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scene description language scene description language description language used describe scene rendered 3d renderer ray tracer scene written text editor may include syntax highlighting opposed modeled graphical way scene description language may include variables constants conditional statements loops loops 3dmlw x3d xml-based scene description languages tao presentations application uses xl dynamic document description language pov-ray 3dmlw x3d tao presentations
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Programming language topics
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joanna hoffman joanna karine hoffman born july 27 1953 american marketing executive one original members apple computer macintosh team next team hoffman born poland daughter film director jerzy hoffman armenian former wife marlena nazarian lived mother armenian ssr age 10 went live father warsaw poland around age 12 1967 mother married american moved buffalo new york hoffman joined united states 1968 hoffman quickly became fluent english excelled school background anthropology physics linguistics bachelor science humanities science mit pursued doctorate complete archaeology university chicago oriental institute 1979 scheduled travel iran archaeology dig stopped poland visit grandmother received word iran would return united states iranian revolution hoffman leave absence university chicago encouraged friends attend lecture xerox parc california heated discussion lecture jef raskin discussion focused computers look like improve people lives raskin impressed hoffman asked interview position apple began macintosh project october 1980 part raskin initial team burrell smith bud tribble brian howard time began mac still research project position constituted entire macintosh marketing team first year half project also wrote first draft macintosh user interface guidelines hoffman would eventually run international marketing team brought mac europe asia later followed steve jobs next one original members hoffman reputation apple next one could successfully engage jobs 1981 1982 satirical award apple given person best job standing jobs ” jobs aware award liked early 1990s hoffman vice president marketing general magic retiring 1995 spend time family occasion given public lectures discussing early life apple working steve jobs hoffman married alain rossmann native france also worked apple two sons children attended international school peninsula palo alto served school board abigail mcconnell portrayed hoffman 2013 film jobs british actress kate winslet portrayed hoffman 2015 film steve jobs winslet golden globe award best supporting actress – motion picture bafta award best actress supporting role nominated academy award best supporting actress performance nature relationship hoffman jobs winslet described jobs work wife extraordinary feisty eastern european person pretty much person could actually knock sense steve
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Operating systems
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apache thrift thrift interface definition language binary communication protocol used defining creating services numerous languages forms remote procedure call rpc framework developed facebook scalable cross-language services development combines software stack code generation engine build cross-platform services connect applications written variety languages frameworks including actionscript c c++ c cappuccino cocoa delphi erlang go haskell java node.js objective-c ocaml perl php python ruby rust smalltalk swift although developed facebook open source project apache software foundation implementation described april 2007 technical paper released facebook hosted apache thrift includes complete stack creating clients servers top part generated code thrift definition file services generate client processor code contrast built-in types created data structures sent result generated code protocol transport layer part runtime library thrift possible define service change protocol transport without recompiling code besides client part thrift includes server infrastructure tie protocols transports together like blocking non-blocking multi-threaded servers underlying i/o part stack implemented differently different languages thrift supports number protocols supported transports thrift also provides number servers stated benefits thrift include thrift written c++ create code number languages create thrift service one write thrift files describe generate code destination language write code start server call client code example description file thrift generate code descriptive information instance java codice_2 simple codice_3 inside codice_4 class
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Internet protocols
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mswlogo mswlogo programming language interpreted based language logo graphical user interface gui front end developed george mills massachusetts institute technology mit core ucblogo brian harvey free open-source software source code available borland c++ mswlogo supports multiple turtle graphics 3d computer graphics allows input ports com lpt also supports windows interface input/output i/o available gui keyboard mouse events trigger interrupts simple gif animations may also produced mswlogo version 6.5 command codice_1 program also used educational software jim muller wrote great logo adventure complete logo manual using mswlogo demonstration language mswlogo evolved fmslogo educational programming environment free open source implementation language logo microsoft windows released gnu general public license gpl mainly developed maintained david costanzo mswlogo version 6.5b supports many functions including
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Programming language topics
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history cp/cms article covers history cp/cms — historical context ibm time-sharing virtual machine operating system built cp/cms development occurred complex political technical milieu historical notes provides supporting quotes citations first-hand observers seminal first-generation time-sharing system ctss first demonstrated mit 1961 production use 1964–74 paved way multics cp/cms time-sharing environments time-sharing concepts first articulated late 50s particularly way meet needs scientific computing time computers primarily used batch processing — jobs submitted punch cards run sequence time-sharing let users interact directly computer calculation simulation results could seen immediately scientific users quickly embraced concept time-sharing pressured computer vendors ibm improved time-sharing capabilities mit researchers spearheaded effort launching project mac intended develop next generation time-sharing technology would ultimately build multics extremely feature-rich time-sharing system would later inspire initial development unix high-profile team leading computer scientists formed specific technical recommendations requirements seeking appropriate hardware platform new system technical problems awesome early time-sharing systems sidestepped problems giving users new modified languages dartmouth basic accessed interpreters restricted execution contexts project mac vision shared unrestricted access general-purpose computing along vendors ibm submitted proposal project mac however ibm proposal well received ibm surprise mit chose ge multics system vendor fallout event led directly cp/cms early 60s ibm struggling define technical direction company identified problem past computer offerings incompatibility many ibm products product lines new product family new generation technology forced customers wrestle entirely new set technical specifications ibm products incorporated wide variety processor designs memory architectures instruction sets input/output strategies etc course unique ibm computer vendors seemed begin new system clean sheet design ibm saw problem opportunity cost software migration increasing barrier hardware sales customers could afford upgrade computers ibm wanted change ibm embarked risky undertaking system/360 product line intended replace ibm diverse earlier offerings including ibm 7000 series canceled ibm 8000 series ibm 1130 series various specialized machines used scientific applications system/360 would span unprecedented range processing power memory size device support cost important based pledge backward compatibility customer could move software new system without modification today world standard interfaces portable systems may seem radical goal time revolutionary system/360 computer model often specific devices programs could used systems buying bigger cpu also meant buying new printers card readers tape drives etc addition customers would rewrite programs run new cpu something customers often balked s/360 ibm wanted offer huge range computer systems sharing single processor architecture instruction set i/o interface operating system customers would able mix match meet current needs could confidently upgrade systems future without need rewrite software applications ibm focus remained traditional customer base large organizations administrative business data processing start system/360 project ibm fully appreciate amount risk involved system/360 ultimately gave ibm total dominance computer industry first nearly put ibm business ibm took one largest ambitious engineering projects history process discovered diseconomies scale mythical man-month extensive literature period fred brooks illustrate pitfalls period system/360 panic project mac asked ibm provide computers extensive time-sharing capabilities direction system/360 project going time-sharing n't seen important ibm main customer base batch processing key moreover time-sharing new ground many concepts involved virtual memory remained unproven example time nobody could explain troubled manchester/ferranti atlas virtual memory n't work later explained due thrashing based cp/cms m44/44x research result ibm system/360 announcement april 1964 include key elements sought time-sharing advocates particularly virtual memory capabilities project mac researchers crushed angered decision system/360 design team met project mac researchers listened objections ibm chose another path february 1964 height events ibm launched cambridge scientific center csc headed norm rassmussen csc serve link mit researchers ibm labs located building project mac ibm fully expected win project mac competition retain perceived lead scientific computing time-sharing one csc first projects submit ibm project mac proposal ibm received intelligence mit leaning toward ge proposal modified 600-series computer virtual memory hardware enhancements would eventually become ge 645 ibm proposed modified s/360 would include virtual memory device called blaauw box – component designed included s/360 mit team rejected ibm proposal modified s/360 seen different rest s/360 line mit want use customized special-purpose computer multics sought hardware would widely available ge prepared make large commitment time-sharing ibm seen obstructive bell laboratories another important ibm customer soon made decision rejected s/360 time-sharing loss project mac devastating csc essentially lost reason existence rasmussen remained committed time-sharing wanted earn back confidence mit researchers made bold decision now-idle csc team would build time-sharing operating system s/360 robert creasy left project mac lead csc team promptly began work become cp-40 first successful virtual machine operating system based fully virtualized hardware ibm loss project mac bell laboratories caused repercussions elsewhere ibm csc soon submitted successful proposal mit lincoln laboratory s/360-67 marking improvement ibm credibility mit committing real time-sharing product rather customized rpq system ibm showing kind commitment mit found ge csc also continued work cp-40 ostensibly provide research input s/360-67 team — also csc team grown skeptical tss project faced aggressive schedule lofty goals since s/360-67 would available csc time team conceived ingenious stopgap measure building virtual-memory s/360 designed set custom hardware microcode changes could implemented s/360-40 providing comparable platform capable supporting cp-40 virtual machine architecture actual cp-40 cms development began mid 1965 even arrival modified s/360-40 first production use cp-40 january 1967 tss project meantime running late struggling problems csc personnel became increasingly convinced cp/cms correct architecture s/360 time-sharing september 1966 csc staff began conversion cp-40 cms run s/360-67 cp-67 significant reimplementation cp-40 varian reports design generalized substantially allow variable number virtual machines larger virtual memories new data structures replaced control blocks describing virtual machines hard-coded part nucleus cp-67 added concept free storage control blocks could allocated dynamically inter-module linkage also reworked code made re-entrant since csc -67 would arrive time csc modified microcode customized s/360-40 simulate s/360-67 – particularly different approach virtual memory csc repeatedly successfully used simulation work around absence hardware waiting modified s/360-40 s/360-67 later first s/370 prototypes seen logical outgrowth virtual machine thinking period early testing cp-67 also done sites s/360-67 hardware available – notably ibm yorktown heights lab mit lincoln laboratory observers cp-67 lincoln labs already frustrated severe tss problems impressed cp-67 insisted ibm provide copy cp/cms according varian demand rocked whole company invested heavily tss however site critical ibm complied varian others speculate chain events could engineered rasmussen subterfuge motivate ibm continued funding csc work counter-strategic cp/cms told several times kill april 1967 – months cp-40 went production – cp/cms already daily use lincoln labs lincoln lab personnel worked closely csc improving cp/cms began enhancing cp cms soon delivered lincoln cambridge people worked together closely exchanged code regular basis beginning tradition code sharing mutual support would continue years around time union carbide another influential ibm customer followed path – deciding run cp/cms send personnel work csc contribute cp/cms development effort cp-40 cp-67 cms essentially research systems time built away ibm mainstream product organizations active involvement outside researchers experimenting important goal constant activity robert creasy cp-40 project leader later wrote design cp/cms small varied software research development group use support… experimenting time-sharing system design ... schedules budgets plans performance goals met.… also expected redo system least got going group meant learning experience efficiency specifically excluded software design goal although always considered know system would practical use ... january 1965 starting work system became apparent presentations outside groups system would controversial tss meantime described varian elegant ambitious system exhibiting serious stability performance problems snatched nest young february 1968 time share 30 eighteen s/360-67 sites attempting run tss conference ibm announced via blue letter tss decommitted — great blow time-sharing community decision would temporarily reversed tss would scrapped 1971 however cp/cms soon began gaining attention viable alternative time s/360-67 software bundled computer hardware purchases see ibm unbundling software services particular ibm operating systems available without additional charge ibm customers cp/cms unusual delivered unsupported type-iii software source code form – meaning cp/cms sites ran unsupported operating system need self-support community support helped lead creation strong s/360-67 cp/cms user communities precursors open source movement summer 1970 cp/cms team begun work system/370 version cp/cms would become vm/370 cp-370 proved vital s/370 project providing usable simulation s/370 s/360-67 hardware – reprise csc earlier hardware simulation strategies approach enabled s/370 development testing s/370 hardware available shortage prototype s/370s causing critical delays mvs project particular remarkable technical feat transformed mvs development award cp-370 developers probably rescued cp project extinction despite aggressive efforts cancel project august 1972 marked end cp/cms ibm system/370 advanced function announcement included new s/370-158 -168 address relocation hardware s/370s four new operating systems dos/vs dos virtual storage os/vs1 os/mft virtual storage os/vs2 os/mvt virtual storage would grow svs mvs vm/370 — re-implemented cp/cms time vm cp/cms development team swelled 110 people including documenters vm/370 real ibm system longer part ibm type-iii library source code distribution continued several releases however see cp/cms free software details 1968 principals small consulting firm connecticut called computer software systems audacious idea leasing ibm system/360-67 run cp/cms reselling computer time audacious ibm would typically lease 50–100k/month systems two-person startup third fourth employees dick orenstein one authors ctss dick bayles csc – primary architect cp-67 key hires cp/cms world included harold feinleib mike field robert jesurum bob jay late november 1968 persuaded ibm accept order small feat secured initial funding css took delivery first s/360-67 began selling time december 1968 css quickly discovered selling every available virtual machine minute published prices could barely take enough revenue pay machine lease whirlwind development program followed ramping cp/cms performance point could resold profitably began fork cp/cms source code evolved independently fifteen years operating system soon renamed vp/css company went public renamed national css although vp/css shared much cp/cms parent vm/370 sibling diverged many important ways business reasons system run profit users frustrated could stop paying time simply hanging phone forces gave high priority factors affecting performance usability customer support vp/css soon became known routinely supporting two three times many interactive users comparable vm systems early ncss enhancements involved areas page migration dispatching file system device support efficient fast-path hypervisor functions accessed via diagnose diag instruction later features included packet-switched network filedef-level pipe interprocess/intermachine communication database integration similar features also appeared vm implementation ultimately ncss development team rivaled size ibm implementing wide array features vp/css platform remained use least mid-80s ncss acquired dun bradstreet 1979 renamed dbcs dun bradstreet computer services increased focus nomad product changed business strategy embrace vm platforms process discontinued support development vp/css probably last non-vm fork cp/cms interactive data corporation idc followed plan similar national css selling time-sharing services based cp/cms platform focus time financial services varian reports idc several s/360-67 systems running cp/cms one ibm first relocating s/370 presumably referring s/370-145 1971 first dat box perhaps systems announced 1972 system/370 advanced function announcement including s/370-158 -168 details citations sought history idc cp/cms time-sharing following notes provide brief quotes primarily pugh varian see references illustrating development context cp/cms direct quotes rather paraphrases provided authors perspectives color interpretations background information citations
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Operating systems
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modula-2 modula-2 computer programming language designed developed 1977 1985 niklaus wirth swiss federal institute technology zurich eth zurich revision pascal serve sole programming language operating system application software personal workstation lilith principal concepts wirth viewed modula-2 successor earlier programming languages pascal modula language design also influenced mesa language new programming possibilities early personal computer xerox alto xerox wirth saw 1976 sabbatical year xerox parc computer magazine byte devoted august 1984 issue language surrounding environment modula-2 general purpose procedural language sufficiently flexible systems programming much broader application particular designed support separate compilation data abstraction straightforward way much syntax based wirth earlier better-known language pascal modula-2 designed broadly similar pascal elements syntactic ambiguities removed important addition module concept direct language support multiprogramming language allows compilation single pass compiler gutknecht wirth four times faster earlier multi-pass compilers example source code hello world program modula-2 module may used encapsulate set related subprograms data structures restrict visibility portions program module design implemented data abstraction feature modula-2 clean way modula-2 programs composed modules made two parts definition module interface portion contains parts subsystem exported visible modules implementation module contains working code internal module language strict scope control particular scope module considered impenetrable wall except standard identifiers object outer world visible inside module unless explicitly imported internal module object visible outside unless explicitly exported suppose module m1 exports objects b c p enumerating identifiers explicit export list objects b c p module m1 become known outside module m1 m1.a m1.b m1.c m1.p exported qualified manner universe assumed module m1 global exporting module name i.e m1 used qualifier followed object name suppose module m2 contains following import declaration means objects exported module m1 universe enclosing program used inside module m2 referenced qualified manner like m1.a m1.b m1.c m1.p example qualified export avoids name clashes instance another module m3 would also export object called p still distinguish two objects since m1.p differs m3.p thanks qualified export matter objects called p inside exporting modules m1 m3 alternative technique available wide use modula-2 programmers suppose module m4 formulated means objects exported module m1 universe used inside module m4 mere references exported identifiers unqualified manner like b c p. example technique unqualifying import allows use variables objects outside exporting module exactly simple i.e unqualified manner inside exporting module walls surrounding modules become irrelevant objects explicitly allowed course unqualifying import usable name clashes export import rules may seem unnecessarily restrictive verbose safeguard objects unwanted access also pleasant side-effect providing automatic cross-referencing definition every identifier program identifier qualified module name definition comes module otherwise occurs unqualified simply search backwards either encounter declaration identifier occurrence import statement names module comes property becomes useful trying understand large programs containing many modules language provides limited single-processor concurrency monitors coroutines explicit transfer control hardware access absolute addresses bit manipulation interrupts uses nominal type system two major dialects modula-2 first pim named book programming modula-2 niklaus wirth three major editions pim second third corrected fourth editions describing slight variants language second major dialect iso standardization effort international organization standardization differences amongst several supersets modula-2 language extensions specific application domains several derivative languages resemble modula-2 closely new languages right different languages different purposes strengths weaknesses many current programming languages adopted features modula-2 pim 2,3,4 defines following 40 reserved words pim 3,4 defines following 29 built-in identifiers cambridge modula-2 cambridge microprocessor systems based subset pim4 language extensions embedded development compiler runs dos generates code m68k based embedded microcontrollers running minos operating system mod51 mandeno granville electronics based iso modula-2 language extensions embedded development following iec1131 industry standard programmable logic controllers plc closely related modula-2 mod51 compiler generates standalone code 80c51 based microcontrollers delco electronics subsidiary gm hughes electronics developed version modula-2 embedded control systems starting 1985 delco named modula-gm first high level language used replace machine language code embedded systems delco engine control units ecus significant delco producing 28,000 ecus per day 1988 gm world largest producer ecus first experimental use modula-gm embedded controller 1985 antilock braking system controller based motorola 68xxx microprocessor 1993 gen-4 ecu used cart championship auto racing teams irl indy racing league teams first production use modula-gm use gm trucks starting 1990 model year vcm vehicle control module used manage gm powertrain vortec engines modula-gm also used ecus gm 90° buick v6 family 3800 series ii used 1997-2005 model year buick park avenue modula-gm compilers associated software management tools sourced delco intermetrics modula-2 selected basis delco high level language many strengths alternative language choices 1986 delco electronics spun gm component divisions form delphi 1997 global sourcing required non-proprietary high-level software language used ecu embedded software developed delphi compiled commercial c compilers serious rumors soviet space program many soviet satellites programmed modula-2 according russian wikipedia article modula-2 satellites russian gps framework glonass programmed modula-2 turbo modula-2 compiler integrated development environment modula-2 programming language running ms-dos developed borland never released instead group including borland cofounder niels jensen acting jensen partners bought unreleased codebase redeveloped released topspeed modula-2 topspeed eventually sold clarion owned softvelocity still offers modula-2 compiler part clarion product line z80 cp/m version turbo modula-2 briefly marketed echelon inc. license borland companion release hitachi hd64180 marketed micromint inc. development tool sb-180 single-board computer
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Programming language topics
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prelude siem intrusion detection system prelude siem security information event management siem tool driving security prelude siem collect centralize information company security offer single point view manage thanks logs flows analyzer prelude siem create alerts intrusions security threats network real time prelude siem provide multiple tools forensic reporting big data smart data identify weak signals advanced persistent threat apt finally prelude siem embeds tools exploitation phase make works easier operators help risk management malicious user software may able evade detection single ids nids hids etc becomes exponentially difficult get around defenses multiple protection mechanisms prelude siem comes large set sensors monitoring different kind events prelude siem permits alert collection wan scale whether scope covers city country continent world prelude siem siem system capable inter-operating systems available market implement natively intrusion detection message exchange format idmef rfc 4765 format start demanded around world way natively idmef compatible opensource ids auditd nepenthes nufw ossec pam samhain sancp snort suricata kismet etc anyone write ids use 3rd party sensors available given prelude siem open apis libraries since 2016 prelude idmef partner program prelude siem also idmef compatible many commercial ids prelude siem provides siem functions three modules alert sem analyze ans archive sim one true siem alternative market plus prelude siem promotes use ietf security standards secef project prelude idmef partner program prelude siem collects normalizes sorts aggregates correlates displays security events regardless types surveillance equipment beyond capacity processing types event logs system logs syslog flat files etc prelude siem natively compatible many ids prelude siem main characteristics following prelude siem oss designed scalable way simply adapt environment free public open-source version gplv2 small infrastructures tests educational purposes open-source version composed following main modules modules base alert module commercial version commercial version also add many functionalities modules scale performances architecture possibilities prelude siem commercial version scalable professionally usable high performance version prelude real-world environments prelude soc fully scaled version mainly soc security operations center usage commercial versions organized like
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Computer security
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ncp engineering ncp engineering styled 'ncp engineering nuremberg-based company produces software remote access industrial internet things security information security ncp products use virtual private network vpn technologies like encryption personal firewalls electronic certificates public key infrastructure pki secure data communication ncp made ipsec vpn client compatible windows 8 windows 10 ios os x linux android operating systems ncp abbreviation network communications products supplement engineering describes company produces software in-house data processing ncp engineering founded nuremberg germany 1986 company produces software secure data communication internet networks via 3g/4g wireless lans core ncp business provisioning secure communication connections stationary mobile end-devices well affiliate branch networks company headquarters 2007 ncp partnered watchguard technologies january 2010 ncp-e established north american affiliate ncp engineering inc february 2010 ncp engineering awarded us patent 8811397 b2 system method data communication user terminal gateway via network node ncp engineering involved esukom project development real-time security solution protects corporate networks using integrated security solutions based unified metadata format since 2010 simu project partner security information event management small smes ncp engineering focused optimizing security corporate networks many years working together 2017 ncp engineering juniper networks intensified collaboration technology partnership
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Computer security
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application permissions application permissions widespread coarse-grained way limit applications access sensitive information example sound recorded microphone valuable resources like battery internet traffic account balance implemented major state art pda operation systems android ios windows web browsers web services providing oauth api list available permissions usually contains accessing android 6 permissions usually revokable though appops mechanism oses usually present vanilla android aftermarket oses usually removed stock oses allowing deprive apps access personal data android ≥6 apps request permissions run time requires app developer collaboration developer free use non-runtime permissions app likely crash permission granted ones granting permission target audience app permissions marked permissions previous versions os like internet access non-revocable even show apps installation fixed xprivacy ios usage permissions regulated using guidelines android ecosystem usage permissions often abused order spy users many applications require much permissions monetize integrating libraries advertising networks showing ads spying users better target webpermissions permission system web browsers web application needs data behind permission must request first user sees window asking make choice choice remembered cleared lately currently following resources controlled cases permissions implemented 'all-or-nothing approach user either grant requested permissions app unable use app even user revoke permission app blackmail user refusing operate example crashing solutions xprivacy instead providing access requested data instead throwing exception crashing app returning disinformation make app operate permission granted also possible use static analysis analyze requested permissions
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Computer security
