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jeffrey carney jeffrey martin carney former united states air force intelligence specialist convicted spying east german ministry state security mfs stasi one stasi successful spies code-named kid uwe carney became alienated angry u.s. air force u.s. policies president ronald reagan began handing u.s. military documents stasi working west berlin u.s. air force transfer back goodfellow air force base 1984 carney decided request permanent asylum east germany whereabouts remained unknown 1990 carried rolls deserter carney finally apprehended fall berlin wall special agents united states air force office special investigations afosi april 22 1991 pintschstrasse 12 friedrichshain district berlin carney entered u.s. air force december 1980 april 1982 april 1984 assigned 6912th electronic security group electronic security command tempelhof central airport berlin linguist intelligence specialist duty station 6912th marienfelde field site zdf film informationen um jeden preis carney admitted homosexuality primary reason became spy carney quickly became disillusioned air force intelligence gathering operations several stories attempting turn badge quit protest first-hand experiences nato exercise able archer 83 strengthened resolve help avoid nuclear conflict later lonely alienated psychological stress felt one talk problems intended defect east germany first crossing allowed drawn espionage east german intelligence agents expertly manipulated claimed complete loyalty working marienfelde field site berlin carney began copying classified documents provided stasi repeatedly crossing back forth east germany 1984 involuntarily transferred goodfellow air force base texas work technical instructor carney believed goodfellow training base real-world intelligence interest stasi soon discovered wrong carney continued providing stasi documents meeting handlers mexico city rio de janeiro 1985 feeling cut supervisors east berlin increasing risk became known year spy sought protection east german embassy mexico city flown havana assistance cuban government weeks later returned east berlin via prague continued work stasi hva abt xi ha iii intercepting translating non-secure telephone communications u.s. military commanders well east german telephone lines dedicated u.s. embassy east berlin course spying carney provided stasi eastern bloc intelligence services one hundred top-secret u.s. military documents services east germany awarded nva service medal bronze medal waffenbrüderschaft brotherhood arms gold internal stasi file shows value work performed stasi kgb earning praise kgb general chebrikov well general zaitsev group soviet forces germany gsfg break case came fall berlin wall november 1989 many stasi records became available foreign investigators journalists april 1991 carney located help least two former stasi intelligence officers turned informants preparation apprehension quickly assigned 7350th air base group former base tempelhof central airport several months apprehension ironically assignment official unintended consequence assigning carney unit supported desert shield/desert storm 1991 result carney received national defense service medal solitary confinement fort leavenworth kansas several years later 22 april 1991 carney apprehended public street afosi agents near residence pintschstraße 12 friedrichshain used soviet sector berlin immediately following apprehension taken tempelhof airport identified underwent nearly 28 hours intense interrogation carney refused answer questions repeated requests counsel denied point afosi consultation u.s. agencies decided quietly remove carney german territory secretly flown united states aboard military aircraft following day carney arrest return united states coordinated highest levels united states government without consulting german officials u.s ambassador federal republic germany vernon walters personally acted adviser commander-in-chief united states air forces europe urging haste carney pleaded guilty charges espionage conspiracy desertion sentenced december 1991 38 years prison carney served mandatory portion sentence quantico virginia later united states disciplinary barracks fort leavenworth kansas carney released 2002 serving 11 years seven months twenty days twenty-year sentence accordance pretrial agreement release prison carney attempted return germany claiming german citizen however east germany never naturalized citizen thus obtained german passport fraudulently german authorities refused grant passport reported living ohio november 2011 carney submitted lengthy manuscript detailing life spy united states air force security review numerous delays manuscript finally cleared july 26 2012 book enemies american cold war journey published 2013
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Computer security
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runtime library computer programming runtime library rtl set low-level routines used compiler invoke behaviors runtime environment inserting calls runtime library compiled executable binary runtime environment implements execution model built-in functions fundamental behaviors programming language execution run time computer program execution calls runtime library cause communication executable binary runtime environment runtime library often includes built-in functions memory management exception handling therefore runtime library always specific platform compiler runtime library may implement portion runtime environment behavior one reads code calls available typically thin wrappers simply package information send runtime environment operating system however sometimes term runtime library meant include code runtime environment even though much code directly reached via library call example language features performed efficient accurate runtime implemented runtime environment may invoked via runtime library api e.g logic errors array bounds checking dynamic type checking exception handling possibly debugging functionality reason programming bugs discovered program tested live environment real data despite sophisticated compile-time checking testing performed development another example runtime library may contain code built-in low-level operations complicated inlining compilation implementations arithmetic operations directly supported targeted cpu various miscellaneous compiler-specific operations directives concept runtime library confused ordinary program library like created application programmer delivered third party dynamic library meaning program library linked run time example c programming language requires minimal runtime library commonly called codice_1 defines large standard library called c standard library provided implementation
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Programming language topics
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python package manager python package manager pypm python utility intended simplify tasks locating installing upgrading removing python packages determine recent version software package installed system install upgrade package local remote host pypm non-free may used activestate activepython distribution pypm uses “ pypm repositories ” collections pre-compiled packages repositories contain high variety modules published pypi pypm inspired perl package manager ppm
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Operating systems
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john mashey john r. mashey born 1946 us computer scientist director entrepreneur mashey holds ph.d. computer science pennsylvania state university developed assist assembler language teaching software worked pwb/unix operating system bell labs 1973 1983 authoring pwb shell also known mashey shell moved silicon valley join convergent technologies ending director software joined mips computer systems early 1985 managing operating systems development helping design mips risc architecture well specific cpus systems software continued similar work silicon graphics 1992–2000 contributing design numaflex modular computer architecture using numalink ending vp chief scientist mashey one founders standard performance evaluation corporation spec benchmarking group acm national lecturer four years guest editor ieee micro one long-time organizers hot chips conferences chaired technical conferences operating systems cpu chips gave public talks software engineering risc design performance benchmarking supercomputing credited first spread term concept big data 1990s became consultant venture capitalists high-tech companies trustee computer history museum 2008 2012 received usenix lifetime achievement award flame award contributions unix community since early days written articles skeptical inquirer regarding climate change denial 2010 published 250-page critical report wegman report mashey report concluded wegman report contained plagiarized text story featured usa today interviewed science magazine stated spending retirement years compiling voluminous critiques calls 'real conspiracy produce 'climate antiscience research investigated secretive funding climate contrarian thinktanks mashey blogs desmogblog focuses global warming mashey became scientific technical consultant committee skeptical inquiry 2015 mashey married angela hey cambridge university waterloo university graduate ph.d. imperial college london
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Operating systems
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cooperative database cooperative database type database holds information customers transactions many companies contribute information database return aggregate information customers companies provided databases used promotional mailings credit card fraud detection fighting e-mail spam alternatively term cooperative database used describe database systems incorporate techniques aid users beyond returning direct answers databases example give explanations query returns results detect report user misconception suggested query provide justifications returned answers relax query attributes find close non-precise answers fundamental goal extend databases towards reflecting cooperative principle particular avoid misleading users omission pertinent contextual detail
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Computer security
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file attribute file attributes metadata associated computer files define file system behavior attribute one two states set cleared attributes considered distinct metadata dates times filename extensions file system permissions addition files folders volumes file system objects may attributes traditionally ms-dos microsoft windows four attributes archive hidden read-only system windows added new ones systems derived 4.4bsd-lite freebsd netbsd openbsd dragonfly bsd macos sets system user attributes newer versions linux kernel also support set file attributes traditionally dos microsoft windows files folders accepted four attributes new versions windows came microsoft added inventory available attributes ntfs file system including limited attributes displayed attributes column windows explorer include 4.4bsd 4.4bsd-lite files directories folders accepted four attributes could set owner file superuser user attributes two attributes could set superuser system attributes freebsd added additional attributes also supported dragonfly bsd freebsd also supports whereas dragonfly bsd supports netbsd added another attribute also supported openbsd macos added three attributes dos os/2 windows codice_3 command cmd.exe command.com used change display four traditional file attributes file explorer windows show seven mentioned attributes set clear system attribute windows powershell become component windows 7 later features two commands read write attributes codice_4 codice_5 change attribute file windows nt user must appropriate file system permissions known write attributes write extended attributes 4.4bsd 4.4bsd-lite derivatives codice_6 codice_7 commands used change display file attributes change user attribute file 4.4bsd-derived operating systems user must owner file superuser change system attribute user must superuser linux codice_8 codice_9 commands used change display file attributes
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Computer file systems
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ctrls ctrls tier-4 datacenter india headquartered hyderabad deals large group networked computer servers typically used various organizations remote storage processing distribution large amounts data large groups remote servers networked allow centralized data storage online access computer services resources ctrls belongs industry hyderabad branches mumbai delhi ctrls datacenters founded 2008 hyderabad india established aim keep online applications data secure provide network storage services various organizations sridhar pinnapureddy founder ceo ctrls spearheaded 200 innovations energy management dc infra cloud disaster recovery also founder chairman pioneer group companies interests internet services infrastructure picked recognitions outstanding entrepreneur year – 2010 asia pacific region apea rajiv gandhi shiromani global economic council karamveer puraskar 2007 awarded icongo accomplishments contributions society ctrls developed capabilities provide platform level services include data center infrastructure storage backup hardware os layers network security layers offers services disaster recovery demand managed services private cloud-on-demand enable clients make paradigm shift captive datacenter model outsourced one tier 4 data centers ctrls located hyderabad mumbai delhi bangalore headquarters hyderabad
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Distributed computing architecture
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assist computing assist assembler system student instruction systems teaching ibm system/370-compatible assembler interpreter developed early 1970s penn state university graham campbell john mashey plus student assistants late 1960s computer science education expanded rapidly university computer centers faced large growth usage students whose needs sometimes differed professionals batch processing environments needed run short programs decks punched cards fast turnaround minutes overnight programs often included syntax errors compiled would often fault quickly optimization flexibility far less important low overhead watfiv successful pioneering effort build fortran compiler tuned student use universities began running dedicated fast-batch memory partition small run-time limit 5 seconds ibm system/360 model 67 low limit enabled fast turnaround avoided waste time programs stuck infinite loops watfiv success helped inspire development assist pl/c student-oriented programs fit fast-batch model became widely used among universities assist enhanced promoted others northern illinois university wilson singletary ross overbeek university tennessee charles hughes charles pfleeger reported 1978 assist used 200+ universities 1980s niu new implementation ibm pcs assist/i interactive used computer scientist john ehrman teach boot camp course assembly programming share computing meetings least 2011 perhaps several years march 1 1998 penn state declared assist longer copyrighted program freely available per last release notes original assist code seems still get use seen 2017 demonstration video assembling source running mvs 3.8 emulation laptop ibm system/360 /370 computers used 24-bit addressing ignored high-order 8 bits assembly programmers era including wrote assist often saved precious memory using high-order 8 bits flags required compatibility mode ibm introduced 31-bit 64-bit addressing
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Programming language topics
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lexicase lexicase type dependency grammar originally developed beginning early 1970s stanley starosta university hawaii dozens starosta graduate students also contributed theory wrote least 20 doctoral dissertations using lexicase analyze numerous languages asia japanese mandarin vietnamese thai khmer tagalog etc europe greek russian etc africa swahili yoruba lexicase monostratal x-bar grammar i.e transformational grammar words heads phrases i.e assumed empty phrases lexicase words features determine morphosyntactic distribution dependents primary goal lexicase provide simple transparent disprovable means testing cross-linguistic tendencies lexically focused theory lexicase used identify verb subcategories korean russian thai vietnamese noun subcategories khmer thai provide overall language description pacoh central vietnam regarding arguments clause structure used explore case greek mandarin chinese transitivity ergativity amis indigenous language taiwan proto-central pacific austronesian among topics
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Computational linguistics
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12-channel carrier system u.s. telephone network 12-channel carrier system early frequency-division multiplexing system standard used carry multiple telephone calls single twisted pair wires mostly short medium distances system twelve voice channels multiplexed high frequency carrier passed balanced pair trunk line similar used individual voice frequency connections original system obsolete today multiplexing voice channels units 12 24 channels modern digital trunk lines t-1 legacy system twelve channel scheme first devised early 1930s provide line spectrum covering 60 108 khz type j carrier telephone system equivalent four wire two wire facilities open wire carrier used almost exclusively interstate long haul toll telephony became basic building block channel group succeeding long haul systems type k type l systems late 1970s long haul channel groups used single-sideband/suppressed carrier heterodyne scheme produced western electric type a-1 a-6 channel bank twelve channel scheme order maintain bandwidth routing compatibility carried short haul carriers well started developing eliminate voice band open wire trunk lines 1950s bell system vacuum-tube driven n-1 carrier early 1950s used twelve channel carrier system using double sideband/unsuppressed carrier operation n't need network timebase synchronization maintain frequency accuracy n-2 similar heterodyning scheme discrete transistorized plug-in unit architecture n3 used frequency plan scheme using single sideband different voice channel side carrier technique first seen 16 channel type open wire short haul carrier 1950s doubled capacity 24 channels basic digital type pcm carrier introduced late 1950s became now-ubiquitous t-1 digital world repeaters spaced approximately 6 miles 10 km apart depending wire gauge exceptions n-carriers used 19 gage unloaded toll pairs two-wire operation repeater either received directions low frequency band sent directions higher band vice versa frequency frogging allowed equivalent four-wire operation single cable pair two-wire operation period type n-1 widespread use lenkurt corporation owned controlled general telephone fielded variant competitor type bn bn used pairs repeaters bell n-cxr used four channel groups lower single-sideband heterodyning 24 channels per carrier later seen western electric type n-3 type bn used times bell operating companies 1956 hush-a-phone decision us supreme court landmark case challenged benign monopoly us telephone equipment industry part settlement bell operating companies buy use small amounts lenkurt collins microwave carrier systems california type bn used almost exclusively provide trunk private line connections pacific tel tel toll offices local general telephone end offices
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Internet protocols
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anonymous call rejection north american nanp telephone system anonymous call rejection acr landline calling feature screens calls callers blocked caller id information often free included caller id landlines may available separately local telephone company feature available cellphone services caller id sprint t-mobile usa verizon wireless provide service acr prevents dialing feature code successfully calling customer service verizon wireless currently provide blocked anonymous call rejection north america feature enabled vertical service code *77 disabled *87 anonymous call rejection service callers block number get recording saying accept blocked calls anonymous call rejection service callers block number reach
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Computer security
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palmpilot professional palmpilot professional personal digital assistant palmpilot released march 10 1997 updated version pilot 5000 delayed general availability professional model marketplace marketed compact design back-lit display ability quickly connect microsoft windows macintosh personal computer ability synchronize via cradle modem sold separately computer making possible send e-mails set appointments others set contact information various third party applications upirc enabled connecting various messaging systems including popular instant messaging services optional memory card ir port available upgrade directly palm
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Computer architecture
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programming language also known dlang multi-paradigm system programming language created walter bright digital mars released 2001 andrei alexandrescu joined design development effort 2007 though originated re-engineering c++ distinct language redesigned core c++ features also sharing characteristics languages notably java python ruby c eiffel design goals language attempt combine performance safety compiled languages expressive power modern dynamic languages idiomatic code commonly fast equivalent c++ code also shorter language whole memory-safe include optional attributes designed check memory safety type inference automatic memory management syntactic sugar common types allow faster development bounds checking design contract features concurrency-aware type system help reduce occurrence bugs designed lessons learned practical c++ usage rather purely theoretical perspective although uses many c c++ concepts also discards compatible c c++ source code however constrained design rule code legal c behave way gained features c++ example closures anonymous functions compile time function execution adds functionality c++ also implementing design contract unit testing true modules garbage collection first class arrays associative arrays dynamic arrays array slicing nested functions lazy evaluation re-engineered template syntax retains c++ ability perform low-level programming add inline assembler c++ multiple inheritance replaced java-style single inheritance interfaces mixins hand declaration statement expression syntax closely matches c++ inline assembler typifies differences application languages like java c inline assembler lets programmers enter machine-specific assembly code within standard code method often used system programmers access low-level features processor needed run programs interface directly underlying hardware operating systems device drivers built-in support documentation comments allowing automatic documentation generation supports five main programming paradigms imperative object-oriented metaprogramming functional concurrent actor model imperative programming almost identical c. functions data statements declarations expressions work c c runtime library may accessed directly hand notable differences c area imperative programming include codice_1 loop construct allows looping collection nested functions functions declared inside another may access enclosing function local variables object-oriented programming based single inheritance hierarchy classes derived class object support multiple inheritance instead uses java-style interfaces comparable c++ pure abstract classes mixins separates common functionality inheritance hierarchy also allows defining static final non-virtual methods interfaces metaprogramming supported combination templates compile time function execution tuples string mixins following examples demonstrate compile-time features templates written imperative style compared c++ functional style templates regular function calculates factorial number ulong factorial ulong n use codice_2 compile-time conditional construct demonstrated construct template performs calculation using code similar function template factorial ulong n following two examples template function defined used compute factorials types constants need specified explicitly compiler infers types right-hand sides assignments enum fact_7 factorial 7 example compile time function execution ordinary functions may used constant compile-time expressions provided meet certain criteria enum fact_9 factorial 9 codice_3 function performs codice_4-like data formatting also compile-time ctfe msg pragma displays result compile time import std.string format pragma msg format 7 fact_7 pragma msg format 9 fact_9 string mixins combined compile-time function execution allow generating code using string operations compile time used parse domain-specific languages code compiled part program import footod // hypothetical module contains function parses foo source code void main supports functional programming features function literals closures recursively-immutable objects use higher-order functions two syntaxes anonymous functions including multiple-statement form shorthand single-expression notation two built-in types function literals codice_5 simply pointer stack-allocated function codice_6 also includes pointer surrounding environment type inference may used anonymous function case compiler creates codice_6 unless prove environment pointer necessary likewise implement closure compiler places enclosed local variables heap necessary example closure returned another function exits function scope using type inference compiler also add attributes codice_8 codice_9 function type prove apply functional features currying common higher-order functions map filter reduce available standard library modules codice_10 codice_11 alternatively function compositions expressed using uniform function call syntax ufcs natural left-to-right reading import std.stdio std.concurrency std.variant void foo void main memory usually managed garbage collection specific objects may finalized immediately go scope explicit memory management possible using overloaded operators codice_12 codice_13 simply calling c malloc free directly garbage collection controlled programmers may add exclude memory ranges observed collector disable enable collector force either generational full collection cycle manual gives many examples implement different highly optimized memory management schemes garbage collection inadequate program safed name given subset guaranteed memory safe writes memory allocated already recycled functions marked codice_14 checked compile time ensure use features could result corruption memory pointer arithmetic unchecked casts functions called must also marked codice_14 codice_16 functions marked codice_16 cases compiler distinguish safe use feature disabled safed potential case memory corruption initially banners dip1000 dip25 part language specification provides protections certain ill-formed constructions involving lifetimes data current mechanisms place primarily deal function parameters stack memory however stated ambition leadership programming language provide thorough treatment lifetimes within programming language within safe code lifetime assignment involving reference type checked ensure lifetime assignee longer assigned example applied function parameter either pointer type references keywords return scope constrain lifetime use parameter standard dictates following behaviour annotated example given c application binary interface abi supported well c fundamental derived types enabling direct access existing c code libraries bindings available many popular c libraries additionally c standard library part standard d. microsoft windows access component object model com code takes permissive realistic approach interoperation c++ code code marked extern c++ following features specified c++ namespaces used via syntax extern c++ namespace namespace name c++ namespace c++ side using namespace std class base class derived public base int derived :mul int factor derived *createinstance int void deleteinstance derived side programming language official subset known better c subset forbids access features requiring use runtime libraries c accessed via- current implementations -betterc flag compilation better c may call code compiled flag linked code code compiled without better c option may call code compiled however lead slightly different behaviours due differences c handle asserts walter bright decided start working new language 1999 first released december 2001 reached version 1.0 january 2007 first version language d1 concentrated imperative object oriented metaprogramming paradigms similar c++ dissatisfied phobos official runtime standard library members community created alternative runtime standard library named tango first public tango announcement came within days 1.0 release tango adopted different programming style embracing oop high modularity community-led project tango open contributions allowed progress faster official standard library time tango phobos incompatible due different runtime support apis garbage collector threading support etc. made impossible use libraries project existence two libraries widely use led significant dispute due packages using phobos others using tango june 2007 first version d2 released beginning d2 development signalled stabilization d1 first version language placed maintenance receiving corrections implementation bugfixes d2 introduce breaking changes language beginning first experimental const system d2 later added numerous language features closures purity support functional concurrent programming paradigms d2 also solved standard library problems separating runtime standard library completion d2 tango port announced february 2012 release andrei alexandrescu book programming language 12 june 2010 marked stabilization d2 today commonly referred january 2011 development moved bugtracker patch-submission basis github led significant increase contributions compiler runtime standard library december 2011 andrei alexandrescu announced d1 first version language would discontinued 31 december 2012 final d1 release v1.076 31 december 2012 code official compiler digital mars compiler walter bright originally released custom license qualifying source available conforming open source definition 2014 compiler front-end re-licensed open source boost software license re-licensed code excluded back-end partially developed symantec 7 april 2017 entire compiler made available boost license symantec gave permission re-license back-end 21 june 2017 language accepted inclusion gcc gcc 9 language frontend merged gcc current implementations compile directly machine code efficient execution editors integrated development environments ides supporting include eclipse microsoft visual studio slickedit emacs vim scite smultron textmate monodevelop zeus geany among others open source ides windows exist written poseidon d-ide entice designer applications debugged using c/c++ debugger like gdb windbg although support various d-specific language features extremely limited windows programs debugged using ddbg microsoft debugging tools windbg visual studio converted debug information using cv2pdb zerobugs debugger linux experimental support language ddbg used various ides command line zerobugs graphical user interface gui example program prints command line arguments codice_18 function entry point program codice_19 array strings representing command line arguments codice_20 array characters represented codice_21 d1 codice_22 d2 codice_1 statement iterate collection case producing sequence indexes codice_24 values codice_25 array codice_19 index codice_24 value codice_25 types inferred type array codice_19 following shows several capabilities design trade-offs short program iterates lines text file named codice_30 contains different word line prints words anagrams words notable organisations use programming language projects include facebook ebay netflix successfully used aaa games javascript virtual machine operating system kernel gpu programming web development numerical analysis gui applications passenger information system
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Programming language topics
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tsig tsig transaction signature computer-networking protocol defined rfc 2845 primarily enables domain name system dns authenticate updates dns database commonly used update dynamic dns secondary/slave dns server tsig uses shared secret keys one-way hashing provide cryptographically secure means authenticating endpoint connection allowed make respond dns update although queries dns may usually made without authentication updates dns must authenticated since make lasting changes structure internet naming system update request may arrive via insecure channel internet one must take measures ensure authenticity integrity request use key shared client making update dns server helps ensure authenticity integrity update request one-way hashing function serves prevent malicious observers modifying update forwarding destination thus ensuring integrity message source destination timestamp included tsig protocol prevent recorded responses reused would allow attacker breach security tsig places requirement dynamic dns servers tsig clients contain accurate clock since dns servers connected network network time protocol provide accurate time source dns updates like queries normally transported via udp since requires lower overhead tcp however dns servers support udp tcp requests update specified rfc 2136 set instructions dns server include header zone updated prerequisites must satisfied record updated tsig adds final record includes timestamp hash request also includes name secret key used sign request rfc 2535 recommendations form name response successful tsig update also signed tsig record failures signed prevent attacker learning anything tsig key using specially crafted update probes nsupdate program use tsig dns updates tsig record format records update request meaning fields described rfc 1035 although tsig widely deployed several problems protocol result number alternatives extensions proposed
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Internet protocols
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exofs exofs formerly known osdfs object-based file system implemented top external object store name stands extended object file system referring use ext2-based metadata object storage devices exofs originally developed avishay traeger ibm hrl originally based ext2 file system since 2008 panasas develops maintains exofs open-osd.org exofs included mainline linux kernel since version 2.6.30-rc1 linux distribution implemented utility making file systems exofs current kernel line removed version 5.1-rc1
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Computer file systems
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fp programming language fp short function programming programming language created john backus support function-level programming paradigm allows eliminating named variables language introduced backus 1977 turing award lecture programming liberated von neumann style subtitled functional style algebra programs paper sparked interest functional programming research eventually leading modern functional languages function-level paradigm backus hoped fp never found much use outside academia 1980s backus created successor language fl remained research project values fp programs map one another comprise set closed sequence formation values built set atoms booleans integers reals characters etc ⊥ undefined value bottom sequences bottom-preserving fp programs functions f map single value x another functions either primitive i.e. provided fp environment built primitives program-forming operations also called functionals example primitive function constant transforms value x constant-valued function x̄ functions strict another example primitive function selector function family denoted 1,2 ... contrast primitive functions functionals operate functions example functions unit value 0 addition 1 multiplication functional unit produces value applied function f one core functionals fp addition constructed primitives functionals function may defined recursively equation simplest kind e f expression built primitives defined functions function symbol f using functionals fp84 extension fp include infinite sequences programmer-defined combining forms analogous backus added fl successor fp lazy evaluation unlike ffp another one backus variations fp fp84 makes clear distinction objects functions i.e. latter longer represented sequences former fp84 extensions accomplished removing fp restriction sequence construction applied non -⊥ objects fp84 entire universe expressions including whose meaning ⊥ closed sequence construction fp84 semantics embodied underlying algebra programs set function-level equalities may used manipulate reason programs
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Programming language topics
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inference attack inference attack data mining technique performed analyzing data order illegitimately gain knowledge subject database subject sensitive information considered leaked adversary infer real value high confidence example breached information security inference attack occurs user able infer trivial information robust information database without directly accessing object inference attacks piece together information one security level determine fact protected higher security level
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Computer security
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cloudstore cloudstore kfs previously kosmosfs kosmix c++ implementation google file system parallels hadoop project implemented java programming language cloudstore supports incremental scalability replication checksumming data integrity client side fail-over access c++ java python fuse module file system mounted linux september 2007 kosmix published kosmosfs open source last commit activity 2010 google code page kosmosfs points quantcast file system github successor kfs former project sourceforge used name cloudstore 2008
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Computer file systems
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utah glx utah glx project aimed creating fully free open-source basic hardware-accelerated 3d renderer using opengl rendering api linux kernel-based operating systems utah glx predates direct rendering infrastructure used 2014 john d. carmack worked utah glx
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Operating systems
