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andos andos russian operating system electronika bk-0010 electronika bk-0011 electronika bk-0011m series computers created 1990 first released 1992 initially developed alexey nadezhin whose name system named later also sergey kamnev joined project widespread system bk series computers used ms-dos-compatible file system format andos used fat12 filesystem 800 kb floppy disks electronika bk-0011m electronika bk-0011 andos provided electronika bk-0010 emulation loading bk-0010 rom image bk-0011 ram minimal configuration system able occupy less 4 kb ram system able support 64 disk drives hard drive partitions well ram disks computer memory tape recording also able read-only access microdos file system format disks although last version function transferred system core file manager became optional
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Operating systems
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fantasy zone ii tears opa-opa past courageous hero opa-opa saved fantasy zone invading nenon forces victory came price forced fight father led invasion space year 1432 10 years battle nenon forces spreading chaos fantasy zone opa-opa must fly fantasy zone rout invasion end game opa-opa comes face-to-face invasion mastermind identical copy tense battle opa-opa father appears confront sight brings opa-opa tears causes second opa-opa vanish later revealed twin physical manifestation opa-opa dark impulses desires spawned prior battles seeking drive fantasy zone ruin reunited father opa-opa able purge darkness swears disaster never occur similar defender player occupies side-scrolling level repeats indefinitely player freely travel left right zone contains several bases serve primary targets new sequel warps hidden behind certain bases allow player travel different zones level least three zones bases cleared zones level player travel warp boss boss fights allow free travel main stages force player face boss face particular direction bosses generally large change color reflect damage taken final stage boss rush player must fight succession previous bosses fighting final boss two action buttons correspond two types attacks fire bomb fire attacks shoot horizontally typical shooter different variants purchased shops bomb attacks powerful basic bomb drops downward variants behaviors limited quantity shops uncovered key points allow player purchase upgraded weapons bombs speed well extra lives upgrades opa-opa speed larger wings jet engines permanent long player lose life weapon upgrades time-limited bombs limited quantity items become increasingly expensive subsequent purchases encouraging player vary purchases arcade version fantasy zone ii based system e board result almost identical master system version differences include use radar shows bases destroyed well use timer reaches zero player lose life player manages clear level timer remaining seconds add score money unlike original version famicom port subtitle title screen says teardrop opa-opa september 2008 sega released remake fantasy zone ii part compilation sega ages vol 33 fantasy zone complete collection developed m2 game unique remakes attempt modernize older work rather ground-up reimagining title arcade game system 16 hardware like predecessor rather console title limited sega master system described remake strictly adheres technical limitations time fantasy zone ii originally released m2 ceo naoki horii stated remake inspired disappointment fantasy zone never got true arcade sequel played sms game lot horii explained heart hearts really wanted see arcade hardware ensure remake would authentic system 16 unique hardware capabilities limitations m2 developed title real system 16 hardware modest memory increase 256kb m2 dubbed system 16c playable compilation via company emulation technology shows 1987 sega copyright makes mention m2 bears titular distinction original game easily confused real arcade title 1987 fans dubbed version fantasy zone ii dx distinguish original versions remake beyond scope features requested sega available budget horii funded development out-of-pocket amount described cost new car follows original fantasy zone ii loosely pulling enemies music locations gameplay elements master system game pairing completely new content elements original arcade fantasy zone notable change level structure rather several distinct zones stage must cleared stage remake two parallel dimensions bright side dark side comparable size levels first fantasy zone bases destroyed one dimension also destroyed making possible clear level entirely one side dark side difficult offers greater rewards points money earned bosses either side considerably difficult attack patterns dark side game also features three endings depend whether dark side levels cleared whether specific items bought music arranged manabu namiki uses melodies many songs tokuhiko uwabo original fantasy zone ii soundtrack calculatedly rearranged style similar original fantasy zone composer hiroshi kawaguchi namiki also wrote original tracks game stages enemies largely based themes original difficult recognize half game bosses correspond original generally regarded loose interpretation original m2 released free demo version fantasy zone ii website lets download play first second levels windows computer game bootlegged released arcades title fz-2006 ii taiwanese manufacturer isg bootleg bears 2006 copyright date actually appears derived 2008 playstation 2 release due containing 2008-07-15ver string embedded rom data sega also produced limited number arcade units running real system 16 hardware promote game release nintendo 3ds port 16-bit version fantasy zone ii released japan 2014 internationally 2015 titled 3d fantasy zone ii w includes new features content second game mode called link loop land endless survival mode starring opa-opa brother upa-upa
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Computer architecture
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17 app 17 live video streaming mobile app designed taiwanese pop singer jeffery huang member machi features instant photo video sharing functions client apps available ios android smartphone systems first launched app store 5 june 2015 sooner play store 10 june 2015 app re-released 28 october 2015 banned due prohibited content app become one popular live streaming apps taiwan malaysia hong kong singapore japan approximately 700 thousand daily active users 17 allows users broadcast live post photos videos album privacy settings used allow access rights permitted users users also follow one another track recent status changes app complained become platform broadcasting indecent scenes live broadcast sexual intercourse process app found unauthorized broadcasting lives attracted millions audience watch founder 17 jeffery huang claimed broadcast would stopped user ’ account would deleted received complaints also responded would stricter supervision system avoid similar incidents happening april 2016 according security website customer data 17 sold tor hidden website data include 4 million email addresses along ip addresses usernames unsalted md5 passwords users registered around time change passwords
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Operating systems
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powerbuilder powerbuilder integrated development environment owned sap since acquisition sybase 2010 july 5 2016 sap appeon entered agreement whereby appeon would responsible developing selling supporting powerbuilder powerbuilder use since 1991 peaking around 1998 around 100,000 users powerbuilder market share declined years many applications created still use today years powerbuilder updated new standards 2010 major upgrade powerbuilder released provide support microsoft .net framework 2014 support added odata dockable windows 64-bit native applications 2017 support added ios android app development powerbuilder 2019 provides new targets enable developers rapidly create restful web apis non-visual .net assemblies test-driven manner using c language .net core framework powerscript client app development revamped new ui technologies cloud architecture powerbuilder native data-handling object called datawindow used create edit display data database object gives programmer number tools specifying controlling user interface appearance behavior also provides simplified access database content json xml web services extent datawindow frees programmer considering differences database management systems different vendors datawindow display data using multiple presentation styles connect various data sources powerbuilder used primarily building business crud applications although new software products rarely built powerbuilder many client-server erp products line-of-business applications built late 1980s early 2000s powerbuilder still provide core database functions large enterprises government higher education manufacturing insurance banking energy telecommunications job openings powerbuilder developers readily available often revolve around maintaining existing applications powerbuilder originally developed powersoft 1991 powersoft went public 1993 acquired sybase 904 million sybase stock 1995 may 2010 sap announced would acquiring sybase 5.8 billion powerbuilder languished long time several reasons powerbuilder 12 compatibility web technologies asp.net web services represented attempt regain market share order move developers newer versions powerbuilder 12 provided utilities attempt simplify migration december 2013 sap announced new version going directly number 15 released beta version key features included support .net framework v4.5 sql server 2012 oracle 12 windows 8 odata dockable windows sap later released version 12.6 july 5 2016 appeon signed agreement sap develop new generation powerbuilder development platform appeon announced plans major innovations ranging mobile cloud deployment test-driven development continuous integration terms agreement sap appeon responsible developing selling supporting offering powered powerbuilder technology june 30 2017 powerbuilder 2017 launched appeon release first new installment powerbuilder appeon first release powerbuilder support windows 10 ios android app development may 31 2019 powerbuilder 2019 launched appeon release second new installment powerbuilder appeon first release powerbuilder support c development provides new c ide .net data access objects c migration solution web api client ui themes powerscript object-oriented programming language nearly visual non-visual objects support inheritance polymorphism encapsulation programmer may utilize common code framework powerbuilder foundation classes also known pfc inherit objects leverage pre-existing code datawindow key component selling point powerbuilder datawindow offers visual sql painter supports outer joins unions subquery operations convert sql visual representation back developer use native sql desired datawindow updates automatic — produces proper sql runtime based dbms user currently connected feature makes easier developers experienced sql datawindow also built-in ability retrieve data update data via stored procedures rest web apis well import/export json data restclient object introduced powerbuilder 2017 facilitates bridging datawindow rest web apis requiring minimal coding powerbuilder offers native interfaces major databases well odbc ole-db enterprise version many connectivity options allow performance monitoring tuning due information database schema primary key information stored powerbuilder data dictionary code required implement data display browsing greatly simplified dictionary information allows generation appropriate sql behind scenes powerbuilder supports following ways interacting database datawindow simplest approach relying automatically generated sql powerbuilder supports activex ocx controls visible non-visible also use ole automation client however powerbuilder supports late binding early binding therefore using ole automation dropdown possible actions provided powerbuilder also act dde client server providing mechanism interoperate applications powerbuilder make windows third-party api calls general works well third-party libraries dll files however directly support callback functions powerbuilder offers /pbdebug variants -pbdebug -pbd /debug -debug -deb runtime switch creates log file help track bug field user simply emails log file developer another feature log sql statements file also built-in performance profiling integrated debugger context-sensitive help active newsgroup provide support powerbuilder applications typically compiled p-code interpreted powerbuilder run time although compiled machine code called c-code typical business application run lot faster however applications unusually large number cpu-intensive computations likely benefit 4,000x faster compiling machine code main reason compiling machine code used enormous number errors powerbuilder especially machine code generation extensibility language rather limited older versions powerbuilder technologies provided overcome ex powerbuilder native interface pbni rather tricky develop solution includes external c++ code may require competent c++ developer also powerbuilder expert guide developer myriad subtleties language powerbuilder virtual machine inheritance object-oriented features limited object types windows userobjects menus particular possible inherit datawindow powerbuilder user open descendant parent time painter though see ancestors code working descendant address criticisms appeon set new roadmap powerbuilder publishes openly appeon website classic powerscript language still available compatibility reasons known language built around datawindow amongst developers powerbuilder ide built around datawindow c development centered around new .net datawindow automated migration existing datawindows introduced powerbuilder 2019 since appeon took powerbuilder launched new official community website powerbuilder developers community website offers technical articles webinars q authored community users appeon also hosts annual user conference called appeon elevate recordings conference sessions available conference website number local user groups around world cooperate appeon deliver abridged versions conference seminar format local language also variety grass roots community groups resources powerbuilder developers share convene powerbuildertv series webinars powerbuilder users vendors tend focus third party add-ons powerbuilder central community initiative create single source third party add-ons services
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Programming language topics
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sherpa/juliet sherpa/juliet online database open access mandates adopted academic funding bodies part sherpa suite services around open access run jisc formerly university nottingham database contains information 100 funders mostly united kingdom juliet indicates policy regarding self-archiving open access journals archival research data users suggest updates records addition new funder via form service mainly useful researchers received project-based funding want clear summary funder links original policies also provided
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Databases
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l7-filter l7-filter software package provides classifier linux netfilter subsystem categorize internet protocol packets based application layer data major goal tool make possible identification peer-to-peer programs use unpredictable port numbers two versions software first implemented kernel module linux 2.4 2.6 second experimental version released december 2006 runs user-space program relies netfilter user-space libraries classification process versions l7-filter use regular expressions though user-space kernel modules use different regular expression libraries identify network protocol technique used conjunction linux qos system allows application-specific yet port-independent traffic shaping versions l7-filter released gnu general public license
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Computer security
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net-snmp net-snmp suite software using deploying snmp protocol v1 v2c v3 agentx subagent protocol supports ipv4 ipv6 ipx aal5 unix domain sockets transports contains generic client library suite command line applications highly extensible snmp agent perl modules python modules net-snmp housed sourceforge usually top 100 projects sourceforge ranking system march 2005 sourceforge project month widely distributed comes included many operating systems including distributions linux freebsd openbsd solaris os x also available net-snmp web site steve waldbusser cmu started freely available snmp tool kit 1992 package later abandoned cmu wes hardaker uc davis renamed ucd-snmp extended meet network management needs electrical engineering department eventually mr. hardaker left university realized project network wide thus renamed net-snmp reflect distributed development roots net-snmp project long full description found net-snmp history page command snmpget uses snmpget application retrieve information associated specific object identifier oid target device example snmpget usage retrieve specific oid 'sysuptime community string 'demopublic 'test.net-snmp.org host name agent query command snmpwalk uses snmp getnext request query network tree information object identifier oid may given command line oid specifies portion object identifier space searched using getnext requests variables subtree given oid queried values presented user oid argument present snmpwalk search subtree rooted snmpv2-smi :mib-2 including mib object values mib modules defined lying within subtree example snmpwalk usage retrieve variables system oid
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Internet protocols
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file system visualizer file system visualizer also known fsv 3d file browser using opengl created daniel richard g. clone sgi fsn file manager irix systems aimed run modern linux unix-like operating systems capable representing file systems two ways mapv mode files directories represented cuboids equal height size cuboid representing size file directory treev mode files directories shown conventional tree manner links parent directories subdirectories columns various height indicating file size top directories represent files inside modes standard 2d tree representation files directories displayed left window mouse used rotate 3d representation file system eagle eye function shows representation overhead view file system visualizer also capable manipulating files directories shows
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Computer file systems
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cris thomas space rogue cris thomas also known space rogue american cyber security researcher white hat hacker founding member researcher high-profile hacker security think tank l0pht heavy industries thomas one seven l0pht members testified u.s. senate committee governmental affairs 1999 topic government homeland computer security specifically warning internet vulnerabilities claiming group could take internet within 30 minutes subsequently thomas pursued career cyber security research also embracing public advocacy role cyber security subject-matter expert sme pundit granting interviews contributing articles space rogue advocacy served educate advise corporations government public security concerns relative risk areas election integrity cyber terrorism technology anticipation new risks associated society adoption internet things balancing perspective risk vs. hype founding member hacker think tank l0pht heavy industries thomas first l0pht members leave following merger l0pht stake 2000 last reveal true name thomas one seven l0pht members testified u.s. senate committee governmental affairs 1999 testifying internet handle space rogue testimony thomas l0pht members served inform government current future internet vulnerabilities federal public channels susceptible testimony marked first time persons federal witness protection permitted testify assumed names l0pht thomas created whacked mac archives hacker news network addition released least one security advisories detailing flaw fwb hard disk toolkit thomas continued career cyber security research stake guardent trustwave spiderlabs tenable ibm x-force red selected serve panelist 2016 atlantic council cyber risk discussion series webinar speaker national science foundation watch series thomas embraced public advocacy role cyber security subject-matter expert sme pundit granting interviews contributing articles educate public security concerns relative risk topics include election integrity cyber terrorism technology password security anticipation new risks associated society adoption internet things balancing perspective risk vs. hype response 2016 united states government accountability office report revealing nation nuclear weapons control computers relied outdated 8 floppy disks thomas argued older computers data storage systems programming languages lack internet connectivity would make difficult hackers access systems effectively reducing vulnerability weapon control systems hacking following cyber security mega-breaches target home depot u.s. office personnel management thomas advocated proactive implementation basic security measures effective means thwart similar mega-threats bluntly stating gap knowledge implementation leaves companies individuals unnecessary risk thomas ’ recommendation focused simple measures known one two decades organizations implemented universally thomas identified retail cyber security breaches including fao schwarz early 1999 2017 defcon hacker conference thomas assisted escorting rep. hurd r rep. jim langevin around conference area various villages whacked mac archives ftp download site managed thomas world largest collection apple macintosh hacking tools total size tools site 20mb cd copy contents ftp site advertised sale serving editor-in-chief thomas founded managed l0pht online newsletter website known hacker news network simply hacker news hnn originally created rapidly share discoveries computer security hacker news also became forum users post security alerts vulnerabilities identified publication grew eventually supporting paid advertising audience included technology journalists companies interest cybersecurity website seen several background shots video solar sunrise dawn new threat produced national counterintelligence center 1999 l0pht merger stake 2000 responsible disclosure-focused hacker news network replaced security news network hacker news network decade offline set launch jan. 11 2010 video reports security last videos published 2011 hacker news network 2018 redirects spacerogue.net 2013 thomas created project cybersquirrel1 satirical demonstration relative risk cyberwarfare attacks critical infrastructure elements north american electrical grid started twitter feed cybersquirrel1 project expanded include full website cybersquirrel tracking map dataset grew attrition.org brian martin alias “ jared e. richo ” a/k/a jericho joined project 2014 cybersquirrel1 results disrupted public perception regarding prevalence nation-based hacking cyberwarfare attacks concluding damage due cyberwarfare example stuxnet tiny compared cyber-threat caused animals 2015-2016 alleged russian interference 2016 united states elections unfolded public media interest hacking hackers increased leading 2016 election thomas interviewed mainstream media productions including cnbc money release joint analysis report thomas called expanded detail indicators compromise federal joint analysis reports indicating increased transparency ip address reporting instrumental enhancing security prior 2018 election thomas continued advocacy speaking cbs news outlets securing elections vulnerability voting machines
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Computer security
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national grid service national e-infrastructure service nes formerly national grid service organisation uk academics researchers 2004 2011 funded two governmental bodies engineering physical sciences research council epsrc joint information systems committee jisc nes provided compute data resources accessed standard common set services nes services based globus toolkit job submission storage resource broker data management nes resources hosted scientific software packages including siesta gaussian well providing access compute data resources nes offered training national e-science centre edinburgh grid support uk academics researchers grid computing nes 500 users twenty nine sites nes gridpp two organisations made uk ngi organisation uk point contact european grid infrastructure prior nes uk e-science programme funded grid support centre later grid operations support centre gosc provided support end users use develop grid computing following uk engineering task force developing so-called 'level 2 grid ad hoc collection individual institutes committing variety compute resources grid computing nes funded develop full service initially called etfp grid engineering task force production grid became known national grid service hardware purchased installed february 2004 web site appeared april 2004 phase 1 october 2004 september 2006 worked separately funded grid operations support centre gosc start phase two october 2006 ngs gosc merged single project name nes nes third phase ran september 2011 nes provided free-to-use services uk academic researchers nes following partner sites affiliate sites provided resources nes conditions sometimes provide access users common ngs interfaces members gridpp collaboration also offered resources academics uk could apply free account nes science research ranged permeation drugs membrane welfare ethnic minority groups united kingdom applications included modelling coastal oceans modelling hiv mutations research cameras imaging patients cancer treatments simulating galaxy formation example use nes motivation methodology implementation e-social science pilot demonstrator project entitled grid enabled micro-econometric data analysis gemeda used nes investigate policy relevant social science issue welfare ethnic minority groups united kingdom underlying problem statistical analysis uses quantitative data one source application grid technology problem allows one integrate elements required empirical modelling process data extraction data transfer statistical computation results presentation manner transparent casual user examples research using nes published 2006 2011
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Distributed computing architecture
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userscript userscript user script program usually written javascript modifying web pages augment browsing desktop browsers firefox enabled use userscript manager browser extension greasemonkey presto-based opera browser supported userscripts referred user javascript placed designated directory userscripts often referred greasemonkey scripts named original userscript manager firefox wikipedia feature enabled registered users allows install userscripts augment editing viewing encyclopedia pages userscript manager type browser extension augmented browsing technology provides user interface manage scripts main purpose userscript manager execute scripts webpages loaded common operations performed userscript manager include downloading creating installing organizing deleting editing scripts well modifying script permissions e.g website exceptions one aspect userscripts shared uploaded userscript repository become available users downloading examples userscript repositories include greasy fork openuserjs
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Programming language topics
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math-matic math-matic marketing name at-3 algebraic translator 3 compiler early programming language univac univac ii math-matic written beginning around 1955 team led charles katz direction grace hopper preliminary manual produced 1957 final manual following year syntactically math-matic similar univac contemporaneous business-oriented language flow-matic differing providing algebraic-style expressions floating-point arithmetic arrays rather record structures expressions math-matic could contain numeric exponents including decimals fractions way custom typewriter math-matic programs could include inline assembler sections arith-matic code univac machine code univac 1000 words memory successor univac ii little 2000 math-matic allowed larger programs automatically generating code read overlay segments uniservo tape required compiler attempted avoid splitting loops across segments proposing collaboration acm led algol 58 gesellschaft für angewandte mathematik und mechanik wrote considered math-matic closest available language proposal contrast backus fortran math-matic emphasise execution speed compiled programs univac machines floating-point hardware math-matic translated via a-3 arith-matic pseudo-assembler code rather directly univac machine code limiting usefulness sample math-matic program
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Programming language topics
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lions commentary unix 6th edition source code lions commentary unix 6th edition source code john lions 1976 contains source code 6th edition unix kernel plus commentary commonly referred lions book despite age still considered excellent commentary simple high quality code many years lions book unix kernel documentation available outside bell labs although license 6th edition allowed classroom use source code license 7th edition specifically excluded use book spread illegal copy machine reproductions kind samizdat commonly held copied book computer science book reprinted 1996 peer-to-peer communications unix operating system source code level six kernel source code lightly edited lions better separate functionality — system initialization process management interrupts system calls basic i/o file systems pipes character devices procedures symbols listed alphabetically cross reference code presented run pdp-11/40 rk-05 disk drive lp-11 line printer interface pcl-11 paper tape writer kl-11 terminal interface suitable pdp-11 emulator simh commentary unix operating system starts notes unix useful documentation unix manual pages dec hardware manuals section architecture pdp-11 chapter read c programs source commentary follows divided sections code book ends suggested exercises student lions explains commentary supplements comments source possible understand code without extra commentary reader advised read notes needed commentary also remarks code might improved source code commentary originally produced may 1976 set lecture notes lions computer science courses 6.602b 6.657g university new south wales department computer science unix news march 1977 announced availability book unix licensees lions trouble keeping popularity 1978 available bell labs announced unix version 7 usenix june 1979 academic/research license longer automatically permitted classroom use thus licensees longer able use lions notes classes operating systems however thousands computer science students around world spread photocopies could study legally class would sometimes meet hours discuss book many pioneers unix open source treasured multiple-generation photocopy follow-on effects license change included andrew s. tanenbaum creating minix tanenbaum wrote operating systems 1987 various unix people particularly peter h. salus dennis ritchie berny goodheart lobbied unix various owners novell santa cruz operation many years allow book published officially 1996 santa cruz operation finally authorised release twenty-year-old 6th edition source code along source code versions ancient unix full code plus 1977 version commentary published peer-to-peer communications reissue includes commentary michael tilson sco peter salus dennis ritchie ken thompson peter collinson greg rose mike o'dell berny goodheart peter reintjes infamous program comment expected understand occurs line 2238 source code lions commentary p. 22 end comment explaining process exchange mechanism refers line 325 file slp.c source code reads major reason piece code hard understand depended quirk way c-compiler pdp-11 saved registers procedure calls code failed ported machines redesigned version 7 unix dennis ritchie later explained meaning remark xv6 modern reimplementation sixth edition unix ansi c multiprocessor x86 systems
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Operating systems
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distributed memory computer science distributed memory refers multiprocessor computer system processor private memory computational tasks operate local data remote data required computational task must communicate one remote processors contrast shared memory multiprocessor offers single memory space used processors processors aware data resides except may performance penalties race conditions avoided distributed memory system typically processor memory form interconnection allows programs processor interact interconnect organised point point links separate hardware provide switching network network topology key factor determining multiprocessor machine scales links nodes implemented using standard network protocol example ethernet using bespoke network links used example transputer using dual-ported memories key issue programming distributed memory systems distribute data memories depending problem solved data distributed statically moved nodes data moved demand data pushed new nodes advance example problem described pipeline data x processed subsequently functions f g h etc result h g f x expressed distributed memory problem data transmitted first node performs f passes result onto second node computes g finally third node computes h also known systolic computation data kept statically nodes computations happen locally changes edges reported nodes example simulation data modeled using grid node simulates small part larger grid every iteration nodes inform neighboring nodes new edge data similarly distributed shared memory node cluster access large shared memory addition node limited non-shared private memory distributed shared memory hides mechanism communication hide latency communication
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Distributed computing architecture
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bidirectional forwarding detection bidirectional forwarding detection bfd network protocol used detect faults two forwarding engines connected link provides low-overhead detection faults even physical media n't support failure detection kind ethernet virtual circuits tunnels mpls label switched paths bfd establishes session two endpoints particular link one link exists two systems multiple bfd sessions may established monitor one session established three-way handshake torn way authentication may enabled session choice simple password md5 sha1 authentication available bfd discovery mechanism sessions must explicitly configured endpoints bfd may used many different underlying transport mechanisms layers operates independently therefore needs encapsulated whatever transport uses example monitoring mpls lsps involves piggybacking session establishment lsp-ping packets protocols support form adjacency setup ospf is-is may also used bootstrap bfd session protocols may use bfd receive faster notification failing links would normally possible using protocol keepalive mechanism session may operate one two modes asynchronous mode demand mode asynchronous mode endpoints periodically send hello packets number packets received session considered demand mode hello packets exchanged session established assumed endpoints another way verify connectivity perhaps underlying physical layer however either host may still send hello packets needed regardless mode use either endpoint may also initiate echo function function active stream echo packets sent endpoint sends back sender via forwarding plane used test forwarding path remote system june 2011 bfd protocol standardization process entered proposed standard stage rfc 5880 defines bfd protocol detecting mpls lsp failure using bfd monitor connectivity across multiple network hops using bfd ipv4 ipv6 bfd operation conjunction open shortest path first ospf is-is protocols also outlined rfc 5881