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knowledge-based authentication knowledge-based authentication commonly referred kba method authentication seeks prove identity someone accessing service financial institution website name suggests kba requires knowledge private information individual prove person providing identity information owner identity two types kba static kba based pre-agreed set shared secrets dynamic kba based questions generated wider base personal information static kba also referred shared secrets shared secret questions commonly used banks financial services companies e-mail providers prove identity customer allowing account access fall-back user forgets password point initial contact customer business using static kba must collect information shared provider customer—most commonly questions corresponding answers data must stored retrieved customer comes back access account weakness static kba demonstrated incident 2008 unauthorised access gained e-mail account former alaska governor sarah palin yahoo account password could reset using shared secret questions including meet spouse along date birth zip code former governor answers easily available online identity verification providers recently introduced secret sounds pictures effort help secure sites information tactics require methods data storage retrieval secret questions dynamic kba high level authentication uses knowledge questions verify individual identity require person provided questions answers beforehand questions compiled public private data marketing data credit reports transaction history initiate process basic identification factors name address date birth must provided consumer checked identity verification service identity verified questions generated real time data records corresponding individual identity provided typically knowledge needed answer questions available person wallet companies call out-of-wallet questions making difficult anyone actual identity owner know answer obtain access secured information generally period time person given respond questions number attempts limited prevent answers researched dynamic kba employed several different industries verify identities customers means fraud prevention compliance adherence type kba based existing relationship consumer gives businesses way higher identity assurance customer identity account origination
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Computer security
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unified access management unified access management uam refers identity management solution used enterprises manage digital identities provide secure access users across multiple devices applications cloud on-premise unified access management solutions provide single platform manage access across diverse set users devices applications whether on-premise cloud unified access management uam evolution identity access management iam systems goal unified access management similar identity access management manage identities individual entities people devices authentication authorization roles privileges within across enterprise systems secure manner bolsters productivity traditional identity access management tools work well addressing specific portions enterprise specific app environments on-premises cloud specific users employees vs. external partners however many businesses must harness multiple iam solutions example may use microsoft active directory web access management tool manage access on-premise applications require identity-as-a-service idaas solutions manage access cloud software service saas apps managing multiple identities access management systems burden information technology departments adds cost requiring maintenance multiple solutions often requires users provisioned de-provisioned multiple systems given iam system may manage access specific devices specific systems fragmented identity management enterprise may able provide true single sign multi-factor authentication effective user lifecycle management slowing digital transformation significant financial impact forrester found 4.47 million annual loss productivity due poor access management per every 10,000 employees hybrid environments complicate access management many organizations able dispense on-premises systems example 2018 47 decision makers surveyed reported majority organization ’ custom applications still run on-premises extensive cost moving legacy systems means organizations likely remain hybrid time uam introduced onelogin uam differs iam providing umbrella solution central cloud directory single source truth identities access cloud directory integrates on-premise identity providers cloud identity providers requests information identity providers updates user lifecycle management work one place cloud directory let uam update appropriate identity providers uam provides functionality needed secure access across users devices typically includes
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Computer security
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urgent computing urgent computing prioritized immediate access supercomputers grids emergency computations severe weather prediction matters immediate concern applications provide decision makers information critical emergencies waste time waiting job queues need access computational resources soon possible
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Distributed computing architecture
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remote backup service remote online managed backup service sometimes marketed cloud backup backup-as-a-service service provides users system backup storage recovery computer files online backup providers companies provide type service end users clients backup services considered form cloud computing online backup systems typically built client software program runs given schedule systems run day usually night computers n't use newer cloud backup services run continuously capture changes user systems nearly real-time online backup system typically collects compresses encrypts transfers data remote backup service provider servers off-site hardware many products market – offering different feature sets service levels types encryption providers type service frequently target specific market segments high-end lan-based backup systems may offer services active directory client remote control open file backups consumer online backup companies frequently beta software offerings and/or free-trial backup services fewer live support options mid-1980s computer industry great state change modems speeds 1200 2400 baud making transfers large amounts data slow 1 mb 72 minutes faster modems secure network protocols development tape backup systems gained popularity period need affordable reliable online backup system becoming clear especially businesses critical data online/remote backup services came existence heyday dot-com boom late 1990s initial years large industry service providers capturing market share understanding importance role online backup providers playing web services arena today service providers online backup services position services using saas software service paas platform service strategy relevance predicted increase exponentially years come personal enterprise data storage needs rise last years also witnessed healthy rise number independent online backup providers enterprise-class cloud backup solution must include on-premises cache mitigate issues due inconsistent internet connectivity hybrid cloud backup works storing data local disk backup captured high speed either backup software d2d2c disk disk cloud appliance encrypts transmits data service provider adds protection local disasters recent backups retained locally speed data recovery operations number cloud storage appliances market used backup target including appliances ctera networks storsimple twinstrata hybrid cloud backup also beneficial enterprise users security concerns storing data locally sending cloud backup users perform necessary encryption operations incl technologies like data encryption additionally applied choose public cloud service provider important compression backup data local backup cache used compress data sending cloud order lower network bandwidth load improve backup speed becomes critical enterprises backup huge databases like oracle ms sql huge files like virtual machine images mail server databases edb files exchange recent improvements cpu availability allow increased use software agents instead hardware appliances enterprise cloud backup software-only approach offer advantages including decreased complexity simple scalability significant cost savings improved data recovery times online backup services usually priced function following things vendors limit number versions file kept system services omit restriction provide unlimited number versions add-on features plug-ins like ability back currently open locked files usually charged extra services provide built remote backup services reduce amount data sent wire backing changed files approach backing means customers total stored data reduced reducing amount data sent also stored drastically reduced transmitting changed data bits binary block level incremental backups solutions transmit changed binary data bits waste bandwidth transmitting file data small amounts change remote backup advantages traditional backup methods remote backup disadvantages traditional backup methods services provide expert backup management services part overall offering services typically include three distinct types backup modes scheduled manual event-based
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Computer security
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stack haskell stack tool build haskell projects manage dependencies uses cabal library together default curated version hackage repository stack competes cabal binary cabal-install created result overall criticism dependency problems however provide package format uses existing codice_1 files complements projects additional codice_2 file
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Operating systems
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inter-asterisk exchange inter-asterisk exchange iax communications protocol native asterisk private branch exchange pbx software supported softswitches pbx systems softphones used transporting voip telephony sessions servers terminal devices original iax protocol deprecated superseded second version commonly called iax2 iax2 protocol published informational non-standards-track rfc 5456 discretion rfc editor february 2010 iax voip protocol used type streaming media including video mainly designed ip voice calls iax uses single user datagram protocol udp data stream endpoints session signaling media payloads thus uses single udp port number typically 4569 feature provides benefits traversing network address translators network boundaries simplifies firewall configuration voip protocols typically use independent streams signaling media session initiation protocol sip h.323 media gateway control protocol mgcp carry media real-time transport protocol rtp iax binary-encoded protocol new extension features must new numeric code allocated historically modeled internal data passing asterisk modules iax supports trunking multiplexing channels single link trunking data multiple sessions merged single stream packets two endpoints reducing ip overhead without creating additional latency advantageous voip transmissions ip headers use large percentage bandwidth iax2 supports native encryption control media streams using aes-128 versions iax protocol created mark spencer much development carried asterisk open-source community primary goals iax minimize bandwidth used media transmissions particular attention drawn control individual voice calls provide native network address translation nat transparency intended easy use behind firewalls
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Internet protocols
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dmalloc dmalloc c memory debugger library written gray watson assist programmers finding variety dynamic memory allocation mistakes replaces parts malloc c standard library provided operating system compiler versions produce information intended help programmer detect problematic code dmalloc find memory leaks off-by-one errors usage invalid addresses library functions calls
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Operating systems
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netcache netcache former web cache software product owned developed netapp 1997 2006 hardware product family incorporating netcache software netcache software started commercial fork harvest object cache developed internet middleware corporation imc consisted former harvest project developers including peter b. danzig professor university southern california late 1996 software named internet middleware object cache referred cached 2 later cached 3 1997 imc acquired netapp software renamed netcache danzig becoming chief architect cto netcache division 2006 netapp sold netcache business technology blue coat systems similar line proxysg appliances became expensive product existing netapp customers hardware netcache appliance included netapp data ontap microkernel write anywhere file layout file system achieving four times throughput software equivalents available time according netapp comparisons starting ontap version 9.5 similar functionality introduced flexcache name november 2005 three hardware models offered former models include
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Internet protocols
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vga-compatible text mode implementation computer monitor text mode vga-compatible hardware quite complex use pc-compatible computers widespread 1980s–1990s particularly dos systems persists today applications even modern desktop computers main features vga text mode colored programmable 16 color palette characters background blinking various shapes cursor block/underline/hidden static/blinking loadable fonts various glyph sizes linux console traditionally uses hardware vga-compatible text modes win32 console environment ability switch screen text mode text window sizes screen character actually represented two bytes aligned 16-bit word accessible cpu single operation lower character byte actual code point current character set higher attribute byte bit field used select various video attributes color blinking character set forth byte-pair scheme among features vga inherited ega cga ultimately mda colors assigned way 4-bit indexed color graphic modes see vga color palette vga modes need mda reverse bright attributes foreground background colors set explicitly vga hardware ability enable underline character attribute bit 0 set however since mda-compatible feature attribute bits used mda must set zero underline shown means bits 3 intensity 7 blink set concurrently bit 0 underline default vga palette setting bit 0 enable underline also change text colour blue means text two colors underlined light blue dark blue default palette despite underline normally visible color modes location underline defaults scanline character glyph rendering invisible underline location set visible scanline default switching mda-compatible monochrome text mode underline appear screen fonts used ega vga monospace raster fonts containing 256 glyphs glyphs font size size changed typically glyphs 8 dots wide 8–16 dots high however height value maximum 32 row glyph coded 8 bit byte high bits left glyph low bits right along several hardware-dependent fonts stored adapter rom text mode offers 8 loadable fonts two active font pointers font font b select two available fonts although usually point font point different fonts attribute bit 3 see acts font selection bit instead foreground color bit real vga hardware overrides bit use color selection many clones emulators color selection remains — meaning one font displayed normal intensity high-intensity error overcome changing palette registers contain two copies 8-color palette modes character box width 9 dots e.g default 80×25 mode however 9th column used spacing characters content changed always blank drawn current background colour exception line graphics enable mode causes code points 0xc0 0xdf inclusive 8th column repeated 9th code points cover box drawing characters must extend way right side glyph box reason placing letter-like characters code points 0xc0–0xdf avoided box drawing characters 0xb0 0xbf extended point right require extending shape cursor restricted rectangle full width character box filled foreground color character cursor current location height position may arbitrary within character box ega many vga clones allowed split-box cursor appearing two rectangles one top character box one bottom setting end cursor start however done original vga cursor completely hidden instead vga standard provide way alter blink rate although common workarounds involve hiding cursor using normal character glyph provide so-called software cursor mouse cursor tui implemented usually thing hardware cursor moving rectangle altered background special glyph text-based interfaces impulse tracker went even greater lengths provide smoother graphic-looking mouse cursor done constantly re-generating character glyphs real-time according cursor on-screen position underlying characters generally two ways access vga text-mode application video bios interface directly accessing video ram i/o ports latter method considerably faster allows quick reading text buffer reason preferred advanced tui programs vga text buffer located physical memory address 0xb8000 since usually used 16-bit x86 processes operating real-mode first half memory segment 0xb800 text buffer data read written bitwise operations applied part text buffer memory scope current mode accessible shown physical addresses used protected mode applications may either part memory mapped address space access via operating system application modern multitasking os control console accesses part system ram instead actual text buffer computers 1980s fast manipulation text buffer hardware generating individual pixels fast could displayed extremely useful fast ui even relatively modern hardware overhead text mode emulation via hardware apa graphics modes program generates individual pixels stores video buffer may noticeable monitor side difference input signal text mode apa mode size text mode signal may timings vesa standard modes registers used adapter side set parameters text mode apa modes text mode output signal essentially graphic modes source text buffer character generator framebuffer apa depending graphics adapter used variety text modes available ibm pc compatible computers listed table vga compatible cards support mda cga ega modes colored modes design text attributes mda modes specific features see — text could emphasized bright underline reverse blinking attributes far common text mode used dos environments initial windows consoles default 80 columns 25 rows 80×25 16 colors mode available practically ibm compatible personal computers two vga text modes 80×43 80×50 exist rarely used 40 column text modes never popular used demonstration purposes old hardware character sizes graphical resolutions extended vesa-compatible super vga text modes manufacturer dependent cards e.g s3 supported custom large text modes like 100×37 even 160×120 like graphic modes graphic adapters 2000s commonly capable set arbitrarily-sized text mode reasonable limits instead choosing parameters list poor software support deters widespread use custom modes linux dos systems named svga cards program called svgatextmode used set better looking text modes ega vga standard ones particularly useful large ≥ 17 monitors normal 80×25 vga text mode 720×400 pixel resolution far lower typical graphics mode would svgatextmode allows setting pixel clock higher refresh rate larger font size cursor size etc. allows better use potential video card monitor non-windows systems use svgatextmode alternative options linux framebuffer obtain sharp text critical lcd monitors 1280×1024 higher resolution none named standard text modes fits matrix size svgatextmode also allows fine tuning video signal timings despite name program supported modes conform svga i.e vesa standards vga text modes hardware-imposed limitations appear restrictive hardware text mode vga compatible video adapters limited use
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Computer architecture
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australian plant census australian plant census apc provides online interface currently accepted published scientific names vascular flora australia one output interfaces national government integrated biodiversity information system ibis – oracle co. relational database management system australian national herbarium australian national botanic gardens australian biological resources study council heads australasian herbaria coordinate system australian plant census interface provides currently accepted scientific names synonyms illegitimate misapplied excluded names well state distribution data item output hyperlinks online interfaces information system including australian plant name index apni australian plant image index apii outputs australian plant census interface provide information native naturalised vascular plant taxa australia including offshore islands excludes taxa known australia cultivation yet naturalised classification plant families based angiosperm phylogeny group iii system 2009
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Databases
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frank rowlett frank byron rowlett may 2 1908 – june 29 1998 american cryptologist rowlett born rose hill lee county virginia attended emory henry college emory virginia 1929 received bachelor degree mathematics chemistry hired william friedman junior cryptanalyst signals intelligence service sis april fools day 1930 shortly followed sis abraham sinkov solomon kullback 1930s lengthy period training rowlett colleagues compiled codes ciphers use u.s. army began solving number foreign notably japanese systems mid-1930s solved first japanese machine encipherment diplomatic communications known americans red 1939–40 rowlett led sis effort solved sophisticated japanese diplomatic machine cipher codenamed purple u.s. asked greatest contribution effort rowlett said one believed could done rowlett also played crucial role protecting american communications world war ii making fundamental innovative contributions design sigaba cipher machine security important factor saving american lives combat 1964 congress awarded rowlett us 100,000 equivalent partial compensation classified cryptologic inventions addition highly developed cryptanalytic skills rowlett good manager rose quickly within organization 1943–45 chief general cryptanalytic branch 1945-1947 chief intelligence division 1949 1952 technical director office operations armed forces security agency predecessor national security agency nsa rowlett differed general ralph j. canine first director nsa personnel movements including acting differences transferred central intelligence agency cia 1952 worked 1958 time returned nsa special assistant director 1965 rowlett became commandant national cryptologic school 1965 rowlett awarded president award distinguished federal civilian service retired federal service 1966 1965 awarded national security medal president lyndon b. johnson work breaking japanese purple cipher rowlett inducted military intelligence hall fame importance protection american communications information systems security organization named highest award frank byron rowlett award frank rowlett died june 29 1998 age 90
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Computer security
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mkdosfs mkdosfs one applications included dosfstools package used create dos file system linux data storage device usually disk partition mkdosfs options device may specify number blocks device allow mkdosfs guess mkdosfs support creating boot-able partitions
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Computer file systems
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ici programming language ici general purpose interpreted computer programming language originally developed tim long late 1980s dynamic typing flexible data types basic syntax flow control constructs operators c. considered broadly similar perl roughly contemporary like perl also tight integration regular expressions ici acronym primitive data types ici include integers reals strings files safe pointers regular expressions aggregate data types arrays sets associative tables sets heterogeneous nested support usual set operations union intersection etc language supports subroutines nested modules variables lexically scoped subroutine module level unlike structured languages ici allows current scope adjusted tcl also allows example ici object-based many object programming features emulated language using data structure inheritance feature called super-structures support application development ici c-like file i/o system interface support well high-level event trigger facility language also modest standard library built-in functions also notable generous license permits use purpose including commercial alteration resale
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Programming language topics
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mini displayport mini displayport minidp mdp miniaturized version displayport audio-visual digital interface announced apple october 2008 2013 new apple macintosh computers port led cinema display however 2016 apple began phasing port replacing new usb-c connector mini displayport also fitted pc motherboards pc notebooks asus microsoft msi lenovo toshiba hp dell manufacturers unlike mini-dvi micro-dvi predecessors mini displayport drive display devices resolutions 2560×1600 wqxga displayport 1.1a implementation 4096×2160 4k displayport 1.2 implementation adapter mini displayport drive display devices vga dvi hdmi interfaces apple offers free license mini displayport reserve right cancel license licensee commence action patent infringement apple apple replaced dvi port macbook macbook air macbook pro imac mac mini mac pro mini displayport use video connector 24-inch cinema display may complicate compatibility
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Computer architecture
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web analytics web analytics measurement collection analysis reporting web data purposes understanding optimizing web usage however web analytics process measuring web traffic used tool business market research assess improve effectiveness website web analytics applications also help companies measure results traditional print broadcast advertising campaigns helps one estimate traffic website changes launch new advertising campaign web analytics provides information number visitors website number page views helps gauge traffic popularity trends useful market research web analytics processes come four essential stages steps another essential function developed analysts optimization websites experiments goal a/b testing identify suggest changes web pages increase maximize effect statistically tested result interest stage impacts impact i.e. drives stage preceding following sometimes data available collection impacts online strategy times online strategy affects data collected least two categories web analytics off-site on-site web analytics historically web analytics used refer on-site visitor measurement however meaning become blurred mainly vendors producing tools span categories many different vendors provide on-site web analytics software services two main technical ways collecting data first traditional method server log file analysis reads logfiles web server records file requests browsers second method page tagging uses javascript embedded webpage make image requests third-party analytics-dedicated server whenever webpage rendered web browser desired mouse click occurs collect data processed produce web traffic reports fundamental goal web analytics collect analyze data related web traffic usage patterns data mainly comes four sources web servers record transactions log file soon realized log files could read program provide data popularity website thus arose web log analysis software early 1990s website statistics consisted primarily counting number client requests hits made web server reasonable method initially since website often consisted single html file however introduction images html websites spanned multiple html files count became less useful first true commercial log analyzer released ipro 1994 two units measure introduced mid-1990s gauge accurately amount human activity web servers page views visits sessions page view defined request made web server page opposed graphic visit defined sequence requests uniquely identified client expired certain amount inactivity usually 30 minutes page views visits still commonly displayed metrics considered rather rudimentary emergence search engine spiders robots late 1990s along web proxies dynamically assigned ip addresses large companies isps made difficult identify unique human visitors website log analyzers responded tracking visits cookies ignoring requests known spiders extensive use web caches also presented problem log file analysis person revisits page second request often retrieved browser cache request received web server means person path site lost caching defeated configuring web server result degraded performance visitor bigger load servers concerns accuracy log file analysis presence caching desire able perform web analytics outsourced service led second data collection method page tagging 'web bugs mid-1990s web counters commonly seen — images included web page showed number times image requested estimate number visits page late 1990s concept evolved include small invisible image instead visible one using javascript pass along image request certain information page visitor information processed remotely web analytics company extensive statistics generated web analytics service also manages process assigning cookie user uniquely identify visit subsequent visits cookie acceptance rates vary significantly websites may affect quality data collected reported collecting website data using third-party data collection server even in-house data collection server requires additional dns lookup user computer determine ip address collection server occasion delays completing successful failed dns lookups may result data collected increasing popularity ajax-based solutions alternative use invisible image implement call back server rendered page case page rendered web browser piece ajax code would call back server pass information client aggregated web analytics company ways flawed browser restrictions servers contacted xmlhttprequest objects also method lead slightly lower reported traffic levels since visitor may stop page loading mid-response ajax call made logfile analysis programs page tagging solutions readily available companies wish perform web analytics cases web analytics company offer approaches question arises method company choose advantages disadvantages approach main advantages log file analysis page tagging follows main advantages page tagging log file analysis follows logfile analysis almost always performed in-house page tagging performed in-house often provided third-party service economic difference two models also consideration company deciding purchase solution cheaper implement depends amount technical expertise within company vendor chosen amount activity seen websites depth type information sought number distinct websites needing statistics regardless vendor solution data collection method employed cost web visitor analysis interpretation also included cost turning raw data actionable information use third party consultants hiring experienced web analyst training suitable in-house person cost-benefit analysis performed example revenue increase cost savings gained analyzing web visitor data companies produce solutions collect data log-files page tagging analyze kinds using hybrid method aim produce accurate statistics either method early hybrid solution produced 1998 rufus evison ip geolocation possible track visitors locations using ip geolocation database api visitors geolocated city region country level ip intelligence internet protocol ip intelligence technology maps internet categorizes ip addresses parameters geographic location country region state city postcode connection type internet service provider isp proxy information first generation ip intelligence referred geotargeting geolocation technology information used businesses online audience segmentation applications online advertising behavioral targeting content localization website localization digital rights management personalization online fraud detection localized search enhanced analytics global traffic management content distribution click analytics special type web analytics gives special attention clicks commonly click analytics focuses on-site analytics editor website uses click analytics determine performance particular site regards users site clicking also click analytics may happen real-time unreal -time depending type information sought typically front-page editors high-traffic news media sites want monitor pages real-time optimize content editors designers types stakeholders may analyze clicks wider time frame help assess performance writers design elements advertisements etc data clicks may gathered least two ways ideally click logged occurs method requires functionality picks relevant information event occurs alternatively one may institute assumption page view result click therefore log simulated click led page view customer lifecycle analytics visitor-centric approach measuring falls umbrella lifecycle marketing page views clicks events api calls access third-party services etc tied individual visitor instead stored separate data points customer lifecycle analytics attempts connect data points marketing funnel offer insights visitor behavior website optimization methods data collection sometimes used packet sniffing collects data sniffing network traffic passing web server outside world packet sniffing involves changes web pages web servers integrating web analytics web server software also possible methods claim provide better real-time data methods globally agreed definitions within web analytics industry bodies trying agree definitions useful definitive time main bodies input area iab interactive advertising bureau jicwebs joint industry committee web standards uk ireland daa digital analytics association formally known waa web analytics association us however many terms used consistent ways one major analytics tool another following list based conventions useful starting point off-site web analytics based open data analysis social media exploration share voice web properties usually used understand market site identifying keywords tagged site either social media websites using http referer webpage owners able trace referrer sites helps bring traffic site hotel problem generally first problem encountered user web analytics problem unique visitors day month add total unique visitors month appears inexperienced user problem whatever analytics software using fact simple property metric definitions way picture situation imagining hotel hotel two rooms room room b table shows hotel two unique users day three days sum totals respect days therefore six period room two unique users sum totals respect rooms therefore four actually three visitors hotel period problem person stays room two nights get counted twice count day counted looking total period software web analytics sum correctly chosen time period thus leading problem user tries compare totals historically vendors page-tagging analytics solutions used third-party cookies sent vendor domain instead domain website browsed third-party cookies handle visitors cross multiple unrelated domains within company site since cookie always handled vendor servers however third-party cookies principle allow tracking individual user across sites different companies allowing analytics vendor collate user activity sites provided personal information activity sites thought anonymous although web analytics companies deny companies companies supplying banner ads done privacy concerns cookies therefore led noticeable minority users block delete third-party cookies 2005 reports showed 28 internet users blocked third-party cookies 22 deleted least month vendors page tagging solutions moved provide least option using first-party cookies cookies assigned client subdomain another problem cookie deletion web analytics depend cookies identify unique visitors statistics dependent persistent cookie hold unique visitor id users delete cookies usually delete first- third-party cookies done interactions site user appear first-time visitor next interaction point without persistent unique visitor id conversions click-stream analysis metrics dependent activities unique visitor time accurate cookies used ip addresses always unique users may shared large groups proxies cases ip address combined user agent order accurately identify visitor cookies available however partially solves problem often users behind proxy server user agent methods uniquely identifying user technically challenging would limit trackable audience would considered suspicious cookies selected option reach lowest common denominator without using technologies regarded spyware may good aware third-party information gathering subject network limitations security applied countries service providers private networks prevent site visit data going third parties methods described methods mentioned like sampling central problem vulnerable manipulation inflation deflation means methods imprecise insecure reasonable model security issue addressed number papers to-date solutions suggested papers remain theoretical possibly due lack interest engineering community financial gain current situation provides owners big websites details consult aforementioned papers
