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general comprehensive operating system general comprehensive operating system gcos originally gecos general electric comprehensive operating supervisor family operating systems oriented toward 36-bit ge/honeywell mainframe computers original version gcos developed general electric 1962 operating system still used today recent versions gcos 7 gcos 8 servers mainframes produced groupe bull primarily emulation provide continuity legacy mainframe environments note gcos 7 gcos 8 separate branches operating system continue developed alongside gecos-ii operating system developed general electric 36-bit ge-635 1962-1964 bore close resemblance architecturally ibsys ibm 7094 less dos/360 system/360 however ge-635 architecture different ibm system/360 gecos ambitious dos/360 gecos-ii supported time-sharing tss batch processing dynamic allocation memory ibm fixed partitions time making true second-generation operating system honeywell acquired ge computer division gecos-iii renamed gcos 3 heart 24-bits ge-400 series hardware line renamed h-6000 adding eis enhanced instruction set character oriented instead word oriented later honeywell marketing created series 60 renamed h-6000 level 66 later dps 8 honeywell along european affiliate cii-honeywell bull launched new 32-bit product line called level 64 later became dps 7 name gcos extended operating systems honeywell-marketed product lines gcos-64 completely different 32-bit operating system level 64 series similar parallel development called multics designed honeywell honeywell bull developers france boston gcos-62 operating system another 32-bit low-end line machines level 62 series designed italy gcos-61 operating system new version small system made france model 58 later level 61/58 operating system new 16-bit minicomputer line massachusetts billerica level 6 got name gcos 6 another renaming hardware product lines occurred 1979 level 6 becoming dps 6 level 62 becoming dps 4 level 64 becoming dps 7 level 66 becoming dps 8 operating systems retained gcos brand-name gcos 6 gcos 4 gcos 7 gcos 8 introduced gcos 8 extensive rewrite gcos 3 changes made support true virtual memory management demand paging changes also required new hardware gcos 3 supported maintenance several years announcement renaming gcos 3 later gcos 7 gcos 8 featured good codasyl relational database called integrated data store ids model successful idms several transaction processing monitors designed gcos 3 gcos 8 early attempt tp gcos 3 transaction processing executive assumed unix new process started handle transaction enjoyed limited success another tp system transaction driven system tds soon developed gcos 3 using single process potentially multiple threads service transactions tds essentially honeywell development later replaced backward-compatible transaction processing 8 tp8 gcos 8 profited overhaul gcos system architecture came gcos 8 make full use virtual memory concepts tp8 used multiple static processes way similar unix daemons handle incoming transactions multiplexed way tds tp8 successor commercially successful tds predated ibm cics similar architecture similar product also called tds developed gcos-7 internal architecture completely different dps 6 dps 4 ex-level 62 superseded motorola 68000- later powerpc minicomputers running unix product lines discontinued though gcos 6 ran emulator top aix dps 7 line along gcos 7 continued evolve dps 7000 hardware base late 1980s honeywell sold computer business joint venture initially included nec bull honeywell still holding stake time couple years bull took company nec supplied several generations mainframe hardware high end would run gcos 8 acos-4 operating system bull used nomenclature dps-9000 entire gcos 8-based mainframe line included models designed bull nec late 1990s early 2000s bull desire center development single hardware base running commodity intel chips bull value-adds platform called novascale based itanium 2 processors runs windows linux natively however instruction set simulators dps 7000 dps 9000 allowed gcos 7 gcos 8 run platform gcos 7 also ported lower-end xeon-based platform bull publicly stated gcos 8 continue developed itanium systems bull continues invest development money support gcos 7 gcos 8 still customers countries around world support gcos 7 gcos 8 bull planned least 2025 including regular hardware software upgrades trace gcos influence remains today modern unix systems early unix systems bell labs used gcos machines print spooling various services field added /etc/passwd carry gcos id information called gecos field survives today pw_gecos member used user full name human-id information due historically important far-reaching influence gcos sometimes known king operating systems gcos multithreading multiprogramming operating system originally oriented towards batch processing although later versions incorporated enhancements timesharing online transaction processing environments systems running gcos today use mainly batch oltp backend enterprise server although gcos basic architecture similar ibm 360 earlier ibm 7090 series abandoned ibm 360 subsequent operating systems competed also heavily influenced projects medinet multics wwmccs inherited strong security structure consequence hardware software features combine render operating system unusually secure operating system generation class multics influenced design hardware gate-oriented secure transfer-of-control instructions hardware-enforced