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Internet protocols
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canmore database canmore online database information 320,000 archaeological sites monuments buildings scotland begun royal commission ancient historical monuments scotland historic environment scotland maintained since 2015 canmore database part national record historic environment nrhe formerly national monuments record scotland nmrs contains around 1.3 million catalogue entries includes marine monuments designated official wreck sites fall protection wrecks act wreck
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Databases
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unisys 2200 series system architecture figure shows high-level architecture os 2200 system identifying major hardware software components majority unisys software included subsystems applications area model example database managers subsystems compilers applications details system architecture covered unisys publication 3850 7802 instruction processor programming reference manual also see univac 1100/2200 series 1100 series used 36-bit word 6-bit characters since 1962 word character size department defense dod requirement since military needed able calculate accurate trajectories design bridges perform engineering scientific calculations needed 32 bits precision 32-bit floating point number provided 6 digits accuracy 36 bit number provided 8 digits accuracy accepted minimum requirement since memory storage space costs drove system going 64 bits simply acceptable general systems use ones complement arithmetic unusual time almost computer manufacturers time delivered 36-bit systems 6-bit characters including ibm dec general electric sylvania 6-bit character set used 1100 series also dod mandated set defined army signal corps called fieldata data returned field 1108 provided 9-bit character format order support ascii later iso 8-bit sets extensively used 1980s space constraints 2200 series architecture provides many registers base registers logically contain virtual address points word code data bank segment may point beginning bank word within bank index registers used instructions modify offset specified assumed base register simple arithmetic add subtract may performed index registers addition index registers consist lower offset portion upper increment portion instruction may use offset value index register part address specify increment added offset allows loops accomplished fewer instructions incrementing index step size accomplished without separate instruction arithmetic registers allow full set computational instructions including floating point operations instructions work adjacent pairs registers perform double-precision operations even-odd constraints two registers may used double-precision value four arithmetic registers also index registers sets overlap – index register x12 arithmetic register a0 allows full range calculations performed indexes without move results rest registers known r registers used fast temporary storage certain special functions r1 holds repeat count instructions may repeated block transfer execute repeated etc. r2 holds bit mask instructions perform bitwise logical operation addition functions e.g. masked load upper two full sets registers x r b one set user registers used applications portions operating system saved restored part activity thread state set exec registers used interrupt processing routines portions operating system want avoid save restore user registers exec registers writable user applications although user code read result exec carefully designed never leave private secure confidential information registers instruction interpretation chooses appropriate register set use based bit processor state register bit always set changed privileged interrupt registers also visible address space exec portion protected reference non-privileged code result fault interrupt 2200 series uses 36-bit segmented virtual address space ’ look later addressing architecture 2200 series cisc architecture system large number instructions current count 245 many addressing variants variants encoded directly instruction format partial word references dependent processor state register settings many instructions also perform complex functions one implements large part cobol edit verb figure shows building blocks architecture data comm two primary examples software subsystems live protection ring user application exec many subsystems users write mentioned earlier 2200 series uses 36-bit segmented virtual address original notion segmented space came earliest implementation emphasized code data separation performance use shared code banks years expanded provide greater flexibility levels sharing far greater protection security reliability controlled access shared data also introduced virtual address consists three parts high-order 3 bits define sharing level heart entire addressing protection scheme every thread eight bank descriptor tables segment descriptor tables industry based b16-b23 tables indexed level – level 0 refers bank descriptor table bdt based b16 level 2 bdt based b18 etc level 0 level 2 bdts common threads system every run process level 4 bdt bdt common threads run every user thread unshared level 6 bdt extended-mode activity thread always six banks segments totally unique one return control stack holds information calling structure including security relevant privilege state changes accessible thread except use call return similar instructions major part protection reliability mechanism applications cause bad effects changing return addresses overwriting return control stack another unique bank automatic storage bank activity local store stack used compilers hold local variables created within block also used hold parameter lists passed call one checks made operating system behalf call made protected subsystem ensure operands thread-local stack thread right access memory region referenced parameters parameters kept thread-local space chance thread may change validation responsibility called procedure perform similar checks secondary parameters may exist shared space i.e. primary parameter points structure contains pointers procedure expected copy pointers local space validating use internally held validated pointer activities may create additional segments limit available address space 2 words 8gw 36gb convenient way multi-threaded applications get large amounts memory space knowing totally thread-safe taking space away rest available program activity program independent space meaning application say 100 activities able use 800gw 3tb virtual space basic-mode activities start banks basic-mode programs aware virtual address space calls extended-mode subsystems cause banks created os 2200 implement programs exactly way unix linux windows implement processes closest analogy obvious difference os 2200 permits single program per run job session executing time program may hundreds threads spawn programs run concurrently several banks program level contain mixture run job session information program information control structures operating system access read-only access program programs may retrieve information structures debugging purposes retrieve things like user-id terminal-id without overhead system call written program contain things like thread state save areas file control blocks accounting information rest banks used program program object file executed operating system obtains bank information file creates banks needed loads bank initial state file simplest program single bank containing code data considered bad form permitted compatibility old applications create application assembly language standard compilers create one code banks one data banks normally code banks marked read-only debugging reliability aid security concerns either way program affect program thus address space distinct programs system nothing program change contents program ’ memory os shared subsystems protected mechanisms discussed later even read access prohibited os subsystem memory almost cases code program possible create shared subsystem generally readable even writable multiple programs must explicitly installed way privileged system administrator programs initially created banks specified object file single activity may use system calls create additional banks within program level additional activities closest analogy shared subsystem .dll subsystem much like program many respects except activities associated instead accessed programs subsystems typically via call instruction fact program subsystem plus one activities every activity belongs home subsystem program created subsystem concept important encapsulation access rights privilege within home subsystem activities typically share common access rights code data banks code banks home subsystem usually read-only even execute-only contain constant data activities right execute subsystems also combinations banks may contain data banks well code banks globally shared subsystems must installed system someone appropriate administrator privileges subsystems may also open files database manager subsystem opens database files use typically exclusive access rights operating system attach banks subsystem hold file control tables os level contains banks exec banks never directly accessible either programs global subsystems entry points os handled way protected subsystem calls made os always via gates instructions exist purpose er executive request via interrupts next part virtual address bdi bank descriptor index level field selected particular bank descriptor table base register b16-b23 base registers b16-b23 part activity state maintained exec direct access activity bank descriptor tables program activity levels exist within program-level banks belong operating system bdi simply index bank descriptor table entry table contains information bank entry describes 1mb 256kw virtual address space larger contiguous space needed consecutive entries logically combined create larger bank maximum 2 words bank descriptor table entry bank descriptor – bd gives size bank small 256kw large 16mw large 1gw small bank always represented single bd large banks represented 64 consecutive bds large bank 4096 bds large large banks need use 64 4096 consecutive bds use many needed provide virtual address space required entry also contains upper lower limits allowable offsets within bank virtual addresses outside limits generate fault interrupt allows small banks example containing message virtual space reserved actually needs provides debugging check bad pointers indices bd also contains key value access control fields fields indicate whether read write execute permission granted instruction processor 3 bits special access permissions sap applies activities executing within owning subsystem really matching key value general access permissions gap applies everyone else usually zero access exec sets key value state activity may changed gate interrupt transitions 2200 series protection architecture uses three pieces activity state reflected hardware state processor privilege pp ring domain processor privilege controls ability execute privileged instructions access protected registers state pp=0 used exec gives full access instructions privileged state exec activities user activities used gate access exec api run pp=0 pp=1 restricts privileged instructions allow reading day clocks reading contents privileged registers none privileged registers contain truly sensitive information allowing general read access could easily lead undetected errors user programs basically pp=1 instructions change addressing environment change clocks change instrumentation state perform i/o restricted pp=1 rarely used pp=2 normal user mode state code executes restriction pp=1 also pp=3 restricts instructions user program execute currently use many existing programs using instructions intent restrict access instructions may system model dependent domain mechanism heart protection mechanism bd bank descriptor lock field consisting ring number domain number also key field state activity key matches lock ring key less ring lock activity special access permission otherwise activity general access permission ring allows overriding domain protection mechanism user applications run ring=3 protected subsystems run ring=2 gives access data still allowing access parameters data calling user ’ space note still possible thread cause protected subsystem access user ’ space thread ’ bank descriptor tables use ring=0 used os allows access data still able access parameters passed either user programs protected subsystems gates another part protection mechanism gate data structure controls transitions domains gate lives gate bank hardware enforces references gates must addresses proper offset multiple gate size within gate bank gate contains target address new values pp ring domain may contain hidden parameter passed target protected subsystems directly accessible subsystems instead subsystem must request gate built gate bank access subsystem permits operating system perform access control checks linking system find gate address associated entry point fact whole mechanism usually transparently handled within linking system hidden parameter permits example file i/o gate contain address handle file control block since guaranteed correct created os user opened file many error checks eliminated path length i/o os 2200 designed handle 32 instruction processors cpus great deal design done years optimize environment example os 2200 makes almost use critical sections design ’ high probability multiple processors executing code instead uses data locking finest granularity data possible generally locks deal single instance data object e.g. activity control structure file control block contained within data structure object minimizes likelihood conflicts global locks set updating list objects lock set long takes update links list even dispatching done separate locks different priority levels check made empty priority level without setting lock lock need set adding removing item queue register set visible address space registers appear exist first 128 words 200 current instruction bank b0 referenced data item impose restriction compilers place data constants first 128 words code bank result expansion instruction set without requiring additional operation codes register-to-register operations accomplished register-storage operation codes typical instructions contain function code target source register index register base register displacement field function code qualifier indicates immediate data displacement base h fields combine form single 18-bit immediate value allows loading adding multiplying etc small constants eliminate memory reference associated storage processor state captured stack interrupt contains information needed return control interrupted activity determine type interrupt interrupts may occur middle long instructions state deals possibility basic mode another whole form instruction formats addressing basic mode provides compatibility previous systems back 1108 practical purposes hardware architecture defines rules addresses instructions converted forms obvious difference basic mode lack explicit b registers instructions instead four implicitly used b registers b12-b15 complex algorithm using limits banks represented b registers operand address b register within current instruction found interesting instructions 2200 repertoire locking synchronization instructions conditional replace familiar quite similar compare swap intel architecture instructions always gain exclusive use memory/cache-line holding referenced word ts tss check bit referenced word bit clear set continue ts skip tss bit set either interrupt ts fall next instruction tss ts interrupt os takes one several actions depending instruction sequence activity priority real time exec activities simply get control back allow retry unless even higher-priority activity waiting presumption lock set another processor soon cleared user activity running real time priority may priority temporarily reduced placed back dispatching queues alternatively code sequence may indicate test set queuing used case os places activity wait state chains end list activities waiting particular lock activities clearing lock check see waiting notify os allow one try test set queuing typically used synchronization within subsystems database manager activities many programs may executing result mechanisms efficient low overhead synchronization among activities queuing architecture another interesting special case specifically designed allow efficient handling messaging number messages waiting processing could almost unlimited also aimed reducing one primary costs messaging namely constantly move messages around memory even moving communication manager message queue subsystem processing program eliminated instead message placed small bank instructions allow placing bank descriptors banks queue removing queue message placed queue sending program subsystem longer access bank removed address space message retrieved queue bank becomes part receiver address space queuing instructions also provide activity synchronization functions e.g. wait message pointers moved moved way ensures security integrity moved data message visible recipient i/o 2200 series systems handled i/o processors processors offload large portions i/o path length recovery fully isolating main system i/o faults interrupts bus errors etc greatly improve reliability availability i/o processors come three different types storage communications clustering real difference firmware load i/o processors controlled operating system os 2200 provide raw mode i/o called arbitrary device i/o even os validates program accessing allowed device handles interrupts faults passing appropriate status program programs must granted privileges security officer access devices arbitrary mode may limited security officer system operator specific devices arbitrary i/o allowed device also use program system device must exclusively allocated program os takes general calls programs generates command packets real memory device addresses passed i/o processor firmware i/o processor actually creates device specific e.g. scsi packets sets dma issues i/o services interrupts
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Computer architecture
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ansarada ansarada provider ai-powered virtual data rooms material information platforms business transactions material events mergers acquisitions fundraising tenders ipos historically ansarada virtual data rooms enabled hosting exchange management confidential material information bidders sellers mergers acquisitions due diligence process software service saas solutions ansarada also creators world first video game since launched january 2014 138,000 sessions total screen views amounting 9.5 million ansarada offices sydney london new york chicago well employees working asia africa continental europe sydney-based ansarada founded 2005 andrew slavin chief technology officer sam riley chief executive rachel riley chief financial officer daphne chang company named first two letters founder first names four founders employees continue 80 percent company group investment bankers lawyers owning remaining 20 percent ansarada disclose sales profits ansarada claims 60 percent market share australian deals employs 200 people offices sydney chicago new york city london amsterdam frankfurt johannesburg hong kong development centre ho chi minh city july 2016 ansarada partnered pyco group launched new software development center vietnam range artificial intelligence features introduced ansarada virtual data rooms vdr 2017 ai-powered alternative traditional virtual data rooms 100-plus new features allow users “ illuminate risk opportunity raise protect potential optimize processes deal preparation execution close ” sell-side users ansarada rooms view ai bidder engagement score assigns numerical value likelihood potential bidder make offer predicts win objectively tells sellers interest ai bidder engagement score calculated using machine learning algorithm takes account performance 57 separate metrics time aida acronym ansarada intelligent data assistant extracts on-demand insights data based activity within ansarada room allows information accessed natural language need login click menus features desktop product users interact aida chat interface available iphone itunes app store virtual assistant uses natural language processing understand user requests plus 20 “ skills ” extract data insights provide answers october 2017 ansarada launched world first material information platform deliver readiness service raas platform uses new technologies artificial intelligence machine learning help businesses ready important outcomes structuring material information correctly assigning accountability people tracking progress objective score readiness selection ansarada clients include law firms corporate finance software property private equity venture capital ansarada launched game january 2014 appeal primarily investment bankers looking express competitive sides risk-free setting new york times reported ten hours games release attracted 1,000 users played 3,300 times according new york times
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Distributed computing architecture
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arm cortex-a55 arm cortex-a55 microarchitecture implementing armv8.2-a 64-bit instruction set designed arm holdings cambridge design centre cortex-a55 2-wide decode in-order superscalar pipeline cortex-a55 serves successor arm cortex-a53 designed improve performance energy efficiency a53 arm stated a55 15 improved power efficiency 18 increased performance relative a53 memory access branch prediction also improved relative a53 cortex-a75 cortex-a55 cores first products support arm dynamiq technology successor big.little technology designed flexible scalable designing multi-core products cortex-a55 available sip core licensees design makes suitable integration sip cores e.g gpu display controller dsp image processor etc one die constituting system chip soc arm also collaborated qualcomm semi-custom version cortex-a55 used within kryo 385 cpu core semi-custom core also used qualcomm mid-range socs kryo 360 silver kryo 460 silver
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Computer architecture
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arm cortex-a75 arm cortex-a75 microarchitecture implementing armv8.2-a 64-bit instruction set designed arm holdings sophia design centre cortex-a75 3-wide decode out-of-order superscalar pipeline cortex-a75 serves successor cortex-a73 designed improve performance a73 maintaining efficiency according arm a75 expected offer 16–48 better performance a73 targeted beyond mobile workloads a75 also features increased tdp envelope 2 w enabling increased performance cortex-a75 cortex-a55 cores first products support arm dynamiq technology successor big.little technology designed flexible scalable designing multi-core products cortex-a75 available sip core licensees design makes suitable integration sip cores e.g gpu display controller dsp image processor etc one die constituting system chip soc arm also collaborated qualcomm semi-custom version cortex-a75 used within kryo 385 cpu semi-custom core also used qualcomm mid-range socs kryo 360 gold
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Computer architecture
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device configuration overlay device configuration overlay dco hidden area many today ’ hard disk drives hdds usually information stored either dco host protected area hpa accessible bios os user however certain tools used modify hpa dco system uses identify_device command determine supported features given hard drive dco report command supported features nonexistent drive smaller actually determine actual size features disk device_configuration_identify command used output command compared output identify_device see dco present given hard drive major tools remove dco order fully image hard drive using device_configuration_reset command permanently alters disk unlike host protected area hpa temporarily removed power cycle device configuration overlay dco first introduced ata-6 standard allows system vendors purchase hdds different manufacturers potentially different sizes configure hdds number sectors example would using dco make 80-gigabyte hdd appear 60-gigabyte hdd os bios ... given potential place data hidden areas area concern computer forensics investigators additional issue forensic investigators imaging hdd hpa and/or dco certain vendors claim tools able properly detect image hpa either silent handling dco indicate beyond capabilities tool hdat2 free software program ms-dos used create/remove host protected area hpa using command set max create/remove dco hidden area using command dco modify also functions dco data synergy freeware atatool utility used detect dco windows environment recent versions allow dco created removed frozen guidance software encase comes linux-based tool images hard drives called linen linen 6.01 validated national institute justice nij october 2008 found tool remove either host protected areas hpas dcos however linux test environment automatically removed hpa test drive allowing tool image sectors hidden hpa tool acquire sectors hidden dco accessdata ftk imager 2.5.3.14 validated national institute justice nij june 2008 findings indicated physical acquisition made drive hidden sectors either host protected area device configuration overlay tool remove either hpa dco tool acquire sectors hidden hpa variety hardware imaging tools found successfully detect remove dcos nij routinely tests digital forensics tools publications found http //nij.ncjrs.gov/app/publications/pub_search.aspx searchtype=basic category=99 location=top psid=55 nist https //www.nist.gov/itl/ssd/cs/cftt/cftt-disk-imaging.cfm
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Computer security
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compaq evo compaq evo series business desktop laptop pcs thin clients made compaq hewlett-packard following 2002 merger evo brand introduced compaq may 2001 business-oriented brand replaced compaq deskpro brand desktops armada notebooks evo rebranded hp compaq used 2013 desktops small made positioned horizontally instead vertically monitor could placed top save space featured sleek silver black compact design early models shipped cd-rom drives compaq eventually shipped evo cd-rw drives dvd-rom drives design models allowed one cd dvd drive models bigger designs 2 cd dvd drives models also shipped 3½ floppy drive positioned cd dvd drive models also 2 usb 2.0 ports front convenience well two back human interface devices external volumes also headphone microphone jack front line line back laptops conservative design described one reviewer old-school black squared-off-corner business notebook models tough black case reminiscent ibm thinkpad midsize 14 15 screen good multimedia capability offered 256 mb ram standard amount easily upgraded 512 mb even 1 gb thin clients based geode processor family compaq evo desktop computer great option businesses schools compact cheap design affordable needed specs businesses schools compaq evo computers shipped standard windows xp windows 2000 running compaq evo shipped pentium 4 processors laptop evos shipped centrino platforms last evo-branded models released 2003 later replaced re-branded like compaq-branded products hp compaq products final model carry compaq evo name n620c notebook early pentium-m system featured 1.6ghz processor n620c intel centrino-based instead used compaq wireless module snapped onto multiport slot lid notebook desktop models notebook models thin clients
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Computer architecture
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risk management framework risk management framework united states federal government policy standards help secure information systems computers networks developed national institute standards technology two main publications cover details rmf nist special publication 800-37 guide applying risk management framework federal information systems nist special publication 800-53 security privacy controls federal information systems organizations nist special publication 800-37 guide applying risk management framework federal information systems developed joint task force transformation initiative working group transforms traditional certification accreditation c process six-step risk management framework rmf risk management framework rmf illustrated right provides disciplined structured process integrates information security risk management activities system development life cycle rmf steps include lifecycle information system encounter many types risk affect overall security posture system security controls must implemented rmf process supports early detection resolution risks risk categorized high level infrastructure risks project risks application risks information asset risks business continuity risks outsourcing risks external risks strategic risks infrastructure risks focus reliability computers networking equipment project risks focus budget timeline system quality application risks focus performance overall system capacity information asset risks focus damage loss disclosure unauthorized part information assets business continuity risks focus maintaining reliable system maximum up-time outsourcing risks focus impact 3rd party supplier meeting requirements external risks items outside information system control impact security system strategic risks focuses need information system functions align business strategy system supports
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Computer security
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dynamic synchronous transfer mode dynamic synchronous transfer mode dtm optical networking technology standardized european telecommunications standards institute etsi 2001 beginning specification etsi es 201 803-1 dtm time division multiplexing circuit-switching network technology combines switching transport designed provide guaranteed quality service qos streaming video services used packet-based services well marketed professional media networks mobile tv networks digital terrestrial television dtt networks content delivery networks consumer oriented networks triple play networks dtm architecture conceived 1985 developed royal institute technology kth sweden published february 1996 research team split two spin-off companies reflecting two different approaches use technology one companies remains active field delivers commercial products based dtm technology name net insight
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Internet protocols
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foomatic foomatic configurable printing filter uses ppd files configuration generate appropriate output given printer spooler independent means used common unix printing system cups lprng others uses ghostscript background using options according ppd file printer currently developed openprinting workgroup linux foundation like cups foomatic supposes applications produce output postscript output spools postscript printer action needed otherwise generic way act foomatic-rip knows available printer translate postscript data directly printer language without creating intermediate raster file components package following free drivers specifically developed work foomatic
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Operating systems
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blued macos blued bluetooth daemon macos previously mac os x started system interacted directly user daemon handles service discovery link key management incoming connection acceptance
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Operating systems
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creative basic creative basic cb third-generation event-driven programming language windows integrated development environment ide current version executables interpreted require runtime libraries installed end-user computer planned future version compiled executables creative basic extensive command set access application programming interface api libraries available microsoft windows operating system although modern version dates 2007 development completely compatible ibasic use worldwide since 2002 notable projects jerry muelver wikiwriter wikiwriter chm wizard alyce watson mike rainey manufacturing engineering programs see links hello program program open console window print 10 random numbers program create gui window exit button event handling routine
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Programming language topics
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dot hill systems dot hill systems corp manufacturer computer storage area network arrays providing computer hardware software products small large computer data storage systems dot hill started 1997 carlsbad california 2004 dot hill acquired chaparral network storage longmont colorado chaparral network storage started 2000 also manufactured storage systems 2010 dot hill start moving almost carlsbad operations longmont dot hill listed nasdaq hill dot hill products interfaces supporting fibre channel fc internet small computer systems interface iscsi serial attached scsi sas products include hard drives solid-state drives ssds dot supports raid software data center storage management applications run windows linux rhel suse apple mac os x snow leopard oracle solaris xenserver vmware esx servers host interfaces ssd sas sata drive technologies seagate technology finalized acquisition company october 2015
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Computer file systems
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crackme crackme often abbreviated cm small program designed test programmer reverse engineering skills programmed reversers legal way crack software since intellectual property infringed upon crackmes reversemes keygenmes generally similar protection schemes algorithms found proprietary software however due wide use packers/protectors commercial software many crackmes actually difficult algorithm harder find track commercial software keygenme specifically designed reverser find protection algorithm used application also write small keygen programming language choice keygenmes properly manipulated self-keygenning example checking might generate corresponding key simply compare expected entered keys makes easy copy key generation algorithm often anti-debugging anti-disassemble routines used confuse debuggers make disassembly useless code-obfuscation also used make reversing even harder
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Computer security
