limitation due existence titles final fantasy xi required use hdd sony also manufactured consumer device called psx used digital video recorder dvd burner addition playing ps2 games device released japan december 13 2003 first sony product include xrossmediabar interface sell well japanese market released anywhere else class action lawsuit filed sony computer entertainment america inc. july 16 2002 superior court california county san mateo lawsuit addresses consumer reports inappropriate disc error disc read error messages problems associated playing dvds cds playstation 2 sony settled disc read error lawsuit compensating affected customers us 25 free game specified list reduced cost repair replacement scea discretion damaged system settlement subject courts approval hearings began us canada april 28 2006 may 11 2006 respectively playstation 2 software distributed cd-rom dvd-rom two formats differentiated color discs bottoms cd-roms blue dvd-roms silver playstation 2 offered particularly high-profile exclusive games main entries grand theft auto final fantasy metal gear solid series released exclusively console several prolific series got start playstation 2 including god war ratchet clank jak daxter devil may cry kingdom hearts sly cooper best-selling game console game releases peaked 2004 declined release playstation 3 2006 last new games console final fantasy xi seekers adoulin asia fifa 13 north america pro evolution soccer 2014 europe june 30 2007 total 10,035 software titles released worldwide counting games released multiple regions separate titles playstation 2 users option play select games internet using broadband internet connection playstation 2 network adaptor instead unified subscription-based online service like xbox live competitor microsoft later chose xbox console online multiplayer functionality playstation 2 responsibility game publisher ran third-party servers recent playstation 2 online games developed exclusively support broadband internet access xbox live similarly requires broadband internet connection playstation 2 sold 155 million units worldwide march 31 2013 europe sold 48 million units may 6 2008 according sony computer entertainment europe north america sold 50 million units december 2008 japan ps2 sold 21,454,325 units october 1 2008 according famitsu /enterbrain 2005 playstation 2 became fastest game console reach 100 million units shipped accomplishing feat within 5 years 9 months launch since surpassed playstation 4 playstation 2 dualshock 2 controller largely identical playstation dualshock basic functionality however includes analog pressure sensitivity face shoulder d-pad buttons replacing digital buttons original buttons would later become digital release dualshock 4 like predecessor dualshock 2 controller force feedback vibration functionality lighter includes two levels vibration optional hardware includes additional dualshock dualshock 2 controllers ps2 dvd remote control internal external hard disk drive hdd network adapter horizontal vertical stands playstation ps2 memory cards multitap playstation ps2 usb motion camera eyetoy usb keyboard mouse headset original ps2 multitap scph-10090 plugged newer slim models multitap connects memory card slot well controller slot memory card slot slimline shallower new slim-design multitaps scph-70120 manufactured models however third-party adapters also exist permit original multitaps used early versions ps2 could networked via i.link port though little game support dropped third party manufacturers created devices allow disabled people access ps2 ordinary switches etc third-party companies joytech produced lcd monitor speaker attachments ps2 attach back console allow users play games without access television long access mains electricity similar power source screens fold onto ps2 similar fashion laptop screens many accessories musical games dance pads dance dance revolution groove pump titles konami microphones use karaoke revolution games dual microphones sold used exclusively singstar games various guitar controllers guitar freaks series guitar hero series drum set controller sold box set guitar controller usb microphone use rock band guitar hero series world tour newer taiko drum controller specialized controllers include light guns guncon fishing rod reel controllers slime controller final fantasy x-2 tiny bee dual pistol controller katana controller resident evil 4 chainsaw controller unlike playstation requires use official sony playstation mouse play mouse-compatible games ps2 games mouse support work standard usb mouse well usb trackball addition games also support usage usb keyboard text input game control lieu dualshock dualshock 2 gamepad tandem usb mouse using homebrew programs possible play various audio video file formats ps2 homebrew programs also used play patched backups original ps2 dvd games unmodified consoles install retail discs installed hard drive older models homebrew emulators older computer gaming systems developed ps2 sony released linux-based operating system linux playstation 2 ps2 package also includes keyboard mouse ethernet adapter hdd europe australia ps2 comes free yabasic interpreter bundled demo disc allows users create simple programs ps2 port netbsd project blackrhino gnu/linux alternative debian-based distribution also available ps2
|
Computer architecture
|
freearc freearc free open-source high-performance file archiver developed bulat ziganshin beta version 0.666 released 2010 freearc next version development version fa 0.11 released october 2016. still current version next version supports 32- 64-bit windows linux includes zstandard support current status information released developers since 2016 website offline longer accessible project considered abandoned users sourceforge confirmed sources reddit software archived longer actively developed august 2019 freearc uses lzma prediction partial matching trueaudio tornado grzip algorithms automatic switching file type additionally uses filters improve compression including rep finds repetitions separations 1gb dict dictionary replacements text delta improves compression tables binary data bcj executables preproccesor lzp removes repetitions text 2010 tom hardware benchmarks comparing popular archivers freearc narrowly outperformed winzip 7-zip winrar best compression mode default compression tests lost 7-zip lzma2 still compressed better winrar winzip tom hardware tests freearc outpaced default settings 7zip lzma2 default compression also winrar even best compression settings freearc compression best settings slower 7zip winrar still came ahead winzip metric devised werner bergmans maximum compression benchmark freearc compression efficient programs classic formats like .z lzw .zip deflate .gz bzip2 scoring formula used non-public test multiplies sum compression decompression times factor exponentially grades ratio archive sizes achieved program test relative best known archive size data set november 2010 freearc top program benchmark followed nanozip bsc winrar works faster winrar 7zip like rar zip archiver data compressor like gzip bzip2 initially supported archive format normally identified codice_1 file name extension incompatible others relationship .arc formats recently decompression support archive types added including zip rar 7z freearc command line interface gui features include windows binaries available developer 64-bit variant version 0.666 october 2016 first public release freearc next released currently available cli application 32 64 bit windows linux platforms new features include
|
Computer file systems
|
securelevel securelevel security mechanism *bsd kernels optionally restrict certain capabilities securelevel controlled sysctl variable kern.securelevel value integer set value 0 enables certain class restrictions superuser process raise securelevel init process even freebsd lower used freebsd jails jail maintains securelevel addition global securelevel evaluated higher two securelevels used allows host environment run lower securelevel jails manipulate file flags jails may able compiled options regression new sysctl added freebsd kernel allows securelevel lowered purposes automated regression testing securelevel confused runlevel openbsd securelevels defined follows
|
Operating systems
|
intelligent character recognition computer science intelligent character recognition icr advanced optical character recognition ocr — rather specific — handwriting recognition system allows fonts different styles handwriting learned computer processing improve accuracy recognition levels icr software self-learning system referred neural network automatically updates recognition database new handwriting patterns extends usefulness scanning devices purpose document processing printed character recognition function ocr hand-written matter recognition process involved recognising hand writing accuracy levels may circumstances good achieve 97 accuracy rates reading handwriting structured forms often achieve high recognition rates several read engines used within software given elective voting rights determine true reading characters numeric fields engines designed read numbers take preference alpha fields engines designed read hand written letters higher elective rights used conjunction bespoke interface hub hand-written data automatically populated back office system avoiding laborious manual keying accurate traditional human data entry important development icr invention automated forms processing 1993 joseph corcoran awarded patent invention involved three-stage process capturing image form processed icr preparing enable icr engine give best results capturing information using icr engine finally processing results automatically validate output icr engine application icr increased usefulness technology made applicable use real world forms normal business applications modern software applications use icr technology recognizing text forms filled hand hand-printed intelligent word recognition iwr recognize extract ria printed-handwritten information cursive handwriting well icr recognizes character-level whereas iwr works full words phrases capable capturing unstructured information every day pages iwr said evolved hand print icr meant replace conventional icr ocr systems iwr optimized processing real-world documents contain mostly free-form hard-to-recognize data fields inherently unsuitable icr means highest best use iwr eliminate high percentage manual entry handwritten data run-on hand print fields documents otherwise could keyed humans
|
Computational linguistics
|
alpac alpac automatic language processing advisory committee committee seven scientists led john r. pierce established 1964 united states government order evaluate progress computational linguistics general machine translation particular report issued 1966 gained notoriety skeptical research done machine translation far emphasizing need basic research computational linguistics eventually caused u.s. government reduce funding topic dramatically alpac set april 1964 john r. pierce chairman committee consisted testimony heard alpac final recommendations p. 34 therefore research supported
|
Computational linguistics
|
jmusic jmusic open source music programming library written java programming language written andrew sorensen andrew brown jmusic released publicly november 1998 gnu gpl license designed assist composers music software developers providing support music data structures modifications input/output various file formats display notes sheet music see music notation jmusic data structure based musical score metaphor consists hierarchy notes phrases parts score jmusic also sound synthesis architecture instruments created chain audio objects similar unit generators languages jmusic score rendered jmusic instruments audio file
|
Programming language topics
|
shavlik technologies shavlik technologies privately held company founded 1993 mark shavlik one original developers windows nt late 1980s early 1990s microsoft company provided software services network vulnerability assessment managing network security patches mark shavlik left role ceo shavlik technologies acquired vmware may 2011 held position vice president general manager vmware march 2013 april 2013 landesk purchased shavlik business unit rights shavlik products vmware period landesk announced partnership made vmware alliance partner 2017 landesk merged heat software created new software company called ivanti today shavlik name retired shavlik products vital ivanti security portfolio prior acceptance windows nt legitimate enterprise operating system late 1990s enterprise software written unix mainframe operating system shavlik roots providing consulting services help organizations make leap microsoft os contributed delivering products nt shavlik later extended services business software security consulting primarily businesses highly regulated industries banking healthcare services centered providing certified information systems security professional cissp perform security audits penetration testing early 2000s failure keep software up-to-date applying patches common flag audits one central challenges addressing problem companies easy way determine machines date methodology deploy updates era microsoft wrestled addressing issue internally wanted tool detect nt servers large nt server environment missing patches hot fixes see hotfix could installed machines however nt servers critical operations microsoft required process completed without installing extra software agent servers effort address hot fix issue shavlik built first agentless patch scanner windows nt product named hfnetchk acronym designating hotfix network check hfnetchk release followed another partnership wherein shavlik helped build microsoft baseline security analyzer mbsa tool minimal patch scanning along basic os configuration checks delivered microsoft part windows 2000 server toolkit hfnetchk pro 3.0 never released externally introduced ability scan missing patches also deploy patches eliminated need administrator apply patches manually 2003 shavlik brought hfnetchk market first time version 4 featured visual basic web friendly user interface previous versions hfnetchk operated via command line interface january 2003 sql slammer worm exploited vulnerability sql server allowed denial service slowed traffic many internet hosts crawl worm went viral affecting 75,000 systems first ten minutes microsoft made patch available six months prior indicating failure patch led widespread security breach vulnerability shavlik hfnetchk first product market could scan deploy missing patches windows machines aftermath sql slammer worm series highly publicized exploits hit 2003/2004 shavlik made decision move away consulting fully invest software development patch management products shavlik added standalone integrated anti-virus capabilities version 5 hfnetchk changed product name hfnetchk protect eventually dropping hfnetchk version 6 timeframe protect introduced capability patch offline virtual machines vm templates project first series partnerships shavlik entered vmware capability meant protect could agentlessly patch machines physical virtual environments version 7 various point releases new user interface introduced well physical virtual asset inventory agent support integrated protect longer offered separately licensed product shavlik also shifted detection logic protect content version 8 protect fixed many stability issues due number customer complaints shavlik focused making product stable version 9 introduced hypervisor patching vmware implementations well ability patch off-network machines via cloud shavlik technological advancements significant enough attract attention microsoft resulting cooperative efforts two companies development microsoft baseline security analyzer mbsa based shavlik hfnetchk acronym designating hotfix network checker released 2001 technology evolved still core technology current product offerings licensed multiple oem partners provide patch management capabilities variety management solutions combined install base millions users across globe late 2000s industry saw applications exploited hackers shift microsoft os microsoft applications third-party applications like java adobe music players non-microsoft internet browsers time products like microsoft system center configuration manager sccm provided windows patch capabilities via windows server update services wsus however n't still n't patch third-party products according global analyst firm gartner left administrators limited choices n't patch third-party products leaving network risk author test custom patch time third-party product requires update deploy patches manually affected machine april 2010 shavlik released scupdates – catalog patch content automated process building third-party patches delivering windows clients via integration microsoft system center updates publisher scup sccm tandem initial scupdates release microsoft shavlik also announced shavlik inclusion microsoft system center alliance 2010 shavlik released it.shavlik provided web-based front-end traditional shavlik toolkit asset inventory patch scanning patch deployment software service saas application simplified workflow inventory systems patching possible on-premises protect solution early 2009 shavlik formed oem partnership vmware build cloud-based application designed help administrators smaller businesses deploy virtual environment vmware go vgo intended onramp virtualization serving smaller customers ready upgrade sophisticated vcenter suite vgo originally brought market free-use cloud-based product vmware shavlik invested heavily vgo product expanded include asset inventory patch scanning advisor recommendation engine later attempts monetize vgo services paid version called vmware go pro introduced patch deployment led migration users it.shavlik vmware go vmware interest vgo well virtual infrastructure patching capabilities within protect led acquisition shavlik technologies may 2011 terms acquisition publicly disclosed january 2013 vmware announced intent sharpen focus software-defined data center hybrid cloud services part realignment vmware sought sell products n't contributing core business sliderocket presentation software non-key cloud virtualization technologies shavlik product line found list april 2013 landesk software purchased shavlik business unit rights shavlik products vmware time landesk announced partnership added vmware landesk list alliance partners shavlik move landesk triggered new investment shavlik patch microsoft system center formerly scupdates well products enhance experience companies using sccm early 2017 clearlake capital group acquired landesk shavlik along heat software appsense wavelink combined company uses new corporate name product brand ivanti
|
Computer security
|