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trusteer trusteer portfolio digital identity trust software products belonging ibm security founded mickey boodaei rakesh k. loonkar israel 2006 trusteer acquired september 2013 ibm 1 billion highest valuation multiple ibm ever paid business ibm trusteer helps organizations seamlessly establish digital identity trust across web customer journey cloud-based intelligence backed ai patented machine learning trusteer provides holistic approach identifying new existing customers without negatively impacting user experience 500 leading organizations rely trusteer help enable secure customers ’ digital journey support business growth trusteer presence north america south america europe africa japan ibm trusteer helps brands accelerate digital growth establishing digital identity trust across channels helping recognize customers deter bad actors trusteer rapport adaptive endpoint solution helps protect financial institutions end-users transparently detecting protecting financial malware infections phishing attacks account takeover provides comprehensive security layer anti-virus software typically designed address financial malicious activity software service offering uses 24/7 threat intelligence including geographic customize detection matrix address new threats real-time including attacking specific financial institution used leading financial institutions worldwide trusteer rapport combines global footprint millions endpoints years threat data analysis experience innovative technology achieve high rates detection low false positives increasingly sophisticated financial threat environment specifically trusteer rapport detects alerts organization pharming phishing screenshots overlays financial malware advises end-user account risk compromised moment installed end-user ’ computer trusteer rapport immediately checks removes existing financial malware malicious patches starts performing continuous transparent monitoring kernel operating system browser application levels protect new threats trusteer rapport supports browser extensions google chrome microsoft edge apple safari mozilla firefox supports microsoft internet explorer use trusteer rapport end-users simply install rapport browser extension web browser choice trusteer rapport compatible microsoft windows 7 higher multiple mac os x versions supported browsers platforms end-users download trusteer rapport free charge financial institutions offer software free charge offer safer online banking customers organizations also acquire trusteer mobile sdk extend protection native mobile applications trusteer pinpoint platform digital identity trust lifecycle platform designed provide b2c access management dynamically managing digital identity trust web mobile applications platform made three products trusteer pinpoint platform allows organizations improve digital customer journey single platform dynamically manage risk-based seamless authentication user-friendly step-up authentication establish trust identity proofing new guest users happens need validate new anonymous customer user true customer intent initiating payment fraud abusing loyalty program guests new customers let unimpeded ones complete step-up authentication using advanced intelligence global visibility ibm trusteer pinpoint™ assure solution designed help detect predict risk fraudulent intent new guest customers also enables companies conduct early account monitoring new accounts ’ type insight ’ critical reducing abandonment caused friction security measures increasing loyalty program registrations growing digital channel sustain trust continuous authentication trusted users better protect customer accounts payment journeys compromised detecting account takeovers unauthorized logins activity requires comprehensive view account access device session user perspective ibm trusteer pinpoint detect delivers kind visibility using behavioral biometric capabilities behavioral analytics transparently build user profiles continually authenticate online identities using machine learning patented analytics platform analyzes patterns mouse movements astonishing speeds volumes differentiate account user ’ “ normal ” digital behavior abnormal behavior insight combined device activity evidence transactional data geolocation data either abnormal user behavior known fraudster behavior detected trusteer pinpoint detect provides recommended action real-time along detailed reasoning session details organization take steps confirm trust necessary confirm trust combine risk assessment strong adaptive authentication confirm trust abnormal user behavior suspicious activity identified ibm trusteer pinpoint verify cloud-based authentication service seamlessly integrates pinpoint assure pinpoint detect help companies apply strong step-up authentication necessary application developers simply use exposed interfaces service challenge users perform second factor authentication via digital application users choose enroll various forms two-factor authentication one-time passcodes via email sms mobile push notification biometric authentication trusteer pinpoint products use context- based intelligence combining device id proxy emulator detection malware remote access trojan rat infection detection bot detection email phone number intelligence account history patterns behavioral biometrics navigation session analysis determine trust risk level associated user trusteer mobile sdk helps organizations build digital identity trust mobile confidence customers differentiating trusted mobile devices users suspicious ones exposes real-time mobile risk allow account compromise mitigation proactively detects mobile device risk native mobile applications available standalone assessing risk indicators mobile device integrates ibm trusteer pinpoint digital identity trust platform use threat intelligence correlate mobile device user behavior account risk factors across digital channels specifically ibm trusteer mobile sdk generates strong persistent global device id uses robust set capabilities detect mobile device risks real-time applies machine learning analytics offer actionable insights suspicious mobile user behavior threat detection capabilities include real-time overlay attacks emulators sms stealers remote access tools rats insecure wi-fi networks active pharming rooting jailbreaking uses server-side trusteer pinpoint capabilities correlated aggregated awareness device anomalies user behavior account risk indicators—such account takeover phishing attacks malware infections compromised credentials advanced evasion methods—across digital channels also works seamlessly trusteer pinpoint platform detect protect mobile device fraudulent activity early digital account creation process guest user new mobile device introduced trusteer apex automated solution tries prevent exploits malware compromising endpoints extracting information apex three layers security exploit prevention data exfiltration prevention credentials protection apex protects employee credentials phishing attacks validating employees submitting credentials authorized enterprise web-application login urls apex also prevents corporate employees re-using corporate credentials access non-corporate public applications like paypal e-bay facebook twitter apex requires users provide different credentials applications lower risk credentials exposure trusteer apex targeted behaviors small group applications hypothesis responsible overwhelming majority exploits namely java adobe ’ reader flash microsoft ’ office technology behind trusteer apex rely threat signatures so-called whitelists good applications instead watches applications run spots suspicious malicious behavior based knowledge normal application behavior refined large user base trusteer claims apex block web-based attacks used implant malware exploiting vulnerable applications data loss due malware infections spotting attempts untrusted applications processes send data outside organization connect internet-based command control c c networks end users reported problems rapport slow pcs due high cpu ram utilization incompatibility various security/antivirus products difficulty removing software presentation given 44con september 2011 bypassing trusteer rapport keylogger protection shown relatively trivial shortly thereafter trusteer confirmed flaw corrected said even hacker able use flaw disable anti-keylogging functions rapport secondary security protection technologies would still play rapport software incompatible windows tool driver verifier may cause blue screen system crash since driver verifier intended end users production environment workstations trusteer support recommends end users run driver verifier trusteer endpoint protection installed march 2011 blue gem rival company filed lawsuit trusteer california court blue gem accused trusteer plagiarizing code order maintain compatibility anti-keystroke logging software types intel chipset first introduced back 2007 trusteer described accusations baseless
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Computer security
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patch tuesday patch tuesday also known update tuesday unofficial term used refer microsoft regularly releases software patches software products widely referred way industry microsoft formalized patch tuesday october 2003 patch tuesday occurs second sometimes fourth tuesday month north america far integrated windows update wu function concerned patch tuesday begins 18:00 17:00 utc 10:00 pst utc−8 10:00 pdt utc−7 updates show download center added wu kb articles technet bulletin unlocked later microsoft pattern releasing larger number updates even-numbered months fewer odd-numbered months minor updates also released outside patch tuesday daily updates consist malware database refreshes windows defender microsoft security essentials sometimes extraordinary patch tuesday two weeks regular patch tuesday updates could released time starting windows 98 microsoft included windows update installed executed would check patches windows components microsoft would release intermittently release microsoft update system also checks updates microsoft products microsoft office visual studio sql server earlier versions windows update suffered two problems microsoft introduced patch tuesday october 2003 reduce cost distributing patches system accumulates security patches month dispatches second tuesday month event system administrators may prepare following day informally known exploit wednesday marks time exploits may appear wild take advantage unpatched machines newly announced vulnerabilities tuesday chosen optimal day week distribute software patches done maximize amount time available upcoming weekend correct issues might arise patches leaving monday free address unanticipated issues might arisen preceding weekend obvious security implication security problems solution withheld public month policy adequate vulnerability widely known extremely obscure always case cases vulnerability information became public actual worms circulating prior next scheduled patch tuesday critical cases microsoft issues corresponding patches become ready alleviating risk updates checked installed frequently ignite 2015 event microsoft revealed change distributing security patches release security updates home pcs tablets phones soon ready enterprise customers stay monthly update cycle reworked windows update business many exploitation events seen shortly release patch analysis patch helps exploit developers immediately take advantage previously undisclosed vulnerability remain unpatched systems therefore term exploit wednesday coined microsoft warned users discontinued support windows xp starting april 8 2014 users running windows xp afterwards would risk attacks security patches newer windows versions reveal similar vulnerabilities present newer older windows versions allow attacks devices unsupported windows versions c.f zero-day attacks however microsoft stopped fixing vulnerabilities unsupported windows versions regardless widely known vulnerabilities became leaving vulnerabilities unfixed devices running windows versions vulnerable attacks microsoft made singular exception rapid spread wannacry ransomware released patches may 2017 unsupported windows xp windows 8 windows server 2003 addition supported windows versions windows vista extended support ended april 11 2017 leave vulnerabilities discovered afterwards unfixed creating situation vista xp windows 7 service pack 1 support already run without support end january 14 2020 january 10 2023 windows 8.1 cause unfixed vulnerabilities issue users operation systems support windows 8 already ended january 12 2016 users install windows 8.1 windows 10 continue get support support windows 7 without sp1 ended april 9 2013 ability install sp1 continue get support 2020 install windows 8.1 windows 10 receive support 2020 one major change introduction windows 10 microsoft started release new version windows 10 twice per year microsoft modern lifecycle policy newly released windows 10 version starts grace period previous version regard support unlike previous windows products received infrequent updates via service packs support governed fixed lifecycle policy new policy home pro versions windows 10 provided security feature updates called mainstream support 18 months release enterprise education versions 24 months give example support windows 10 home/pro version 1703 released april 2017 stopped microsoft october 2018 support versions 1507 1511 released 2015 officially ended 2017 microsoft announced would give extended support security feature updates least one semi-annual channel sac windows 10 version october 14 2025 according microsoft device needs install latest version feature update current version reaches end service help keep device secure remain supported microsoft previous windows operating systems device running unsupported version windows longer receives security patches potentially affected unfixed vulnerabilities issue beginning end support date counter microsoft designed update system home pro editions windows 10 cases technically possible latest windows version downloaded installed automatically however drawn criticism due problems forced upgrades introduce addition commonly used editions like home pro microsoft offers specialized long-term servicing branch ltsb long-term servicing channel ltsc versions windows 10 longer support timelines governed microsoft fixed lifecycle policy e.g windows 10 enterprise 2016 ltsb receive extended support october 13 2026 sap security patch day company advises users install security updates chosen coincide patch tuesdays adobe systems update schedule flash player since november 2012 also coincides patch tuesday one reasons flash player comes part windows starting windows 8 flash player updates built-in plugin based version need published time order prevent reverse-engineering threats windows update uses background intelligent transfer service bits download updates using idle network bandwidth however bits use speed reported network interface nic calculate bandwidth lead bandwidth calculation errors example fast network adapter e.g 10 mbit/s connected network via slow link e.g 56 kbit/s according microsoft bits compete full bandwidth nic ... bits visibility network traffic beyond client furthermore windows update servers microsoft honor tcp slow-start congestion control strategy result users network may experience significantly slower connections machines actively retrieving updates particularly noticeable environments many machines individually retrieve updates shared bandwidth-constrained link found many multi-pc homes small medium-sized businesses bandwidth demands patching large numbers computers reduced significantly deploying windows server update services wsus distribute updates locally addition updates downloaded microsoft servers windows 10 devices share updates peer-to-peer fashion windows 10 devices local network even windows 10 devices internet potentially distribute updates faster reducing usage networks metered connection
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Computer security
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virtual machine escape computer security virtual machine escape process breaking virtual machine interacting host operating system virtual machine completely isolated guest operating system installation within normal host operating system 2008 vulnerability cve-2008-0923 vmware discovered core security technologies made vm escape possible vmware workstation 6.0.2 5.5.4 fully working exploit labeled cloudburst developed immunity inc. immunity canvas commercial penetration testing tool cloudburst presented black hat usa 2009
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Computer security
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nokia n71 nokia n71 smartphone announced nokia november 2 2005 released june 2006 nokia joint-first clamshell smartphone like n92 announced day n71 runs symbian os v9.1 s60 3rd edition features include 2 megapixel camera built-in flash front vga camera allow real-time video calling fm radio bluetooth digital music player functionality comes standard full web browser support 3d java games also 3g mini-sd card slot expandable memory features include ability transfer data via w-cdma 2100 gprs edge nokia promotes n71 2-megapixel digital rear camera producing high-quality photography video well music radio functionality phone multimedia mini-sd card means hold 2 gigabytes equating potentially hundreds tracks according nokia specifications
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Operating systems
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address space layout randomization address space layout randomization aslr computer security technique involved preventing exploitation memory corruption vulnerabilities order prevent attacker reliably jumping example particular exploited function memory aslr randomly arranges address space positions key data areas process including base executable positions stack heap libraries linux pax project first coined term aslr published first design implementation aslr july 2001 patch linux kernel seen complete implementation providing also patch kernel stack randomization since october 2002 first mainstream operating system support aslr default openbsd version 3.4 2003 followed linux 2005 address space randomization hinders types security attacks making difficult attacker predict target addresses example attackers trying execute return-to-libc attacks must locate code executed attackers trying execute shellcode injected stack find stack first cases system obscures related memory-addresses attackers values guessed mistaken guess usually recoverable due application crashing address space layout randomization based upon low chance attacker guessing locations randomly placed areas security increased increasing search space thus address space randomization effective entropy present random offsets entropy increased either raising amount virtual memory area space randomization occurs reducing period randomization occurs period typically implemented small possible systems must increase vma space randomization defeat randomization attackers must successfully guess positions areas wish attack data areas stack heap custom code useful data loaded one state attacked using nop slides code repeated copies data allows attack succeed area randomized one handful values contrast code areas library base main executable need discovered exactly often areas mixed example stack frames injected onto stack library returned following variables declared calculate probability attacker succeeding assume number attempts carried without interrupted signature-based ips law enforcement factor case brute forcing daemon restarted also figure many bits relevant many attacked attempt leaving however many bits attacker defeat following formulas represent probability success given set attempts bits entropy many systems formula_14 thousands millions 64-bit systems numbers typically reach millions least hector marco-gisbert ismael ripoll showed 2014 bypass aslr 64-bit systems less one second certain circumstances 32-bit systems 2004 computer speeds 16 bits address randomization shacham co-workers state ... 16 bits address randomization defeated brute force attack within minutes authors statement depends ability attack application multiple times without delay proper implementations aslr like included grsecurity provide several methods make brute force attacks infeasible one method involves preventing executable executing configurable amount time crashed certain number times android possibly systems implement library load order randomization form aslr randomizes order libraries loaded supplies little entropy approximation number bits entropy supplied per needed library appears yet account varied library sizes actual entropy gained really somewhat higher note attackers usually need one library math complex multiple libraries shown well note case attacker using one library simplification complex formula formula_15 values tend low even large values importantly since attackers typically use c standard library thus one often assume formula_17 however even small number libraries bits entropy gained thus potentially interesting combine library load order randomization vma address randomization gain extra bits entropy note extra bits entropy apply mmap segments libraries attackers may make use several methods reduce entropy present randomized address space ranging simple information leaks attacking multiple bits entropy per attack heap spraying little done possible leak information memory layout using format string vulnerabilities format string functions printf use variable argument list job format specifiers describe argument list looks like way arguments typically passed format specifier moves closer top stack frame eventually return pointer stack frame pointer extracted revealing address vulnerable library address known stack frame completely eliminate library stack randomization obstacle attacker one also decrease entropy stack heap stack typically must aligned 16 bytes smallest possible randomization interval heap must page-aligned typically 4096 bytes attempting attack possible align duplicate attacks intervals nop slide may used shellcode injection string replaced arbitrary number slashes attempting return system number bits removed exactly formula_18 intervals attacked decreases limited due amount data stack heap stack example typically limited grows much less allows although conservative estimate would around 8– corresponding 4– stack stuffing heap hand limited behavior memory allocator case glibc allocations 128 kb created using mmap limiting attackers 5 bits reduction also limiting factor brute forcing although number attacks perform reduced size attacks increased enough behavior could circumstances become apparent intrusion detection systems aslr-protected addresses leaked various side channels removing mitigation utility recent attacks used information leaked cpu branch target predictor buffer btb memory management unit mmu walking page tables clear class aslr attack mitigated benefit aslr reduced eliminated several mainstream general-purpose operating systems implement aslr android 4.0 ice cream sandwich provides address space layout randomization aslr help protect system third party applications exploits due memory-management issues position-independent executable support added android 4.1 android 5.0 dropped non-pie support requires dynamically linked binaries position independent library load ordering randomization accepted android open-source project 26 october 2015 included android 7.0 release dragonfly bsd implementation aslr based upon openbsd model added 2010 default enabled setting sysctl vm.randomize_mmap 1 support aslr appear freebsd 13.0 currently development disabled default apple introduced aslr ios 4.3 released march 2011 kaslr introduced ios 6 randomized kernel base 0x01000000 1+0xrr 0x00200000 0xrr random byte sha1 random data generated iboot 2nd-stage ios boot loader linux kernel enabled weak form aslr default since kernel version 2.6.12 released june 2005 pax exec shield patchsets linux kernel provide complete implementations exec shield patch linux supplies 19 bits stack entropy period 16 bytes 8 bits mmap base randomization period 1 page 4096 bytes places stack base area 8 mb wide containing 524,288 possible positions mmap base area 1 mb wide containing 256 possible positions position-independent executable pie implements random base address main executable binary place since 2003 provides address randomness main executable used shared libraries pie feature use network facing daemons – pie feature used together prelink feature executable prelink tool implements randomization prelink time rather runtime design prelink aims handle relocating libraries dynamic linker allows relocation occur many runs program result real address space randomization would defeat purpose prelinking randomization disabled specific process changing execution domain using personality 2 kernel address space layout randomization kaslr bringing support address space randomization running linux kernel images randomizing kernel code placed boot time merged linux kernel mainline kernel version 3.14 released 30 march 2014 compiled disabled boot time specifying one kernel boot parameters several side-channel attacks x86 processors could leak kernel addresses late 2017 kernel page-table isolation kpti aka kaiser developed defeat attacks however method protect side-channel attacks utilizing collisions branch predictor structures microsoft windows vista released january 2007 later aslr enabled executables dynamic link libraries specifically linked aslr-enabled compatibility enabled default applications typically older software incompatible aslr fully enabled editing registry entry hklm\system\currentcontrolset\control\session manager\memory management\moveimages installing microsoft enhanced mitigation experience toolkit locations heap stack process environment block thread environment block also randomized security whitepaper symantec noted aslr 32-bit windows vista may robust expected microsoft acknowledged weakness implementation host-based intrusion prevention systems wehntrust ozone also offer aslr windows xp windows server 2003 operating systems wehntrust open-source complete details ozone implementation available noted february 2012 aslr 32-bit windows systems prior windows 8 effectiveness reduced low memory situations similar effect also achieved linux research test code caused mac os x 10.7.3 system kernel panic left unclear aslr behavior scenario support aslr userland appeared netbsd 5.0 released april 2009 enabled default netbsd-current april 2016 kernel aslr support amd64 added netbsd-current october 2017 making netbsd first bsd system support kaslr 2003 openbsd became first mainstream operating system support strong form aslr activate default openbsd completed aslr support 2008 added support pie binaries openbsd 4.4 malloc 3 designed improve security taking advantage aslr gap page features implemented part openbsd codice_3 system call detect use-after-free bugs released 2013 openbsd 5.3 first mainstream operating system enable position-independent executables default multiple hardware platforms openbsd 5.7 activated position-independent static binaries static-pie default mac os x leopard 10.5 released october 2007 apple introduced randomization system libraries mac os x lion 10.7 released july 2011 apple expanded implementation cover applications stating address space layout randomization aslr improved applications available 32-bit apps heap memory protections making 64-bit 32-bit applications resistant attack os x mountain lion 10.8 released july 2012 later entire system including kernel well kexts zones randomly relocated system boot aslr introduced solaris beginning solaris 11.1 released october 2012 aslr solaris 11.1 set system-wide per zone per-binary basis side-channel attack utilizing branch target buffer demonstrated bypass aslr protection 2017 attack named aslr⊕cache demonstrated could defeat aslr web browser using javascript
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Operating systems
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ghostbsd ghostbsd unix-like operating system based trueos mate default desktop environment gnome previous desktop environment xfce-desktop community based edition aims easy install ready-to-use easy use project goal combine security privacy stability usability openness freedom free charge prior ghostbsd 18.10 project based freebsd may 2018 announced future versions operating system based trueos beginning ghostbsd 18.10 project moved base freebsd trueos following trueos based ghostbsd releases ghostbsd originally licensed 3-clause bsd license revised bsd license new bsd license modified bsd license 2014 eric turgeon re-licensed ghostbsd 2-clause license simplified bsd license freebsd license ghostbsd contains gpl-licensed software following minimum recommended requirements
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Operating systems
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f5 networks f5 networks inc. global company specializes application services application delivery networking adn f5 technologies focus delivery security performance availability web applications well availability servers cloud resources data storage devices networking components f5 headquartered seattle washington additional development manufacturing sales/marketing offices worldwide known originally load balancing product today f5 product services line expanded things related delivery applications including local load balancing acceleration global dns based load balancing acceleration security web application firewall application authentication access products ddos defense f5 technologies available data center cloud including private public multi-cloud environments based platforms aws microsoft azure google cloud openstack f5 networks originally named f5 labs established 1996 company name inspired 1996 movie twister reference made fastest powerful tornado fujita scale f5 f5 first product launched 1997 load balancer called big-ip server went became overloaded big-ip directed traffic away server servers could handle load june 1999 company initial public offering listed nasdaq stock exchange symbol ffiv 2010 2011 f5 networks fortune list 100 fastest-growing companies company also rated one top ten best-performing stocks p 500 2010 f5 also named best place work online jobs recruiting site glassdoor 2015 2016 competitors included cisco systems 2012 citrix systems radware françois locoh-donou replaced john mcadam president ceo april 3 2017 may 3 2017 f5 announced would move longtime headquarters waterfront near seattle center new downtown seattle skyscraper called f5 tower move occur early 2019 2017 f5 launched dedicated site organization focused gathering global threat intelligence data analyzing application threats publishing related findings dubbed “ f5 labs ” nod company ’ history team continues research application threats publish findings every week benefit broader security community 2019 f5 networks occupies leading position ranking popular companies wikipedia f5 big-ip product family comprises hardware modularized software virtual appliances run f5 tmos operating system depending appliance selected one big-ip product modules added offerings include september 7 2004 f5 networks released version 9.0 big-ip software addition appliances run software version 9.0 also marked introduction company tmos architecture significant enhancements including subsequent releases enhanced performance improves application security supported cloud application deployments f5 describes big-iq framework managing big-ip devices application services irrespective form factors hardware software cloud deployment model on-premises private/public cloud hybrid big-iq supports integration ecosystem participants public cloud providers orchestration engines cloud connectors set open restful apis big-iq uses multi-tenant approach management allows organizations move closer service without concern might affect stability security services fabric silverline cloud-based application service offerings include security services waf ddos protection services 2017 company introduced technologies make f5 capabilities portable across broader range environments including
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Computer security
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unix security unix security refers means securing unix unix-like operating system secure environment achieved design concepts operating systems also vigilant user administrative practices core security feature systems file system permissions files typical unix filesystem permissions set enabling different access file permissions file commonly set using chmod command seen ls command example unix permissions permit different users access file different user groups different permissions file advanced unix filesystems include access control list concept allows permissions granted multiple users groups access control list may used grant permission additional individual users groups example example chacl command linux operating system user sue granted write permission /pvr directory users unix style operating systems often belong managed groups specific access permissions enables users grouped level access system many unix implementations add additional layer security requiring user member wheel user privileges group order access codice_1 command unix unix-like systems account group enables user exact complete control system often known root account access account gained unwanted user results complete breach system root account however necessary administrative purposes security reasons root account seldom used day day purposes sudo program commonly used usage root account closely monitored root access visualised familiar superman stories using following analogy unix many tools improve security used properly users administrators selecting strong password guarding properly probably important things user improve unix security unix systems essential information users stored file codice_2this file keeps track users registered system main definitions passwords correctly hash password also stored place entries codice_2 occupy exactly one line following form example would since users must read access codice_2 file many common tasks codice_5 use codice_2 map uids login names example anyone could also read password hashes users solve problem file codice_7 created store password hashes root read access password shadowing 2nd field password hash replaced x tells system retrieve corresponding user password via codice_7 file codice_7 file often contains values first two fields remaining fields codice_7 file include fields may used improve unix security enforcing password security policy administrators delete old accounts promptly operating systems like software may contain bugs need fixing may enhanced addition new features patching operating system secure manner requires software come trustworthy source altered since packaged common methods verifying operating system patches altered include use cryptographic hash md5 based checksum use read-only media security standpoint specific packaging method rpm package manager format originally red hat linux important use features ensure integrity patch source distributions include ability examine code suspicious content drawback absent accompanying cryptographic hash value user must able perform security analysis code linux distributions use rpm package manager format providing base functionality software updates make use md5 gpg ensure content integrity hash values packaged rpm file verified package installed linux distributions use debian .deb package format providing base functionality software updates make use gpg signatures ensure content integrity signature computed package constructed verified later package installed regardless vendor distribution software distributions provide mechanism verifying software legitimate modified since originally packaged unnecessary system software installed configured system software longer required removed completely possible commands inetd xinetd act super-servers variety network protocols rlogin telnet ftp turning unnecessary services approach usually called proactive security operating systems secure default amongst others free bsd flavours freebsd netbsd openbsd proactively secure example output netstat netbsd 3.0 workstation clearly outlines technique following example bsd system shows machine ssh service listening public network interface computer sendmail listening loopback interface access service may restricted using firewall file system security within unix unix-like systems based 9 permission bits set user group id bits sticky bit total 12 bits permissions apply almost equally filesystem objects files directories devices 9 permission bits divided three groups three bits first group describes permissions file owner second group describes permissions group associated file owner directory containing file third group describes permissions associated process user id file group three bits contains bit indicating read write execute access granted case directories execute access interpreted permission perform filename lookup within directory set user id set group id bits commonly abbreviated set-uid set-gid respectively used change identity process executes file either bits set file set-uid permission bit set cause process executes file temporarily switch effective user id file owner file set-gid permission bit set cause process executes file temporarily switch effective group id file group process may alternate effective user group id inherited file real user group id inherited user logged system provides mechanism process may limit access rights possesses code regions require access rights form security technique known privilege separation improves program security limiting unintended undesirable actions processes directory set-gid permission bit set cause newly created file initial file group value equal file group directory provides mechanism whereby subsystem system mail subsystem create files common file group value set-gid processes within subsystem able read write file sticky bit formally known save text swap bit derives name original purpose originally sticky bit caused process initial memory image stored contiguous image disk drive used store real memory pages use improved performance commonly executed commands making initial memory image readily available modern unix systems longer perform function bit set name preserved nonetheless case files sticky-bit may used system indicate style file locking performed case directories sticky bit prevents process one super-user privileges one effective user id file owner deleting file within directory sticky bit commonly used publicly writable directories various temporary working space directories system root squash reduction access rights remote superuser root using identity authentication local user remote user primarily feature nfs may available systems well problem arises remote file system shared multiple users users belong one multiple groups unix every file folder normally separate permissions read write execute owner normally creator file group owner belongs world users allows restriction read write access authorized users general nfs server must also protected firewall superuser rights ordinary user able change file ownership set arbitrary permissions access protected content even users need root access individual workstations may authorized similar actions shared file system root squash reduces rights remote root making one longer superuser unix like systems root squash option turned /etc/exports file server side implementing root squash authorized superuser performs restricted actions logging nfs server directly mounting exported nfs folder selinux set kernel extensions control access precisely strictly defining files folders network ports resources accessed confined process system mostly used restrict processes database server rather human users also limit processes run root distributions use comparable alternatives like apparmor unix-like operating systems immune microsoft windows viruses binaries created run windows generally wo n't run platforms however many unix like installations provide file storage services microsoft windows clients use samba software may unintentionally become repository viruses stored users common unix servers act mail transfer agents consequently email virus scanning often installed clamav virus scanner available source code form may used scan unix file systems viruses infect operating systems viruses worms target unix-like operating systems fact first computer worm—the morris worm—targeted unix systems network firewall protects systems networks network threats exist opposite side firewall firewalls block access strictly internal services unwanted users cases filter network traffic content iptables current user interface interacting linux kernel netfilter functionality replaced ipchains unix like operating systems may provide native functionality open source firewall products exist detailed information iptables contained elsewhere brief discussion contained order describe iptables may used configure linux firewall netfilter provides state-full packet filter configured according network interface protocol source and/or destination address source and/or destination port state packet network packet traverses several chains time received network interface time accepted host forwarded another host common chains input output forward input chain traversed packets received network interface regardless whether accepted host forwarded another host output chain traversed packets transmitted network interface forward chain traversed packets routed host one network interface another case multi-homed system system one physical network interface built-in chains default policy defines action taken packet reaches end chain packet traversal ends rule matches packet action accept drop reject return simplest iptables firewall consists rules desired service followed rule indicates packets reach rule dropped system permitted example incoming email traffic would rule accepted connections smtp port dropped others rule would required indicated established connections also permitted outgoing connections would receive responses systems following example shows simple packet filter input chain described example addition explicit drop action ensures packets discarded default policy input chain accidentally changed accept less need output chain default policy output chain safely set accept instances may desirable firewall limit certain outgoing connections certain set approved systems known egress filtering may used prevent viruses within firewall escaping systems example may policy network limit outgoing email connections single authorized email servers way combating e-mail spam could achieved following example need include rules example default policy output chain accept note also rule assumes host acting firewall sending email email server good assumption typically firewall system contains minimal amount system code needed act firewall restrictive output chain would contain permissive accept entries services may accessed outside firewall restrictive drop policy chain secure network communication packet sniffing attacks