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Web technology
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netgear nsdp nsdp netgear switch discovery protocol management protocol several network device families designed netgear message body records tlv tag-length value structures type field may one following values table list incomplete network devices discovery mac-address device model discovery device firmware update made tftp protocol need send nsdp request turn tftp-server first
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Internet protocols
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abraham sinkov abraham abe sinkov august 22 1907 – january 19 1998 us cryptanalyst early employee u.s. army signals intelligence service held several leadership positions world war ii transitioning new national security agency war became deputy director retiring 1962 taught mathematics arizona state university sinkov son jewish immigrants russia born philadelphia grew brooklyn graduating boys high school took b.s mathematics city college new york coincidence one close friends boys high ccny solomon kullback mr. sinkov taught new york city schools unhappy working conditions anxious use mathematics knowledge practical ways opportunity career change came 1930 sinkov kullback took civil service examination placed high received mysterious letters washington asking knowledge foreign languages sinkov knew french kullback spanish acceptable prospective employer offered positions junior cryptanalysts although neither quite certain cryptanalyst accepted small signals intelligence service sis organization sinkov kullback third fourth employees primary mission compiling codes ciphers use u.s. army secondary task attempt solve selected foreign codes ciphers—this necessarily done intelligence purposes keep cryptanalysts abreast new developments field william friedman put new employees rigorous course study design cryptology bringing high levels skill making breaking codes ciphers friedman also encouraged self-improvement endeavors employees trained summers camp ft. meade earn commissions military reserves sinkov kullback also went receive doctorates mathematics sinkov received phd mathematics 1933 george washington university 1936 sinkov assigned panama canal zone established u.s. army first permanent intercept site outside continental united states sis grew slowly throughout early 1930s however successes japanese diplomatic codes using machine systems 1935 provided u.s. government critical information series crises success practical consequences sis well first time sis began garner respect military superiors military understood small organization could read sensitive messages potential adversary signal corps increased sis budget authorized increased hiring cryptanalysts 1940 even though united states officially combatant u.s. britain initiated exchanges technical material included cautious sharing cryptologic information british stages revealed extent considerable success high-level german systems u.s. equivalent success japanese led unprecedented level cooperation communication intelligence comint two countries war resulting personnel bigger budgets wider range activities organization january 1941 britain battled nazi germany nearly year united states entered second world war captain sinkov selected member delegation united kingdom initial sharing information two countries respective cryptologic programs delegation returned april mixed results report sinkov colleagues shown bletchley park secret headquarters british cryptology exchanged information german japanese systems still unclear much american delegation told british success german enigma machine sinkov later recalled told enigma problem short delegation leave details sketchy nevertheless mission uk success overall helped give us-uk cryptologic relations strong practical foundation japanese attack pearl harbor december 7 1941 japanese also attacked philippine islands general douglas macarthur ordered leave philippines re-establish u.s. army headquarters australia whence counterattacks might launched macarthur recognized need cryptologic support thus 15 april 1942 established central bureau cb cobbling together refugee elements american cryptologists evacuated philippines australian cryptologists allied contingents cb began melbourne moved brisbane july 1942 major sinkov arrived melbourne commander american detachment central bureau director cb paper general spencer b. akin macarthur chief signal officer general akin practice seldom visited organization worked sinkov washington panama confidently left cb operations control sinkov demonstrated strong organizational leadership qualities addition mathematics skills brought group americans australians—representing also different military services countries—into cohesive unit cb quickly became trusted producer signals intelligence sigint macarthur senior commanders sigint enabled consistent success air war japanese allowed macarthur win stunning victories ground campaign new guinea philippines war sinkov rejoined sis renamed army security agency 1949 armed forces security agency afsa —the first centralized cryptologic organization united states—was formed sinkov became chief communications security program remained position afsa made transition national security agency 1954 sinkov became second nsa official attend national war college first louis tordella upon return became deputy director production effectively swapping jobs old colleague frank rowlett sinkov retired nsa 1962 1966 wrote elementary cryptanalysis mathematical approach one first books subject directed high school students available general public abraham sinkov lived retirement arizona two careers 32 years nsa predecessors followed appointment professor mathematics arizona state university colonel sinkov member military intelligence hall fame
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Computer security
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ssl-explorer community edition ssl-explorer community edition open-source ssl vpn product developed 3sp ltd company acquired barracuda networks licensed gnu general public license gpl aimed primarily smaller businesses need remote access internal network resources product designed installed standalone server allows user connect remotely internal corporate resources intranet websites network file shares ‘ fat client ’ applications data via regular web browser gives end users access applications would use every day work simple web browser without necessity installing dedicated vpn client software product first released sourceforge.net website august 2004 since 275,000 downloads main product distribution december 2007 versions core community edition product licensed gpl commercial enterprise edition product built upon community edition additional functionality licensed separately commercial license fork last gpl release created named adito later renamed openvpn als around march 2008 3sp ltd announced discontinued development community edition ssl-explorer known install function following operating systems product previously licensed gpl source code still available via sourceforge.net however future updates source code pre-built binaries forthcoming 3sp ltd. november 18 2008 3sp ltd. part barracuda networks technology behind ssl-explorer incorporated barracuda ssl vpn ssl-explorer application written java contains database web server used serve secure web pages order access back-end network resources product ideally installed upon standalone server may installed service run background processes desired product acts web-based proxy mediates requests resources external users also providing means authenticating users identities querying number user databases including microsoft active directory access rights enforced principle role based access control secondary access control measures ntfs filesystem permissions also affect resources user may access resources e.g remote desktop access require use port forwarding operate successfully purpose lightweight java applet known 'ssl-explorer agent downloaded launched client browser applet intercepts tcp/ip requests certain configurable ports forwards ssl-explorer server turn routes appropriate endpoint network using combination various techniques web proxying port forwarding corporate applications continue function unimpeded data tunneled transparently end point client via ssl-explorer using https protocol network resources may externalized ssl-explorer include following actual vpn server may placed inside either dmz within trusted network incoming connections port 443 forwarded directly ssl-explorer firewall rules one main advantages associated ssl vpn products lies fact correctly set technically possible close firewall ports apart https/ssl port 443 often lumped together similar solutions ssl-explorer conceptually different openvpn provides controlled authenticated access services applications within network rather full unchallenged network access ssl-explorer ssl vpn products whole beneficial many people number distinct groups benefit greatly usage community edition ssl-explorer provided number security features features one-time-password support hardware token authentication offered via commercial implementation barracuda ssl vpn february 2007 3sp ltd conducted performance benchmarking ssl-explorer solution using test bed platform three systems using different specifications hardware benchmarking conducted assumption minimum 256 kbit/s data throughput rate would realistic value place upon responsive vpn tunnel use remote desktop access bea jrockit jre used tests microsoft windows linux systems results obtained indicated ssl-explorer known operate successfully using ncipher nfast ln1200 ssl accelerator card ssl-explorer built using number open source software components frameworks notable projects summarized june 2007 secunia published advisory stating versions ssl-explorer prior 0.2.13 vulnerable cross-site scripting attacks http header injection attacks 3sp ltd fixed vulnerability later versions product advised users upgrade servers currently us-cert advisory notice unresolved potential security flaw affecting whole class url-rewriting clientless ssl vpn products including versions ssl-explorer derivatives many similar utilities see
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Computer security
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plants world online plants world online online database published royal botanic gardens kew launched march 2017 ultimate aim enable users access information world known seed-bearing plants 2020 initial focus tropical african floras particularly flora zambesiaca flora west tropical africa flora tropical east africa
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Databases
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jetbrains mps jetbrains mps metaprogramming system developed jetbrains mps tool design domain-specific languages dsl uses projectional editing allows users overcome limits language parsers build dsl editors ones tables diagrams. br implements language-oriented programming mps environment language definition language workbench integrated development environment ide languages developers different domains benefit domain specific language extensions general purpose programming languages example java developers working financial applications might benefit built-in support monetary values unfortunately traditional text based languages subject text ambiguity problems makes extensions problematic mps supports composable language definitions means languages extended embedded extensions used work program mps example java extended better syntax collections extended better syntax dates extensions work well together mps solves grammar ambiguity issues working abstract syntax tree directly order edit tree text-like projectional editor used mps provides reusable language infrastructure configured language definition languages mps also provides many ide services automatically editor code completion find usages etc mbeddr embedded development system based mps languages tailored embedded development formal methods october 2009 jetbrains released youtrack bug tracking system first commercial software product developed mps april 2010 realaxy actionscript editor beta released first commercial ide based mps platform peopl tool software product line engineering realised mps mps source code released apache license
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Programming language topics
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mach 3 1987 video game mach 3 1987 3d shooter video game loriciels amiga amstrad cpc atari st msx thomson to7 zx spectrum ibm pc pc version uses cga 320x200 video mode player controls spacecraft shoots various enemy crafts avoiding mines obstacles intro screen sampled phrase spoken get ready mach 3
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Computer architecture
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slackpkg slackpkg software tool installing upgrading packages automatically network internet slackware slackpkg included main tree slackware 12.2 previously included extras/ since slackware 9.1 licensed gnu general public license gpl slackpkg automated package management tool written slackware shell script like swaret designed make slackware system administrator job easier allowing routine package management tasks accomplished single command slackpkg replace slackware package management tools installpkg upgradepkg rather uses features slackpkg include automated package installation upgrading searching many features package deinstallation performed directly using slackware package tools though incorporation slackpkg provides consistent user interface slackpkg resolve dependencies packages like rpm fedora opensuse third-party applications slapt-get automated package relation management
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Operating systems
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common log file system common log file system clfs general-purpose logging subsystem accessible kernel-mode well user-mode applications building high-performance transaction logs introduced windows server 2003 r2 included later windows operating systems clfs used data logging well event logging clfs used txf txr store transactional state changes commit transaction binary log file created clfs viewed integrated windows tool job clfs like transactional logging system record series steps required action either played back accurately future commit transaction secondary storage undone required clfs first marshals logs records in-memory buffers writes log-files secondary storage stable media clfs terminology permanent persistence data flushed stable media controlled built-in policies clfs client application override force flush clfs allows customizable log formats expansion truncation logs according defined policies well simultaneous use multiple client applications clfs able store log files anywhere file system clfs defines device driver interface ddi via physical storage system specific drivers plug clfs api clfs driver implements aries recovery algorithm algorithms supported using custom drivers clfs supports dedicated logs well multiplexed logs dedicated log contains single stream log records whereas multiplexed log contain multiple streams stream different application even though multiplexed log multiple streams logs flushed streams sequentially single batch clfs allocate space set log records ahead-of-time logs actually generated make sure operation fail due lack storage space log record clfs stream first placed log i/o block buffer system memory periodically blocks flushed stable storage devices storage device log contains set containers allocated contiguously containing multiple log i/o blocks new log records appended present set record identified log sequence number lsn increasing 32-bit sequence number lsn metadata stored record header lsn encodes identifier container offset record identifier record information used access log record subsequently however container identifiers logical identifiers must mapped physical containers mapping done clfs
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Operating systems
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open mashup alliance open mashup alliance oma non-profit consortium promotes adoption mashup solutions enterprise evolution enterprise mashup standards like emml enterprise mashup usage expected grow tenfold next five years initial members oma include large technology companies adobe systems hewlett-packard intel major technology users bank america capgemini according information technology industry analyst dion hinchcliffe ultimately oma creates standardized approach enterprise mashups creates open vibrant market competing runtimes mashups array important aftermarket services development/testing tools management administration appliances governance frameworks education professional services initial focus oma developing emml declarative mashup domain-specific language dsl aimed creating enterprise mashups emml language provides comprehensive set high-level mashup-domain vocabulary consume mash variety web data-sources diverse ways emml provides uniform syntax invoke heterogeneous service styles rest wsdl rss/atom rdbms pojo emml also provides ability mix match diverse data-formats xml json jdbc javaobjects primitive types oma web site provides emml specification emml schema reference runtime implementation capable running emml scripts sample emml mashup scripts technical documentation oma developing emml creative commons attribution derivatives license license means emml users allowed copy distribute emml however emml altered users ownership emml oma must made clear redistribution eventual objective oma submit emml specification oma specifications recognized industry standards body
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Web technology
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network admission control network admission control nac refers cisco version network access control restricts access network based identity security posture network device switch router wireless access point dhcp server etc configured nac force user machine authentication prior granting access network addition guest access granted quarantine area remediation problems may caused authentication failure enforced inline custom network device changes existing switch router restricted dhcp class typical non-free wifi connection form nac user must present sort credentials credit card granted access network initial phase cisco network admission control nac functionality enables cisco routers enforce access privileges endpoint attempts connect network access decision basis information endpoint device current antivirus state antivirus state includes information version antivirus software virus definitions version scan engine network admission control systems allow noncompliant devices denied access placed quarantined area given restricted access computing resources thus keeping insecure nodes infecting network key component cisco network admission control program cisco trust agent resides endpoint system communicates cisco routers network cisco trust agent collects security state information antivirus software used communicates information cisco routers information relayed cisco secure access control server acs access control decisions made acs directs cisco router perform enforcement endpoint cisco product marked end life since november 30 2011 cisco terminology product longer developed supported besides user authentication authorization nac based upon compliance checking posture assessment evaluation system security based applications settings particular system using might include windows registry settings presence security agents anti-virus personal firewall nac products differ checking mechanisms nac vendors require 802.1x supplicant client agent installed including hexis netbeat nac trustwave enterasys offer agent-less posture checking designed handle bring device byod scenario agent-less approach works heterogenously across almost network environments network device types
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Computer security
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dreamshell dreamshell unix-like operating system designed sega dreamcast video game console based kallistios libraries originally command line interface ability run third-party applications later versions dreamshell gained gui xml-module support applications written lua-scripts ability enhance functionality using functions klf-modules analogous dll kallisti os fixed modules mp3 ogg loaded console commands appear play formats well support implemented file manager internal external commands added facilitate ds kernel first application appeared dreamshell version 4.0 allows install operating system directly dreamcast bios lets change console regional setting video output format pal ntsc without flashing bios application relies consoles modified motherboard
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Operating systems
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crimeware crimeware class malware designed specifically automate cybercrime crimeware distinct spyware adware designed perpetrate identity theft social engineering technical stealth order access computer user financial retail accounts purpose taking funds accounts completing unauthorized transactions enrich cyberthief alternatively crimeware may steal confidential sensitive corporate information crimeware represents growing problem network security many malicious code threats seek pilfer confidential information term crimeware coined david jevans february 2005 anti-phishing working group response fdic article putting end account-hijacking identity theft published december 14 2004 criminals use variety techniques steal confidential data crimeware including following methods crimeware threats installed victims computers multiple delivery vectors including crimeware significant economic impact due loss sensitive proprietary information associated financial losses one survey estimates 2005 organizations lost excess 30 million due theft proprietary information theft financial confidential information corporate networks often places organizations violation government industry-imposed regulatory requirements attempt ensure financial personal confidential us laws regulations include
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Computer security
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java apis bluetooth java apis bluetooth wireless technology jabwt j2me specification apis allows java midlets running embedded devices mobile phones use bluetooth short-range wireless communication jabwt developed jsr-82 java community process jsr 82 implementations java 2 platform standard edition j2se also available original java specification request jsr-82 submitted motorola sun microsystems approved executive committee j2me september 2000 jsr-82 provided first standardized java api bluetooth protocols allowing developers write applications using bluetooth work devices conforming specification first version jsr-82 released march 2002 recent update jsr-82 maintenance draft review 4 released march 2010 specification reference implementation technology compatibility kit tck maintained motorola open source jabwt provides support discovery nearby bluetooth devices java applications use api scan discoverable devices identify services provided discovered devices search devices device frequently contacts jabwt provides object exchange api transfer data objects devices example two devices conforming obex protocol could exchange virtual business cards calendar appointments jabwt allows management local device ’ state jabwt applications able access information host device bluetooth address mark host device discoverable bluetooth devices register provide services jabwt supports connections different levels security applications using apis pass parameters connector.open method indicating level security required establish connection another device hundreds mobile devices different manufacturers comply jsr-82 specification google maintains list devices conform jsr-82 specification several open-source implementations jsr-82 specification available
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Programming language topics
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sdes sdes session description protocol security descriptions media streams way negotiate key secure real-time transport protocol proposed standardization ietf july 2006 see rfc 4568 keys transported sdp attachment sip message means sip transport layer must make sure no-one else see attachment done using tls transport layer methods like s/mime using tls assumes next hop sip proxy chain trusted take care security requirements request main advantage method extremely simple key exchange method picked several vendors already even though vendors use secure mechanism transport key helps get critical mass implementation make method de facto standard illustrate principle example phone sends call proxy using sips scheme indicates call must made secure key base-64 encoded sdp attachment phone receives answer proxy two-way secure call common problem secure media key exchange might finished first media packet arrives order avoid initial clicks packets must dropped usually short period time 100 ms major problem sdes method address end-to-end media encryption example user talking user b via proxy p sdes allows negotiation keys p b p b end-to-end media security must first establish trust relationship side use trusted intermediate call setup delay significantly increase makes applications like push-to-talk difficult peer-to-peer might difficult identify side example operator might implement b2bua architecture play role side still n't end-to-end security newer modern protocols like zrtp offer end-to-end encryption sip/rtp calls
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Internet protocols
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moose file system moose file system moosefs open-source posix-compliant distributed file system developed core technology moosefs aims fault-tolerant highly available highly performing scalable general-purpose network distributed file system data centers initially proprietary software released public open source may 30 2008 currently two editions moosefs available moosefs follows similar design principles fossil file system google file system lustre ceph file system comprises three components achieve high reliability performance moosefs offers following features similarly cluster-based file systems moosefs uses commodity hardware running posix compliant operating system tcp/ip used interconnect
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Computer file systems
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central equipment identity register central equipment identity register database imei numbers blacklisted handsets device esn imei number listed ceir supposed work member service providers networks paying members may access database number features added ceir like providing statistics number handset types growth/decline per network reported daily weekly monthly yearly base also see msisdn imsi used imei search imei used imsi common usage ceir stolen mobile devices user reports operator theft mobile devices imei number entered ceir supposedly making device unusable network although always work key reason sometimes work many operators many countries contribute imeis ceir also unique profile determines operators blocks included ceir updates received operator uk networks example receive block records originated non-uk networks annual fees required access ceir access tightly regulated contributing operators decide handsets block networks many network operators simply participate blocking users means losing revenue operators often trade business ethics revenue one operator country block use stolen handsets revenue flows operator instead ethical ones currently central equipment identity register frequently called imei db database system means central system network operators eir share individual blacklists one another service denied particular devices appear blacklist idea network operators compile one global blacklist imei db however agreement single ceir equipment identity register reduces threats theft mobile devices enabling individual operators prevent use stolen mobile devices networks improves users security switching stolen mobile devices making useless bricked mobile devices thieves thus less likely stolen first place number mobile devices messaging users continue grow become target fraudulent criminal activities mobile messaging application infrastructure companies nokia mavenir comviva primal technologies svyazcom tekelec examples providers equipment identity worldwide mobile operators like vodafone airwide mts svyazcom 4gtss cegetel tekelec deploy lists ceirs tra mandatory rule use ceir operator network prevent handset theft cloning dual sim cards imei:358251074242576
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Computer security