chargeware chargeware seemingly valid looking mobile applications used charge user services without proper notification knowledge often focused internet pornography third-party porn apps downloaded onto user mobile device turn infecting phone malware known chargeware purpose chargeware manipulate user agreeing unclear terms fees charges applied without user full understanding consent chargeware deliberately difficult renege charges continue long possible without carrier interference 2013 hundreds thousands users primarily france uk experienced applications nature ultimately lead forms malware mobile device various countries spain encountered chargeware infections almost matched number adware infections japan lowest number chargeware infections country hackers reportedly learning market changing tactics i.e. mobile malware operations harder trace harder shut said markets also include specific countries since charging practices vary either country carrier basis
|
Computer security
|
essentials programming languages essentials programming languages eopl textbook programming languages daniel p. friedman mitchell wand christopher t. haynes eopl surveys principles programming languages operational perspective starts interpreter scheme simple functional core language similar lambda calculus systematically adds constructs addition example variable assignment thread-like control book illustrates increase expressive power programming language demand new constructs formulation direct interpreter book also demonstrates systematic transformations say store-passing style continuation-passing style eliminate certain constructs language interpreter formulated second part book dedicated systematic translation interpreter register machines transformations show eliminate higher-order closures continuation objects recursive function calls end reader left interpreter uses nothing tail-recursive function calls assignment statements plus conditionals becomes trivial translate code c program even assembly program bonus book shows pre-compute certain pieces meaning generate representation pre-computations since essence compilation book also prepares reader course principles compilation language translation related distinct topic apart text explaining key concepts book also comprises series exercises enabling readers explore alternative designs issues like sicp eopl represents significant departure prevailing textbook approach 1980s time book principles programming languages presented four six even programming languages discussed programming idioms implementation high level successful books typically covered algol 60 so-called algol family programming languages snobol lisp prolog even today fair number textbooks programming languages surveys though scope narrowed eopl started 1983 indiana one leading departments programming languages research eugene kohlbecker one friedman phd students transcribed collected 311 lectures faculty members including mitch wand christopher haynes started contributing turned hitchhiker guide meta-universe —as kohlbecker called it—into systematic interpreter transformation-based survey 25 years existence book become near-classic third edition including additional topics types modules first part incorporates ideas programming htdp another unconventional textbook uses scheme teach principles program design authors well matthew flatt recently provided drracket plug-ins language levels teaching eopl eopl spawned least two related texts queinnec lisp small pieces krishnamurthi
|
Programming language topics
|
network computer reference profile network computer reference profile nc reference profile ncrp specification network computer put forward oracle corporation endorsed sun microsystems ibm apple computer netscape finalized 1996 first version specification known nc1 reference profile ncrp specified minimum hardware requirements software protocols among software requirements support ip-based protocols tcp/ip ftp etc www standards http html java email protocols multimedia file formats security standards operating systems used ncos javaos minimum hardware requirements although initial nc standard intended promote diskless workstation model computing preclude computers additional features ability operate either diskless workstation conventional fat client thus ordinary personal computer pc required features could technically classified network computer indeed sun noted contemporary pcs indeed meet nc reference requirements reference profile subsequently revised use strongarm processor trip ellison acer group headquarters 1996 realised importance industry products based intel x86-compatible processors nci president jerry baker noted nobody corporate users ever heard arm chip many ncs operated via protocols bootp dhcp rarp nfs isp-bound lan-based reference implementation ncs smartcard option available allowed user authentication performed secure manner ssl providing transport security smartcard also provided minimal local storage isp dialup configuration settings configuration data required lan-based ncs network computer brand created oracle ncrp specification
|
Computer architecture
|
relation database relational database theory relation originally defined e. f. codd set tuples ... element member data domain codd original definition notwithstanding contrary usual definition mathematics ordering elements tuples relation instead element termed attribute value attribute name paired domain nowadays commonly referred type data type attribute value attribute name paired element attribute domain tuple set attribute values two distinct elements name thus accounts tuple described function mapping names values set attributes two distinct elements name called heading set tuples heading called body relation thus heading paired body heading relation also heading tuple body number attributes constituting heading called degree term also applies tuples relations term n -tuple refers tuple degree n n ≥ 0 e. f. codd used term relation mathematical sense finitary relation set tuples set n sets ... thus n -ary relation interpreted closed world assumption extension n -adic predicate n -tuples whose values substituted corresponding free variables predicate yield propositions hold true appear relation term relation schema refers heading paired set constraints defined terms heading relation thus seen instantiation relation schema heading schema satisfies applicable constraints sometimes relation schema taken include name relational database definition database schema sometimes referred relational schema thus thought collection named relation schemas implementations domain attribute effectively data type named relation schema effectively relation variable relvar short sql database language relational databases relations represented tables row table represents single tuple values attribute form column example relation three named attributes 'id domain integers 'name 'address domain strings predicate relation using attribute names denote free variables might employee number id known name lives address examination relation tells us four tuples predicate holds true example employee 102 known name yonezawa akinori live anywhere else naha okinawa also apart four employees shown employee name address definition body tuples body appear particular order one say tuple 'murata makoto tuple 'matsumoto yukihiro one say tuple 'yonezawa akinori first tuple similar comment applies rows sql table definition heading attributes element appear particular order either therefore elements tuple similar comment apply sql define ordering columns table relational database consists named relation variables relvars purposes updating database response changes real world update single relvar causes body relation assigned variable replaced different set tuples relvars classified two classes base relation variables derived relation variables latter also known virtual relvars usually referred short term view base relation variable relation variable derived relation variables sql term base table equates approximately base relation variable view defined expression using operators relational algebra relational calculus expression operates one relations evaluated yields another relation result sometimes referred derived relation operands relations assigned database variables view defined giving name expression name subsequently used variable name note expression must mention least one base relation variable using data definition language ddl able define base relation variables sql codice_1 syntax used define base tables following example data definition language ddl also used define derived relation variables sql codice_2 syntax used define derived relation variable following example
|
Databases
|
ultra 1 ultra 1 family sun microsystems workstations based 64-bit ultrasparc microprocessor first model sun ultra series sun computers succeeded sparcstation series launched 1995 shipped solaris 2.5 capable running operating systems linux bsd ultra 1 available variety different specifications three different cpu speeds available 143 mhz model 140 167 mhz model 170 200 mhz model 200 ultra 1 creator3d 170e launched november 1995 list price us 27,995 model numbers e suffix sun service code a12 internal codename electron two instead three sbus slots added upa slot allow use optional creator framebuffer addition e models wide scsi fast ethernet interfaces place narrow scsi 10base-t ethernet standard ultra 1 service code a11 codename neutron ultra 1 uses 200-pin 5v ecc 60ns simm pairs similar sun machines netra 1 servers chassis ultraserver 1/ultra enterprise 1 servers
|
Computer architecture
|
blasteroids blasteroids third official sequel 1979 shoot 'em video game asteroids developed atari games released coin-operated game 1987 unlike previous games blasteroids uses raster graphics vector graphics home computer ports blasteroids released image works amiga amstrad cpc atari st commodore 64 msx ms-dos zx spectrum additionally though appeared midway arcade compilation prior emulated version blasteroids included lego dimensions unlockable mini-game gameplay game basically original player players case 2-player game controls spaceship viewed 2d representation space rotating ship using thrust give ship momentum slow completely stop moving player rotate ship face direction came generate right amount thrust nullify momentum ship limited amount fuel generate thrust fuel comes form energy also used ship shields protect collisions enemy fire energy gone player ship destroyed ship shoot destroy asteroids enemy ships ship also transformed 3 different versions namely speeder fastest version fighter firepower warrior extra armour start game player screen four warps indicating game difficulty easy medium hard expert flying warps starts game difficulty several galaxies 9 16 sectors depending difficulty sector completed destroying asteroids exit portal appears lead player galactic map screen similarly difficulty screen player choose sector visit next completed empty sectors revisited costs energy sectors currently range marked sector consists visible screen wraparound object game destroy asteroids set speed fly sector asteroids come varying sizes shot larger asteroids break multiple smaller ones shooting smallest ones actually remove sector asteroids also come different types normal asteroids n't contain anything red asteroids contain power-ups form power crystals released completely destroying asteroids crystals decay time popcorn asteroids require several hits expands size eventually makes stop spinning ca n't destroyed stopping enough finish sector egg asteroids contain leeches home user ship suck energy shot destroyed finally seeker asteroids home player ship shot besides asteroids different enemy ships trying shoot player leave equipment form power-ups destroyed different kinds equipment mukor alien boss sectors cleared asteroids try ram player send miniature enemy ships aid mukor tentacles must shot multiple times destroyed tentacles gone mukor defeated leave special equipment reappear next galaxy larger number tentacles making harder defeat mukor must defeated galaxies fully conquered player win game second player join game time pressing fire button using 1 credit turning blasteroids multiplayer game players cooperate covering well docking ships starlet docking possible one ship speeder warrior flying turn speeder stationary turret firepower top warrior turns spiaret less firepower full control ships undock either player transforms ship something else first player exit exit portal gets large bonus control galactic map
|
Computer architecture
|
wired equivalent privacy wired equivalent privacy wep security algorithm ieee 802.11 wireless networks introduced part original 802.11 standard ratified 1997 intention provide data confidentiality comparable traditional wired network wep recognizable key 10 26 hexadecimal digits 40 104 bits one time widely use often first security choice presented users router configuration tools 2003 wi-fi alliance announced wep superseded wi-fi protected access wpa 2004 ratification full 802.11i standard i.e wpa2 ieee declared wep-40 wep-104 deprecated wep encryption protocol available 802.11a 802.11b devices built wpa standard available 802.11g devices however 802.11b devices later provided firmware software updates enable wpa newer devices built wep ratified wi-fi security standard 1999 first versions wep particularly strong even time released u.s. restrictions export various cryptographic technology led manufacturers restricting devices 64-bit encryption restrictions lifted increased 128-bit despite introduction 256-bit wep 128-bit remains one common implementations wep included privacy component original ieee 802.11 standard ratified 1997 wep uses stream cipher rc4 confidentiality crc-32 checksum integrity deprecated 2004 documented current standard standard 64-bit wep uses 40 bit key also known wep-40 concatenated 24-bit initialization vector iv form rc4 key time original wep standard drafted u.s. government export restrictions cryptographic technology limited key size restrictions lifted manufacturers access points implemented extended 128-bit wep protocol using 104-bit key size wep-104 64-bit wep key usually entered string 10 hexadecimal base 16 characters 0–9 a–f character represents 4 bits 10 digits 4 bits gives 40 bits adding 24-bit iv produces complete 64-bit wep key 4 bits × 10 24 bits iv 64 bits wep key devices also allow user enter key 5 ascii characters 0–9 a–z a–z turned 8 bits using character byte value ascii 8 bits × 5 24 bits iv 64 bits wep key however restricts byte printable ascii character small fraction possible byte values greatly reducing space possible keys 128-bit wep key usually entered string 26 hexadecimal characters 26 digits 4 bits gives 104 bits adding 24-bit iv produces complete 128-bit wep key 4 bits × 26 24 bits iv 128 bits wep key devices also allow user enter 13 ascii characters 8 bits × 13 24 bits iv 128 bits wep key 152-bit 256-bit wep systems available vendors wep variants 24 bits iv leaving 128 232 bits actual protection 128 232 bits typically entered 32 58 hexadecimal characters 4 bits × 32 24 bits iv 152 bits wep key 4 bits × 58 24 bits iv 256 bits wep key devices also allow user enter 16 29 ascii characters 8 bits × 16 24 bits iv 152 bits wep key 8 bits × 29 24 bits iv 256 bits wep key two methods authentication used wep open system authentication shared key authentication open system authentication wlan client provide credentials access point authentication client authenticate access point attempt associate effect authentication occurs subsequently wep keys used encrypting data frames point client must correct keys shared key authentication wep key used authentication four-step challenge-response handshake authentication association pre-shared wep key also used encrypting data frames using rc4 first glance might seem though shared key authentication secure open system authentication since latter offers real authentication however quite reverse possible derive keystream used handshake capturing challenge frames shared key authentication therefore data easily intercepted decrypted shared key authentication open system authentication privacy primary concern advisable use open system authentication wep authentication rather shared key authentication however also means wlan client connect ap authentication mechanisms weak shared key wep deprecated favor wpa/wpa2 rc4 stream cipher traffic key must never used twice purpose iv transmitted plain text prevent repetition 24-bit iv long enough ensure busy network way iv used also opened wep related key attack 24-bit iv 50 probability iv repeat 5000 packets august 2001 scott fluhrer itsik mantin adi shamir published cryptanalysis wep exploits way rc4 ciphers iv used wep resulting passive attack recover rc4 key eavesdropping network depending amount network traffic thus number packets available inspection successful key recovery could take little one minute insufficient number packets sent ways attacker send packets network thereby stimulate reply packets inspected find key attack soon implemented automated tools since released possible perform attack personal computer off-the-shelf hardware freely available software aircrack-ng crack wep key minutes cam-winget et al surveyed variety shortcomings wep write experiments field show proper equipment practical eavesdrop wep-protected networks distances mile target also reported two generic weaknesses 2005 group u.s. federal bureau investigation gave demonstration cracked wep-protected network 3 minutes using publicly available tools andreas klein presented another analysis rc4 stream cipher klein showed correlations rc4 keystream key ones found fluhrer mantin shamir additionally used break wep wep-like usage modes 2006 bittau handley lackey showed 802.11 protocol used wep enable earlier attacks previously thought impractical eavesdropping single packet attacker rapidly bootstrap able transmit arbitrary data eavesdropped packet decrypted one byte time transmitting 128 packets per byte decrypt discover local network ip addresses finally 802.11 network connected internet attacker use 802.11 fragmentation replay eavesdropped packets crafting new ip header onto access point used decrypt packets relay buddy internet allowing real-time decryption wep traffic within minute eavesdropping first packet 2007 erik tews andrei pychkine ralf-philipp weinmann able extend klein 2005 attack optimize usage wep new attack possible recover 104-bit wep key probability 50 using 40,000 captured packets 60,000 available data packets success probability 80 85,000 data packets 95 using active techniques like deauth arp re-injection 40,000 packets captured less one minute good conditions actual computation takes 3 seconds 3 mb main memory pentium-m 1.7 ghz additionally optimized devices slower cpus attack used 40-bit keys even higher success probability 2008 payment card industry pci security standards council latest update data security standard dss prohibits use wep part credit-card processing 30 june 2010 prohibits new system installed uses wep 31 march 2009 use wep contributed tj maxx parent company network invasion use encrypted tunneling protocols e.g ipsec secure shell provide secure data transmission insecure network however replacements wep developed goal restoring security wireless network recommended solution wep security problems switch wpa2 wpa intermediate solution hardware could support wpa2 wpa wpa2 much secure wep add support wpa wpa2 old wi-fi access points might need replaced firmware upgraded wpa designed interim software-implementable solution wep could forestall immediate deployment new hardware however tkip basis wpa reached end designed lifetime partially broken officially deprecated release 802.11-2012 standard stopgap enhancement wep present early 802.11i drafts implementable hardware able handle wpa wpa2 extended iv key values 128 bits hoped eliminate duplicate iv deficiency well stop brute force key attacks became clear overall wep algorithm deficient iv key sizes would require even fixes wep2 name original algorithm dropped two extended key lengths remained eventually became wpa tkip wepplus also known wep+ proprietary enhancement wep agere systems formerly subsidiary lucent technologies enhances wep security avoiding weak ivs completely effective wepplus used ends wireless connection easily enforced remains serious limitation also necessarily prevent replay attacks ineffective later statistical attacks rely weak ivs dynamic wep refers combination 802.1x technology extensible authentication protocol dynamic wep changes wep keys dynamically vendor-specific feature provided several vendors 3com dynamic change idea made 802.11i part tkip actual wep algorithm