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2014 russian hacker password theft 2014 russian hacker password theft alleged hacking incident resulting possible theft 1.2 billion internet credentials including usernames passwords hundreds millions corresponding e-mail addresses data breach first reported new york times reported many media allegedly discovered reported milwaukee-based information security company hold security 420,000 websites reported affected according new york times source big companies know user credentials among stolen hold security disclose sites compromised instead offered two separate services one website owners one consumers check 're affected service website owners costs 10 month check consumers free hold security described group responsible hack small group “ fewer dozen men 20s ... based small city south central russia region flanked kazakhstan mongolia ” dubbed group cybervor russian lit cyber thief hold claimed hack perpetrated use sql injection according forbes article hold security says 1.2 billion credentials stolen way also ones cybervor simply bought people used means hold security n't know split forbes columnist kashmir hill noted internet predictably panicked story yet another massive password breach went viral pretty direct link panic pay-out security firm hold security website service offering people check username password pair stolen requires people send hold security encrypted versions passwords named independent sources come forward confirm breach forbes columnist joseph steinberg even expressed outright skepticism many facts claimed breach raising questions trustworthiness reports breach altogether
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Computer security
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alan perlis alan jay perlis april 1 1922 – february 7 1990 american computer scientist professor purdue university carnegie mellon university yale university best known pioneering work programming languages first recipient turing award perlis born jewish family pittsburgh pennsylvania graduated taylor allderdice high school 1939 1943 received bachelor degree chemistry carnegie institute technology later renamed carnegie mellon university world war ii served u.s. army became interested mathematics earned master degree 1949 ph.d. 1950 mathematics massachusetts institute technology mit doctoral dissertation titled integral equations solution iteration analytic continuation 1952 participated project whirlwind joined faculty purdue university 1956 moved carnegie institute technology chair mathematics first head computer science department 1962 elected president association computing machinery awarded inaugural turing award 1966 according citation influence area advanced programming techniques compiler construction reference work done member team developed programming language algol 1971 perlis moved yale university become chair computer science hold eugene higgins chair 1977 elected national academy engineering 1982 wrote article epigrams programming association computing machinery acm sigplan journal describing one-sentence distillations many things learned programming career epigrams widely quoted remained yale death 1990 publications selection
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Programming language topics
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activejdbc activejdbc java implementation active record design pattern developed igor polevoy inspired activerecord orm ruby rails based convention configuration similar ruby rails activejdbc infers meta data database result models require setters getters creation saving new records table one line updating existing record activejdbc query language search criteria written abbreviated sql activejdbc general purpose java orm served first building block activeweb
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Programming language topics
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syncback syncback software allows backing synchronizing files several resources including internal external drive different media usb thumb drive cd dvd remote server nas ftp windows server cloud storage provider governing law shall governed laws singapore file backup move sync restore functions program highly rated easy use features found syncback note features may available higher variants syncback four versions syncback available syncbackfree syncbacklite shareware syncbackse shareware syncbackpro shareware syncbackse syncbackpro work windows client versions windows server oses syncbackfree syncbacklite support windows client versions
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Computer security
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mandiant mandiant american cybersecurity firm rose prominence february 2013 released report directly implicating china cyber espionage december 30 2013 mandiant acquired fireeye stock cash deal worth excess 1 billion kevin mandia former united states air force officer serves company chief executive officer founded mandiant red cliff consulting 2004 prior rebranding 2006 2011 mandiant received funding kleiner perkins caufield byers expand staff grow business-to-business operations mandiant provides incident response general security consulting along incident management products major global organizations governments fortune 100 companies 2012 revenues 100 million 76 2011 company acquired fireeye december 30 2013 mandiant awarded 2012 2013 sc award exemplary professional leadership information-technology security mandiant creator openioc open indicators compromise extensible xml schema description technical characteristics identify threats attackers methodologies evidence compromise february 18 2013 mandiant released report documenting evidence cyber attacks people liberation army specifically pudong-based pla unit 61398 targeting least 141 organizations united states english-speaking countries extending far back 2006 report mandiant refers espionage unit apt1 report states likely unit 61398 source attacks video uploaded youtube demonstrating one intrusion apt
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Computer security
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rank computer programming computer programming rank specifications usually synonym refers number dimensions thus two-dimensional array rank two three-dimensional array rank three strictly formal definition provided applies every programming language since concepts semantics terminology term may even applicable contrary applied specific meaning context given language case apl notion applies every operand dyads binary functions left rank right rank box instead shows rank type rank array expression could defined semi-formal style c++ illustrates simple way calculate compile time given code rank type calculated compile time shorter form calculating rank expression done using
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Programming language topics
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fbi cyber division fbi cyber division federal bureau investigation division heads national effort investigate prosecute internet crimes including cyber based terrorism espionage computer intrusions major cyber fraud division fbi uses information gathers investigation inform public current trends cyber crime.federal bureau investigation focuses around three main priorities computer intrusion identity theft cyber fraud created 2002 high priority given investigations involve terrorist organizations intelligence operations sponsored foreign governments fbi calls national security cyber intrusions cyber division primary responsibility fbi efforts counter national security–related cyber intrusions cyber division priorities rank order fbi cyber division works national cyber investigative joint task force ncijtf cyber investigative squads located fbi field office since 2008 ncijtf primary american agency responsible coordinating cyber threats investigations liaisons central intelligence agency cia department defense dod department homeland security dhs national security agency nsa large number cases investigated cyber division come internet fraud complaint center ifcc 2002 received 75,000 complaints cases cyber division investigated included dismantling ring criminals using malware redirect users rogue dns servers operation ghost click taking botnet based coreflood trojan used fraud taking group responsible robbing 2,000 atm machines taking group 100 involved phishing operation phish phry taking darkmarket cyber crime forum used criminals
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Computer security
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concurrent ml concurrent ml cml concurrent extension standard ml programming language characterized ability allow programmers create composable communication abstractions first class rather built language design cml primitive operations adopted several programming languages gnu guile racket manticore many programming languages support concurrency offer communication channels allow exchange values processes threads running concurrently system communications established processes may follow specific protocol requiring programmer write functions establish required pattern communication meanwhile communicating system often requires establishing multiple channels multiple servers choosing available channels new data available accomplished using polling select operation unix systems combining application-specific protocols multi-party communication may complicated due need introduce polling checking blocking within pre-existing protocol concurrent ml solves problem reducing coupling programming concepts introducing synchronizable events events first-class abstraction used synchronization operation called codice_1 cml racket order potentially block produce value resulting communication example data transmitted channel cml events combined manipulated using number primitive operations primitive operation constructs new event rather modifying event in-place allows construction compound events represent desired communication pattern example cml allows programmer combine several sub-events order create compound event non-deterministically chooses one sub-events another primitive creates new event modify value resulting synchronization original event events embody patterns communication non-cml language would typically handled using polling loop function handlers kind event sample code print hello world console spawns thread creates channel strings thread spawns another thread prints first string received channel former thread sends hello world\n string channel uses sml/nj cml note heap name different non linux-x86 platforms may need change line cml_test.x86-linux something different library structure hello
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Programming language topics
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computational linguistics computational linguistics interdisciplinary field concerned statistical rule-based modeling natural language computational perspective well study appropriate computational approaches linguistic questions traditionally computational linguistics performed computer scientists specialized application computers processing natural language today computational linguists often work members interdisciplinary teams include regular linguists experts target language computer scientists general computational linguistics draws upon involvement linguists computer scientists experts artificial intelligence mathematicians logicians philosophers cognitive scientists cognitive psychologists psycholinguists anthropologists neuroscientists among others computational linguistics theoretical applied components theoretical computational linguistics focuses issues theoretical linguistics cognitive science applied computational linguistics focuses practical outcome modeling human language use association computational linguistics defines computational linguistics computational linguistics often grouped within field artificial intelligence actually present development artificial intelligence computational linguistics originated efforts united states 1950s use computers automatically translate texts foreign languages particularly russian scientific journals english since computers make arithmetic calculations much faster accurately humans thought short matter time could also begin process language computational quantitative methods also used historically attempted reconstruction earlier forms modern languages subgrouping modern languages language families earlier methods lexicostatistics glottochronology proven premature inaccurate however recent interdisciplinary studies borrow concepts biological studies especially gene mapping proved produce sophisticated analytical tools trustworthy results machine translation also known mechanical translation failed yield accurate translations right away automated processing human languages recognized far complex originally assumed computational linguistics born name new field study devoted developing algorithms software intelligently processing language data term computational linguistics first coined david hays founding member association computational linguistics international committee computational linguistics artificial intelligence came existence 1960s field computational linguistics became sub-division artificial intelligence dealing human-level comprehension production natural languages order translate one language another observed one understand grammar languages including morphology grammar word forms syntax grammar sentence structure order understand syntax one also understand semantics lexicon 'vocabulary even something pragmatics language use thus started effort translate languages evolved entire discipline devoted understanding represent process natural languages using computers nowadays research within scope computational linguistics done computational linguistics departments computational linguistics laboratories computer science departments linguistics departments research field computational linguistics aims create working speech text processing systems others aim create system allowing human-machine interaction programs meant human-machine communication called conversational agents computational linguistics performed experts variety fields wide assortment departments research fields broach diverse range topics following sections discuss literature available across entire field broken four main area discourse developmental linguistics structural linguistics linguistic production linguistic comprehension language cognitive skill develops throughout life individual developmental process examined using number techniques computational approach one human language development provide constraints make harder apply computational method understanding instance language acquisition human children largely exposed positive evidence means linguistic development individual evidence correct form provided evidence correct insufficient information simple hypothesis testing procedure information complex language provides certain boundaries computational approach modeling language development acquisition individual attempts made model developmental process language acquisition children computational angle leading statistical grammars connectionist models work realm also proposed method explain evolution language history using models shown languages learned combination simple input presented incrementally child develops better memory longer attention span simultaneously posed reason long developmental period human children conclusions drawn strength artificial neural network project created ability infants develop language also modeled using robots order test linguistic theories enabled learn children might model created based affordance model mappings actions perceptions effects created linked spoken words crucially robots able acquire functioning word-to-meaning mappings without needing grammatical structure vastly simplifying learning process shedding light information furthers current understanding linguistic development important note information could empirically tested using computational approach understanding linguistic development individual within lifetime continually improved using neural networks learning robotic systems also important keep mind languages change develop time computational approaches understanding phenomenon unearthed interesting information using price equation pólya urn dynamics researchers created system predicts future linguistic evolution also gives insight evolutionary history modern-day languages modeling effort achieved computational linguistics would otherwise impossible clear understanding linguistic development humans well throughout evolutionary time fantastically improved advances computational linguistics ability model modify systems affords science ethical method testing hypotheses would otherwise intractable order create better computational models language understanding language structure crucial end english language meticulously studied using computational approaches better understand language works structural level one important pieces able study linguistic structure availability large linguistic corpora samples grants computational linguists raw data necessary run models gain better understanding underlying structures present vast amount data contained single language one cited english linguistic corpora penn treebank derived widely-different sources ibm computer manuals transcribed telephone conversations corpus contains 4.5 million words american english corpus primarily annotated using part-of-speech tagging syntactic bracketing yielded substantial empirical observations related language structure theoretical approaches structure languages also developed works allow computational linguistics framework within work hypotheses understanding language myriad ways one original theoretical theses internalization grammar structure language proposed two types models models rules patterns learned increase strength frequency encounter work also created question computational linguists answer infant learn specific non-normal grammar chomsky normal form without learning overgeneralized version getting stuck theoretical efforts like set direction research go early lifetime field study crucial growth field structural information languages allows discovery implementation similarity recognition pairs text utterances instance recently proven based structural information present patterns human discourse conceptual recurrence plots used model visualize trends data create reliable measures similarity natural textual utterances technique strong tool probing structure human discourse without computational approach question vastly complex information present discourse data would remained inaccessible scientists information regarding structural data language available english well languages japanese using computational methods japanese sentence corpora analyzed pattern log-normality found relation sentence length though exact cause lognormality remains unknown precisely sort intriguing information computational linguistics designed uncover information could lead important discoveries regarding underlying structure japanese could number effects understanding japanese language computational linguistics allows exciting additions scientific knowledge base happen quickly little room doubt recent days structural data languages available several languages world english language computational linguistics work progress sindhi language structure grammar domain sindhi language different languages world computational linguistics models english language suitable sindhi language viewing computational linguistics work sindhi language started properly developing methods algorithms linguistics tools https //sindhinlp.com/ machine learning models deep learning models since 2016. focus solve linguistics problems sindhi language work could lead important discoveries regarding underlying structure sindhi could number effects understanding sindhi language computational linguistics allows exciting additions scientific knowledge base happen quickly little room doubt without computational approach structure linguistic data much information available would still hidden vastness data within single language computational linguistics allows scientists parse huge amounts data reliably efficiently creating possibility discoveries unlike seen approaches production language equally complex information provides necessary skills fluent producer must say comprehension half problem communication half system produces language computational linguistics made interesting discoveries area famous paper published 1950 alan turing proposed possibility machines might one day ability think thought experiment might define concept thought machines proposed imitation test human subject two text-only conversations one fellow human another machine attempting respond like human turing proposes subject tell difference human machine may concluded machine capable thought today test known turing test remains influential idea area artificial intelligence projects still trying solve problem first started computational linguistics field first place however methods become refined clever consequently results generated computational linguists become enlightening effort improve computer translation several models compared including hidden markov models smoothing techniques specific refinements apply verb translation model found produce natural translations german french words refined alignment model first-order dependence fertility model 16 also provide efficient training algorithms models presented give scientists ability improve results type work specific computational linguistics applications could vastly improve understanding language produced comprehended computers work also done making computers produce language naturalistic manner using linguistic input humans algorithms constructed able modify system style production based factor linguistic input human abstract factors like politeness five main dimensions personality work takes computational approach via parameter estimation models categorize vast array linguistic styles see across individuals simplify computer work way making human-computer interaction much natural many earliest simplest models human-computer interaction eliza example involve text-based input user generate response computer method words typed user trigger computer recognize specific patterns reply accordingly process known keyword spotting recent technologies placed emphasis speech-based interactive systems systems siri ios operating system operate similar pattern-recognizing technique text-based systems former user input conducted speech recognition branch linguistics involves processing user speech sound waves interpreting acoustics language patterns order computer recognize input much focus modern computational linguistics comprehension proliferation internet abundance easily accessible written human language ability create program capable understanding human language would many broad exciting possibilities including improved search engines automated customer service online education early work comprehension included applying bayesian statistics task optical character recognition illustrated bledsoe browing 1959 large dictionary possible letters generated learning example letters probability one learned examples matched new input combined make final decision attempts applying bayesian statistics language analysis included work mosteller wallace 1963 analysis words used federalist papers used attempt determine authorship concluding madison likely authored majority papers 1971 terry winograd developed early natural language processing engine capable interpreting naturally written commands within simple rule governed environment primary language parsing program project called shrdlu capable carrying somewhat natural conversation user giving commands within scope toy environment designed task environment consisted different shaped colored blocks shrdlu capable interpreting commands find block taller one holding put box asking questions n't understand pyramid mean response user input impressive kind natural language processing proven much difficult outside limited scope toy environment similarly project developed nasa called lunar designed provide answers naturally written questions geological analysis lunar rocks returned apollo missions kinds problems referred question answering initial attempts understanding spoken language based work done 1960s 1970s signal modeling unknown signal analyzed look patterns make predictions based history initial somewhat successful approach applying kind signal modeling language achieved use hidden markov models detailed rabiner 1989 approach attempts determine probabilities arbitrary number models could used generating speech well modeling probabilities various words generated possible models similar approaches employed early speech recognition attempts starting late 70s ibm using word/part-of-speech pair probabilities recently kinds statistical approaches applied difficult tasks topic identification using bayesian parameter estimation infer topic probabilities text documents modern computational linguistics often combination studies computer science programming math particularly statistics language structures natural language processing combined fields often lead development systems recognize speech perform task based speech examples include speech recognition software apple siri feature spellcheck tools speech synthesis programs often used demonstrate pronunciation help disabled machine translation programs websites google translate computational linguistics especially helpful situations involving social media internet example filters chatrooms website searches require computational linguistics chat operators often use filters identify certain words phrases deem inappropriate users submit another example using filters websites schools use filters websites certain keywords blocked children view also many programs parents use parental controls put content filters place computational linguists also develop programs group organize content social media mining example twitter programs group tweets subject keywords computational linguistics also used document retrieval clustering online search documents websites retrieved based frequency unique labels related typed search engine instance search red large four-wheeled vehicle intention finding pictures red truck search engine still find information desired matching words four-wheeled car computational linguistics divided major areas depending upon medium language processed whether spoken textual upon task performed whether analyzing language recognition synthesizing language generation speech recognition speech synthesis deal spoken language understood created using computers parsing generation sub-divisions computational linguistics dealing respectively taking language apart putting together machine translation remains sub-division computational linguistics dealing computers translate languages possibility automatic language translation however yet realized remains notoriously hard branch computational linguistics areas research studied computational linguistics include subject computational linguistics recurring impact popular culture
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Computational linguistics
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vinum volume manager vinum logical volume manager also called software raid allowing implementations raid-0 raid-1 raid-5 models individually combination original vinum part base distribution freebsd operating system since 3.0 also netbsd 2003-10-10 2006-02-25 well descendants freebsd including dragonfly bsd recent versions freebsd replaced gvinum first introduced around freebsd 6 vinum source code maintained freebsd dragonfly source trees vinum supports raid levels 0 1 5 jbod vinum inspired veritas volume manager vinum invoked codice_1 geom vinum freebsd version 5.4 modern freebsd may considered legacy volume manager modern alternatives geom zfs netbsd removed netbsd 4.0 due lack interest maintenance raidframe cited providing similar functionality dragonfly bsd dragonfly hammer filesystem already implements network mirroring codice_2 utility could used configure codice_2 another software raid implementation originally appeared freebsd 6.0 codice_2 deprecated freebsd 9 removed freebsd 10.0 netbsd port red hat lvm2 also available base system dragonfly well addition vinum distribution data across multiple disks managed either dedicated hardware software additionally hybrid raids partly software- partly hardware-based solutions software implementation operating system manages disks array normal drive controller ata sata scsi fibre channel etc. present cpu speeds software raid faster hardware raid hardware implementation raid requires minimum special-purpose raid controller desktop system may pci expansion card might capability built motherboard larger raids controller disks usually housed external multi-bay enclosure controller handles management disks performs parity calculations needed many raid levels option tends provide better performance makes operating system support easier hardware implementations also typically support hot swapping allowing failed drives replaced system running rare cases hardware controllers become faulty result data loss hybrid raids become popular introduction inexpensive hardware raid controllers hardware normal disk controller raid features boot-time application allows users set raids controlled via bios modern operating system used need specialized raid drivers make array look like single block device since controllers actually calculations software hardware often called fakeraids unlike software raid fakeraids typically span multiple controllers simple example mirror drive enterprise drive excelsior raid1
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Operating systems
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droidkungfu droidkungfu malware affects android os primarily targets users china first evidence malware found android market march 2011 droidkungfu discovered us-based researchers yajin zhou xuxian jiang two discovered malware working north carolina state university targets android 2.2 platform allows hackers access control devices droidkungfu malware collect user data backdoor hacking droidkungfu encrypts two different root exploits udev exploit rageagainsthecage exploit break android security executed decrypts exploits communicates remote server without user knowledge
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Computer security
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frame relay frame relay standardized wide area network technology specifies physical data link layers digital telecommunications channels using packet switching methodology originally designed transport across integrated services digital network isdn infrastructure may used today context many network interfaces network providers commonly implement frame relay voice vofr data encapsulation technique used local area networks lans wide area network wan end-user gets private line leased line frame relay node frame relay network handles transmission frequently changing path transparent end-user extensively used wan protocols less expensive leased lines one reason popularity extreme simplicity configuring user equipment frame relay network offers another reason frame relay popularity advent ethernet fiber optics mpls vpn dedicated broadband services cable modem dsl end may loom frame relay protocol encapsulation however many rural areas remain lacking dsl cable modem services cases least expensive type non-dial-up connection remains 64-kbit/s frame relay line thus retail chain instance may use frame relay connecting rural stores corporate wan designers frame relay aimed provide telecommunication service cost-efficient data transmission intermittent traffic local area networks lans end-points wide area network wan frame relay puts data variable-size units called frames leaves necessary error-correction retransmission data end-points speeds overall data transmission services network provides permanent virtual circuit pvc means customer sees continuous dedicated connection without pay full-time leased line service-provider figures route frame travels destination charge based usage enterprise select level service quality prioritizing frames making others less important frame relay run fractional t-1 full t-carrier system carriers outside americas e1 full e-carrier frame relay complements provides mid-range service basic rate isdn offers bandwidth 128 kbit/s asynchronous transfer mode atm operates somewhat similar fashion frame relay speeds 155.520 mbit/s 622.080 mbit/s frame relay technical base older x.25 packet-switching technology designed transmitting data analog voice lines unlike x.25 whose designers expected analog signals relatively high chance transmission errors frame relay fast packet switching technology operating links low chance transmission errors usually practically lossless like pdh means protocol attempt correct errors frame relay network detects error frame simply drops frame end points responsibility detecting retransmitting dropped frames however digital networks offer incidence error extraordinarily small relative analog networks frame relay often serves connect local area networks lans major backbones well public wide-area networks wans also private network environments leased lines t-1 lines requires dedicated connection transmission period frame relay provide ideal path voice video transmission require steady flow transmissions however certain circumstances voice video transmission use frame relay frame relay originated extension integrated services digital network isdn designers aimed enable packet-switched network transport circuit-switched technology technology become stand-alone cost-effective means creating wan frame relay switches create virtual circuits connect remote lans wan frame relay network exists lan border device usually router carrier switch technology used carrier transport data switches variable may differ among carriers i.e. function practical frame relay implementation need rely solely transportation mechanism sophistication technology requires thorough understanding terms used describe frame relay works without firm understanding frame relay difficult troubleshoot performance frame-relay frame structure essentially mirrors almost exactly defined lap-d. traffic analysis distinguish frame relay format lap-d lack control field frame relay protocol data unit pdu consists following fields frame relay network uses simplified protocol switching node achieves simplicity omitting link-by-link flow-control result offered load largely determined performance frame relay networks offered load high due bursts services temporary overload frame relay nodes causes collapse network throughput therefore frame relay networks require effective mechanisms control congestion congestion control frame relay networks includes following elements network established connection edge node frame relay network must monitor connection traffic flow ensure actual usage network resources exceed specification frame relay defines restrictions user information rate allows network enforce end user information rate discard information subscribed access rate exceeded explicit congestion notification proposed congestion avoidance policy tries keep network operating desired equilibrium point certain quality service qos network met special congestion control bits incorporated address field frame relay fecn becn basic idea avoid data accumulation inside network fecn means forward explicit congestion notification fecn bit set 1 indicate congestion experienced direction frame transmission informs destination congestion occurred becn means backwards explicit congestion notification becn bit set 1 indicate congestion experienced network direction opposite frame transmission informs sender congestion occurred frame relay began stripped-down version x.25 protocol releasing error-correcting burden commonly associated x.25 frame relay detects error simply drops offending packet frame relay uses concept shared access relies technique referred best-effort whereby error-correction practically exist practically guarantee reliable data delivery occurs frame relay provides industry-standard encapsulation utilizing strengths high-speed packet-switched technology able service multiple virtual circuits protocols connected devices two routers although frame relay became popular north america never popular europe x.25 remained primary standard wide availability ip made packet switching almost obsolete used sometimes backbone services x.25 ip traffic frame relay used usa also carrier tcp/ip traffic europe backbones ip networks often used atm pos later replaced carrier ethernet x.25 provides quality service error-free delivery whereas frame relay designed relay data quickly possible low error networks frame relay eliminates number higher-level procedures fields used x.25 frame relay designed use links error-rates far lower available x.25 designed x.25 prepares sends packets frame relay prepares sends frames x.25 packets contain several fields used error checking flow control used frame relay frames frame relay contain expanded link layer address field enables frame relay nodes direct frames destinations minimal processing elimination functions fields x.25 allows frame relay move data quickly leaves room errors larger delays data need retransmitted x.25 packet switched networks typically allocated fixed bandwidth network x.25 access regardless current load resource allocation approach apt applications require guaranteed quality service inefficient applications highly dynamic load characteristics would benefit dynamic resource allocation frame relay networks dynamically allocate bandwidth physical logical channel level wan protocol frame relay commonly implemented layer 2 data link layer open systems interconnection osi seven layer model two types circuits exist permanent virtual circuits pvcs used form logical end-to-end links mapped physical network switched virtual circuits svcs latter analogous circuit-switching concepts public switched telephone network pstn global phone network initial proposals frame relay presented consultative committee international telephone telegraph ccitt 1984 lack interoperability standardization prevented significant frame relay deployment 1990 cisco digital equipment corporation dec northern telecom stratacom formed consortium focus development produced protocol provided additional capabilities complex inter-networking environments frame relay extensions referred local management interface lmi datalink connection identifiers dlcis numbers refer paths frame relay network locally significant means device-a sends data device-b likely use different dlci device-b would use reply multiple virtual circuits active physical end-points performed using subinterfaces lmi global addressing extension gives frame relay data-link connection identifier dlci values global rather local significance dlci values become dte addresses unique frame relay wan global addressing extension adds functionality manageability frame relay internetworks individual network interfaces end nodes attached example identified using standard address-resolution discovery techniques addition entire frame relay network appears typical lan routers periphery lmi virtual circuit status messages provide communication synchronization frame relay dte dce devices messages used periodically report status pvcs prevents data sent black holes pvcs longer exist lmi multicasting extension allows multicast groups assigned multicasting saves bandwidth allowing routing updates address-resolution messages sent specific groups routers extension also transmits reports status multicast groups update messages frame relay connections often given committed information rate cir allowance burstable bandwidth known extended information rate eir provider guarantees connection always support c rate sometimes pra rate adequate bandwidth frames sent excess cir marked discard eligible de means dropped congestion occur within frame relay network frames sent excess eir dropped immediately frame relay aimed make efficient use existing physical resources permitting over-provisioning data services telecommunications companies customers clients unlikely using data service 45 percent time recent years frame relay acquired bad reputation markets excessive bandwidth overbooking telecommunications companies often sell frame relay businesses looking cheaper alternative dedicated lines use different geographic areas depended greatly governmental telecommunication companies policies early companies make frame relay products included stratacom later acquired cisco systems cascade communications later acquired ascend communications lucent technologies june 2007 inc. largest frame relay service provider usa local networks 22 states plus national international networks multiplexing packet data different virtual circuits flows quality service concerns often arise frame one virtual circuit may occupy line long enough period time disrupt service guarantee given another virtual circuit ip fragmentation method addressing incoming long packet broken sequence shorter packets enough information added reassemble long frame far end frf.12 specification frame relay forum specifies perform fragmentation frame relay traffic primarily voice traffic frf.12 specification describes method fragmenting frame relay frames smaller frames