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Operating systems
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project 6 project 6 simply p6 global surveillance project jointly operated u.s. central intelligence agency cia close cooperation german intelligence agencies bundesnachrichtendienst bnd bundesamt für verfassungsschutz bfv part efforts combat terrorism project includes massive database containing personal information photos license plate numbers internet search histories telephone metadata presumed jihadists headquarters project located neuss germany
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Databases
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explicit congestion notification explicit congestion notification ecn extension internet protocol transmission control protocol defined rfc 3168 2001 ecn allows end-to-end notification network congestion without dropping packets ecn optional feature may used two ecn-enabled endpoints underlying network infrastructure also supports conventionally tcp/ip networks signal congestion dropping packets ecn successfully negotiated ecn-aware router may set mark ip header instead dropping packet order signal impending congestion receiver packet echoes congestion indication sender reduces transmission rate detected dropped packet rather responding properly ignoring bits outdated faulty network equipment historically dropped mangled packets ecn bits set measurements suggested fraction web servers public internet setting ecn prevents network connections reduced less 1 passive support existed ubuntu linux since 12.04 windows server since 2012 passive support popular websites increased 8.5 2012 70 may 2017 adoption across internet requires clients actively request ecn june 2015 apple announced ecn enabled default supported future products help drive adoption ecn signaling industry-wide ecn requires specific support internet layer transport layer following reasons without ecn congestion indication echo achieved indirectly detection lost packets ecn congestion indicated setting ecn field within ip packet ce echoed back receiver transmitter setting proper bits header transport protocol example using tcp congestion indication echoed back setting ece bit ecn uses two least significant right-most bits diffserv field ipv4 ipv6 header encode four different code points endpoints support ecn mark packets ect 0 ect 1 packet traverses active queue management aqm queue e.g. queue uses random early detection red experiencing congestion corresponding router supports ecn may change code point codice_5 instead dropping packet act referred “ marking ” purpose inform receiving endpoint impending congestion receiving endpoint congestion indication handled upper layer protocol transport layer protocol needs echoed back transmitting node order signal reduce transmission rate ce indication handled effectively upper layer protocol supports ecn used conjunction upper layer protocols tcp support congestion control method echoing ce indication transmitting endpoint tcp supports ecn using two flags tcp header first ecn-echo ece used echo back congestion indication i.e signal sender reduce amount information sends second congestion window reduced cwr acknowledge congestion-indication echoing received use ecn tcp connection optional ecn used must negotiated connection establishment including suitable options syn syn-ack segments ecn negotiated tcp connection sender indicates ip packets carry tcp segments connection carrying traffic ecn capable transport marking ect code point allows intermediate routers support ecn mark ip packets ce code point instead dropping order signal impending congestion upon receiving ip packet congestion experienced code point tcp receiver echoes back congestion indication using ece flag tcp header endpoint receives tcp segment ece bit reduces congestion window packet drop acknowledges congestion indication sending segment cwr bit set node keeps transmitting tcp segments ece bit set receives segment cwr bit set see affected packets tcpdump use filter predicate codice_6 since transmission control protocol tcp perform congestion control control packets pure acks syn fin segments control packets usually marked ecn-capable 2009 proposal suggests marking syn-ack packets ecn-capable improvement known ecn+ shown provide dramatic improvements performance short-lived tcp connections ecn also defined transport layer protocols perform congestion control notably dccp stream control transmission protocol sctp general principle similar tcp although details on-the-wire encoding differ principle possible use ecn protocols layered udp however udp requires congestion control performed application current networking apis give access ecn bits since ecn effective combination active queue management aqm policy benefits ecn depend precise aqm used observations however appear hold across different aqms expected ecn reduces number packets dropped tcp connection avoiding retransmission reduces latency especially jitter effect drastic tcp connection single outstanding segment able avoid rto timeout often case interactive connections remote logins transactional protocols http requests conversational phase smtp sql requests effects ecn bulk throughput less clear modern tcp implementations fairly good resending dropped segments timely manner sender window large use ecn found detrimental performance highly congested networks using aqm algorithms never drop packets modern aqm implementations avoid pitfall dropping rather marking packets high load many modern implementations tcp/ip protocol suite support ecn however usually ship ecn disabled windows versions since windows server 2008 windows vista support ecn tcp since windows server 2012 enabled default windows server versions data center transmission control protocol dctcp used previous windows versions non-server versions disabled default ecn support enabled using shell command freebsd 8.0 netbsd 4.0 implement ecn support tcp activated sysctl interface setting 1 value parameter likewise sysctl used openbsd since version 2.4.20 linux kernel released november 2002 linux supports three working modes ecn tcp configured sysctl interface setting parameter one following values beginning version 4.1 linux kernel released june 2015 mechanism specified rfc 3168 section 6.1.1.1 enabled default ecn enabled value 1 fallback mechanism attempts ecn connectivity initial setup outgoing connections graceful fallback transmissions without ecn capability mitigating issues ecn-intolerant hosts firewalls mac os x 10.5 10.6 implement ecn support tcp controlled using boolean sysctl variables first variable enables ecn incoming connections already ecn flags set second one tries initiate outgoing connections ecn enabled variables default set enable respective behavior june 2015 apple inc. announced os x 10.11 released later year would ecn turned default never happened macos sierra ecn enabled 50 percent tcp sessions june 2015 apple inc. announced ios 9 next version ios would support ecn turned default tcp ecn negotiation enabled 5 randomly selected connections wi-fi ethernet ios 9 50 randomly selected connections wi-fi ethernet cellular carriers ios 10 100 ios 11 solaris kernel supports three states ecn tcp default behavior solaris 11 full ecn usage activated via since ecn marking routers dependent form active queue management routers must configured suitable queue discipline order perform ecn marking cisco ios routers perform ecn marking configured wred queuing discipline since version 12.2 8 t. linux routers perform ecn marking configured one red gred queue disciplines explicit ecn parameter using sfb discipline using codel fair queuing fq_codel discipline cake queuing discipline modern bsd implementations freebsd netbsd openbsd support ecn marking altq queueing implementation number queuing disciplines notably red blue freebsd 11 included codel pie fq-codel fq-pie queuing disciplines implementation ipfw/dummynet framework ecn marking capability data center transmission control protocol data center tcp dctcp utilizes ecn enhance transmission control protocol congestion control algorithm used data center networks whereas standard tcp congestion control algorithm able detect presence congestion dctcp using ecn able gauge extent congestion dctcp modifies tcp receiver always relay exact ecn marking incoming packets cost ignoring function meant preserve signalling reliability makes dctcp sender vulnerable loss acks receiver mechanism detect cope algorithms provide equivalent better receiver feedback reliable approach active research topic
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Internet protocols
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chartbeat chartbeat technology company provides data analytics global publishers company started 2009 headquartered new york city us saas company integrates code websites publishers media companies news organizations track audience engagement loyalty metrics make decisions content publish promote web sites august 2010 company spun betaworks separate entity chartbeat praised criticized alternative google analytics real-time data betaworks launched chartbeat april 2009 real-time web analytics tool said publishers could use react quickly changes user behavior time google analytics offer real-time data launch chartbeat part broader strategy betaworks capitalize growth real-time stream-based social web betaworks also invested twitter tumblr bit.ly tweetdeck august 2010 company spun betaworks separate entity july 2011 chartbeat launched newsbeat version service news sites february 2016 founding ceo tony haile resigned company seven years ceo long time coo john saroff named successor october 2017 chartbeat made updates user experience design including rebrand flagship product chartbeat publishing
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Web technology
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robert lipka robert stephen lipka june 16 1945 – july 5 2013 former army clerk national security agency nsa 1997 pleaded guilty conspiracy commit espionage sentenced 18 years prison arrested 30 years betrayal statute limitations espionage robert lipka assigned national security agency intelligence analyst 1964 19-year-old u.s. army soldier worked central communications room 1964–1967 responsible removing disseminating highly classified documents throughout agency despite junior rank lipka held high security clearance access diverse array highly classified documents september 1965 lipka presented soviet embassy 16th street walk-in volunteer spy announced responsible shredding highly classified documents next two years made contact residency around fifty times using variety skilled tradecraft according handler time former kgb general oleg danilovich kalugin young soldier lipka ... involved shredding destroying nsa documents could supply us wealth material goes say lipka gave whatever got hands often little idea turning lipka compromised daily weekly top-secret reports white house information us troop movements throughout world communications among nato allies two years lipka supplied kgb top-secret information received payment 27,000 kalugin claims lipka used money received around 500 1,000 per package delivered finance college education however lipka regularly complained deserved money threatened break contact demand met august 1967 lipka made good threat left nsa end military service order attend millersville university pennsylvania order discourage attempts kgb recontact lipka sent final message claiming double agent us intelligence along according vasili mitrokhin kgb knew lie high importance classified documents lipka provided residency illegals non diplomatic cover handlers tried renew contact lipka intermittently least another 11 years though without success similar john anthony walker case lipka ex-wife made accusations treason fbi 1993 armed accusations revelations kalugin memoir information separate investigation implicating lipka fbi decided use false flag operation catch fbi agent dmitri droujinsky contacted lipka posing gru officer based washington named sergei nikitin lipka told nikitin still owed money course four meetings nikitin gave lipka 10,000 lengthy investigation lipka admitted spy nsa february 1996 arrested home millersville pa charged handing classified documents soviet union statute limitations espionage cases matter lipka ceased spying soviet union three decades arrest may 1997 lipka accepted plea deal avoid trial could resulted life sentence courtroom philadelphia inquirer reported lipka exploded tears confessed handed classified information kgb agents sentenced september 1997 18 years prison 10,000 fine additional reimbursement fbi 10,000 given nikitin according federal bureau prisons lipka released december 8 2006 july 5 2013 robert lipka died meadville pa age 68 remains cremated john w. whiteside iii fool mate true story espionage national security agency 2014
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Computer security
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composite artifact colors composite artifact colors designation commonly used address several graphic modes 1970s 1980s home computers machines connected ntsc tv monitor composite video outputs video signal encoding allowed extra colors displayed manipulating pixel position screen limited machine hardware color palette though modern tvs might work well mode used mainly games since limited display horizontal resolution normal mostly used ibm pc cga graphics trs-80 color computer apple ii computers also possible atari 8-bit limitations composite video regarding horizontal resolution also exploited systems adjacent pixel values got averaged horizontally producing solid colors generating transparency effects pal displays ntsc 4.43 ones effect n't generate new colors rather mix adjacent horizontal pixel values however depending pal system used results vary pal pal n used color artifacts seen ntsc might also possible higher resolution video connection used graphics displayed dither patterns machines zx spectrum mega drive took advantage situation using ibm color graphics adapter cga ntsc tv-out separation luminance chrominance imperfect yielding cross-color artifacts color smearing especially problem 80-column text reason text graphics modes described exists twice normal color version monochrome version monochrome version mode turns ntsc color decoding viewing monitor completely resulting black-and-white picture also color bleeding hence sharper picture rgbi monitors two versions mode identical exception 320×200 graphics mode monochrome version produces third palette described however programmers learned flaw could turned asset distinct patterns high-resolution dots would smear consistent areas solid colors thus allowing display completely new colors since new colors result cross-color artifacting often called artifact colors standard 320×200 four-color 640×200 color-on-black graphics modes could used technique resulting screens would usable resolution 160×200 16 colors trs-80 color computer 256×192 two color graphics mode uses four colors due quirk ntsc television system possible reliably display 256 dots across screen due limitations ntsc signal phase relationship vdg clock colorburst frequency first colorset green black dots available alternating columns green black distinct appear muddy green color however one switches white black colorset instead muddy gray expected result either orange blue reversing order alternating dots give opposite color effect mode becomes 128×192 4 color graphics mode black orange blue white available apple ii created color graphics exploiting similar effect coco games used mode colors available useful ones provided hardware 4 color modes vdg internally power either rising falling edge clock bit patterns represent orange blue predictable coco games start title screen asks user press reset button colors correct coco 3 fixes clock-edge problem always user holds f1 key reset choose color set coco 3 analog rgb monitor black white dot patterns artifact see one uses tv composite monitor patch games use hardware 128×192 four color mode gime chip allows color choices mapped users pal countries see green purple stripes instead solid red blue colors readers rainbow hot coco magazine learned use poke commands switch 6847 vdg one artifact modes extended color basic continues operate though still displaying one 128x192 four-color modes thus entire set extended color basic graphics commands used artifact colors users developed set 16 artifact colors using 4×2 pixel matrix use poke commands also make colors available graphics commands although colors drawn one horizontal line time interesting artworks produced effects especially since coco max art package provides palette colors resulting 16 color palette color graphics apple ii series uses quirk ntsc television signal standard made color display relatively easy inexpensive implement apple ii display provides two pixels per ntsc subcarrier cycle color burst reference signal computer attached color display display green showing one alternating pattern pixels magenta opposite pattern alternating pixels white placing two pixels next later blue orange became available tweaking offset pixels half pixel-width relation color-burst signal high-resolution display offers colors simply compressing narrower pixels subcarrier cycle coarse low-resolution graphics display mode works differently output pattern dots per pixel offer color options patterns stored character generator rom replaces text character bit patterns computer switched low-res graphics mode text mode low-res graphics mode uses memory region circuitry used graphics 8 mode atari 8-bit computers using color television interface adaptor ctia chip designed display black white resolution 320×192 programmers found using artifact colors blue red also used mode software on-line systems wizard princess use feature display four colors atari began shipping computers improved graphic television interface adaptor gtia users found programs displayed incorrect colors needed updates many high-profile game titles offers graphics optimized composite color monitors ultima ii first game game series ported ibm pc uses cga composite graphics king quest also innovative use 16-color graphics titles include microsoft decathlon king quest ii king quest iii using composite connection pal tv system generate new colors instead horizontal blurring effect given different bandwidths pal broadcast systems pal-m pal-n pal-b etc.. actual effect intensity vary effect pronounced higher display resolutions used exploited game artists machines using dithering patterns one notable example mega drive takes full advantage simulate transparency effects earlier machine zx spectrum uses effect blend colors simulate half bright variations basic 8 color palette home computers like atari st commodore amiga also graphics prepared dithering techniques take advantage composite tv connections regarding amiga special hold-and-modify particularly suited displaying high color tv-like images taking full advantage horizontal blurring
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Computer architecture
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epon protocol coax epon protocol coax epoc refers transparent extension ethernet passive optical network epon cable operator hybrid fiber-coax hfc network service provider perspective use coax portion network transparent epon protocol operation optical line terminal olt thereby creating unified scheduling management quality service qos environment includes optical coax portions network ieee 802.3 ethernet working group initiated standards process creation epoc study group november 2011 epoc adds family ieee 802.3 ethernet first mile efm standards institute electrical electronics engineers ieee 802.3 standards committee published standards symmetric 1gbit/s epon network originally published september 2004 ieee 802.3ah-2004 10gbit/s epon network permitting symmetric 10gbit/s asymmetric 10gbit/s downstream 1gbit/s upstream originally published june 2009 ieee 802.3av-2009 also known 10g-epon call interest cfi group process initiated may 2011 broadcom receiving requests initiating epoc standardization ieee chinese cable operators also north american cable operators many companies became involved cfi creation consensus process according cfi materials representatives following companies supported formation study group alcatel-lucent aurora networks bright house networks broadcom cogeco cable inc. cablelabs comcast cox networks dell fiberhome telecommunication technologies harmonic inc. hewlett-packard high speed design huawei neophotonics pmc-sierra qualcomm sumitomo electric industries technical working committee china radio tv association time warner cable wuhan yangtze optical technologies co. ltd. zte november 2011 epon phy coax cfi presented ieee 802.3 working group plenary creation epoc study group sg approved may 2012 epoc study group completed draft project authorization request par 5 criteria responses set objectives work materials require review approval ieee 802.3 working group ieee 802 lan/man standards committee lmsc ieee new standards committee nescom upon receiving approval epoc study group transition epoc task force tf begin work leads directly creating draft standard 30 august 2012 ieee-sa approved par permitting ieee 802.3 working group charter ieee p802.3bn task force ieee 802.3 standards apply media access control mac sublayer physical sublayer specifications respective management epon ieee 802.3 defined separately service provider mac phy called optical line terminal olt subscriber mac physical sublayer called optical network unit onu medium interconnecting olt onu fiber optical cable two wavelengths defined full-duplex operation one continuous downstream channel operation olt transmitting one onus another upstream burst mode channel operation permits olt-controlled time-division sharing upstream channel amongst onus pon similarly epoc architecture consists service provider coax line terminal clt subscriber coax network unit cnu intent clt mac sublayer olt mac sublayer cnu mac sublayer onu mac sublayer optical physical sublayer fiber optical media replaced coax physical sublayer coaxial distribution network cxdn media coax media downstream upstream communication channels utilize radio frequency rf spectrum assigned made available cable operator coax network case coax network medium dependent interface mdi typically industry standard f connector ieee 802.3 standards describe implementations system solutions use olt clt onu cnu standard apply respective mac physical sublayers two system models discussion ieee 802.3 epoc study group first direct output ieee 802.3 epoc standardization effort i.e. clt one cnus interconnected coaxial distribution network second enabled future epoc standard outside scope ieee 802.3 working group traditional epon deployment consisting olt device one onu devices attached pon one new devices referred functionally optical coax media converter cmc attach one side pon cxdn associated cnus communications coax media follows epoc standard intent second model permit olt transparently manage collection onu cnu devices similar fashion e.g unified epon management scheduling quality service second model viewed extending ethernet pon onto coax given likely shorter reach coax clt developed likely used fttb applications clt building epoc tenants second possibility outside plant e.g strand mounted cabinet based clt would fttc
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Internet protocols
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metadata removal tool metadata removal tool metadata scrubber type privacy software built protect privacy users removing potentially privacy-compromising metadata files shared others e.g. sending e-mail attachments posting web metadata removal tools also commonly used reduce overall sizes files particularly image files posted web example small image website may contain metadata including thumbnail image easily contain much metadata image data thus removal metadata halve file size metadata found many types files documents spreadsheets presentations images audio files include information details file authors file creation modification dates location gps document revision history thumbnail images comments since metadata sometimes clearly visible authoring applications depending application settings risk user unaware existence forget file shared private confidential information inadvertently exposed purpose metadata removal tools minimize risk data leakage metadata removal tools exist today divided four groups
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Computer security
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taum system taum traduction automatique à l'université de montréal name research group set université de montréal 1965 research done 1968 1980 gave birth taum-73 taum-meteo machine translation prototypes using q-systems programming language created alain colmerauer among first attempts perform automatic translation linguistic analysis prototypes never used actual production taum-meteo name erroneously used many years designate meteo system subsequently developed john chandioux
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Computational linguistics
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stub distributed computing stub distributed computing piece code converts parameters passed client server remote procedure call rpc main idea rpc allow local computer client remotely call procedures different computer server client server use different address spaces parameters used function procedure call converted otherwise values parameters could used pointers parameters one computer memory would point different data computer client server may also use different data representations even simple parameters e.g. big-endian versus little-endian integers stubs perform conversion parameters remote procedure call looks like local function call remote computer stub libraries must installed client server side client stub responsible conversion marshalling parameters used function call deconversion results passed server execution function server skeleton stub server side responsible deconversion parameters passed client conversion results execution function stubs generated one two ways server program implements procedure interface said export interface client program calls procedures interface said import interface writing distributed application programmer first writes interface definition using idl programmers write client program imports interface server program exports interface interface definition processed using idl compiler generate components combined client server programs without making changes existing compilers particular interface procedure interface compiler generate appropriate marshalling unmarshalling operations stub procedure header file supports data types interface definition header file included source files client server programs client stub procedures compiled linked client program server stub procedures compiled linked server program idl compiler designed process interface definitions use different languages enabling clients servers written different languages communicate using remote procedure calls achieve goal semantics transparency designers made rpc look like lpc using concept stubs hide actual rpc implementation programs interface underlying rpc system
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Distributed computing architecture
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sandstorm enterprises sandstorm enterprises american computer security software vendor founded 1998 simson garfinkel james van bokkelen gene spafford dan geer january 2010 purchased niksun inc. sandstorm located greater boston area sandstorm major products phonesweep first commercial multi-line telephone scanner war dialer introduced 1998 netintercept commercial network forensics tool introduced 2001 designed second-generation network analysis tool netintercept operated primarily level tcp udp data streams application-layer objects transport 2002 sandstorm purchased lanwatch commercial packet-oriented lan monitor originally developed ftp software lanwatch sold separate product much functionality used netintercept display individual packets 2019 phonesweep product still sold supported niksun core parts netintercept product also still exist incorporated niksun netdetector network forensics product line
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Computer security
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hikarunix hikarunix discontinued linux distribution live cd format x86 architecture based damn small linux last updated 2005 name portmanteau name manga anime series hikaru go linux operating system kernel hikarunix based unix-like operating system hikarunix intended provide complete ultra-portable environment study playing game go complete beginner mori interactive way go included addition several books pdf form well complete offline copy sensei library intermediate players take advantage comprehensive joseki library collection 9500 challenging problems work called gogrinder expert use many online go clients study annotated games go masters even games analyzed contained within os fit mini- regular-sized cd installed harddrive put onto usb memory stick go enthusiasts use hikarunix everywhere
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Operating systems
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iphone dev team iphone dev team group engineers ios formerly iphone os community developed several tools enable use applications authorized apple inc iphone ipod touch ipad enable use iphone gsm carriers contracted apple applications provided owners ability sidestep limitations placed devices manufacturer allowing activities deep customization easy international roaming group tools became emblematic activities termed jailbreaking sim unlocking respectively extent electronic frontier foundation made primary example used petition create dmca anti-circumvention exemption jailbreaking apple executive greg joswiak vice president iphone product marketing quoted countering comment petition products maintained iphone dev team include
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Computer security
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fips 199 fips 199 federal information processing standard publication 199 standards security categorization federal information information systems united states federal government standard establishes security categories information systems used federal government one component risk assessment fips 199 fips 200 mandatory security standards required fisma fips 199 requires federal agencies assess information systems categories confidentiality integrity availability rating system low moderate high impact category severe rating category becomes information system overall security categorization
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Computer security
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bing webmaster tools bing webmaster tools previously bing webmaster center free service part microsoft bing search engine allows webmasters add websites bing index crawler service also offers tools webmasters troubleshoot crawling indexing website sitemap creation submission ping tools website statistics consolidation content submission new content community resources bing webmaster center contains following tools features support webmasters access data manage websites bing
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Web technology
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jean-marie hullot jean-marie hullot february 16 1954 – june 17 2019 french computer scientist programmer authored important programs original macintosh nextstep mac os x platforms include sos interface mac later became interface builder nextstep 1985 later still evolved important part mac os x also led ical isync development teams mac os x 2002 1981 jean-marie hullot received ph.d. computer science university paris orsay adviser gérard huet researcher inria 1979 1985 joined next 1996 co-founded realnames url translation service closed 2002 worked cto application division apple inc. 2001 2005 president ceo fotopedia collaborative photo encyclopaedia died june 17 2019
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Operating systems
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intruder detection information security intruder detection process detecting intruders behind attacks unique persons technique tries identify person behind attack analyzing computational behaviour concept sometimes confused intrusion detection also known ids techniques art detecting intruder actions intruder detection systems try detect attacking system analyzing computational behaviour biometric behaviour keystroke dynamics paramount intruder detection techniques parameter classified real 'behavioural biometric pattern keystroke dynamics analyze times keystrokes issued computer keyboard cellular phone keypad searching patterns first techniques used statistics probability concepts like 'standard deviations 'mean later approaches use data mining neural networks support vector machine etc earlier works reference concept intruder authentication intruder verification intruder classification si6 project one first projects deal full scope concept confusion spanish translation 'intrusion detection system also known ids people translate 'sistemas de detección de intrusiones others translate 'sistemas de detección de intrusos former correct
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Computer security
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nhttpd nhttpd open-source web server also known nostromo web server designed marcus glocker runs single process handles normal concurrent connections select calls efficiency demanding connections directory listings cgi execution forks supports http/1.1 cgi/1.1 basic access authentication ssl ipv6 custom responses aliases virtual hosts security measures include running setuid chrooting public access controlled using world readable flags cgi execution world executable flags file system permissions
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Web technology
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automatic summarization automatic summarization process shortening text document software order create summary major points original document technologies make coherent summary take account variables length writing style syntax automatic data summarization part machine learning data mining main idea summarization find subset data contains information entire set techniques widely used industry today search engines example others include summarization documents image collections videos document summarization tries create representative summary abstract entire document finding informative sentences image summarization system finds representative important i.e salient images surveillance videos one might want extract important events uneventful context two general approaches automatic summarization extraction abstraction extractive methods work selecting subset existing words phrases sentences original text form summary contrast abstractive methods build internal semantic representation use natural language generation techniques create summary closer human might express summary might include verbal innovations research date focused primarily extractive methods appropriate image collection summarization video summarization summarization task automatic system extracts objects entire collection without modifying objects examples include keyphrase extraction goal select individual words phrases tag document document summarization goal select whole sentences without modifying create short paragraph summary similarly image collection summarization system extracts images collection without modifying images extraction techniques merely copy information deemed important system summary example key clauses sentences paragraphs abstraction involves paraphrasing sections source document general abstraction condense text strongly extraction programs harder develop require use natural language generation technology growing field work done abstractive summarization creating abstract synopsis like human majority summarization systems extractive selecting subset sentences place summary machine learning techniques closely related fields information retrieval text mining successfully adapted help automatic summarization apart fully automated summarizers fas systems aid users task summarization mahs machine aided human summarization example highlighting candidate passages included summary systems depend post-processing human hams human aided machine summarization broadly two types extractive summarization tasks depending summarization program focuses first generic summarization focuses obtaining generic summary abstract collection whether documents sets images videos news stories etc. second query relevant summarization sometimes called query-based summarization summarizes objects specific query summarization systems able create query relevant text summaries generic machine-generated summaries depending user needs example summarization problem document summarization attempts automatically produce abstract given document sometimes one might interested generating summary single source document others use multiple source documents example cluster articles topic problem called multi-document summarization related application summarizing news articles imagine system automatically pulls together news articles given topic web concisely represents latest news summary image collection summarization another application example automatic summarization consists selecting representative set images larger set images summary context useful show representative images results image collection exploration system video summarization related domain system automatically creates trailer long video also applications consumer personal videos one might want skip boring repetitive actions similarly surveillance videos one would want extract important suspicious activity ignoring boring redundant frames captured high level summarization algorithms try find subsets objects like set sentences set images cover information entire set also called core-set algorithms model notions like diversity coverage information representativeness summary query based summarization techniques additionally model relevance summary query techniques algorithms naturally model summarization problems textrank pagerank submodular set function determinantal point process maximal marginal relevance mmr etc task following given piece text journal article must produce list keywords key phrase capture primary topics discussed text case research articles many authors provide manually assigned keywords text lacks pre-existing keyphrases example news articles rarely keyphrases attached would useful able automatically number applications discussed consider example text news article keyphrase extractor might select army corps engineers president bush new orleans defective flood-control pumps keyphrases pulled directly text contrast abstractive keyphrase system would somehow internalize content generate keyphrases appear text closely resemble human might produce political negligence inadequate protection floods abstraction requires deep understanding text makes difficult computer system keyphrases many applications enable document browsing providing short summary improve information retrieval documents keyphrases assigned user could search keyphrase produce reliable hits full-text search employed generating index entries large text corpus depending different literature definition key terms words phrases keyword extraction highly related theme beginning work turney many researchers approached keyphrase extraction supervised machine learning problem given document construct example unigram bigram trigram found text though text units also possible discussed compute various features describing example e.g. phrase begin upper-case letter assume known keyphrases available set training documents using known keyphrases assign positive negative labels examples learn classifier discriminate positive negative examples function features classifiers make binary classification test example others assign probability keyphrase instance text might learn rule says phrases initial capital letters likely keyphrases training learner select keyphrases test documents following manner apply example-generation strategy test documents run example learner determine keyphrases looking binary classification decisions probabilities returned learned model probabilities given threshold used select keyphrases keyphrase extractors generally evaluated using precision recall precision measures many proposed keyphrases actually correct recall measures many true keyphrases system proposed two measures combined f-score harmonic mean two f 2 pr p r matches proposed keyphrases known keyphrases checked stemming applying text normalization designing supervised keyphrase extraction system involves deciding several