|
Computer security
|
modern combat sandstorm modern combat sandstorm 2009 first-person shooter developed published gameloft ios webos bada android first game modern combat series followed 2010 2011 2012 2014 game set middle east sandstorm plays similarly game features ten missions varied environments different tasks players complete main enemies game terrorists often player accompanied soldiers fight alongside movement controlled virtual joystick screen sight aim controlled scrolling across touchscreen players also crouch throw grenades use iron sights reload change weapons shoot using virtual buttons touchscreen controls customized main menu online multiplayer ability added sandstorm free update january 28 2010 chief warrant officer mike chief warrens returns injury active duty war terrorism middle east reunites old squad dozer ryan fox captain jones completing training run chief joins squad head destroy terrorist radio outpost successfully completing mission await evacuation disused hotel extraction helicopter shot forced defend hotel safely extracted humvee mission squad notice terrorists seemed ready coming conclusion someone leaking information sent hospital capture abu bahaa terrorist warlord chief dozer infiltrate hospital sewer system ryan jones wait outside reaching bahaa room chief discovers tricked hospital rigged explosives dummy placed bahaa hospital bed chief dozer manage escape unscathed outside jones injured ryan killed jones recovers squad break dockyard bahaa using store large nuclear weapon discover terrorists enormous base underground entrance hidden within metal freight container chief sent find nuke encounters bahaa inside forced allow escape locate bomb could detonated terrorists minute eventually finds able secure bahaa flees attempts escape truck squad pursue humvee chasing dockyard train tunnel eventually flipping truck reaches highway squad find bahaa lying truck still alive dozer prepares secure however jones betrays squad killing dozer taking fox hostage bahaa taunts chief saying weak choice surrender chief shoots jones falls ground fox bahaa pulls two grenades jacket prepares blow chief fox pulls ground tells chief run chief takes cover humvee bahaa fox killed explosion chief subsequently promoted becomes hero returning us travels fox residence meets wife informing husband act martyrdom saved life variety weapons modern combat sandstorm range two assault rifles one higher rate fire movement speed lacking power accuracy comparison smg shotgun sniper rifle rpg weapons found stored crates often inside side building along path indicated missions weapons include m16a3 mp5a2 m870 ak-47 m24 sws m249 rpg-7 high-definition version game released april 1 2010 ipad features updated controls graphics make use ipad larger screen upon release sandstorm received extremely positive reviews ios version holds aggregate score 83 gamerankings based seven reviews ign mark bozon scored 8.5 10 calling game pushes system gamers would expect possible ... sandstorm nice blending power manageable touch controls ends way game 'd expect find mere 6.99 ... 're willing put little time learning controls sandstorm impressive shooter proof iphone handle fps gaming 148apps equally impressed scoring 4 5 praising graphics modern combat features impressive 3d graphics iphone best graphics best period textures surprisingly detailed character models great annoying pop-up however less impressed gameplay mission structure simply linear map narrow little choice movement blatant green arrows also guide preventing hope exploration appspy dave flodine scored game 5 5 believing set new bar first person shooters idevices modern combat sandstorm mold future fpss iphone cast game without issues offering workable control scheme superb presentation solid play length could n't ask better title satisfy iphone fps cravings pocket gamer jon jordan similarly impressed scoring game 8 10 giving silver award especially impressed control schemes really clever way gameloft shaped gameplay modern combat sandstorm turn limitations iphone comes first person shooters notably touch controls game strength slide play chris reed scored game 4 4 also believing game set new standard idevices gaming experience modern combat sandstorm great one controls best 've seen iphone fps graphics beautiful plenty level variety sure 've seen idevice never small price like first-person shooters buy game eli hodapp toucharcade scored game 4 5 expressing similar sentiments pocket gamer slide play modern combat sandstorm excellent game raises bar expected future first person shooters iphone well added short list games fantastic on-screen controls ... 're interested shooters looking great game flex muscles iphone look modern combat sandstorm touchgen matt dunn slightly less impressed reviewers scored game 3.5 5 critical ai really n't much way ai modern combat story story modern combat bland best generic terrorist driven plot descent twist end game makes attempt suck connect squad-mates hard really care ... dialogue storyline feel like written someone knows little armed forces wrote story based war games 've played praised graphics textures crisp look great close gun models reloading/first-person character animations awesome controls everything feels accessible logical
|
Operating systems
|
vectra ai vectra ai inc. applies artificial intelligence detects responds hidden cyberattackers inside cloud data center enterprise networks company ’ cognito platform designed detect cyberattacker behaviors infrastructures allow security analysts conduct incident investigations hunt hidden threats using security-enriched metadata augment cognito platform vectra threat researchers identify investigate cyberattacks vulnerabilities malicious behaviors unknown world data sets research data scientists develop machine learning algorithms behavioral analysis drive cognito platform investors vectra include khosla ventures tcv accel partners ia ventures ame cloud ventures dag ventures wipro ventures atlantic bridge ireland strategic investment fund nissho electronics silver lake vectra founded 2010 tracevector llc new york city incorporated 2012 name vectra networks company headquartered san jose calif. facilities austin texas cambridge mass. switzerland germany ireland united kingdom france vectra ’ team includes threat researchers white hats data scientists security engineers user interface designers key executives hitesh sheth president chief executive officer oliver tavakoli chief technology officer howie shohet chief financial officer kevin moore senior vice president worldwide field operations didi dayton vice president worldwide channels alliances jennifer wang vice president customer success mike banic vice president marketing kevin kennedy vice president product management jason kehl vice president engineering aaron bean vice president human resources gerard bauer vice president emea sales board members include hitesh sheth president ceo vectra kevin dillon co-founder managing partner atlantic bridge charles giancarlo ceo pure storage brad gillespie general partner ia ventures jim messina founder ceo messina group bruce armstrong operating partner kholsa ventures eric wolford venture partner accel partners cognito platform vectra provides continuous automated threat surveillance expose hidden unknown cyberattackers actively spread inside networks cognito analyzes network traffic private data centers public clouds enterprise environments detect hidden cyberattacker behaviors cognito platform identifies prioritizes threat detections based severity certainty scores empowers security teams prevent data loss quickly mitigating serious attacks first threat behaviors cyberattack techniques detected cognito include botnet command-and-control communications botnet monetization internal reconnaissance lateral movement data theft exfiltration vectra offers three applications cognito platform address use cases using ai incident detection triage security operations center helped one vectra customer – texas university system – resolve incident 10 20 minutes rather hours days vectra ai combines data science machine learning network behavioral analysis technologies identify patterns characterize malicious behavior within network cognito uses artificial intelligence including supervised learning unsupervised machine learning deep learning techniques detect respond advanced cyberattacks remediation actions taken security information event management siems firewalls endpoint security enforcement network access control orchestration integrated cognito via application programming interface vectra issued ten u.s. patents advanced cyber security analytics capabilities automated ai vectra publishes attacker behavior industry reports provide analysis active persistent attacker behaviors inside enterprise networks vectra customers reports examine wide range cyberattack detections trends 300+ vectra customersfrom nine different industries reports span strategic phases attack lifecycle vectra customers received industry recognition including
|
Computer security
|
wi-fi protected access wi-fi protected access wpa wi-fi protected access ii wpa2 wi-fi protected access 3 wpa3 three security protocols security certification programs developed wi-fi alliance secure wireless computer networks alliance defined response serious weaknesses researchers found previous system wired equivalent privacy wep wpa sometimes referred draft ieee 802.11i standard became available 2003 wi-fi alliance intended intermediate measure anticipation availability secure complex wpa2 became available 2004 common shorthand full ieee 802.11i ieee 802.11i-2004 standard january 2018 wi-fi alliance announced release wpa3 several security improvements wpa2 wi-fi alliance intended wpa intermediate measure take place wep pending availability full ieee 802.11i standard wpa could implemented firmware upgrades wireless network interface cards designed wep began shipping far back 1999 however since changes required wireless access points aps extensive needed network cards pre-2003 aps could upgraded support wpa wpa protocol implements much ieee 802.11i standard specifically temporal key integrity protocol tkip adopted wpa wep used 64-bit 128-bit encryption key must manually entered wireless access points devices change tkip employs per-packet key meaning dynamically generates new 128-bit key packet thus prevents types attacks compromised wep wpa also includes message integrity check designed prevent attacker altering resending data packets replaces cyclic redundancy check crc used wep standard crc main flaw provide sufficiently strong data integrity guarantee packets handled well tested message authentication codes existed solve problems required much computation used old network cards wpa uses message integrity check algorithm called tkip verify integrity packets tkip much stronger crc strong algorithm used wpa2 researchers since discovered flaw wpa relied older weaknesses wep limitations message integrity code hash function named michael retrieve keystream short packets use re-injection spoofing wpa2 replaced wpa wpa2 requires testing certification wi-fi alliance implements mandatory elements ieee 802.11i particular includes mandatory support ccmp aes-based encryption mode certification began september 2004 march 13 2006 wpa2 certification mandatory new devices bear wi-fi trademark january 2018 wi-fi alliance announced wpa3 replacement wpa2 new standard uses 128-bit encryption wpa3-personal mode 192-bit wpa3-enterprise forward secrecy wpa3 standard also replaces pre-shared key exchange simultaneous authentication equals defined ieee 802.11-2016 resulting secure initial key exchange personal mode wi-fi alliance also claims wpa3 mitigate security issues posed weak passwords simplify process setting devices display interface wpa designed specifically work wireless hardware produced prior introduction wpa protocol provides inadequate security wep devices support wpa applying firmware upgrades available legacy devices wi-fi devices certified since 2006 support wpa wpa2 security protocols wpa2 may work older network cards different wpa versions protection mechanisms distinguished based target end-user according method authentication key distribution encryption protocol used originally eap-tls extensible authentication protocol transport layer security certified wi-fi alliance april 2010 wi-fi alliance announced inclusion additional eap types wpa- wpa2- enterprise certification programs ensure wpa-enterprise certified products interoperate one another 802.1x clients servers developed specific firms may support eap types certification attempt popular eap types interoperate failure one major issues preventing rollout 802.1x heterogeneous networks commercial 802.1x servers include microsoft internet authentication service juniper networks steelbelted radius well aradial radius server freeradius open source 802.1x server pre-shared key wpa wpa2 remain vulnerable password cracking attacks users rely weak password passphrase wpa passphrase hashes seeded ssid name length rainbow tables exist top 1,000 network ssids multitude common passwords requiring quick lookup speed cracking wpa-psk brute forcing simple passwords attempted using aircrack suite starting four-way authentication handshake exchanged association periodic re-authentication wpa3 replaces cryptographic protocols susceptible off-line analysis protocols require interaction infrastructure guessed password supposedly placing temporal limits number guesses however design flaws wpa3 enables attackers plausibly launch brute-force attacks see dragonblood attack wpa wpa2 n't provide forward secrecy meaning adverse person discovers pre-shared key potentially decrypt packets encrypted using psk transmitted future even past could passively silently collected attacker also means attacker silently capture decrypt others packets wpa-protected access point provided free charge public place password usually shared anyone place words wpa protects attackers n't access password safer use transport layer security tls similar top transfer sensitive data however starting wpa3 issue addressed mathy vanhoef frank piessens significantly improved upon wpa-tkip attacks erik tews martin beck demonstrated inject arbitrary amount packets packet containing 112 bytes payload demonstrated implementing port scanner executed client using wpa-tkip additionally showed decrypt arbitrary packets sent client mentioned used hijack tcp connection allowing attacker inject malicious javascript victim visits website contrast beck-tews attack could decrypt short packets mostly known content arp messages allowed injection 3 7 packets 28 bytes beck-tews attack also requires quality service defined 802.11e enabled vanhoef-piessens attack neither attack leads recovery shared session key client access point authors say using short rekeying interval prevent attacks strongly recommend switching tkip aes-based ccmp halvorsen others show modify beck-tews attack allow injection 3 7 packets size 596 bytes downside attack requires substantially time execute approximately 18 minutes 25 seconds work vanhoef piessens showed wpa used encrypt broadcast packets original attack also executed important extension substantially networks use wpa protect broadcast packets protect unicast packets execution time attack average around 7 minutes compared 14 minutes original vanhoef-piessens beck-tews attack vulnerabilities tkip significant wpa-tkip held extremely safe combination indeed wpa-tkip still configuration option upon wide variety wireless routing devices provided many hardware vendors survey 2013 showed 71 still allow usage tkip 19 exclusively support tkip serious security flaw revealed december 2011 stefan viehböck affects wireless routers wi-fi protected setup wps feature regardless encryption method use recent models feature enable default many consumer wi-fi device manufacturers taken steps eliminate potential weak passphrase choices promoting alternative methods automatically generating distributing strong keys users add new wireless adapter appliance network methods include pushing buttons devices entering 8-digit pin wi-fi alliance standardized methods wi-fi protected setup however pin feature widely implemented introduced major new security flaw flaw allows remote attacker recover wps pin router wpa/wpa2 password hours users urged turn wps feature although may possible router models also pin written label wi-fi routers wps changed compromised wpa3 introduces new alternative configuration devices lack sufficient user interface capabilities allowing nearby devices serve adequate ui network provisioning purposes thus mitigating need wps several weaknesses found ms-chapv2 severely reduce complexity brute-force attacks making feasible modern hardware 2012 complexity breaking ms-chapv2 reduced breaking single des key work moxie marlinspike marsh ray moxie advised enterprises depending mutual authentication properties ms-chapv2 connection wpa2 radius servers immediately start migrating something else tunneled eap methods using ttls peap encrypt mschapv2 exchange widely deployed protect exploitation vulnerability however prevalent wpa2 client implementations early 2000s prone misconfiguration end users cases e.g android lacked user-accessible way properly configure validation aaa server certificate cns extended relevance original weakness mschapv2 within mitm attack scenarios stricter wpa2 compliance tests announce alongside wpa3 certified client software required conform certain behaviors surrounding aaa certificate validation hole196 vulnerability wpa2 protocol abuses shared group temporal key gtk used conduct man-in-the-middle denial-of-service attacks however assumes attacker already authenticated access point thus possession gtk 2016 shown wpa wpa2 standards contain insecure expository random number generator rng researchers showed vendors implement proposed rng attacker able predict group key gtk supposed randomly generated access point ap additionally showed possession gtk enables attacker inject traffic network allowed attacker decrypt internet traffic transmitted wireless network demonstrated attack asus rt-ac51u router uses mediatek out-of-tree drivers generate gtk showed gtk recovered within two minutes less similarly demonstrated keys generated broadcom access daemons running vxworks 5 later recovered four minutes less affects example certain versions linksys wrt54g certain apple airport extreme models vendors defend attack using secure rng hostapd running linux kernels vulnerable attack thus routers running typical openwrt lede installations exhibit issue october 2017 details krack key reinstallation attack attack wpa2 published krack attack believed affect variants wpa wpa2 however security implications vary implementations depending upon individual developers interpreted poorly specified part standard software patches resolve vulnerability available devices april 2019 serious design flaws wpa3 found allow attackers perform downgrade attacks side-channel attacks enabling brute-forcing passphrase well launching denial-of-service attacks wi-fi base stations