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protection profile protection profile pp document used part certification process according iso/iec 15408 common criteria cc generic form security target st typically created user user community provides implementation independent specification information assurance security requirements pp combination threats security objectives assumptions security functional requirements sfrs security assurance requirements sars rationales pp specifies generic security evaluation criteria substantiate vendors claims given family information system products among others typically specifies evaluation assurance level eal number 1 7 indicating depth rigor security evaluation usually form supporting documentation testing product meets security requirements specified pp national institute standards technology nist national security agency nsa agreed cooperate development validated u.s. government pps pp states security problem rigorously given collection system products known target evaluation toe specify security requirements address problem without dictating requirements implemented pp may inherit requirements one pps order get product evaluated certified according cc product vendor define security target st may comply one pps way pp may serve template product st although eal easiest laymen compare simplicity deceptive number rather meaningless without understanding security implications pp st used evaluation technically comparing evaluated products requires assessing eal functional requirements unfortunately interpreting security implications pp intended application requires strong security expertise evaluating product one thing deciding product cc evaluation adequate particular application quite another obvious trusted agency possesses depth security expertise needed evaluate systems applicability common criteria evaluated products problem applying evaluations new problem addressed decades ago massive research project defined software features could protect information evaluated strength mapped security features needed specific operating environment risks results documented rainbow series rather separating eal functional requirements orange book followed less advanced approach defining functional protection capabilities appropriate assurance requirements single category seven categories defined way yellow book defined matrix security environments assessed risk established precisely security environment valid orange book categories approach produced unambiguous layman cookbook determine whether product usable particular application loss application technology seems unintended consequence superseding orange book common criteria
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Computer security
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logo programming language logo educational programming language designed 1967 wally feurzeig seymour papert cynthia solomon logo acronym name coined feurzeig bolt beranek newman derives greek logos meaning word thought general-purpose language logo widely known use turtle graphics commands movement drawing produced line vector graphics either screen small robot termed turtle language conceived teach concepts programming related lisp later enable papert called body-syntonic reasoning students could understand predict reason turtle motion imagining would turtle substantial differences among many dialects logo situation confused regular appearance turtle graphics programs named logo logo multi-paradigm adaptation dialect lisp functional programming language standard logo ucblogo best facilities handling lists files i/o recursion scripts used teach computer science concepts uc berkeley lecturer brian harvey computer science logo style trilogy logo usually interpreted language although developed compiled logo dialects lhogho liogo logo case-sensitive retains case used formatting logo created 1967 bolt beranek newman bbn cambridge massachusetts research firm wally feurzeig cynthia solomon seymour papert intellectual roots artificial intelligence mathematical logic developmental psychology first four years logo research development teaching work done bbn first implementation logo called ghost written lisp pdp-1 goal create mathematical land children could play words sentences modeled lisp design goals logo included accessible power informative error messages use virtual turtles allowed immediate visual feedback debugging graphic programming first working logo turtle robot created 1969 display turtle preceded physical floor turtle modern logo changed much basic concepts first turtle first turtle tethered floor roamer radio-controlled wireless bbn paul wexelblat developed turtle named irving touch sensors could move forwards backwards rotate ding bell earliest year-long school users logo 1968-69 muzzey jr high lexington virtual physical turtles first used fifth-graders bridge school lexington 1970-71 logo most-known feature turtle derived originally robot name on-screen cursor showed output commands movement small retractable pen together producing line graphics traditionally displayed either triangle turtle icon though represented icon turtle graphics added logo language seymour papert late 1960s support papert version turtle robot simple robot controlled user workstation designed carry drawing functions assigned using small retractable pen set attached robot body practical matter use turtle geometry instead traditional model mimics actual movement logic turtle robot turtle moves commands relative position left 90 means spin left 90 degrees logo implementations particularly allow use concurrency multiple turtles support collision detection allow user redefine appearance turtle cursor essentially allowing logo turtles function sprites multiple turtles supported mswlogo well 3d graphics input com ports lpt ports also allowed mswlogo windows gui interrupts triggered via keyboard mouse events simple gif animations may also produced mswlogo version 6.5 gifsave command turtle geometry also sometimes used environments logo alternative strictly coordinate-addressed graphics system instance idea turtle graphics also useful lindenmayer system generating fractals modern derivatives logo allow thousands independently moving turtles two popular implementations massachusetts institute technology starlogo northwestern university center connected learning ccl netlogo allow exploring emergent phenomena come many experiments social studies biology physics areas netlogo widely used agent-based simulation biological social sciences although one agreed-upon standard broad consensus core aspects language march 2009 197 implementations dialects logo strengths 197 longer wide use many still active development commercial logos still widely used schools include microworlds logo imagine logo logo primary influence smalltalk programming language also main influence etoys educational programming environment language essentially logo written squeak variant smalltalk logo influenced procedure/method model agentsheets agentcubes program agents similar notion turtle logo logo provided underlying language boxer boxer developed university california berkeley mit based literacy model making easier use nontechnical people kturtle variation logo implemented qt kde environment loosely based logo another result logo influence kojo variant scala scratch educational programming language runs squeak variant smalltalk inspired logo 2015 cubetto education robotics system children 3 years older developed crowd-source funding cubetto influenced logo montessori cubetto features small cubic turtle turns 90 degrees cubetto described update button-box mit logo system tortis
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Programming language topics
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digital omnivore digital omnivore descriptive term meant capture indiscriminate seamless modalities consumers use access world wide web cultural meme reflects popularization smartphones introduction tablets web-enabled devices allow consumers access media content several touch-points course daily digital lives mobile web users increasingly mobile devices cross-platform multimedia consumption continue re-shape digital landscape terms type media content consume consume according new 2011 survey comscore smartphones tablets driving nearly 7 digital traffic united states two-thirds growth attributed smartphones alone today half u.s. mobile population uses mobile media 19 past year 116 million people growth expected increase 36.1 americans age 13 smartphone digital omnivores global phenomenon driving 5 non-computer device internet traffic august 2011 singapore leads way 7.2 u.s united kingdom score 6.8 australia canada complete top five global markets 5.3 4.4 respectively looking deeper 6.8 non-pc web-browsing done u.s. find 64.4 comes mobile phones 28.1 tablets 7.5 devices game consoles e-readers means u.s. 4 overall web browsing comes smartphones 1.6 tablets small figures point way people beginning toggle devices across various day-parts analysis way consumers u.s. viewed news content different devices throughout day demonstrates influence devices way people consume content typical weekend morning digital omnivores access news using tablet favor computer working day return tablet use evening peaking hours 9pm midnight mobile phones used web-browsing throughout day users away personal computer increased wi-fi availability mobile broadband adoption changing way people going online today august 2011 third 37.2 u.s. digital traffic coming mobile phones occurred via wi-fi connection tablets traditionally required wi-fi connection access internet increasingly driving traffic using mobile broadband access tablets yet widely adopted already contribute nearly 2 web browsing traffic united states traffic driven almost exclusively ipad accounted 97 tablet traffic second half 2011 period ipads also began account higher share internet traffic iphones 46.8 vs. 42.6 ios device traffic u.s. tablet users largely display demographic characteristics early technology adopters younger males 49.5 age 34 average incomes 45.9 belong households earning 100,000 year point time half tablet users report used tablet least previous month activities social networking online shopping consuming news viewing videos entertainment current trend content providers optimizing sites tablets creating tablet-specific apps continues likely tablet owners interact devices even messaging set connected consumers move effortlessly online terrestrial lives may seem chaotic complex difficult navigate actually presenting opportunities never thought possible media execution buying quickly becoming new creativity levers marketers smartphone tablet connected device represents unique canvas media engagement brands strategically manage communication strategy across complementary messaging matrix best positioned create long term loyalty high engagement audiences consumers utilizing full-spectrum digital devices cultural communicators must understand patterns order develop incremental unduplicated reach across entire digital ecosystem
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Distributed computing architecture
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x86 assembly language x86 assembly language family backward-compatible assembly languages provide level compatibility way back intel 8008 introduced april 1972. x86 assembly languages used produce object code x86 class processors like assembly languages uses short mnemonics represent fundamental instructions cpu computer understand follow compilers sometimes produce assembly code intermediate step translating high level program machine code regarded programming language assembly coding machine-specific low level assembly languages typically used detailed time critical applications small real-time embedded systems operating system kernels device drivers x86 assembly instruction represented mnemonic often combined one operands translates one bytes called opcode nop instruction translates 0x90 instance hlt instruction translates 0xf4 potential opcodes documented mnemonic different processors may interpret differently making program using behave inconsistently even generate exception processors opcodes often turn code writing competitions way make code smaller faster elegant show author prowess x86 assembly language two main syntax branches intel syntax originally used documentation x86 platform syntax intel syntax dominant ms-dos windows world syntax dominant unix world since unix created bell labs summary main differences intel syntax syntax many x86 assemblers use intel syntax including nasm fasm masm tasm yasm gas supported syntaxes since version 2.10 via .intel_syntax directive x86 processors collection registers available used stores binary data collectively data address registers called general registers register special purpose addition along general registers additionally ip register points memory offset next instruction code segment points first byte instruction ip register accessed programmer directly x86 registers used using mov instructions example intel syntax mov ax 1234h copies value 1234hex 4660d register ax mov bx ax copies value ax register bx register x86 architecture real virtual 8086 mode uses process known segmentation address memory flat memory model used many environments segmentation involves composing memory address two parts segment offset segment points beginning 64 kb group addresses offset determines far beginning address desired address segmented addressing two registers required complete memory address one hold segment hold offset order translate back flat address segment value shifted four bits left equivalent multiplication 2 16 added offset form full address allows breaking 64k barrier clever choice addresses though makes programming considerably complex real mode/protected example ds contains hexadecimal number 0xdead dx contains number 0xcafe would together point memory address 0xdead 0x10 0xcafe 0xeb5ce therefore cpu address 1,048,576 bytes 1 mb real mode combining segment offset values find 20-bit address original ibm pc restricted programs 640 kb expanded memory specification used implement bank switching scheme fell use later operating systems windows used larger address ranges newer processors implemented virtual memory schemes protected mode starting intel 80286 utilized os/2 several shortcomings inability access bios inability switch back real mode without resetting processor prevented widespread usage 80286 also still limited addressing memory 16-bit segments meaning 2 bytes 64 kilobytes could accessed time access extended functionality 80286 operating system would set processor protected mode enabling 24-bit addressing thus 2 bytes memory 16 megabytes protected mode segment selector broken three parts 13-bit index table indicator bit determines whether entry gdt ldt 2-bit requested privilege level see x86 memory segmentation referring address segment offset notation segment offset used example flat address 0xeb5ce written 0xdead:0xcafe segment offset register pair ds dx special combinations segment registers general registers point important addresses intel 80386 featured three operating modes real mode protected mode virtual mode protected mode debuted 80286 extended allow 80386 address 4 gb memory new virtual 8086 mode vm86 made possible run one real mode programs protected environment largely emulated real mode though programs compatible typically result memory addressing tricks using unspecified op-codes 32-bit flat memory model 80386 extended protected mode may important feature change x86 processor family amd released x86-64 2003 helped drive large scale adoption windows 3.1 relied protected mode since windows could run many applications including dos applications using virtual memory simple multitasking x86 processors support five modes operation x86 code real mode protected mode long mode virtual 86 mode system management mode instructions available others 16-bit subset instructions available 16-bit x86 processors 8086 8088 80186 80188 80286 instructions available real mode x86 processors 16-bit protected mode 80286 onwards additional instructions relating protected mode available 80386 later 32-bit instructions including later extensions also available modes including real mode cpus v86 mode 32-bit protected mode added additional instructions provided modes manage features smm special instructions available intel i386sl i486 later cpus finally long mode amd opteron onwards 64-bit instructions registers also available instruction set similar mode memory addressing word size vary requiring different programming strategies modes x86 code executed processor runs real mode immediately power operating system kernel program must explicitly switch another mode wishes run anything real mode switching modes accomplished modifying certain bits processor control registers preparation additional setup may required switch general features modern x86 instruction set x86 architecture hardware support execution stack mechanism instructions codice_8 codice_9 codice_10 codice_11 used properly set stack pass parameters allocate space local data save restore call-return points codice_11 size instruction useful implementing space efficient fast calling conventions callee responsible reclaiming stack space occupied parameters setting stack frame hold local data recursive procedure several choices high level codice_13 instruction introduced 80386 takes procedure-nesting-depth argument well local size argument may faster explicit manipulation registers codice_14 codice_15 codice_16 whether faster slower depends particular x86-processor implementation well calling convention used compiler programmer particular program code x86 code intended run x86-processors several manufacturers different technological generations processors implies highly varying microarchitectures microcode solutions well varying gate- transistor-level design choices full range addressing modes including immediate base+offset even instructions codice_8 codice_9 makes direct usage stack integer floating point address data simple well keeping abi specifications mechanisms relatively simple compared risc architectures require explicit call stack details x86 assembly standard mathematical operations codice_19 codice_20 codice_21 codice_22 logical operators codice_23 codice_24 codice_25 codice_26 bitshift arithmetic logical codice_27/codice_28 codice_29/codice_30 rotate without carry codice_31/codice_32 codice_33/codice_34 complement bcd arithmetic instructions codice_35 codice_36 codice_37 others x86 assembly language includes instructions stack-based floating-point unit fpu fpu optional separate coprocessor 8086 80386 on-chip option 80486 series standard feature every intel x86 cpu since 80486 starting pentium fpu instructions include addition subtraction negation multiplication division remainder square roots integer truncation fraction truncation scale power two operations also include conversion instructions load store value memory following formats binary-coded decimal 32-bit integer 64-bit integer 32-bit floating-point 64-bit floating-point 80-bit floating-point upon loading value converted currently used floating-point mode x86 also includes number transcendental functions including sine cosine tangent arctangent exponentiation base 2 logarithms bases 2 10 e stack register stack register format instructions usually codice_38 codice_39 codice_40 equivalent codice_41 codice_42 one 8 stack registers codice_41 codice_44 ... codice_45 like integers first operand first source operand destination operand codice_46 codice_47 singled first swapping source operands performing subtraction division addition subtraction multiplication division store comparison instructions include instruction modes pop top stack operation complete example codice_48 performs calculation codice_49 removes codice_41 top stack thus making result codice_44 top stack codice_41 modern x86 cpus contain simd instructions largely perform operation parallel many values encoded wide simd register various instruction technologies support different operations different register sets taken complete whole mmx sse4.2 include general computations integer floating point arithmetic addition subtraction multiplication shift minimization maximization comparison division square root example codice_53 performs 4 parallel 16-bit indicated codice_54 integer adds indicated codice_55 codice_56 values codice_57 stores result codice_56 streaming simd extensions sse also includes floating point mode first value registers actually modified expanded sse2 unusual instructions added including sum absolute differences used motion estimation video compression done mpeg 16-bit multiply accumulation instruction useful software-based alpha-blending digital filtering sse since sse3 3dnow extensions include addition subtraction instructions treating paired floating point values like complex numbers instruction sets also include numerous fixed sub-word instructions shuffling inserting extracting values around within registers addition instructions moving data integer registers xmm used sse /fpu used mmx registers x86 processor also includes complex addressing modes addressing memory immediate offset register register offset scaled register without offset register optional offset another scaled register example one encode codice_59 single instruction loads 32 bits data address computed codice_60 offset codice_61 selector stores codice_62 register general x86 processors load use memory matched size register operating simd instructions also include half-load instructions x86 instruction set includes string load store move scan compare instructions codice_63 codice_64 codice_65 codice_66 codice_67 perform operation specified size codice_68 8-bit byte codice_54 16-bit word codice_70 32-bit double word increments/decrements depending df direction flag implicit address register codice_71 codice_63 codice_73 codice_64 codice_66 codice_65 codice_67 load store scan operations implicit target/source/comparison register codice_78 codice_79 codice_62 register depending size implicit segment registers used codice_61 codice_71 codice_83 codice_73 codice_85 codice_86 register used decrementing counter operation stops counter reaches zero scans comparisons inequality detected stack implemented implicitly decrementing push incrementing pop stack pointer 16-bit mode implicit stack pointer addressed ss sp 32-bit mode ss esp 64-bit mode rsp stack pointer actually points last value stored assumption size match operating mode processor i.e. 16 32 64 bits match default width codice_8/codice_9/codice_10/codice_11 instructions also included instructions codice_13 codice_92 reserve remove data top stack setting stack frame pointer codice_93/codice_1/codice_2 however direct setting addition subtraction codice_96/codice_97/codice_98 register also supported codice_13/codice_92 instructions generally unnecessary code beginning function ... functionally equivalent instructions manipulating stack include codice_101/codice_102 storing retrieving e flags register codice_103/codice_104 instructions store retrieve entire integer register state stack values simd load store assumed packed adjacent positions simd register align sequential little-endian order sse load store instructions require 16-byte alignment function properly simd instruction sets also include prefetch instructions perform load target register used cache loading sse instruction sets also include non-temporal store instructions perform stores straight memory without performing cache allocate destination already cached otherwise behave like regular store generic integer floating point simd instructions use one parameter complex address second source parameter integer instructions also accept one memory parameter destination operand x86 assembly unconditional jump operation codice_105 take immediate address register indirect address parameter note risc processors support link register short immediate displacement jumping also supported several conditional jumps including codice_106 jump zero codice_107 jump non-zero codice_108 jump greater signed codice_109 jump less signed codice_110 jump above/greater unsigned codice_111 jump below/less unsigned conditional operations based state specific bits e flags register many arithmetic logic operations set clear complement flags depending result comparison codice_112 compare codice_113 instructions set flags performed subtraction bitwise operation respectively without altering values operands also instructions codice_114 clear carry flag codice_115 complement carry flag work flags directly floating point comparisons performed via codice_116 codice_117 instructions eventually converted integer flags jump operation three different forms depending size operand short jump uses 8-bit signed operand relative offset current instruction near jump similar short jump uses 16-bit signed operand real protected mode 32-bit signed operand 32-bit protected mode far jump one uses full segment base offset value absolute address also indirect indexed forms addition simple jump operations codice_10 call subroutine codice_11 return subroutine instructions transferring control subroutine codice_10 pushes segment offset address instruction following codice_10 onto stack codice_11 pops value stack jumps effectively returning flow control part program case codice_123 segment base pushed following offset codice_124 pops offset segment base return also two similar instructions codice_125 interrupt saves current e flags register value stack performs codice_123 except instead address uses interrupt vector index table interrupt handler addresses typically interrupt handler saves cpu registers uses unless used return result operation calling program software called interrupts matching return interrupt instruction codice_127 restores flags returning soft interrupts type described used operating systems system calls also used debugging hard interrupt handlers hard interrupts triggered external hardware events must preserve register values state currently executing program unknown protected mode interrupts may set os trigger task switch automatically save registers active task using interrupt 21h output – samples use libc printf print stdout flags heavily used comparisons x86 architecture comparison made two data cpu sets relevant flag flags following conditional jump instructions used check flags branch code run e.g flags also used x86 architecture turn certain features execution modes example disable maskable interrupts use instruction flags register also directly accessed low 8 bits flag register loaded codice_128 using codice_129 instruction entire flags register also moved stack using instructions codice_101 codice_102 codice_125 including codice_133 codice_127 instruction pointer called codice_135 16-bit mode codice_136 32-bit mode codice_137 64-bit mode instruction pointer register points memory address processor next attempt execute directly accessed 16-bit 32-bit mode sequence like following written put address codice_138 codice_62 sequence instructions generates position-independent code codice_10 takes instruction-pointer-relative immediate operand describing offset bytes target instruction next instruction case 0 writing instruction pointer simple — codice_105 instruction sets instruction pointer target address example sequence like following put contents codice_62 codice_136 64-bit mode instructions reference data relative instruction pointer less need copy value instruction pointer another register
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Computer architecture
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xcat xcat extreme cloud administration toolkit open-source distributed computing management software developed ibm used deployment administration linux aix based clusters xcat xcat specific features designed take advantage ibm hardware including xcat achieved recognition june 2008 used ibm roadrunner set computing speed record time xcat default systems management tool ibm intelligent cluster solution xcat used lenovo
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Distributed computing architecture
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cyberquery cyberquery software product cyberscience corporation inc originally developed data handling analysis data general aos aos/vs minicomputers available platforms cyberquery extended major unix platforms vax/vms digital equipment corporation personal computers microsoft windows invented 1980 cyberquery declarative 4gl fourth-generation programming language early design slightly influenced ramis data access analysis languages query language ge time sharing systems cyberquery automates process accessing files tables reading records rows basic operation allows user/developer concentrate details working data within record effect working almost entirely within implicit program loop runs record compared general-purpose programming languages automation allows user/developer ignore technical details data stored concentrate information contained data cyberquery data dictionary describe datasets users wish access removes physical details file structure program user/developer original target customers cyberquery personnel departments ease use non computer specialists early design goal architecture advantage cyberquery portable reports written one database run unmodified provided underlying data logically similar differences hidden data dictionary cyberquery widely deployed industries including manufacturing finance medical retail
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Programming language topics
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military cryptanalytics military cryptanalytics milcryp sometimes known revision lambros d. callimahos series books written william f. friedman title military cryptanalysis may also contain contributions cryptanalysts training manual national security agency military cryptanalysts published government use 1957 1977 though parts ii written 1956 1959 introduction part volume callimahos text represents extensive expansion revision scope content earlier work entitled 'military cryptanalysis part william f. friedman expansion revision necessitated considerable advancement made art since publication previous text callimahos referred parts iii–vi end first volume ... part iii deal varieties aperiodic substitution systems elementary cipher devices cryptomechanisms embrace detailed treatment cryptomathematics diagnostic tests cryptanalysis part iv treat transposition fractioning systems combined substitution-transposition systems part v treat reconstruction codes solution enciphered code systems part vi treat solution representative machine cipher systems however parts iv–vi never completed military cryptanalytics military cryptanalysis subjects foia requests including one john gilmore 1992-1993 two charles varga 2004 2016 four parts military cryptanalysis first two parts military cryptanalytics series declassified third part military cryptanalytics far released severely redacted form n't considered worth reprinting released portions repeat material first two parts 1984 nsa released copies military cryptanalytics parts ii us national archives records administration record group 457 srh-273 srh-274 respectively srh stands special research history declassified books reprinted aegean park press part military cryptanalytics consists two volumes first volume contains tutorial text second volume contains appendices part includes material uniliteral multiliteral ciphers polyalphabetic ciphers part ii includes material repeating-key bipartite systems periodic ciphers part ii volume ii includes zendian problem practical exercise traffic analysis cryptanalysis aegean park press edition wayne g. barker added programs trs-80
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Computer security
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social cloud computing social cloud computing also peer-to-peer social cloud computing area computer science generalizes cloud computing include sharing bartering renting computing resources across peers whose owners operators verified social network reputation system expands cloud computing past confines formal commercial data centers operated cloud providers include anyone interested participating within cloud services sharing economy turn leads options greater economies scale bearing additional advantages hosting data computing services closer edge may needed peer-to-peer p2p computing networking enable decentralized cloud computing area research sometime social cloud computing intersects peer-to-peer cloud computing social computing verify peer peer owner reputation thus providing security quality service assurances users demand computing environments may constructed altered statically dynamically across peers internet based available resources verified reputation provide assurances social cloud computing highlighted potential benefit large-scale computing video gaming media streaming tenets social cloud computing famously employed berkeley open infrastructure network computing boinc making service largest computing grid world another service uses social cloud computing subutai social subutai allows peer-to-peer sharing hardware resources well files globally within small network many challenges arise moving traditional cloud infrastructure social cloud environment case traditional cloud computing availability demand essential many cloud customers social cloud computing n't provide availability guarantee p2p environment peers mobile devices may enter leave p2p network time pcs primary purpose override p2p computation time relatively successful use cases recent years require real time results computation power small subset module larger algorithm data set unlike large scale data centers company brand image people may less likely trust peers vs. large company like google amazon running sort computation sensitive information would need encrypted properly overhead encryption may reduce usefulness p2p offloading resources distributed small pieces many peers computations inherent trust must placed client regardless encryption may promised client similar availability reliability computations must consistent uniform computations offloaded client continuously interrupted mechanism detecting must place client may know computation tainted needs completely re-run p2p social computing reliable expected computation power difficult achieve speed client calculation may depend much client using end device ways overcoming may allow computations occur night specified times client resources use