system security levels similar famous multics rings operational environments wwmccs drove development special security features allow secure hosting classified information compartmentalization time separate versions gcos system special security features turned maintained specifically government customers gcos process-oriented os process hosts one execution threads executes virtual memory space virtual memory divided segments arbitrary size reminiscent multics segments second level address translation converts pure virtual addresses pageable addresses converted real addresses main memory backing store segments pages constructs include hardware-enforced security parameters top-level virtual memory architecture also simplifies sharing code data secure fashion way reminiscent multics gcos requires specific hardware designed operating system although recent machines capable running os emulation hardware originally much common multics hardware much mainframe equipment could switched gcos mode multics mode turn dial much peripheral equipment used gcos shared great deal multics although front-end network processors different two systems program languages available gcos included gcos algol algol-68 cobol snobol jovial apl fortran 68 coral 66 fortran 77 b become accustomed almost universal terminology units storage modern terminology applies across various operating systems computer vendors part everyday conversation terms like megabyte gigabyte mean much everyone terms like mebibyte gibibyte formally standardised however gcos8 system pre-dates mono-culture colourful units follows note system byte contains 9 bits values ranging 000 777 0–511 unlike usual 8-bit-bytes values ranging 00 ff 0-255 due 36-bit cpu architecture permanent file sizes specified llinks 1280 bytes temporary file sizes specified links 15,360 bytes since early 1970s gcos 3 gcos 8 disk drives used logical block addressing lba
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Operating systems
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server side includes server side includes ssi simple interpreted server-side scripting language used almost exclusively web useful including contents one files web page web server using codice_1 directive could commonly common piece code throughout site page header page footer navigation menu ssi also contains control directives conditional features directives calling external programs supported apache litespeed nginx iis well w3c jigsaw roots ncsa httpd order web server recognize ssi-enabled html file therefore carry instructions either filename end special extension default codice_2 codice_3 codice_4 server configured allow set execution bit file simple programming language ssi supports one type text control flow rather simple choice supported loops natively supported done recursion using include using http redirect simple design language makes easier learn use server-side scripting languages complicated server-side processing often done one feature-rich programming languages ssi turing complete ssi simple syntax codice_5 directives placed html comments ssi enabled users see ssi directives page unless look source note syntax allow spaces leading directive apache tutorial ssi stipulates format requires space character -- closes element web page containing daily quotation could include quotation placing following code file web page one change codice_6 file pages include file display latest daily quotation inclusion limited files may also text output program value system variable current time following ssi directives times ncsa httpd 1990s supported implementations control directives later added ssi include ubiquitous if-elif-else-endif flow control variable writing well exotic features like loops found implementations
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Programming language topics
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code 2001 film code english-language finnish documentary linux 2001 featuring influential people free software movement free open-source advocates programmers film
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Operating systems
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cloud robotics cloud robotics field robotics attempts invoke cloud technologies cloud computing cloud storage internet technologies centred benefits converged infrastructure shared services robotics connected cloud robots benefit powerful computation storage communication resources modern data center cloud process share information various robots agent machines smart objects humans etc. humans also delegate tasks robots remotely networks cloud computing technologies enable robot systems endowed powerful capability whilst reducing costs cloud technologies thus possible build lightweight low cost smarter robots intelligent brain cloud brain consists data center knowledge base task planners deep learning information processing environment models communication support etc cloud robots potentially least six significant components funded european union seventh framework programme research technological development projects specifically explore field cloud robotics goal roboearth allow robotic systems benefit experience robots paving way rapid advances machine cognition behaviour ultimately subtle sophisticated human-machine interaction roboearth offers cloud robotics infrastructure roboearth ’ world-wide-web style database stores knowledge generated humans – robots – machine-readable format data stored