|
Computer security
|
segmentation fault computing segmentation fault often shortened segfault access violation fault failure condition raised hardware memory protection notifying operating system os software attempted access restricted area memory memory access violation standard x86 computers form general protection fault os kernel response usually perform corrective action generally passing fault offending process sending process signal processes cases install custom signal handler allowing recover otherwise os default signal handler used generally causing abnormal termination process program crash sometimes core dump segmentation faults common class error programs written languages like c provide low-level memory access arise primarily due errors use pointers virtual memory addressing particularly illegal access another type memory access error bus error also various causes today much rarer occur primarily due incorrect physical memory addressing due misaligned memory access – memory references hardware address rather references process allowed address many programming languages may employ mechanisms designed avoid segmentation faults improve memory safety example rust programming language appeared 2010 employs 'ownership based model ensure memory safety garbage collection employed since around 1960 avoids certain classes memory errors could lead segmentation faults segmentation fault occurs program attempts access memory location allowed access attempts access memory location way allowed example attempting write read-only location overwrite part operating system term segmentation various uses computing context segmentation fault term used since 1950s refers address space program memory protection program address space readable stack read-write portion data segment program writable read-only data code segment writable thus attempting read outside program address space writing read-only segment address space results segmentation fault hence name systems using hardware memory segmentation provide virtual memory segmentation fault occurs hardware detects attempt refer non-existent segment refer location outside bounds segment refer location fashion allowed permissions granted segment systems using paging invalid page fault generally leads segmentation fault segmentation faults page faults faults raised virtual memory management system segmentation faults also occur independently page faults illegal access valid page segmentation fault invalid page fault segmentation faults occur middle page hence page fault example buffer overflow stays within page illegally overwrites memory hardware level fault initially raised memory management unit mmu illegal access referenced memory exists part memory protection feature invalid page fault referenced memory exist problem invalid logical address instead invalid physical address bus error raised instead though always distinguished operating system level fault caught signal passed offending process activating process handler signal different operating systems different signal names indicate segmentation fault occurred unix-like operating systems signal called sigsegv abbreviated segmentation violation sent offending process microsoft windows offending process receives status_access_violation exception conditions segmentation violations occur manifest specific hardware operating system different hardware raises different faults given conditions different operating systems convert different signals passed processes proximate cause memory access violation underlying cause generally software bug sort determining root cause – debugging bug – simple cases program consistently cause segmentation fault e.g. dereferencing null pointer cases bug difficult reproduce depend memory allocation run e.g. dereferencing dangling pointer following typical causes segmentation fault turn often caused programming errors result invalid memory access c code segmentation faults often occur errors pointer use particularly c dynamic memory allocation dereferencing null pointer always result segmentation fault wild pointers dangling pointers point memory may may exist may may readable writable thus result transient bugs example dereferencing variables could cause segmentation fault dereferencing null pointer generally cause segfault reading wild pointer may instead result random data segfault reading dangling pointer may result valid data random data overwritten default action segmentation fault bus error abnormal termination process triggered core file may generated aid debugging platform-dependent actions may also performed example linux systems using grsecurity patch may log sigsegv signals order monitor possible intrusion attempts using buffer overflows writing read-only memory raises segmentation fault level code errors occurs program writes part code segment read-only portion data segment loaded os read-only memory example ansi c code generally cause segmentation fault platforms memory protection attempts modify string literal undefined behavior according ansi c standard compilers catch compile time instead compile executable code crash program containing code compiled string hello world placed rodata section program executable file read-only section data segment loaded operating system places strings constant data read-only segment memory executed variable set point string location attempt made write h character variable memory causing segmentation fault compiling program compiler check assignment read-only locations compile time running unix-like operating system produces following runtime error backtrace core file gdb code corrected using array instead character pointer allocates memory stack initializes value string literal even though string literals modified undefined behavior c standard c codice_1 type implicit conversion original code points codice_2 array c++ codice_3 type thus implicit conversion compilers generally catch particular error c c-like languages null pointers used mean pointer object error indicator dereferencing null pointer read write null pointer common program error c standard say null pointer pointer memory address 0 though may case practice operating systems map null pointer address accessing causes segmentation fault behavior guaranteed c standard dereferencing null pointer undefined behavior c conforming implementation allowed assume pointer dereferenced null sample code creates null pointer tries access value read value causes segmentation fault runtime many operating systems dereferencing null pointer assigning writing value non-existent target also usually causes segmentation fault following code includes null pointer dereference compiled often result segmentation fault value unused thus dereference often optimized away dead code elimination another example recursion without base case causes stack overflow results segmentation fault infinite recursion may necessarily result stack overflow depending language optimizations performed compiler exact structure code case behavior unreachable code return statement undefined compiler eliminate use tail call optimization might result stack usage optimizations could include translating recursion iteration given structure example function would result program running forever probably overflowing stack
|
Operating systems
|
lightweight access point protocol lightweight access point protocol lwapp name protocol control multiple wi-fi wireless access points reduce amount time spent configuring monitoring troubleshooting large network system also allow network administrators closely analyze network system installed central server gathers data rf devices different brands settings server command selected group devices apply given settings simultaneously lwapp proposed airespace standard protocol provide interoperability among brand access point airespace purchased cisco systems purpose standardize lightweight access points internet engineering task force ietf approved standard sponsored cisco systems submitted ietf rfc 5412 although protocol far popular beyond airespace/cisco product lines capwap standard based lwapp support lwapp also found analysis products airmagnet implemented software based protocol analyze cisco wireless products still considered proprietary lwapp systems compete non-standard lightweight wireless mechanisms companies like meru networks aruba networks layer 2 lwapp requires data link connection order transfer frames layer 2 broadcasts even ip connectivity established still operate layer 2 layer 4 udp 12222 data channel 12223 control channel connectivity must established work form protocol broadcasts dhcp option 43 used prime access-points network controller must subnet dhcp configured handle layer 3 lwapp provisioning another option directing ap controller defining controller dns server network
|
Internet protocols
|
bancstar programming language bancstar specialist computer programming language financial applications language internal language national financial computer services inc later broadway seymour bancstar application software automate operations bank branch language fixed format four integer command language nfcs internally referred screen code resembles esoteric programming language much sometimes mistaken joke language conceptually bancstar application executed screen code much like primitive virtual machine 5.1c release legal characters numerals 0–9 comma minus sign carriage return however used real commercial applications originally intended generated code user interface-building tool — similar bytecode rendered ascii — due limitations tool became directly programmed language bancstar 10.0 release changed screen code format binary rearranged numeric codes opcode variable number parameter integers 10.0 opcode encoded bit mapped length value indicated length command words
|
Programming language topics
|
iphone 11 iphone 11 series upcoming smartphones designed developed marketed apple rumoured released september 10 2019 steve jobs theater apple park cupertino apple ceo tim cook may go sale september 21 2019 phone unique among iphones details regarding phone widely leaked august 2019 weeks phone release thirteenth-generation flagships iphone successors iphone xs xr phone criticized due small improvements predecessors mainly camera quality reported phone also keep notch design featured iphone x
|
Operating systems
|
atx atx advanced technology extended motherboard power supply configuration specification developed intel 1995 improve previous de facto standards like design first major change desktop computer enclosure motherboard power supply design many years improving standardization interchangeability parts specification defines key mechanical dimensions mounting point i/o panel power connector interfaces computer case motherboard power supply atx common motherboard design standards smaller boards including microatx flexatx nano-itx mini-itx usually keep basic rear layout reduce size board number expansion slots dimensions full-size atx board allows many atx chassis also accept microatx boards official atx specifications released intel 1995 revised numerous times since recent atx motherboard specification version 2.2 recent atx12v power supply unit specification 2.4 released april 2013 eatx extended atx bigger version atx motherboard 12 x 13 inch dimensions advantages eatx motherboard dual socket support 2004 intel announced btx balanced technology extended standard intended replacement atx atx design still remains popular btx introduced manufacturers back computer case major changes made standard originally style cases keyboard connector expansion slots add-on card backplates onboard interfaces serial parallel ports connected via flying leads connectors mounted either spaces provided case brackets placed unused expansion slot positions atx allowed motherboard manufacturer put ports rectangular area back system arrangement could define though number general patterns depending ports motherboard offers followed manufacturers cases usually fitted snap-out panel also known i/o plate i/o shield one common arrangements necessary i/o plates replaced suit motherboard fitted i/o plates usually included motherboards designed particular computer computer operate correctly without plate fitted although open gaps case may compromise emi/rfi screening allow ingress dirt random foreign bodies panels made allowed fitting motherboard atx case atx motherboards come integrated i/o plate atx also made ps/2-style mini-din keyboard mouse connectors ubiquitous systems used 5-pin din connector keyboard generally used serial port mice although ps/2 mouse ports also found systems many modern motherboards phasing ps/2-style keyboard mouse connectors favor modern universal serial bus legacy connectors slowly phased modern atx motherboards include 25-pin parallel ports 9-pin rs-232 serial ports place onboard peripheral ports ethernet firewire esata audio ports analog s/pdif video analog d-sub dvi hdmi displayport extra usb ports wi-fi several atx-derived designs specified use power supply mountings basic back panel arrangement set different standards size board number expansion slots standard atx provides seven slots spacing popular microatx size removes three slots leaving four width refers distance along external connector edge depth front rear note larger size inherits previous smaller colors area note aopen conflated term mini atx recent design since references mini atx removed atx specifications since adoption microatx aopen definition contemporary term one listed apparently historical significance number manufacturers added one two three additional expansion slots standard 0.8 inch spacing standard 12-inch atx motherboard width form factors considered obsolete 1999 included baby-at full size semi-proprietary lpx low-profile cases proprietary motherboard designs compaq packard-bell hewlett packard others existed interchangeable multi-manufacturer boards cases portable notebook computers custom motherboards unique particular products although true e-atx motherboard manufacturers also refer motherboards measurements e-atx e-atx ssi eeb server system infrastructure ssi forum enterprise electronics bay eeb share dimensions screw holes two standards align rendering incompatible 2008 foxconn unveiled foxconn f1 motherboard prototype width standard atx motherboard extended 14.4 length accommodate 10 slots firm called new design motherboard ultra atx ces 2008 showing also unveiled january 2008 ces lian li armorsuit pc-p80 case 10 slots designed motherboard name xl-atx used least three companies different ways september 2009 evga corporation already released xl-atx motherboard evga x58 classified 4-way sli gigabyte technology launched another xl-atx motherboard model number ga-x58a-ud9 2010 measuring ga-x79-ud7 2011 measuring april 2010 gigabyte announced ga-890fxa-ud7 motherboard allowed seven slots moved downward one slot position added length could allowed placement eight expansion slots top slot position vacant particular model msi released msi x58 big bang 2010 msi p67 big bang marshal 2011 msi x79 xpower big bang 2 2012 msi z87 xpower 2013 although boards room additional expansion slots 9 8 total respectively three provide seven expansion connectors topmost positions left vacant provide room cpu chipset associated cooling 2010 evga corporation released new motherboard super record 2 sr-2 whose size surpasses evga x58 classified 4-way sli new board designed accommodate two dual qpi lga1366 socket cpus e.g intel xeon similar intel skulltrail motherboard could accommodate two intel core 2 quad processors total seven pci-e slots 12 ddr3 ram slots new design dubbed hptx atx specification requires power supply produce three main outputs +3.3 v +5 v +12 v. low-power −12 v +5 v standby supplies also required −12 v supply primarily used provide negative supply voltage rs-232 ports also used one pin conventional pci slots primarily provide reference voltage models sound cards 5 v supply used produce trickle power provide soft-power feature atx pc turned well powering real-time clock conserve charge cmos battery −5 v output originally required supplied isa bus removed later versions atx standard became obsolete removal isa bus expansion slots isa bus still found computer compatible old ibm pc specification e.g. found playstation 4 originally motherboard powered one 20-pin connector atx power supply provides number peripheral power connectors modern systems two connectors motherboard 8-pin 4+4-pin auxiliary connector providing additional power cpu main 24-pin power supply connector extension original 20-pin version 20-pin molex 39-29-9202 motherboard 20-pin molex 39-01-2200 cable connector pin pitch 4.2 mm one sixth inch four wires special functions