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Distributed computing architecture
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iostat iostat input/output statistics computer system monitor tool used collect show operating system storage input output statistics often used identify performance issues storage devices including local disks remote disks accessed network file systems nfs also used provide information terminal tty input output also includes basic cpu information codice_1 displays output line row gives numerical data one device first column lists device name subsequent columns show various statistics device columns include average service time svc_t includes time request service queue also seek time transfer time average busy percentage b essentially proportion time device use percentage time queue empty w means proportion time requests device yet fulfilled best run codice_2 specifying time interval seconds example codice_3 order see results time otherwise output reflect values entire timespan since system last rebooted codice_2 tool available unix unix-like operating systems freebsd macos com.apple.pkg.core package linux sysstat package solaris syntax output codice_2 often differs slightly sun microsystems stated high values wait svc_t fields suggest lack overall throughput system indicating system overloaded i/o operations consistently high values kr/s kw/s w b fields also indicate possible i/o bottleneck versions solaris solaris 7 iostat give misleading information wait field multiprocessor systems iostat misinterpret one processor state waiting i/o meaning processors system wait also advisable disregard high values svc_t field disks low rates activity less 5 fsflush process force average service time synchronising data disk memory iostat display information individual volumes disk volume manager used vxstat command used show information instead contrast using linux lvm volume manager iostat display volume information individually logical volume device mapper dm device
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Computer file systems
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pgpdisk pgp virtual disk disk encryption system allows one create virtual encrypted disk within file older versions windows nt freeware example bundled pgp v6.0.2i ckt builds pgp still available download longer maintained today pgp virtual disk available part pgp desktop product family running windows 2000/xp/vista mac os x
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Computer file systems
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alice k. hartley alice hartley 1937-2017 american computer scientist business woman hartley worked several dialects lisp implementing multiple parts interlisp maintaining macintosh common lisp developing concepts computer science programming language design still use today hartley hobby gamer playing advising early computer games 1970s 90s hartley also antiques collector importer dealer proprietor elephant castle antiques store boston hartley spent career researcher litton industries mit bbn early employee vice president technology paladian systems engineer apple computer retiring boston massachusetts alice hartley born bridgeport connecticut december 13 1937 lowell james hartley minneapolis minnesota rachel matilda virta aura finland hartley graduated whittier junior high school bridgeport connecticut highschool valedictorian class 1955 member newtonians science club cheerleader finalist fourteenth annual westinghouse science talent search hartley accepted mit 1955 general motors scholarship graduated msc physics june 12 1959 1961 alice hartley co-wrote “ study program pattern recognition research ” george sebestyen litton systems inc earliest record research-related employment outside mit following litton industries alice hartley worked senior scientist bbn technologies bolt beranek newman inc. early 1969 “ took dan murphy ’ role bbn lisp ” added number new data types system including “ arrays strings large numbers floating point numbers ” time bbn hartley co-developed concept spaghetti stack daniel g. bobrow form stack tracing functionality interlisp brought early debugging tools programming community hartley also worked douglas w. clark implementation list-linearizing garbage collector hartley listed maintainer interlisps basic system 1974 “ interlisp reference manual ” along side warren teitelman user facilities jw goodman special arithmetic functions reads a. k. hartley basic system i.e. interpreter input/output garbage collector plus subrs i.e hand-coded machine language functions print cons prog go etc plus compiler.hartley thanked paul graham introduction ansi common lisp mentioned collaborator guy steele evolution lisp hartley resigned bbn november 7th 1984 join new ai engineering firm palladian software inc vice president technology worked 1987 palladain hartley lead development various “ artificial inteligence ” systems financial modeling trading financial markets palladian software inc hartley worked apple computers allegro common lisp tools using lisp macintosh hartley single handedly maintained macintosh common lisp 2007 open-sourced source code llgpl
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Programming language topics
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security target common criteria information technology security evaluation version 3.1 part 1 called cc 3.1 cc defines security target st implementation-dependent statement security needs specific identified target evaluation toe words st defines boundary specifies details toe product evaluation process according cc st document provided vendor product st defines information assurance security functional requirements given information system product called target evaluation toe st complete rigorous description security problem terms toe description threats assumptions security objectives security functional requirements sfrs security assurance requirements sars rationales sars typically given number 1 7 called evaluation assurance level eal indicating depth rigor security evaluation usually form supporting documentation testing product meets sfrs st contains detailed implementation-specific information demonstrates product addresses security requirements may refer one protection profiles pps case st must fulfill generic security requirements given pps may define requirements 1 introduction – overview toe including key features purpose 2 conformance claims – identifies conformance claims toe evaluation 3 security problem definition describes threats assumptions operational environment objective demonstrate security problem intended addressed toe operational environment 4 security objectives – concise abstract statement intended solution problem specified security problem definition security objective must trace back least one threat osp 1 aspect security achieve purpose objective using certain mitigation measures confidentiality integrity availability user authenticity access authorisation accountability 2 confidentiality integrity availability required support applicable foundational requirements.- 5 extended components definition – extended components must consist measurable objective elements conformance demonstrated 6 security requirements defines describes sfrs cc part 2 sars cc part 3 7.toe summary specifications enables evaluators potential consumers gain general understanding toe implemented
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Computer security
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norwegian ship registers norwegian ship registers sometimes called nis-nor norwegian government agency responsible operating norwegian international ship register norwegian ship register norwegian shipbuilding register register subordinate norwegian ministry trade industry ministry transport based bergen
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Databases
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rkhunter rkhunter rootkit hunter unix-based tool scans rootkits backdoors possible local exploits comparing sha-1 hashes important files known good ones online databases searching default directories rootkits wrong permissions hidden files suspicious strings kernel modules special tests linux freebsd rkhunter notable due inclusion popular operating systems fedora debian etc tool written bourne shell allow portability run almost unix-derived systems 2003 developer michael boelen released version rootkit hunter several years development early 2006 agreed hand development development team since time eight people working set project properly work towards much-needed maintenance release project since moved sourceforge
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Computer security
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m32r m32r 32-bit risc instruction set architecture isa developed mitsubishi electric embedded microprocessors microcontrollers isa owned renesas electronics corporation company designs fabricates m32r implementations m32r processors used embedded systems engine control units digital cameras pdas isa supported linux gnu compiler collection dropped linux kernel version 4.16
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Computer architecture
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apple a4 apple a4 32-bit package package pop system-on-a-chip soc designed apple inc. manufactured samsung combines arm cortex-a8 cpu powervr gpu emphasizes power efficiency chip commercially debuted release apple ipad tablet followed shortly iphone 4 smartphone ipod touch 4th generation apple tv 2nd generation superseded apple a5 processor used ipad 2 released following year subsequently replaced apple a5x processor ipad 3rd generation software updates devices using chip ceased 2014 release ios 8 apple a4 based arm processor architecture first version released runs 1 ghz ipad contains arm cortex-a8 cpu core paired powervr sgx 535 graphics processor gpu built samsung 45 nm silicon chip fabrication process clock speed units used iphone 4 ipod touch 4th generation 800 mhz clock speed unit used apple tv released cortex-a8 core used a4 thought use performance enhancements developed chip designer intrinsity subsequently acquired apple collaboration samsung resulting core dubbed hummingbird able run far higher clock rates implementations remaining fully compatible cortex-a8 design provided arm performance improvements include additional l2 cache cortex-a8 cpu core used a4 also used samsung s5pc110a01 soc a4 processor package contain ram supports pop installation top package a4 used ipad ipod touch 4th gen apple tv 2nd gen contains two low-power 128 mb ddr sdram chips total 256 mb ram iphone 4 two chips 256 mb total 512 mb ram connected processor using arm 64-bit-wide amba 3 axi bus twice width memory buses socs used contemporary apple iphone ipod touch supporting greater need graphics bandwidth ipad apple a4 chip along original ipad announced january 27 2010 apple latest creation event june 7 2010 steve jobs publicly confirmed iphone 4 would contain a4 processor although yet known time would frequency bus width caches a4 found earlier produced ipad september 1 2010 ipod touch 4th generation apple tv 2nd generation updated include a4 processor later october 4 2011 apple refreshed ipod touch 4th generation add white model along existing black model models still contain a4 processor september 10 2013 apple a4 chip discontinued
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Computer architecture
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cifas cifas fraud prevention service united kingdom not-for-profit membership association representing organisations across public private voluntary sectors 2016 cifas 360 member organisations cifas states mission ‘ detect deter prevent fraud society harnessing technology working partnership ’ cifas operates two core fraud prevention databases largest uk national fraud database internal fraud database systems also used banks building societies access home office immigration data specialist portal data cifas members revealed instances identity fraud uk reached record levels 2016 particularly among people aged 30 trend continued 2017 cifas reporting 89,000 cases identity fraud first six months year cifas data 2016 2017 also highlighted growing issue money mules – people allow bank accounts used launder money cifas reported number young people 18-24-year-olds allowing accounts used transfer proceeds crime risen unprecedented 75 per cent last year cifas established 1988 consumer credit trade association ccta acronym cifas credit industry fraud avoidance system although company longer operates acronym remit broadened developed association office fair trading well information commissioner office continue day take active interest development cifas cifas today run board directors includes independent directors chief executive deputy chief executive 1988 2016 majority directors elected participating organisations participate governance organisation advisory board cifas national fraud database allows participating organisations exchange confirmed details applications products services considered fraudulent exchange confirmed information accounts services fraudulently misused confirmed information insurance claims considered fraudulent organisations also exchange information innocent victims fraud protect fraud internal fraud database allows participating organisations exchange details confirmed cases applicant member staff acted fraudulently data protection act individual right make subject access request cifas accordance act disclose data held individual statutory fee cifas credit reference agency 2014 immigration act became law cifas named sole provider home office immigration data launched cifas immigration portal cip december 2014 current account-providing banks building societies uk required use cip access home office data disqualified persons victims identity fraud people risk identity fraud apply cifas protective registration fee protective registration acts warning organisation carry additional checks verify identity applicant customer cifas also operates protecting vulnerable scheme helps local authorities protect individuals subject mental capacity act 2005 care cifas works fraud prevention financial public sector academic charitable organisations law enforcement raise awareness fraud promote best practice fraud prevention collaborative partners include city london police cipfa home office age uk financial fraud action uk cifas member joint fraud taskforce set former home secretary theresa may 2015
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Databases
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plasmapper plasmapper plasmid mapper freely available web server automatically generates annotates high-quality circular plasmid maps particularly useful online service molecular biologists wishing generate plasmid maps without purchase maintain expensive commercial software plasmapper accepts plasmid/vector dna sequence input fasta format uses sequence pattern matching blast sequence alignment automatically identify label common promoters terminators cloning sites restriction sites reporter genes affinity tags selectable marker genes origins replication open reading frames plasmapper reformats presents identified features simple textual form high-resolution multicolored image appearance content output customized numerous ways using variety online options plasmapper images rendered rasterized portable network graphics png jpg scalable vector graphics svg formats accommodate variety user needs preferences images textual output sufficient quality may used directly publications presentations
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Web technology
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placenames database ireland placenames database ireland also known logainm.ie database archive place names ireland created fiontar dublin city university collaboration placenames branch department culture heritage gaeltacht website public resource primarily aimed journalists translators students teachers historians researchers genealogy placenames commission established department finance 1946 advise ordnance survey ireland government irish name places placenames commission ceased 11 october 2012 placenames committee took place 19 september 2013 placenames branch branch department culture heritage gaeltacht established official languages act 2003 supports placenames commission/committee investigating historical irish-language names places although 1922 constitution irish free state current constitution adopted 1937 make irish national language law regard placenames carried 19th-century uk statutes established ordnance survey griffith valuation english-language name official status irish-language names adopted place english-language names 1920 e.g king county became laois kells county meath became ceannanus mór department posts telegraphs adopted irish names ad-hoc sometimes inconsistent disputed locals irish-language scholars 1973 oireachtas passed act codify official assignment irish names alongside rather instead english names 1975 first statutory instrument made 1973 gave official irish names post towns names chosen advice placenames branch differed adopted previous decades cases causing controversy 1973 act replaced 2003 act terms placenames committee continues advise minister prior issuing statutory instruments database website www.logainm.ie european language label 2010 category winner 2011 2016 irish egovernment awards
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Databases
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semantometrics semantometrics tool evaluating research functionally extension tools bibliometrics webometrics altmetrics instead evaluating citations – entails relying outside evidence – uses semantic evaluation full text research paper evaluated
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Computational linguistics
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igmp snooping igmp snooping process listening internet group management protocol igmp network traffic control delivery ip multicasts network switches igmp snooping listen igmp conversation hosts routers maintain map links need ip multicast transmission multicasts may filtered links need conserving bandwidth links switch default flood multicast traffic ports broadcast domain vlan equivalent multicast cause unnecessary load host devices requiring process packets solicited purposefully exploited form basis denial-of-service attack igmp snooping designed prevent hosts local network receiving traffic multicast group explicitly joined provides switches mechanism prune multicast traffic links contain multicast listener igmp client essentially igmp snooping layer 2 optimization layer 3 igmp igmp snooping takes place internally switches protocol feature igmp snooping allows switch forward multicast traffic links solicited snooping therefore especially useful bandwidth-intensive ip multicast applications iptv igmp snooping although important technique overlaps two standards organizations namely ieee standardizes ethernet switches ietf standardizes ip multicast means clear standards body responsible technique igmp snooping carries informational status despite actually referred standards work normative order igmp thus igmp snooping function multicast router must exist network generate igmp queries without querier igmp membership reporting may incomplete tables associating member ports multicast groups potentially incomplete snooping work reliably igmp snooping implementations include full querier capability igmpv2 igmpv3 contain provision selecting querier multiple available querier lowest ip address given role igmp general queries querier must unconditionally forwarded switches involved igmp snooping igmp snooping proxy reporting report suppression actively filters igmp packets order reduce load multicast router joins leaves heading upstream router filtered minimal quantity information sent switch trying ensure router single report group regardless many active listeners two active listeners group first one leaves switch determines router need information since affect status group router point view next time routine query router switch forward reply remaining host presence proxy reporting router generally know recently joined member group
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Internet protocols
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attack surface analyzer attack surface analyzer tool created analysis changes made attack surface operating systems since windows vista beyond tool recommended microsoft sdl guidelines verification stage development according microsoft sdl team one tool checking changes made attack surface windows operating system attack surface analyzer developed problem check verify effects various software installations system way back since windows server 2003 developed back use multiple tools every type change made attack surface painful process check everything using multiple tools problem made microsoft create application developers could analyze changes made windows attack surface first used developers microsoft later january 18 2011 beta version version 5.1.3.0 tool named attack surface analyzer released public testers administrators attack surface analyzer compare two scan data system called baseline scan product scan 32-bit 64-bit versions software available windows vista windows 7 respective server editions news windows xp version released attack surface analyzer one tool analysis changes made various parts attack surface windows 6 series operating system includes windows vista windows 7 using one tool analyze changes made registry file permissions windows iis server gac assemblies lot done according microsoft tool use engineers security team microsoft analyze effects software installation windows operating system would possible one tool would use different software different parts windows combine effects logically tool enlists various elements enumerates running system scan elements list comprehensive set elements possible well important elements changed new software installed system software might change elements list change different elements system attack surface analyzer combines easier analyze parts attack surface analyzer tell changes sure cases also able tell particular change configuration causing threat tool enlist threats categories parts operating system scans noticeable issues services configurations file system acls issues related processes running system getting list threats system great thing software released microsoft one knows windows better microsoft improved concerns security shown microsoft important severity threat also known team enterprise attack surface analyzer also shows severity threats finds however seems report severity every threat instead shows severity threat category example severity threat caused “ executables weak acls ” threat severity level 1 less caused “ processes impersonation tokens ” threat severity level 2 surely desirable feature enlist level severity caused threat rather category belongs however news might available every organization experts various domains security may case network security expert organization aware details terminology domain say windows services however two issues may connected possible case important experts two security expert teams know everything terms use might required cases brief description along link technet library describing term detail threats changes attack surface enlisted report generated attack surface analyzer brief description usually enough experts might needed cases microsoft made easy find right resource term rather relying upon web search engines attack surface windows operating system concerns various parts operating system would difficult anyone understand report changes listed serial order attack surface analyzer makes easy user browse report listing threats categories providing table contents html page attack surface analyzer compare two scan data generated two different scans generate report viewed html format also possible run scans one system generate another system using tool good windows vista clients possible generate report using current version attack surface analyzer windows vista case attack surface analyzer used run scans windows vista client transfer scan result files computer running windows 7 generate browse report windows 7 based computer attack surface analyzer works windows 6.x series operating systems report generation done 6.1 version operating systems following system requirements attack surface analyzer official download page installable windows vista windows 7 windows server 2008 windows server 2008 r2 collection attack surface data windows vista windows 7 windows server 2008 windows server 2008 r2 analysis attack surface data report generation windows 7 windows server 2008 r2 microsoft .net 3.5 sp1 microsoft enlisted hardware requirements separately tool able perform job machine meeting hardware requirements installed operating system note however running time generation scan data report depends hardware capabilities better hardware would get work done faster attack surface analyzer list two types scans namely baseline scan product scan strict technical terms scans difference logical technical scan run user run generate data initial system data compared product scan running baseline scan product whose effect attack surface operating system checked installed installation changes system configuration possibly installing services changing firewall rules installing new .net assemblies baseline scan logical scan run user using attack surface analyzer generates file containing configuration system software installed product scan signifies state system ‘ product ’ installed context product software whose effects system upon installation checked generate report two scans required minimum product scan would capture changes made system installation software product testing scan data generated scan compared baseline scan data find changes made system configurations different points worth note one system state captured using attack surface analyzer combination used report generation however ‘ baseline scan ’ one taken automatically called product scan
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Computer security
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warewulf warewulf computer cluster implementation toolkit facilitates process installing cluster long term administration changing administration paradigm make slave node file systems manageable one point automate distribution node file system node boot allows central administration model slave nodes includes tools needed build configuration files monitor control nodes totally customizable adapted type cluster software administration perspective make much difference running 2 nodes 500 nodes procedure still warewulf scalable admins perspective also uses standard chroot'able file system every node extremely configurable lends custom environments easily warewulf designed hpc system hpc system warewulf along lines distributed linux distribution specifically system replicating managing small lightweight linux systems one master using warewulf hpc packages lam/mpi/mpich sun grid engine pvm etc easily deployed throughout cluster warewulf solves problem slave node management rather strict hpc specific system even though designed hpc mind flexible home grown cluster administratively scales well result flexibility ease customization warewulf used production hpc implementations also development systems like kasy0 first system break one hundred dollar per gflops barrier non hpc systems web server cluster farms intrusion detection clusters high-availability clusters
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Distributed computing architecture
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proportional set size computing proportional set size pss portion main memory ram occupied process composed private memory process plus proportion shared memory one processes unshared memory including proportion shared memory reported pss example since pss defined sum unshared memory process proportion memory shared processes pss two processes follows concept mostly related unique linux operating system proposed matt mackall complications arose trying count real memory used process concepts resident set size virtual memory size vmsize n't helping developers tried know much memory programs using
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Operating systems
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crypt unix unix computing crypt utility program used encryption due ease breaking considered obsolete cryptographer robert morris wrote crypt first appeared version 3 unix encourage codebreaking experiments morris managed break crypt hand dennis ritchie automated decryption method james reeds improved version appeared version 7 reeds peter j. weinberger also broke also unix password hash function name crypt though used encrypting data sense otherwise essentially unrelated distinguish two writers often refer utility program crypt 1 documented section 1 unix manual pages refer password hash function crypt 3 documentation section 3 manual crypt 1 simple command encrypt decrypt data usually used filter traditionally implemented using algorithm based enigma machine considered cryptographically far weak provide security brute-force attacks modern commodity personal computers versions unix shipped even weaker version crypt 1 command order comply contemporaneous laws regulations limited exportation cryptographic software simply implementations caesar cipher effectively secure rot13 implemented caesar cipher well-known key linux distributions generally include unix compatible version crypt command largely due combination three major factors source code several old versions crypt command available unix heritage society unix archive recent crypt source code available opensolaris project enhanced symmetric encryption utilities available linux also portable unix-like system including mcrypt ccrypt provide support much sophisticated modern algorithms used encrypt decrypt files compatible traditional crypt 1 command providing correct command line options programs breaking crypt 1 encryption widely available bob baldwin crypt breaker workbench written 1984-1985 interactive tool provides successive plaintext guesses must corrected user peter selinger unixcrypt-breaker uses simple statistical model guess plausible plaintexts require user interaction
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Computer security
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plug computer plug computer external device often configured use home office compact computer consists high-performance low-power system-on-a-chip processor several i/o ports usb ports ... typically runs number linux distributions versions provisions connecting display best suited running media server back-up services file sharing remote access functions thus acting bridge in-home protocols digital living network alliance dlna server message block smb cloud based services however plug computer offerings analog vga monitor and/or hdmi connectors along multiple usb ports permit use display keyboard mouse thus making full-fledged low-power alternatives desktop notebook computers name plug computer derived small configuration devices plug computers often enclosed ac power plug ac adapter plug computers typically consume little power inexpensive one manufacturer claims 119 plug computer draws 1.2 watts cost 2 year run number devices type began appear 2009 consumer electronics show chippc another one
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Distributed computing architecture
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ukcloud ukcloud previously named skyscape cloud services british public cloud company headquartered farnborough united kingdom one largest uk cloud providers company founded 2011 rebranding ukcloud august 2016 ukcloud cloud provider several customers including genomics england ministry justice cabinet office amongst others company established 2011 co-founders jeff thomas jeremy sanders phil dawson simon hansford skyscape cloud services changed name ukcloud ltd five years later following legal wrangle sky ukcloud services provided partnership qinetiq vmware cisco dell emc ark data centres ukcloud focuses changing uk government purchases uses services detailed march 2011 uk government ict strategy company since sold government g-cloud frameworks digital marketplace since first iteration framework 2012 offer multi-cloud platform consisting vmware oracle openstack microsoft azure ukcloud subject regular audits assessments inspections certification bodies regulators accreditors firm recently achieved iso27017 iso27018 also certified iso9001 iso20000 iso27001 ukcloud carbon neutral company offers customers carbon neutral hosting achieved independent assessment co2 emissions produced direct indirect sources required deliver followed offset-inclusive emissions reduction programme ukcloud also completely sovereign cloud provider meaning applications data hosted uk datacentres company incorporated british company uk legal jurisdiction 2016 ukcloud communications deloitte technology fast 500 emea award also cloudex 20:20 award uk industry award 2013. winners sunday times hiscox tech track 100 2016 ukcloud winners tech track 100 ranking number 1 league table 2016 2017 ukcloud announced recipients prestigious queen ’ awards enterprise innovation 2018 ukcloud award g-cloud public sector provider year second year consecutively company also featured one future fifty ’ fastest growing technology companies addition founding alliance partners ukcloud since announced cloud native cloud platform based upon redhat openstack oracle cloud platform