choices apply unsupervised first choice exactly generate examples turney others used possible unigrams bigrams trigrams without intervening punctuation removing stopwords hulth showed get improvement selecting examples sequences tokens match certain patterns part-of-speech tags ideally mechanism generating examples produces known labeled keyphrases candidates though often case example use unigrams bigrams trigrams never able extract known keyphrase containing four words thus recall may suffer however generating many examples also lead low precision also need create features describe examples informative enough allow learning algorithm discriminate keyphrases non- keyphrases typically features involve various term frequencies many times phrase appears current text larger corpus length example relative position first occurrence various boolean syntactic features e.g. contains caps etc turney paper used 12 features hulth uses reduced set features found successful kea keyphrase extraction algorithm work derived turney ’ seminal paper end system need return list keyphrases test document need way limit number ensemble methods i.e. using votes several classifiers used produce numeric scores thresholded provide user-provided number keyphrases technique used turney c4.5 decision trees hulth used single binary classifier learning algorithm implicitly determines appropriate number examples features created need way learn predict keyphrases virtually supervised learning algorithm could used decision trees naive bayes rule induction case turney genex algorithm genetic algorithm used learn parameters domain-specific keyphrase extraction algorithm extractor follows series heuristics identify keyphrases genetic algorithm optimizes parameters heuristics respect performance training documents known key phrases another keyphrase extraction algorithm textrank supervised methods nice properties like able produce interpretable rules features characterize keyphrase also require large amount training data many documents known keyphrases needed furthermore training specific domain tends customize extraction process domain resulting classifier necessarily portable turney results demonstrate unsupervised keyphrase extraction removes need training data approaches problem different angle instead trying learn explicit features characterize keyphrases textrank algorithm exploits structure text determine keyphrases appear central text way pagerank selects important web pages recall based notion prestige recommendation social networks way textrank rely previous training data rather run arbitrary piece text produce output simply based text intrinsic properties thus algorithm easily portable new domains languages textrank general purpose graph-based ranking algorithm nlp essentially runs pagerank graph specially designed particular nlp task keyphrase extraction builds graph using set text units vertices edges based measure semantic lexical similarity text unit vertices unlike pagerank edges typically undirected weighted reflect degree similarity graph constructed used form stochastic matrix combined damping factor random surfer model ranking vertices obtained finding eigenvector corresponding eigenvalue 1 i.e. stationary distribution random walk graph vertices correspond want rank potentially could something similar supervised methods create vertex unigram bigram trigram etc however keep graph small authors decide rank individual unigrams first step include second step merges highly ranked adjacent unigrams form multi-word phrases nice side effect allowing us produce keyphrases arbitrary length example rank unigrams find advanced natural language processing get high ranks would look original text see words appear consecutively create final keyphrase using four together note unigrams placed graph filtered part speech authors found adjectives nouns best include thus linguistic knowledge comes play step edges created based word co-occurrence application textrank two vertices connected edge unigrams appear within window size n original text n typically around 2–10 thus natural language might linked text nlp natural processing would also linked would appear string n words edges build notion text cohesion idea words appear near likely related meaningful way recommend reader since method simply ranks individual vertices need way threshold produce limited number keyphrases technique chosen set count user-specified fraction total number vertices graph top vertices/unigrams selected based stationary probabilities post- processing step applied merge adjacent instances unigrams result potentially less final keyphrases produced number roughly proportional length original text initially clear applying pagerank co-occurrence graph would produce useful keyphrases one way think following word appears multiple times throughout text may many different co-occurring neighbors example text machine learning unigram learning might co-occur machine supervised un-supervised semi-supervised four different sentences thus learning vertex would central hub connects modifying words running pagerank/textrank graph likely rank learning highly similarly text contains phrase supervised classification would edge supervised classification classification appears several places thus many neighbors importance would contribute importance supervised ends high rank selected one top unigrams along learning probably classification final post-processing step would end keyphrases supervised learning supervised classification short co-occurrence graph contain densely connected regions terms appear often different contexts random walk graph stationary distribution assigns large probabilities terms centers clusters similar densely connected web pages getting ranked highly pagerank approach also used document summarization considered like keyphrase extraction document summarization aims identify essence text real difference dealing larger text units—whole sentences instead words phrases getting details summarization methods mention summarization systems typically evaluated common way using so-called rouge recall-oriented understudy gisting evaluation measure recall-based measure determines well system-generated summary covers content present one human-generated model summaries known references recall-based encourage systems include important topics text recall computed respect unigram bigram trigram 4-gram matching example rouge-1 computed division count unigrams reference appear system count unigrams reference summary multiple references rouge-1 scores averaged rouge based content overlap determine general concepts discussed automatic summary reference summary determine result coherent sentences flow together sensible manner high-order n-gram rouge measures try judge fluency degree note rouge similar bleu measure machine translation bleu precision- based translation systems favor accuracy promising line document summarization adaptive document/text summarization idea adaptive summarization involves preliminary recognition document/text genre subsequent application summarization algorithms optimized genre first summarizes perform adaptive summarization created supervised text summarization much like supervised keyphrase extraction basically collection documents human-generated summaries learn features sentences make good candidates inclusion summary features might include position document i.e. first sentences probably important number words sentence etc main difficulty supervised extractive summarization known summaries must manually created extracting sentences sentences original training document labeled summary summary typically people create summaries simply using journal abstracts existing summaries usually sufficient sentences summaries necessarily match sentences original text would difficult assign labels examples training note however natural summaries still used evaluation purposes since rouge-1 cares unigrams duc 2001 2002 evaluation workshops tno developed sentence extraction system multi-document summarization news domain system based hybrid system using naive bayes classifier statistical language models modeling salience although system exhibited good results researchers wanted explore effectiveness maximum entropy classifier meeting summarization task known robust feature dependencies maximum entropy also applied successfully summarization broadcast news domain unsupervised approach summarization also quite similar spirit unsupervised keyphrase extraction gets around issue costly training data unsupervised summarization approaches based finding centroid sentence mean word vector sentences document sentences ranked regard similarity centroid sentence principled way estimate sentence importance using random walks eigenvector centrality lexrank algorithm essentially identical textrank use approach document summarization two methods developed different groups time lexrank simply focused summarization could easily used keyphrase extraction nlp ranking task lexrank textrank graph constructed creating vertex sentence document edges sentences based form semantic similarity content overlap lexrank uses cosine similarity tf-idf vectors textrank uses similar measure based number words two sentences common normalized sentences lengths lexrank paper explored using unweighted edges applying threshold cosine values also experimented using edges weights equal similarity score textrank uses continuous similarity scores weights algorithms sentences ranked applying pagerank resulting graph summary formed combining top ranking sentences using threshold length cutoff limit size summary worth noting textrank applied summarization exactly described lexrank used part larger summarization system mead combines lexrank score stationary probability features like sentence position length using linear combination either user-specified automatically tuned weights case training documents might needed though textrank results show additional features absolutely necessary another important distinction textrank used single document summarization lexrank applied multi-document summarization task remains cases—only number sentences choose grown however summarizing multiple documents greater risk selecting duplicate highly redundant sentences place summary imagine cluster news articles particular event want produce one summary article likely many similar sentences would want include distinct ideas summary address issue lexrank applies heuristic post-processing step builds summary adding sentences rank order discards sentences similar ones already placed summary method used called cross-sentence information subsumption csis methods work based idea sentences recommend similar sentences reader thus one sentence similar many others likely sentence great importance importance sentence also stems importance sentences recommending thus get ranked highly placed summary sentence must similar many sentences turn also similar many sentences makes intuitive sense allows algorithms applied arbitrary new text methods domain-independent easily portable one could imagine features indicating important sentences news domain might vary considerably biomedical domain however unsupervised recommendation -based approach applies domain multi-document summarization automatic procedure aimed extraction information multiple texts written topic resulting summary report allows individual users professional information consumers quickly familiarize information contained large cluster documents way multi-document summarization systems complementing news aggregators performing next step road coping information overload multi-document summarization may also done response question multi-document summarization creates information reports concise comprehensive different opinions put together outlined every topic described multiple perspectives within single document goal brief summary simplify information search cut time pointing relevant source documents comprehensive multi-document summary contain required information hence limiting need accessing original files cases refinement required automatic summaries present information extracted multiple sources algorithmically without editorial touch subjective human intervention thus making completely unbiased multi-document extractive summarization faces problem potential redundancy ideally would like extract sentences central i.e. contain main ideas diverse i.e. differ one another lexrank deals diversity heuristic final stage using csis systems used similar methods maximal marginal relevance mmr trying eliminate redundancy information retrieval results general purpose graph-based ranking algorithm like page/lex/textrank handles centrality diversity unified mathematical framework based absorbing markov chain random walks absorbing random walk like standard random walk except states absorbing states act black holes cause walk end abruptly state algorithm called grasshopper addition explicitly promoting diversity ranking process grasshopper incorporates prior ranking based sentence position case summarization state art results multi-document summarization however obtained using mixtures submodular functions methods achieved state art results document summarization corpora duc 04 07 similar results also achieved use determinantal point processes special case submodular functions duc-04 new method multi-lingual multi-document summarization avoids redundancy works simplifying generating ideograms represent meaning sentence document evaluates similarity qualitatively comparing shape position said ideograms recently developed tool use word frequency need training preprocessing kind works generating ideograms represent meaning sentence summarizes using two user-supplied parameters equivalence two sentences considered equivalent relevance long desired summary simplish simplifying summarizing tool performs automatic multi-lingual multi-document summarization idea submodular set function recently emerged powerful modeling tool various summarization problems submodular functions naturally model notions coverage information representation diversity moreover several important combinatorial optimization problems occur special instances submodular optimization example set cover problem special case submodular optimization since set cover function submodular set cover function attempts find subset objects cover given set concepts example document summarization one would like summary cover important relevant concepts document instance set cover similarly facility location problem special case submodular functions facility location function also naturally models coverage diversity another example submodular optimization problem using determinantal point process model diversity similarly maximum-marginal-relevance procedure also seen instance submodular optimization important models encouraging coverage diversity information submodular moreover submodular functions efficiently combined together resulting function still submodular hence one could combine one submodular function models diversity another one models coverage use human supervision learn right model submodular function problem submodular functions fitting problems summarization also admit efficient algorithms optimization example simple greedy algorithm admits constant factor guarantee moreover greedy algorithm extremely simple implement scale large datasets important summarization problems submodular functions achieved state-of-the-art almost summarization problems example work lin bilmes 2012 shows submodular functions achieve best results date duc-04 duc-05 duc-06 duc-07 systems document summarization similarly work lin bilmes 2011 shows many existing systems automatic summarization instances submodular functions breakthrough result establishing submodular functions right models summarization problems submodular functions also used summarization tasks tschiatschek et al. 2014 show mixtures submodular functions achieve state-of-the-art results image collection summarization similarly bairi et al. 2015 show utility submodular functions summarizing multi-document topic hierarchies submodular functions also successfully used summarizing machine learning datasets specific applications automatic summarization include common way evaluate informativeness automatic summaries compare human-made model summaries evaluation techniques fall intrinsic extrinsic inter-textual intra-textual intrinsic evaluation tests summarization system extrinsic evaluation tests summarization based affects completion task intrinsic evaluations assessed mainly coherence informativeness summaries extrinsic evaluations hand tested impact summarization tasks like relevance assessment reading comprehension etc intra-textual methods assess output specific summarization system inter-textual ones focus contrastive analysis outputs several summarization systems human judgement often wide variance considered good summary means making evaluation process automatic particularly difficult manual evaluation used time labor-intensive requires humans read summaries also source documents issues concerning coherence coverage one metrics used nist annual document understanding conferences research groups submit systems summarization translation tasks rouge metric recall-oriented understudy gisting evaluation essentially calculates n-gram overlaps automatically generated summaries previously-written human summaries high level overlap indicate high level shared concepts two summaries note overlap metrics like unable provide feedback summary coherence anaphor resolution remains another problem yet fully solved similarly image summarization tschiatschek et al. developed visual-rouge score judges performance algorithms image summarization domain independent summarization techniques generally apply sets general features used identify information-rich text segments recent research focus drifted domain-specific summarization techniques utilize available knowledge specific domain text example automatic summarization research medical text generally attempts utilize various sources codified medical knowledge ontologies main drawback evaluation systems existing far need least one reference summary methods one able compare automatic summaries models hard expensive task much effort done order corpus texts corresponding summaries furthermore methods need human-made summaries available comparison also manual annotation performed e.g scu pyramid method case evaluation methods need input set summaries serve gold standards set automatic summaries moreover perform quantitative evaluation regard different similarity metrics
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Computational linguistics
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phpmyadmin phpmyadmin free open source administration tool mysql mariadb portable web application written primarily php become one popular mysql administration tools especially web hosting services tobias ratschiller consultant later founder software company maguma started work php-based web front-end mysql 1998 inspired mysql-webadmin gave project phpadsnew also original author 2000 lack time time phpmyadmin already become one popular php applications mysql administration tools large community users contributors order coordinate growing number patches group three developers olivier müller marc delisle loïc chapeaux registered phpmyadmin project sourceforge took development 2001 july 2015 main website downloads left sourceforge moved content delivery network time releases began pgp-signed afterwards issue tracking moved github mailing lists migrated version 4 uses ajax extensively enhance usability software used html frames features provided program include
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Databases
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mibbit mibbit web-based client web browsers supports internet relay chat irc yahoo messenger twitter developed jimmy moore designed around ajax model user interface written javascript irc application setup default firefox mibbit user interface operates entirely within web browser require installation software user computer modern web browsers support recent versions javascript supported including mozilla firefox internet explorer opera google chrome safari mobile devices apple iphone ipod touch nokia n800 platforms nintendo wii also supported unlike typical web-based irc clients mibbit makes use client–server design model user interface written html javascript using ajax programming techniques client backend written completely java operates independently web server standalone fashion mibbit server design differs web browser component clients chatzilla java applet based irc clients pjirc operate entirely within web browser also differs server-based web proxy irc clients processing takes place remote server client–server design allows centralized mibbit client server mibbit able offer extended functionality present standard irc protocol extensions include channel chat buffer shown mibbit clients join channel another mibbit user already present notification mibbit users typing message distinctive icons allow identification device used mibbit iphone ipod touch wii etc mibbit supports webirc cgiirc protocol allows client send user ip address hostname irc server servers support webirc allow mibbit users appear regular irc clients instead appearing connect mibbit.com domain webirc used unavailable mibbit puts user hostname client realname field encodes user ip address hexadecimal sends ident reply mibbit client ability connect multiple irc servers including servers use ssl/tls join multiple channels configured auto-join often used channels mibbit uses utf-8 character set default also configured use character sets supports nickname tab auto-completion input history tab accessible up/down arrow keys aliases user menu commands saving user preferences mibbit parse smilies links channels nicks mirc color codes automatically create thumbnails image links urls addition mibbit offers integrated pastebin upload service minify urls mibbit also offers typing notification mibbit users recent chat buffer irc channels mibbit users already channel extended whois information user profiles mibbit supports google api allows client support number google services mibbit translate text conversations fly using google translate mibbit also display geographic locations using google maps supports viewing youtube videos addition standard client mibbit also supports widget client embedded web page widget client supports features regular client support multiple server connections mibbit praised cnet lifehacker ease use drupal administrators use add irc widgets sites noting benefits modular design mashable suggests mibbit appropriate resource new irc firefox 3.5 beyond builds already support mibbit default irc protocol handler support encrypted ircs // ssl/tls connections also included mibbit effectively irc proxy potential abused used evade bans blocks resulted client banned accessing irc networks channels mibbit supports dnsbl checking via dronebl service means help block access abusive users botnets mibbit listed open proxy dronebl dns blacklist december 2008 due database glitch mistakenly listed march 2009 prevented mibbit users connecting irc networks make use dronebl service mibbit added dronebl whitelist help prevent future service disruptions june 19 2009 banned permanently freenode new officially supported open-source ajax client introduced
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Web technology
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eidas eidas electronic identification authentication trust services eu regulation set standards electronic identification trust services electronic transactions european single market established eu regulation 910/2014 23 july 2014 electronic identification repeals directive 1999/93/ec 13 december 1999 entered force 17 september 2014 applies 1 july 2016 except certain articles listed article 52 organizations delivering public digital services eu member state must recognize electronic identification eu member states september 29 2018. eidas oversees electronic identification trust services electronic transactions european union internal market regulates electronic signatures electronic transactions involved bodies embedding processes provide safe way users conduct business online like electronic funds transfer transactions public services signatory recipient convenience security instead relying traditional methods mail facsimile appearing person submit paper-based documents may perform transactions across borders like 1-click technology eidas created standards electronic signatures qualified digital certificates electronic seals timestamps proof authentication mechanisms enable electronic transactions legal standing transactions performed paper regulation came effect july 2014 means facilitate secure seamless electronic transactions within european union member states required recognise electronic signatures meet standards eidas eidas result european commission focus europe digital agenda commission oversight eidas implemented spur digital growth within eu intent eidas drive innovation adhering guidelines set technology eidas organisations pushed towards using higher levels information security innovation additionally eidas focuses following regulation provides regulatory environment following important aspects related electronic transactions eidas regulation evolved directive 1999/93/ec set goal eu member states expected achieve regards electronic signing regulation became directly binding law throughout eu july 1 2016 directive made eu member states responsible creating laws would allow meet goal creating electronic signing system within eu directive also allowed member state interpret law impose restrictions thus preventing real interoperability leading toward fragmented scenario contrast directive eidas ensures mutual recognition eid authentication among member states thus achieving goal digital single market eidas provides tiered approach legal value requires electronic signature denied legal effect admissibility court solely advanced qualified electronic signature qualified electronic signatures must given legal effect handwritten signatures electronic seals legal entities version signatures probative value explicitly addressed seals enjoy presumption integrity correctness origin attached data database information linked kind identity number certify person right access personal information involves several steps eidas minimum identity concept name birth date order access sensitive information kind certification needed identity numbers issued two countries refer person
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Computer security
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nokia phone series nokia strategic nomenclature traced back 2005 nseries line launched offering devices flagship specifications premium hardware various price points devices considered bread butter company often positioned showcase latest technologies thanks newfound consumer enterprise interest smartphones time company introduced four additional collections diversify product portfolio meet demands market segments new phone series named eseries targeting small business enterprise customers xseries providing consumer-grade multimedia-focused devices cseries nokia used target low-end mid-range market segments tseries devices exclusive chinese market nokia nseries multimedia smartphone tablet product family served company flagship portfolio aimed users looking pack many features possible one device nokia eseries stands executive consists business-oriented smartphones emphasis enhanced connectivity support corporate e-mail push services phones enterprise market list may also include upcoming devices others previously intended part series scrapped renamed due nokia number-only naming change phones included series nokia xseries stands xpress younger users phones included line feature phones smartphones include features focusing social entertainment music special dedicated keys inbuilt storage facilities succeeded nokia xpressmusic brand phones list may also include upcoming devices others previously intended part series scrapped renamed due nokia number-only naming change phones included series nokia cseries stands core nokia calls core range products offering different phones low-end high-end various markets list may also include upcoming devices others previously intended part series scrapped renamed due nokia number-only naming change phones included series nokia zseries stands zuper supposed nokia meego tablet series originally intended released 2010 early 2011 tablets cancelled unknown reasons product name revealed ovi store november 2010 list may also include upcoming devices others previously intended part series scrapped renamed due nokia number-only naming change tablets included series nokia tseries stands time china-specific line phones made cater services offered china technologies web features disabled replaced country proprietary inventions instance phones offered series would include td-scdma ev-do networks dominant marketplace line launched 13 june 2011 chinese version nokia conversations blog list may also include upcoming devices phones included series nokia aseries stands asha means hope feature-phone line introduced nokia nokia world 2011 phones series developing markets younger users messaging connectivity list may also include upcoming devices phones included series nokia lseries stands lumia means light series smartphones originally made nokia using windows phone operating system officially unveiled nokia world 2011 created exclusive partnership february year allow nokia use modify microsoft mobile operating system devices come host nokia-exclusive services microsoft purchased nokia devices services division april 2014 since lumia series manufactured exclusively microsoft subsidiary microsoft mobile initially retaining nokia branding later dropped favor microsoft first generation phones series include nokia lumia 510 nokia lumia 610 nokia lumia 710 nokia lumia 800 nokia lumia 900 run windows phone 7 subsequent generations use windows phone 8 windows phone 8.1 full list devices found microsoft lumia list lumia devices
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Operating systems
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cloud collaboration cloud collaboration way sharing co-authoring computer files use cloud computing whereby documents uploaded central cloud storage accessed others cloud collaboration technologies allow users upload comment collaborate documents even amend document evolving document businesses last years increasingly switching use cloud collaboration cloud computing marketing term technologies provide software data access storage services require end-user knowledge physical location configuration system delivers services parallel concept drawn electricity grid end-users consume power without needing understand component devices infrastructure required utilize technology collaboration refers ability workers work together simultaneously particular task document collaboration completed face face however collaboration become complex need work people world real time variety different types documents using different devices 2003 report mapped five reasons workers reluctant collaborate result many providers created cloud collaboration tools include integration email alerts collaboration software ability see viewing document time tools team could need put one piece software workers longer rely email cloud file sharing collaboration software collaboration limited primitive less effective methods email ftp among others work particularly well early moves cloud computing made amazon web services 2006 began offering infrastructure services businesses form web services cloud computing began come prominence 2007 google decided move parts email service public cloud long ibm microsoft followed suit lotuslive business productivity online standard suite bpos respectively increase cloud computing services cloud collaboration able evolve since 2007 many firms entered industry offering many features many analysts explain rise cloud collaboration pointing increasing use workers non-authorised websites online tools jobs includes use instant messaging social networks survey taken early 2011 22 workers admitted used one external non-authorised websites cloud collaboration packages provide ability collaborate documents together real time making use non-authorised instant messaging redundant managers properly regulate internet based collaboration system tailor made office also noted cloud collaboration become necessary departments workforces become mobile need access important documents wherever whether internet browser newer technologies smartphones tablet devices tech industry saw several large paradigm changes revolutions brought new economies scale cost-per-transaction cost automating office desktop processes finally cost network bandwidth fell quickly enabled business users apply ict solutions broadly create business value analysts forrester gartner etc believe cloud computing help unleash next wave tech-enabled business innovation mainframe era client/server initially viewed toy technology viable mainframe replacement yet time client/server technology found way enterprise similarly virtualization technology first proposed application compatibility concerns potential vendor lock-in cited barriers adoption yet underlying economics 20 30 percent savings compelled cios overcome concerns adoption quickly accelerated early cloud collaboration tools quite basic limited features newer packages much document-centric approach collaboration sophisticated tools allow users tag specific areas document comments delivered real time viewing document cases collaboration software even integrated microsoft office allow users set video conferences furthermore trend firms employ single software tool solve collaboration needs rather rely multiple different techniques single cloud collaboration providers replacing complicated tangle instant messengers email ftp cloud collaboration today promoted tool collaboration internally different departments within firm also externally means sharing documents end-clients receiving feedback makes cloud computing versatile tool firms many different applications business environment best cloud collaboration tools 2011 report gartner outlines five stage model maturity firms comes uptake cloud collaboration tools firm first stage said reactive email collaboration platform culture resists information sharing firm fifth stage called pervasive universal access rich collaboration toolset strong collaborative culture article argues firms second stage cloud collaboration becomes important analysts expect see majority firms moving model
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Distributed computing architecture
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parse.ly parse.ly technology company provides web analytics content optimization software online publishers parse.ly built three products parse.ly reader parse.ly publisher platform latest parse.ly dash analytics tool large publishers parse.ly content optimization platform online publishers parse.ly product dash built top parse.ly platform dash parses articles publisher site analyzes identify data around metrics specific publishers topics authors sections referrers technology uses natural language processing extracted 350,000 unique topics urls crawled addition providing site analytics dash show users topics resonating people across web webwide trends interface parse.ly founded sachin kamdar andrew montalenti dreamit ventures early stage startup accelerator program philadelphia launched first product parse.ly reader september 2009 may 2009 parse.ly received 20k seed funding dreamit ventures december 2010 parse.ly received 1.8m series funding blumberg capital ff venture capital scott becker cofounder invite media hutchison jonathan axelrod jeffrey greenblatt august 2017 parse.ly received series b funding round 6.8 million round led grotech investors blumberg capital
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Web technology
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p′′ p′′ p double prime primitive computer programming language created corrado böhm 1964 describe family turing machines formula_1 hereinafter written p′′ formally defined set words four-instruction alphabet formula_2 follows böhm gives following program compute predecessor x -1 integer x 0 translates directly equivalent brainfuck program program expects integer represented bijective base-k notation formula_39 encoding digits formula_40 respectively formula_11 digit-string e.g. bijective base-2 number eight would encoded formula_42 8 bijective base-2 112 beginning end computation tape-head formula_11 preceding digit-string
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Programming language topics
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rssowl rssowl news aggregator rss atom news feeds written java built eclipse rich client platform uses swt widget toolkit allow fit look feel different operating systems remaining cross-platform released eclipse public license rssowl free software addition full text searches saved searches notifications filters rssowl v2.1 synchronized discontinued google reader rssowl began small project sourceforge end july 2003 first public version 0.3a rssowl 1.0 released december 19 2001 released support rss atom news feeds initial release also supported exporting feeds pdf rtf html release available windows mac linux solaris rssowl 1.1 added support toolbars quicksearch news feeds version 1.2 improved toolbar customization added support atom 1.0 news feeds versions 1.2.1 1.2.2 added universal binary support mac well drag drop tabs built feed validator rssowl sourceforge project month january 2005 rssowl 2.0 announced march 7 2007 eclipsecon 2007 version 2.0 rebuilt eclipse rich client platform used db4o database storage lucene text searching several milestone versions released final 2.0 version added labeling news feeds pop-up notification new feeds storage news articles news bins final 2.0 version released milestone 9 added support secure password credential storage news filters support embedding firefox 3.0 xulrunner render news feeds proxy support windows rssowl 2.1 released july 15 2011 google reader synchronization support new layouts rssowl longer maintained original developer however maintained fork available known rssowlnix rssowl translated many languages bengali bulgarian czech chinese simplified chinese traditional danish dutch english finnish french galician german greek hungarian italian japanese korean norwegian polish portuguese russian serbian cyrillic serbian latin slovenian spanish swedish thai turkish ukrainian
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Internet protocols
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cachefs cachefs name used several similar software technologies designed speed distributed file system file access networked computers technologies operate storing cached copies files secondary memory typically local hard disk file accessed done locally much higher speeds networks typically allow cachefs software used several unix-like operating systems original unix version developed sun microsystems 1993 another version written linux released 2003 network filesystems dependent network link remote server obtaining file filesystem significantly slower getting file locally reason desirable cache data filesystems local disk thus potentially speeding future accesses data avoiding need go network fetch software check remote file changed since cached much faster reading whole file sprite operating system used large disk block caches located main-memory achieve high performance file system term cachefs found little use describe caches main memory first cachefs implementation 6502 assembler write cache developed mathew r mathews grossmont college used fall 1986 spring 1990 three diskless 64 kb main memory apple iie computers cache files nestar file server onto big board 1 mb dram secondary memory device partitioned cachefs tmpfs computers ran pineapple dos apple dos 3.3 derivative developed course follow wr bornhorst nsf funded instructional computing system pineapple dos features including caching unnamed name cachefs introduced seven years later sun microsystems first unix cachefs implementation developed sun microsystems released solaris 2.3 operating system release 1993 part expanded feature set nfs network file system suite known open network computing plus onc+ subsequently used unix operating systems irix starting 5.3 release 1994 linux operating systems commonly use new version cachefs developed david howells howells appears rewritten cachefs scratch using sun original code linux cachefs currently designed operate andrew file system network file system filesystems similar naming fs-cache cachefs terminology confusing outsiders cachefs backend fs-cache handles actual data storage retrieval fs-cache passes requests netfs cachefs cache facility/layer cache backends like cachefs nfs afs cachefs filesystem fs-cache facility block device used cache simply mounting needs special activation deactivated unmounting daemon using existing filesystem ext3 user_xattr cache cache bound cachefilesd -s project status seems stalled people attempting revive code bring date facility conceptualised following diagram facility known fs-cache designed transparent possible user system applications able use nfs files normal without knowledge cache outdated articles