generally supply voltages must within ±5 nominal values times little-used negative supply voltages however ±10 tolerance specification ripple 10 hz–20 mhz bandwidth 20–24-pin molex mini-fit jr. power rating 600 volts 8 amperes maximum per pin using 18 awg wire large server motherboards 3d graphics cards required progressively power operate necessary revise extend standard beyond original 20-pin connector allow current using multiple additional pins parallel low circuit voltage restriction power flow connector pin maximum rated voltage single mini-fit jr pin would capable 4800 watts atx power supplies generally dimensions width height preceding lpx low profile extension form factor often incorrectly referred power supplies due ubiquitous use later baby systems even though actual power supply form factor physically larger share common mounting layout four screws arranged back side unit last dimension 140 mm depth frequently varied depths 160 180 200 230 mm used accommodate higher power larger fan and/or modular connectors original cases flat case style integrated power switch protruded power supply sits flush hole chassis utilizes paddle-style dpst switch similar pc pc-xt style power supplies later so-called baby lpx style computer cases power button directly connected system computer power supply psu general configuration double-pole latching mains voltage switch four pins connected wires four-core cable wires either soldered power button making difficult replace power supply failed blade receptacles used atx power supply typically controlled electronic switch connected power button computer case allows computer turned operating system addition many atx power supplies equivalent-function manual switch back also ensures power sent components switch power supply turned however computer turned front power button power supply connection motherboard changed older lpx standards lpx two similar connectors could accidentally interchanged forcing different keyed connectors place usually causing short-circuits irreversible damage motherboard rule thumb safe operation connect side-by-side connectors black wires together atx uses one large keyed connector connected incorrectly new connector also provides 3.3 volt source removing need motherboards derive voltage 5 v rail motherboards particularly manufactured introduction atx lpx equipment still use support lpx atx psus using atx psu purposes powering atx motherboard power fully turned always partly operate wake-up devices shorting power-on pin atx connector pin 16 green wire black wire ground power button atx system minimum load one voltages may required varies model vendor standard specify operation without minimum load conforming psu may shut output incorrect voltages otherwise malfunction hazardous damaged atx power supply replacement current-limited bench laboratory dc power supply instead better described bulk dc power supply original atx specification called power supply located near cpu power supply fan drawing cooling air outside chassis directing onto processor thought configuration cooling processor would achievable without need active heatsink recommendation removed later specifications modern atx power supplies usually exhaust air case atx introduced late 1995 defined three types power connectors power distribution specification defined psu power provided 5 v 3.3 v rails electronic components cpu ram chipset pci agp isa cards used 5 v 3.3 v power supply 12 v rail used computer fans motors peripheral devices hdd fdd cd-rom etc designing pentium 4 platform 1999/2000 standard 20-pin atx power connector found insufficient meet increasing power-line requirements standard significantly revised atx12v 1.0 atx12v 1.x sometimes inaccurately called atx-p4 atx12v 1.x also adopted amd athlon xp athlon 64 systems however early model athlon xp mp boards including server boards later model lower-end motherboards 4-pin connector described numbering atx revisions may little confusing atx refers design goes version 2.2 2004 24 pins atx12v 2.0 atx12v describes psu instance atx 2.03 pretty commonly seen psu 2000 2001 often include p4 12v connector even norm define yet main changes additions atx12v 1.0 released february 2000 formally called +12 v power connector commonly referred p4 connector first needed support pentium 4 processor pentium 4 processors generally powered 5 v rail later processors operate much lower voltages typically around 1 v draw 100 infeasible provide power low voltages high currents standard system power supply pentium 4 established practice generating dc-to-dc converter motherboard next processor powered 4-pin 12 v connector minor revision august 2000 power 3.3 v rail slightly increased smaller changes made relatively minor revision january 2002 significant change −5 v rail longer required became optional voltage required isa bus longer present almost modern computers introduced april 2003 month 2.0 standard introduced changes mostly minor atx12v 2.x brought significant design change regarding power distribution analyzing power demands then-current pcs determined would much cheaper practical power pc components 12 v rails instead 3.3 v 5 v rails particular pci express expansion cards take much power 12 v rail 5.5 older agp graphics cards took 1 12 v 6 3.3 v. cpu also driven 12 v rail done 5 v rail older pcs pentium 4 power demands pci express incorporated atx12v 2.0 introduced february 2003 defined quite different power distribution atx12v 1.x minor revision june 2004 errant reference −5 v rail removed minor changes introduced minor revision march 2005 power slightly increased rails efficiency requirements changed also released march 2005 includes corrections specifies high current series wire terminals 24-pin atx motherboard 4-pin +12 v power connectors effective march 2007 recommended efficiency increased 80 least 70 required 12 v minimum load requirement lowered higher efficiency generally results less power consumption less waste heat 80 recommendation brings supplies line new energy star 4.0 mandates reduced load requirement allows compatibility processors draw little power startup absolute over-current limit 240 va per rail removed allowing 12 v lines provide 20 per rail revision became effective february 2008 added maximum allowed ripple/noise specification 400 millivolts pwr_on pwr_ok signals requires dc power must hold 1 millisecond pwr_ok signal drops clarified country-specific input line harmonic content electromagnetic compatibility requirements added section climate savers updated recommended power supply configuration charts updated cross-regulation graphs unofficial name given later revisions v2.31 spec current version atx12v spec published april 2013 specified revision 1.31 'design guide desktop platform form factors names atx12v version 2.4 sfx merely design small form factor sff power supply casing power specifications almost identical atx thus sfx power supply mostly pin-compatible atx power supply main difference reduced dimensions electrical difference sfx specifications require −5 v rail since −5 v required isa-bus expansion cards issue modern hardware decreases productions costs result atx pin 20 carried −5 v absent current power supplies optional atx atx12v version 1.2 deleted atx version 1.3 sfx dimensions 125 × 63.5 × 100 mm width × height × depth 60 mm fan compared standard atx dimensions 150 × 86 × 140 mm optional 80 40 mm fan replacement increases decreases height sfx unit manufacturers retailers incorrectly market sfx power supplies µatx microatx power supplies besides manufacturers make sfx-l dimensions 125 × 63.5 × 130 mm accommodate 120 mm fan thin form factor another small power supply design standard atx specification connectors generally dimensioned w × h × 85 × 64 × 175 mm 3.34 × 2.52 × 6.89 provides wtx style motherboard connector incompatible standard atx motherboard connector atx12v power supply derivative made amd power athlon mp dual processor platform used high-end athlon mp motherboards special 8-pin supplemental connector motherboard amd ges psu required motherboards motherboards work atx 12 v psus a. atx12v-ges 24-pin p1 motherboard connector pinout motherboard connector follows viewing motherboard b. atx12v-ges 8-pin p2 motherboard connector pinout motherboard connector follows viewing motherboard eps12v defined server system infrastructure ssi used primarily smp/multi-core systems core 2 core i7 opteron xeon 24-pin atx motherboard connector atx12v v2.x 8-pin secondary connector optional 4-pin tertiary connector rather include extra cable many power supply makers implement 8-pin connector two combinable 4-pin connectors ensure backwards compatibility atx12v motherboards high-performance video card power demands dramatically increased 2000s high-end graphics cards power demands exceed agp pcie slot capabilities cards supplementary power delivered standard 4-pin peripheral floppy power connector midrange high-end pcie graphics cards manufactured 2004 typically use standard 6 8-pin pcie power connector directly psu although atx power supply specifications mostly vertically compatible ways electrically physically potential issues mixing old motherboards/systems new psus vice versa main issues consider following practical guidance mix mix proprietary brand-name systems require matching proprietary power supply may also support standard interchangeable power supplies efficiency power supplies means extent power wasted converting electricity household supply regulated dc computer power supplies vary around 70 90 efficiency various initiatives exist improve efficiency computer power supplies climate savers computing initiative promotes energy saving reduction greenhouse gas emissions encouraging development use efficient power supplies 80 plus certifies variety efficiency levels power supplies encourages use via financial incentives efficient power supplies also save money wasting less power result use less electricity power computer emit less waste heat results significant energy savings central air conditioning summer gains using efficient power supply substantial computers use lot power although power supply larger needed power rating extra margin safety overloading unit often less efficient wastes electricity lower loads appropriately sized unit example 900-watt power supply 80 plus silver efficiency rating means power supply designed least 85-percent efficient loads 180 w may 73 efficient load lower 100 w typical idle power desktop computer thus 100 w load losses supply would 37 w power supply put 450 w load supply efficiency peaks 89 loss would 56 w despite supplying 4.5 times useful power comparison 500-watt power supply carrying 80 plus bronze efficiency rating means power supply designed least 82-percent efficient loads 100 w may provide 84-percent efficiency 100 w load wasting 19 w
|
Computer architecture
|
criticism microsoft windows various versions microsoft desktop operating system windows received many criticisms since microsoft inception 2010 google engineer tavis ormandy criticized microsoft taking long patch fix reported security vulnerability windows virtual dos machine vdm patched 7 months mr. ormandy reported microsoft 2004 marc maiffret chief hacking officer security research firm eeye digital security criticized microsoft providing security patch windows asn.1 implementation 200 days right release windows vista computer scientist peter gutmann criticised digital rights management drm included microsoft windows allow content providers place restrictions certain types multimedia playback collected criticism write-up released stated analysis drew responses microsoft microsoft states criticized drm features already present windows xp thus new problem customers problematic features would activated required content played responses came george ou zdnet ed bott zdnet ed bott also published three-part rebuttal peter gutmann claims details number factual errors analysis criticizes gutmann reliance questionable sources personal blog postings friends anecdotal evidence google searches analysis paper gutmann never tested theories windows 7 allegations also made draconian drm spurred debate criticism website slashdot claims overreaching vista drm independent tech writers quickly dismissed claims faulty analysis actual problem spurred criticism turned unrelated problem experienced single user tried circumvent adobe creative suite copy protection mechanisms changing files failed work user concluded draconian drm windows windows criticized internet explorer web browser integrated windows shell windows 98 onwards previously internet explorer shipped separate application one problem since explorer easily replaced product another vendor undermines consumer choice issue precipitated concerns microsoft engages monopolistic practices resulted united states v. microsoft corp. court case eventually settled court another issue integration security vulnerabilities internet explorer also create security vulnerabilities windows could allow attacker exploit windows remote code execution january 2009 european commission started investigate microsoft bundling internet explorer windows commission stated microsoft tying internet explorer windows operating system harms competition web browsers undermines product innovation ultimately reduces consumer choice european commission microsoft eventually agreed microsoft would include web browser choice selection screen windows users european economic area means browserchoice.eu google microsoft competitor criticized windows becoming slower less reliable long term use adrian kingsley-hughes writing zdnet believes slow-down time due loading much software loading duplicate software installing much free/trial/beta software using old outdated incorrect drivers installing new drivers without uninstalling old ones may also due malware spyware 1999 andrew fernandez chief scientist cryptonym morrisville north carolina found cryptographic public key stored variable _key second key labeled nsakey discovery lead flurry speculation conspiracy theories second key could owned united states national security agency nsa could allow intelligence agency subvert windows user security also researcher dr. nicko van someren discovered cryptographic keys third key codice_1 file time existed windows 2000 release concerns raised cpus encrypted instruction sets existed time would made impossible discover cryptographic keys microsoft denied allegations — microsoft attributes naming key due technical review nsa pointing backup key required conform regulations evidence name key ever presented key enabled backdoor cryptographer computer security specialist bruce schneier also argued conspiracy theory pointing nsa wanted back door windows microsoft consent would need cryptographic key cryptographic keys included versions windows windows 95 osr2 onwards concerns shown advocates critics windows 10 privacy policies collection use customer data default express settings windows 10 configured send various information microsoft parties including collection user contacts calendar data associated input data personalize speech typing inking input typing inking data improve recognition allow apps use unique advertising id analytics advertising personalization functionality introduced windows 8.1 allow apps request user location data send data microsoft trusted partners improve location detection windows 8 similar settings except location data collection include trusted partners users opt data collection telemetry data error reporting usage also sent microsoft disabled non-enterprise versions windows 10 use cortana intelligent personal assistant also requires collection data device location data calendar apps use data emails text messages call contacts often interact device ” personalize functionality rock paper shotgun writer alec meer argued microsoft intent data collection lacked transparency stating world 45 pages policy documents opt-out settings split across 13 different settings screens external website constitutes 'real transparency extremetech pointed whilst previously campaigning google similar data collection strategies microsoft hoovers data ways would make google jealous however also pointed requirement vast usage customer data become norm citing increased reliance cloud computing forms external processing well similar data collection requirements services mobile devices google siri august 2015 russian politician nikolai levichev called windows 10 banned use russian government sends user data servers united states federal law requiring online services store data russian users servers within country blocked taken effect september 2016 following release 10 allegations also surfaced microsoft backported operating system increased data collection windows 7 windows 8 via recommended patches added additional telemetry features updates addition diagnostics tracking service connected specifically microsoft existing customer experience improvement program opt-in program sends additional diagnostic information microsoft addressing issues application insights service third-party software data collection functionality capable transmitting personal information browsing history contents emails chat video calls voice mail photos documents personal files keystrokes microsoft analysis accordance end user license agreement terms services agreement microsoft updated state following
|
Operating systems
|
xak art visual stage xak art visual stage features typical high fantasy setting according game world legends great war fought benevolent weakening ancient gods demon race led collapse eventual mortality gods 'war sealing gods divided world three parts xak world humans oceanity world faeries xexis world demons demon world xexis tightly sealed two worlds prevent reentry warmongering demon race demons left behind xak however others managed discover separate means enter xak xexis anyway ancient history displayed introduction one badu powerful demon able use coercive magic make humans bidding duel god war managed defeat badu seal away mountain ice 250 years god later settled village known fearless live rest mortal life beginning game badu prison broken demons overrun parts xak order stop ravaging lands king wavis sends messenger faerie dork kart famous warrior living village fearless dork however gone missing player takes role latok kart dork 16-year-old son meets messenger faerie pixie latok embarks king quest slay badu hoping find father along way travels latok guided duel spirit course game turns dork thus latok descendant duel latok playable character game notable non-player characters latok meets include initial versions xak art visual stage released nec pc-8801 pc-9801 systems june 1989 followed graphically distinct releases msx2 november 1989 sharp x68000 april 1990 1992 game released pc engine along sequel one-disc compilation xak ii ported riot game features animated cut scenes requires super system card update played pc engine original cd-rom add-on another console port published sunsoft super famicom february 1993 latest visually enhanced remake developed japanese mobile phones became available vodafone live june 1 2004 game first release bandai rpg empire line role-playing games 2001–2008 pc-8801 msx2 x68000 pc-9801 versions art visual stage made downloadable microsoft windows d4 enterprise project egg online service first official english translation game also released dutch msx games distributor woomb.net early 2007 although website shut 2008 content transferred english counterpart project egg musical score xak art visual stage composed ryuji sasai tadahiro nitta marking first collaboration two musicians game soundtrack comprises 42 tracks released may 5 1989 title sounds xak art visual stage 2007 2008 music game pc-8801 msx2 x68000 versions added catalog d4 enterprise video game music service egg music site offers psg fm variation msx2 tracks use fm sound source extensive music x68000 game praised storyline music xak art visual stage referred micro cabin breakthrough title website famitsū magazine described game ’ story magnificent jayson napolitano original sound version stated music great stuff fans distinct sound late 80s audio art visual stage regarded higher quality games time also noted use visual representation system gave impression depth three-dimensionality