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Distributed computing architecture
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xymon xymon network monitoring application using free software operates gnu general public license central server runs unix linux hosts application inspired open-source version big brother network monitoring application maintains backward compatibility 2002 2004 henrik storner wrote open-source software add-on called bbgen toolkit march 2005 stand-alone version released called hobbit versions released 2005 2008 since prior user trademark hobbit existed tool finally renamed xymon january 2012 quest software discontinued development big brother xymon offers graphical monitoring showing status various network services device well range application operating system metrics listing number mail messages queued defined level downtime web-based graphical display uses red/yellow/green condition icon host/test top colored background indicating current worst status across hosts tests user click colored icon view specific details available relevant graphs metric statistics built-in reporting tools include sla-type reports availability historical state services snapshots xymon supports generation alarms sent email also use external tools send messages via means eg sms networked hosts devices monitored xymon server using network probes supporting large extensible range protocols including smtp http/s dns hosts use supported operating system also run xymon client also free software additionally collect operating system application monitoring metrics report xymon server clients available unix linux formats including source tarball rpm debian package xymon download site sourceforge windows hosts use big brother client windows bbwin client winpsclient written windows powershell scripting language plugins extend monitoring new types applications services many extension scripts big brother run unchanged xymon
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Computer security
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bicycle attack tls bicycle attack refers method discovering password length encrypted packets transmitted via ssl https term first coined december 30 2015 guido vranken wrote premise bicycle attack makes brute-forcing passwords much easier length passwords known moreover refutes idea ssl-encrypted http packets obscure length
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Computer security
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open source business alliance open source business alliance e.v german non-profit operates europe biggest network companies organizations developing building using open source software alliance founded july 2011 stuttgart two founding associations linux solutions group e.v lisog live linux-verband e.v. officially merged groups annual general meetings 20th 21 july 2011 merger aimed create unified lobby group german open-source movement 2014 attempted consolidation failed osb alliance open source business foundation osbf first announced intention merge two associations form single large advocacy group 18 november 2013 almost year negotiations achieved agreement merger collapsed 15 october 2014 alliance main aims central objectives alliance current board open source business alliance e.v consists 11 members honorary chairman osb alliance supports working groups cover wide range issues january 2015 following working groups operation
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Operating systems
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zerofox zerofox cyber security company based baltimore maryland provides cloud-based software service saas organizations detect risks found social media digital channels phishing malware scams impersonator accounts piracy counterfeit zerofox created 2013 name riskive changed current name months later company began startup 8,000 sq ft. space inside betamore startup incubator baltimore federal hill neighborhood 2015 zerofox raised 27 million series b funding 2016 company outgrown space moved 18,000 sq ft. space inside former pabst brewing facility south baltimore 2017 zerofox raised 40 million funding led redline capital management european venture firm silver lake waterman fund focuses pre-ipo companies prior investors new enterprise associates highland capital partners core capital also contributed investment helped bring zerofox ’ total funding 88 million
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Computer security
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dnix dnix original spelling d-nix unix-like real-time operating system swedish company dataindustrier ab diab version called abcenix also developed abc1600 computer luxor daisy systems also something called daisy dnix cad workstations unrelated diab product dataindustrier ab literal translation computer industries shareholding company started 1970 lars karlsson single-board computer manufacture sundsvall sweden producing zilog z80-based computer called data board 4680 1978 diab started work swedish television company luxor ab produce home office computer series abc 80 abc 800 1983 diab independently developed first unix-compatible machine diab ds90 based motorola 68000 cpu d-nix made appearance based unix system v license diab however industrial automation company needed real-time operating system company replaced t-supplied unix kernel in-house developed yet compatible real-time variant kernel originally z80 kernel called os8 time company also replaced several unix standard userspace tools implementations point code derived unix machines could deployed independently unix license two years later cooperation luxor computer called abc 1200 developed office market parallel diab continue produce enhanced versions ds90 computer using newer versions motorola cpus motorola 68010 68020 68030 eventually 68040 1990 diab acquired groupe bull continued produce support ds machines brand name diab names diab 2320 diab 2340 etc. still running diabs version dnix isc systems corporation isc purchased right use dnix late 1980s use line motorola 68k-based banking computers isc later bought olivetti turn resold wang bought getronics corporate entity often referred 'isc answered bewildering array names years code branch svr2 compatible version received extensive modification development hands notable features operating system support demand paging diskless workstations multiprocessing asynchronous i/o ability mount processes handlers directories file system message passing real-time support consisted largely internal event-driven queues rather list search mechanisms 'thundering herd static process priorities two classes run completion timesliced support contiguous files avoid fragmentation critical resources memory locking quality orthogonal asynchronous event implementation yet equalled current commercial operating systems though approach concept yet adopted synchronous marshalling point asynchronous activity could asynchronous ad infinitum dnix handled aplomb asynchronous i/o facility obviated need berkeley sockets select svr4 streams poll mechanism though socket emulation library preserved socket semantics backward compatibility another feature dnix none standard utilities ps frequent offender rummaged around kernel memory job system calls used instead meant kernel internal architecture free change required handler concept allowed network protocol stacks outside kernel greatly eased development improved overall reliability though performance cost also allowed foreign file systems user-level processes improved reliability main file system though could external process pulled kernel performance reasons dnix could well considered microkernel though formally developed handlers could appear type 'native unix file directory structure device file i/o requests handler could process could passed handlers including underlying one upon handler mounted handler connections could also exist passed around independent filesystem much like pipe one effect tty-like 'devices could emulated without requiring kernel-based pseudo terminal facility example handler saved day isc diskless workstation support bug implementation meant using named pipes workstation could induce undesirable resource locking fileserver handler created workstation field accesses afflicted named pipes appropriate kernel fixes could developed handler required approximately 5 kilobytes code implement indication non-trivial handler need large isc also received right manufacture diab ds90-10 ds90-20 machines file servers multiprocessor ds90-20 however expensive target market isc designed servers ported dnix isc designed gui-based diskless workstations use file servers ported dnix though isc used daisy workstations running daisy dnix design machines would run diab dnix negligible confusion internally drafting layout staff rarely talked software staff moreover hardware design staff n't use either system running joke went something like isc build computers n't use asynchronous i/o support dnix allowed easy event-driven programming workstations performed well even though relatively limited resources gui diskless workstation 7 mhz 68010 processor usable 512k memory kernel consumed approximately half workstations 1 mb memory though later 2 mb 4 mb versions along 10 mhz processors full-blown installation could consist one server 16 mhz 68020 8 mb ram 200 mb hard disk 64 workstations though slow boot array would perform acceptably bank teller application besides innate efficiency dnix associated diab c compiler key high performance generated particularly good code 68010 especially isc got done isc also retargeted texas instruments tms34010 graphics coprocessor used last workstation diab c compiler course used build dnix one factors contributing efficiency still available form wind river systems systems still use writing 2006 former seattle-first national bank branches branded bank america may probably isc customers still using dnix capacity isc considerable dnix presence central south america dnix native system call dnix 2 library function analogous standard unix unix 2 syscall 2 function took multiple arguments first function code semantically single call provided appropriate unix functionality though syntactically different unix course numerous dnix-only extensions dnix function codes organized two classes type 1 type 2 type 1 commands associated i/o activity anything could potentially cause issuing process block major examples f_open f_close f_read f_write f_iocr f_iocw f_wait f_nap type 2 remainder f_getpid f_gettime etc could satisfied kernel immediately invoke asynchronicity special file descriptor called trap queue created via type 2 opcode f_otq type 1 call would f_nowait bit or-ed function value one additional parameters dnix 2 trap queue file descriptor return value asynchronous call normal value kernel-assigned identifier time asynchronous request completed read 2 f_read trap queue file descriptor would return small kernel-defined structure containing identifier result status f_cancel operation available cancel asynchronous operation n't yet completed one arguments kernel-assigned identifier process could cancel requests currently owned exact semantics cancellation request handler fundamentally meant waiting terminated partially completed operation could returned addition kernel-assigned identifier one arguments given asynchronous operation 32-bit user-assigned identifier often referenced function pointer appropriate subroutine would handle i/o completion method merely convention entity read trap queue elements responsible interpreting value note asynchronous events gathered via normal file descriptor read operations reading capable made asynchronous implications semi-autonomous asynchronous event handling packages could exist within single process dnix 5.2 lightweight processes threads also note potentially blocking operation capable issued asynchronously dnix well equipped handle many clients single server process process restricted one trap queue i/o requests could grossly prioritized way addition native dnix 2 call complete set 'standard libc interface calls available open 2 close 2 read 2 write 2 etc besides useful backwards compatibility implemented binary-compatible manner ncr tower computer binaries compiled would run unchanged dnix dnix kernel two trap dispatchers internally one dnix method one unix method choice dispatcher programmer using interchangeably acceptable semantically identical wherever functionality overlapped machines 68000 trap 0 instruction used unix 2 calls trap 4 instruction dnix 2 two trap handlers really quite similar though usually hidden unix 2 call held function code processor d0 register whereas dnix 2 held stack rest parameters dnix 5.2 networking protocol stacks internally except thin x.25-based ethernet protocol stack added isc use diskless workstation support package networking conducted reading writing handlers thus socket mechanism libsocket 3 existed used asynchronous i/o talk tcp/ip handler typical berkeley-derived networking program could compiled run unchanged modulo usual unix porting problems though might efficient equivalent program used native asynchronous i/o dnix process could used handle i/o requests extend filesystem process called handler major feature operating system handler defined process owned least one request queue special file descriptor procured one two ways f_orq f_mount call former invented isolated request queue one end typically handed child process network remote execution programs many used method provide standard i/o paths children latter hooked filesystem file i/o requests could adopted handlers network login programs even used method provide standard i/o paths children semantics logging unix requires way multiple perhaps-unrelated processes horn standard i/o path operator mounted directory filesystem handler received i/o calls point handler would read small kernel-assigned request data structures request queue reading could done synchronously asynchronously handler author desired handler would whatever request required satisfied often using dnix f_uread f_uwrite calls read write request data space would terminate request appropriately using f_termin privileged handler could adopt permissions client individual requests subordinate handlers filesystem via f_t1req call n't need reproduce subordinate permission scheme handler unable complete request f_passrq function could used pass i/o requests one handler another handler could perform part work requested passing rest another handler common handler state-machine oriented requests fielding client done asynchronously allowed single handler field requests multiple clients simultaneously without blocking unnecessarily part request structure process id priority handler could choose work first based upon information requirement work performed order requested aid possible poll request trap queues see work considered buckling actually particular restriction number request queues process could used provide networking facilities chroot jails example give appreciation utility handlers isc handlers existed isc purchased 5.2 svr2 compatible 5.3 svr3 compatible versions dnix time purchase dnix 5.3 still undergoing development diab dnix 5.2 deployed time isc engineers incorporated 5.3 kernel features 5.2 primarily shared memory ipc divergence features diab isc versions dnix diab 5.3 likely went contain svr3 features isc 5.2 ended also diab went dnix 5.4 svr4 compatible os isc developers considerably extended version dnix 5.2 listed features involving kernel based upon needs general trends unix industry dnix development isc effectively ceased 1997 number planned os features left table
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Operating systems
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apparmor apparmor application armor linux kernel security module allows system administrator restrict programs capabilities per-program profiles profiles allow capabilities like network access raw socket access permission read write execute files matching paths apparmor supplements traditional unix discretionary access control dac model providing mandatory access control mac included mainline linux kernel since version 2.6.36 development supported canonical since 2009 addition manually creating profiles apparmor includes learning mode profile violations logged prevented log used generating apparmor profile based program typical behavior apparmor implemented using linux security modules lsm kernel interface apparmor offered part alternative selinux critics consider difficult administrators set maintain unlike selinux based applying labels files apparmor works file paths proponents apparmor claim less complex easier average user learn selinux also claim apparmor requires fewer modifications work existing systems example selinux requires filesystem supports security labels thus provide access control files mounted via nfs apparmor filesystem-agnostic apparmor represents one several possible approaches problem restricting actions installed software may take selinux system generally takes approach similar apparmor one important difference selinux identifies file system objects inode number instead path apparmor inaccessible file become accessible hard link created selinux inode-based model would still deny access newly created hard links hard link would pointing inaccessible inode selinux apparmor also differ significantly administered integrate system isolation processes also accomplished mechanisms like virtualization one laptop per child olpc project example sandboxes individual applications lightweight vserver 2007 simplified mandatory access control kernel introduced 2009 new solution called tomoyo included linux 2.6.30 like apparmor also uses path-based access control apparmor first used immunix linux 1998–2003 time apparmor known subdomain reference ability security profile specific program segmented different domains program switch dynamically apparmor first made available sles opensuse first enabled default sles 10 opensuse 10.1 may 2005 novell acquired immunix rebranded subdomain apparmor began code cleaning rewriting inclusion linux kernel 2005 september 2007 apparmor maintained novell novell suse legal owner trademarked name apparmor apparmor first successfully ported/packaged ubuntu april 2007 apparmor became default package starting ubuntu 7.10 came part release ubuntu 8.04 protecting cups default ubuntu 9.04 items mysql installed profiles apparmor hardening continued improve ubuntu 9.10 ships profiles guest session libvirt virtual machines evince document viewer optional firefox profile apparmor integrated october 2010 2.6.36 kernel release apparmor integrated synology dsm 5.1 beta 2014 apparmor enabled solus release 3 2017/8/15 apparmor enabled default debian 10 buster
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Operating systems
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snack sound toolkit snack sound toolkit cross-platform library written kåre sjölander swedish royal technical university kth bindings scripting languages tcl python ruby provides audio i/o audio analysis processing functions spectral analysis pitch tracking filtering related graphics functions display sound pressure waveform spectrogram available microsoft windows linux mac os x solaris hp-ux freebsd netbsd irix snack sound toolkit used number linguistic research tools including wavesurfer transcriber sndbite well applications snackamp mp3 music player used academic research delft university technology springer collection perception multimodal dialogue systems includes research essay utilizing snack human-computer speech interaction toolkit included component activestate tcl python distributions
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Computational linguistics
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adso application development system online adso tool used expedite writing testing modular applications using idms databases activities flow-of-control processing data storage definition data verification editing error handling terminal input output menu creation menu display specified using series screens instead conventional detailed code adso ads/o ads originally cullinet product later company acquired computer associates ads/o three components adsg adsa adsr tools used along ads/o develop ads/o application adso used develop online batch applications
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Databases
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microsoft notification protocol microsoft notification protocol msnp also known mobile status notification protocol instant messaging protocol developed microsoft use microsoft messenger service instant messaging clients connect skype since 2014 earlier windows live messenger msn messenger windows messenger microsoft messenger mac third-party clients pidgin trillian also communicate using protocol msnp first used publicly available product first release msn messenger 1999 major change made protocol new command syntax changes results version-number incremented one format msnp october 2003 microsoft started blocking access messenger service using versions msnp8 starting september 11 2007 microsoft forces current users msn messenger upgrade windows live messenger 8.1 due security considerations msnp1 never public believed used early stages design development msn messenger 1 pre-release version made available developers 1999 internet draft however production version differed published version subtle ways msnp2 msnp3 supported msn messenger 2.0 msnp3 4 5 supported messenger servers july 2000 used msn messenger 3.0 4.0 msnp6 used later versions msn messenger 4.x 2002 msn messenger 5.0 used msnp7 msnp8 introduced different authentication method sending authorization microsoft passport secure servers returning challenge string minimum version protocol accepted .net messenger service microsoft blocked earlier versions security reasons old obsolete clients unable sign forcing users upgrade clients version 5.0 msn messenger one uses msnp version windows messenger uses msnp8 standard version including 4.7 latest 5.1 protocol supports windows messenger-to-windows messenger webcam voice capabilities msnp9 introduced msn messenger 6 adding support type data messages used transferring display pictures custom emoticons clients frame-by-frame web cam rather traditional stream like windows media player wmv format improved voice system well improved nat traversal file transfers employed msn messenger 6.1 microsoft started blocking earlier versions october 2003 however big overhaul obvious change integration hotmail address books employed msn messenger 7.0 employed msn messenger 7.5 employed windows live messenger 8.0 msnp13 features lot changes notably contact list synchronization removed clients must instead send soap request contacts server also known client goes abch abch stands address book clearing house address book service behind msn windows live services client must send contacts data server send presence information msnp14 adds yahoo messenger interoperability msnp15 protocol version introduced windows live messenger 8.1 2006-09-08 based msnp14 uses different authentication mechanism called rps relying party suite twn tweener authentication used protocol versions 14 sso single sign-on rps authentication used protocol versions 15 addition new authentication mechanism microsoft also planning making properties user roaming user display picture future personal status messages wherever user signs furthermore support user locations added personal status message although feature later removed windows live messenger 8.1 client msnp16 used pre-release version windows live messenger 9.0 leaked december 2007 features multiple points presence mpop ability sign 2 places time chats replicated places uux data extended contain endpoint data also mpop well signature sound msn object data msnp17 identified windows live messenger servers messenger.hotmail.com unused official client released microsoft msnp18 used windows live messenger 2009 14.0 main new addition groups feature much like persistent grouped conversations uux data extended include scene image msn object data employed windows live messenger 2011 wave 4 employed windows live messenger 2012 employed skype since early 2014
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Internet protocols
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sparql sparql pronounced sparkle recursive acronym sparql protocol rdf query language rdf query language—that semantic query language databases—able retrieve manipulate data stored resource description framework rdf format made standard rdf data access working group dawg world wide web consortium recognized one key technologies semantic web 15 january 2008 sparql 1.0 became official w3c recommendation sparql 1.1 march 2013 sparql allows query consist triple patterns conjunctions disjunctions optional patterns implementations multiple programming languages exist exist tools allow one connect semi-automatically construct sparql query sparql endpoint example viziquer addition exist tools translate sparql queries query languages example sql xquery sparql allows users write queries loosely called key-value data specifically data follow rdf specification w3c thus entire database set subject-predicate-object triples analogous nosql databases usage term document-key-value mongodb sql relational database terms rdf data also considered table three columns – subject column predicate column object column subject rdf analogous entity sql database data elements fields given business object placed multiple columns sometimes spread across one table identified unique key rdf fields instead represented separate predicate/object rows sharing subject often unique key predicate analogous column name object actual data unlike relational databases object column heterogeneous per-cell data type usually implied specified ontology predicate value also unlike sql rdf multiple entries per predicate instance one could multiple child entries single person return collections objects like children thus sparql provides full set analytic query operations codice_1 codice_2 codice_3 data whose schema intrinsically part data rather requiring separate schema definition however schema information ontology often provided externally allow joining different datasets unambiguously addition sparql provides specific graph traversal syntax data thought graph example demonstrates simple query leverages ontology definition codice_4 friend friend specifically following query returns names emails every person dataset query joins together triples matching subject type predicate codice_5 person codice_6 person one names codice_7 mailboxes codice_8 author query chose reference subject using variable name codice_9 readable clarity since first element triple always subject author could easily used variable name codice_10 codice_11 whatever name chosen must line query signify query engine join triples subject result join set rows – codice_9 codice_13 codice_14 query returns codice_13 codice_14 codice_9 often complex uri rather human-friendly string note codice_9 may multiple mailboxes returned set codice_13 row may appear multiple times mailbox query distributed multiple sparql endpoints services accept sparql queries return results computed results gathered procedure known federated query whether federated manner locally additional triple definitions query could allow joins different subject types automobiles allow simple queries example return list names emails people drive automobiles high fuel efficiency case queries read data database sparql language specifies four different query variations different purposes query forms takes codice_24 block restrict query although case codice_23 query codice_24 optional sparql 1.1 specifies language updating database several new query forms another sparql query example models question country capitals africa variables indicated codice_27 codice_28 prefix bindings codice_29 codice_30 returned triple ends semicolon subject triple implicitly complete following pair entire triple example codice_31 short codice_32 sparql query processor search sets triples match four triple patterns binding variables query corresponding parts triple important note property orientation class matches conducted solely class-attributes properties – see duck typing make queries concise sparql allows definition prefixes base uris fashion similar turtle query prefix codice_33 stands “ nowiki http //example.com/exampleontology /nowiki ” geosparql defines filter functions geographic information system gis queries using well-understood ogc standards gml wkt etc. sparul another extension sparql enables rdf store updated declarative query language adding codice_34 codice_35 methods open source reference sparql implementations see list sparql implementations comprehensive coverage including triplestore apis storages implemented sparql standard
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Web technology
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sqlstate programs calling database accords sql standard receive indication success failure call return code called sqlstate consists 5 byte divided two parts first second byte contains class following three subclass class belongs one four categories denotes success class 00 w denotes warning class 01 n denotes data class 02 x denotes exception classes following table lists standard-conforming values based table last column shows part standard defines row empty definition origins part 2 foundation
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Databases
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visual objects visual objects object-oriented computer programming language used create computer programs operate primarily windows although used general-purpose programming tool almost exclusively used create database programs original visual objects project code-named aspen started part nantucket attempts bring clipper language windows move procedural object-oriented style also converted clipper p-code system true native compiler introduced elements c language typed variables including windows extensions com odbc later ado symbol datatype offers ability form name-based linkages may used connect menu events object methods form direct linkages server columns controls windows version finally brought market computer associates unfortunately released market-ready almost head-to-head competition first release borland delphi product language still use however last release grafx software 2012 version 2.8 sp4 version number 2838 grafx announced new versions would released next incarnation visual objects language vulcan.net written grafx scratch visual objects compatible true cls compliant .net language taking full advantage .net framework
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Programming language topics
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chromebox chromebox small form-factor pc running google chrome os operating system device debuted may 2012 chromeboxes like chrome os devices including chromebook laptops primarily support web applications thereby relying heavily internet connection software functionality data storage connection via local area network wireless ethernet port machines classed small form-factor pcs typically feature power switch set connections support keyboard pointing device one monitors solid state drives used storage wireless printers supported first chromebox released samsung may 29 2012 ran dual-core intel celeron processor 867 1.3 ghz featured six usb 2.0 ports two displayport++ slots compatible hdmi dvi vga february 2014 google bundled intel core i7 chromebox business video conferencing package 1080p high definition camera module external microphone/speaker remote control chromebox meetings system retailed 999 plus 250 annual management fee waived first year—a cost thousands dollars less unified videoconferencing systems including cisco polycom system employed google hangouts-like interface 15 participants dedicated url sharing screens management accounts scheduling meetings updated system announced november 2017 featured 4k camera machine learning feature automatically identifies frames participants march 2014 asus established new price low-end chromebox market compact 1.32 pound model retailed 179 featured celeron cpu four usb 3.0 ports yahoo tech columnist david pogue called asus device among smallest least-expensive desktop computers ever sold likening smart car ’ hauling lumber home depot ’ terrific deal—and days ’ get want go may asus released faster model intel core i3 processor hewlett-packard entered market june chromebox powered intel celeron processor optionally bundling keyboard mouse august acer introduced two models could stand vertically provided business-oriented features including encryption fast deletion local data september dell entered market entry-level machine well dell implementation google video conferencing system august 2015 aopen announced family chromeboxes designed principally driving content digital commercial signage models ruggedized on-site operation capability run android apps chrome os devices introduced google 2016 realized certain chromebooks 2017 seemed bypass chromeboxes cluster new chromebox offerings appeared 2018 including acer asus hp oregon-based ctl compute teach learn maker chromebooks since 2014 launched first chromebox march 2018