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Computer file systems
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christoph junghans christoph junghans german computational physicist academic working multiscale modeling computational co-design currently deputy group leader applied computer science group los alamos national laboratory born merseburg educated leipzig university johannes gutenberg university mainz phd 2010 graduate studies also worked forschungszentrum jülich ibm systems technology group junghans joined los alamos national laboratory 2011 postdoc theoretical division became staff member applied computer science group 2014 junghans one authors votca package contributor many open-sources projects including gromacs gentoo linux
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Operating systems
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titan traffic database titan traffic database database allegedly use swedish signals intelligence agency national defence radio establishment fra according news report rapport svt june 2008 based account anonymous source source alleged agency storing massive amounts information talking content leading private citizen lodging complaint police ultimately prosecutor launch full-scale investigation deemed illegal time
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Databases
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altibase hdb altibase hybrid database relational open source database management system manufactured altibase corporation software comes hybrid architecture allows access memory-resident disk-resident tables using single interface supports synchronous asynchronous replication offers real-time acid compliance support also offered variety sql standards programming languages important capabilities include data import export data encryption security multiple data access command sets materialized view temporary tables others altibase so-called hybrid dbms meaning simultaneously supports access memory-resident disk-resident tables via single interface compatible solaris hp-ux aix linux windows supports complete sql standard features multiversion concurrency control mvcc implements fuzzy ping-pong checkpointing periodically backing memory-resident data ships replication database link functionality altibase acquired in-memory database engine electronics telecommunications research institute february 2000 commercialized database october year 2001 altibase changed name in-memory database product spiner altibase 2001 2004 altibase integrated in-memory database disk-resident database create hybrid dbms released version 4.0 renamed altibase hdb altibase released version 5.5.1 6.1.1 2012 version 6.3.1 november 2013 6.5.1 may 2015 altibase claims world first hybrid dbms altibase hdb includes following application development interfaces
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Databases
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sap se sap se systems applications products data processing german multinational software corporation makes enterprise software manage business operations customer relations sap headquartered walldorf baden-württemberg germany regional offices 180 countries company 425,000 customers 180 countries component euro stoxx 50 stock market index xerox exited computer hardware manufacturing industry 1971 asked ibm migrate business systems ibm technology part ibm compensation migration ibm given rights scientific data systems sds /sape software reportedly contract credit 80,000 five ibm engineers ai department dietmar hopp klaus tschira hans-werner hector hasso plattner claus wellenreuther mannheim baden-württemberg working enterprise-wide system based software told would longer necessary rather abandoning project decided leave ibm tech start another company june 1972 founded sap system analysis program development sapd company private partnership german civil code first client german branch imperial chemical industries östringen developed mainframe programs payroll accounting instead storing data punch cards mechanically ibm stored locally electronic system using common logical database activities organization therefore called software real-time system since need process punch cards overnight reason flagship product carried r name late 1990s first version also standalone software could offered interested parties 1973 first commercial product launched sap completes first financial accounting system rf system serves cornerstone ongoing development software modules system eventually bear name sap r/1 offered common system multiple tasks permitted use centralized data storage improving maintenance data technical point view therefore database necessary 1976 sap gmbh systeme anwendungen und produkte der datenverarbeitung systems applications products data processing founded sales support subsidiary five years later private partnership dissolved rights passed sap gmbh headquarters moved following year walldorf germany three years later 1979 sap launched sap r/2 expanding capabilities system areas material management production planning 1981 sap brought re-designed product market however sap r/2 improve period 1985 1990 sap released new sap r/3 1992 sap developed released several versions r/3 1995 mid-1990s sap followed trend mainframe computing client/server architectures development sap internet strategy mysap.com redesigned concept business processes integration via internet result r/3 replaced introduction sap erp central component ecc 5.0 2004 architectural changes also made support enterprise service architecture transition customers services-oriented architecture latest version sap erp 6.0 released 2006 sap erp 6.0 since updated sap enhancement packs recent sap enhancement package 8 sap erp 6.0 2016 august 1988 sap gmbh became sap ag public trading started 4 november 1988 shares listed frankfurt stuttgart stock exchanges 1995 sap included german stock index dax 22 september 2003 sap included stoxx europe 50 company official name became sap ag public limited company 2005 annual general meeting 2014 sap changed ag european company societas europaea se since 2012 sap acquired several companies sell cloud-based products several multibillion-dollar acquisitions seen analysts attempt challenge competitor oracle 2014 sap bought concur technologies provider cloud-based travel expense management software 8.3 billion sap expensive purchase date analysts reactions purchase mixed thomas becker commerzbank questioning whether concur right choice sap credit suisse called acquisition aggressive move 2014 ibm sap began partnership sell cloud-based services likewise 2015 sap also partnered hpe provide secure hybrid cloud-based services running sap platform hpe ibm provide infrastructure services sap sap runs sap hana cloud solution top sap announced additional partnerships microsoft order give customers tools data visualization well improved mobile applications sap exceeded revenue projections due expansion cloud business success sap hana growth also partially attributed acquisitions concur fieldglass company announced plans 2016 invest heavily technology relating internet things iot part strategy capitalize growth market purpose €2 billion planned investment relevant sectors end 2020 sap also launch new product line called sap iot combine large amounts data things connected internet machine learning sap real-time database s/4 hana 2015 company launched sap s/4hana newest generation sap business suite written natively sap hana platform offers cloud on-premises hybrid deployment options customers benefits including smaller data footprint higher throughput faster analytics faster access data also allows existing sap business suite customers upgrade product sap business suite 2016 sap introduced sap hana express edition meant run personal computers cloud computing platforms students small-scale developers january 29 2019 sap announced plans cut approximately 4,000 positions company strategic plan shift modern cloud-based technologies blockchain quantum computing machine learning internet things artificial intelligence fiscal year 2017 sap reported earnings eur€4 billion annual revenue eur€23.5 billion increase 6.3 previous fiscal cycle sap shares traded usd105 per share market capitalization valued usd128 billion december 2018 makes sap valuable company germany sap world third largest software programming company corporation operates europe asia africa middle east north america south america sap focuses 25 industries six industry sectors process industries discrete industries consumer industries service industries financial services public services offers integrated product sets large enterprises mid-sized companies small businesses service-oriented architecture incorporated sap erp enterprise resource planning system products defined within sap enterprise services architecture enterprise soa sap enterprise service oriented architecture enterprise soa sap se service-oriented architecture implementation enterprise soa enabled sap netweaver platform builds benefits web services sap positioned enterprise soa deliver benefits offered service-oriented architecture including enabling flexibility business efficiency sap markets enterprise soa cost-effective way adding new applications existing infrastructure sap solutions currently use enterprise soa mysap crm mysap erp mysap srm sap partners include global services partners cross-industry multinational consulting capabilities global software partners providing integrated products complement sap business suite solutions global technology partners providing user companies wide range products support sap technology including vendors hardware database storage systems networks mobile computing technology extensions partners companies provide functionality complements sap product capabilities products certified sold supported sap partner companies include adobe ca technologies gk software hewlett-packard ids scheer mendix opentext knoa software backoffice associates sap also partnered apple work mobile experience sap enterprise customers part partnership new sap hana cloud platform sdk would delivered exclusively ios result developers build applications based sap hana cloud platform iphone ipad devices partnership announced may 2016 sap products small businesses midsize companies delivered global partner network sap partneredge programme sap partner programme offers set business enablement resources program benefits help partners including value-added resellers vars independent software vendors isvs profitable successful implementing selling marketing developing delivering sap products broad range customers sap community network scn community sap customers partners employees influencers – typically roles developers consultants integrators business analysts – gain share knowledge abap java .net soa technologies plus analytics dashboards business process best practices cloud mobile big data range topics via blogs discussion forums downloads code samples training materials technical library sap uses two-tier structure boards executive board supervisory board 2016 members executive board bill mcdermott ceo chairman joined 2008 robert enslin 2014 bernd leukert 2014 luka mucic cfo 2014 michael kleinemeier 2015 stefan ries 2016 steve singh 2016 gerhard oswald 1996 juergen mueller join executive board 2019 functional units sap split across different organizational units r needs field activities customer support sap labs mainly responsible product development whereas field organizations spread across country responsible field activities sales marketing consulting headquarters responsible overall management well core engineering activities related product development worldwide customer support provided field organizations unified organization called active global support ags sap labs r locations develop improve sap core products sap labs strategically located high-tech clusters around globe four prominent labs sap se located germany india china us labs walldorf founded 1972 became sap primary location beginning focus sap expansion entering highly developed markets 1993 palo alto became part sap labs aiming acquire talented employees sap opened another lab bangalore 2003 among latest sap labs labs czech republic slovakia poland three labs established 2016 labs india largest labs outside germany order manage sap labs sap labs network sln created sln global unit manages regional labs shares best business practices coordinates distributes development projects among individual sap labs locations accelerates product delivery gives sap full access talent drives sap corporate strategy regarding innovation business growth sap user groups independent nonprofit organizations sap customers sap partners serve communications channel members towards sap sap towards markets americas sap users group asug company largest user group 100,000 individuals 3,800 companies asug members professionals work 17 industries many technical business process experts sap ecosystem varied levels experience come small businesses global corporations well universities 2007 sap user group executive network sugen established sap provoked controversy frustration among users 2008 raising cost maintenance contracts issue subject intense discussion among user groups sap cloud platform sap platform-as-a-service paas used deliver in-memory capabilities microservices building extending mobile-enabled cloud applications infrastructure offered global network sap managed data centers sap cloud platform open platform-as-a-service includes in-memory sap hana database management system connects premises cloud-based systems running sap third-party software relies open standards like java javascript node.js cloud foundry integration options sap cloud platform promoted build extend business applications rapid innovation cycles sap apple inc. partnered develop mobile applications ios using cloud-based software development kits sdks sap cloud platform sap founding development partners cloud platform include accenture celonis enterprisealumni walmart sap cloud platform based open source technology developed supported partnership suse company also partnership cloud foundry beta offering sap cloud platform enables customers test give feedback functionalities coming cloud foundry sap launched sap store march 2015 principal e-commerce property allow customers buy products directly web rather traditional sales channels customers purchase free trials starter editions pay credit card paypal launched 2016 sap app center online application marketplace third-party applications integrate extend sap products applications available free well via yearly monthly subscription models applications available range integrations content management software mobile approval management payment platforms july 2018 features 1,500 applications sap two annual conferences sap competitors primarily enterprise resource planning software industry field oracle corporation sap major competitor sap also competes customer relationship management marketing sales software manufacturing warehousing industrial software supply chain management logistics software sectors oracle corporation filed lawsuit sap malpractice unfair competition california courts 2007 sap lost case 2010 ordered pay 1.3 billion cited largest copyright infringement judgment history verdict overturned 2011 lawsuit finally settled 2014 356.7 million resulting pressure saw sap sugen sap user group executive network agree major benchmarking exercise prove value new support pricing policy customers december 2009 sap delayed enterprise support price rises agreement reached benchmarks kpis key performance indicators january 2010 sap reversed direction enterprise support reintroduced standard support package customers move reinstate standard support – 18 percent annual license fees enable customers choose option best meets requirements company said august 2013 sap acquired german software company hybris ecommerce capabilities sap donated several millions dollars variety global health causes including product red campaign global fund addition sap distributed free software south africa part effort towards developing future markets company also encourages employees volunteer social sabbaticals sending teams people different countries aid non-profits sap employees volunteered china india brazil south africa sap arena opened mannheim 2005 home adler mannheim ice hockey team rhein-neckar löwen handball team since 2013 company name sponsor sap center san jose california team also sponsors formula one racing team mclaren nfl teams new york giants new york jets city football group esports squad team liquid sap ambassadors include german tennis player angelique kerber german eventing rider ingrid klimke south african golfers ernie els gary player branden grace sap also engages outreach activities within company 2013 company launched initiative hire employees autism asperger syndrome citing undervalued ability contribute workforce sap aims compose 1 workforce individuals autism year 2020 february 2019 sap accused ‘ improper conduct ’ linked state contracts kenya tanzania anonymous whistle-blower claims firm attorneys sap used twenty third century systems ttcs bribe officials tanzania ports authority tpa win us 6.6-million enterprise resource planning software tender involved provision software licenses services july 2017 allegations made sap involved business transactions controversial politically influential gupta family south africa sap accused paying cad house gupta-controlled company r100 million order secure transnet deal sap denied allegations claiming money paid extension sales force despite cad house prior sap experience guptas dealings sap revealed widely publicized e-mail leak consequence allegations sap launched investigation led four south african managers placed administrative leave along seizure mobile phones computers claas kuehnemann named acting managing director africa investigation continued 26 october 2017 sap announced voluntarily reported u.s. securities exchange commission possible violation us law including foreign corrupt practices act related south african bribery allegations sap investigation conducted law firm baker mckenzie revealed sap paid 7.7 million commissions third-parties linked gupta family securing contracts worth 48 million transnet eskom may 2015 sap agreed pay 3.9 million settle u.s. securities exchange commission civil charges former executive scheme bribe panama government officials order win lucrative technology contracts
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Distributed computing architecture
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nokia eseries nokia eseries consists business-oriented smartphones running symbian os emphasis enhanced connectivity support corporate e-mail push services well enterprise-styled products many featuring qwerty keyboards devices advanced office features s60 platform phones equipped wireless lan also provide voip client sip protocol throughout series lifetime main competitors blackberry products research motion eseries marketed 2011 october 12 2005 mobile phone manufacturer nokia announced company refers eseries consisting three mobile phones nokia e60 nokia e61 nokia e70 may 18 2006 nokia announced addition e50 series refers business device rather smartphone february 12 2007 nokia announced addition three new devices series e61i e65 e90 april 11 2008 nokia australia advised e61i discontinued may 2008 replaced featured smaller e71 later releases included e72 e52 e5 last eseries device nokia e6 2011
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Operating systems
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corpus manager corpus manager corpus browser corpus query system tool multilingual corpus analysis allows effective searching corpora corpus manager usually represents complex tool allows one perform searches language forms sequences may provide information context allow user search positional attributes lemma tag etc called concordances features include ability search collocations frequency statistics well metadata information processed text narrower meaning corpus manager refers server side corpus query engine whereas client side simply called user interface corpus manager software installed personal computer might provided web service
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Databases
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higher-order abstract syntax computer science higher-order abstract syntax abbreviated hoas technique representation abstract syntax trees languages variable binders abstract syntax tree abstract mathematical object certain structure nature instance first-order abstract syntax foas trees commonly used compilers tree structure implies subexpression relation meaning parentheses required disambiguate programs concrete syntax hoas exposes additional structure relationship variables binding sites foas representations variable typically represented identifier relation binding site use indicated using identifier hoas name variable use variable refers directly binding site number reasons technique useful first makes binding structure program explicit need explain operator precedence foas representation need rules binding scope hand interpret hoas representation second programs alpha-equivalent differing names bound variables identical representations hoas make equivalence checking efficient one mathematical object could used implement hoas graph variables associated binding sites via edges another popular way implement hoas example compilers de bruijn indices domain logical frameworks term higher-order abstract syntax usually used refer specific representation uses binders meta-language encode binding structure object language instance logical framework lf λ-construct arrow → type first-order encoding object language construct codice_1 would using twelf syntax codice_2 family object language expressions family codice_3 representation variables implemented perhaps natural numbers shown constant codice_4 witnesses fact variables expressions constant codice_1 expression takes three arguments expression bound variable bound another expression variable bound within canonical hoas representation object language would representation object level variables appear explicitly constant codice_1 takes expression bound meta-level function codice_2 → codice_2 body let function higher-order part expression free variable represented expression holes filled meta-level function applied concrete example would construct object level expression assuming natural constructors numbers addition using hoas signature codice_9 twelf syntax function formula_1 specific representation advantages beyond ones one reusing meta-level notion binding encoding enjoys properties type-preserving substitution without need define/prove way using hoas drastically reduce amount boilerplate code binding encoding higher-order abstract syntax generally applicable object language variables understood variables mathematical sense stand-ins arbitrary members domain often always case instance advantages gained hoas encoding dynamic scope appears dialects lisp dynamically scoped variables act like mathematical variables
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Programming language topics
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sketch engine sketch engine corpus manager text analysis software developed lexical computing limited since 2003 purpose enable people studying language behaviour lexicographers researchers corpus linguistics translators language learners search large text collections according complex linguistically motivated queries sketch engine gained name one key features word sketches one-page automatic corpus-derived summaries word grammatical collocational behaviour currently supports provides corpora 90+ languages sketch engine product lexical computing limited company founded 2003 lexicographer research scientist adam kilgarriff started collaboration pavel rychlý computer scientist working natural language processing centre masaryk university developer manatee bonito two major parts software suite introduced concept word sketches since sketch engine commercial software however core features manatee bonito developed 2003 extended since freely available gpl license within nosketch engine suite sketch engine consists three main components underlying database management system called manatee web interface search front-end called bonito web interface corpus building management called corpus architect manatee database management system specifically devised effective indexing large text corpora based idea inverted indexing keeping index positions given word text used index text corpora comprising tens billions words searching corpora indexed manatee performed formulating queries corpus query language cql manatee written c++ offers api number programming languages including python java perl ruby recently rewritten go faster processing corpus queries bonito web interface manatee providing access corpus search client–server model manatee server bonito plays client part written python corpus architect web interface providing corpus building management features also written python sketch engine used major british publishing houses producing dictionaries macmillan english dictionary dictionnaires le robert oxford university press shogakukan four uk ’ five biggest dictionary publishers use sketch engine
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Databases
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playstation 2 expansion bay playstation 2 expansion bay 3.5 drive bay introduced model 30000 50000 playstation 2 replacing pcmcia slot used models 10000 15000 18000 longer present model 70000 designed network adaptor internal hard disk drive hdd peripherals enhance capabilities ps2 allow online play features shown e3 2001 network adaptor released together launch playstation 2 network play service two models adapter available one dial-up modem ethernet jack broadband internet connection sold north america one ethernet interface sold europe regions start-up disc network access disc included network adaptor installs file memory card connection settings accessible one network adaptor compatible game tony hawk pro skater 3 released november 2001 supported network adaptor hardware software finalized much later network adaptor also provides parallel ata interface molex disk drive power connector allow installation 3.5 ide hard disk drive expansion bay two disk connectors separate circuit boards main network adapter one third party connector replacements including sata connector sata ide converter available slimline playstation 2 models ethernet port built-in official hard disk drive interface however first slimline model scph-70000 complete network adapter onboard including analog modem earliest north american models may modified add external ide connector board scph-75000 series onwards ethernet functionality integrated i/o processor completely internally redesigned completely removing disk interface maximum supported rate 100mbit/s full duplex also backwards compatible 10mbit/s hardware configurations playstation 2 hard disk drive ps2 hdd released july 19 2001 japan together network adaptor march 23 2004 north america requires network adaptor connect playstation 2 receive power hdd 40 gb capacity used games reduce load time putting data hard drive temporarily back memory card data due magicgate copyright protection programs bootable directly hdd e.g playstation broadband navigator playonline viewer pop n music puzzle-dama online keyed system system installs hdd transferred another playstation 2 system files hdd accessed specific programs booted without reinstalled contrary popular belief complete reformat hdd necessary upon transfer hdd consoles else would useful hdd preformatted preinstalled software case north american hdd unit hdd utility disc included allow maintenance hdd including defragmentation disk repair formatting utilities along file manager browser north america final fantasy xi also included 35 north american games support hdd unofficial software called hd loader later also hd advance open playstation loader allow users copy entire games hdd run without discs also allow using standard consumer hard drives ps2 however compatible software expecting standard ps2 hard drive software combined hard drive allows one play games without using original disc desirable protects fragile perhaps rare game discs harm cases may improve performance however practice without controversy hdloader bypasses usual copy protection mechanisms built console allowing piracy linux kit playstation 2 released 2002 included playstation 2 linux software keyboard mouse vga adapter requires rgb monitor sync-on-green network adaptor ethernet 40 gb hard disk drive allows playstation 2 used personal computer mid 2010 possible install use playstation bb navigator ps-bbn hdd-osd hdd utility-disc every playstation 2 console every region achieved use special patched files hdd-osd ps-bbn modified version ulaunch well known piece playstation 2 homebrew software called hacked-ule also possible install homebrew software hdd make launchable hdd-osd ps-bbn game-channel like official hdd game however installing homebrew software hdd still requires much work hex-editor ps-bbn also fully translated given language translation process involves use beta-linux release playstation 2 specially compiled kernel gives access apa-reiserfs partitions 2013 games use hdd install data decrease load time and/or save/load instead using memory card used playstation 2 console region hdd using hex-editor atadpatcher v0.02 type booting software esr well known piece homebrew software ps2 patched copy hdd-osd and/or playstation bb navigator ps-bbn used users see data currently installed way official sony 40 gb hdd scph-20401
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Computer architecture
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ashkan soltani ashkan soltani chief technologist federal trade commission previously independent privacy security researcher based washington dc 2010 2011 worked us federal trade commission staff technologist division privacy identity protection assisted investigations google facebook also worked primary technical consultant wall street journal know series investigating online privacy 2011 testified two different hearings held us senate committees focused privacy related matters julia angwin 2014 book dragnet nation describes soltani 'the leading technical expert ad tracking technology part team washington post shared 2014 pulitzer prize public service guardian us earned 2014 gerald loeb award large newspapers coverage disclosures surveillance done us national security agency soltani first high-profile research project 2009 study supported national science foundation team research ubiquitous secure computing documenting use zombie flash cookies several online advertising networks soltani colleagues berkeley revealed websites recreating tracking cookies consumers deleted storing unique tracking identifiers flash cookies automatically deleted consumers cleared browser cookies publication soltani research class action law firms filed suit several advertising networks websites quantcast clearspring videoegg collectively agreed pay total 3.4 million settle lawsuits 2011 soltani berkeley law professor chris hoofnagle published follow-up study documenting use web browser cache etags store persistent identifiers case flash cookies identifiers stored etags persisted even consumers deleted browser cookies etag tracking issue caught attention several members congress wrote federal trade commission september 2011 urged agency investigate use advanced tracking technologies potentially unfair deceptive business practice several companies performing etag based tracking identified research team subsequently sued class action lawyers january 2013 kissmetrics online advertising network settled etag related lawsuit 500,000
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Computer security
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vera security vera data-centric security platform enables organizations effectively protect kind data policies rules governing access usage data regardless data resides travels vera enables global tracking auditing management data comprehensive security service saas platform vera also provides developers access downloadable software development kit sdk vera launched product april 2015 within first year operations announced partnerships dropbox okta centrify well strategic integrations box vmware microsoft office vera focuses sales marketing efforts large enterprises industries financial services manufacturing media entertainment technology sectors carlos delatorre serves chief executive officer since 2018 joining vera carlos led global sales organization mongodb world ’ fastest-growing database ecosystem first enterprise database company successfully ipo 26 years also served vice president sales clearslide inc. drove enterprise sales strategy business growth prior clearslide carlos served vice president sales dynamicops acquired vmware also held senior sales leadership roles bmc software bladelogic imlogic oblix company headquartered silicon valley secured venture financing notable investors including battery ventures sutter hill ventures capital one growth ventures vera nominated top 10 finalist innovation sandbox competition rsa conference 2016 crn magazine named vera “ 10 coolest security startups 2015 ” since vera additional awards vera privately funded company 31 million venture financing company announced 14 million series round november 2014 included hiring robin daniels cmo february 2016 vera announced 17 million series b round led sutter hill ventures participation existing investors battery ventures amplify partners private investors may 2016 capital one growth ventures joined company series b round financing founding ceo veritas software mark leslie joined vera board directors roger lee battery ventures stefan dyckerhoff sutter hill ventures also serve company board content storage agnostic platform vera capable securing type digital content anywhere ’ stored vera require end-users download proprietary agents plug-ins access secure data offers native integrations common file sharing enterprise platforms like box dropbox okta microsoft office 365 vera incorporates three primary components platform architecture secure cloud platform set end-user clients web-based administration dashboard vera dashboard gives end-users administrators full visibility control activity around content matter stored transmitted vera dashboard admin manage access controls set update policies oversee users activity run audit reports usage vera software development kit march 2016 vera announced sdk allows developers add encryption tracking policy enforcement access control custom legacy business applications vera sdk enables users programmatically execute following tasks device secure files unsecure files give access file specific users groups domains revoke access file specific users groups domains revoke access file users
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Computer security
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native-language identification native-language identification nli task determining author native language l1 based writings second language l2 nli works identifying language-usage patterns common specific l1 groups applying knowledge predict native language previously unseen texts motivated part applications second-language acquisition language teaching forensic linguistics amongst others nli works assumption author l1 dispose towards particular language production patterns l2 influenced native language relates cross-linguistic influence cli key topic field second-language acquisition sla analyzes transfer effects l1 later learned languages using large-scale english data nli methods achieve 80 accuracy predicting native language texts written authors 11 different l1 backgrounds compared baseline 9 choosing randomly identification l1-specific features used study language transfer effects second-language acquisition useful developing pedagogical material teaching methods l1-specific instructions generating learner feedback tailored native language nli methods also applied forensic linguistics method performing authorship profiling order infer attributes author including linguistic background particularly useful situations text e.g anonymous letter key piece evidence investigation clues native language writer help investigators identifying source already attracted interest funding intelligence agencies natural language processing methods used extract identify language usage patterns common speakers l1-group done using language learner data usually learner corpus next machine learning applied train classifiers like support vector machines predicting l1 unseen texts range ensemble based systems also applied task shown improve performance single classifier systems various linguistic feature types applied task include syntactic features constituent parses grammatical dependencies part-of-speech tags surface level lexical features character word lemma n-grams also found quite useful task however seems character n-grams single best feature task building educational applications bea workshop naacl 2013 hosted inaugural nli shared task competition resulted 29 entries teams across globe 24 also published paper describing systems approaches
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Computational linguistics
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javascript osa javascript osa originally javascript osa abbreviated jsosa freeware inter-process communication scripting language macintosh computer javascript osa uses core language mozilla implementation javascript programming language see spidermonkey language used alternative applescript language use unrelated web browser-based scripting seen similar function microsoft jscript .net language windows machines although interoperability two languages system-level scripting language identical mozilla core language extensions added via core object macos object macos object methods obtaining objects bound applications done via appleevent messaging system part macintosh open scripting architecture language first released 2001 bundled late night software flagship product script debugger may 2005 new alpha version language made available testing improved second version language bundled version 4 script debugger javascript osa eventually discontinued due lack interest dropped script debugger 5 2012 os x yosemite introduced javascript automation jxa system-wide support scripting javascript built upon javascriptcore open scripting architecture features objective-c bridge enables entire cocoa applications programmed javascript
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Programming language topics