|
Computer architecture
|
oracle database oracle database commonly referred oracle rdbms simply oracle proprietary multi-model database management system produced marketed oracle corporation database commonly used running online transaction processing oltp data warehousing dw mixed oltp dw database workloads latest generation oracle database 19c available on-prem on-cloud hybrid-cloud environment 19c may also deployed oracle engineered systems e.g exadata on-prem oracle public cloud private cloud customer openworld 2017 san francisco executive chairman board cto larry ellison announced next database generation oracle autonomous database larry ellison two friends former co-workers bob miner ed oates started consultancy called software development laboratories sdl 1977 sdl developed original version oracle software name oracle comes code-name cia-funded project ellison worked formerly employed ampex oracle products follow custom release-numbering -naming convention c current release oracle database 19c stands cloud previous releases e.g oracle database 10g oracle9i database used suffixes g stand grid internet respectively prior release oracle8i database suffixes featured oracle database naming conventions note v1 oracle database larry ellison knew one would want buy version 1 oracle rdbms release numbering used following codes oracle database administrators guide includes brief history key innovations introduced major release oracle database oracle corporation releases critical patch updates cpus security patch updates spus security alerts close security holes could used data theft critical patch updates cpus security alerts come quarterly tuesday closest 17th day month oracle database may licensed deployed on-premises choice platforms including oracle engineered systems on-cloud choice services running general purpose hardware exadata various editions cloud services provide different levels database functionality different use cases e.g dev/test departmental non-critical apps mission-critical workloads different levels performance availability etc service levels oracle corporation provides range database cloud services oracle cloud platform designed different database use cases test/dev deployments small medium sized workloads large mission-critical workloads oracle database cloud services available choice general purpose hardware exadata engineered systems either virtual machines environments 'bare metal infrastructure known oracle cloud infrastructure latest oracle database version 12.2.0.1 comes three editions on-premises deployments oracle corporation also makes following edition available including oracle database 12c release 12.1.0.1 oracle also offered following oracle corporation discontinued se se1 12.1.0.2 release stopped offering new licenses editions december 1 2015 oracle database 12 c supported following os architecture combinations 2008 oracle corporation announced availability oracle exadata database machine v1 first generation engineered systems specifically designed oracle database workloads 2011 oracle corporation announced availability oracle database appliance pre-built pre-tuned highly available clustered database server built using two sunfire x86 servers direct attached storage oracle enterprise edition databases running certain oracle-supplied hardware use hybrid columnar compression efficient storage oracle database offers wide range options features areas availability scalability analytics performance security management developers integration aim enhance complement existing database functionality meet customer-specific requirements database options available enterprise edition offered extra cost exception two rules oracle real application clusters option comes included oracle database 12 c standard edition 2 additional cost availability scalability analytics performance security management developers integration apart clearly defined database options oracle databases may include many semi-autonomous software sub-systems oracle corporation sometimes refers features sense subtly different normal use word example oracle data guard counts officially feature command-stack within sql*plus though usability feature appear list features oracle list features may include example oracle database provides long list supported data models used managed inside oracle database oracle corporation classifies utilities bundled software supporting data transfer data maintenance database administration utilities included oracle database distributions include oracle corporation started drive toward wizard -driven environments view enabling non-programmers produce simple data-driven applications popular application development tool ships oracle database oracle application express apex browser-based tool allows developers build responsive database-driven applications leveraging sql pl/sql skills oracle sql developer free graphical tool database development allows developers browse database objects run sql statements sql scripts edit debug pl/sql statements incorporates standard customized reporting oracle rest data services ords function java ee-based alternative oracle http server providing rest-based interface relational data users also develop applications java pl/sql optionally using tools database upgrade assistant dbua provides gui upgrading oracle database jaccelerator ncomp – native-compilation java accelerator integrates hardware-optimized java code oracle 10g database oracle opatch provides patch management oracle databases sqltxplain tool sqlt offers tuning assistance oracle sql queries oracle database accessed many programming languages environments include java based languages like scala use jdbc access oracle database pl/sql routines within oracle databases access external routines registered operating-system shared libraries dbms_scheduler package invoke external scripts operating-system level pl/sql users oracle support contracts use oracle oracle support mos web site – known metalink re-branding exercise completed october 2010 support site provides users oracle corporation products repository reported problems diagnostic scripts solutions also integrates provision support tools patches upgrades remote diagnostic agent rda operate command-line diagnostic tool executing script data captured provides overview oracle database environment intended diagnostic trouble-shooting within rda hcve health check validation engine verify isolate host system environmental issues may affect performance oracle software oracle corporation also endorses certain practices conventions enhancing use database products include oracle certification program professional certification program includes administration oracle databases one main certification paths contains three levels large number user groups oracle database administrators developers users established geographical/region industry product basis including oracle user group communities also host regular events customers/users share experiences knowledge 2016 oracle holds 1 rdbms market share worldwide based revenue share ahead four closest competitors – microsoft ibm sap teradata market relational databases oracle database competes commercial products ibm db2 udb microsoft sql server oracle ibm tend battle mid-range database market unix linux platforms microsoft dominates mid-range database market microsoft windows platforms however since share many customers oracle ibm tend support products many middleware application categories example websphere peoplesoft siebel systems crm ibm hardware divisions work closely oracle performance-optimizing server-technologies example linux z systems niche commercial competitors include teradata data warehousing business intelligence software ag adabas sybase ibm informix among many others increasingly oracle database products compete open-source software relational database systems postgresql mongodb couchbase oracle acquired innobase supplier innodb codebase mysql part compete better open source alternatives acquired sun microsystems owner mysql 2010 database products licensed open source legal terms open source definition free distribute free royalty licensing fees oracle database system—identified alphanumeric system identifier sid—comprises least one instance application along data storage instance—identified persistently instantiation number activation id sys.v_ database.activation —comprises set operating-system processes memory-structures interact storage typical processes include pmon process monitor smon system monitor oracle documentation refer active database instance shared memory realm users oracle databases refer server-side memory-structure sga system global area sga typically holds cache information data-buffers sql commands user information addition storage database consists online redo logs logs hold transactional history processes turn archive online redo logs archive logs offline redo logs provide basis data recovery physical-standby forms data replication using oracle data guard oracle rac real application clusters option uses multiple instances attached central storage array version 10 g grid computing introduced shared resources instance use cpu resources another node grid advantage oracle rac resources nodes used database node uses memory cpu information shared nodes interconnect—the virtual private network oracle dbms store execute stored procedures functions within pl/sql oracle corporation proprietary procedural extension sql object-oriented language java invoke code objects and/or provide programming structures writing oracle rdbms stores data logically form tablespaces physically form data files datafiles tablespaces contain various types memory segments data segments index segments etc segments turn comprise one extents extents comprise groups contiguous data blocks data blocks form basic units data storage dba impose maximum quotas storage per user within tablespace partitioning feature introduced oracle 8 allows partitioning tables based different set keys specific partitions added dropped help manage large data sets oracle database management tracks computer data storage help information stored codice_1 tablespace codice_1 tablespace contains data dictionary indexes clusters data dictionary consists special collection tables contains information user-objects database since version 8 oracle rdbms also supports locally managed tablespaces store space management information bitmaps headers rather codice_1 tablespace happens default dictionary-managed tablespaces version 10 g later introduced codice_4 tablespace contains tables formerly stored codice_1 tablespace along objects tools oem previously required tablespace disk files primarily represent one following structures physical level data files comprise one data blocks block size vary data files data files occupy pre-allocated space file system computer server use raw disk directly exist within asm logical volumes oracle database installations come default schema called codice_6 installation process sets sample tables user logs database username codice_7 password codice_8 name codice_6 schema originated bruce scott one first employees oracle software development laboratories cat named tiger oracle corporation de-emphasizes codice_6 schema uses features recent oracle releases examples supplied oracle corporation reference default hr oe schemas default schemas include oracle instance uses system global area sga—a shared-memory area—to store data control-information oracle instance allocates sga starts de-allocates shut-down time information sga consists following elements fixed size established instance startup every oracle database one physical datafiles contain database data data logical database structures tables indexes physically stored datafiles allocated database datafiles following characteristics data datafile read needed normal database operation stored memory cache oracle database example user wants access data table database requested information already memory cache database read appropriate datafiles stored memory modified new data necessarily written datafile immediately reduce amount disk access increase performance data pooled memory written appropriate datafiles start instance using enterprise manager sql*plus amount memory allocated sga displayed. link library cache stores shared sql caching parse tree execution plan every unique sql statement multiple applications issue sql statement application access shared sql area reduces amount memory needed reduces processing-time used parsing execution planning data dictionary comprises set tables views map structure database oracle databases store information logical physical structure database data dictionary contains information oracle instance frequently accesses data dictionary parse sql statements oracle operation depends ready access data dictionary—performance bottlenecks data dictionary affect oracle users database administrators must make sure data dictionary cache sufficient capacity cache data without enough memory data-dictionary cache users see severe performance degradation allocating sufficient memory shared pool data dictionary cache resides precludes particular performance problem program global area pga memory-area oracle instance contains data control-information oracle server-processes background process every server background process pga total pga elements called instance pga size content pga depends oracle-server options installed area consists following components dbas monitor pga usage via system view dynamic performance views also known fixed views within oracle database present information virtual tables x tables built basis database memory database users access v views named prefix synonyms obtain information database structures performance oracle rdbms typically relies group processes running simultaneously background interacting monitor expedite database operations typical operating environments might include – temporarily permanently – following individual processes shown along abbreviated nomenclature oracle database terminology distinguishes different computer-science terms describing end-users interact database session within instance session identifier – session id sid distinct oracle system-identifier sid may also associated spid operating-system process identifier oracle databases control simultaneous access data resources locks alternatively documented enqueues databases also use latches – low-level serialization mechanisms protect shared data structures system global area oracle locks fall three categories note course multiple releases oracle reduced number instances exclusive ddl lock required making changes schema objects non-blocking ddl added 11.2 non-blocking ddl added list 12.1 non-blocking ddl added list 12.2 non-blocking ddl added list 18.1 database administrators control many tunable variations oracle instance means values parameter file file ascii default form pfile normally name format codice_21 default binary equivalent server parameter file spfile dynamically reconfigurable extent defaults format codice_22 within sql-based environment views codice_23 codice_24 give access reading parameter values implementation oracle dbms kernel code depends c programming database administrators limited access oracle-internal c structures via v views underlying x tables layers modules kernel depending different releases may include following given inferred meaning scheduler dbms_scheduler package available oracle 10g onwards job subsystems dbms_job package permit automation predictable processing oracle resource manager aims allocate cpu resources users groups users resources become scarce oracle release 10.2 database resource manager operates enterprise edition oracle corporation stated product announcements manageability dbas improved oracle9i 10g lungu vătuiu 2008 assessed relative manageability performing common dba tasks measuring timings performed tests single pentium cpu 1.7 ghz 512 mb ram running windows server 2000 oracle9i 10g installation improved 36 day-to-day administration 63 backup recovery 63 performance diagnostics tuning 74 weighted total improvement 56 researchers concluded oracle10g represents giant step forward oracle9i making database easier use manage various file-system structures hold logs trace files record different aspects database activity configurable destinations records include oracle net services allow client remote applications access oracle databases via network sessions using various protocols oracle database software comes 63 language-versions including regional variations british english american english variations versions cover names days months abbreviations time-symbols a.m. a.d. sorting oracle corporation translated oracle database error-messages arabic catalan chinese czech danish dutch english finnish french german greek hebrew hungarian italian japanese korean norwegian polish portuguese romanian russian slovak spanish swedish thai turkish oracle corporation provides database developers tools mechanisms producing internationalized database applications referred internally globalization
|
Databases
|