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Internet protocols
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basic stamp basic stamp microcontroller small specialized basic interpreter pbasic built rom made parallax inc. popular electronics hobbyists since early 1990s although basic stamp 2 form 24 pin dip chip fact small printed circuit board pcb contains essential elements microprocessor system end result hobbyist connect 9 v battery basic stamp complete system serial connection personal computer allows programmer download software basic stamp stored onboard non-volatile memory device remains programmed erased reprogrammed even power stamp removed power reconnected stamp immediately starts executing program slot 0 8 numbered 0..7 basic stamp programmed variant basic language called pbasic pbasic incorporates common microcontroller functions including pwm serial communications i²c 1-wire communications communications common lcd driver circuits hobby servo pulse trains pseudo-sine wave frequencies ability time rc circuit may used detect analog value program written 'stamp editor integrated development environment ide windows syntax checked tokenized sent chip serial/usb mini-b cable run currently four variants interpreter bs2 sub-variants feature memory higher execution speed additional specialized pbasic commands extra i/o pins etc. comparison original bs2 model bs1 bs2 use pic remaining basic stamp 2 variants use parallax sx processor third variant javelin stamp module uses subset sun microsystems java programming language instead parallax pbasic include networking facilities fourth variant spin stamp module based parallax propeller therefore uses spin programming language instead pbasic number companies make clones basic stamp additional features faster execution analog-to-digital converters hardware-based pwm run background parallax propeller gradually accumulating software libraries give functionality similar basic stamp however uniform list pbasic facilities spin equivalents
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Programming language topics
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megaphone desktop tool megaphone desktop tool windows action alert tool developed give israel united support giyus distributed world union jewish students world jewish congress jewish agency israel world zionist organization standwithus hasbara fellowships honestreporting pro-israel public relations organizations tool released july 2006 lebanon war june 2011 tool longer available giyus website rss newsfeed available megaphone desktop tool acted wrapper around rss feed giyus website originally gave user option going particular site poll user chooses go site software casts vote automatically technically feasible feature discontinued giyus tries save time effort locating voting form inside website seemingly simple task may prove quite confusing certain sites whenever technically direct straight voting action arrived poll results means directed straight voting action already successfully voted reason n't care vote always use thanks link article alert popup later versions voting concept removed entirely tool directed users anti-israel websites giving users option click button labeled act would direct user poll email address software license provides remote updates understand agree giyus.org may provide updates patches and/or new versions software time time including automatic updates installed computer notice needed continue use services hereby authorize installations according jerusalem post amir gissin head public affairs department foreign ministry israel expressed support tool use foreign ministry pushing idea urging supporters israel everywhere become cyberspace soldiers new battleground israel image reports computing website register described use software highly organised mass manipulation technologies supposed democratising claimed megaphone effectively high-tech exercise ballot-stuffing register also reported bbc history magazine website noticed upsurge voting whether holocaust denial criminal offence britain closing date already passed result already published votes invalid anyway stewart purvis former editor-in-chief itn noted independent panel reviewing bbc israeli-palestinian coverage received large number letters north america accused bbc anti-israeli states evidence pressure group involvement following success megaphone tool developers formed company collactive 2007 collactive released web assistant general-purpose commercial version megaphone tool tool received wide range reactions praise criticism amir gissin head public affairs department israeli foreign ministry praised tool noting efficacy adnan hajj photographs controversy obtaining admission reuters news agency photograph adnan hajj improperly edited photo editing software tool similarly praised number pro-israel organizations helping fight perceive anti-israel media bias time criticized independent television news others stuffing ballot online polls generating excessive comments 'spam internet message boards stifling online discussion seen mass participatory form propaganda june 2011 megaphone desktop tool unavailable download creators website currently alerts displayed giyus website rss feed
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Internet protocols
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malware research notion self-reproducing computer program traced back initial theories operation complex automata john von neumann showed theory program could reproduce constituted plausibility result computability theory fred cohen experimented computer viruses confirmed neumann postulate investigated properties malware detectability self-obfuscation using rudimentary encryption 1988 doctoral dissertation subject computer viruses cohen faculty advisor leonard adleman presented rigorous proof general case algorithmic determination presence virus undecidable problem must mistaken determination within broad class programs virus present problem differs require ability recognize viruses adleman proof perhaps deepest result malware computability theory date relies cantor diagonal argument well halting problem ironically later shown young yung adleman work cryptography ideal constructing virus highly resistant reverse-engineering presenting notion cryptovirus cryptovirus virus contains uses public key randomly generated symmetric cipher initialization vector iv session key sk cryptoviral extortion attack virus hybrid encrypts plaintext data victim machine using randomly generated iv sk iv+sk encrypted using virus writer public key theory victim must negotiate virus writer get iv+sk back order decrypt ciphertext assuming backups analysis virus reveals public key iv sk needed decryption private key needed recover iv sk result first show computational complexity theory used devise malware robust reverse-engineering growing area computer virus research mathematically model infection behavior worms using models lotka–volterra equations applied study biological virus various virus propagation scenarios studied researchers propagation computer virus fighting virus virus like predator codes effectiveness patching etc behavioral malware detection researched recently approaches behavioral detection based analysis system call dependencies executed binary code traced using strace precise taint analysis compute data-flow dependencies among system calls result directed graph formula_1 nodes system calls edges represent dependencies example formula_2 result returned system call formula_3 either directly result indirectly output parameters later used parameter system call formula_4 origins idea use system calls analyze software found work forrest et al christodorescu et al point malware authors easily reorder system calls without changing semantics program makes system call dependency graphs suitable malware detection compute difference malware goodware system call dependency graphs use resulting graphs detection achieving high detection rates kolbitsch et al pre-compute symbolic expressions evaluate syscall parameters observed runtime detect dependencies observing whether result obtained evaluation matches parameter values observed runtime malware detected comparing dependency graphs training test sets fredrikson et al describe approach uncovers distinguishing features malware system call dependency graphs extract significant behaviors using concept analysis leap mining babic et al recently proposed novel approach malware detection classification based grammar inference tree automata approach infers automaton dependency graphs show automaton could used detection classification malware research combining static dynamic malware analysis techniques also currently conducted effort minimize shortcomings studies researchers islam et al working integrate static dynamic techniques order better analyze classify malware malware variants
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Computer security
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cyber risk quantification cyber risk quantification involves application risk quantification techniques organization cybersecurity risk cyber risk quantification process evaluating cyber risks identified validating measuring analyzing available cyber data using mathematical modeling techniques accurately represent organization cybersecurity environment manner used make informed cybersecurity infrastructure investment risk transfer decisions cyber risk quantification supporting activity cybersecurity risk management cybersecurity risk management component enterprise risk management especially important organizations enterprises highly dependent upon information technology networks systems business operations one method quantifying cyber risk value-at-risk var method discussed january 2015 world economic forum meeting see external reference meeting var studied researched deemed viable method quantifying cyber risk metric related cyber risk quantification identified cited cyber risk reduction return investment cr3oi metric uses cyber var expression return investment single series cyber investments see cyber risk reduction return investment cyber risk quantification automated software supported process lets user create model system architecture uses built mathematical modeling techniques software quantify cyber security risks
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Computer security
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xsl attack cryptography extended sparse linearization xsl attack method cryptanalysis block ciphers attack first published 2002 researchers nicolas courtois josef pieprzyk caused controversy claimed potential break advanced encryption standard aes cipher also known rijndael faster exhaustive search since aes already widely used commerce government transmission secret information finding technique shorten amount time takes retrieve secret message without key could wide implications method high work-factor unless lessened means technique reduce effort break aes comparison exhaustive search therefore affect real-world security block ciphers near future nonetheless attack caused experts express greater unease algebraic simplicity current aes overview xsl attack relies first analyzing internals cipher deriving system quadratic simultaneous equations systems equations typically large example 8,000 equations 1,600 variables 128-bit aes several methods solving systems known xsl attack specialized algorithm termed extended sparse linearization applied solve equations recover key attack notable requiring handful known plaintexts perform previous methods cryptanalysis linear differential cryptanalysis often require unrealistically large numbers known chosen plaintexts solving multivariate quadratic equations mq finite set numbers np-hard problem general case several applications cryptography xsl attack requires efficient algorithm tackling mq 1999 kipnis shamir showed particular public key algorithm known hidden field equations scheme hfe could reduced overdetermined system quadratic equations equations unknowns one technique solving systems linearization involves replacing quadratic term independent variable solving resultant linear system using algorithm gaussian elimination succeed linearization requires enough linearly independent equations approximately many number terms however cryptanalysis hfe equations kipnis shamir proposed re-linearization technique extra non-linear equations added linearization resultant system solved second application linearization re-linearization proved general enough applicable schemes 2000 courtois et al proposed improved algorithm mq known xl extended linearization increases number equations multiplying monomials certain degree complexity estimates showed xl attack would work equations derived block ciphers aes however systems equations produced special structure xsl algorithm developed refinement xl could take advantage structure xsl equations multiplied carefully selected monomials several variants proposed research efficiency xl derivative algorithms remains ongoing yang chen 2004 courtois pieprzyk 2002 observed aes rijndael partially also serpent could expressed system quadratic equations variables represent plaintext ciphertext key bits also various intermediate values within algorithm s-box aes appears especially vulnerable type analysis based algebraically simple inverse function subsequently ciphers studied see systems equations produced biryukov de cannière 2003 including camellia khazad misty1 kasumi unlike forms cryptanalysis differential linear cryptanalysis one two known plaintexts required xsl algorithm tailored solve type equation systems produced courtois pieprzyk estimate optimistic evaluation shows xsl attack might able break rijndael 256 bits serpent key lengths 192 256 bits analysis however universally accepted example aes 4 conference bonn 2004 one inventors rijndael vincent rijmen commented xsl attack attack dream promptly courtois answered xsl may dream may also bad dream turn nightmare however neither later paper actions nsa nist give support remark courtois 2003 murphy robshaw discovered alternative description aes embedding larger cipher called bes described using simple operations single field gf 2 xsl attack mounted system yields simpler set equations would break aes complexity around 2 courtois pieprzyk analysis correct 2005 cid leurent gave evidence proposed form xsl algorithm provide efficient method solving aes system equations however courtois disputed findings fse 2007 chu-wee lim khoongming khoo showed possibly work presented even xsl works modern algorithms attack currently poses little danger terms practical security like many modern cryptanalytic results would so-called certificational weakness faster brute force attack resources required still huge unlikely real-world systems could compromised using future improvements could increase practicality attack however type attack new unexpected cryptographers expressed unease algebraic simplicity ciphers like rijndael bruce schneier niels ferguson write one criticism aes n't quite trust security… concerns us aes simple algebraic structure… block cipher know simple algebraic representation idea whether leads attack knowing reason enough skeptical use aes practical cryptography 2003 pp 56–57
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Computer security
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voice phishing voice phishing form criminal phone fraud using social engineering telephone system gain access private personal financial information purpose financial reward sometimes referred vishing portmanteau voice phishing landline telephone services traditionally trustworthy terminated physical locations known telephone company associated bill-payer however vishing fraudsters often use modern voice ip voip features caller id spoofing automated systems ivr make difficult legal authorities monitor trace block voice phishing typically used steal credit card numbers information used identity theft schemes individuals although use automated responders war dialers preferred vishers reported cases human operators play active role scams attempt persuade victims posing employee legitimate body bank police telephone internet provider fraudster attempts obtain personal details financial information regarding credit card bank accounts e.g pin well personal information victim received information fraudster might able access empty account commit identity fraud fraudsters may also try persuade victim transfer money another bank account withdraw cash given directly another simple trick used fraudsters ask called parties hang dial bank victim hangs fraudster keeping line open remaining connected victim picks phone dial doubt calling company telephone number listed billing statements official sources recommended opposed calling numbers received messages callers dubious authenticity however sometimes hanging redialing insufficient caller hung victim might still connected fraudster spoofs dial tone phone line entice victim dial fraudster accomplice answers impersonates whomever victim trying call known 'no hang-up scam hence consumers advised use different phone dialing company number confirm bank account data sensitive information targeted fraudsters also trying obtain security credentials consumers use microsoft apple products spoofing caller id microsoft apple inc.. sweden mobile bank id phone app launched 2011 used identify user internet banking user logs bank computer bank activates phone app user enters password phone logged fraudulent people called people claimed bank officer saying security problem asked use mobile bank id app victim say password logged fraudster computer second mobile bank id app log approved transfer money nordea even approved fraudster phone able approve usage victim account 2018 app changed must photograph qr code computer screen making sure phone computer physically located room mostly eliminated type fraud
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Computer security
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alexandre julliard alexandre julliard born 1970 computer programmer best known project leader wine compatibility layer run microsoft windows programs unix-like operating systems julliard studied computer science swiss federal institute technology lausanne spent 1990s working embedded systems works full-time wine codeweavers julliard enjoys astronomy currently lives lausanne switzerland
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Operating systems
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vital product data vital product data vpd collection configuration informational data associated particular set hardware software vpd stores information part numbers serial numbers engineering change levels devices attached system provide vpd often available pci scsi devices parallel ata usb devices also provide similar data refer vpd vpd data typically burned onto eeproms associated various hardware components queried attached i2c buses used firmware example openfirmware determine nature system hardware shield operation firmware minor changes variations hardware implementations within given machine model number ibm aix operating system vpd also refers subset database tables object data manager odm obtained either customized vpd object class platform specific areas therefore vpd odm terms sometimes referred interchangeably lscfg command used aix get vpd codice_1 linux commands codice_2 codice_3 codice_4 display hardware vital product data
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Operating systems
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nos/ve nos/ve network operating system virtual environment discontinued operating system time-sharing capabilities written control data corporation 1980s virtual memory operating system employing 64-bit virtual mode cdc cyber 180 series computers nos/ve replaced earlier nos nos/be operating systems 1970s command shell interface nos/ve called system command language scl short order callable scl command programs must declare parameters permits automatic usage summaries passing parameters name position type checking parameter values standard nos/ve commands follow particular naming convention form command verb adjective noun commands could abbreviated first three characters verb followed first character words examples inspired addressing structure-members various programming languages catalog separator dot subsystems like ftp integrate command shell change prompt add commands like get_file thereby statements like flow-control stay subsystems mixed procedures scripts commands could take parameters create_connection command would connect ip address 10.1.2.3 telnet service
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Operating systems
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reset vector reset vector default location central processing unit go find first instruction execute reset reset vector pointer address cpu always begin soon able execute instructions address section non-volatile memory initialized contain instructions start operation cpu first step process booting system containing cpu
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Computer architecture
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microsoft bookings microsoft bookings scheduling tool part microsoft office family products generally released microsoft march 2017 bookings allows customers small businesses companies book appointments company application available business premium subscribers office 365 july 20 2016 microsoft launched bookings customers u.s. canada office 365 business premium license march 20 2017 microsoft globally released bookings worldwide including launching bookings android ios
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Distributed computing architecture
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common criteria testing laboratory common criteria model provides separation roles evaluator certifier product certificates awarded national schemes basis evaluations carried independent testing laboratories common criteria testing laboratory third-party commercial security testing facility accredited conduct security evaluations conformance common criteria international standard facility must accredited according iso/iec 17025 national certification body list laboratory designations country common criteria recognition arrangement ccra common criteria mutual recognition arrangement mra limitations agreement past evaluations eal4+ recognized on-going transition away eal levels introduction ndpp evaluations “ map ” eal4 assurance components continue recognized united states national institute standards technology nist national voluntary laboratory accreditation program nvlap accredits cctls meet national information assurance partnership niap common criteria evaluation validation scheme requirements conduct security evaluations conformance common criteria laboratories must meet following requirements cctls enter contractual agreements sponsors conduct security evaluations products protection profiles use ccevs niap approved test methods derived common criteria common methodology technology based sources cctls must observe highest standards impartiality integrity commercial confidentiality cctls must operate within guidelines established ccevs become cctl testing laboratory must go series steps involve niap validation body nvlap nvlap accreditation primary requirement achieving cctl status scheme requirements satisfied nvlap accreditation addressed niap validation body present three scheme-specific requirements imposed validation body niap approved cctls must agree following testing laboratory becomes cctl laboratory approved niap validation body listed approved laboratories list avoid unnecessary expense delay becoming niap-approved testing laboratory strongly recommended prospective cctls ensure able satisfy scheme-specific requirements prior seeking accreditation nvlap accomplished sending letter intent niap prior entering nvlap process additional laboratory-related information found ccevs publications canada communications security establishment canada csec canadian common criteria scheme cccs oversees common criteria evaluation facilities ccef accreditation performed standards council canada scc program accreditation laboratories – canada palcan according can-p-1591 scc ’ adaptation iso/iec 17025-2005 itset laboratories approval performed ccs certification body body within csec verification applicant ability perform competent common criteria evaluations
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Computer security
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shannen rossmiller shannen rossmiller born may 31 1969 american lecturer instructor cyber counter-intelligence forensics former montana municipal court judge controversial role vigilante online terrorist-hunter part 7seas group former high school cheerleader paralegal mother three rossmiller posed online militant anti-american muslim radicals attract eye similar mindsets still member 7-seas group provided evidence led arrest conviction ryan g. anderson national guardsman deploy u.s. iraq ryan serving life sentence seeking aid enemy time war attempted espionage 2005 posing online al qaeda financier rossmiller offered transient michael reynolds 40,000 purchase fuel trucks attack american pipelines reynolds arrested attempted pick money 2007 convicted jury attempting provide material support al qaeda related charges sentenced 30 years jail rossmiller appeared 2005 bbc documentary entitled new al-qaeda along internet cyber sleuths criticized work july 2007 publicist seeking book movie deal based rossmiller story 2011 published book entitled unexpected patriot
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Computer security
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qualys qualys inc. provides cloud security compliance related services based foster city california founded 1999 qualys first company deliver vulnerability management solutions applications web using software service saas model 2013 gartner group fifth time gave qualys strong positive rating services added cloud-based compliance web application security offerings qualys 10,300 customers 130 countries including majority forbes global 100 company strategic partnerships major managed services providers consulting organizations including bt dell secureworks fujitsu ibm ntt symantec verizon wipro company also founding member cloud security alliance csa qualys founded 1999 company launched qualysguard december 2000 making qualys one first entrants vulnerability management market march 2001 angel investor philippe courtot became ceo company major investment company also serves chairman board qualysguard intranet scanner released 2002 automatically scan corporate lans vulnerabilities search available patch following year qualys released freemap web-based tool scanning mapping identifying possible security holes within networks connected internet 2005 qualys extended qualysguard product line 2008 qualys introduced qualysguard policy compliance extended platform ’ global scanning capabilities collect compliance data across organization map information policies document compliance auditing purposes qualys also released service web application scanning named qualysguard web application scanning 2010 rsa conference usa qualys announced qualysguard malware detection service new service designed scan identify malware web sites also announced qualys secure seal allows websites show visitors passed security scans july 2010 qualys announced qualys browsercheck service checking web browsers plug-ins security vulnerabilities rsa conference 2011 qualys launched new open source web application firewall project ironbee led ivan ristic creator modsecurity director engineering qualys rsa conference 2012 qualys introduced updates qualysguard cloud platform extended capabilities help customers improve security systems applications automate compliance initiatives it-grc provide online protection cyber-attacks reducing operational costs increasing efficiency security programs qualys went public nasdaq symbol qlys september 28 2012 raising net proceeds 87.5 million 2014 rsa conference qualys announced general availability qualyguard web application firewall waf provides protection websites running amazon ec2 on-premises well new continuous monitoring solution free top 4 security controls service 2015 company released 2.0 waf software included virtual patching customizable event responses year qualys also released security compliance solution called cloud agent platform august 2015 company released free asset management service qualys assetview allowed organizations keep inventory computers software february 2016 qualys released threatprotect vulnerability detection service cloud-based platform company received full certification configuration management databases cmdbs app servicenow allowing app integrated servicenow system march 2016 july 2016 announced qualys would integrate microsoft azure security center august 2017 qualys acquired network analysis assets nevis networks undisclosed sum december 2017 qualys announced acquisition netwatcher network security company april 2018 qualys acquired software assets singapore-based 1mobility startup develops security technologies mobile phones june 2018 qualys announced addition asset inventory cloud platform sc magazine awarded qualys security software solutions every year 2004-2014 sc magazine also awarded qualys best security company 2014 2010 inc. magazine ranked qualys within 5000 fastest growing private companies usa based 104 revenue growth 2006 2009 2012 silicon valley/san jose business journal recognized qualys one largest private companies silicon valley – ranking 26th list 51 november 2014 qualys received 2014 security reader choice awards best risk policy compliance solution best application security product best vulnerability 2014 2015 qualys received award best application security product sans institute 2017 frost sullivan recognizes qualys 2017 global vulnerability management market leadership award qualys honored cyber defense magazine 2017 cyber security leader
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Computer security
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filecoin filecoin ⨎ open-source public cryptocurrency digital payment system intended blockchain-based cooperative digital storage data retrieval method made protocol labs builds top interplanetary file system allowing users rent unused hard drive space
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Distributed computing architecture
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microsoft language portal microsoft language portal multilingual online dictionary computing terms also offers free downloads localization style guides translations user interface text feedback feature made public 2009
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Computational linguistics