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Distributed computing architecture
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temporary variable computer programming temporary variable variable short lifetime usually hold data soon discarded placed permanent memory location short-lived usually declared local variable i.e. variable local scope formal definition makes variable temporary often-used term programming typical example would swapping contents two variables swap contents variables b one would typically use temporary variable temp follows preserve data overwritten b temporary variables usually named identifiers abbreviate word temporary temp tmp simply common metasyntactic variable names common foo bar baz see also foobar computer hardware designed exploit behaviour temporary data cache register file may contain temporaries internally microprocessor never need committed main memory hence consuming external memory bandwidth
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Programming language topics
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reconstructor reconstructor program allows anyone customize iso image ubuntu variants kubuntu xubuntu website longer functioning
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Operating systems
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adultswine adultswine malware discovered 2018 check point software technologies malware found programmed around 60 apps google play store primarily aimed children bug would display pornographic ads clicked would instruct victims download malicious software attempt steal personal data estimated 3 7 million users may infected according representative google apps removed play store developer accounts associated apps locked check point cautions users extra vigilant installing apps particularly intended use children ”
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Computer security
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hdiv hdiv web application security framework controls information flow server client avoiding many important web risks hdiv extends web applications behaviour adding security functionalities maintaining api framework specification implies hdiv may used applications developed spring mvc grails jstl struts 1 struts 2 javaserver faces symfony transparent way programmer without adding complexity application development
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Computer security
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ntfs volume mount point ntfs volume mount points specialized ntfs filesystem objects used mount provide entry point volumes mount points created directory ntfs file system gives reference root directory mounted volume empty directory converted mount point mounted volume limited ntfs filesystem formatted file system supported microsoft windows volume mount points supported ntfs 3.0 introduced windows 2000 though quite similar regular posix mount points found unix unix-like systems support local filesystems windows vista later ntfs symbolic links used link local directories remote smb network paths symbolic links work boot impossible redirect e.g nevertheless possible redirect
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Computer file systems
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aleph kernel aleph discontinued operating system kernel developed university rochester part rig project 1975 aleph early set road creation first practical microkernel operating system mach aleph used inter-process communications move data programs kernel applications could transparently access resources machine local area network time 3-mbit/s experimental xerox ethernet project eventually petered several years due rapid changes computer hardware market ideas led creation accent carnegie mellon university leading turn mach applications written rig system communicated via ports ports essentially message queues maintained aleph kernel identified machine unique opposed globally unique id consisting process id port id pair processes automatically assigned process number pid startup could ask kernel open ports processes could open several ports read automatically blocking allowing programs run data arrived processes could also shadow another receiving copy every message sent one shadowing similarly programs could interpose another receiving messages essentially cutting original message conversation rig implemented number data general eclipse minicomputers ports implemented using memory buffers limited 2 kb size produced significant overhead copying large amounts data another problem realized retrospect use global id allowed malicious software guess ports thereby gain access resources since ids based program id port ids changed program restarted making difficult write servers clients could rely specific port number service
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Computer architecture
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instruction cycle instruction cycle also known fetch–decode–execute cycle simply fetch-execute cycle cycle central processing unit cpu follows boot-up computer shut order process instructions composed three main stages fetch stage decode stage execute stage simpler cpus instruction cycle executed sequentially instruction processed next one started modern cpus instruction cycles instead executed concurrently often parallel instruction pipeline next instruction starts processed previous instruction finished possible cycle broken separate steps program counter pc special register holds memory address next instruction executed fetch stage address stored pc copied memory address register mar pc incremented order point memory address next instruction executed cpu takes instruction memory address described mar copies memory data register mdr mdr also acts two-way register holds data fetched memory data waiting stored memory also known memory buffer register mbr eventually instruction mdr copied current instruction register cir acts temporary holding ground instruction fetched memory decode stage control unit cu decode instruction cir cu sends signals components within cpu arithmetic logic unit alu floating point unit fpu alu performs arithmetic operations addition subtraction also multiplication via repeated addition division via repeated subtraction also performs logic operations binary shifts well fpu reserved performing floating-point operations computer cpu different cycles based different instruction sets similar following cycle cycle begins soon power applied system initial pc value predefined system architecture instance intel ia-32 cpus predefined pc value codice_1 typically address points set instructions read-only memory rom begins process loading booting operating system fetch step instruction control unit fetches instruction address memory unit decoding process allows cpu determine instruction performed cpu tell many operands needs fetch order perform instruction opcode fetched memory decoded next steps moved appropriate registers decoding done cpu control unit step evaluates type operation performed memory operation computer checks whether direct indirect memory operation i/o register instruction computer checks type executes instruction function instruction performed instruction involves arithmetic logic alu utilized stage instruction cycle useful perspective end user everything else overhead required make execute step happen
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Computer architecture
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compatibility c c++ c c++ programming languages closely related many significant differences c++ began fork early pre-standardized c designed mostly source-and-link compatible c compilers time due development tools two languages ides compilers often integrated single product programmer able specify c c++ source language however c subset c++ consequently c programs compile c++ code without modification likewise c++ introduces many features available c practice almost code written c++ conforming c code article however focuses differences cause conforming c code ill-formed c++ code conforming/well-formed languages behave differently c c++ bjarne stroustrup creator c++ suggested incompatibilities c c++ reduced much possible order maximize inter-operability two languages others argued since c c++ two different languages compatibility useful vital according camp efforts reduce incompatibility hinder attempts improve language isolation official rationale 1999 c standard c99 endorse nowiki /nowiki principle maintaining largest common subset c c++ maintaining distinction allowing evolve separately stated authors content let c++ big ambitious language several additions c99 supported current c++ standard conflicted c++ features variable-length arrays native complex number types codice_1 type qualifier hand c99 reduced incompatibilities compared c89 incorporating c++ features codice_2 comments mixed declarations code c++ enforces stricter typing rules implicit violations static type system initialization requirements compile-time enforcement in-scope variables initialization subverted c valid c code disallowed c++ rationale provided annex c.1 iso c++ standard though c++ favors c99 c11 added several additional features c incorporated standard c++ complex numbers variable length arrays note complex numbers variable length arrays designated optional extensions c11 flexible array members restrict keyword array parameter qualifiers compound literals designated initializers c++ adds numerous additional keywords support new features renders c code using keywords identifiers invalid c++ example syntactical constructs valid c c++ produce different results two languages several differences previous section also exploited create code compiles languages behaves differently example following function return different values c c++ due c requiring codice_15 front structure tags codice_60 refers variable c++ allowing omitted codice_60 refers implicit codice_62 beware outcome different codice_44 declaration placed inside function presence identifier name function scope inhibits implicit codice_62 take effect c++ outcome c c++ would observe also ambiguity example due use parenthesis codice_65 operator using codice_66 would expect codice_67 expression type thus example would compile c++ c c++ maintain large degree source compatibility object files respective compilers produce important differences manifest intermixing c c++ code notably reasons c++ code call c function codice_68 c++ code must prototype codice_68 codice_70 likewise c code call c++ function codice_71 c++ code codice_71 must declared codice_70 common practice header files maintain c c++ compatibility make declaration codice_70 scope header differences c c++ linkage calling conventions also subtle implications code uses function pointers compilers produce non-working code function pointer declared codice_70 points c++ function declared codice_70 example following code using sun microsystems c++ compiler produces following warning codice_77 declared c linkage calling conventions passed c function codice_68
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Programming language topics
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enhanced write filter enhanced write filter ewf component windows xp embedded windows embedded standard 7 stores volume changes another medium instead applying original volume ewf allows writes discarded committed original volume later either directly inaction based configuration minimizes writes specified hard disk ewf fbwf file-based write filter become popular enthusiast computing way decreasing wear solid-state drives netbooks carpcs ewf three main operating modes ewf disk ewf ram ewf ram reg mode location ewf volume stores configuration overlay volume stores file changes different ewf disk stores overlay data outside primary disk allowing external disk compactflash used overlay ewf volume stored unpartitioned space disk ewf ram stores overlay data ram ewf volume unpartitioned space disk ewf ram reg ewf ram except ewf volume stored windows registry case appropriation ewf carpcs often based windows xp smaller footprint used similar effect windows vista netbooks diminish write activity enhance lifespan solid state drives due changes windows vista however disk mode used unlike commercial ram disks ewf reclaim ram files deleted ewf ram ewf ram reg mode memory consumed ever increases eventually system free space crash automatic adjustment daylight saving time compatible ewf causing incorrect time settings reboot
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Operating systems
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webtrekk webtrekk gmbh german company offers marketing analytics customer intelligence software webtrekk companies connect analyze activate user marketing data across devices since 2019 webtrekk part marketing technology service provider mapp webtrekk founded 2004 ceo christian sauer cto norman wahnschaff 2009 webtrekk received €1 million venture capital investment corporate finance partners winners awin-sponsored publisher initiative contest 2012 webtrekk frost sullivan award finally bringing ‘ real time ’ online/digital analytics 2014 webtrekk closed third round financing collecting total €25 million dpe deutsche private equity 2018 webtrekk bronze international stevie award category business competitive intelligence “ cross device tracking tool cross device bridge 2019 webtrekk honored german stevie award gold realtime predictions 2019 webtrekk acquired marketing technology service provider mapp webtrekk provides variety products gain insights data trigger marketing activities products services cross-channel campaign reporting ai-enabled marketing intelligence webtrekk customer analytics suite includes user-centric analytics personalized product recommendations customer intelligence dashboards customer journey tracking tag integration web behavior re-targeting webtrekk data streams enable raw data captured processed streamed real time since acquisition webtrekk mapp consolidate offerings webtrekk ’ customers also access mapp ’ cross-channel marketing cloud consulting support another part webtrekk offering consulting unit works customers specific large-scale projects support team available answer questions functions interface webtrekk products access raw first-party data core component webtrekk products data exported real-time data warehouses bi systems used carry in-depth analyses within customer analytics suite suite customizable dashboard engine enables customers display connected external data sources social media channels crm systems webtrekk 400 customers including flixbus ing mytoys focus industries finance publishing e-commerce products privacy certified german tüv association confirm data privacy security webtrekk ’ data servers located european union housed data centres certified international organization standardization
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Web technology
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norton antivirus norton antivirus anti-virus anti-malware software product developed distributed symantec corporation since 1991 part norton family computer security products uses signatures heuristics identify viruses features included e-mail spam filtering phishing protection symantec distributes product download box copy oem software norton antivirus norton internet security related product held 61 us retail market share security suites first half 2007 competitors terms market share study include antivirus products ca trend micro kaspersky lab norton antivirus runs microsoft windows linux macos windows 7 support development versions 2006 2008 version 2009 windows 7 supported update already versions 2010 2011 2012 natively support windows 7 without needing update version 12 version fully compatible mac os x lion 2015 series products symantec made changes portfolio briefly discontinued norton antivirus action later reversed introduction norton antivirus basic may 1989 symantec launched symantec antivirus macintosh sam sam 2.0 released march 1990 incorporated technology allowing users easily update sam intercept eliminate new viruses including many n't exist time program release august 1990 symantec acquired peter norton computing peter norton norton company developed various dos utilities including norton utilities include antivirus features symantec continued development acquired technologies technologies marketed name norton tagline symantec norton crossed-arm pose registered u.s. trademark traditionally featured norton product packaging however pose later moved spine packaging eventually dropped altogether early 1991 u.s. computers invaded hundreds foreign virus strains corporate pc infection becoming serious problem symantec norton group launched norton antivirus 1.0 nav pc compatible computers ads product suggested retail 129 featured norton crossed-arm pose wearing pink shirt surgical mask covering nose mouth 1998 version 5.0 update sam renamed norton antivirus nav macintosh product activation introduced norton antivirus 2004 addressing estimated 3.6 million counterfeit norton products sold alphanumeric code generated identify computer configuration ties product key users allowed activate product five times product key spyware adware detection removal introduced 2005 version tagline antispyware edition tagline dropped later releases however norton antivirus 2009 classic include spyware adware detection classic edition marketed alongside norton antivirus 2009 include spyware adware detection existing users 2006 2007 2008 2009 versions upgrade latest 2010 version without buying new subscription upgrading preserve number days left user subscription redesigned main graphical user interface aggregates information central user interface cnet reports norton protection center useful attempts advertise additional products facilitate detection zero-day malware bloodhound disassembles variety programming languages scans code malicious instructions using predefined algorithms internet explorer homepage hijacking protection introduced release well however notably missing search engine hijacking protection cnet highlighted norton antivirus 2006 noticeable impact system performance operating system requirements call windows 2000 service pack 3 windows xp 150 mb free space 300 mhz processor required either operating system 128 mb ram required windows 2000 256 mb required windows xp norton antivirus released september 12 2006 symantec revised norton antivirus goal reducing high system resource utilization windows vista compatibility introduced release well despite 80 code rewritten cnet reports mixed results performance testing windows 2000 compatibility dropped release compatibility 32-bit versions windows vista added release patch symantec hardware requirements vista call 150 mb free space 800 mhz processor 512 mb ram requirements windows xp similarly call 150 mb free space 300 mhz processor 256 mb ram norton antivirus 2008 released august 28 2007 emphasizing malware prevention new features include sonar looks suspicious application behavior release adds real-time exploit protection preventing attackers leveraging common browser application vulnerabilities installed 32-bit versions windows xp service pack 2 300 mb free space 300 mhz processor 256 mb ram required installed 32-bit 64-bit versions windows vista 300 mb free space 800 mhz processor 256 mb ram needed norton antivirus 2009 released september 8 2008 addressing performance issues 300 changes made zero-impact goal.benchmarking conducted passmark software pty ltd highlights 47-second install time 32 second scan time 5 mb memory utilization symantec funded benchmark test provided scripts used benchmark participating antivirus software security status settings displayed single main interface cpu usage monitor displays total cpu utilization norton cpu usage main interface features include norton insight whitelisting technology cuts scanning times mapping known safe files using information online database address malware response times updates delivered every 5 15 minutes however updates tested symantec may cause false positives incorrectly identify files malicious exploit scanner found 2007 2008 versions dropped release installed 32-bit versions windows xp service pack 2 150 mb free space 300 mhz processor 256 mb ram required installed 32-bit 64-bit versions windows vista 150 mb free space 800 mhz processor 512 mb ram required two variations norton antivirus 2009 also marketed symantec gaming edition provides finer control norton downloads updates allows components suite disabled either manually automatically computer enters full-screen mode classic edition find remove adware spyware version 17.0 released september 9 2009 several features updated release including sonar dubbed sonar 2 uses information determine application truly malicious norton insight present users information origins activities performance applications along reputation data new feature codenamed autospy helps users understand norton malware found previous releases removed threats sight quietly warned users potentially confusing users deceived downloading rogue security software much information placed back main window toggle button switches sides symantec also added windows 7 support aside symantec also added norton download insight prevent drive drive downloads symantec briefly discontinued standalone norton antivirus product 2015 instead replacing norton security fbi confirmed active development magic lantern keylogger intended obtain passwords encrypted e-mail documents criminal investigations magic lantern first reported media bob sullivan msnbc 20 november 2001 ted bridis associated press fbi intends deploy magic lantern form e-mail attachment attachment opened installs trojan horse suspect computer activated suspect uses pgp encryption often used increase security sent email messages activated trojan log pgp password allows fbi decrypt user communications symantec major antivirus vendors whitelisted magic lantern trojan rendering antivirus products including norton antivirus incapable detecting concerns around whitelisting include uncertainties magic lantern full surveillance potential whether hackers could subvert redeploy purposes outside law enforcement graham cluley technology consultant sophos said way knowing written fbi even ’ know whether used fbi commandeered third party another reaction came marc maiffret chief technology officer co-founder eeye digital security states customers paying us service protect forms malicious code us law enforcement job make exceptions law enforcement malware tools proponents magic lantern argue technology would allow law enforcement efficiently quickly decrypt time-sensitive messages protected encryption schemes implementing magic lantern require physical access suspect computer unlike carnivore predecessor magic lantern since physical access computer would require court order fbi spokesman paul bresson response question whether magic lantern also needed court order deploy would say like technology projects tools deployed fbi would used pursuant appropriate legal process january 28 2010 symantec anti-virus update marked spotify trojan horse disabling software across millions pcs retail customers report slow indifferent service bugs examples include faulty error message stating current subscriptions expired users received error stating virus protection updated error occurred update software refused allow daily updates though bug reported 2004 corrected 2005 2006 versions another incident occurred may 2007 norton antivirus flagged components pegasus email client malicious rendering program corrupted symantec customer service addressed problem running checklist troubleshooting steps always successful july 25 2006 symantec released faulty update norton antivirus 2006 users users reported onscreen message stating norton antivirus 2006 support repair feature please uninstall reinstall. symantec claimed faulty update downloaded customers 1:00 pm 7:00 pm july 25 2006 symantec developed workaround tool listed troubleshooting steps available company released statement stating expected deliver repair patch affected users monday july 31 2006 norton antivirus criticized refusing uninstall completely leaving unnecessary files behind another issue versions prior 2009 installed liveupdate updates norton-branded software separately user must uninstall norton antivirus liveupdate component manually liveupdate component purposely left behind update norton-branded products present response symantec developed norton removal tool symnrt remove leftover registry keys values along files folders however neither route uninstallation remove subscription data preserved prevent users installing multiple trial copies symnrt remove norton programs symnrt started removal process stopped recommended close running programs prior running symnrt act winfax users recommended back databases running symnrt norton antivirus 2007 install alongside zonealarm incompatibility caused annoyance norton customers purchased norton antivirus 2007 prior warning notice incompatibility symantec recommends removing zonealarm reinstalling internet worm protection feature disabled controls applications access internet protocols use march 9 2009 users norton antivirus 2006 2007 experienced firewall warning stating norton-associated file pifts.exe trying connect internet although file revealed harmless diagnostic patch program gained attention media symantec removed posts forum concerning pifts information available purpose program speculation program malware backdoor sans internet storm center claimed spoken symantec employee confirmed program part update process intended harm graham cluley consultant antivirus vendor sophos found pifts connected symantec server forwarding product computer information march 10 symantec made official response pifts program claiming posts support forum deleted due forum spam rules however deletion pifts-related posts began spam attacks symantec stated pifts diagnostic patch cole stated purpose update help determine many customers would need migrated windows 7-compatible versions norton antivirus pifts apparently released without digital signature verify identity causing firewalls prompt permission attempted connect internet symantec criticized consumers perceived ethical violations including allegations support technicians would tell customers systems infected needed technician resolve remotely extra fee refuse refund customers alleged systems actually infected norton antivirus 11 mac introduced support mac os x v10.5 leopard platform capability detect macintosh windows malware features include vulnerability scanner blocks attackers leveraging software exploits norton antivirus 11 also includes ability scan within compressed archived files time capsule volumes operating requirements call mac os x tiger powerpc intel core processor 128 mb ram 100 mb free hard disk space also required norton antivirus dual protection mac intended macintosh users windows running systems using boot camp virtualization software vmware fusion provides license norton antivirus 11 norton antivirus 2009 2009 2012 editions symantec made huge changes products speed performance norton products 2 running processes using 24 mb ram soon virus recognized information regards virus virus signature stored pandemic definitions file contains vital know-how become aware get rid virus according tests sponsored symantec passmark security benchmark 2012 norton antivirus norton internet security lightest suites available av-comparatives.org also tested products gave similar results pcmag recognises 2011 2012 lines fastest strongest protection pcworld tests security software put norton internet security 2009 1st place 2011 test pcworld norton internet security winner dennis technology labs tests sponsored symantec confirms performance effectiveness norton 2011 2012 lines 14th august 2013 prime minister new zealand john key addressed identified misinformation surrounding gcsb amendment bill claiming actions government communications security bureau analogous norton antivirus
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Computer security
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evil maid attack evil maid attack attack unattended device attacker physical access alters undetectable way later access device data name refers scenario maid could subvert device left unattended hotel room – concept also applies situations device intercepted transit taken away temporarily airport law enforcement personnel 2009 blog post security analyst joanna rutkowska coined term evil maid attack due hotel rooms common place devices left unattended post detailed method compromising firmware unattended computer via external usb flash drive – therefore bypassing truecrypt disk encryption d. defreez computer security professional first mentioned possibility evil maid attack android smartphones 2011 talked whispercore android distribution ability provide disk encryption androids 2007 former u.s. commerce secretary carlos gutierrez allegedly targeted evil maid attack business trip china left computer unattended trade talk beijing suspected device compromised although allegations yet confirmed denied incident caused u.s. government wary physical attacks 2009 symantec cto mark bregman advised several u.s. agencies leave devices u.s. travelling china instructed buy new ones leaving dispose returned physical attempts retrieve data would ineffective attack begins victim leaves device unattended attacker proceed tamper system victim password protection authentication computer intruder turn computer immediately access victim information however device password protected full disk encryption firmware device needs compromised usually done external drive compromised firmware often provides victim fake password prompt identical original password input compromised firmware sends password attacker removes reboot order successfully complete attack attacker must return device unattended second time steal now-accessible data another method attack dma attack attacker accesses victim information hardware devices connect directly physical address space attacker simply needs connect hardware device order access information evil maid attack also done replacing victim device identical device original device bootloader password attacker needs acquire device identical bootloader password input screen device lock screen however process becomes difficult attacker must acquire background picture put lock screen mimicking device either case victim inputs password false device device sends password attacker possession original device attacker access victim data legacy bios considered insecure evil maid attacks architecture old updates option roms unsigned configuration unprotected additionally support secure boot vulnerabilities allow attacker boot external drive compromise firmware compromised firmware configured send keystrokes attacker remotely unified extensible firmware interface uefi provides many necessary features mitigating evil maid attacks example offers framework secure boot authenticated variables boot-time tpm initialization security despite available security measures platform manufacturers obligated use thus security issues may arise unused features allow attacker exploit device many full disk encryption systems truecrypt pgp whole disk encryption susceptible evil maid attacks due inability authenticate user attacker still modify disk contents despite device powered encrypted attacker modify encryption system loader codes steal passwords victim unattended device vulnerable network evil maid attack attacker knows victim device well enough replace victim device identical model password-stealing mechanism thus victim inputs password attacker instantly notified able access stolen device information one approach detect someone close handling unattended device proximity alarms motion detector alarms wireless cameras used alert victim attacker nearby device thereby nullifying surprise factor evil maid attack android app created 2017 edward snowden monitoring transmit results user smartphone absence tamper-evident technology various kinds used detect whether device taken apart – including low-cost solution putting glitter screw holes attack suspected victim device checked see malware installed challenging suggested approaches checking hashes selected disk sectors partitions device surveillance times attacker perform evil maid attack left unattended device may also placed inside lockbox attacker physical access however situations device taken away temporarily airport law enforcement personnel practical basic security measures latest up-to-date firmware shutting device leaving unattended prevent attack exploiting vulnerabilities legacy architecture allowing external devices open ports respectively cpu-based disk encryption systems tresor loop-amnesia prevent data vulnerable dma attack ensuring leak system memory tpm-based secure boot shown mitigate evil maid attacks authenticating device user unlocking correct password given user measures unauthorized code executed device measurements done root trust systems microsoft bitlocker intel txt technology anti evil maid program builds upon tpm-based secure boot attempts authenticate device user