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flexos flexos discontinued modular real-time multiuser multitasking operating system rtos designed computer-integrated manufacturing laboratory retail financial markets developed digital research flexible automation business unit monterey california since november 1986 marketed since january 1987 reengineered continuation digital research concurrent dos 286 multiuser multitasking operating system flexos designed frank holsworth like portable cp/m concurrent dos 286 concurrent dos 68k concurrent dos v60 flexos written c higher portability across hardware platforms featured low interrupt latency fast context switching supported popular ssl/tls libraries wolfssl original protected mode flexos 286 version 1.3 designed host machines equipped 286 cpus adaptations nec v60 nec v70 motorola 68000 processors planned flexos 286 executables using system native int dch int 220 application program interface filename extension .286 cp/m api front-end fe available well using extension .cmd executables filename extension .68k reserved flexos 68k file extension derived concurrent dos 68k 1986 may 1987 flexos version 1.31 released 80286 machines developer version required ibm pc/at-compatible machine 640 kb conventional 512 kb extended memory either monochrome cga ega graphics adapter flexos supported concept dynamically loadable unloadable subdrivers came driver prototypes floppies hard disks printers serial interfaces ram disks mice console drivers boot flex286.sys kernel would load resource managers device drivers specified config.sys binary file mixed similarly named config.sys configuration file dos shell command.286 would execute config.bat startup batch job instead common autoexec.bat flexos optional dos emulator provided limited pc dos 2.1 compatibility dos .com .exe programs certain restrictions applied since programs executed processor protected mode due bugs earlier steppings intel 80286 flexos 286 dos front-end required least 80286 e2 stepping function properly see loadall problems already caused delays delivery concurrent dos 286 earlier system optionally supported multitasking gem vdi graphical applications flexos 1.31 could linked none either two modules flexos 1.31 also supported flexnet june 1987 also versions 1.0 flexos 386 hosts flexos 186 remote cell controllers flexos 386 provided windowing feature offered pc dos 3.2 gem compatibility flexos 286 flexos 386 versions 2.0 registered 3 july 1989 among major flexos customers 1990/1991 fanuc ibm icl nixdorf siemens tec thorn emi software micrologic novell bought digital research july 1991 x/gem flexos release 1.0 a.k.a x/gem flexos 286 386 flexnet registered 21 december 1992 flexos used primary test platform new novell embedded systems technology nest novell decided abandon development various digital research operating systems multiuser dos successor concurrent dos novell dos successor dr dos sold flexos santa clara california-based integrated systems inc. isi july 1994 deal comprised direct payment half sum well shares representing 2 company company already psos+ another modular real-time multitasking operating system embedded systems continued maintain flexos well flexos version 2.33 current may 1998 flexos 2.34 released soon added support faster cpus 64 mb memory eide atapi cdrom drives integrated systems bought competitor wind river systems february 2000 owned intel since 2009 following list commands supported flexos known flexos versions include motorola 68000 freescale/nxp coldfire mcf5251 platform intel 80286 platform intel 80186/nec v20/v30 platform intel 80386 platform nec v60 platform named ibm 4680 os version 1 ibm originally chose dr concurrent dos 286 basis ibm 4680 computer ibm plant system products point-of-sale terminals 1986 last release ibm 4680 os version 4 replaced ibm 4690 version 1 versions july 1993 ibm announced adoption flexos version 2.32 basis ibm 4690 os version 1 pre-released 24 september 1993 generally made available 25 march 1994 flexos 2.32 supported 286 386 modes efficient memory management better console pipe systems brought overall quality performance improvements compared version came ibm 4680 os version 4 removed limits number applications running concurrently due efficient use kospool order support java ibm 4690 os version 2 brought support long filenames means virtual filesystem vfs architecture introduced fat32 volumes according year store ihl consulting group/ris news ibm 4690 os still market share 12 pos register/client market june 2005 ibm starting phase favour ibm retail environment suse ires ibm continue maintain 4690 os april 2015 recent version released ibm may 2012 ibm 4690 os version 6 release 3 meanwhile toshiba released toshiba 4690 os version 6 release 4 january 2014 siemens used still maintains flexos factory automation equipment well example s5 step-5 operating system s5-dos/mt based flexos 386 x/gem flexnet btrieve whereas smaller s5-dos system also present systems variant digital research personal cp/m-86 siemens industrial systems like coros ls-b/flexos coros os-b/flexos gracis/flexos os-525 flexos x/gem-based computers pc 16-20 pc 32 series available flexos well japanese post office shared terminals iii ctm iv based flexos
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Operating systems
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administrative share administrative shares hidden network shares created windows nt family operating systems allow system administrators remote access every disk volume network-connected system shares may permanently deleted may disabled administrative shares accessed users without administrative privileges administrative shares collection automatically shared resources including following administrative shares following characteristics administrative shares created windows xp home edition administrative shares deleted network share recreated automatically next reboot however possible disable administrative shares disabling administrative shares without caveats previous versions local files feature windows vista windows 7 requires administrative shares operate windows xp implements simple file sharing also known forceguest feature enabled computers part windows domain enabled authenticates incoming access requests network shares guest user account limited access rights windows effectively disables access administrative shares default windows vista later use user account control uac enforce security one uac features denies administrative rights user accesses network shares local computer network unless accessing user registered windows domain using built administrator account windows domain possible allow administrative share access accounts administrative permissions adding localaccounttokenfilterpolicy value registry
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Computer security
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systemtap computing systemtap codice_1 scripting language tool dynamically instrumenting running production linux kernel-based operating systems system administrators use systemtap extract filter summarize data order enable diagnosis complex performance functional problems systemtap consists free open-source software includes contributions red hat ibm intel hitachi oracle community members systemtap debuted 2005 red hat enterprise linux 4 update 2 technology preview four years development systemtap 1.0 released 2009 tracepoints cpython vm jvm added systemtap 1.2 systemtap files written systemtap language saved codice_2 files run codice_1 command-line system carries number analysis passes script allowing run scripts may executed one three backends selected codice_4 option default loadable kernel module fullest capability inspect manipulate part system therefore requires privilege another backend based dynamic program analysis library dyninst instrument user user-space programs requires least privilege newest backend based ebpf byte-code limited linux kernel interpreter capabilities requires intermediate level privilege case module unloaded script finished running scripts generally focus events starting finishing script compiled-in probe points linux tracepoints execution functions statements kernel user-space guru mode scripts may also embedded c may run codice_5 command-line option however use guru mode discouraged systemtap release includes probe points designed remove need guru-mode scripts guru mode required order permit scripts modify state instrumented software apply types emergency security fixes systemtap release 1.7 software implements new stapsys group privilege level following script shows applications setting tcp socket options system options set whether option set successfully many examples shipped systemtap also real-world examples systemtap use war stories page systemtap attach dtrace markers compiled application using macros codice_6 header file
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Operating systems
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proactive proactive parallel suite open-source software enterprise workload orchestration part ow2 community workflow model allows define set executables scripts written scripting language along dependencies proactive parallel suite schedule orchestrate executions optimising use computational resources hood proactive parallel suite relies active object -based java framework optimise task distribution ensure fault-tolerance model created denis caromel professor university nice sophia antipolis several extensions model made later members oasis team inria book theory distributed objects presents asp calculus formalizes proactive features provides formal semantics calculus together properties proactive program execution active objects basic units activity distribution used building concurrent applications using proactive active object runs thread thread executes methods invoked active object active objects passive objects subsystem belongs active object proactive programmer explicitly manipulate thread objects unlike standard java active objects created hosts involved computation active object created activity fact runs thread location local remote perfectly transparent active object manipulated passive instance class active object composed two objects body standard java object body visible outside active object body responsible receiving calls requests active object storing queue pending calls executes calls order specified synchronization policy synchronization policy specified calls managed first first fifo manner thread active object chooses method queue pending requests executes parallelism provided inside active object important decision proactive design enabling use pre-post conditions class invariants side subsystem sends call active object active object represented proxy proxy generates future objects representing future values transforms calls request objects terms metaobject reification performs deep copies passive objects passed parameters proactive library designed developing applications model introduced eiffel// parallel extension eiffel programming language model application structured subsystems one active object therefore one thread subsystem one subsystem active object thread subsystem thus composed one active object number passive objects—possibly passive objects thread one subsystem executes methods objects subsystem shared passive objects subsystems features impact application topology objects make subsystem—the active object passive objects—only active object known objects outside subsystem objects active passive may references onto active objects object o1 reference onto passive object o2 o1 o2 part subsystem also consequences semantics message-passing subsystems object subsystem calls method active object parameters call may references passive objects subsystem would lead shared passive objects passive objects passed parameters calls active objects always passed deep-copy active objects hand always passed reference symmetrically also applies objects returned methods called active objects thanks concepts asynchronous calls futures data sharing application written proactive n't need structural change—actually hardly change all—whether runs sequential multi-threaded distributed environment whenever possible method call active object reified asynchronous request possible call synchronous blocks reply received request asynchronous immediately returns future object future object acts placeholder result not-yet-performed method invocation consequence calling thread go executing code long n't need invoke methods returned object need arises calling thread automatically blocked result method invocation yet available although future object structure similar active object future object active stub proxy code excerpt highlights notion future objects suppose user calls method foo method bar active object foo method returns void bar method returns object class v foo called active object returns immediately current thread execute methods subsystem similarly bar called returns immediately result v ca n't computed yet future object placeholder result method invocation returned point view caller subsystem difference future object object would returned call issued onto passive object methods returned calling thread continues executing code call effectively performed role future mechanism block caller thread gee method called v result yet set inter-object synchronization policy known wait-by-necessity
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Distributed computing architecture
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wave financial services software wave company provides suite financial services online software small businesses wave headquartered leslieville neighbourhood toronto canada company manages 244 billion income expense transactions customers including 16 billion annual invoicing company first product free online accounting software designed businesses 1-9 employees followed invoicing personal finance receipt-scanning software ocr 2012 wave began branching financial services initially payments wave credit card processing payroll wave followed lending wave february 2017 2010 wave launched first free double-entry accounting platform cloud included unlimited bank data downloads company initial product accounting wave double entry accounting tool services include direct bank data imports invoicing expense tracking customizable chart accounts journal transactions accounting wave integrates expense tracking software shoeboxed e-commerce website etsy next product launched payroll wave launched 2012 acquisition smallpayroll.ca payroll wave available u.s.a. canada invoicing wave offshoot company earlier accounting tools additional products launched shortly company rebrand december 2012 include wave also produces free mobile applications integrate online functionality 2017 wave signed agreement provide platform rbc online business banking site rbc-wave service co-branded wave currently supports adding custom taxes via settings however must manually apply tax every transaction come way automate currently supports tax exclusive pricing us sales tax taxes added top prices quoted two effects makes unable handle taxes countries like australia prices must quoted inclusive taxes gst way set invoice total wave calculate tax portion fine b2b businesses makes software unsuitable b2c businesses wave provides software free 3 million customers 200 countries worldwide revenue company comes paid financial services company offers wave previously included advertising pages source revenue advertising removed january 2017 wave software free opposed freemium tools used without tiers limits indefinitely wave currently disclose revenue financial statements publicly however media reports 2016 indicated annual revenues 20 million time 2017 wave raised 24m usd funding led nab ventures ceo kirk simpson cpo james lochrie launched wave accounting inc. july 2009 wave accounting launched public november 16 2010 june 2011 series funding led omers ventures closed september 2011 feddev ontario invested one million dollars funding october 2011 5-million investment led u.s. venture capital firm charles river ventures announced may 2012 wave accounting closed series b financing round led social+capital partnership follow-on participation charles river ventures omers ventures wave acquired company called small payroll november 2011 later launched payroll product called wave payroll february 2012 wave officially launched wave payroll public canada followed american release november year august 2012 company announced acquisition vuru.co online stock-tracking service terms deal disclosed december 2012 company rebranded wave emphasize broadened spectrum services june 11 2019 company announced acquired tax preparation company h r block 537 million
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Distributed computing architecture
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list features removed windows vista windows vista contains many new features number capabilities certain programs part previous windows versions windows xp removed changed – later re-introduced windows 7 following list features present windows xp removed windows vista
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Operating systems
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warp information security warning advice reporting point warp community internal company-based service share advice information computer-based threats vulnerabilities warps typically provide average warps cost much less set computer emergency response centre cert/cc us-cert
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Computer security
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single-source publishing single-source publishing also known single-sourcing publishing content management method allows source content used across different forms media one time labor-intensive expensive work editing need carried one document source document stored one place reused reduces potential error corrections made one time source document benefits single-source publishing primarily relate editor rather user user benefits consistency single-sourcing brings terminology information assumes content manager applied organized conceptualization underlying content poor conceptualization make single-source publishing less useful single-source publishing sometimes used synonymously multi-channel publishing though whether two terms synonymous matter discussion general definition single-source publishing single official delineation single-source publishing multi-channel publishing official governing bodies provide delineation single-source publishing often understood creation one source document authoring tool converting document different file formats human languages multiple times minimal effort multi-channel publishing either seen synonymous single-source publishing similar one source document process results mere reproduction source origins single-source publishing lie indirectly release windows 3.0 1990 eclipsing ms-dos graphical user interfaces help files went unreadable text along bottom screen hypertext systems winhelp on-screen help interfaces allowed software companies cease printing large expensive help manuals products reducing costs producer consumer system raised opportunities well many developers fundamentally changed way thought publishing writers software documentation simply move writers traditional bound books writers electronic publishing rather became authors central documents could reused multiple times across multiple formats first single-source publishing project started 1993 cornelia hofmann schneider electric seligenstadt using software based interleaf automatically create paper documentation multiple languages based single original source file xml developed mid- late-1990s also significant development single-source publishing method xml markup language allows developers separate documentation two layers shell-like layer based presentation core-like layer based actual written content method allows developers write content one time switching multiple different formats delivery methods mid-1990s several firms began creating using single-source content technical documentation boeing helicopter sikorsky aviation pratt whitney canada user manuals ford owners manuals based tagged sgml xml content generated using arbortext epic editor add-on functions developed contractor concept behind usage complex hierarchical content lend discrete componentization could used across variety requirements tagging differences within single document using capabilities built sgml xml ford example able tag single owner manual files 12 model years could generated via resolution script running single completed file pratt whitney likewise able tag 20 subsets jet engine manuals single-source files calling desired version publication time world book encyclopedia also used concept tag articles american british versions english starting early 2000s single-source publishing used increasing frequency field technical translation still regarded efficient method publishing material different languages printed manual translated example online help software program manual accompanies could automatically generated using method metadata could created entire manual individual pages files could translated metadata one step removing need recreate information even database structures although single-source publishing decades old importance increased urgently 2010s consumption information products rises number target audiences expands work developers content creators within industry software documentation perception choice embrace single-source publishing render one operations obsolete editors using single-source publishing criticized below-standard work quality leading critics describe single-source publishing conveyor belt assembly content creation heavily used technical translation risks error regard indexing two words might synonyms english may synonyms another language document produced via single-sourcing index translated automatically two words rendered synonyms synonyms source language target language
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Computer file systems
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tom pattern matching language tom programming language particularly well-suited programming various transformations tree structures xml based documents tom language extension adds new matching primitives c java well support rewrite rules systems rules controlled using strategy language tom good
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Programming language topics
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verax film verax five-minute 2013 short film edward snowden leaking event hong kong produced amateur filmmakers hong kong posted youtube june 2013 name film originates snowden codename means truth teller latin produced group j.shot videos according producers first film ever produced snowden film four parts first depicts central intelligence agency employees discussing snowden case second involves newspaper journalist corresponding snowden third involves hong kong police officers chinese ministry state security employees discussing trying find edward snowden fourth involves characters waiting snowden appear snowden reveals media end film includes extracts snowden interview guardian final captions state snowden departed hong kong 23 june film features mira hong kong hotel snowden stayed rubik cube item according agence france-presse snowden reportedly used identify guardian journalist featured film marcus tsui one project filmmakers described film snapshot time andreas wiseman screen daily wrote plot uses large degree creative licence film created expatriates australia canada ireland united states producers film jeff floro edwin lee shawn tse marcus tsui lee irish citizen sole professional filmmaker involved served editor cinematographer lee served journalist multimedia television sectors worked south china morning post atv home 11 july 2013 two days snowden revealed identity edwin lee contacted friends possibility making film lee tsui created film script one day shooting actors time rehearse lines according producers film intended homage hong kong lee said intrigued snowden came hong kong us love hong kong death call hong kong home filmmakers group youtube page stated nearly every media outlet wanted get hands decided produce short fiction video depict experience hk would affected certain parties namely cia contingent based hk would tasked find snowden hong kong police would stuck u.s. china journalists want get scoop lee said film created catch onto interest snowden attention hong kong according tse 28-year-old native toronto ontario graduate york university film studies programme worked teacher hong kong tried give hong kong limelight think deserves tse said group initially considered outright comedy spoof thriller style jason bourne ultimately opted depiction events may unfolded lee said bourne film series works director michael mann inspired regards snowden presence filmmakers stated snowden central character prominent maelstrom events surrounding knew little snowden give prominent role story lee said film focuses vignettes snowden snowden serves catalyst events affect characters snowden live dialogue film lee said half film focus hong kong half snowden four filmmakers stated political motives shawn tse said knew right get-go film going neutral possible way try infringe upon basically thought snowden trying really idea lee described film snapshot time said snowden popped hong kong got much attention really got people talking wanted give alternative view situation beyond media chase knew cassandra chan served associate producer said us government abused internet response use power internet hopefully good reasons dean napolitano wall street journal wrote film makes subtle observations hong kong sometimes tense relationship mainland china one country two systems policy – underscored scene security official china central government barks orders hong kong police officers aforementioned scene official mainland speaks mandarin hong kong officials speak cantonese according napolitano film implies chinese authorities real power hong kong lee stated scene vehicle represent hong kong relationship china paraphrased alexis lai cnn murkiness beijing role snowden affair regards scene lee said say china n't pulling strings would naïve ... even though gives us autonomy always beijing calls shots officially officials mainland government said influence decisions hong kong authorities 1 july 2013 edwin lee said snowden left hong kong plans write sequel 29 july 2013 filmmakers plans show film film festivals considered making sequel film shot three four days time shooting snowden hiding within hong kong end film production snowden fled russia edwin lee said quickened editing process film could released sooner shorten project agence france-presse stated film stayed true actual locations hong kong snowden reportedly seen scenes shot mira hotel several office interiors used scenes lingerie company let filmmakers use offices edwin lee one filmmakers said filming style lot adrenaline ... guerilla filmmaking style also stated foot-on-the-gas filmmaking lee described filming style docu-drama recreation napolitano said ways resembles modern hong kong crime drama technical dialogue sterile conference rooms time-lapse photography sweeping aerial shots city famous skyline jonathan dehart diplomat stated usage time-lapse-style footage grey clouds hong kong panoramas shaky cam style features spy genre films film used original photography exception two stock photography shots purchased pond5 28 june 2013 filmmakers yet determined total cost film estimate budget 5,000 hong kong dollars 641 us dollars afp said budget shoestring patrick frater variety stated 1 june 2013 total cost 4,200 hkd 550 us adam withnall belfast telegraph said budget 645 u.s. dollars £420 british pounds one-night stay mira expensive single item budget made one third budget filmmakers stated make film gain return investment jeff floro works finance day job said lost money film dean napolitano wall street journal wrote film quite saturday night live -style spoof neither slick thriller given cast non-actors micro budget rebecca keegan los angeles times stated verax feels quite polished insta-film due presence electronic music soundtrack likens soundtrack social network sweeping views hong kong skyscrapers shots within mira hotel keegan added actors leaden delivery sometimes gives neophyte status away voice russia stated shaky camera work usage local actors reminiscent bourne spy thriller series patrick frater variety said film strong production values driving music somewhat amateurish acting performances alexis lai cnn said film surprisingly suspenseful sophisticated gorgeous time-lapse panoramas city shaky cam shots reminiscent hollywood cast film consisted friends four filmmakers dean napolitano wall street journal said cast varying degrees thespian abilities andrew cromeek 25-year-old american chester new york english teacher took role snowden previously acted one commercial one student film filmmakers reviewed friends believed remotely appeared similar snowden shawn tse said looked caucasian white friends see could play snowden cromeek worked company tse worked teacher tse believed cromeek going perfect snowden cromeek believed zero resemblance snowden according tse let cromeek grow beard several days taking hong kong barbershop cromeek gave hairstylist photograph snowden received haircut 50 hong kong dollars us 6.41 according tse hong kong hairstylist warned cromeek careful mistaken snowden cromeek lightened haircolor using gold spray paint put eyeglasses trimmed beard day shooting moles placed neck makeup film team also used special wardrobe make cromeek appear like snowden cromeek reported parents family members friends gave telephone calls film made public cast list film released youtube tuesday 25 june 2013 several publications contacted filming group interviews wall street journal first agence france-presse afp los angeles times afterwards interviews increased interest film 28 june got 5,000 views 30 june gained 8,500 views 2 july got 89,000 views 16 july received 220,000 hits 30 july received almost 250,000 views luke buckmaster online australian political news magazine crikey stated verax nowiki /nowiki greatest asset showcase narrative efficiency getting key points across using language arrangement images solicit logical necessarily emotional responses without needing put fine point jin jiabao china central television said film events vividly portrayed stephanie ip associated press wrote film initially gained popularity 29 july 2013 praise film given way criticism many viewers berating four directors amateur work bad casting adam withnall wrote belfast telegraph many criticised four directors amateur work bad casting independent wider international audience n't forgiving less-than-professional quirks cast television program new day said hope andrew cromeek rest cast better real jobs regards criticism andrew cromeek argued filmmakers expect gain large amount attention youtube filmmakers professional cromeek said think way shot quite cool amateur actors one take kind like shoot go ok done fine completely ok people like 'it worst acting world totally fine ip wrote verax source pride friends made even acknowledge limitations
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Computer security
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opensmtpd opensmtpd also known openbsd smtp server unix daemon implementing simple mail transfer protocol deliver messages local machine relay smtp servers publicly released 17 march 2013 version number 5.3 development since late 2008 opensmtpd primarily developed gilles chehade eric faurot charles longeau part openbsd project design goals include security reliability ease configuration support common use cases source code available isc license portable version like openssh developed child project adds portability code openbsd version releases separately portable version initiated charles longeau adds support multiple operating systems including netbsd freebsd dragonfly bsd several linux distributions development opensmtpd motivated combination issues current smtp daemons difficult configuration complicated difficult audit code unsuitable licensing opensmtpd designed solve problems make mail exchanges accessible wider user-base period development opensmtpd first appeared openbsd 4.6 first release shipped openbsd 5.3 2 october 2015 results security audit released version 5.4.4p1 audited nine issues found result opensmtpd 5.7.2 released address issues opensmtpd attempt openbsd team produce smtp daemon implementation secure reliable high performance simple security audit trivial set administer code designed keep memory cpu disk requirements low possible admitted large mail systems intended run low-end machines trade-offs made higher memory usage would bring indisputable benefits design goals opensmtpd security ease use performance security opensmtpd achieved robust validity check network input path use bounded buffer operations via strlcpy privilege separation mitigate effects possible security bugs exploiting daemon privilege escalation order simplify use smtp opensmtpd implements smaller set functionalities available smtp daemons objective provide enough features satisfy typical usage risk unsuitability esoteric niche requirements
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Operating systems
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joliet file system joliet filesystem commonly used store information cd-rom computer discs defined extension iso 9660 standard joliet specified endorsed microsoft supported versions windows operating system since windows 95 windows nt 4.0 primary focus relaxation filename restrictions inherent full iso 9660 compliance joliet accomplishes supplying additional set filenames encoded ucs-2be utf-16be practice since windows 2000 filenames stored special supplementary volume descriptor safely ignored iso 9660-compliant software thus preserving backward compatibility specification allows filenames 64 unicode characters length however documentation mkisofs states filenames 103 characters length appear cause problems microsoft documented use 110 characters many current pc operating systems able read joliet-formatted media thus allowing exchange files operating systems even non-roman characters involved arabic japanese cyrillic formerly possible plain iso 9660-formatted media operating systems read joliet media include microsoft recommends use joliet extension developers targeting windows allows unicode characters used text fields includes file names volume name secondary volume descriptor type 2 contains information primary one sector 16 offset 40 bytes ucs-2be sector 17 offset 40 bytes result volume name limited 16 characters disktype program prints joliet unicode volume name present
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Computer file systems
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ibrix fusion ibrix fusion parallel file system combined logical volume manager availability features management interface software produced sold supported ibrix incorporated billerica massachusetts hp announced july 17 2009 reached definitive agreement acquire ibrix subsequent acquisition software components ibrix combined proliant servers form x9000 series storage systems x9000 storage systems designed provide network-attached storage standard protocols smb nfs http ndmp well proprietary protocol architecturally file system limited 16 petabytes single namespace based upon design described used hpe storeonce former d2d products
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Computer file systems
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ultra 80 sun microsystems ultra 80 computer workstation shipped november 1999 2002 enclosure fairly large high wide deep heavy tower design launch shipped solaris 2.5.1 available variety different configurations one model 1450 two model 2450 four model 4450 64-bit ultrasparc ii cpus 4 gb ram released ultra 80 sun highest performance workstation ultra 80 similar lower-cost sun ultra 60 somewhat larger supports cpus memory although designed workstation rather server may rack mounted using optional kit enterprise 420r server product based ultra 80 motherboard specialized rack-mountable chassis custom power supplies parts appropriate server applications last order date ultra 80 july 2002 last model stopped shipping october 2002 later ultra 45 introduced 2006 supports maximum two cpus rather four ultra 80 ultra 80 shipped solaris 2.5.1 capable running later versions solaris solaris 10 oracle solaris 11 dropped support ultrasparc ii iii iv processors well linux various unix operating systems ultra 80 run microsoft windows directly although internal pci card sunpci ii pro similar sun could fitted allow use windows full specifications found sun web site although sold either one two four cpus use three cpus supported configuration cpus run 450 mhz 16-kb data 16-kb instruction cache chip secondary 4-mb external cache x1195a part number one cpus cpu integrated floating point processor ultra 80 uses 144-pin 5v 60-ns dimm memory modules either 64 256 mb installed sets four identical dimms 16 dimm sockets possible fit 4 gb 16 256 mb modules memory bus 576 bits wide 512 bits used data 64 bits error correction specifications list maximum throughput 1.78-gb/s performance improved 2-way interleaving used giving 512 mb 2 gb maximum performance achieved 4-way interleaving case 16 memory slots would used providing machine 1 gb 4 gb ram half ultra 80 memory must fitted motherboard half memory riser board care needed handling memory riser board connector designed repeated use must tightened using torque wrench supplied ultra 80 detailed service manual ultra 80 takes one two 1 high sca scsi disk drives internally sold 18.2-gb 36.4-gb disks practice use sca disk internal disks must mounted carrier spud-bracket sun part number 540-3024 scsi ids internal disks 0 3 set sca backplane changed optional 1.44 mb 3.5 ms-dos/ibm compatible floppy drive fitted ultra 80 could purchased new optional 12/24 gb native/compressed dds-3 tape drive work dds-4 drive probably larger tape drives optional 644 mb suncd 32x-speed photo cd compatible cd-rom drive optional 10x dvd-rom could specified well 3rd-party rewritable cd-rom drives could also used.. ultra 80 four full-size slots compliant pci specification version 2.1 systems might inoperable pci 2.2 card installed two upa graphics slots running 112 mhz supporting one two elite3d m3 and/or elite3d m6 graphics options popular creator3d framebuffer supported usually always work ultra 80s sold pgx32 framebuffer even though low performance made appropriate use server rather workstation applications although sold ultra 80s later xvr series framebuffers also work expert3d series sun ultra 80 fitted dual channel ultra-3 scsi controller speed 40 mb/s one controller c0 used internal disk cd-rom dvd-rom tape second channel c1 used external 68-pin ultra wide scsi connector rear ultra 80 sun ultra 80 1 gb/s ethernet used optional sun x1141a ethernet card usb officially supported various usb boards pcs known work linux solaris maximum power consumption documented 380w components list specifies sony 670w 12a power supply sun part number 300-1357 ultra 80 well-built workstation use cheap mass-produced commodity pc parts like sun ultra workstations ultra 5 ultra 10 well cooled suffering none overheating problems sun previous quad-processor machine sparcstation 20 support ultra 80 ended october 2007 addition official support knowledgeable people often sun employees regular visitors comp.unix.solaris comp.sys.sun.hardware comp.sys.sun.admin usenet newsgroups sun ultra 80 workstation facts guide gives following data well known specint 95 specfp 95 benchmarks although search web site standard performance evaluation corporation spec show figures spec ceased use benchmark ultra 80 released last results submitted web site 3rd quarter 1998 little year ultra 80 released november 1999 number results less-commonly-used specfp_rate95 specfp_rate_base95 benchmarks found spec web site given
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Computer architecture
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flags register flags register status register intel x86 microprocessors contains current state processor register 16 bits wide successors eflags rflags registers 32 bits 64 bits wide respectively wider registers retain compatibility smaller predecessors fixed bits bit positions 1 3 5 carry parity adjust zero sign flags inherited even earlier architecture 8080 8085 adjust flag used called auxiliary carry bit 8080 half-carry bit zilog z80 architecture note mask column table bitmask hexadecimal value query flag within flags register value flags registers contain condition codes flag bits let results one machine-language instruction affect another instruction arithmetic logical instructions set flags conditional jump instructions take variable action based value certain flags example codice_1 jump zero codice_2 jump carry codice_3 jump overflow depend specific flags conditional jumps test combinations several flags flags registers moved stack part job saving restoring processor context routine interrupt service routine whose changes registers seen calling code relevant instructions 64-bit mode pushf/popf pushfq/popfq available pushfd/popfd ability push pop flags registers lets program manipulate information flags ways machine-language instructions exist example codice_4 codice_5 instructions clear set direction flag df respectively instruction complement df achieved following assembly code manipulating flags register program determine model installed processor example alignment flag changed 486 program tries modify flag senses modification persist processor earlier 486 starting intel pentium cpuid instruction reports processor model however method remains useful distinguish earlier models
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Computer architecture