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richfaces richfaces open source ajax-enabled component library javaserver faces hosted jboss allows easy integration ajax capabilities enterprise application development reached end-of-life june 2016 richfaces component library javaserver faces adds richfaces originated ajax4jsf framework alexander smirnov designed implemented autumn 2005 smirnov joined exadel continued develop framework march 2006 exadel released first version would become ajax4jsf later year exadel vcp split ajax4jsf framework richfaces born richfaces provided out-of-the-box components component-centric ajax approach components everything need ajax4jsf provided page-wide ajax support developers specify parts page server process client-side user actions parts updated processing ajax4jsf became open-source project hosted java.net richfaces became commercial jsf component library march 2007 jboss division red hat 2006 exadel signed partnership agreement whereby ajax4jsf richfaces would come jboss umbrella jboss ajax4jsf jboss richfaces richfaces would also become open-source free september 2007 jboss exadel decided merge ajax4jsf richfaces richfaces name made sense libraries free open-source one product solved many existing version- compatibility-issues version ajax4jsf would work version richfaces february 12th 2016 richfaces developer michal petrov announced end-of-life richfaces june 2016 framework implemented component library adds ajax capability existing pages developer ’ need write javascript code replace existing components new ajax widgets richfaces enables page-wide ajax support instead traditional component-wide support hence developer define event page invokes ajax request areas page synchronized jsf component tree ajax request changes data server according events fired client richfaces allows define means jsf tags different parts jsf page wish update ajax request provides options send ajax requests server also jsf page n't change regular jsf page n't need write javascript code hand controlling everything server side almost javascript needed page state maintained easily server architecture richfaces consists ajax filter ajax action components ajax containers javascript engine skinnability special feature richfaces used defining common interface styles feature based xcss technology provides flexibility dynamics richfaces provides set predefined skins skin properties generalbackgroundcolor generallinkcolor headerfamilyfont etc stored skinname.skin.properties file component xcss special file format combines flexibility xml css file performs mapping css selectors skin properties particular skin additionally richfaces provides skinning standard html controls create custom skin using plug-n-skin feature maven archetype builds skeleton new skin result presented code
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Programming language topics
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opensta opensta feature-rich gui-based web server benchmarking utility perform scripted http https heavy load tests performance measurements freely available distributable open source gnu general public license opensta currently runs microsoft windows-based operating systems scripts recorded proprietary language called scl fairly simple coding language provides support custom functions variable scopes random sequential lists opensta originally written cyrano cyrano intentions write commercial plug modules support opensta performance testing non-web applications note recent version posted opensta home page 1.4.4 released 27 oct 2007
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Internet protocols
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katie moussouris katie moussouris american computer security researcher entrepreneur pioneer vulnerability disclosure best known ongoing work advocating responsible security research previously member stake created bug bounty program microsoft directly involved creating u.s. department defense first bug bounty program hackers previously served chief policy officer hackerone vulnerability disclosure company based san francisco california currently founder ceo luta security moussouris interested computers young age learned program basic commodore 64 mother bought 3rd grade first girl take ap computer science high school attended simmons college study molecular biology mathematics simultaneously worked human genome project mit whitehead institute whitehead transitioned lab assistant systems administrator role three years became systems administrator mit department aeronautics astronautics helped design computer system new lab open 2000 time also worked systems administrator harvard school engineering applied sciences moved california work linux developer turbolinux started computer security response program active within west coast hacker scene formally joined stake penetration tester 2002 invitation chris wysopal moussouris joined symantec october 2004 acquired stake founded managed symantec vulnerability research 2004 first program allow symantec researchers publish vulnerability research may 2007 moussouris left symantec join microsoft security strategist founded microsoft vulnerability research msvr program announced blackhat 2008 program coordinated response several significant vulnerabilities including dan kaminsky dns flaw also actively looked bugs third-party software affecting microsoft customers subsequent examples include google project zero september 2010 may 2014 moussouris senior security strategist lead microsoft ran security community outreach strategy team microsoft part microsoft security response center msrc team instigated microsoft bluehat prize advancement exploit mitigations awarded 260,000 prizes researchers blackhat usa 2012 grand prize 200,000 time largest cash payout offered software vendor also created microsoft first bug bounty program paid 253,000 received 18 vulnerabilities course tenure moussouris helped edit iso/iec 29147 document since around 2008 april 2016 iso made standard freely available charge request moussouris cert coordination center art manion may 2014 moussouris named chief policy officer hackerone vulnerability disclosure company based san francisco california role moussouris responsible company vulnerability disclosure philosophy worked promote legitimize security research among organizations legislators policy makers still microsoft moussouris began discussing bug bounty program federal government continued talks moved hackerone march 2016 moussouris directly involved creating department defense hack pentagon pilot program organized vetted hackerone first bug bounty program history us federal government moussouris followed pentagon program hack air force hackerone luta security partnering deliver 20 bug bounty challenges three years defense department april 2016 moussouris founded luta security consultancy help organizations governments work collaboratively hackers bug bounty programs 2015-2016 2016-2017 katie moussouris served cybersecurity fellow new america u.s. based think tank 2013 wassenaar arrangement export controls conventional arms dual-use goods technologies amended include intrusion software moussouris wrote op-ed wired criticizing move harmful vulnerability disclosure industry due overly-broad definition encouraged security experts write help regulators understand make right changes invited technical expert directly assist us wassenaar arrangement negotiations helped rewrite amendment adopt end-use decontrol exemptions based intent user moussouris visiting scholar mit sloan school management affiliate researcher harvard belfer center science international affairs conducted economic research labor market security bugs coauthored book chapter first system dynamics model vulnerability economy exploit market published mit press 2017 2018 moussouris testified front u.s. senate subcommittee consumer protection product safety insurance data security security research defensive purposes 2014 sc magazine named moussouris women security list also named one 10 women information security everyone know one watch among 2011 women influence awards 2018 featured among america top 50 women tech forbes september 2015 moussouris filed discrimination class-action lawsuit microsoft federal court seattle alleged microsoft hiring practices upheld practice sex discrimination women technical engineering roles respect performance evaluations pay promotions terms conditions employment
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Computer security
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apache nutch apache nutch highly extensible scalable open source web crawler software project nutch coded entirely java programming language data written language-independent formats highly modular architecture allowing developers create plug-ins media-type parsing data retrieval querying clustering fetcher robot web crawler written scratch specifically project nutch originated doug cutting creator lucene hadoop mike cafarella june 2003 successful 100-million-page demonstration system developed meet multi-machine processing needs crawl index tasks nutch project also implemented mapreduce facility distributed file system two facilities spun subproject called hadoop january 2005 nutch joined apache incubator graduated become subproject lucene june year since april 2010 nutch considered independent top level project apache software foundation february 2014 common crawl project adopted nutch open large-scale web crawl goal nutch project release global large-scale web search engine longer case nutch following advantages simple fetcher ibm research studied performance nutch/lucene part commercial scale cso project findings scale-out system nutch/lucene could achieve performance level cluster blades achievable scale-up computer power5 clueweb09 dataset used e.g trec gathered using nutch average speed 755.31 documents per second
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Web technology
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internet crime complaint center mission internet crime complaint center also known ic3 provide public reliable convenient reporting mechanism submit information federal bureau investigation fbi concerning suspected internet-facilitated criminal activity develop alliances law enforcement industry partners information analyzed disseminated investigative intelligence purposes law enforcement public awareness since 2000 ic3 received complaints crossing spectrum cyber crime matters include online fraud many forms including intellectual property rights ipr matters computer intrusions hacking economic espionage theft trade secrets online extortion international money laundering identity theft growing list internet facilitated crimes become increasingly evident regardless label placed cyber crime matter potential overlap another referred matter substantial therefore ic3 formerly known internet fraud complaint center ifcc renamed october 2003 better reflect broad character matters internet cyber nexus referred ic3 minimize need one distinguish internet fraud potentially overlapping cyber crimes ic3 purpose serve central hub receive develop refer criminal complaints regarding rapidly expanding occurrences internet crime ic3 gives victims convenient easy-to-use reporting mechanism alerts authorities suspected criminal civil violations internet ic3 develops leads notifies law enforcement agencies federal state local international level
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Computer security
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x86 instruction listings x86 instruction set refers set instructions x86-compatible microprocessors support instructions usually part executable program often stored computer file executed processor x86 instruction set extended several times introducing wider registers datatypes well new functionality full 8086/8088 instruction set intel instructions available 32-bit mode operate 32-bit registers eax ebx etc values instead 16-bit ax bx etc counterparts see also x86 assembly language quick tutorial processor family updated instruction set also grouped according architecture i386 i486 i686 generally referred x86 32 x86 64 also known amd64 also mmx registers mmx support instructions added usable integer floating point operations see amd changed cpuid detection bit feature k6-ii lzcnt popcnt population count advanced bit manipulation andn bextr blsi blsmsk blsr tzcnt bzhi mulx pdep pext rorx sarx shrx shlx bextr blcfill blci blcic blcmask blcs blsfill blsic t1mskc tzmsk fxrstor fxsave also supported later pentium iis contain sse support fisttp x87 integer conversion truncation regardless status word mmx instructions operate mm registers 64 bits wide shared fpu registers added pentium mmx added 6x86mx cyrix deprecated paveb paddsiw pmagw pdistib psubsiw pmvzb pmulhrw pmvnzb pmvlzb pmvgezb pmulhriw pmachriw following mmx instruction added sse also available athlon name mmx+ following mmx instructions added sse2 added k6-2 femms pavgusb pf2id pfacc pfadd pfcmpeq pfcmpge pfcmpgt pfmax pfmin pfmul pfrcp pfrcpit1 pfrcpit2 pfrsqit1 pfrsqrt pfsub pfsubr pi2fd pmulhrw prefetch prefetchw pf2iw pfnacc pfpnacc pi2fw pswapd pfrsqrtv pfrcpv added pentium iii sse instructions operate xmm registers 128 bit wide sse consists following sse simd floating-point instructions added pentium 4 sse2 allows execution mmx instructions sse registers processing twice amount data following instructions used sse registers since nature work mmx registers added pentium 4 supporting sse3 added xeon 5100 series initial core 2 following mmx-like instructions extended sse registers added ssse3 added core 2 manufactured 45nm added phenom processors added nehalem processors sse5 proposed sse extension amd bundle include full set intel sse4 instructions making competitor sse4 rather successor amd chose implement sse5 originally proposed however derived sse extensions introduced introduced bulldozer processor core removed zen microarchitecture onward revision sse5 instruction set half-precision floating-point conversion supported amd processors starting piledriver architecture intel starting haswell processors broadwell processors since 2014 fused multiply-add floating-point vector multiply–accumulate three operands supported amd processors starting bulldozer architecture supported intel chip 2017 fused multiply-add four operands fma4 realized hardware fma3 avx first supported intel sandy bridge amd bulldozer vector operations 256 bit registers introduced intel haswell microarchitecture amd excavator expansion vector integer sse avx instructions 256 bits introduced intel xeon phi x200 vector operations 512 bit registers 6 new instructions 7 new instructions x86 cpus contain undocumented instructions implemented chips listed official documents found various sources across internet ralf brown interrupt list sandpile.org ffreep performs ffree st pop stack
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Computer architecture
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havok software havok middleware software suite developed irish company havok havok provides physics engine component related functions video games september 14 2007 intel announced signed definitive agreement acquire havok inc 2008 havok honored 59th annual technology engineering emmy awards advancing development physics engines electronic entertainment october 2 2015 microsoft announced acquired havok havok middleware suite consists following modules version 1.0 havok sdk unveiled game developers conference gdc 2000 havok sdk multi-platform nature always updated run majority latest platforms licensees given access c/c++ source-code giving freedom customize engine features port different platforms although libraries provided binary format march 2011 havok showed version havok physics engine designed use sony xperia play specifically android 2.3 microsoft //build/ 2012 conference havok unveiled full technology suite windows 8 windows rt windows phone 8 later windows 10 since sdk launch 2000 used 600 video games havok also found havok supplies tools havok content tools export assets use havok products autodesk 3ds max autodesk maya autodesk softimage havok also used virtual world second life physics handled online simulator servers rather users client computers upgrade havok version 4 released april 2008 upgrade version 7 started june 2010 second life resident emilin nakamori constructed weight-driven pendulum-regulated mechanical clock functioning entirely havok physics march 2019
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Distributed computing architecture
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simulink simulink developed mathworks graphical programming environment modeling simulating analyzing multidomain dynamical systems primary interface graphical block diagramming tool customizable set block libraries offers tight integration rest matlab environment either drive matlab scripted simulink widely used automatic control digital signal processing multidomain simulation model-based design mathworks third-party hardware software products used simulink example stateflow extends simulink design environment developing state machines flow charts mathworks claims coupled another products simulink automatically generate c source code real-time implementation systems efficiency flexibility code improves becoming widely adopted production systems addition tool embedded system design work flexibility capacity quick iteration embedded coder creates code efficient enough use embedded systems simulink real-time formerly known xpc target together x86-based real-time systems environment simulating testing simulink stateflow models real-time physical system another mathworks product also supports specific embedded targets used generic products simulink stateflow automatically generate synthesizable vhdl verilog simulink verification validation enables systematic verification validation models modeling style checking requirements traceability model coverage analysis simulink design verifier uses formal methods identify design errors like integer overflow division zero dead logic generates test case scenarios model checking within simulink environment simevents used add library graphical building blocks modeling queuing systems simulink environment add event-based simulation engine time-based simulation engine simulink therefore simulink type simulation done model simulated point environment different type blocks accessed using simulink library browser therefore benefit could taken environment efficiently
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Programming language topics
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security breach notification laws security breach notification laws data breach notification laws laws require entity subject data breach notify customers parties breach take steps remediate injuries caused breach laws irregularly enacted 50 u.s. states since 2002 last 3 states privacy laws protecting citizens late 2016 new mexico passed privacy law 2017 south dakota alabama 2018 laws enacted response escalating number breaches consumer databases containing personally identifiable information first law california data security breach notification law enacted 2002 became effective july 1 2003 related bill statement law requires state agency person business conducts business california owns licenses computerized data includes personal information defined disclose specified ways breach security data defined resident california whose unencrypted personal information reasonably believed acquired unauthorized person addition law permits delayed notification law enforcement agency determines would impede criminal investigation law also requires entity licenses information notify owner licensee information breach security data general state laws follow basic tenets california original law companies must immediately disclose data breach customers usually writing california since broadened law include compromised medical health insurance information bills differ level breach must reported state attorney general usually affects 500 1000 individuals states like california publish data breach notifications oag.gov websites breaches must reported sensitive personally identifying information acquired reasonably believed acquired unauthorized person reasonably likely cause substantial harm individuals information relates leaves room interpretation cause substantial harm breaches encrypted data need reported must reported data obtained viewed unauthorized individuals long reason believe use data harmful ways national conference state legislatures maintains list enacted proposed security breach notification laws number bills would establish national standard data security breach notification introduced u.s. congress none passed 109th congress 2015 state union speech president obama proposed new legislation create national data breach standard would establish 30-day notification requirement discovery breach european union implemented breach notification law directive privacy electronic communications e-privacy directive 2009 specific personal data held telecoms internet service providers directive implemented national law 25 may 2011 furthermore traffic data subscribers use voice data via network company saved company operational reasons however traffic data must deleted ’ necessary anymore order avoid breaches hand traffic data necessary creation treatment subscriber billing use data available end period bill repaid based law european union article 6 paragraphs 1-6 regarding marketing usage traffic data sale additional chargeable services used company subscriber gives his/her consent consent withdrawn every time also service provider must inform subscriber user types traffic data processed duration based assumptions processing traffic data accordance details must restricted persons acting authority providers public communications networks publicly available electronic communications services handling billing traffic management customer enquiries fraud detection marketing electronic communications services providing value added service must restricted necessary purposes activities
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Computer security
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intertec superbrain intertec superbrain all-in-one commercial microcomputer first sold intertec data systems corp. columbia south carolina usa 1979 machine ran operating system cp/m somewhat unusual used dual z80 cpus second used disk controller 1983 basic machine sold 2000 several variants including superbrain ii superbrain ii jr. qd quad density disk drives sd super density models superbrain notable user end first kermit connection 1981 machine practical useful office environment somewhat limited arrival first 5mb hard drive one floppy drive bays soon replaced 10mb hard drive effectively removed limitations could programmed stored
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Operating systems
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yaws web server yaws yet another web server web server written erlang claes klacke wikström yaws embedded erlang-based applications run regular standalone web server yaws uses erlang lightweight threading system performs well high concurrency load test conducted 2002 comparing yaws apache found hardware tested apache 2.0.39 worker mpm failed 4,000 concurrent connections yaws continued functioning 80,000 concurrent connections load test concludes problem apache related apache code per se due manner underlying operating system linux implements concurrency believe system implemented using operating system threads processes would exhibit similar performance erlang make use underlying os threads processes managing process pool thus suffer limitations .and underlined part formatting added expresses opinion founding technologies make difference scalability
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Web technology
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cobra command 1984 video game cobra command known japan interactive movie game originally released data east 1984 laserdisc-based coin-operated arcade game terrorists threatening free world amassed diabolical force brave pilot cobra command vanquish terrorist threat save free world total destruction player assumes role pilot lx-3 super cobra helicopter missions go across new york city streets statue liberty atlantic ocean italy grand canyon enemy headquarters easter island original arcade version interactive movie shooter game player watches scenes helicopter flies conflict zone game screen represented helicopter cockpit player controls crosshair moved aim enemy forces game features joystick two buttons one machine gun one missile game played 1 2 players certain moments voice pilot commanding officer helps player completing mission firing enemy forces dodging enemy fire natural surroundings pressing joystick directional pad correct direction right time pilot makes mistake anime sequence shows cobra helicopter blown player loses life lives lost game screen shows cobra smoldering ruins pilot presumably dead crash mega-cd port cobra command developed wolf team released 1992 cobra command later re-released japan playstation sega saturn 1995 two-in-one compilation road blaster another fmv game produced team data east released second game titled cobra command 1988 unlike 1984 version 1988 arcade game side-scrolling shoot-'em-up november 2009 revolutionary concepts developed published enhanced iphone os version laserdisc original yoshihisa kishimoto director cobra command also directed arcade versions double dragon battle chopper cobra command makes cameo inside garage billy jimmy walked opening sequence double dragon ii kunio-kun double dragon series creator yoshihisa kishimoto designed entirely new game cobra command using data east bega battle hardware therefore bega battle become somewhat rare even among laserdisc games cobra command developed data east co-operation external company toei animation first published japan 1984 thunder storm released later year north america cobra command one data east interactive movie games despite name similarities animation relation organization cobra command elements g.i joe franchise. also largely animated toei animation hence similarities animation style game cobra command hero pilot reviewing sega cd version wizard magazine glenn rubenstein praised high number levels unique interface gave game b- release famicom tsūshin scored sega saturn version game 25 40 giving playstation version 23 40
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Computer architecture
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relocation computing relocation process assigning load addresses position-dependent code data program adjusting code data reflect assigned addresses prior advent multiprocess systems still many embedded systems addresses objects absolute starting known location often zero since multiprocessing systems dynamically link switch programs became necessary able relocate objects using position-independent code linker usually performs relocation conjunction symbol resolution process searching files libraries replace symbolic references names libraries actual usable addresses memory running program relocation typically done linker link time also done load time relocating loader run time running program architectures avoid relocation entirely deferring address assignment run time known zero address arithmetic object files segmented various memory segment types example segments include code segment .text initialized data segment .data uninitialized data segment .bss others relocation table list pointers created translator compiler assembler stored object executable file entry table fixup pointer absolute address object code must changed loader relocates program refer correct location fixups designed support relocation program complete unit cases fixup table relative base address zero fixups must changed loader moves table architectures fixup crosses certain boundaries segment boundary aligned word boundary illegal flagged error linker far pointers 32-bit pointers segment offset used address 20-bit 640 kb memory space available dos programs point code data within dos executable exe absolute segments actual address code/data depends program loaded memory known program loaded instead segments relative values dos exe file segments need corrected executable loaded memory exe loader uses relocation table find segments need adjusted 32-bit windows operating systems mandatory provide relocation tables exe files since first image loaded virtual address space thus loaded preferred base address dlls exes opt address space layout randomization aslr exploit mitigation technique introduced windows vista relocation tables become mandatory possibility binary may dynamically moved executed even though still first thing loaded virtual address space running native 64-bit binaries windows vista aslr mandatory thus relocation sections omitted compiler executable linkable format elf executable format shared library format used unix-like systems allows several types relocation defined linker reads segment information relocation tables object files performs relocation following example uses donald knuth mix architecture mixal assembly language principles architecture though details change
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Programming language topics
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macaulay2 macaulay2 free computer algebra system developed daniel grayson university illinois urbana–champaign michael stillman cornell university computation commutative algebra algebraic geometry stillman along dave bayer authored predecessor macaulay software named francis sowerby macaulay english mathematician made significant contributions algebraic geometry macaulay2 uses high level programming language intended closely match syntax used mathematicians field published gnu general public license version 2 core macaulay2 implementation gröbner basis methods computing syzygies manipulating systems polynomial equations 2006 interview andrei okounkov cited macaulay2 along tex successful open-source project used mathematics suggested funding agencies look learn examples macaulay2 use emacs gnu texmacs
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Programming language topics
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stateflow stateflow developed mathworks control logic tool used model reactive systems via state machines flow charts within simulink model stateflow uses variant finite-state machine notation established david harel enabling representation hierarchy parallelism history within state chart stateflow also provides state transition tables truth tables stateflow generally used specify discrete controller model hybrid system continuous dynamics i.e. behavior plant environment specified using simulink specific applications stateflow include number mathworks third-party tools used stateflow validate design generate code example simulink verification validation mathworks tool used check requirements traceability model coverage analysis add-on code generation tools used automatically generate c c++ hdl plc code implementation embedded systems
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Programming language topics
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locky locky ransomware malware released 2016 delivered email allegedly invoice requiring payment attached microsoft word document contains malicious macros user opens document appears full garbage includes phrase enable macro data encoding incorrect social engineering technique user enable macros save run binary file downloads actual encryption trojan encrypt files match particular extensions filenames converted unique 16 letter number combination initially .locky file extension used encrypted files subsequently file extensions used including .zepto .odin .aesir .thor .zzzzz encryption message displayed user desktop instructs download tor browser visit specific criminal-operated web site information web site contain instructions demand payment 0.5 1 bitcoin november 2017 one bitcoin varies value 9,000 10,000 via bitcoin exchange since criminals possess private key remote servers controlled victims motivated pay decrypt files commonly reported mechanism infection involves receiving email microsoft word document attachment contains code document gibberish prompts user enable macros view document enabling macros opening document launch locky virus virus launched loads memory users system encrypts documents hash.locky files installs .bmp .txt files encrypt network files user access different route ransomware since uses macros attachments spread rather installed trojan using previous exploit june 22 2016 necurs released new version locky new loader component includes several detection-avoiding techniques detecting whether running within virtual machine within physical machine relocation instruction code since locky released numerous variants released used different extensions encrypted files many extensions named gods norse egyptian mythology first released extension used encrypted files .locky versions utilized .zepto .odin .shit .thor .aesir .zzzzz extensions encrypted files current version released december 2016 utilizes .osiris extension encrypted files many different distribution methods locky used since ransomware released distribution methods include exploit kits word excel attachments malicious macros docm attachments zipped js attachments general consensus among security experts protect ransomware including locky keep installed programs updated open attachments known senders locky uses rsa-2048 aes-128 cipher ecb mode encrypt files keys generated server side making manual decryption impossible locky ransomware encrypt files fixed drives removable drives network ram disk drives locky reported sent half-million users february 16 2016 period immediately attackers increased distribution millions users despite newer version google trend data indicates infections dropped around june 2016 february 18 2016 hollywood presbyterian medical center paid 17,000 ransom form bitcoins decryption key patient data hospital infected delivery email attachment disguised microsoft word invoice led increased fear knowledge ransomware general brought ransomware public spotlight appears trend ransomware used attack hospitals appears growing may 31 necurs went dormant perhaps due glitch c c server according softpedia less spam emails locky dridex attached june 22 however malwaretech discovered necurs bots consistently polled dga c c server replied digitally signed response signified necurs longer dormant cybercriminal group also started sending large quantity spam emails new improved versions locky dridex attached well new message zipped javascript code emails april 2016 dartford science technology college computers infected virus student opened infected email quickly spread encrypted many school files virus stayed computer several weeks eventually managed remove virus using system restore computers example message locky attachment following dear random name please find attached invoice services rendered additional disbursements above-mentioned matter hoping satisfaction remain sincerely random name random title
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Computer security
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warvox warvox free open-source voip-based war dialing tool exploring classifying auditing phone systems warvox processes audio call using signal processing techniques without need modems warvox uses voip providers internet instead modems used war dialers compares pauses words identify numbers using particular voicemail systems warvox merged metasploit project august 2011
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Computer security
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samuel j leffler samuel j leffler computer scientist known extensive work bsd 1980s freebsd present day among projects created flexfax libtiff freebsd wireless device drivers design implementation series books co-authored working computer systems research group csrg uc berkeley university california berkeley mr. leffler helped 4.1 4.2 bsd release contributed almost every aspect bsd systems including networking subsystem leaving computer systems research group mr. leffler also worked lucasfilm pixar animation studios silicon graphics alias research softimage creative environment cinetron computer systems vmware later became independent consultant system design