roboearth knowledge base include software components maps navigation e.g. object locations world models task knowledge e.g. action recipes manipulation strategies object recognition models e.g. images object models roboearth cloud engine includes support mobile robots autonomous vehicles drones require lots computation navigation rapyuta open source cloud robotics framework based roboearth engine developed robotics researcher ethz within framework robot connected rapyuta secured computing environment rectangular boxes giving ability move heavy computation cloud addition computing environments tightly interconnected high bandwidth connection roboearth knowledge repository myrobots service connecting robots intelligent devices internet regarded social network robots smart objects i.e facebook robots socialising collaborating sharing robots benefit interactions sharing sensor information giving insight perspective current state ros robot operating system provides eco-system support cloud robotics ros flexible distributed framework robot software development collection tools libraries conventions aim simplify task creating complex robust robot behaviour across wide variety robotic platforms library ros pure java implementation called rosjava allows android applications developed robots since android booming market billion users would significant field cloud robotics davinci project proposed software framework seeks explore possibilities parallelizing robotics algorithms map/reduce tasks hadoop project aims build cloud computing environment capable providing compute cluster built commodity hardware exposing suite robotic algorithms saas share data co-operatively across robotic ecosystem initiative available publicly c2ro c2ro cloud robotics platform processes real-time applications collision avoidance object recognition cloud previously high latency times prevented applications processed cloud thus requiring on-system computational hardware e.g graphics processing unit gpu c2ro published peer-reviewed paper ieee pimrc17 showing platform could make autonomous navigation ai services available robots- even limited computational hardware e.g raspberry pi cloud c2ro eventually claimed first platform demonstrate cloud-based slam simultaneous localization mapping robobusiness september 2017 noos cloud robotics service providing centralised intelligence robots connected service went live december 2017 using noos-api developers could access services computer vision deep learning slam noos developed maintained ortelio ltd. rocos centralized cloud robotics platform provides developer tooling infrastructure build test deploy operate automate robot fleets scale founded october 2017 platform went live january 2019 though robots benefit various advantages cloud computing cloud solution robotics research development cloud robotics following potential issues challenges term cloud robotics first appeared public lexicon part talk given james kuffner 2010 ieee/ras international conference humanoid robotics entitled cloud-enabled robots early days robot development common computation done computer separated actual robot mechanism connected wires power control wireless communication technology developed new forms experimental remote brain robots developed controlled small onboard compute resources robot control safety wirelessly connected powerful remote computer heavy processing term cloud computing popularized launch amazon ec2 2006 marked availability high-capacity networks low-cost computers storage devices well widespread adoption hardware virtualization service-oriented architecture correspondence popular science july 2006 kuffner wrote robot programmed successfully learned perform task could share model relevant data cloud-connected robots publications events related cloud robotics chronological order
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Distributed computing architecture
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disaster recovery business continuity auditing given organizations increasing dependency information technology run operations business continuity planning covers entire organization disaster recovery focuses auditing documents covering organization business continuity disaster recovery plans provides third-party validation stakeholders documentation complete contain material misrepresentations lack completeness result overlooking secondary effects vastly increased work-at-home overloads incoming recovery site telecommunications capacity bi-weekly payroll critical within first 48 hours causing perceived problems ever recovering complicated governmental possibly union reaction often used together terms business continuity disaster recovery different business continuity refers ability business continue critical functions business processes occurrence disaster whereas disaster recovery refers specifically information technology data-centric functions business subset business continuity primary objective protect organization event part operations and/or computer services rendered partially completely unusable minimizing downtime data loss disaster recovery measured terms two concepts auditor examines assess maximize effectiveness disaster recovery plans effective updated frequently adequate records need retained organization auditor examines records billings contracts verify records kept one record current list organization hardware software vendors list made periodically updated reflect changing business practice