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powerpc 600 powerpc 600 family first family powerpc processors built designed somerset facility austin texas jointly funded staffed engineers ibm motorola part aim alliance somerset opened 1992 goal make first powerpc processor keep designing general purpose powerpc processors personal computers first incarnation became powerpc 601 1993 second generation soon followed powerpc 603 powerpc 604 64-bit powerpc 620 powerpc 601 first generation microprocessors support basic 32-bit powerpc instruction set design effort started earnest mid-1991 first prototype chips available october 1992 first 601 processors introduced ibm rs/6000 workstation october 1993 alongside powerful multichip cousin ibm power2 line processors first apple power macintoshes march 14 1994 601 first advanced single-chip implementation power/powerpc architecture designed crash schedule establish powerpc marketplace cement aim alliance order achieve extremely aggressive schedule including substantially new function substantial performance enhancements new instructions importantly power/powerpc first symmetric multiprocessing smp implementation design leveraged number key technologies project management strategies 601 team leveraged much basic structure portions ibm risc single chip rsc processor also included support vast majority new powerpc instructions power instruction set nearly every portion rsc design modified many design blocks substantially modified completely redesigned given completely different unified i/o bus structure smp/memory coherency support new powerpc changes leveraging basic rsc structure beneficial reducing uncertainty chip area/floorplanning timing analysis/tuning worth noting 601 implemented substantial new key functions smp also acted bridge power future powerpc processors assist ibm software developers transitions powerpc start design tape-out first 601 prototype 12 months order push hard establish powerpc market early order help effort rapidly incorporate 88110 bus architecture 601 benefit alliance customers motorola management provided 88110 bus architecture specifications also handful 88110 bus-literate designers help 60x bus logic implementation verification given apple system design team familiar i/o bus structure motorola 88110 i/o bus implementation well defined documented 601 team adopted bus technology improve time market bus renamed 60x bus implemented 601 motorola small number apple designers joined 120 ibm designers creating 601 using 88110 bus basis 60x bus helped schedules number ways helped apple power macintosh team reducing amount redesign support asics reduced amount time required processor designers architects propose document negotiate close new bus interface successfully avoiding bus wars expected 601 management team 88110 bus previous rsc buses n't adopted worthy note accepting 88110 bus benefit apple efforts alliance expense first ibm rs/6000 system design team efforts support asics already implemented around rsc totally different bus structure 60x bus later became fairly long lived basic interface many variants 601 603 604 g3 g4 motorola/freescale powerquicc processors chip designed suit wide variety applications support external l2 cache symmetric multiprocessing four functional units including floating point unit integer unit branch unit sequencer unit processor also included memory management unit integer pipeline four stages long branch pipeline two stages long memory pipeline five stages long floating-point pipeline six stages long first launched ibm systems fall 1993 marketed ibm ppc601 motorola mpc601 operated speeds ranging 50 80 mhz fabricated using 0.6 µm cmos process four levels aluminum interconnect die 121 mm² large contained 2.8 million transistors 601 32 kb unified l1 cache capacity considered large time on-chip cache thanks partly large cache considered high performance processor segment outperforming competing intel pentium powerpc 601 used first power macintosh computers apple variety rs/6000 workstations smp servers ibm groupe bull ibm sole manufacturer 601 601+ microprocessors burlington vermont east fishkill new york production facilities 601 used ibm cmos-4s process 601+ used ibm cmos-5x process extremely small number 601 601+ processors relabeled motorola logos part numbers distributed motorola facts somewhat obscured given various pictures motorola mpc601 particularly one specific case masterful motorola marketing 601 named one time magazine 1994 products year motorola marking updated version powerpc 601v powerpc 601+ operating 90 120 mhz introduced 1994 fabricated newer 0.5 µm cmos process four levels interconnect resulting die measuring 74 mm² 601+ design remapped cmos-4s cmos-5x ibm-only team avoid time-to-market delays design tool changes commonizing fab groundrules 601 601+ designed ibm eda tools ibm systems fabricated ibm-only facilities powerpc 603 first processor implementing complete 32-bit powerpc architecture specified designed low cost low end processor portable embedded use one main features power saving functions doze nap sleep mode could dramatically reduce power requirements drawing 2 mw sleep mode 603 four-stage pipeline five execution units integer unit floating point unit branch prediction unit load/store unit system registry unit separate 8 kb l1 caches instructions data 32/64 bit 60x memory bus reaching 75 mhz 603 core hardware support smp powerpc 603 1.6 million transistors fabricated ibm motorola 0.5 µm cmos process four levels interconnect die 85 mm² large drawing 3 w 80 mhz 603 architecture direct ancestor powerpc 750 architecture marketed apple powerpc g3 603 intended used portable apple macintosh computers could run 68k emulation software performance apple considered adequate due smaller processor caches result apple chose use 603 low-cost desktop performa line caused delay apple powerbook 5300 powerbook duo 2300 apple chose wait processor revision apple use 603 performa 5200 line led processor getting poor reputation aside issue 68k emulation performance performa machines shipped variety design flaws severe related aspects computers design including networking performance stability bus problems width speed contention complexity rom bugs hard disk performance none problems 5200 line aside 68k emulation performance inherently due 603 rather processor retrofitted used 68k motherboards obsolete parts site low end mac rates performa 5200 worst mac all-time 603 found widespread use different embedded appliances performance issues 603 addressed powerpc 603e l1 cache enlarged enhanced 16 kb four-way set-associative data instruction caches clock speed processors doubled reaching 200 mhz shrinking fabrication process 0.35 µm allowed speeds 300 mhz part sometimes called powerpc 603ev 603e 603ev 2.6 million transistors 98 mm² 78 mm² large respectively 603ev draws maximum 6 w 300 mhz powerpc 603e first mainstream desktop processor reach 300 mhz used power macintosh 6500 603e also used accelerator cards phase5 amiga line computers cpus ranging speeds 160 240 mhz powerpc 603e still sold today ibm freescale others like atmel honeywell makes radiation hardened variant rhppc powerpc 603e also heart bebox inc bebox notable since multiprocessing system something 603 n't designed ibm also used powerpc 603e processors thinkpad 800 series laptop computers certain digital oscilloscope series lecroy used powerpc 603e main processor 603e processors also power 66 satellites iridium satellite phone fleet satellites contain seven motorola/freescale powerpc 603e processors running roughly 200 mhz custom 603e processor also used mark 54 lightweight torpedo powerpc 603e core renamed g2 freescale basis many embedded powerquicc ii processors keeps developed freescale powerquicc ii soc processors bear designation mpc82xx come variety configurations reaching 450 mhz freescale enhanced 603e core calling e300 powerquicc ii pro embedded processors larger 32/32 kb l1 caches performance enhancing measures added freescale powerquicc ii pro soc processors bear designation mpc83xx come variety configurations reaching speeds 667 mhz e300 also core mpc5200b soc processor used small efika computer powerpc 604 introduced december 1994 alongside 603 designed high-performance chip workstations entry-level servers support symmetric multiprocessing hardware 604 used extensively apple high-end systems also used macintosh clones ibm low-end rs/6000 servers workstations amiga accelerator boards embedded cpu telecom applications 604 superscalar processor capable issuing four instructions simultaneously 604 six-stage pipeline six execution units work parallel finishing six instructions every cycle two simple one complex integer units one floating point unit one branch processing unit managing out-of-order execution one load/store unit separate 16 kb data instruction l1 caches external interface 32- 64-bit 60x bus operates clock rates 50 mhz powerpc 604 contains 3.6 million transistors fabricated ibm motorola 0.5 µm cmos process four levels interconnect die measured 12.4 mm 15.8 mm 196 mm² drew 14-17 w 133 mhz operated speeds 100 180 mhz powerpc 604e introduced july 1996 added condition register unit separate 32 kb data instruction l1 caches among changes memory subsystem branch prediction unit resulting 25 performance increase compared predecessor 5.1 million transistors manufactured ibm motorola 0.35 µm cmos process five levels interconnect die 148 mm² 96 mm² large manufactured motorola ibm respectively drawing 16-18 w 233 mhz operated speeds 166 233 mhz supported memory bus 66 mhz powerpc 604ev 604r mach 5 introduced august 1997 essentially 604e fabricated ibm motorola newer process reaching higher speeds lower energy consumption die 47 mm² small manufactured 0.25 µm cmos process five levels interconnect drew 6 w 250 mhz operated speeds 250 400 mhz supported memory bus 100 mhz apple dropped 604ev 1998 favor powerpc 750 ibm kept using entry-level models rs/6000 computers several years powerpc 620 first implementation entire 64-bit powerpc architecture second generation powerpc alongside 603 604 geared towards high-end workstation server market powerful paper initially supposed launched alongside brethren delayed 1997 arrive performance comparably poor considerably cheaper 604e surpassed 620 therefore never produced large quantities found little use sole user powerpc 620 groupe bull escala unix machines n't deliver large numbers ibm intended use workstations servers decided wait even powerful rs64 power3 64-bit processors instead 620 produced motorola 0.5 µm process 6.9 million transistors die area 311 mm² operated clock rates 120 150 mhz drew 30 w 133 mhz later model built using 0.35 µm process enabling reach 200 mhz 620 similar 604 five-stage pipeline support symmetric multiprocessing number execution units load/store unit branch unit fpu three integer units larger 32 kb instruction data caches support l2 cache may capacity 128 mb powerful branch load/store units buffers 620 powerful branch history table also larger could dispatch instructions processor handle out-of-order execution efficiently 604 floating point unit also enhanced compared 604 faster fetch cycle support several key instruction hardware like sqrt made combined faster wider data buses efficient fpu 604 system bus wider faster 128-bit memory bus called 6xx bus designed system bus multiprocessor systems processors caches memory i/o connected assisted system control chip supports 32- 64-bit powerpc processors memory addresses larger 32 bits numa environments also used power3 rs64 601 well 604-based rs/6000 systems bridge chip bus later evolved gx bus power4 later gx+ gx++ power5 power6 respectively gx bus also used ibm z10 z196 system z mainframes powerpc 602 stripped version powerpc 603 specially made game consoles motorola ibm introduced february 1995 smaller l1 caches 4 kb instruction 4 kb data single-precision floating-point unit scaled back branch prediction unit offered speeds ranging 50 80 mhz drew 1.2 w 66 mhz consisted 1 million transistors 50 mm² large manufactured 0.5 µm cmos process four levels interconnect 3do developed m2 game console used two powerpc 602 never marketed october 21 1996 fabless semiconductor company quantum effect devices qed announced powerpc 603-compatible processor named powerpc 603q microprocessor forum despite name anything common 603 ground implementation 32-bit powerpc architecture targeted high-end embedded market developed two years small simple energy efficient powerful equaling expensive 603e drawing less power in-order five-stage pipeline single integer unit double precision floating point unit fpu separate 16 kb instruction 8 kb data caches integer unit brand new design fpu derived r4600 save time 69 mm² small using 0.5 µm fabrication process drew 1.2 w 120 mhz 603q designed motorola withdrew contract 603q went full production result 603q canceled qed could continue market processor since lacked powerpc license powerpc 613 seems name motorola given third generation powerpc supposedly renamed powerpc 750 response exponential technology x704 processor designed outgun 604 wide margin hardly sources confirming though might pure speculation reference completely different processor similar powerpc 613 powerpc 614 might name given motorola third generation powerpc later renamed reason 613 suggested part renamed powerpc 7400 motorola even bumped fourth generation powerpc even though architectural differences g3 g4 small hardly sources confirming though might pure speculation reference completely different processor powerpc 615 powerpc processor announced ibm 1994 never reached mass production main feature incorporate x86 core die thus making processor able natively process powerpc x86 instructions operating system running powerpc 615 could either chose execute 32-bit 64-bit powerpc instructions 32-bit x86 instructions mix three mixing instructions would involve context switch cpu small overhead operating systems supported 615 minix special development version os/2 330 mm² large manufactured ibm 0.35 µm process pin compatible intel pentium processors comparable speed processor introduced prototype program killed part fact microsoft never supported processor engineers working powerpc 615 would later find way transmeta worked crusoe processor powerpc 625 early name apache series 64-bit powerpc processors designed ibm based amazon powerpc-as instruction set later renamed rs64 designation powerpc 625 never used final processors powerpc 630 early name high end 64-bit powerpc processor designed ibm unify power powerpc instruction sets later renamed power3 probably distinguish consumer oriented powerpc processors used apple powerpc 641 codename habanero defunct powerpc project ibm 1994–96 timeframe suggested third generation powerpc based 604 processor
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Computer architecture
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tom duff thomas douglas selkirk duff born december 8 1952 computer programmer duff born toronto ontario canada named putative ancestor fifth earl selkirk grew toronto leaside 1974 graduated university waterloo b.math two years later got m.sc university toronto duff worked new york institute technology computer graphics lab mark williams company chicago moving lucasfilm computer research development division thomas porter another lucasfilm employee developed new approach compositing images 1984 paper compositing digital images seminal work algebra image compositing according keith packard porter-duff compositing key technique computer graphics see example xrender glitz duff later worked 12 years bell labs computing science research center worked computer graphics wireless networking plan 9 course work authored well known rc shell version 10 unix operating system duff worked pixar animation studios since 1996
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Operating systems
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r4200 r4200 microprocessor designed mips technologies inc. mti implemented mips iii instruction set architecture isa also known vrx development microprocessor licensed nec company fabricated marketed vr4200 first vr4200 80 mhz part introduced 1993 faster 100 mhz part became available 1994 r4200 developed specifically low-power windows nt computers personal computers laptops mti claimed microprocessor integer performance greater high-end intel i486 80 p5-variant pentium microprocessor r4200 ultimately see use personal computers repositioned embedded microprocessor competed r4600 r4300i variant used widely popular nintendo 64 video game console r4200 scalar design five-stage classic risc pipeline notable feature use integer datapath performing arithmetic operations mantissa portion floating point number separate datapath used exponent scheme reduced cost reducing number transistors size chip power consumption also impacted floating point performance negatively r4200 intended applications require high floating point performance r4200 16 kb instruction cache 8 kb data cache caches direct-mapped instruction cache 32-byte line size whereas data cache 16-byte line size data cache uses write-back write protocol r4200 32-entry translation lookaside buffer tlb data 4-entry tlb instructions 33-bit physical address supported system bus 64 bits wide operates half internal clock frequency r4200 contained 1.3 million transistors area 81 mm nec fabricated r4200 600 nm cmos process three levels interconnect packaged 179-pin ceramic pin grid array compatible r4x00pc r4600 208-pin plastic quad flat pack pqfp used 3.3 v power supply dissipating 1.8 w typically maximum 2 w 80 mhz r4300i derivative r4200 designed mti embedded applications announced 17 april 1995 differs r4200 featuring improved integer multiplier lower latency cut-down 32-bit system bus reduced cost chip area 45 mm fabricated 350 nm process packaged 120-pin pqfp uses 3.3 v power supply dissipates 1.8 w 100 mhz 2.2 w 133 mhz r4300i licensed nec toshiba marketed companies vr4300 tx4300 respectively companies offered 100 133 mhz versions derivative vr4300 developed nec nintendo 64 game console clocked 93.75 mhz labeled nus-cpu although development boards nintendo 64 used stock nec vr4300 cpus final cpu found pin-compatible singular use mips implementation produced significant royalties mti sales nec made mips highest volume mixed 32/64-bit risc isa 1997 nec produced two derivatives r4300 general embedded market vr4305 vr4310 announced 20 january 1998 vr4310 available 100 133 167 mhz manufactured 250 nm process packaged 120-pin pqfp
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Computer architecture
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cascading software cascading software abstraction layer apache hadoop apache flink cascading used create execute complex data processing workflows hadoop cluster using jvm-based language java jruby clojure etc hiding underlying complexity mapreduce jobs open source available apache license commercial support available driven inc. cascading originally authored chris wensel later founded concurrent inc re-branded driven cascading actively developed community number add-on modules available use cascading apache hadoop must also installed hadoop job .jar must contain cascading .jars cascading consists data processing api integration api process planner process scheduler cascading leverages scalability hadoop abstracts standard data processing operations away underlying map reduce tasks developers use cascading create .jar file describes required processes follows ‘ source-pipe-sink ’ paradigm data captured sources follows reusable ‘ pipes ’ perform data analysis processes results stored output files ‘ sinks ’ pipes created independent data process tied data sources sinks called ‘ flow ’ flows grouped ‘ cascade ’ process scheduler ensure given flow execute dependencies satisfied pipes flows reused reordered support different business needs developers write code jvm-based language need learn mapreduce resulting program regression tested integrated external applications like java application cascading often used ad targeting log file analysis bioinformatics machine learning predictive analytics web content mining extract transform load etl applications cascading cited one top five powerful hadoop projects sd times 2011 major open source project relevant bioinformatics included hadoop definitive guide tom white project also cited presentations conference proceedings hadoop user group meetings useful tool working hadoop apache spark
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Distributed computing architecture
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mad mud mad multi access dungeon global mud similar mud1 ran fremp11 bitnet node operated école nationale supérieure des mines de paris mud developed bruno chabrier vincent lextrait two students school began operating 1984 slightly less two years bitnet administrators concerned impact widespread adoption game asked école des mines stop mad installed several nodes world completely banned consequence success resulted complete saturation bitnet several occasions
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Operating systems
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solaris trusted extensions solaris trusted extensions set security extensions incorporated solaris 10 operating system sun microsystems featuring mandatory access control model succeeds trusted solaris family security-evaluated operating systems based earlier versions solaris solaris 10 5/09 common criteria certified evaluation assurance level eal4+ capp rbacpp lspp protection profiles certain trusted solaris features fine-grained privileges part standard solaris 10 release beginning solaris 10 11/06 solaris includes component called solaris trusted extensions gives additional features necessary position successor trusted solaris inclusion features mainstream solaris release marks significant change trusted solaris longer necessary use different solaris release modified kernel labeled security environments solaris trusted extensions opensolaris project trusted extensions additions enhancements include solaris trusted extensions enforce mandatory access control policy aspects operating system including device access file networking print window management services achieved adding sensitivity labels objects thereby establishing explicit relationships objects appropriate explicit authorization allows applications users read and/or write access objects component also provides labeled security features desktop environment apart extending support common desktop environment trusted solaris 8 release delivers first labeled environment based gnome solaris trusted extensions facilitate access data multiple classification levels single desktop environment solaris trusted extensions also delivers labeled device access labeled network communication cipso standard cipso used pass security information within labeled zones solaris trusted extensions complies federal information processing standard fips
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Operating systems
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sctp packet structure stream control transmission protocol sctp simpler basic packet structure tcp consists two basic sections sctp packets require common header section shown blue background sctp packet consists addition common header chunks chunk common format contents vary green bytes diagram signify one chunk chunk length equate multiple 4 bytes protocol implicitly pads chunk trailing zeros additionally chunk type may define set parameters includes inside chunk value field consequently length chunk length two types parameter exist optional/variable-length parameters parameter type parameter length parameter value fields behave like chunk counterparts minimum size parameter 4 bytes occurs parameter value field empty parameter consists type length fields rfc 2960 defines following list chunk types detailed information type provided following subsections following table chunk parameters defined please note following color scheme init ack chunk replicates init chunk except chunk type always 2 defined yet defined yet two re-configuration parameters mentioned may appear chunk combinations valid see rfc 6525 details parameter used sender inform receiver wishes reset sequence numbers message-ids i-data used outgoing streams parameter used sender request receiver resets sequence numbers message-ids i-data used outgoing streams parameter used sender inform receiver wishes reset tsns ssns/mids streams parameter used response re-configuration request except possibly incoming ssn reset request elicits outgoing ssn reset request parameter granted parameter used sender request additional outgoing streams added association i.e incoming streams receiver parameter used sender request additional incoming streams added association i.e outgoing streams receiver pad chunk introduced facilitate path mtu discovery enabling sender arbitrarily increase size sctp packet i-data chunk introduced avoid large message one stream blocking messages streams transmitted sctp primarily uses tsn achieve reliability cases tsn also needed distinguish different data chunks message fragmented data tsn additionally doubles fragment sequence number means fragments message must sent using consecutive tsns effectively blocking data i-data chunk disentangles different uses tsn data chunks data i-data chunks compatible may used association forward-tsn chunk introduced support selective unreliability allows sender tell receiver retransmit number chunks requests receiver consider chunks received i-forward-tsn chunk introduced used instead forward-tsn i-data used instead data
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Internet protocols
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databasespy databasespy multi-database query design database comparison tool altova creator xmlspy databasespy connects many major relational databases facilitating sql querying database structure design database content editing database comparison conversion databasespy database client application windows 7 8 10 windows xp windows server 2003 2008 allows database administrators database developers database-oriented professionals interact multiple relational databases may created different developers databasespy features include quick connection wizard multiple relational databases sql editor auto-completion graphical database design tool database content schema comparison data import export multiple formats databasespy also includes special support xml databases available 32-bit 64-bit versions databasespy connect multiple databases simultaneously including databases different types databasespy automatically adjusts variations sql dialects data type definitions supported relational databases databasespy connects following major database types initial release september 2006 users recognized benefits using single tool consistent user interface multiple databases perform routine tasks querying modifying tables use common graphical interface connect multiple databases possibly across different platforms cited valuable feature databasespy licensed software product uses key protection prevent unlicensed usage databasespy free try no-cost 30-day trial license
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Databases
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fast user switching fast user switching feature i.e term rather loosely specified functionality multi-user operating system allows users switch user accounts single computer without quitting applications logging linux kernel vt subsystem please consult articles pseudoterminal linux console virtual console dates back 1993 understand concept multiple seats meaning 63 vts one vt active given time despite kernel limitation multiseat supported gnu/linux feature fast user switching less severe necessities multi-seat multiple users n't work simultaneously therefore simply works straight forward solution elegant multi-seat kmscon/systemd-consoled combination systemd-logind available desktop environments gnome kde software compilation adapt graphical login session manager e.g gdm sddm lightdm etc underneath solution configured implement fast user switching way installations older environments functionality must enabled appropriate configuration files hot key sequence codice_1 pressed separate login window appear second user log even first user alternatively default install new x sessions started using different display parameters run different virtual terminals e.g codice_2 codice_3 hot key sequences allow user switching take place fast user switching may potentially introduce various security-related complications handled differently among operating systems advantages disadvantages one possibility simple secure first user gets ownership resources second option grant ownership resources new user last one log takes ownership third allow users access shared resources easier intuitive allows example one user record another user conversation windows shared resources sound available sessions red hat linux default behavior give ownership console resources first connected session share resources among groups console users configured manage console ownership differently fast user switching windows based remote desktop services technology windows xp gina component winlogon fast user switching interacts programmatically called automate fast user switch powertoy known super fast user switcher offered 2002 microsoft allowed fast user switching using keyboard hotkey win+q similar alt-tab without even going welcome screen later made unavailable original set powertoys replaced updated versions still works windows xp sp3 32-bit running administrator windows vista gina replaced credential providers however support programmatic initiation fast user switching windows xp fast user switching unavailable computer windows server domain network offline files enabled windows vista later longer restrictions
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Operating systems
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mm tree among linux kernel developers -mm tree refers version kernel source code maintained andrew morton -mm kernel tree used fill role linux kernel development builds formerly identified odd version numbers following 2.6 see section linux kernel version numbering new experimental code used find way 2.6.x-mm kernel build historically -mm tree focused new developments memory management part kernel mm occasionally -mm tree overloaded new patches testing became overly difficult sep 17 2007 andrew morton sent mail saying n't working presence new linux-next git repository offloaded much work made mm maintenance difficult allowing andrew morton continue use quilt manage series mmotm mm moment patches andrew morton includes subset mmotm patches linux-next head called linux-next/akpm also git tree includes patches appear releases mm tree get mm patches given time developers still need quilt ad hoc shell scripts apply full set patches
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Computer architecture
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intrusion detection system intrusion detection system ids device software application monitors network systems malicious activity policy violations malicious activity violation typically reported either administrator collected centrally using security information event management siem system siem system combines outputs multiple sources uses alarm filtering techniques distinguish malicious activity false alarms ids types range scope single computers large networks common classifications network intrusion detection systems nids host-based intrusion detection systems hids system monitors important operating system files example hids system analyzes incoming network traffic example nids also possible classify ids detection approach well-known variants signature-based detection recognizing bad patterns malware anomaly-based detection detecting deviations model good traffic often relies machine learning another reputation-based detection recognizing potential threat according reputation scores ids products ability respond detected intrusions systems response capabilities typically referred intrusion prevention system intrusion detection systems also serve specific purposes augmenting custom tools using honeypot attract characterize malicious traffic although relate network security ids differs firewall firewall looks outwardly intrusions order stop happening firewalls limit access networks prevent intrusion signal attack inside network ids describes suspected intrusion taken place signals alarm ids also watches attacks originate within system traditionally achieved examining network communications identifying heuristics patterns often known signatures common computer attacks taking action alert operators system terminates connections called intrusion prevention system performs access control like application layer firewall ids classified detection takes place network host detection method employed signature anomaly-based network intrusion detection systems nids placed strategic point points within network monitor traffic devices network performs analysis passing traffic entire subnet matches traffic passed subnets library known attacks attack identified abnormal behavior sensed alert sent administrator example nids would installing subnet firewalls located order see someone trying break firewall ideally one would scan inbound outbound traffic however might create bottleneck would impair overall speed network opnet netsim commonly used tools simulating network intrusion detection systems nid systems also capable comparing signatures similar packets link drop harmful detected packets signature matching records nids classify design nids according system interactivity property two types on-line off-line nids often referred inline tap mode respectively on-line nids deals network real time analyses ethernet packets applies rules decide attack off-line nids deals stored data passes processes decide attack nids also combined technologies increase detection prediction rates artificial neural network based ids capable analyzing huge volumes data smart way due self-organizing structure allows ins ids efficiently recognize intrusion patterns neural networks assist ids predicting attacks learning mistakes inn ids help develop early warning system based two layers first layer accepts single values second layer takes first layers output input cycle repeats allows system automatically recognize new unforeseen patterns network system average 99.9 detection classification rate based research results 24 network attacks divided four categories dos probe remote-to-local user-to-root host intrusion detection systems hids run individual hosts devices network hids monitors inbound outbound packets device alert user administrator suspicious activity detected takes snapshot existing system files matches previous snapshot critical system files modified deleted alert sent administrator investigate example hids usage seen mission critical machines expected change configurations signature-based ids refers detection attacks looking specific patterns byte sequences network traffic known malicious instruction sequences used malware terminology originates anti-virus software refers detected patterns signatures although signature-based ids easily detect known attacks difficult detect new attacks pattern available signature-based ids signatures released vendor products on-time updating ids signature key aspect anomaly-based intrusion detection systems primarily introduced detect unknown attacks part due rapid development malware basic approach use machine learning create model trustworthy activity compare new behavior model since models trained according applications hardware configurations machine learning based method better generalized property comparison traditional signature-based ids although approach enables detection previously unknown attacks may suffer false positives previously unknown legitimate activity may also classified malicious existing idss suffer time-consuming detection process degrades performance idss efficient feature selection algorithm makes classification process used detection reliable new types could called anomaly-based intrusion detection systems viewed gartner user entity behavior analytics ueba evolution user behavior analytics category network traffic analysis nta particular nta deals malicious insiders well targeted external attacks compromised user machine account gartner noted organizations opted nta traditional ids systems may attempt stop intrusion attempt neither required expected monitoring system intrusion detection prevention systems idps primarily focused identifying possible incidents logging information reporting attempts addition organizations use idps purposes identifying problems security policies documenting existing threats deterring individuals violating security policies idps become necessary addition security infrastructure nearly every organization idps typically record information related observed events notify security administrators important observed events produce reports many idps also respond detected threat attempting prevent succeeding use several response techniques involve idps stopping attack changing security environment e.g reconfiguring firewall changing attack content intrusion prevention systems ips also known intrusion detection prevention systems idps network security appliances monitor network system activities malicious activity main functions intrusion prevention systems identify malicious activity log information activity report attempt block stop it.. intrusion prevention systems considered extensions intrusion detection systems monitor network traffic and/or system activities malicious activity main differences unlike intrusion detection systems intrusion prevention systems placed in-line able actively prevent block intrusions detected ips take actions sending alarm dropping detected malicious packets resetting connection blocking traffic offending ip address ips also correct errors defragment packet streams mitigate tcp sequencing issues clean unwanted transport network layer options.. intrusion prevention systems classified four different types majority intrusion prevention systems utilize one three detection methods signature-based statistical anomaly-based stateful protocol analysis number techniques attackers using following considered 'simple measures taken evade ids earliest preliminary ids concept delineated 1980 james anderson national security agency consisted set tools intended help administrators review audit trails user access logs file access logs system event logs examples audit trails fred cohen noted 1987 impossible detect intrusion every case resources needed detect intrusions grow amount usage dorothy e. denning assisted peter g. neumann published model ids 1986 formed basis many systems today model used statistics anomaly detection resulted early ids sri international named intrusion detection expert system ides ran sun workstations could consider user network level data ides dual approach rule-based expert system detect known types intrusions plus statistical anomaly detection component based profiles users host systems target systems author ides intelligent system detecting intruders teresa f. lunt proposed adding artificial neural network third component said three components could report resolver sri followed ides 1993 next-generation intrusion detection expert system nides multics intrusion detection alerting system midas expert system using p-best lisp developed 1988 based work denning neumann haystack also developed year using statistics reduce audit trails 1986 national security agency started ids research transfer program rebecca bace bace later published seminal text subject intrusion detection 2000 wisdom sense w statistics-based anomaly detector developed 1989 los alamos national laboratory w created rules based statistical analysis used rules anomaly detection 1990 time-based inductive machine tim anomaly detection using inductive learning sequential user patterns common lisp vax 3500 computer network security monitor nsm performed masking access matrices anomaly detection sun-3/50 workstation information security officer assistant isoa 1990 prototype considered variety strategies including statistics profile checker expert system computerwatch bell labs used statistics rules audit data reduction intrusion detection 1991 researchers university california davis created prototype distributed intrusion detection system dids also expert system network anomaly detection intrusion reporter nadir also 1991 prototype ids developed los alamos national laboratory integrated computing network icn heavily influenced work denning lunt nadir used statistics-based anomaly detector expert system lawrence berkeley national laboratory announced bro 1998 used rule language packet analysis libpcap data network flight recorder nfr 1999 also used libpcap ape developed packet sniffer also using libpcap november 1998 renamed snort one month later snort since become world largest used ids/ips system 300,000 active users monitor local systems remote capture points using tzsp protocol audit data analysis mining adam ids 2001 used tcpdump build profiles rules classifications 2003 yongguang zhang wenke lee argue importance ids networks mobile nodes 2015 viegas colleagues proposed anomaly-based intrusion detection engine aiming system-on-chip soc applications internet things iot instance proposal applies machine learning anomaly detection providing energy-efficiency decision tree naive-bayes k-nearest neighbors classifiers implementation atom cpu hardware-friendly implementation fpga literature first work implement classifier equivalently software hardware measures energy consumption additionally first time measured energy consumption extracting features used make network packet classification implemented software hardware
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Computer security