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Operating systems
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forward anonymity forward anonymity analogous forward secrecy computer security cryptography property prevents attacker recorded past communications discovering identities participants even fact speaking forward secrecy system designers attempt prevent attacker recorded past communications discovering contents said communications later one example system satisfies perfect forward secrecy property one compromise one key attacker consequent decryption messages encrypted key undermine security previously used keys forward secrecy refer protecting content message rather protection keys used decrypt messages one example system uses forward anonymity public key cryptography system public key well-known used encrypt message unknown private key used decrypt system one keys always said compromised messages participants still unknown anyone without corresponding private key originally introduced whitfield diffie paul van oorschot michael james wiener describe property sts station-to-station protocol involving long term secret either private key shared password public key cryptography common form forward anonymous system used pass encrypted messages preventing information message discovered message intercepted attacker uses two keys public key private key public key published used anyone encrypt plaintext message private key well known used decrypt cyphertext public key cryptography known asymmetric decryption algorithm different keys used perform opposing functions public key cryptography popular computationally easy create pair keys extremely difficult determine private key knowing public key therefore public key well known allow messages intercepted decrypted forward anonymous system one compromised key public key compromise anonymity system variation public key cryptography system web trust user public private key messages sent encrypted using intended recipient public key recipient private key decrypt message also signed senders private key creates added security becomes difficult attacker pretend user lack private key signature indicates non-trusted user forward anonymous system necessarily mean wholly secure system successful cryptanalysis message sequence messages still decode information without use private key long term secret forward anonymity along cryptography related properties received burst media attention leak classified information edward snowden beginning june 2013 indicated nsa fbi practices asking companies leave back doors allowing companies agencies decrypt information stored phones devices easily intention allowing easily find arrest various criminals occasionally mistakenly targeting innocent civilians especially publicized aid practice provided catching predatory pedophiles opponents practice argue leaving back door law enforcement increases risk attackers able decrypt information well questioning legality us constitution specifically form illegal search seizure
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Computer security
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zmeu vulnerability scanner zmeu computer vulnerability scanner searches web servers open attack phpmyadmin program apparently named zmeu dragon-like romanian folklore
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Computer security
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global surveillance global surveillance refers mass surveillance entire populations across national borders roots traced back middle 20th century ukusa agreement jointly enacted united kingdom united states later expanded canada australia new zealand create present five eyes alliance alliance developed cooperation arrangements several third-party nations eventually resulted establishment global surveillance network code-named echelon 1971 existence however widely acknowledged governments mainstream media global surveillance disclosures edward snowden triggered debate right privacy digital age origins global surveillance traced back late 1940s ukusa agreement collaboratively enacted united kingdom united states eventually culminated creation global surveillance network code-named echelon 1971 aftermath 1970s watergate affair subsequent congressional inquiry led sen. frank church revealed nsa collaboration britain gchq routinely intercepted international communications prominent anti-vietnam war leaders jane fonda dr. benjamin spock decades later multi-year investigation european parliament highlighted nsa role economic espionage report entitled 'development surveillance technology risk abuse economic information 1999 however general public series detailed disclosures internal nsa documents june 2013 first revealed massive extent nsa spying foreign domestic leaked ex-contractor edward snowden even number older global surveillance programs prism xkeyscore tempora referenced 2013 release thousands documents many countries around world including western allies member states nato targeted five eyes strategic alliance australia canada new zealand uk usa—five english-speaking western countries aiming achieve total information awareness mastering internet analytical tools boundless informant confirmed nsa director keith b. alexander 26 september 2013 nsa collects stores phone records american citizens much data kept large storage facilities utah data center us 1.5 billion megaproject referred wall street journal symbol spy agency surveillance prowess 6 june 2013 britain guardian newspaper began publishing series revelations yet unknown american whistleblower revealed several days later ex-cia ex-nsa-contracted systems analyst edward snowden snowden gave cache documents two journalists glenn greenwald laura poitras greenwald later estimated cache contains 15,000 – 20,000 documents large detailed small two subsequent months publications became clear nsa operated complex web spying programs allowed intercept internet telephone conversations billion users dozens countries around world specific revelations made china european union latin america iran pakistan australia new zealand however published documentation reveals many programs indiscriminately collected bulk information directly central servers internet backbones almost invariably carry reroute information distant countries due central server backbone monitoring many programs overlapped interrelated among one another programs often carried assistance us entities united states department justice fbi sanctioned us laws fisa amendments act necessary court orders signed secret foreign intelligence surveillance court nsa programs directly aided national foreign intelligence agencies britain gchq australia dsd well large private telecommunications internet corporations verizon telstra google facebook snowden disclosures nsa surveillance activities continuation news leaks ongoing since early 2000s one year september 11 2001 attacks former u.s. intelligence official william binney publicly critical nsa spying u.s. citizens disclosures followed 16 december 2005 new york times published report headline bush lets u.s. spy callers without courts 2006 evidence nsa domestic surveillance u.s. citizens provided usa today newspaper released report 11 may 2006 regarding nsa massive database phone records collected tens millions u.s. citizens according usa today phone records provided several telecom companies verizon bellsouth 2008 security analyst babak pasdar revealed existence so-called quantico circuit team discovered 2003 brought update carrier security system circuit provided u.s. federal government backdoor network unnamed wireless provider later independently identified verizon snowden made first contact journalist glenn greenwald guardian late 2012 timeline mass surveillance disclosures snowden continued throughout entire year 2013 documents leaked snowden 2013 include court orders memos policy documents related wide range surveillance activities according april 2013 summary documents leaked snowden combat terrorism surveillance programs employed assess foreign policy economic stability countries gather commercial secrets statement addressed national congress brazil early august 2013 journalist glenn greenwald maintained u.s. government used counter-terrorism pretext clandestine surveillance order compete countries business industrial economic fields december 2013 letter brazilian government snowden wrote programs never terrorism 're economic spying social control diplomatic manipulation 're power according white house panel member nsa n't stop terrorist attack however nsa chief said surveillance programs stopped 54 terrorist plots interview der spiegel published 12 august 2013 former nsa director michael hayden admitted nsa steal secrets 're number one hayden also added steal stuff make safe make rich according documents seen news agency reuters secrets subsequently funnelled authorities across nation help launch criminal investigations americans federal agents instructed recreate investigative trail order cover information originated according congressional testimony keith b. alexander director national security agency one purposes data collection store phone records inside place searched assessed times asked senator mark udall goal nsa collect phone records americans alexander replied yes believe nation best interest put phone records lockbox could search nation needs united states nsa collecting phone records 300 million americans international surveillance tool xkeyscore allows government analysts search vast databases containing emails online chats browsing histories millions individuals britain global surveillance program tempora intercepts fibre-optic cables form backbone internet nsa prism surveillance program data already reached final destination would directly harvested servers following u.s. service providers microsoft yahoo google facebook paltalk aol skype youtube apple inc nsa uses analysis phone call e-mail logs american citizens create sophisticated graphs social connections identify associates locations certain times travelling companions personal information according top secret nsa documents leaked snowden single day 2012 nsa collected e-mail address books day nsa collects contacts estimated 500,000 buddy lists live-chat services well inbox displays web-based e-mail accounts taken together data enables nsa draw detailed maps person life based personal professional religious political connections federal agencies united states data gathered surveillance programs routinely shared u.s. federal bureau investigation fbi u.s. central intelligence agency cia addition nsa supplies domestic intercepts drug enforcement administration dea internal revenue service irs law enforcement agencies foreign countries result nsa secret treaties foreign countries data gathered surveillance programs routinely shared countries signatories ukusa agreement foreign countries also help operate several nsa programs xkeyscore see international cooperation special branch nsa called follow money ftm monitors international payments banking credit card transactions later stores collected data nsa financial databank tracfin mobile phone tracking refers act attaining position coordinates mobile phone according washington post nsa tracking locations mobile phones world tapping cables connect mobile networks globally serve u.s. cellphones well foreign ones process nsa collects 5 billion records phone locations daily basis enables nsa analysts map cellphone owners relationships correlating patterns movement time thousands millions phone users cross paths order decode private conversations nsa cracked commonly used cellphone encryption technology a5/1 according classified document leaked snowden agency process encrypted a5/1 even acquired encryption key addition nsa uses various types cellphone infrastructure links carrier networks determine location cellphone user tracked visitor location registers worldwide sales smartphones grew rapidly nsa decided take advantage smartphone boom particularly advantageous smartphone contains variety data sets would interest intelligence agency social contacts user behaviour interests location photos credit card numbers passwords according documents leaked snowden nsa set task forces assigned several smartphone manufacturers operating systems including apple inc. iphone ios operating system well google android mobile operating system similarly britain gchq assigned team study crack blackberry addition smaller nsa programs known scripts perform surveillance 38 different features ios 3 ios 4 operating systems include mapping feature voicemail photos well google earth facebook yahoo messenger contrast prism surveillance program front-door method access nominally approved fisa court muscular surveillance program noted unusually aggressive usage unorthodox hacking methods infiltrate yahoo google data centres around world program operated overseas united kingdom nsa presumes anyone using foreign data link foreigner therefore able collect content metadata previously unknown scale u.s. citizens residents according documents leaked snowden muscular surveillance program jointly operated nsa britain gchq agency see international cooperation five eyes made repeated attempts spy internet users communicating secret via anonymity network tor several clandestine operations involve implantation malicious code computers anonymous tor users visit infected websites cases nsa gchq succeeded blocking access anonymous network diverting tor users insecure channels cases nsa gchq able uncover identity anonymous users royal concierge surveillance program britain gchq agency uses automated monitoring system infiltrate reservation systems least 350 luxury hotels many different parts world related surveillance programs involve wiretapping room telephones fax machines used targeted hotels well monitoring computers hooked hotel network u.s. national security agency nsa u.s. central intelligence agency cia britain government communications headquarters gchq conducting surveillance networks many online games including massively multiplayer online role-playing games mmorpgs world warcraft well virtual worlds second life xbox gaming console according april 2013 summary disclosures nsa defined intelligence priorities scale 1 highest interest 5 lowest interest classified 30 countries 3rd parties cooperates also spies prominent targets included members adherents internet group known anonymous well potential whistleblowers according snowden nsa targeted reporters wrote critically government 9/11 part joint operation central intelligence agency cia nsa deployed secret eavesdropping posts eighty u.s. embassies consulates worldwide headquarters nato also used nsa experts spy european union 2013 documents provided edward snowden revealed following intergovernmental organizations diplomatic missions government ministries subjected surveillance five eyes world war ii brusa agreement signed governments united states united kingdom purpose intelligence sharing later formalized ukusa agreement 1946 secret treaty full text agreement released public 25 june 2010 although treaty later revised include countries denmark germany ireland norway turkey philippines information sharing performed so-called five eyes term referring following english-speaking western democracies respective intelligence agencies left sea-me-we 3 runs across afro-eurasian supercontinent japan northern germany one important submarine cables accessed five eyes singapore former british colony asia-pacific region blue dot plays vital role intercepting internet telecommunications traffic heading australia/japan europe vice versa intelligence-sharing agreement singapore australia allows rest five eyes gain access sea-me-we 3 right tat-14 telecommunications cable linking europe united states identified one assets critical infrastructure key resources usa foreign territory 2013 revealed british officials pressured handful telecommunications internet companies allow british government gain access tat-14 according leaked documents aside five eyes western countries also participated nsa surveillance system sharing information documents nsa lists approved sigint partners partner countries addition five eyes glenn greenwald said nsa often maintains partnerships paying partner develop certain technologies engage surveillance thus direct spying carried partner countries divided two groups second parties third parties second parties comprehensive cooperation nsa third parties focused cooperation however partner nsa automatically exempt country targeted nsa according internal nsa document leaked snowden nsa often target signals 3rd party foreign partners australian signals directorate asd formerly known defence signals directorate dsd shares information australian citizens members ukusa agreement according 2008 five eyes document leaked snowden data australian citizens shared foreign countries include bulk unselected unminimised metadata well medical legal religious information close cooperation members five eyes community asd runs secret surveillance facilities many parts southeast asia without knowledge australian diplomats addition asd cooperates security intelligence division sid republic singapore international operation intercept underwater telecommunications cables across eastern hemisphere pacific ocean march 2017 reported advice five eyes intelligence alliance 500 iraqi syrian refugees refused entry australia last year communications security establishment canada csec offers nsa resources advanced collection processing analysis set covert sites request nsa us-canada signt relationship dates back secret alliance formed world war ii formalized 1949 canusa agreement behalf nsa csec opened secret surveillance facilities 20 countries around world well communications security establishment canada revealed following global surveillance disclosures engaging surveillance wifi hotspots major canadian airports collecting meta-data use engaging surveillance travelers even days departure said airports politiets efterretningstjeneste pet denmark domestic intelligence agency exchanges data nsa regular basis part secret agreement united states one 9-eyes ukusa agreement denmark relationship nsa closer nsa relationship germany sweden spain belgium italy directorate-general external security dgse france maintains close relationship nsa gchq discussions increased cooperation began november 2006 early 2010s extent cooperation joint interception digital data dgse nsa noted increased dramatically 2011 formal memorandum data exchange signed dgse nsa facilitated transfer millions metadata records dgse nsa december 2012 8 january 2013 70 million metadata records handed nsa french intelligence agencies bundesnachrichtendienst bnd germany systematically transfers metadata german intelligence sources nsa december 2012 alone bnd provided nsa 500 million metadata records nsa granted bundesnachrichtendienst access x-keyscore exchange german surveillance programs mira4 veras early 2013 hans-georg maaßen president german domestic security agency bundesamt für verfassungsschutz bfv made several visits headquarters nsa according classified documents german government maaßen agreed transfer data records persons monitored germany bfv via xkeyscore nsa addition bfv works closely eight u.s. government agencies including cia project 6 jointly operated cia bfv bnd massive database containing personal information photos license plate numbers internet search histories telephone metadata developed gain better understanding social relationships presumed jihadists 2012 bfv handed 864 data sets personal information cia nsa seven u.s. intelligence agencies exchange bnd received data u.s. intelligence agencies 1,830 occasions newly acquired data handed bfv stored domestically accessible system known nadis wn israeli sigint national unit isnu routinely receives raw unfiltered data u.s. citizens nsa however secret nsa document leaked snowden revealed u.s. government officials explicitly exempted forms data sharing isnu stated memorandum detailing rules data sharing u.s. citizens isnu obligated according undated memorandum ground rules intelligence sharing nsa isnu laid march 2009 data sharing agreement isnu allowed retain identities u.s. citizens excluding u.s. government officials year 2011 nsa asked japanese government intercept underwater fibre-optic cables carrying phone internet data asia-pacific region however japanese government refused comply reign muammar gaddafi libyan regime forged partnership britain secret service mi6 u.s. central intelligence agency cia obtain information libyan dissidents living united states canada exchange gaddafi allowed western democracies use libya base extraordinary renditions algemene inlichtingen en veiligheidsdienst aivd netherlands receiving storing data internet users gathered u.s. intelligence sources nsa prism surveillance program meeting february 2013 aivd mivd briefed nsa attempts hack internet forums collect data users using technology known computer network exploitation cne norwegian intelligence service nis confirmed data collected agency shared americans kjell grandhagen head norwegian military intelligence told reporters news conference share information partners partners share us ... talking huge amounts traffic data cooperation nsa nis gained access russian targets kola peninsula civilian targets general nis provides information nsa politicians energy armament top secret memo nsa lists following years milestones norway-united states america signt agreement norus agreement nsa perceives nis one reliable partners agencies also cooperate crack encryption systems mutual targets according nsa norway made objections requests defence ministry singapore security intelligence division sid secretly intercepting much fibre optic cable traffic passing asian continent close cooperation australian signals directorate asd/dsd singapore sid able intercept sea-me-we 3 southeast asia-middle east-western europe 3 well sea-me-we 4 telecommunications cables access international telecommunications channels facilitated singapore government-owned operator singtel temasek holdings multibillion-dollar sovereign wealth fund majority stake singtel maintained close relations country intelligence agencies information gathered government singapore transferred government australia part intelligence sharing agreement allows five eyes maintain stranglehold communications across eastern hemisphere close cooperation centro nacional de inteligencia cni nsa intercepted 60.5 million phone calls spain single month försvarets radioanstalt fra sweden codenamed sardines allowed five eyes access underwater cables baltic sea 5 december 2013 sveriges television swedish television revealed fra conducting clandestine surveillance operation targeting internal politics russia operation conducted behalf nsa receives data handed fra according documents leaked snowden fra sweden granted access nsa international surveillance program xkeyscore federal intelligence service ndb switzerland exchanges information nsa regularly basis secret agreement circumvent domestic surveillance restrictions addition nsa granted access swiss surveillance facilities leuk canton valais herrenschwanden canton bern part swiss surveillance program onyx according ndb agency maintains working relationships 100 international organizations however ndb denied form cooperation nsa although nsa direct access switzerland onyx surveillance program director ndb acknowledged possible u.s. intelligence agencies gain access switzerland surveillance system british government allowed nsa store personal data british citizens project minaret anti-vietnam war dissidents united states jointly targeted gchq nsa cia pays us 10 million year gain access international phone records including u.s. citizens nsa foreign affairs directorate interacts foreign intelligence services members five eyes implement global surveillance fbi acts liaison u.s. intelligence agencies silicon valley giants microsoft early 2010s dhs conducted joint surveillance operation fbi crack dissidents occupy wall street protest movement nsa supplies domestic intercepts drug enforcement administration dea internal revenue service irs law enforcement agencies use intercepted data initiate criminal investigations us citizens federal agents instructed recreate investigative trail order cover information originated weeks september 11 attacks u.s. president george w. bush signed patriot act ensure disruption government ability conduct global surveillance patriot act extended u.s. president barack obama may 2011 extend federal government legal authority conduct additional forms surveillance roving wiretaps 70 percent united states intelligence community budget earmarked payment private firms according forbes magazine defense technology company lockheed martin currently usa biggest defense contractor destined nsa powerful commercial partner biggest contractor terms dollar revenue joint operation nsa american telecommunications corporation operates room 641a sbc communications building san francisco spy internet traffic cia pays us 10 million year gain access international phone records including u.s. citizens projects developed booz allen hamilton include strategic innovation group identify terrorists social media behalf government agencies fiscal year 2013 booz allen hamilton derived 99 income government largest portion revenue coming u.s. army 2013 booz allen hamilton hailed bloomberg businessweek world profitable spy organization british telecommunications code-named remedy major supplier telecommunications granted britain intelligence agency gchq unlimited access network undersea cables according documents leaked snowden american multinational corporation microsoft helped nsa circumvent software encryption safeguards also allowed federal government monitor web chats outlook.com portal 2013 microsoft worked fbi allow nsa gain access company cloud storage service skydrive french telecommunications corporation orange s.a. shares customer call data french intelligence agency dgse intercepted data handed gchq rsa security paid us 10 million nsa introduce cryptographic backdoor encryption products strategic forecasting inc. commonly known stratfor global intelligence company offering information governments private clients including dow chemical company lockheed martin northrop grumman raytheon u.s. department homeland security u.s. defense intelligence agency u.s. marine corps british telecommunications company vodafone code-named gerontic granted britain intelligence agency gchq unlimited access network undersea cables according documents leaked snowden in-q-tel receives us 56 million year government support venture capital firm enables cia invest silicon valley palantir technologies data mining corporation close ties fbi nsa cia based palo alto california company developed data collection analytical program known prism 2011 revealed company conducted surveillance glenn greenwald several countries evaded global surveillance constructing secret bunker facilities deep earth surface despite north korea priority target nsa internal documents acknowledged know much kim jong un regime intentions october 2012 iran police chief esmail ahmadi moghaddam alleged google search engine spying tool western intelligence agencies six months later april 2013 country announced plans introduce islamic google earth evade global surveillance libya evaded surveillance building hardened buried bunkers least 40 feet ground level global surveillance disclosure caused tension bilateral relations united states several allies economic partners well relationship european union 12 august 2013 president obama announced creation independent panel outside experts review nsa surveillance programs panel due established director national intelligence james r. clapper consult provide assistance according survey undertaken human rights group pen international disclosures chilling effect american writers fearing risk targeted government surveillance 28 pen american members curbed usage social media 16 self-censored avoiding controversial topics writings
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Computer security
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comparison programming languages list comprehension list comprehension syntactic construct available programming languages creating list based existing lists follows form mathematical set-builder notation set comprehension distinct use map filter functions list doubles 0 10 exclusive list names customers based rio de janeiro previous code syntactic sugar following code written using lambda expressions filtering numbers divisible 3 multiple generators infinite lazy sequence list comprehension using multiple generators list comprehensions expressed codice_1 macro codice_2 keyword conditionals expressed codice_3 follows list names customers list customers balances list names customers balances general forms note putting condition expression variable name enumerable object editors ides provide autocompletion members variable lazily-evaluated sequences floating point values lists arrays list comprehensions part greater family language constructs called computation expressions example list comprehension using multiple generators using range object io language create list easy languages list comprehensions expressed codice_4 special form conditionals expressed codice_3 follows java 8 introduces new streams api includes intstream interface allows operations like following julia supports comprehensions using syntax multidimensional comprehensions like 2*i 1..100 i*i 3 multiple generators ocaml supports list comprehension ocaml batteries 2 ** 2 3 0 .. 99 python uses following syntax express list comprehensions finite lists generator expression may used python versions 2.4 gives lazy evaluation input used generators iterate 'infinite input count generator function returns successive integers subsequent use generator expression determine stop generating values example multiple generators using for-comprehension list comprehensions supported scheme use srfi-42 library example list comprehension using multiple generators 2*x || x list :getmember_nd l x*x 3 short-hand notation
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Programming language topics
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sndio sndio software layer openbsd operating system manages sound cards midi ports provides optional sound server documented application programming interface access either server audio midi hardware uniform way sndio designed work desktop applications pays special attention synchronization mechanisms reliability required music applications audio midi server main component sndio aims fill gap programs requirements bare hardware exposed operating system device drivers includes last points hooks sound server aiming improve interoperability audio midi programs use standard midi protocols volume synchronization control enables interoperability midi software hardware connected computer minimal server capabilities added —an audio stream manipulation tool predecessor —in october 2008 shipping openbsd 4.5 december 2011 renamed later shipped openbsd 5.1 default sound server started operating system boot
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Operating systems