secure shell secure shell ssh cryptographic network protocol operating network services securely unsecured network typical applications include remote command-line login remote command execution network service secured ssh ssh provides secure channel unsecured network client–server architecture connecting ssh client application ssh server protocol specification distinguishes two major versions referred ssh-1 ssh-2 standard tcp port ssh 22 ssh generally used access unix-like operating systems also used microsoft windows windows 10 uses openssh default ssh client ssh designed replacement telnet unsecured remote shell protocols berkeley rlogin rsh rexec protocols protocols send information notably passwords plaintext rendering susceptible interception disclosure using packet analysis encryption used ssh intended provide confidentiality integrity data unsecured network internet although files leaked edward snowden indicate national security agency sometimes decrypt ssh allowing read contents ssh sessions ssh uses public-key cryptography authenticate remote computer allow authenticate user necessary several ways use ssh one use automatically generated public-private key pairs simply encrypt network connection use password authentication log another use manually generated public-private key pair perform authentication allowing users programs log without specify password scenario anyone produce matching pair different keys public private public key placed computers must allow access owner matching private key owner keeps private key secret authentication based private key key never transferred network authentication ssh verifies whether person offering public key also owns matching private key versions ssh important verify unknown public keys i.e associate public keys identities accepting valid accepting attacker public key without validation authorize unauthorized attacker valid user unix-like systems list authorized public keys typically stored home directory user allowed log remotely file ~/.ssh/authorized_keys file respected ssh writable anything apart owner root public key present remote end matching private key present local end typing password longer required software like message passing interface mpi stack may need password-less access run properly however additional security private key locked passphrase private key also looked standard places full path specified command line setting option -i ssh ssh-keygen utility produces public private keys always pairs ssh also supports password-based authentication encrypted automatically generated keys case attacker could imitate legitimate server side ask password obtain man-in-the-middle attack however possible two sides never authenticated ssh remembers key server side previously used ssh client raises warning accepting key new previously unknown server password authentication disabled ssh typically used log remote machine execute commands also supports tunneling forwarding tcp ports x11 connections transfer files using associated ssh file transfer sftp secure copy scp protocols ssh uses client-server model standard tcp port 22 assigned contacting ssh servers ssh client program typically used establishing connections ssh daemon accepting remote connections commonly present modern operating systems including macos distributions linux openbsd freebsd netbsd solaris openvms notably versions windows prior 1709 include ssh default proprietary freeware open source e.g putty version openssh part cygwin versions various levels complexity completeness exist file managers unix-like systems e.g konqueror use fish protocol provide split-pane gui drag-and-drop open source windows program winscp provides similar file management synchronization copy remote delete capability using putty back-end winscp putty available packaged run directly usb drive without requiring installation client machine setting ssh server windows typically involves enabling feature settings app windows 10 version 1709 official win32 port openssh available ssh important cloud computing solve connectivity problems avoiding security issues exposing cloud-based virtual machine directly internet ssh tunnel provide secure path internet firewall virtual machine 1995 tatu ylönen researcher helsinki university technology finland designed first version protocol called ssh-1 prompted password-sniffing attack university network goal ssh replace earlier rlogin telnet ftp rsh protocols provide strong authentication guarantee confidentiality ylönen released implementation freeware july 1995 tool quickly gained popularity towards end 1995 ssh user base grown 20,000 users fifty countries december 1995 ylönen founded ssh communications security market develop ssh original version ssh software used various pieces free software gnu libgmp later versions released ssh communications security evolved increasingly proprietary software estimated year 2000 number users grown 2 million secsh official internet engineering task force ietf name ietf working group responsible version 2 ssh protocol 2006 revised version protocol ssh-2 adopted standard version incompatible ssh-1 ssh-2 features security feature improvements ssh-1 better security example comes diffie–hellman key exchange strong integrity checking via message authentication codes new features ssh-2 include ability run number shell sessions single ssh connection due ssh-2 superiority popularity ssh-1 implementations libssh v0.8.0+ lsh dropbear support ssh-2 protocol january 2006 well version 2.1 established rfc 4253 specified ssh server supports 2.0 prior versions ssh identify protoversion 1.99 actual version method identify backward compatibility 1999 developers wanting free software version available went back older 1.2.12 release original ssh program last released open source license björn grönvall ossh subsequently developed codebase shortly thereafter openbsd developers forked grönvall code extensive work creating openssh shipped 2.6 release openbsd version portability branch formed port openssh operating systems openssh single popular ssh implementation coming default large number operating systems ossh meanwhile become obsolete openssh continues maintained supports ssh-2 protocol expunged ssh-1 support codebase openssh 7.6 release ssh protocol used many applications across many platforms including unix variants linux bsds including apple macos solaris well microsoft windows applications may require features available compatible specific ssh clients servers example using ssh protocol implement vpn possible presently openssh server client implementation secure shell protocols used several file transfer mechanisms ssh-2 protocol internal architecture defined rfc 4251 well-separated layers namely open architecture provides considerable flexibility allowing use ssh variety purposes beyond secure shell functionality transport layer alone comparable transport layer security tls user-authentication layer highly extensible custom authentication methods connection layer provides ability multiplex many secondary sessions single ssh connection feature comparable beep available tls intended performance enhancements ssh products 1998 vulnerability described ssh 1.5 allowed unauthorized insertion content encrypted ssh stream due insufficient data integrity protection crc-32 used version protocol fix known ssh compensation attack detector introduced implementations many updated implementations contained new integer overflow vulnerability allowed attackers execute arbitrary code privileges ssh daemon typically root january 2001 vulnerability discovered allows attackers modify last block idea-encrypted session month another vulnerability discovered allowed malicious server forward client authentication another server since ssh-1 inherent design flaws make vulnerable generally considered obsolete avoided explicitly disabling fallback ssh-1 modern servers clients support ssh-2 november 2008 theoretical vulnerability discovered versions ssh allowed recovery 32 bits plaintext block ciphertext encrypted using standard default encryption mode cbc straightforward solution use ctr counter mode instead cbc mode since renders ssh resistant attack december 28 2014 der spiegel published classified information leaked whistleblower edward snowden suggests national security agency may able decrypt ssh traffic technical details associated process disclosed analysis 2017 hacking tools bothanspy gyrfalcon suggested ssh protocol compromised following rfc publications ietf secsh working group document ssh-2 proposed internet standard later modified expanded following publications addition openssh project includes several vendor protocol specifications/extensions
|
Internet protocols
|
microsoft query microsoft query visual method creating database queries using examples based text string name document list documents qbe system converts user input formal database query using structured query language sql backend allowing user perform powerful searches without explicitly compose sql without even needing know sql derived moshé m. zloof original query example qbe implemented mid-1970s ibm research centre yorktown new york context microsoft access qbe used introducing students database querying user-friendly database management system small businesses microsoft excel allows results qbe queries embedded spreadsheets
|
Databases
|
capsa software capsa name family packet analyzer developed colasoft network administrators monitor troubleshoot analyze wired wireless networks currently three editions available capsa enterprise edition capsa standard edition capsa free edition capsa enterprise edition flagship colasoft capsa packet analyzer family supports ethernet wlan networks performs real-time packet capturing analysis well supporting past-events analysis marketed tool enterprise network administrator help deal daily network work various kinds network problem maintain productive enterprise network capsa standard edition ethernet packet analyzer designed networking professionals small business network administrators marketed network tool network monitoring troubleshooting analyzing purposes capsa free edition freeware ethernet packet analyzer designed colasoft personal use marketed tool network geeks learn protocols packets networking related knowledge free charge personal family users network monitoring troubleshooting needs anyone download capsa free edition colasoft website legal noncommercial use
|
Computer security
|
network time protocol network time protocol ntp networking protocol clock synchronization computer systems packet-switched variable-latency data networks operation since 1985 ntp one oldest internet protocols current use ntp designed david l. mills university delaware ntp intended synchronize participating computers within milliseconds coordinated universal time utc uses intersection algorithm modified version marzullo algorithm select accurate time servers designed mitigate effects variable network latency ntp usually maintain time within tens milliseconds public internet achieve better one millisecond accuracy local area networks ideal conditions asymmetric routes network congestion cause errors 100 ms protocol usually described terms client-server model easily used peer-to-peer relationships peers consider potential time source implementations send receive timestamps using user datagram protocol udp port number 123 also use broadcasting multicasting clients passively listen time updates initial round-trip calibrating exchange ntp supplies warning impending leap second adjustment information local time zones daylight saving time transmitted current protocol version 4 ntpv4 proposed standard documented backward compatible version 3 specified /small 1979 network time synchronization technology used possibly first public demonstration internet services running trans-atlantic satellite network national computer conference new york technology later described 1981 internet engineering note ien 173 public protocol developed documented technology first deployed local area network part hello routing protocol implemented fuzzball router experimental operating system used network prototyping ran many years related network tools available include daytime time protocols recording time events well icmp timestamp ip timestamp option complete synchronization systems although lacking ntp data analysis clock disciplining algorithms include unix daemon timed uses election algorithm appoint server clients digital time synchronization service dtss uses hierarchy servers similar ntp stratum model 1985 ntp version 0 ntpv0 implemented fuzzball unix ntp packet header round-trip delay offset calculations persisted ntpv4 documented despite relatively slow computers networks available time accuracy better 100 milliseconds usually obtained atlantic spanning links accuracy tens milliseconds ethernet networks 1988 much complete specification ntpv1 protocol associated algorithms published drew experimental results clock filter algorithm documented first version describe client-server peer-to-peer modes 1991 ntpv1 architecture protocol algorithms brought attention wider engineering community publication article david l. mills ieee transactions communications 1989 published defining ntpv2 means state machine pseudocode describe operation introduced management protocol cryptographic authentication scheme survived ntpv4 bulk algorithms era also largely survived ntpv4 1992 defined ntpv3 rfc included analysis sources error reference clock final client enabled calculation metric helps choose best server several candidates appear disagree broadcast mode introduced subsequent years new features added algorithm improvements made became apparent new protocol version required 2010 published containing proposed specification ntpv4 protocol significantly moved since 2014 updated rfc yet published following retirement mills university delaware reference implementation currently maintained open source project led harlan stenn ntp uses hierarchical semi-layered system time sources level hierarchy termed stratum assigned number starting zero reference clock top server synchronized stratum n server runs stratum n 1 number represents distance reference clock used prevent cyclical dependencies hierarchy stratum always indication quality reliability common find stratum 3 time sources higher quality stratum 2 time sources brief description strata 0 1 2 3 provided upper limit stratum 15 stratum 16 used indicate device unsynchronized ntp algorithms computer interact construct bellman-ford shortest-path spanning tree minimize accumulated round-trip delay stratum 1 servers clients addition stratum protocol able identify synchronization source server terms reference identifier refid 64-bit timestamps used ntp consist 32-bit part seconds 32-bit part fractional second giving time scale rolls every 2 seconds 136 years theoretical resolution 2 seconds 233 picoseconds ntp uses epoch january 1 1900 therefore first rollover occurs february 7 2036 ntpv4 introduces 128-bit date format 64 bits second 64 bits fractional-second most-significant 32-bits format era number resolves rollover ambiguity cases according mills 64-bit value fraction enough resolve amount time takes photon pass electron speed light 64-bit second value enough provide unambiguous time representation universe goes dim typical ntp client regularly polls one ntp servers client must compute time offset round-trip delay time offset θ difference absolute time two clocks defined round-trip delay δ values θ δ passed filters subjected statistical analysis outliers discarded estimate time offset derived best three remaining candidates clock frequency adjusted reduce offset gradually creating feedback loop accurate synchronization achieved incoming outgoing routes client server symmetrical nominal delay routes common nominal delay systematic bias exists half difference forward backward travel times ntp reference implementation along protocol continuously developed 20 years backwards compatibility maintained new features added contains several sensitive algorithms especially discipline clock misbehave synchronized servers use different algorithms software ported almost every computing platform including personal computers runs daemon called ntpd unix service windows reference clocks supported offsets filtered analysed way remote servers although usually polled frequently implementation audited 2017 finding numerous potential security issues simple network time protocol sntp less complex implementation ntp using protocol without requiring storage state extended periods time used embedded systems applications full ntp capability required microsoft windows versions since windows 2000 include windows time service w32time ability synchronize computer clock ntp server w32time originally implemented purpose kerberos version 5 authentication protocol required time within 5 minutes correct value prevent replay attacks version windows 2000 windows xp implements sntp violates several aspects ntp version 3 standard beginning windows server 2003 windows vista compliant implementation ntp included microsoft states w32time reliably maintain time synchronization one second accuracy higher accuracy desired microsoft recommends using newer version windows different ntp implementation windows 10 windows server 2016 support 1 ms time accuracy certain operating conditions 2004 henning brauer presented openntpd ntp implementation focus security encompassing privilege separated design whilst aimed closely simpler generic needs openbsd users also includes protocol security improvements whilst still compatible existing ntp servers originally designed openbsd portable version available made available package linux package repositories new ntp client ntimed started poul-henning kamp 2014 new implementation sponsored linux foundation replacement reference implementation determined easier write new implementation scratch fix existing issues large existing code base june 2015 official release done yet ntimed synchronize clocks reliably ntimed works debian freebsd remains ported windows macos ntpsec fork reference implementation systematically security-hardened fork point june 2015 response rash compromises 2014 first production release shipped october 2017 removal unsafe features removal support obsolete hardware removal support obsolete unix variants ntpsec able pare away 75 original codebase making remainder auditable 2017 audit code showed eight security issues including two present original reference implementation ntpsec suffer eight issues remained reference implementation chrony comes default red hat distributions available ubuntu repositories chrony aimed ordinary computers unstable go sleep mode intermittent connection internet chrony also designed virtual machines much unstable environment characterized low resource consumption cost supports ptp well ntp two main components chronyd daemon executed computer starts chronyc command line interface user configuration evaluated safe incidents advantage versatility code written scratch avoid complexity code chrony written gnu general public license version 2 created richard curnow 1997 others along time currently maintained miroslav lichvar development supported red hat software day leap second event ntpd receives notification either configuration file attached reference clock remote server requirement time must appear monotonically increasing leap second inserted sequence 23:59:59 23:59:60 00:00:00 although clock actually halted event processes query system time cause increase tiny amount preserving order events negative leap second ever become necessary would deleted sequence 23:59:58 00:00:00 skipping 23:59:59 alternative implementation called leap smearing consists introducing leap second incrementally period 24 hours noon noon utc time implementation used google internally public ntp servers amazon aws security problems identified reference implementation ntp codebase ones appeared 2009 cause significant concern protocol undergoing revision review entire history january 2011 security revisions ntp specification reports cert current codebase reference implementation undergoing security audits several sources several years known high-risk vulnerabilities current released software several security concerns arose late 2014 previously researchers became aware ntp servers susceptible man-in-the-middle attacks unless packets cryptographically signed authentication computational overhead involved make impractical busy servers particularly denial service attacks ntp message spoofing used move clocks client computers allow number attacks based bypassing cryptographic key expiration services affected fake ntp messages identified tls dnssec various caching schemes dns cache bgp bitcoin number persistent login schemes 2017 security audit three ntp implementations conducted behalf linux foundation core infrastructure initiative suggested ntp ntpsec problematic chrony security standpoint ntp used distributed denial service ddos attacks small query sent ntp server return address spoofed target address similar dns amplification attack server responds much larger reply allows attacker substantially increase amount data sent target avoid participating attack servers configured ignore external queries upgraded version 4.2.7p26 later stack-based buffer overflow exploit discovered patch available december 19 2014 includes ntp version 4 releases version 4.2.8 apple concerned enough used auto-update capability first time though recent versions macos case version 10.6.8 manual fixes server version normal client users turn automatic time updating system preferences date time implementation errors basic missing return statement routine lead unlimited access systems running versions ntp root daemon systems use root daemon bsd subject flaw