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mobile secure gateway mobile secure gateway msg industry term software hardware appliance provides secure communication mobile application respective backend resources typically within corporate network addresses challenges field mobile security msg typically composed two components client library gateway client library linked mobile application establishes secure connectivity gateway using cryptographic protocol typically ssl/tls represents secured channel used communication mobile application hosts gateway separates internal infrastructure internet allowing authorized client requests reach specific set hosts inside restricted network client library linked corresponding mobile application provides secure access via gateway set hosts client library exposes public api mobile application mimicking platform default http client library application uses api communicate desired hosts secure way gateway server daemon typically installed onto physical virtual appliance placed dmz gateway public interface exposed internet untrusted network accepts tcp/ip connections mobile applications operates ipv4 and/or ipv6 networks incoming client connections typically use ssl/tls provide security network communication mutual trust communicating peers communication protocol typically based http gateway forwards requests connected apps collection configured hosts typically http https servers services within internal network response host sent back respective mobile app
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Computer security
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separation kernel separation kernel type security kernel used simulate distributed environment concept introduced john rushby 1981 paper rushby proposed separation kernel solution difficulties problems arisen development verification large complex security kernels intended provide multilevel secure operation general-purpose multi-user systems according rushby task separation kernel create environment indistinguishable provided physically distributed system must appear regime separate isolated machine information flow one machine another along known external communication lines one properties must prove separation kernel therefore channels information flow regimes explicitly provided variant separation kernel partitioning kernel gained acceptance commercial aviation community way consolidating onto single processor multiple functions perhaps mixed criticality commercial real-time operating system products genre used aircraft manufacturers safety-critical avionics applications 2007 information assurance directorate u.s. national security agency nsa published separation kernel protection profile skpp security requirements specification separation kernels suitable used hostile threat environments skpp describes common criteria parlance class modern products provide foundational properties rushby conceptual separation kernel defines security functional assurance requirements construction evaluation separation kernels yet providing latitude choices available developers skpp defines separation kernel hardware and/or firmware and/or software mechanisms whose primary function establish isolate separate multiple partitions control information flow subjects exported resources allocated partitions separation kernel core functional requirements include separation kernel allocates exported resources control partitions partitions isolated except explicitly allowed information flows actions subject one partition isolated viz. detected communicated subjects another partition unless flow allowed partitions flows defined configuration data note 'partition 'subject orthogonal abstractions 'partition indicated mathematical genesis provides set-theoretic grouping system entities whereas 'subject allows us reason individual active entities system thus partition collection containing zero elements subject active element may contain zero subjects separation kernel provides hosted software programs high-assurance partitioning information flow control properties tamperproof non-bypassable capabilities provide configurable trusted foundation variety system architectures september 2008 integrity-178b green hills software became first separation kernel certified skpp wind river systems separation kernel technology active certification process 2009 2011 information assurance directorate sunset skpp nsa longer certify specific operating systems including separation kernels skpp noting conformance protection profile offer sufficient confidence national security information appropriately protected context larger system conformant product integrated sel4 microkernel formal proof configured separation kernel proof information flow enforcement together implies high level assurance usecase muen separation kernel also formally verified open source separation kernel x86 machines
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Computer architecture
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james f. allen james frederick allen born 1950 computational linguist recognized contributions temporal logic particular allen interval algebra interested knowledge representation commonsense reasoning natural language understanding believing deep language understanding currently achieved significant hand-engineering semantically-rich formalisms coupled statistical preferences john h. dessaurer professor computer science university rochester allen received ph.d. university toronto 1979 supervision c. raymond perrault joined faculty rochester rochester department chair 1987 1990 directed cognitive science program 1992 1996 co-directed center sciences language 1996 1998 served editor-in-chief computational linguistics 1983-1993 since 2006 also associate director florida institute human machine cognition trips project long-term research build generic technology dialogue spoken 'chat systems includes natural language processing collaborative problem solving dynamic context-sensitive language modeling contrast data driven approaches machine learning requires collect annotate corpora i.e training data firstly plow agent system learns executable task models single collaborative learning session integrates wide ai technologies include deep natural language understanding knowledge representation reasoning dialogue systems planning/agent-based systems machine learning paper outstanding paper award aaai 2007 allen author textbook natural language understanding benjamin-cummings 1987 2nd ed. 1995 also co-author henry kautz richard pelavin josh tenenberg reasoning plans morgan kaufmann 1991 1991 elected fellow association advancement artificial intelligence 1990 founding fellow 1992 became dessaurer professor rochester
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Computational linguistics
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amavis amavis open-source content filter electronic mail implementing mail message transfer decoding processing checking interfacing external content filters provide protection spam viruses malware considered interface mailer mta mail transfer agent one content filters amavis used notable features common mail filtering installation amavis consists postfix mta spamassassin spam classifier clamav anti-virus protection running unix-like operating system many virus scanners 30 spam scanners crm114 dspam bogofilter supported well mtas three topologies interfacing mta supported amavisd process sandwiched two instances mta yielding classical after-queue mail filtering setup amavisd used smtp proxy filter before-queue filtering setup amavisd process consulted provide mail classification forward mail message case consulting client remains charge mail forwarding last approach used milter setup limitations historical client program amavisd-submit since version 2.7.0 before-queue setup preferred allows mail message transfer rejected smtp session sending client after-queue setup filtering takes place mail message already received enqueued mta case mail filter longer reject message deliver possibly tagged discard generate non-delivery notification cause unwanted backscatter case bouncing message fake sender address disadvantage before-queue setup requires resources cpu memory proportional current peak mail transfer rate unlike after-queue setup delay acceptable resource usage corresponds average mail transfer rate introduction option smtpd_proxy_options=speed_adjust postfix 2.7.0 resource requirements before-queue content filter much reduced countries legislation permit mail filtering discard mail message accepted mta rules after-queue filtering setup discarding quarantining messages leaves possibility delivering possibly tagged messages rejecting before-queue setup smtp proxy milter amavis receive mail messages mta one sockets protocol families pf_inet ipv4 pf_inet6 ipv6 pf_local unix domain socket using protocols esmtp lmtp simple private protocol am.pdp used helper program like amavisd-milter interface milters output side protocols esmtp lmtp used pass message back-end mta instance lda message passed spawned process unix pipe esmtp lmtp used session optionally encrypted using tls starttls rfc 3207 extension protocol smtp command pipelining rfc 2920 supported client server code spam scanning enabled daemon process amavisd conceptually similar spamd process spamassassin project cases forked child processes call spamassassin perl modules directly hence performance similar main difference protocols used amavis typically speaks standard esmtp protocol mta spamc/spamd case mta typically spawns spamc program passing message unix pipe spamc process transfers message spamd daemon using private protocol spamd calls spamassassin perl modules design priorities amavisd-new called amavis reliability security adherence standards performance functionality intention mail message could lost due unexpected events like i/o failures resources depletion unexpected program terminations amavisd program meticulously checks completion status every system call i/o operation unexpected events logged possible handled several layers event handling amavis never takes responsibility mail message delivery away mta final success status reported mta message passed back-end mta instance reception confirmed case fatal failures processing transferring message message processed stays queue front-end mta instance re-tried later approach also covers potential unexpected host failures crashes amavisd process one components use program resources like memory size file descriptors disk usage creation subprocesses controlled large mail messages kept memory available memory size impose limit size mail messages processed memory resources wasted unnecessarily great deal attention given security aspects required handling potentially malicious nonstandard garbled data mail messages coming untrusted sources process handling mail messages runs reduced privileges dedicated user id optionally run chroot-ed risks buffer overflows memory allocation bugs largely avoided implementing protocol handling mail processing perl handles dynamic memory management transparently care taken content processed messages inadvertently propagate system perl provides additional security safety net marking tainted data originating wild amavis careful put perl feature good use avoiding automatic untainting data use taint untainting explicitly strategic points late data flow amavis use several external programs enhance functionality de-archivers de-compressors virus scanners spam scanners programs often implemented languages like c c++ potential risk mail message passed one programs cause failure even open security hole risk limited running programs unprivileged user id possibly chroot-ed nevertheless external programs like unmaintained de-archivers avoided use external programs configurable disabled selectively group like decoders virus scanners despite implemented interpreted programming language perl amavis slow good performance functionality implemented amavis speaking external components achieved dealing data large chunks e.g line-by-line avoiding unnecessary data copying optimizing frequently traversed code paths using suitable data structures algorithms well low-level optimizations bottlenecks detected development profiling code benchmarking detailed timing report log help recognize bottlenecks particular installation certain external modules programs like spamassassin command-line virus scanners slow using would constitute vast majority elapsed time processing resources making resources used amavis proportionally quite small components like external mail decoders virus scanners spam scanners selectively disabled needed remains functionality implemented amavis like transferring mail message mta using smtp lmtp protocol checking mail header section validity checking banned mail content types verifying generating dkim signatures consequence mail processing tasks like dkim signing verification mail checking disabled exceptionally fast rival implementations compiled languages even full checks using fast virus scanner spam scanning disabled surprisingly fast implementation protocols message structures closely follows set applicable standards rfc 5322 rfc 5321 rfc 2033 rfc 3207 rfc 2045 rfc 2046 rfc 2047 rfc 3461 rfc 3462 rfc 3463 rfc 3464 rfc 4155 rfc 5965 rfc 6376 rfc 5451 rfc 6008 rfc 4291 several cases functionality re-implemented amavis code even though public cpan perl module exists lacks attention detail following standard lacks sufficient checking handling errors amavis licensed gplv2 license applies current code well historical branches exception supporting programs like monitoring statistics reporting covered new bsd license project started 1997 unix shell script detect block e-mail messages containing virus intended block viruses mta mail transfer agent lda local delivery stage running unix-like platform complementing virus protection mechanisms running end-user personal computers next tool re-implemented perl program later evolved daemonized process dozen developers took turns first five years project developing several variants keeping common goal project name development infrastructure since december 2008 2018-10-09 active branch officially amavisd-new developed maintained mark martinec since march 2002 agreed developers time private correspondence christian bricart lars hecking hilko bengen rainer link mark martinec project name amavis largely interchangeable name amavisd-new branch lots functionality added years like adding protection spam unwanted content besides original virus protection focus kept reliability security adherence standards performance domain amavis.org use project registered 1998 christian bricart one early developers still maintaining domain name registration domain entirely dedicated active branch project mailing list moved sourceforge amavis.org march 2011 hosted ralf hildebrandt patrick ben koetter project web page main distribution site located jožef stefan institute ljubljana slovenia handover 2018 development taking place years 2002 2018 october 9 2018 mark martinec announced general support discussion mailing list retirement project also patrick ben koetter continue new project leader patrick notified migration source code public gitlab repository plan next steps regarding project development history project name project branches varied somewhat initially spelling project name amavis mail virus scanner introduced christian bricart rewrite perl name program amavis-perl daemonized versions initially distributed name amavisd-snapshot amavisd modular rewrite hilko bengen called amavis-ng march 2002 amavisd-new branch introduced mark martinec initially patch amavisd-snapshot-20020300 later evolved self-contained project surviving actively maintained branch nowadays project name preferably spelled amavis name program amavisd name amavis mostly interchangeable amavisd-new hilko bengen
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Computer security
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sambar server jibin server combined http https xmpp ftp smtp pop3 dns dhcp java servlet jsp proxy server developed tod sambar proxy server provided also dial-on-demand service internet service provider limited shareware version widely distributed full functionality available commercial version initially developed microsoft windows platform later version linux also available releases still downloadable free various software distribution sites windows version need server operation system ran even windows 95 windox xp home sambar server came server-side scripting language called cscript derived programming language c. first release appeared 1996/97 latest release 7.0 published march 2007 runs xp win 10 tod sambar claims commercial shareware freeware licensees numbered 200,000 server powered 13,000 commercial internet sites peak end 2007 tod sambar announced end development least october 2015 sambar server still use testified sambar webmaster community forum domain www.sambar.com sambar sever distributed serviced still registered tod sambar name connected internet two mx records registered dns domain name system
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Web technology
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internet relay chat internet relay chat irc application layer protocol facilitates communication form text chat process works client/server networking model irc clients computer programs users install system web based applications running either locally browser 3rd party server clients communicate chat servers transfer messages clients irc mainly designed group communication discussion forums called channels also allows one-on-one communication via private messages well chat data transfer including file sharing client software available every major operating system supports internet access april 2011 top 100 irc networks served half million users time hundreds thousands channels operating total roughly 1,500 servers roughly 3,200 servers worldwide irc usage declining steadily since 2003 losing 60 users 1 million 400,000 2012 half channels half million 2003 irc created jarkko oikarinen august 1988 replace program called mut multiuser talk bbs called oulubox university oulu finland working department information processing science jarkko intended extend bbs software administered allow news usenet style real time discussions similar bbs features first part implemented chat part borrowed parts written friends jyrki kuoppala jukka pihl first irc network running single server named tolsun.oulu.fi oikarinen found inspiration chat system known bitnet relay operated bitnet jyrki kuoppala pushed jarkko ask oulu university free irc code also could run outside oulu finally got released jyrki kuoppala immediately installed another server first irc network jarkko got friends helsinki university tampere university start running irc servers number users increased universities soon followed time jarkko realized rest bbs features probably would n't fit program jarkko got touch people university denver oregon state university irc network running wanted connect finnish network obtained program one jarkko friends vijay subramaniam—the first non-finnish person use irc irc grew larger got used entire finnish national network—funet—and connected nordunet scandinavian branch internet november 1988 irc spread across internet middle 1989 40 servers worldwide august 1990 first major disagreement took place irc world a-net anarchy net included server named eris.berkeley.edu open required passwords limit number connects greg wumpus lindahl explains wildcard server line people hooking servers nick-colliding everyone eris free network efnet made eris machine first q-lined q quarantine irc wumpus words eris refused remove line formed efnet n't much fight got hubs join almost everyone else got carried along a-net formed eris servers efnet formed non-eris servers history showed servers users went efnet anet disbanded name efnet became meaningless one irc network around time irc used report 1991 soviet coup d'état attempt throughout media blackout previously used similar fashion gulf war chat logs events kept ibiblio archive another fork effort first really made big lasting difference initiated 'wildthang u.s. october 1992 forked efnet ircd version 2.8.10 meant test network develop bots quickly grew network friends friends europe canada separate new network worked december french servers connected canadian ones end month french canadian network connected us one forming network later came called undernet undernetters wanted take ircd attempt make less bandwidth consumptive try sort channel chaos netsplits takeovers efnet started suffer latter purpose undernet implemented timestamps new routing offered cservice—a program allowed users register channels attempted protect troublemakers first server list presented february 15 1993 includes servers usa canada france croatia japan august 15 new user count record set 57 users may 1993 rfc 1459 published details simple protocol client/server operation channels one-to-one one-to-many conversations notable significant number extensions like ctcp colors formats included protocol specifications character encoding led various implementations servers clients diverge fact software implementation varied significantly one network network implementing policies standards code bases summer 1994 undernet forked new network called dalnet named founder dalvenjah formed better user service user channel protections one significant changes dalnet use longer nicknames original ircd limit 9 letters dalnet ircd modifications made alexei lefler kosut dalnet thus based undernet ircd server although dalnet pioneers efnet abandoners according james ng initial dalnet people ops startrek sick constant splits/lags/takeovers/etc dalnet quickly offered global wallops ircop messages seen users +w /mode nickname +w longer nicknames q lined nicknames nicknames used i.e chanserv ircop nickserv etc global k lines ban one person entire domain server entire network ircop communications globops +h mode showing ircop helpop etc much dalnet new functions written early 1995 brian morpher smith allow users nicknames control channels send memos july 1996 months flame wars discussions mailing list yet another split due disagreement development ircd evolve notably european servers europe side later named ircnet argued nick channel delays efnet side argued timestamps also disagreements policies european side started establish set rules directing ircops could could point view opposed us side ircnet servers europe efnet servers us event also known great split many irc societies efnet since august 1998 grown passed number users northern autumn year 2000 efnet 50,000 users ircnet 70,000 golden era 1990s early 2000s 240,000 users quakenet 2004 irc seen significant decline losing around 60 users 2003 2012 users moving modern social media platforms like facebook twitter also open platforms like xmpp developed 1999 certain networks like freenode followed overall trend quadrupled size period 2016 freenode largest irc network around 90,000 users 2016 new standardization effort way working group called ircv3 focuses advanced client features like instant notifications better history support improved security.. 2019 major irc networks fully adopted proposed standard irc open protocol uses tcp optionally tls irc server connect irc servers expand irc network users access irc networks connecting client server many client implementations mirc hexchat irssi server implementations e.g original ircd irc servers require users register account nick nickname required connected irc originally plain text protocol although later extended request assigned port 194/tcp iana however de facto standard always run irc 6667/tcp nearby port numbers example tcp ports 6660–6669 7000 avoid run ircd software root privileges protocol specified characters 8-bit specify character encoding text supposed use cause problems users using different clients and/or different platforms want converse client-to-server irc protocols use today descended protocol implemented irc2.4.0 version irc2 server documented rfc 1459 since rfc 1459 published new features irc2.10 implementation led publication several revised protocol documents rfc 2810 rfc 2811 rfc 2812 rfc 2813 however protocol changes widely adopted among implementations although many specifications irc protocol published official specification protocol remains dynamic virtually clients servers rely strictly rfcs reference microsoft made extension irc 1998 via proprietary ircx later stopped distributing software supporting ircx instead developing proprietary msnp standard structure network irc servers tree messages routed along necessary branches tree network state sent every server generally high degree implicit trust servers architecture number problems misbehaving malicious server cause major damage network changes structure whether intentional result conditions underlying network require net-split net-join results lot network traffic spurious quit/join messages users temporary loss communication users splitting servers adding server large network means large background bandwidth load network large memory load server established however message multiple recipients delivered fashion similar multicast meaning message travels network link exactly strength comparison non-multicasting protocols simple mail transfer protocol smtp extensible messaging presence protocol xmpp irc daemon also used local area network lan irc thus used facilitate communication people within local area network internal communication irc line-based structure clients send single-line messages server receive replies messages receive copies messages sent clients clients users enter commands prefixing '/ depending command may either handled entirely client generally commands client recognize passed directly server possibly modification due nature protocol automated systems always correctly pair sent command reply full reliability subject guessing basic means communicating group users established irc session channel channels network displayed using irc command list lists currently available channels modes +s +p set particular network users join channel using join command clients available /join channelname messages sent joined channels relayed users channels available across entire irc network prefixed local server use less common channel types include '+ channels—'modeless channels without operators — channels form timestamped channel normally non-timestamped networks users channels may modes represented single case-sensitive letters set using mode command user modes channel modes separate use letter mean different things e.g user mode invisible mode channel mode invite modes usually set unset using mode command takes target user channel set modes set unset parameters modes need channel modes take parameters channel modes apply user channel add remove mask e.g ban mask list associated channel rather applying channel whole modes apply users channel associated symbol used represent mode names replies sent clients first joining channel use names command many clients also used represent client displayed list users channel display indicator user modes order correctly parse incoming mode messages track channel state client must know mode type modes apply user channel symbol goes letter early implementations irc hard-coded client de facto standard extension protocol called isupport sends information client connect time using numeric 005 small design fault irc regarding modes apply users channels names message used establish initial channel state send one mode per user channel multiple modes set single user example user holds operator status +o voice status +v channel new client unable see mode less priority i.e voice workarounds possible client server side none widely implemented many daemons networks added extra modes modified behavior modes list channel operator client irc channel manages channel irc channel operators easily seen symbol icon next name varies client implementation commonly symbol prefix green circle latin letter +o networks operator also users maintain elevated rights local server entire network called irc operators sometimes shortened ircops opers confused channel operators implementation ircd varies privileges irc operator given ircd rfc 1459 claims irc operators necessary evil keep clean state network need able disconnect reconnect servers additionally prevent malicious users even harmful automated programs entering irc irc operators usually allowed disconnect clients completely ban ip addresses complete subnets networks carry services nickserv et al usually allow irc operators also handle basic ownership matters privileged rights may include overriding channel bans able join channels would allowed join opered able op channels would able without opered auto-opped channels always forth hostmask unique identifier irc client connected irc server irc servers services clients including bots use identify specific irc session format hostmask codice_1 hostmask looks similar confused e-mail address nick part nickname chosen user may changed connected user part username reported ident client ident available client username specified client connected used prefixed tilde host part hostname client connecting ip address client resolved valid hostname server used instead hostname privacy implications exposing ip address hostname client irc daemons also provide privacy features inspircd unrealircd +x mode hashes client ip address masks part client hostname making unreadable users ircops users may also option requesting virtual host vhost displayed hostmask allow anonymity irc networks freenode use cloaks indicate user affiliated group project issues original design irc amount shared state data limitation scalability absence unique user identifications leading nickname collision problem lack protection netsplits means cyclic routing trade-off scalability sake real-time user presence information protocol weaknesses providing platform abuse transparent optimizable message passing encryption issues addressed modern irc irc connections usually unencrypted typically span long time periods attractive target dos/ddos attackers hackers careful security policy necessary ensure irc network susceptible attack takeover war irc networks may also k-line g-line users servers harming effect irc servers support ssl/tls connections security purposes helps stop use packet sniffer programs obtain passwords irc users little use beyond scope due public nature irc channels ssl connections require client server support may require user install ssl binaries irc client specific patches modules computers networks also use ssl server server connections provide special channel flag codice_2 allow ssl-connected users channel disallowing operator identification clear text better utilize advantages ssl provides irc served early laboratory many kinds internet attacks using fake icmp unreachable messages break tcp-based irc connections nuking annoy users facilitate takeovers one contentious technical issues surrounding irc implementations survives day merit nick/channel delay vs. timestamp protocols methods exist solve problem denial-of-service attacks take different approaches problem original irc protocol implemented two servers split rejoined two sides network would simply merge channels user could join split server channel existed side network empty gain operator status would become channel operator combined channel netsplit ended user took nickname existed side network server would kill users rejoining i.e. 'nick-collision often abused mass-kill users channel thus creating opless channels operators present deal abuse apart causing problems within irc encouraged people conduct denial service attacks irc servers order cause netsplits would abuse nick/channel delay abbreviated nd/cd solution problem simple user signs nickname becomes available channel ceases exist users parted often happens netsplit server allow user use nickname join channel certain period time delay passed idea behind even netsplit occurs useless abuser take nickname gain operator status channel thus collision nickname 'merging channel occur extent inconveniences legitimate users might forced briefly use different name rejoining appending underscore popular alternative timestamp ts protocol takes different approach every nickname channel network assigned timestampthe date time created netsplit occurs two users side free use nickname channel two sides joined one survive case nicknames newer user according ts killed channel collides members users channel merged channel operators losing side split lose channel operator status ts much complicated protocol nd/cd design implementation despite gone several revisions implementations still problems desyncs two servers network disagree current state network allowing much leniency allowed 'losing side original ts protocols example protection users setting bans modes losing channel would merged split rejoined even though users set modes lost channel operator status modern ts-based irc servers also incorporated form nd and/or cd addition timestamping attempt curb abuse networks today use timestamping approach timestamp versus nd/cd disagreements caused several servers split away efnet form newer ircnet split efnet moved ts protocol ircnet used nd/cd recent versions ircnet ircd well ircds using ts6 protocol including charybdis nd extended/replaced mechanism called save mechanism assigns every client uid upon connecting irc server id starts number forbidden nicks although ircds namely ircnet inspircd allow clients switch uid nickname two clients nickname join different sides netsplit nick collision first server see collision force clients change nick uid thus saving clients disconnected ircnet nickname also locked time nd prevent clients changing back original nickname thus colliding thousands running irc networks world run various implementations irc servers administered various groups irc operators protocol exposed irc users similar irc networks accessed client software although might slight incompatibilities limited functionality due differing server software implementations largest irc networks traditionally grouped big four designation networks top statistics big four networks change periodically due community nature irc large number networks users choose historically big four irc reached 6 million simultaneous users 2001 10 million users 2003 dropping 371k 2018 october 2018 largest irc networks today top 100 irc networks around 370k users connected peak hours three recognized uniform resource identifier uri schemes internet relay chat codice_3 codice_4 codice_5 supported allow hyperlinks various forms including items enclosed within brackets optional used necessary connect specified host network known irc client join specified channel used within client another application web browser irc default uri irc6 specifies connection made using ipv6 ircs specifies secure connection per specification usual hash symbol prepended channel names begin alphanumeric character—allowing omitted implementations example mirc unconditionally resulting usually unintended extra example channel included url implementations allow multiple channels specified separated commas client software exists various operating systems software packages well web-based inside games many different clients available various operating systems including windows unix linux mac os x mobile operating systems ios android windows mirc one popular clients programs extensible plug-ins also serve platforms irc clients instance client called erc written entirely emacs lisp included v.22.3 emacs therefore platform run emacs run erc number web browsers built-in irc clients opera version 12.18 earlier chatzilla add-on mozilla firefox included built-in component seamonkey web-based clients mibbit open source kiwiirc run browsers games war§ow unreal tournament unreal tournament 2004 uplink spring engine -based games 0 a.d. zdaemon included irc ustream chat interface irc custom authentication well twitch.tv formerly justin.tv typical use bots irc provide irc services specific functionality within channel host chat-based game provide notifications external events however irc bots used launch malicious attacks denial service spamming exploitation program runs daemon server functions persistent proxy known bnc bouncer purpose maintain connection irc server acting relay server client simply act proxy client lose network connectivity bnc may stay connected archive traffic later delivery allowing user resume irc session without disrupting connection server furthermore way obtaining bouncer-like effect irc client typically text-based example irssi may run always-on server user connects via ssh also allows devices ssh functionality actual irc client installed connect irc allows sharing irc sessions keep irc client quitting ssh connection closes client run inside terminal multiplexer gnu screen tmux thus staying connected irc network constantly able log conversation channels user interested maintain channel presence network modelled setup 2004 irc client following client-server model called smuxi launched numerous search engines available aid user finding looking irc generally search engine consists two parts back-end spider/crawler front-end search engine back-end spider/webcrawler work horse search engine responsible crawling irc servers index information sent across information indexed usually consists solely channel text text publicly displayed public channels storage method usually sort relational database like mysql oracle front-end search engine user interface database supplies users way search database indexed information retrieve data looking front-end search engines also coded numerous programming languages search engines spider single application responsible crawling irc indexing data however others user based indexers latter rely users install add-on irc client add-on sends database channel information whatever channels user happens many users implemented ad hoc search engines using logging features built many irc clients search engines usually implemented bots dedicated particular channel group associated channels irc changed much life internet new server software added multitude new features effort standardization adding new features irc protocol ircv3 working group irc still lacks single globally accepted standard convention transmit characters outside 7-bit ascii repertoire irc servers normally transfer messages client another client byte sequences without interpretation recoding characters irc protocol unlike e.g mime http lacks mechanisms announcing negotiating character encoding options put responsibility choosing appropriate character codec client practice irc channels largely used character encodings also used operating systems particular unix derivatives respective language communities today utf-8 encoding unicode/iso 10646 would likely contender single future standard character encoding irc communication standard ever relaxed 510-byte message size restriction utf-8 ascii compatible covers superset commonly used coded character set standards much like conventional p2p file sharing users create file servers allow share files using customised irc bots scripts irc client often users group together distribute warez via network irc bots technically irc provides file transfer mechanisms file sharing implemented irc clients typically using direct client-to-client dcc protocol file transfers negotiated exchange private messages clients vast majority irc clients feature support dcc file transfers hence view file sharing integral feature irc commonplace usage protocol however sometimes also causes dcc spam dcc commands also used exploit vulnerable clients performing action disconnecting server exiting client
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Internet protocols
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datagravity datagravity inc. industry data management company produced security software company founded april 2012 paula long john joseph company raised 92m charles river ventures general catalyst andreessen horowitz accel partners datagravity announced first products vmworld 2014 best show new technology awards event began shipping first products october 2014 company focused protection security data stored array named new type storage data-aware storage publicly changed product strategy february 2016 data storage appliances software solution focused behavioral data security product strategy change resulted multiple rounds layoffs multiple reports use conflicting terminology final fate company reports say hytrust acquired datagravity reports including press release issued hytrust say hytrust acquired assets datagravity signed liquidator hytrust told fortune founder ceo paula long left datagravity weeks transaction announced co-founder john joseph left time according reports datagravity ceased day-to-day operations june 2017 cancelled employee benefit plans signed company liquidator barry kallander kallander group one report correspondence datagravity president barry kallander states corporation sold assets company ... unfortunately common shares worthless conversely datagravity cto david siles quoted saying company shut transaction n't fire sale acquired complete vision add value customers love together offer compelling offering marketplace solving pressing needs many enterprises approximately 20 former datagravity employees joined hytrust support datagravity product integration led former datagravity cto david siles datagravity products remain part hytrust portfolio cloudadvisor suite
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Computer security
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