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ibm blue gene blue gene ibm project aimed designing supercomputers reach operating speeds petaflops pflops range low power consumption project created three generations supercomputers blue gene/l blue gene/p blue gene/q blue gene systems often led top500 green500 rankings powerful power efficient supercomputers respectively blue gene systems also consistently scored top positions graph500 list project awarded 2009 national medal technology innovation 2015 ibm seems ended development blue gene family though public announcement made ibm continuing efforts supercomputer scene seems concentrated around openpower using accelerators fpgas gpus battle end moore law december 1999 ibm announced us 100 million research initiative five-year effort build massively parallel computer applied study biomolecular phenomena protein folding project two main goals advance understanding mechanisms behind protein folding via large-scale simulation explore novel ideas massively parallel machine architecture software major areas investigation included use novel platform effectively meet scientific goals make massively parallel machines usable achieve performance targets reasonable cost novel machine architectures initial design blue gene based early version cyclops64 architecture designed monty denneau initial research development work pursued ibm t.j. watson research center led william r. pulleyblank ibm alan gara started working extension qcdoc architecture general-purpose supercomputer 4d nearest-neighbor interconnection network replaced network supporting routing messages node parallel i/o subsystem added doe started funding development system became known blue gene/l l light development original blue gene system continued name blue gene/c c cyclops later cyclops64 november 2004 16-rack system rack holding 1,024 compute nodes achieved first place top500 list linpack performance 70.72 tflops thereby overtook nec earth simulator held title fastest computer world since 2002 2004 2007 blue gene/l installation llnl gradually expanded 104 racks achieving 478 tflops linpack 596 tflops peak llnl bluegene/l installation held first position top500 list 3.5 years june 2008 overtaken ibm cell-based roadrunner system los alamos national laboratory first system surpass 1 petaflops mark system built rochester mn ibm plant llnl installation largest blue gene/l installation many smaller installations followed november 2006 27 computers top500 list using blue gene/l architecture computers listed architecture eserver blue gene solution example three racks blue gene/l housed san diego supercomputer center top500 measures performance single benchmark application linpack blue gene/l also set records performance wider set applications blue gene/l first supercomputer ever run 100 tflops sustained real-world application namely three-dimensional molecular dynamics code ddcmd simulating solidification nucleation growth processes molten metal high pressure temperature conditions achievement 2005 gordon bell prize june 2006 nnsa ibm announced blue gene/l achieved 207.3 tflops quantum chemical application qbox supercomputing 2006 blue gene/l awarded winning prize hpc challenge classes awards 2007 team ibm almaden research center university nevada ran artificial neural network almost half complex brain mouse equivalent second network run 1/10 normal speed 10 seconds name blue gene comes originally designed help biologists understand processes protein folding gene development blue traditional moniker ibm uses many products company original blue gene design renamed blue gene/c eventually cyclops64 l blue gene/l comes light design original name blue light p version designed petascale design q letter p blue gene/r blue gene/l supercomputer unique following aspects blue gene/l architecture evolution qcdsp qcdoc architectures blue gene/l compute i/o node single asic associated dram memory chips asic integrated two 700 mhz powerpc 440 embedded processors double-pipeline-double-precision floating point unit fpu cache sub-system built-in dram controller logic support multiple communication sub-systems dual fpus gave blue gene/l node theoretical peak performance 5.6 gflops gigaflops two cpus cache coherent one another compute nodes packaged two per compute card 16 compute cards plus 2 i/o nodes per node board 32 node boards per cabinet/rack integration essential sub-systems single chip use low-power logic compute i/o node dissipated low power 17 watts including drams allowed aggressive packaging 1024 compute nodes plus additional i/o nodes standard 19-inch rack within reasonable limits electrical power supply air cooling performance metrics terms flops per watt flops per floorspace flops per unit cost allowed scaling high performance many nodes component failures inevitable system able electrically isolate faulty components granularity half rack 512 compute nodes allow machine continue run blue gene/l node attached three parallel communications networks 3d toroidal network peer-to-peer communication compute nodes collective network collective communication broadcasts reduce operations global interrupt network fast barriers i/o nodes run linux operating system provided communication storage external hosts via ethernet network i/o nodes handled filesystem operations behalf compute nodes finally separate private ethernet network provided access node configuration booting diagnostics allow multiple programs run concurrently blue gene/l system could partitioned electronically isolated sets nodes number nodes partition positive integer power 2 least 2 32 nodes run program blue gene/l partition computer first reserved program loaded run nodes within partition program could access nodes within partition use upon completion partition nodes released future programs use blue gene/l compute nodes used minimal operating system supporting single user program subset posix calls supported one process could run time node co-processor mode—or one process per cpu virtual mode programmers needed implement green threads order simulate local concurrency application development usually performed c c++ fortran using mpi communication however scripting languages ruby python ported compute nodes june 2007 ibm unveiled blue gene/p second generation blue gene series supercomputers designed collaboration included ibm llnl argonne national laboratory leadership computing facility design blue gene/p technology evolution blue gene/l blue gene/p compute chip contains four powerpc 450 processor cores running 850 mhz cores cache coherent chip operate 4-way symmetric multiprocessor smp memory subsystem chip consists small private l2 caches central shared 8 mb l3 cache dual ddr2 memory controllers chip also integrates logic node-to-node communication using network topologies blue gene/l twice bandwidth compute card contains blue gene/p chip 2 4 gb dram comprising compute node single compute node peak performance 13.6 gflops 32 compute cards plugged air-cooled node board rack contains 32 node boards thus 1024 nodes 4096 processor cores using many small low-power densely packaged chips blue gene/p exceeded power efficiency supercomputers generation 371 mflops/w blue gene/p installations ranked near top green500 lists 2007-2008 following incomplete list blue gene/p installations per november 2009 top500 list contained 15 blue gene/p installations 2-racks 2048 nodes 8192 processor cores 23.86 tflops linpack larger third supercomputer design blue gene series blue gene/q peak performance 20 petaflops reaching linpack benchmarks performance 17 petaflops blue gene/q continues expand enhance blue gene/l /p architectures blue gene/q compute chip 18 core chip 64-bit a2 processor cores 4-way simultaneously multithreaded run 1.6 ghz processor core simd quad-vector double precision floating point unit ibm qpx 16 processor cores used computing 17th core operating system assist functions interrupts asynchronous i/o mpi pacing ras 18th core used redundant spare used increase manufacturing yield spared-out core shut functional operation processor cores linked crossbar switch 32 mb edram l2 cache operating half core speed l2 cache multi-versioned supporting transactional memory speculative execution hardware support atomic operations l2 cache misses handled two built-in ddr3 memory controllers running 1.33 ghz chip also integrates logic chip-to-chip communications 5d torus configuration 2gb/s chip-to-chip links blue gene/q chip manufactured ibm copper soi process 45 nm delivers peak performance 204.8 gflops 1.6 ghz drawing 55 watts chip measures 19×19 mm 359.5 mm² comprises 1.47 billion transistors chip mounted compute card along 16 gb ddr3 dram i.e. 1 gb user processor core q32 compute drawer contains 32 compute cards water cooled midplane crate contains 16 q32 compute drawers total 512 compute nodes electrically interconnected 5d torus configuration 4x4x4x4x2 beyond midplane level connections optical racks two midplanes thus 32 compute drawers total 1024 compute nodes 16,384 user cores 16 tb ram separate i/o drawers placed top rack separate rack air cooled contain 8 compute cards 8 pcie expansion slots infiniband 10 gigabit ethernet networking time blue gene/q system announcement november 2011 initial 4-rack blue gene/q system 4096 nodes 65536 user processor cores achieved 17 top500 list 677.1 teraflops linpack outperforming original 2007 104-rack bluegene/l installation described 4-rack system achieved top position graph500 list 250 gteps giga traversed edges per second blue gene/q systems also topped green500 list energy efficient supercomputers 2.1 gflops/w june 2012 blue gene/q installations took top positions three lists top500 graph500 green500 following incomplete list blue gene/q installations per june 2012 top500 list contained 20 blue gene/q installations 1/2-rack 512 nodes 8192 processor cores 86.35 tflops linpack larger size-independent power efficiency 2.1 gflops/w systems also populated top june 2012 green 500 list record-breaking science applications run bg/q first cross 10 petaflops sustained performance cosmology simulation framework hacc achieved almost 14 petaflops 3.6 trillion particle benchmark run cardioid code models electrophysiology human heart achieved nearly 12 petaflops near real-time simulation sequoia fully compressible flow solver also achieved 14.4 pflop/s originally 11 pflop/s sequoia 72 machine nominal peak performance
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Computer architecture
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holistic information security practitioner holistic information security practitioner certification course integration course provides practical education integration best practices information security management information systems auditing multiple regulatory compliance requirements well map multiple regulatory requirements internationally accepted framework iso/iec 27002 class introduces iso/iec 27002:2013 cobit coso itil explains methodology map regulations data protection act 1998 uk eu directive privacy basel ii hipaa u.s. federal financial institutions examination council glb act fips 200 sarbanes-oxley fact act pci data security california sb 1386 osfi pipeda pipa canadian bill c-168 iso 27002 framework holistic information security practitioner hisp certification course originally authored efortresses inc. atlanta georgia-based cyber security governance risk management compliance solutions company specializing information security regulatory compliance training aspect hisp certification course delivered efortresses number authorized training partners including bsi management systems currently training certification aspect managed exclusively holistic information security practitioner institute independently run organization holistic information security practitioner institute also oversight body cloud assurance assessor program caap caap provides assurance qualifications purporting necessary skills independent cloud assessors
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Computer security
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microsoft azure microsoft azure formerly windows azure cloud computing service created microsoft building testing deploying managing applications services microsoft-managed data centers provides software service saas platform service paas infrastructure service iaas supports many different programming languages tools frameworks including microsoft-specific third-party software systems azure announced october 2008 started codename project red dog released february 1 2010 windows azure renamed microsoft azure march 25 2014 microsoft lists 600 azure services covered microsoft azure service bus allows applications running azure premises premises devices communicate azure helps build scalable reliable applications service-oriented architecture soa azure service bus supports four different types communication mechanisms paas offering used encoding content protection streaming analytics global content delivery network cdn audio video applications images static files used cache static assets websites geographically closer users increase performance network managed rest based http api azure 54 point presence locations worldwide also known edge locations august 2018 azure blockchain workbench microsoft providing required infrastructure setup consortium network multiple topologies using variety consensus mechanisms microsoft provides integration blockchain platforms microsoft services streamline development distributed applications microsoft supports many general-purpose blockchains including ethereum hyperledger fabric purpose-built blockchains like corda azure functions used serverless computing architectures subscribers execute code function-as-a-service faas without managing underlying server resources azure generally available 42 regions around world microsoft announced additional 12 regions opened soon october 2018 microsoft first hyper-scale cloud provider committed building facilities continent africa two regions located south africa azure geography contains multiple azure regions example “ north europe ” dublin ireland “ west europe ” amsterdam netherlands location represents city area azure region azure region paired another region within geography makes regional pair example amsterdam dublin locations form regional-pair microsoft gold partners available across globe sell products august 2018 toyota tsusho began partnership microsoft create fish farming tools using microsoft azure application suite iot technologies related water management developed part researchers kindai university water pump mechanisms use artificial intelligence count number fish conveyor belt analyze number fish deduce effectiveness water flow data fish provide specific computer programs used process fall azure machine learning azure iot hub platforms microsoft azure uses specialized operating system called microsoft azure run fabric layer cluster hosted microsoft data centers manages computing storage resources computers provisions resources subset applications running top microsoft azure microsoft azure described cloud layer top number windows server systems use windows server 2008 customized version hyper-v known microsoft azure hypervisor provide virtualization services scaling reliability controlled microsoft azure fabric controller ensures services environment fail one servers fails within microsoft data center also provides management user web application memory allocation load balancing azure provides api built rest http xml allows developer interact services provided microsoft azure microsoft also provides client-side managed class library encapsulates functions interacting services also integrates microsoft visual studio git eclipse addition interacting services via api users manage azure services using web-based azure portal reached general availability december 2015 portal allows users browse active resources modify settings launch new resources view basic monitoring data active virtual machines services advanced azure management services available microsoft azure offers two deployment models cloud resources classic deployment model azure resource manager classic model azure resource virtual machine sql database etc managed individually azure resource manager introduced 2014 enables users create groups related services closely coupled resources deployed managed monitored together microsoft stated per usa patriot act us government could access data even hosted company american data resides outside usa however microsoft azure compliant e.u data protection directive 95/46/ec manage privacy security-related concerns microsoft created microsoft azure trust center microsoft azure several services compliant several compliance programs including hipaa full current listing found microsoft azure trust center compliance page special note microsoft azure granted jab provisional authority operate p-ato u.s. government accordance guidelines spelled federal risk authorization management program fedramp u.s. government program provides standardized approach security assessment authorization continuous monitoring cloud services used federal government following list microsoft azure outages service disruptions
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Distributed computing architecture
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benjamin c. pierce benjamin crawford pierce henry salvatori professor computer science university pennsylvania pierce joined penn 1998 indiana university held research positions university cambridge university edinburgh received ph.d. carnegie mellon university 1991 research includes work programming languages static type systems distributed programming mobile agents process calculi part research pierce led development several open-source software projects including unison file synchronization utility author one book type systems types programming languages also edited collection articles create second volume advanced topics types programming languages based notes collected learning category theory phd also published introductory book topic— basic category theory computer scientists one authors freely available book software foundations
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Programming language topics
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monkey http server monkey http server optimized web server linux designed achieve high performance high loads making linux kernel terms specific system calls optimization techniques http/1.1 compliant rfc 2616 supports common features ipv6 tls virtual hosts cgi fastcgi directory listing security rules server designed small core extensible plugin interface binary size monkey around 100 kb around 250 kb runtime depending loaded plugins monkey perform well x86 x86-64 arm architectures running linux embedded variants monkey started 2001 open source project currently licensed apache license v2 monkey community well established available mailing list freenode irc channel monkey
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Web technology
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national security database national security database official accreditation program india awarded information security experts deemed credible trustworthy proven skills protect national critical infrastructure economy country program developed 'information sharing analysis center isac jointly support government india multiple speciality domains information security professionals apply empanelment database clearing technical lab examination psychometric test program award certification provides credible recognition form empanelment database specific security domain project conceived 2008 mumbai attacks protect national critical infrastructure cyber space india program founded rajshekhar murthy non-profit section 25 company 'information sharing analysis center support highly specialised technical intelligence agency ntro government india earlier program announced pilot international malware conference malcon 2010 mumbai indian government officials reportedly asked indian hackers learn chinese program released 26 november date 2008 mumbai attacks international malware conference malcon jw marriott mumbai program inaugurated shri sachin pilot minister state ministry communications information technology empanelment database applied indian citizens limited access available industry benefit list credible experts however major part database access restricted supporting indian government organisations 'the program largely believed identify professional ethical hackers security experts government india protect critical infrastructure cyber space minister kapil sibal reportedly expressed need community ethical hackers alok vijayant director information dominance group national technical research organisation nation ’ chief technical intelligence monitoring authority quoted interview india top weekly magazine outlook nsd “ trivialised ” describing group hackers “ supported government industry nsd good initiative since provide readymade database credible security professionals information security domain individuals skills companies tend regularly move one firm another nsd officially endorsed multiple indian government organisations cert-in ntro stated national objectives recognition foundation declared support work done collaboration open supporting organisations need access database formal mou body various organisations actively participating supporting national security database notable organisations voluntary representations governing nsd advisory panel national level include honeynet india chapter microsoft india country oldest security conference clubhack national security database program following speciality domains professionals apply empanelment quote outlook magazine director isac rajshekhar murthy stated necessary people competent also high degree trustworthiness integrity selection process involve examination references technical skills criminal history even psychological assessment generate credit report security clearance. ” national security database academy national security database certification ethical hacking penetration testing kali
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Databases
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alexandre oliva alexandre alex oliva brazilian free software activist developer founding member free software foundation latin america fsfla currently on-hold phd studies institute computing state university campinas brazil whilst working compiler engineer red hat contributing gcc compiler maintainer linux-libre fork linux kernel removes non-free software components binary blobs kernel linux-libre kernels used linux distributions gnewsense trisquel blag recommended free software foundation gnu project 2008 oliva translated produced porco e caixa brazilian portuguese translation pig box creative commons-licensed book teaches perils drm children 10,000 copies eventually printed fisl conference porto alegre brazil official gnu free software speaker
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Operating systems
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kgb archiver kgb archiver discontinued file archiver data compression utility employs paq6 compression algorithm written visual c++ tomasz pawlak kgb archiver designed achieve high compression ratio ten levels compression weak maximum however higher compression levels time required compress file increases significantly consequence program uses memory cpu intensively kgb archiver free open-source released terms gnu general public license version 2 beta 2 available microsoft windows command-line version kgb archiver 1.0 available unix-like operating systems minimum requirements running kgb archiver
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Computer file systems
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cryptanalysis cryptanalysis greek kryptós hidden analýein loosen untie study analyzing information systems order study hidden aspects systems cryptanalysis used breach cryptographic security systems gain access contents encrypted messages even cryptographic key unknown addition mathematical analysis cryptographic algorithms cryptanalysis includes study side-channel attacks target weaknesses cryptographic algorithms instead exploit weaknesses implementation even though goal methods techniques cryptanalysis changed drastically history cryptography adapting increasing cryptographic complexity ranging pen-and-paper methods past machines like british bombes colossus computers bletchley park world war ii mathematically advanced computerized schemes present methods breaking modern cryptosystems often involve solving carefully constructed problems pure mathematics best-known integer factorization given encrypted data ciphertext goal cryptanalyst gain much information possible original unencrypted data plaintext useful consider two aspects achieving first breaking system — discovering encipherment process works second solving key unique particular encrypted message group messages attacks classified based type information attacker available basic starting point normally assumed purposes analysis general algorithm known shannon maxim enemy knows system — turn equivalent kerckhoffs principle reasonable assumption practice — throughout history countless examples secret algorithms falling wider knowledge variously espionage betrayal reverse engineering occasion ciphers broken pure deduction example german lorenz cipher japanese purple code variety classical schemes attacks also characterised resources require resources include sometimes difficult predict quantities precisely especially attack n't practical actually implement testing academic cryptanalysts tend provide least estimated order magnitude attacks difficulty saying example sha-1 collisions 2 bruce schneier notes even computationally impractical attacks considered breaks breaking cipher simply means finding weakness cipher exploited complexity less brute force never mind brute-force might require 2 encryptions attack requiring 2 encryptions would considered break ... simply put break certificational weakness evidence cipher perform advertised results cryptanalysis also vary usefulness example cryptographer lars knudsen 1998 classified various types attack block ciphers according amount quality secret information discovered academic attacks often weakened versions cryptosystem block cipher hash function rounds removed many attacks become exponentially difficult execute rounds added cryptosystem possible full cryptosystem strong even though reduced-round variants weak nonetheless partial breaks come close breaking original cryptosystem may mean full break follow successful attacks des md5 sha-1 preceded attacks weakened versions academic cryptography weakness break scheme usually defined quite conservatively might require impractical amounts time memory known plaintexts also might require attacker able things many real-world attackers ca n't example attacker may need choose particular plaintexts encrypted even ask plaintexts encrypted using several keys related secret key furthermore might reveal small amount information enough prove cryptosystem imperfect little useful real-world attackers finally attack might apply weakened version cryptographic tools like reduced-round block cipher step towards breaking full system cryptanalysis coevolved together cryptography contest traced history cryptography—new ciphers designed replace old broken designs new cryptanalytic techniques invented crack improved schemes practice viewed two sides coin secure cryptography requires design possible cryptanalysis successful cryptanalysis undoubtedly influenced history ability read presumed-secret thoughts plans others decisive advantage example england 1587 mary queen scots tried executed treason result involvement three plots assassinate elizabeth england plans came light coded correspondence fellow conspirators deciphered thomas phelippes world war breaking zimmermann telegram instrumental bringing united states war world war ii allies benefitted enormously joint success cryptanalysis german ciphers — including enigma machine lorenz cipher — japanese ciphers particularly 'purple jn-25 'ultra intelligence credited everything shortening end european war two years determining eventual result war pacific similarly helped 'magic intelligence governments long recognized potential benefits cryptanalysis intelligence military diplomatic established dedicated organizations devoted breaking codes ciphers nations example gchq nsa organizations still active today 2004 reported united states broken iranian ciphers unknown however whether pure cryptanalysis whether factors involved although actual word cryptanalysis relatively recent coined william friedman 1920 methods breaking codes ciphers much older first known recorded explanation cryptanalysis given 9th-century arab polymath al-kindi also known alkindus europe manuscript deciphering cryptographic messages treatise includes description method frequency analysis ibrahim al-kadi 1992- ref-3 italian scholar giambattista della porta author seminal work cryptanalysis de furtivis literarum notis frequency analysis basic tool breaking classical ciphers natural languages certain letters alphabet appear often others english e likely common letter sample plaintext similarly digraph th likely pair letters english frequency analysis relies cipher failing hide statistics example simple substitution cipher letter simply replaced another frequent letter ciphertext would likely candidate e frequency analysis cipher therefore relatively easy provided ciphertext long enough give reasonably representative count letters alphabet contains europe 15th 16th centuries idea polyalphabetic substitution cipher developed among others french diplomat blaise de vigenère 1523–96 three centuries vigenère cipher uses repeating key select different encryption alphabets rotation considered completely secure le chiffre indéchiffrable — indecipherable cipher nevertheless charles babbage 1791–1871 later independently friedrich kasiski 1805–81 succeeded breaking cipher world war inventors several countries developed rotor cipher machines arthur scherbius enigma attempt minimise repetition exploited break vigenère system cryptanalysis enemy messages played significant part allied victory world war ii f. w. winterbotham quoted western supreme allied commander dwight d. eisenhower war end describing ultra intelligence decisive allied victory sir harry hinsley official historian british intelligence world war ii made similar assessment ultra saying shortened war less two years probably four years moreover said absence ultra uncertain war would ended practice frequency analysis relies much linguistic knowledge statistics ciphers became complex mathematics became important cryptanalysis change particularly evident world war ii efforts crack axis ciphers required new levels mathematical sophistication moreover automation first applied cryptanalysis era polish bomba device british bombe use punched card equipment colossus computers — first electronic digital computers controlled program reciprocal machine ciphers lorenz cipher enigma machine used nazi germany world war ii message key usually transmitting operator informed receiving operator message key transmitting plaintext and/or ciphertext enciphered message termed indicator indicates receiving operator set machine decipher message poorly designed implemented indicator systems allowed first polish cryptographers british cryptographers bletchley park break enigma cipher system similar poor indicator systems allowed british identify depths led diagnosis lorenz sz40/42 cipher system comprehensive breaking messages without cryptanalysts seeing cipher machine sending two messages key insecure process cryptanalyst messages said depth may detected messages indicator sending operator informs receiving operator key generator initial settings message generally cryptanalyst may benefit lining identical enciphering operations among set messages example vernam cipher enciphers bit-for-bit combining plaintext long key using exclusive operator also known modulo-2 addition symbolized ⊕ deciphering combines key bits ciphertext reconstruct plaintext modulo-2 arithmetic addition subtraction two ciphertexts aligned depth combining eliminates common key leaving combination two plaintexts individual plaintexts worked linguistically trying probable words phrases also known cribs various locations correct guess combined merged plaintext stream produces intelligible text plaintext component recovered fragment second plaintext often extended one directions extra characters combined merged plaintext stream extend first plaintext working back forth two plaintexts using intelligibility criterion check guesses analyst may recover much original plaintexts two plaintexts depth analyst may know one corresponds ciphertext practice large problem recovered plaintext combined ciphertext key revealed knowledge key course allows analyst read messages encrypted key knowledge set related keys may allow cryptanalysts diagnose system used constructing even though computation used great effect cryptanalysis lorenz cipher systems world war ii also made possible new methods cryptography orders magnitude complex ever taken whole modern cryptography become much impervious cryptanalysis pen-and-paper systems past seems upper hand pure cryptanalysis historian david kahn notes kahn goes mention increased opportunities interception bugging side channel attacks quantum computers replacements traditional means cryptanalysis 2010 former nsa technical director brian snow said academic government cryptographers moving slowly forward mature field however postmortems cryptanalysis may premature effectiveness cryptanalytic methods employed intelligence agencies remains unknown many serious attacks academic practical cryptographic primitives published modern era computer cryptography thus best modern ciphers may far resistant cryptanalysis enigma cryptanalysis broader field information security remain quite active asymmetric cryptography public key cryptography cryptography relies using two mathematically related keys one private one public ciphers invariably rely hard mathematical problems basis security obvious point attack develop methods solving problem security two-key cryptography depends mathematical questions way single-key cryptography generally conversely links cryptanalysis wider mathematical research new way asymmetric schemes designed around conjectured difficulty solving various mathematical problems improved algorithm found solve problem system weakened example security diffie–hellman key exchange scheme depends difficulty calculating discrete logarithm 1983 coppersmith found faster way find discrete logarithms certain groups thereby requiring cryptographers use larger groups different types groups rsa security depends part upon difficulty integer factorization — breakthrough factoring would impact security rsa 1980 one could factor difficult 50-digit number expense 10 elementary computer operations 1984 state art factoring algorithms advanced point 75-digit number could factored 10 operations advances computing technology also meant operations could performed much faster moore law predicts computer speeds continue increase factoring techniques may continue well likely depend mathematical insight creativity neither ever successfully predictable 150-digit numbers kind used rsa factored effort greater unreasonable fast modern computers start 21st century 150-digit numbers longer considered large enough key size rsa numbers several hundred digits still considered hard factor 2005 though methods probably continue improve time requiring key size keep pace methods elliptic curve cryptography used another distinguishing feature asymmetric schemes unlike attacks symmetric cryptosystems cryptanalysis opportunity make use knowledge gained public key quantum computers still early phases research potential use cryptanalysis example shor algorithm could factor large numbers polynomial time effect breaking commonly used forms public-key encryption using grover algorithm quantum computer brute-force key search made quadratically faster however could countered doubling key length
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Computer security
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application-level gateway context computer networking application-level gateway also known alg application layer gateway application gateway application proxy application-level proxy consists security component augments firewall nat employed computer network allows customized nat traversal filters plugged gateway support address port translation certain application layer control/data protocols ftp bittorrent sip rtsp file transfer im applications etc order protocols work nat firewall either application know address/port number combination allows incoming packets nat monitor control traffic open port mappings firewall pinhole dynamically required legitimate application data thus passed security checks firewall nat would otherwise restricted traffic meeting limited filter criteria alg may offer following functions deep packet inspection packets handled algs given network makes functionality possible alg understands protocol used specific applications supports instance session initiation protocol sip back-to-back user agent b2bua alg allow firewall traversal sip firewall sip traffic terminated alg responsibility permitting sip sessions passes alg instead firewall alg solve another major sip headache nat traversal basically nat built-in alg rewrite information within sip messages hold address bindings session terminates sip alg also handle sdp body sip messages used ubiquitously voip set media endpoints since sdp also contains literal ip addresses ports must translated alg similar proxy server sits client real server facilitating exchange seems industry convention alg job without application configured use intercepting messages proxy hand usually needs configured client application client explicitly aware proxy connects rather real server application layer gateway service microsoft windows provides support third-party plugins allow network protocols pass windows firewall work behind internet connection sharing alg plugins open ports change data embedded packets ports ip addresses windows server 2003 also includes alg ftp plugin alg ftp plugin designed support active ftp sessions nat engine windows alg ftp plugin redirects traffic passes nat destined port 21 ftp control port private listening port 3000–5000 range microsoft loopback adapter alg ftp plugin monitors/updates traffic ftp control channel ftp plugin plumb port mappings nat ftp data channels linux kernel netfilter framework implements nat linux features modules several nat algs
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Computer security
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list web analytics software list web analytics software used collect display data visiting website users comparison table web analytics software released free software license comparison table web analytics proprietary software comparison table hosted web analytics software service
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Web technology