|
Internet protocols
|
measuring programming language popularity difficult determine programming languages widely used usage means varies context one language may occupy greater number programmer hours different one lines code third may utilize cpu time languages popular particular kinds applications example cobol still strong corporate data center often large mainframes fortran computational science engineering c embedded applications operating systems languages regularly used write many different kinds applications various methods measuring language popularity subject different bias measured proposed several indices published
|
Programming language topics
|
kismac kismac wireless network discovery tool mac os x wide range features similar kismet linux/bsd namesake program geared toward network security professionals novice-friendly similar applications distributed gnu general public license kismac free software kismac scan networks passively supported cards including apple airport airport extreme many third-party cards actively card supported mac os x cracking wep wpa keys brute force exploiting flaws weak scheduling badly generated keys supported card capable monitor mode used packet reinjection done supported card prism2 ralink cards gps mapping performed nmea compatible gps receiver attached kismac2 fork original software new gui new features works os x 10.7 10.10 64-bit longer maintained data also saved pcap format loaded programs wireshark project created led michael rossberg july 27 2007 removed project due changes german law specifically stgb section 202c prohibits production distribution security software date project lead passed geoffrey kruse maintainer kismac since 2003 active developer since 2001 kismac longer actively developed primary development relocated kismac web site offline september 2016 august 6 2007 former homepage denounces new german law kismac2 project continue development longer maintained well
|
Computer security
|
stklos stklos scheme implementation succeeded stk interpreter based ad hoc virtual machine aims fast well light addition implementing rrs stklos supports additional libraries available package system scmpkg
|
Programming language topics
|
supply chain attack supply chain attack cyber-attack seeks damage organization targeting less-secure elements supply network supply chain attack occur industry financial sector oil industry government sector cybercriminals typically tamper manufacturing process product installing rootkit hardware-based spying components internet security threat report powered symantec stated supply chain attacks still continues feature threat landscape increase 78 percent 2018 recent target security breach eastern european atm malware well stuxnet computer worm examples supply chain attacks supply chain management experts recommend strict control institution supply network order prevent potential damage cybercriminals supply chain system activities involved handling distributing manufacturing processing goods order move resources vendor hands final consumer supply chain complex network interconnected players governed supply demand although supply chain attack broad term without universally agreed upon definition reference cyber-security supply chain attack involves physically tampering electronics computers atms power systems factory data networks order install undetectable malware purpose bringing harm player supply chain network general sense supply chain attack may necessarily involve electronics 2010 burglars gained access pharmaceutical giant eli lilly supply warehouse drilling hole roof loading 80 million worth prescription drugs truck could also said carry supply chain attack however article discuss cyber attacks physical supply networks rely technology hence supply chain attack method used cyber-criminals generally supply chain attacks information systems begin advanced persistent threat determines member supply network weakest cyber security order affect target organization according investigation produced verizon enterprise 92 cyber security incidents analyzed survey occurred among small firms apt often gain access sensitive information physically tampering production product october 2008 european law-enforcement officials uncovered highly sophisticated credit-card fraud ring stole customer account details using untraceable devices inserted credit-card readers made china gain access account information make repeated bank withdrawals internet purchases amounting estimated 100 million losses threat supply chain attack poses significant risk modern day organizations attacks solely limited information technology sector supply chain attacks affect oil industry large retailers pharmaceutical sector virtually industry complex supply network information security forum explains risk derived supply chain attacks due information sharing suppliers states sharing information suppliers essential supply chain function yet also creates risk ... information compromised supply chain damaging compromised within organization muhammad ali nasir national university emerging sciences associates above-mentioned risk wider trend globalization stating …due globalization decentralization outsourcing supply chains numbers exposure points also increased greater number entities involved scattered around globe… cyber-attack supply chain destructive way damage many linked entities due ripple effect poorly managed supply chain management systems become significant hazards cyber attacks lead loss sensitive customer information disruption manufacturing process could damage company reputation wired reported connecting thread recent software supply chain attacks 05.03.19 surmised spread infected pirated popular compilers posted pirate websites corrupted versions apple xcode microsoft visual studio end 2013 target us retailer hit one largest data breaches history retail industry november 27 december 15 2013 target american brick-and-mortars stores experienced data hack around 40 million customers credit debit cards became susceptible fraud malware introduced pos system 1,800 stores data breach target customer information saw direct impact company profit fell 46 percent fourth quarter 2013 six months prior company began installing 1.6 million cyber security system target team security specialists monitor computers constantly nonetheless supply chain attack circumvented security measures believed cyber criminals infiltrated third party supplier gain access target main data network although officially confirmed investigation officials suspect hackers first broke target network november 15 2013 using passcode credentials stolen fazio mechanical services pennsylvania-based provider hvac systems 90 lawsuits filed target customers carelessness compensatory damages target spent around 61 million responding breach according fourth-quarter report investors believed american-israeli cyber weapon stuxnet malicious computer worm worm specifically targets systems automate electromechanical processes used control machinery factory assembly lines equipment separating nuclear material computer worm said specifically developed order damage potential uranium enrichment programs government iran kevin hogan senior director security response symantec reported majority infected systems stuxnet worm located islamic republic iran led speculation may deliberately targeting high-value infrastructure country including either bushehr nuclear power plant natanz nuclear power plant stuxnet typically introduced supply network via infected usb flash drive persons physical access system worm travels across cyber network scanning software computers controlling programmable logic controller plc stuxnet introduces infected rootkit onto plc modifying codes giving unexpected commands plc returning loop normal operation value feedback users recent years malware known suceful plotus tyupkin greendispense affected automated teller machines globally especially russia ukraine greendispenser specifically gives attackers ability walk infected atm system remove cash vault installed greendispenser may display ‘ service ’ message atm attackers right access credentials drain atm cash vault remove malware system using untraceable delete process types malware usually behave similar fashion capturing magnetic stripe data machine memory storage instructing machines withdraw cash attacks require person insider access atm technician anyone else key machine place malware atm tyupkin malware active march 2014 50 atms banking institutions eastern europe believed also spread time u.s. india china malware affects atms major manufacturers running microsoft windows 32-bit operating systems malware displays information much money available every machine allows attacker withdraw 40 notes selected cassette atm spring 2017 core code financial package m.e.doc used ukraine infected notpetya virus subsequently download subscribers hack carried provider system either hacking code provider hack re-routing download requests another server press reports time make clear supply chain attack attack vector used specified august september 2018 british airways website payment section contained code harvested customer payment data injected code written specifically route credit card information website domain baways.com could erroneously thought belong british airways comprehensive national cybersecurity initiative cyberspace policy review passed bush obama administrations respectively direct u.s. federal funding development multi-pronged approaches global supply chain risk management according adrian davis technology innovation management review securing organizations supply chain attacks begins building cyber-resilient systems supply chain resilience according supply chain risk management expert donal walters ability supply chain cope unexpected disturbances one characteristics company-wide recognition supply chain susceptible infiltration supply chain management plays crucial role creating effective supply chain resilience march 2015 conservative liberal democratic government coalition uk department business outlined new efforts protect smes cyber attacks included measures improve supply chain resilience uk government produced cyber essentials scheme trains firms good practices protect supply chain overall cyber security depository trust clearing group american post-trade company operations implemented governance vulnerability management throughout supply chain looks security along entire development lifecycle includes software coded hardware manufactured 2014 pwc report titled threat smart building cyber resilient financial institution financial services firm recommends following approach mitigating cyber attack avoid potential damage financial institution ’ bottom line reputation brand intellectual property executive team needs take ownership cyber risk specifically collaborate front understand institution defend respond cyber risks take make organization cyber resilient fireeye us network security company provides automated threat forensics dynamic malware protection advanced cyber threats advanced persistent threats spear phishing recommends firms certain principles place create resilience supply chain include april 27 2015 sergey lozhkin senior security researcher great kaspersky lab spoke importance managing risk targeted attacks cyber-espionage campaigns conference cyber security stated mitigation strategies advanced threats include security policies education network security comprehensive system administration specialized security solutions like ... software patching features application control whitelisting default deny mode
|
Computer security
|
commview commview application network monitoring packet analysis decoding two editions commview standard edition ethernet networks wireless edition 802.11 networks named commview wifi application runs microsoft windows developed tamosoft privately held new zealand company founded 1998 commview puts network adapter promiscuous mode captures network traffic also supports capturing packets dial-up virtual adapters e.g adsl 3g modems well capturing loopback traffic captured traffic analyzed application displays network statistics individual packets packets decoded using protocol decoder commview wifi puts wi-fi adapters monitor mode providing functionality user experience similar commview addition wlan-specific features displaying decoding management control frames indication signal noise level per-node per-channel statistics
|
Computer security
|
gale technologies gale technologies formerly known lumenare networks private company headquartered santa clara ca additional offices asia backed crescendo ventures company automates companies infrastructure delivering private hybrid cloud management orchestration software also sells management solutions converged infrastructure deployments 2008 july — lumenare networks formed includes acquired intellectual property two companies quikcycle edentree technologies later renamed gale technologies 2010 2012 march — gale technologies completes acquisition virtiv technology intellectual property 2012 16 nov — dell announces acquisition gale technologies
|
Distributed computing architecture
|
mos technology 6509 mos technology 6509 enhanced version popular 6502 microprocessor capable addressing 1 megabyte ram via bank switching numerous 6502-based processors could bank switching via separate logic 6509 logic on-chip 6509 reputation difficult program due bank switching scheme never fared well used ill-fated commodore cbm-ii line computers
|
Computer architecture
|
ghostscript ghostscript suite software based interpreter adobe systems postscript portable document format pdf page description languages main purposes rasterization rendering page description language files display printing document pages conversion postscript pdf files ghostscript used raster image processor rip raster computer printers—for instance input filter line printer daemon—or rip engine behind postscript pdf viewers ghostscript also used file format converter postscript pdf converter codice_1 conversion program comes ghostscript distribution described documentation work-alike nearly functionality user interface adobe acrobat distiller product converter basically thin wrapper around ghostscript codice_2 output device supports pdf/a-1 pdf/a-2 well pdf/x-3 output ghostscript also serve back-end pdf raster image png tiff jpeg etc converter often combined postscript printer driver virtual printer pdf creators takes form language interpreter ghostscript also used general purpose programming environment ghostscript ported many operating systems including unix-like systems classic mac os openvms microsoft windows plan 9 ms-dos freedos os/2 atari tos amigaos ghostscript originally written l. peter deutsch gnu project released gnu general public license 1986 later deutsch formed aladdin enterprises dual-license ghostscript also proprietary license development fork aladdin ghostscript aladdin free public license despite name free software license forbids commercial distribution gnu ghostscript distributed gnu general public license version 8.54 2006 development branches merged dual-licensed releases still provided ghostscript currently owned artifex software maintained artifex software employees worldwide user community according artifex version 9.03 commercial version ghostscript longer freely distributed commercial purposes without purchasing license though gpl variant allows commercial distribution provided code using released gpl artifex point view aggregated software challenged court mupdf february 2013 ghostscript changed license gplv3 gnu agpl version 9.07 raised license compatibility questions example debian ghostscript guis view postscript pdf files screens scroll page forward page backward zoom text print page several sets free fonts supplied ghostscript intended metrically compatible common fonts attached postscript standard include ghostscript fonts developed postscript type 1 format converted truetype format usable current software popularly used within open-source community garamond font additionally improved upon urw core 35 fonts subsequently incorporated gnu freefont tex gyre
|
Programming language topics
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.