copies stored site made available accessible require auditor tests procedures used meet objective determine effectiveness disaster recovery plan drp documented process set procedures execute organization disaster recovery processes recover protect business infrastructure event disaster comprehensive statement consistent actions taken disaster disaster could natural environmental man-made man-made disasters could intentional example act terrorist unintentional accidental breakage man-made dam although one-size-fits-all plan three basic strategies latter may include securing proper insurance policies holding lessons learned brainstorming session business continuity plan bcp comprehensive organizational plan includes disaster recovery plan consists five component plans first three business resumption occupant emergency continuity operations plans deal infrastructure incident management plan imp deal infrastructure since establishes structure procedures address cyber attacks organization ’ systems generally represent agent activating disaster recovery plan leaving disaster recovery plan bcp component interest like every insurance plan benefits obtained proper planning including according geoffrey h. wold disaster recovery journal entire process involved developing disaster recovery plan consists 10 steps initial testing plan done sections normal business hours minimize disruptions subsequent tests occur normal business hours types tests include checklist tests simulation tests parallel tests full interruption tests due high cost various plans without critics dell identified five common mistakes organizations often make related bcp/dr planning auditor determines adequacy company insurance coverage particularly property casualty insurance review company insurance policies research among items auditor needs verify scope policy including stated exclusions amount coverage sufficient cover organization ’ needs policy current force auditor also ascertains review ratings assigned independent rating agencies insurance company companies providing coverage financial viability cover losses event disaster effective dr plans take account extent company responsibilities entities ability fulfill commitments despite major disaster good dr audit include review existing moa contracts ensure organization legal liability lack performance event disaster unusual circumstance minimized agreements pertaining establishing support assisting recovery entity also outlined techniques used evaluating area include examination reasonableness plan determination whether plan takes factors account verification contracts agreements reasonableness documentation outside research auditor must verify planning ensures management recovery team effective communication hardware contact information internal communication external issues business partners key customers audit techniques include procedures sustain staff round-the clock disaster recovery effort included good disaster recovery plan procedures stocking food water capabilities administering cpr/first aid dealing family emergencies clearly written tested generally accomplished company good training programs clear definition job responsibilities review readiness capacity plan often includes tasks inquires personnel direct physical observation examination training records certifications auditor must review procedures take account possibility power failures situations non-it nature
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Computer security
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ntp server misuse abuse ntp server misuse abuse covers number practices cause damage degradation network time protocol ntp server ranging flooding traffic effectively ddos attack violating server access policy ntp rules engagement one incident branded ntp vandalism open letter poul-henning kamp router manufacturer d-link 2006 term later extended others retroactively include incidents however evidence problems deliberate vandalism usually caused shortsighted poorly chosen default configurations deliberate form ntp server abuse came note end 2013 ntp servers used part amplification denial-of-service attacks ntp servers would respond single monlist udp request packet packets describing 600 associations using request spoofed ip address attackers could direct amplified stream packets network resulted one largest distributed denial-of-service attacks known time troublesome problems involved ntp server addresses hardcoded firmware consumer networking devices major manufacturers oems produced hundreds thousands devices using ntp coupled customers almost never upgrading firmware devices ntp query storms problems persist long devices service one particularly common ntp software error generate query packets short less five second intervals response received might technically reasonable send initial packets short intervals essential health network client connection re-attempts generated logarithmically exponentially decreasing rates prevent denial service protocol exponential logarithmic backdown applies connectionless protocol extension many portions connection-based protocols examples backing method found tcp specification connection establishment zero-window probing keepalive transmissions october 2002 one earliest known cases time server misuse resulted problems web server trinity college dublin traffic ultimately traced misbehaving copies program called tardis thousands copies around world contacting web server obtaining timestamp