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deep linking context world wide web deep linking use hyperlink links specific generally searchable indexed piece web content website e.g nowiki http //example.com/path/page /nowiki rather website home page e.g. nowiki http //example.com /nowiki url contains information needed point particular item case example section english wikipedia article entitled deep linking opposed information needed point highest-level home page wikipedia codice_1 technology behind world wide web hypertext transfer protocol http actually make distinction deep links links—all links functionally equal intentional one design purposes web allow authors link published document another site possibility so-called deep linking therefore built web technology http urls default—while site attempt restrict deep links requires extra effort according world wide web consortium technical architecture group attempt forbid practice deep linking based misunderstanding technology threatens undermine functioning web whole commercial websites object sites making deep links content either bypasses advertising main pages passes content linker like wall street journal charge users permanently valid links sometimes deep linking led legal action 1997 case ticketmaster versus microsoft microsoft deep-linked ticketmaster site sidewalk service case settled microsoft ticketmaster arranged licensing agreement ticketmaster later filed similar case tickets.com judge case ruled linking legal long clear linked pages belonged court also concluded urls copyrightable writing url simply address open public like street address building known enable user reach building nothing sufficiently original make url copyrightable item especially way used appear cases holding urls subject copyright principle websites built technologies adobe flash ajax often support deep linking cause usability problems visitors sites example may unable save bookmarks individual pages states site use web browser forward back buttons—and clicking browser refresh button may return user initial page however fundamental limitation technologies well-known techniques libraries swfaddress unfocus history keeper exist website creators using flash ajax use provide deep linking pages within sites probably earliest legal case arising deep linking 1996 scottish case shetland times vs shetland news times accused news appropriating stories times nowiki /nowiki website beginning 2006 case search engine bixee.com job site naukri.com delhi high court india prohibited bixee.com deeplinking naukri.com important widely cited u.s. opinions deep linking ninth circuit rulings kelly v. arriba soft corp. perfect 10 inc. v. amazon.com inc. cases court exonerated use deep linking second cases court explained speaking defendant google perfect 10 also sued linking copyright infringement us law google not…display copy full-size infringing photographic images purposes copyright act google frames in-line linked images appear user computer screen google computers store photographic images google copy images purposes copyright act words google material objects…in work fixed…and work perceived reproduced otherwise communicated thus communicate copy instead communicating copy image google provides html instructions direct user browser website publisher computer stores full-size photographic image providing html instructions equivalent showing copy first html instructions lines text photographic image second html instructions cause infringing images appear user computer screen html merely gives address image user browser browser interacts computer stores infringing image interaction causes infringing image appear user computer screen google may facilitate user access infringing images however assistance raised contributory liability issues constitute direct infringement copyright owner display rights …while in-line linking framing may cause computer users believe viewing single google webpage copyright act unlike trademark act protect copyright holder acts cause consumer confusion december 2006 texas court ruled linking motocross website videos texas-based motocross video production website constitute fair use court subsequently issued injunction case sfx motor sports inc. v. davis published official reports available 2006 wl 3616983 february 2006 ruling danish maritime commercial court copenhagen found systematic crawling indexing deep linking portal site ofir.dk real estate site home.dk conflict danish law database directive european union court stated search engines desirable functioning internet publishing information internet one must assume—and accept—that search engines deep-link individual pages one website web site owners n't want search engines deep link want index specific pages request using robots exclusion standard robots.txt file people favor deep linking often feel content owners n't provide robots.txt file implying default object deep linking either search engines others people deep linking often claim content owners may unaware robots exclusion standard may use robots.txt reasons sites search engines also deep link content sites question relevance robots exclusion standard controversies deep linking robots exclusion standard programmatically enforce directives prevent search engines others follow polite conventions deep linking
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Web technology
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biometric tokenization biometric tokenization process substituting stored biometric template non-sensitive equivalent called token lacks extrinsic exploitable meaning value process combines biometrics public-key cryptography enable use stored biometric template e.g. fingerprint image mobile desktop device secure strong authentication applications systems without presenting template original replicable form biometric tokenization particular builds upon longstanding practice tokenization sequestering secrets manner secret user credentials like usernames passwords personally identifiable information pii represented substitute key public sphere technology closely associated authentication online applications running desktop computers mobile devices internet things iot nodes specific use cases include secure login payments physical access management smart connected products connected homes connected cars well adding biometric component two-factor authentication multi-factor authentication september 9 2014 launch apple pay service cupertino calif.-based apple inc. initiated conversation surrounding use biometricsupported tokenization payment data point sale retail transactions apple pay tokenizes mobile users ’ virtualized bank card data order wirelessly transmit payment represented token participating retailers support apple pay e.g partnerships supported hardware apple pay leverages proprietary touch id fingerprint scanner proprietary iphone line aside cryptography added security apple a7 system chip includes secure enclave hardware feature stores protects data touch id fingerprint sensor apple pay least payments credited innovating space biometric tokenization even use case limited payment convenience security restricted company ’ hardware software despite fact executives publicly utter phrase “ biometric tokenization ” speak underlying technology biometric tokenization apple pay similar biometric tokenization known today particularly using term verbatim authentication feature goes beyond payment convenience security distinctive features biometric tokenization implemented operating systems osx microsoft windows google android password-less login desktop mobile applications biometric tokenization like non-biometric counterpart tokenization utilizes end-to-end encryption safeguard data transit biometric tokenization user initiates authentication first accessing unlocking biometrics fingerprint recognition facial recognition system speech recognition iris recognition retinal scan combination biometric modalities user ’ unique qualities generally stored one two ways either on-device trusted execution environment tee trusted platform module tpm server way data stored biometric tokenization champions typically prefer biometric templates encrypted stored tees tpms prevent large-scale data breaches june 2015 u.s. office personnel management one biometric tokenization aided on-device storage user data also preserve internet privacy user data stored individually inside single devices rather aggregated ostensibly vulnerable servers moving biometric user credentials either two-factor authentication unqualified authentication example servers onto devices tenet fast identity online fido alliance industry consortium concerned replacing passwords decentralized biometrics next step biometric tokenization unlocking user credentials trusted area device credentials tokenized token containing precise data required action e.g login payment access token time-stamped case one-time passwords session tokens useful specific time period may biometric tokenization token validated means joint client-side server-side validation occurs challenge-response token exchange user logged authenticated otherwise granted access order achieve highest level privacy protection calculating transmitting sensitive information biometric tokenization leverages existing encryption algorithms authentication protocols well hardware trust zones combining methods maximizes level protection needed uphold integrity process security data could otherwise expose users breach trust mass scale
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Computer security
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ben laurie ben laurie software engineer protocol designer cryptographer founding director apache software foundation core team member openssl member shmoo group director open rights group director security bunker secure hosting trustee founder-member freebmd visiting fellow cambridge university computer laboratory laurie works google london various projects currently focused certificate transparency ben wrote apache-ssl basis ssl-enabled versions apache http server co-author openpgp sdk developed mud gods innovative including online creation endgame ben also written several articles papers books many found home page blog interested ideal knots applications
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Computer security
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peter landin peter john landin 5 june 1930 – 3 june 2009 british computer scientist one first realise lambda calculus could used model programming language insight essential development functional programming denotational semantics landin born sheffield attended king edward vii school graduated clare college cambridge university 1960 1964 assistant christopher strachey latter independent computer consultant london work published period brief time worked univac massachusetts institute technology united states taking position queen mary university london 1970s 1980s efforts went building computer science department queen mary college developing courses teaching students retirement appointed emeritus professor theoretical computation queen mary university london 2012 computer science building renamed peter landin building honour workshop science museum london 2001 history programming semantics spoke scholarly career computer science began late 1950s much influenced study mccarthy lisp commonly used language fortran active definition algol programming language cited tony hoare one people taught algol 60 hence facilitated expression powerful recursive algorithms around easter 1961 course algol 60 offered brighton england peter naur edsger w. dijkstra peter landin tutors ... first learned recursive procedures saw program sorting method earlier found difficulty explaining wrote procedure immodestly named quicksort career computer scientist founded due credit must paid genius designers algol 60 included recursion language enabled describe invention elegantly world regarded highest goal programming language design enable good ideas elegantly expressed landin responsible inventing secd machine first abstract machine functional programming language iswim programming language defining landin off-side rule coining term syntactic sugar off-side rule allows bounding scope declaration use white spaces seen languages miranda haskell python f using light syntax another phrase originating landin next 700 ... influential paper next 700 programming languages 700 chosen landin read journal acm already 700 programming languages existence paper opens quotation ... today ... 1,700 special programming languages used 'communicate 700 application areas also includes joke possible first step research program 1700 doctoral theses called correspondence x church λ-notation reference earlier paper dry sense humour expressed many papers landin bisexual became involved gay liberation front glf early 1970s arrested part anti-nuclear demonstration dedicated cyclist moved around london bike became physically impossible
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Programming language topics
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hosted desktop hosted desktop product set within larger cloud-computing sphere generally delivered using combination technologies including hardware virtualization form remote connection software citrix xenapp microsoft remote desktop services two common processing takes place within provider datacentre environment traffic datacentre client primarily display updates mouse movements keyboard activity additional traffic generated audio print jobs hosted desktop commonly involves browser-based connection desktop environment includes office productivity suite alongside desktop applications desktop hosted run delivered supported central location usually secure data center high-quality resilient connections internet/cloud cloud desktop term often used refer container collection virtual objects software hardware configurations etc. residing cloud used client interact remote services perform computer related tasks connecting clients run pre-installed downloaded viewer applications via one many remote desktop protocols clients include thin clients pcs workstations mobile handheld devices running variety operating systems windows mac os x linux others move towards hosted desktops virtual desktop infrastructure vdi subset predicted gartner account 49 million business desktops 2013 equal 40 percent worldwide professional pc market development applications service providers google microsoft accelerated process evolution new licensing schemes allow fee-paying based subscription rather purchase centralized nature hosted desktops overcome common issues mobile working delivery common infrastructure across physical sites disaster recovery cost control scaling up/down timely fashion hosted desktop services comparatively simple method applying outsourcing principles within business although care warranted ensuring service provider quality ensure compliance data security data protection standards meet requirements hosted desktop based environment generally migrate user authentication file print services application delivery data storage cloud making accessible via secure connections internet enabled location relatively small bandwidth requirements hosted desktop means 5 10 people connect work standard xdsl broadband whilst single user operate quite effectively 3g mobile data connection hosted desktops often based windows server 2008 utilising remote desktop services often additional management layer vendors like citrix systems parallels workstation make personalisation easier licensing type hosted desktop provided microsoft service provider license agreement spla special type end-user license agreement user rents appropriate licenses part monthly fee paid service provider receives automatic upgrade rights latest version software part agreement backup disaster recovery handled hosted desktop vendor best solutions also providing failover alternate datacentres hosted desktop vendors utilising vmware microsoft technology charges normally monthly basic charge applied user hosted desktop additional charges office productivity suite additional data storage extra applications vendors wrap suite common applications product sets simplify still
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Distributed computing architecture
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call blocking call blocking also known call block call screening call rejection allows telephone subscriber block incoming calls specific telephone numbers feature may require additional payment subscriber telephone company third-party call blocking desired individuals wish block unwanted phone calls generally include types unsolicited calls telemarketers robocalls unwanted calls landlines may blocked number methods landline phones built-in call blocking facilities external call blockers sold telephone accessories plug existing phones call blockers related services recently received attention 2016 publications including consumer reports united kingdom united states respectively devices services enable user block call progress alternatively block number call made devices rely caller id information thus phone blocker requires caller id service active line blocking function may also possible use computer software conjunction caller id information phone company caller id enabled phone modem block incoming call treatment blocked calls may include multitude third-party call blocking applications available smart phones manufacturers provide built-in call blocking functions standard
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Computer security
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xtradb percona xtradb storage engine mariadb percona server databases intended drop-in replacement innodb one default engines available mysql database 10.1 mariadb mariadb server used percona xtradb default storage engine mariadb 10.2 innodb engine default xtradb xtradb incorporates innodb acid-compliant design mvcc architecture allows greater degree tuning scalability engine also better suited multi-core processing addresses issues known innodb
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Databases
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mex file mex file type computer file provides interface matlab octave functions written c c++ fortran stands matlab executable compiled mex files dynamically loaded allow external functions invoked within matlab octave built-in functions support development mex files matlab octave offer external interface functions facilitate transfer data mex files workspace addition mex files octave format using native api better performance
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Programming language topics
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compiler compiler computer program translates computer code written one programming language source language another programming language target language name compiler primarily used programs translate source code high-level programming language lower level language e.g. assembly language object code machine code create executable program however many different types compilers compiled program run computer whose cpu operating system different one compiler runs compiler cross-compiler bootstrap compiler written language intends compile program translates low-level language higher level one decompiler program translates high-level languages usually called source-to-source compiler transpiler language rewriter usually program translates form expressions without change language term compiler-compiler refers tools used create parsers perform syntax analysis compiler likely perform many following operations preprocessing lexical analysis parsing semantic analysis syntax-directed translation conversion input programs intermediate representation code optimization code generation compilers implement operations phases promote efficient design correct transformations source input target output program faults caused incorrect compiler behavior difficult track work around therefore compiler implementers invest significant effort ensure compiler correctness compilers language processor used transform source programs interpreter computer software transforms executes indicated operations translation process influences design computer languages leads preference compilation interpretation practice interpreter implemented compiled languages compilers implemented interpreted languages theoretical computing concepts developed scientists mathematicians engineers formed basis digital modern computing development world war ii primitive binary languages evolved digital devices understand ones zeros circuit patterns underlying machine architecture late 1940s assembly languages created offer workable abstraction computer architectures limited memory capacity early computers led substantial technical challenges first compilers designed therefore compilation process needed divided several small programs front end programs produce analysis products used back end programs generate target code computer technology provided resources compiler designs could align better compilation process usually productive programmer use high-level language development high-level languages followed naturally capabilities offered digital computers high-level languages formal languages strictly defined syntax semantics form high-level language architecture elements formal languages include sentences language may defined set rules called grammar backus–naur form bnf describes syntax sentences language used syntax algol 60 john backus ideas derive context-free grammar concepts noam chomsky linguist bnf extensions become standard tools describing syntax programming notations many cases parts compilers generated automatically bnf description 1940s konrad zuse designed algorithmic programming language called plankalkül plan calculus actual implementation occurred 1970s presented concepts later seen apl designed ken iverson late 1950s apl language mathematical computations high-level language design formative years digital computing provided useful programming tools variety applications compiler technology evolved need strictly defined transformation high-level source program low-level target program digital computer compiler could viewed front end deal analysis source code back end synthesize analysis target code optimization front end back end could produce efficient target code early milestones development compiler technology early operating systems software written assembly language 60s early 70s use high-level languages system programming still controversial due resource limitations however several research industry efforts began shift toward high-level systems programming languages example bcpl bliss b c. bcpl basic combined programming language designed 1966 martin richards university cambridge originally developed compiler writing tool several compilers implemented richards book provides insights language compiler bcpl influential systems programming language still used research also provided basis design b c languages bliss basic language implementation system software developed digital equipment corporation dec pdp-10 computer w.a wulf carnegie mellon university cmu research team cmu team went develop bliss-11 compiler one year later 1970 multics multiplexed information computing service time-sharing operating system project involved mit bell labs general electric later honeywell led fernando corbató mit multics written pl/i language developed ibm ibm user group ibm goal satisfy business scientific systems programming requirements languages could considered pl/i offered complete solution even though implemented first years mulitics project subset language could compiled assembly language early pl/i epl compiler doug mcilory bob morris bell labs epl supported project boot-strapping compiler full pl/i could developed bell labs left multics project 1969 time hope replaced frustration group effort initially failed produce economically useful system continued participation would drive project support costs researchers turned development efforts system programming language b based bcpl concepts written dennis ritchie ken thompson ritchie created boot-strapping compiler b wrote unics uniplexed information computing service operating system pdp-7 b. unics eventually became spelled unix bell labs started development expansion c based b bcpl bcpl compiler transported multics bell labs bcpl preferred language bell labs initially front-end program bell labs b compiler used c compiler developed 1971 new pdp-11 provided resource define extensions b rewrite compiler 1973 design c language essentially complete unix kernel pdp-11 rewritten c. steve johnson started development portable c compiler pcc support retargeting c compilers new machines object-oriented programming oop offered interesting possibilities application development maintenance oop concepts go back part lisp simula language science bell labs development c++ became interested oop c++ first used 1980 systems programming initial design leveraged c language systems programming capabilities simula concepts object-oriented facilities added 1983 cfront program implemented c++ front-end c84 language compiler subsequent years several c++ compilers developed c++ popularity grew many application domains idea using higher-level language quickly caught expanding functionality supported newer programming languages increasing complexity computer architectures compilers became complex darpa defense advanced research projects agency sponsored compiler project wulf cmu research team 1970 production quality compiler-compiler pqcc design would produce production quality compiler pqc formal definitions source language target pqcc tried extend term compiler-compiler beyond traditional meaning parser generator e.g. yacc without much success pqcc might properly referred compiler generator pqcc research code generation process sought build truly automatic compiler-writing system effort discovered designed phase structure pqc bliss-11 compiler provided initial structure phases included analyses front end intermediate translation virtual machine middle end translation target back end tcol developed pqcc research handle language specific constructs intermediate representation variations tcol supported various languages pqcc project investigated techniques automated compiler construction design concepts proved useful optimizing compilers compilers object-oriented programming language ada ada stoneman document formalized program support environment apse along kernel kapse minimal mapse ada interpreter nyu/ed supported development standardization efforts american national standards institute ansi international standards organization iso initial ada compiler development u.s. military services included compilers complete integrated design environment along lines stoneman document army navy worked ada language system als project targeted dec/vax architecture air force started ada integrated environment aie targeted ibm 370 series projects provide desired results contribute overal effort ada development ada compiler efforts got underway britain university york germany university karlsruhe u. s. verdix later acquired rational delivered verdix ada development system vads army vads provided set development tools including compiler unix/vads could hosted variety unix platforms dec ultrix sun 3/60 solaris targeted motorola 68020 army cecom evaluation soon many ada compilers available passed ada validation tests free software foundation gnu project developed gnu compiler collection gcc provides core capability support multiple languages targets ada version gnat one widely used ada compilers gnat free also commercial support example adacore founded 1994 provide commercial software solutions ada gnat pro includes gnu gcc based gnat tool suite provide integrated development environment high-level languages continued drive compiler research development focus areas included optimization automatic code generation trends programming languages development environments influenced compiler technology compilers became included language distributions perl java development kit component ide vads eclipse ada pro interrelationship interdependence technologies grew advent web services promoted growth web languages scripting languages scripts trace back early days command line interfaces cli user could enter commands executed system user shell concepts developed languages write shell programs early windows designs offered simple batch programming capability conventional transformation language used interpreter widely used bash batch compilers written recently sophisticated interpreted languages became part developers tool kit modern scripting languages include php python ruby lua lua widely used game development interpreter compiler support field compiling began late 50s focus limited translation high-level language programs machine code ... compiler field increasingly intertwined disciplines including computer architecture programming languages formal methods software engineering computer security compiler research next 50 years article noted importance object-oriented languages java security parallel computing cited among future research targets compiler implements formal transformation high-level source program low-level target program compiler design define end end solution tackle defined subset interfaces compilation tools e.g preprocessors assemblers linkers design requirements include rigorously defined interfaces internally compiler components externally supporting toolsets early days approach taken compiler design directly affected complexity computer language processed experience person designing resources available resource limitations led need pass source code compiler relatively simple language written one person might single monolithic piece software however source language grows complexity design may split number interdependent phases separate phases provide design improvements focus development functions compilation process classifying compilers number passes background hardware resource limitations computers compiling involves performing lots work early computers enough memory contain one program work compilers split smaller programs made pass source representation performing required analysis translations ability compile single pass classically seen benefit simplifies job writing compiler one-pass compilers generally perform compilations faster multi-pass compilers thus partly driven resource limitations early systems many early languages specifically designed could compiled single pass e.g. pascal cases design language feature may require compiler perform one pass source instance consider declaration appearing line 20 source affects translation statement appearing line 10 case first pass needs gather information declarations appearing statements affect actual translation happening subsequent pass disadvantage compiling single pass possible perform many sophisticated optimizations needed generate high quality code difficult count exactly many passes optimizing compiler makes instance different phases optimization may analyse one expression many times analyse another expression splitting compiler small programs technique used researchers interested producing provably correct compilers proving correctness set small programs often requires less effort proving correctness larger single equivalent program regardless exact number phases compiler design phases assigned one three stages stages include front end middle end back end front/middle/back-end approach makes possible combine front ends different languages back ends different cpus sharing optimizations middle end practical examples approach gnu compiler collection llvm amsterdam compiler kit multiple front-ends shared optimizations multiple back-ends front end analyzes source code build internal representation program called intermediate representation ir also manages symbol table data structure mapping symbol source code associated information location type scope frontend single monolithic function program scannerless parser commonly implemented analyzed several phases may execute sequentially concurrently method favored due modularity separation concerns commonly today frontend broken three phases lexical analysis also known lexing syntax analysis also known scanning parsing semantic analysis lexing parsing comprise syntactic analysis word syntax phrase syntax respectively simple cases modules lexer parser automatically generated grammar language though complex cases require manual modification lexical grammar phrase grammar usually context-free grammars simplifies analysis significantly context-sensitivity handled semantic analysis phase semantic analysis phase generally complex written hand partially fully automated using attribute grammars phases broken lexing scanning evaluating parsing building concrete syntax tree cst parse tree transforming abstract syntax tree ast syntax tree cases additional phases used notably line reconstruction preprocessing rare main phases front end include following middle end also known optimizer performs optimizations intermediate representation order improve performance quality produced machine code middle end contains optimizations independent cpu architecture targeted main phases middle end include following compiler analysis prerequisite compiler optimization tightly work together example dependence analysis crucial loop transformation scope compiler analysis optimizations vary greatly scope may range operating within basic block whole procedures even whole program trade-off granularity optimizations cost compilation example peephole optimizations fast perform compilation affect small local fragment code performed independently context code fragment appears contrast interprocedural optimization requires compilation time memory space enable optimizations possible considering behavior multiple functions simultaneously interprocedural analysis optimizations common modern commercial compilers hp ibm sgi intel microsoft sun microsystems free software gcc criticized long time lacking powerful interprocedural optimizations changing respect another open source compiler full analysis optimization infrastructure open64 used many organizations research commercial purposes due extra time space needed compiler analysis optimizations compilers skip default users use compilation options explicitly tell compiler optimizations enabled back end responsible cpu architecture specific optimizations code generation main phases back end include following compiler correctness branch software engineering deals trying show compiler behaves according language specification techniques include developing compiler using formal methods using rigorous testing often called compiler validation existing compiler higher-level programming languages usually appear type translation mind either designed compiled language interpreted language however practice rarely anything language requires exclusively compiled exclusively interpreted although possible design languages rely re-interpretation run time categorization usually reflects popular widespread implementations language — instance basic sometimes called interpreted language c compiled one despite existence basic compilers c interpreters interpretation replace compilation completely hides user makes gradual even though interpreter interpreted directly executed program needed somewhere bottom stack see machine language compilers contain interpreters optimization reasons example expression executed compilation results inserted output program prevents recalculated time program runs greatly speed final program modern trends toward just-in-time compilation bytecode interpretation times blur traditional categorizations compilers interpreters even language specifications spell implementations must include compilation facility example common lisp however nothing inherent definition common lisp stops interpreted languages features easy implement interpreter make writing compiler much harder example apl snobol4 many scripting languages allow programs construct arbitrary source code runtime regular string operations execute code passing special evaluation function implement features compiled language programs must usually shipped runtime library includes version compiler one classification compilers platform generated code executes known target platform native hosted compiler one whose output intended directly run type computer operating system compiler runs output cross compiler designed run different platform cross compilers often used developing software embedded systems intended support software development environment output compiler produces code virtual machine vm may may executed platform compiler produced reason compilers usually classified native cross compilers lower level language target compiler may high-level programming language c viewed sort portable assembly language frequently target language compilers example cfront original compiler c++ used c target language c code generated compiler usually intended readable maintained humans indent style creating pretty c intermediate code ignored features c make good target language include codice_1 directive generated compiler support debugging original source wide platform support available c compilers common compiler type outputs machine code many types
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Programming language topics
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