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Computer security
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national initiative cybersecurity education national initiative cybersecurity education nice partnership government academia private sector focused supporting country ability address current future cybersecurity education workforce challenges standards best practices nice led national institute standards technology nist u.s. department commerce comprehensive national cybersecurity initiative cnci established president george w. bush january 2008 included twelve initiatives one initiative 8 aimed making federal cybersecurity workforce better prepared handle cybersecurity challenges may 2009 cyberspace policy review directed president barack obama elevated cnci initiative 8 initially focused improving federal cybersecurity workforce ability perform cybersecurity work scope expanded beyond federal workforce include private sector workforce truly making national charge march 2010 obama administration declassified limited material regarding cnci making initiative 8 public initiative 8 expand cyber education billions dollars spent new technologies secure u.s. government cyberspace people right knowledge skills abilities implement technologies determine success however enough cybersecurity experts within federal government private sector implement cnci adequately established federal cybersecurity career field existing cybersecurity training personnel development programs good limited focus lack unity effort order effectively ensure continued technical advantage future cybersecurity must develop technologically-skilled cyber-savvy workforce effective pipeline future employees take national strategy similar effort upgrade science mathematics education 1950 ’ meet challenge additionally cnci described training education professional development programs lacking “ unity effort ” cybersecurity enhancement act 2014 title iv established “ national cybersecurity awareness education program ” known national initiative cybersecurity education nice digital economy enabled knowledgeable skilled cybersecurity workforce energize promote robust network ecosystem cybersecurity education training workforce development nice cybersecurity workforce framework nice cybersecurity workforce framework nice framework nist special publication 800-181 national focused resource categorizes describes cybersecurity work publication serves fundamental reference support workforce capable meeting organization cybersecurity needs establishing taxonomy common lexicon describes cybersecurity work workers irrespective work performed nice framework intended applied public private academic sectors although nice framework published nist special publication august 2017 working drafts document use since 2010 publication intended living document updated periodically based change requests nice program office plethora tools resources exist learning implementing nice framework learn nist.gov/nice/framework nice strategic plan cybersecurity enhancement act 2014 requires strategic plan developed implemented every five years current nice strategic plan includes multitude guiding values three primary goals 1 accelerate learning skills development 2 nurture diverse learning community 3 guide career planning workforce development see current past versions nice strategic plan nist.gov/nice supporting growth sustainment nation cybersecurity workforce building foundation secure american future may 2017 president donald trump issued executive order strengthening cybersecurity federal networks critical infrastructure part order states policy united states “ support growth sustainment workforce skilled cybersecurity related fields foundation achieving objectives cyberspace. ” consequently secretary commerce secretary homeland security directed provide report president findings recommendations regarding support growth sustainment nation cybersecurity workforce public private sectors report supporting growth sustainment nation cybersecurity workforce building foundation secure american future response charge nice framework work role capability indicators indicators performing work roles nice framework work role capability indicators indicators performing work roles draft nist interagency report 8193 co-authored representatives u.s. department homeland security national institute standards technology booz allen hamilton inc document helps determine qualities accomplishments indicate someone suitable perform particular job activity qualities defined report “ capability indicators. ” nice headquartered nist facilities gaithersburg maryland nice program office activities organized three categories government engagement industry engagement academic engagement committees nice several committees nice challenge project nice challenge project led california state university san bernardino designed create flexible set challenge environments supporting infrastructure low barrier use one would able perform tasks outlined nice cybersecurity workforce framework used platform instruction well evaluate endeavor part cybersecurity workforce cyberseek cyberseek interactive heat map pathway tool developed comptia partnership burning glass technologies provides data visualization need supply cybersecurity workers guide employers job seekers policy makers education training providers guidance counselors cyberseek includes cybersecurity jobs heat map shows information supply workers relevant credentials project also shows career pathways cybersecurity map opportunities advancement field regional alliances multistakeholder partnerships stimulate cybersecurity education workforce development ramps ramps program provides funding opportunities build multistakeholder workforce partnerships employers schools institutions higher education community organizations
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Computer security
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keyraider keyraider computer malware affects jailbroken apple ios devices specifically iphones allows criminals steal users login password information well lock devices demand ransom unlock discovered researchers palo alto networks weiphone august 2015 believed led 225,000 people login password information stolen making according cybersecurity columnist joseph steinberg one damaging pieces malware ever discovered apple universe malware originally found chinese website spread 18 countries including united states keyraider affects iphones jailbroken
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Computer security
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docs software docs display operator console support software package ibm mainframes cfs inc. enabling access system console using 3270-compatible terminals computer operators communicated ibm mainframe computers using electro-mechanical typewriter-like console came standard ibm 360 370 computer except upper end models offered video consoles model 20 came standard without console majority smaller less expensive ibm 360s 370s came equipped ruggedized selectric keyboard devices selectric major step teletypes tty associated unix smaller systems still clunky video consoles provided certain models considered particularly user friendly ignored two thirds ibm mainframe market dos vse descendants docs replaced supplanted typewriter interface video screen practice worked little like present-day instant messenger programs icq qq aim adium ichat etc data entry line bottom messages scrolling real time screen commands otherwise identical docs available dos dos/vs dos/vse came packaged third party operating systems edos computer software company later acquired nixdorf product ran several dos-related platforms several vendors offered docs part os docs developed cfs inc. brookline massachusetts kayser-roth data center whitman massachusetts dick goran wrote video interface leigh lundin wrote operating system interface transcript recorder docs required dedicated partition dos three partitions dos/vs seven giving partition docs placed crimp practicability leigh lundin designed fx pseudo-partition relieved user relinquishing working partition fx appeared dos/vs version sdi grasp f0 docs sold north america cfs inc brookline overseas sales cfs engaged mail order local vendors product also embedded third party operating system packages edos vdos
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Operating systems
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uk cyber security community cyber security information assurance community united kingdom diverse many stakeholders groups contributing support uk cyber security strategy following list stakeholders according parliamentary committee uk government enough protect nation cyber attack cyber aware cross-government awareness behaviour campaign provides advice simple measures individuals take protect cyber crime department digital culture media sport one lead government departments cyber security policy responsible supporting promoting uk cyber security sector promoting cyber security research innovation working national cyber security centre help ensure uk organisations secure online resilient cyber threats get safe online united kingdom-based campaign national initiative teach citizens basic computer security internet privacy national crime agency nca hosts law enforcement cyber crime unit incorporating child exploitation online protection centre national cyber security centre uk ’ authority cyber security parent organisation gchq absorbed replaced cesg information security arm gchq well centre cyber assessment cca computer emergency response team uk cert uk cyber-related responsibilities centre protection national infrastructure cpni ncsc provides advice support public private sector avoid cyber threats cesg originally communications-electronics security group branch gchq worked secure communications information systems government critical parts uk national infrastructure centre protection national infrastructure cpni provided protective security advice businesses organisations across national infrastructure national security council cabinet committee tasked overseeing issues related national security intelligence coordination defence strategy office cyber security information assurance ocsia supports minister cabinet office rt hon francis maude mp national security council determining priorities relation securing cyberspace unit provides strategic direction coordinates action relating enhancing cyber security information assurance uk ocsia headed james quinault trustworthy software initiative tsi uk public good activity sponsored uk government centre protection national infrastructure aimed 'making software better warning advice reporting points warps provide trusted environment members community share problems solutions uk cyber security forum social enterprise representing cyber sme small medium enterprise uk forum composed 20 regional cyber clusters around uk cluster run subsidiary uk cyber security forum operated groups volunteers provide events around uk engage public cyber security provide continued professional development cyber professionals official clusters ads trade organisation companies operating uk aerospace defence security space industries business continuity institute bci established 1994 enable individual members obtain guidance support fellow business continuity practitioners profit accreditation certification organisation cdf promotes global interests uk crypto development industry information assurance advisory council iaac works across industry government academia towards ensuring uk ’ information society robust resilient secure foundation iaac set baroness neville-jones chaired organisation 2007 handing current chairman sir edmund burton affiliates include bt group northrop grumman qinetiq raytheon pwc o2 uk ultra electronics glaxosmithkline 2012/13 work programme focused consumerisation effects information assurance iacg formed following uk national ia conference 2006 iacg encourages greater collaboration commercial supply base information assurance products services operating within uk public sector stakeholders include cesg bis office cyber security information assurance ocsia cyber security operations centre csoc cpni group maintains uk information assurance community map hosted cesg web site two co-chairs colin robbins nexor ross parsell thales iacg ceased operation 2014 information systems security association issa not-for-profit international professional organization information security professionals practitioners uk chapter institute information security professionals iisp independent non-profit body governed members principal objective advancing professionalism information security practitioners thereby professionalism industry whole isaca international professional association deals governance previously known information systems audit control association isc ² international information systems security certification consortium non-profit organization specializes information security education certifications ndi former government-funded organisation building supply chains mod manufacturers using smes united kingdom techuk formerly known intellect uk trade association technology industry cyber security group focused “ high threat ” areas – including defence national security resilience protection critical national infrastructure intelligence organised crime chaired dr andrew rogoyski roke manor research security resilience group works build strong relationships technology industry policymakers customers end users chaired stephen kingan nexor tigerscheme commercial certification scheme technical security specialists backed university standards covering wide range expertise tigerscheme cesg certified uk candidates subject independent rigorous academic assessment authority tigerscheme founded 2007 principle commercial certification scheme run independent lines would give buyers security testing services confidence hiring recognised reputable company june 2014 operational authority tigerscheme transferred usw commercial services ltd. ukceb not-for-profit membership organisation whose mission transform secure information sharing life collaboration defence acquisition support british computer society bcs professional body learned society represents working information technology united kingdom internationally security data privacy group cyber scheme profit professional examination body contract national cyber security centre provide technical exams support governments assured penetration testing company scheme check exams independent rigorous conducted practitioner team member level team leader levels gchq accredited several academic centres excellence cyber security research accreditations expire july 2017 results re-accreditation process expected mid february 2017 information security research group isrg university south wales multidisciplinary team academics industrial experts focusing upon cyber security particular group focusing upon cyber security centre csc de montfort university multidisciplinary group academics focus wide variety cyber security digital forensics issues centre mission provide full benefits safe secure resilient cyberspace
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Computer security
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link control protocol computer networking link control protocol lcp forms part point-to-point protocol ppp within family internet protocols setting ppp communications sending receiving devices send lcp packets determine standards ensuing data transmission lcp protocol devices use ppp transmit data network lcp packet determines acceptability link lcp packets embedded ppp packets therefore basic ppp connection established lcp reconfigure lcp ppp packets control code 0xc021 info field contains lcp packet four fields code id length data
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Internet protocols
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registered port registered port network port sub-address defined within internet protocol range 1024–49151 assigned internet assigned numbers authority iana internet corporation assigned names numbers icann march 21 2001 usc/isi 1998 use certain protocol application ports numbers 0–1023 called system well-known ports ports numbers 1024-49151 called user registered ports ports numbers 49152-65535 called dynamic and/or private ports system user ports used transport protocols tcp udp dccp sctp indicate application service
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Internet protocols
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lightweight directory access protocol lightweight directory access protocol ldap open vendor-neutral industry standard application protocol accessing maintaining distributed directory information services internet protocol ip network directory services play important role developing intranet internet applications allowing sharing information users systems networks services applications throughout network examples directory services may provide organized set records often hierarchical structure corporate email directory similarly telephone directory list subscribers address phone number ldap specified series internet engineering task force ietf standard track publications called request comments rfcs using description language asn.1 latest specification version 3 published rfc 4511 road map technical specifications provided rfc4510 common use ldap provide central place store usernames passwords allows many different applications services connect ldap server validate users ldap based simpler subset standards contained within x.500 standard relationship ldap sometimes called x.500-lite telecommunication companies understanding directory requirements well developed 70 years producing managing telephone directories companies introduced concept directory services information technology computer networking input culminating comprehensive x.500 specification suite protocols produced international telecommunication union itu 1980s x.500 directory services traditionally accessed via x.500 directory access protocol dap required open systems interconnection osi protocol stack ldap originally intended lightweight alternative protocol accessing x.500 directory services simpler widespread tcp/ip protocol stack model directory access borrowed dixie directory assistance service protocols protocol originally created tim howes university michigan steve kille isode limited colin robbins nexor wengyik yeong performance systems international circa 1993 successor dixie das mark wahl critical angle inc. tim howes steve kille started work 1996 new version ldap ldapv3 aegis internet engineering task force ietf ldapv3 first published 1997 superseded ldapv2 added support extensibility integrated simple authentication security layer better aligned protocol 1993 edition x.500 development ldapv3 specifications numerous extensions adding features ldapv3 come ietf early engineering stages ldap known lightweight directory browsing protocol ldbp renamed expansion scope protocol beyond directory browsing searching include directory update functions given lightweight name network intensive dap predecessor thus easily implemented internet due relatively modest bandwidth usage ldap influenced subsequent internet protocols including later versions x.500 xml enabled directory xed directory service markup language dsml service provisioning markup language spml service location protocol slp also used basis microsoft active directory client starts ldap session connecting ldap server called directory system agent dsa default tcp udp port 389 port 636 ldaps ldap ssl see client sends operation request server server sends responses return exceptions client need wait response sending next request server may send responses order information transmitted using basic encoding rules ber client may request following operations addition server may send unsolicited notifications responses request e.g connection timed common alternative method securing ldap communication using ssl tunnel default port ldap ssl 636 use ldap ssl common ldap version 2 ldapv2 never standardized formal specification usage deprecated along ldapv2 officially retired 2003 global catalog available default ports 3268 3269 ldaps protocol provides interface directories follow 1993 edition x.500 model dn may change lifetime entry instance entries moved within tree reliably unambiguously identify entries uuid might provided set entry operational attributes entry look like represented ldap data interchange format ldif ldap binary protocol codice_3 distinguished name entry neither attribute part entry codice_4 entry rdn relative distinguished name codice_5 dn parent entry codice_6 denotes 'domain component lines show attributes entry attribute names typically mnemonic strings like codice_7 common name codice_6 domain component codice_9 e-mail address codice_10 surname server holds subtree starting specific entry e.g codice_5 children servers may also hold references servers attempt access codice_12 could return referral continuation reference server holds part directory tree client contact server servers also support chaining means server contacts server returns results client ldap rarely defines ordering server may return values attribute attributes entry entries found search operation order follows formal definitions entry defined set attributes attribute set values sets need ordered add operation inserts new entry directory-server database distinguished name add request already exists directory server add duplicate entry set result code add result decimal 68 entryalreadyexists example codice_13 must exist codice_14 must exist ldap session created ldap client connects server authentication state session set anonymous bind operation establishes authentication state session simple bind sasl plain send user dn password plaintext connections utilizing either simple sasl plain encrypted using transport layer security tls server typically checks password codice_15 attribute named entry anonymous bind empty dn password resets connection anonymous state sasl simple authentication security layer bind provides authentication services wide range mechanisms e.g kerberos client certificate sent tls bind also sets ldap protocol version sending version number form integer client requests version server support server must set result code bind response code protocol error normally clients use ldapv3 default protocol always ldap libraries bind first operation session ldapv2 required ldapv3 ldapv3 successful bind request changes authentication state session unsuccessful bind request resets authentication state session delete entry ldap client transmits properly formed delete request server search operation used search read entries parameters server returns matching entries potentially continuation references may returned order final result include result code compare operation takes dn attribute name attribute value checks named entry contains attribute value modify operation used ldap clients request ldap server make changes existing entries attempts modify entries exist fail modify requests subject access controls implemented server modify operation requires distinguished name dn entry specified sequence changes change sequence must one ldif example adding value attribute replace value existing attribute use replace keyword attribute multi-valued client must specify value attribute update delete attribute entry use keyword delete changetype designator modify attribute multi-valued client must specify value attribute delete also modify-increment extension allows incrementable attribute value incremented specified amount following example using ldif increments employeenumber 5 ldap servers replicated topology ldap clients consider using post-read control verify updates instead search update post-read control designed applications need issue search request update – bad form retrieve entry sole purpose checking update worked replication eventual consistency model ldap client assume connects directory server request architects may placed load-balancers ldap proxies ldap clients servers modify dn move/rename entry takes new rdn relative distinguished name optionally new parent dn flag indicates whether delete value entry match old rdn server may support renaming entire directory subtrees update operation atomic operations see either new entry old one hand ldap define transactions multiple operations read entry modify another client may updated entry meantime servers may implement extensions support though extended operation generic ldap operation define new operations part original protocol specification starttls one significant extensions examples include cancel password modify starttls operation establishes transport layer security descendant ssl connection provide data confidentiality protect data observed third parties and/or data integrity protection protects data tampering tls negotiation server sends x.509 certificate prove identity client may also send certificate prove identity client may use sasl/external using sasl/external client requests server derive identity credentials provided lower level tls though technically server may use identity information established lower level typically server use identity information established tls servers also often support non-standard ldaps secure ldap commonly known ldap ssl protocol separate port default 636 ldaps differs ldap two ways 1 upon connect client server establish tls ldap messages transferred without starttls operation 2 ldaps connection must closed upon tls closure ldaps client libraries encrypt communication check host name name supplied certificate abandon operation requests server abort operation named message id server need honor request neither abandon successfully abandoned operation send response similar cancel extended operation send responses implementations support unbind operation abandons outstanding operations closes connection response name historical origin opposite bind operation clients abort session simply closing connection use unbind unbind allows server gracefully close connection free resources would otherwise keep time discovering client abandoned connection also instructs server cancel operations canceled send responses operations canceled ldap uniform resource identifier uri scheme exists clients support varying degrees servers return referrals continuation references see rfc 4516 components described optional example codice_28 refers user attributes john doe entry codice_29 codice_30 searches entry default server note triple slash omitting host double question mark omitting attributes urls special characters must percent-encoded similar non-standard codice_31 uri scheme ldap ssl confused ldap tls achieved using starttls operation using standard codice_32 scheme contents entries subtree governed directory schema set definitions constraints concerning structure directory information tree dit schema directory server defines set rules govern kinds information server hold number elements including attributes elements responsible storing information directory schema defines rules attributes may used entry kinds values attributes may clients may interact values clients may learn schema elements server supports retrieving appropriate subschema subentry schema defines object classes entry must objectclass attribute containing named classes defined schema schema definition classes entry defines kind object entry may represent e.g person organization domain object class definitions also define list attributes must contain values list attributes may contain values example entry representing person might belong classes top person membership person class would require entry contain sn cn attributes allow entry also contain userpassword telephonenumber attributes since entries may multiple objectclasses values entry complex optional mandatory attribute sets formed union object classes represents objectclasses inherited single entry multiple objectclasses values define available required attributes entry parallel schema objectclass class definition instance object-oriented programming representing ldap objectclass ldap entry respectively directory servers may publish directory schema controlling entry base dn given entry subschemasubentry operational attribute operational attribute describes operation directory rather user information returned search explicitly requested server administrators add additional schema entries addition provided schema elements schema representing individual people within organizations termed white pages schema lot server operation left implementor administrator decide accordingly servers may set support wide variety scenarios example data storage server specified server may use flat files databases gateway server access control standardized though work commonly used models users passwords may stored entries elsewhere server may refuse perform operations wishes impose various limits parts ldap extensible examples one define new operations controls may modify requests responses e.g request sorted search results new search scopes bind methods defined attributes options may modify semantics ldap gained momentum vendors provided access protocol services implementation recasts data mimic ldap/x.500 model closely model followed varies example software access sql databases ldap even though ldap readily lend x.500 servers may support ldap well similarly data previously held types data stores sometimes moved ldap directories example unix user group information stored ldap accessed via pam nss modules ldap often used services authentication and/or authorization actions given already-authenticated user service example active directory kerberos used authentication step ldap used authorization step example data model glue schema used distributed information system based ldap enable users applications services discover services exist grid infrastructure information structure state ldap server may return referrals servers requests fulfill requires naming structure ldap entries one find server holding given distinguished name dn concept defined x.500 directory also used ldap another way locating ldap servers organization dns server record srv organization domain example.org may use top level ldap dn codice_33 dc means domain component ldap server also named ldap.example.org organization top level ldap url becomes codice_34 primarily two common styles naming used x.500 2008 ldapv3 documented itu specifications ietf rfcs original form takes top level object country object codice_35 codice_36 domain component model uses model described example country based naming could codice_37 us codice_38
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Internet protocols
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multiprogramming system multiprogramming system os computer operating system designed team led edsger w. dijkstra described monographs 1965-66 published 1968 dijkstra never named system simply abbreviation technische hogeschool eindhoven name dutch eindhoven university technology netherlands system primarily batch system supported multitasking designed multi-user operating system much like sds 940 set processes system static system apparently introduced first forms software-based paged virtual memory electrologica x8 support hardware-based memory management freeing programmers forced use actual physical locations drum memory using modified algol compiler programming language supported dijkstra system automatically generate calls system routines made sure requested information memory swapping necessary paged virtual memory also used buffering i/o device data significant portion operating system code well nearly algol 60 compiler system semaphores used programming construct first time design multiprogramming system significant use layered structure higher layers depend lower layers constraint higher layers depend lower layers imposed designers order make reasoning system using quasi-formal methods tractable also facilitate building testing system incrementally layers implemented order layer 0 first thorough testing abstractions provided layer turn division kernel layers similar ways multics later ring-segmentation model several subsequent operating systems used layering extent including windows nt macos although usually fewer layers code system written assembly language dutch electrologica x8 computer computer word size 27 bits 32 kilowords core memory 512 kilowords drum memory providing backing store lru cache algorithm paper tape readers paper tape punches plotters printers
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Operating systems
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