via http ultimately solution modify web server configuration deliver customized version home page greatly reduced size return bogus time value caused clients choose different time server updated version tardis later released correct problem first widely known case ntp server problems began may 2003 netgear hardware products flooded university wisconsin–madison ntp server requests university personnel initially assumed malicious distributed denial service attack took actions block flood network border rather abating ddos attacks flow increased reaching 250,000 packets-per-second 150 megabits per second june subsequent investigation revealed four models netgear routers source problem found sntp simple ntp client routers two serious flaws first relies single ntp server university wisconsin–madison whose ip address hard-coded firmware second polls server one second intervals receives response total 707,147 products faulty client produced netgear released firmware updates affected products dg814 hr314 mr814 rp614 query netgear servers poll every ten minutes give five failures update fixes flaws original sntp client solve larger problem consumers never update router firmware particularly device seems operating properly university wisconsin–madison ntp server continues receive high levels traffic netgear routers occasional floods 100,000 packets-per-second netgear donated 375,000 university wisconsin–madison division information technology help identifying flaw also 2003 another case forced ntp servers australian commonwealth scientific industrial research organisation csiro national measurement laboratory close public traffic shown come bad ntp implementation smc router models ip address csiro server embedded firmware smc released firmware updates products 7004vbr 7004vwbr models known affected 2005 poul-henning kamp manager danish stratum 1 ntp server available general public observed huge rise traffic discovered 75 90 originating d-link router products stratum 1 ntp servers receive time signal accurate external source gps receiver radio clock calibrated atomic clock convention stratum 1 time servers used applications requiring extremely precise time measurements scientific applications stratum 2 servers large number clients home networking router meet either criteria addition kamp server access policy explicitly limited servers directly connected danish internet exchange dix direct use stratum 1 servers d-link routers resulted huge rise traffic increasing bandwidth costs server load many countries official timekeeping services provided government agency nist u.s. since danish equivalent kamp provides time service pro bono publico return dix agreed provide free connection time server assumption bandwidth involved would relatively low given limited number servers potential clients increased traffic caused d-link routers dix requested pay yearly connection fee approximately kamp contacted d-link november 2005 hoping get fix problem compensate time money spent tracking problem bandwidth charges caused d-link products company denied problem accused extortion offered amount compensation kamp asserted cover expenses 7 april 2006 kamp posted story website story picked slashdot reddit news sites going public kamp realized d-link routers directly querying stratum 1 time servers violating access policies least 43 process april 27 2006 d-link kamp announced amicably resolved dispute 20 years eth zurich provided open access time server swisstime.ethz.ch operational time synchronization due excessive bandwidth usage averaging upwards 20 gb day become necessary direct external usage public time server pools ch.pool.ntp.org misuse caused mostly it-providers synchronizing client infrastructures made unusually high demands network traffic thereby causing eth take effective measures availability swisstime.ethz.ch changed closed access access server blocked entirely ntp protocol december 2016 operator community ntppool.org noticed significant increase ntp traffic starting december 13 investigation showed snapchat application running ios prone querying ntp servers hardcoded third party ios ntp library request snapchat-owned domain followed ntp request flood snap inc. contacted developers resolved problem within 24 hours notification update application apology assist dealing load generated snap also contributed timeservers australia south america ntp pools positive side effect ntp library used open source error-prone default settings improved feedback ntp community firmware tp-link wi‑fi extenders 2016 2017 hardcoded five ntp servers including fukuoka university japan australia new zealand ntp server pools would repeatedly issue one ntp request five dns requests every five seconds consuming 0.72 gb per month per device excessive requests misused power internet connectivity check displayed device connectivity status web administration interface issue acknowledged tp-link branch japan pushed company redesign connectivity test issue firmware updates addressing issue affected devices affected devices unlikely install new firmware wifi extenders tp-link install firmware updates automatically notify owner firmware update availability tp-link firmware update availability also varies country even though issue affects wifi range extenders sold globally servers fukuoka university reported shutdown sometime february april 2018 removed ntp public time server lists incidents became clear apart stating server access policy technical means enforcing policy needed one mechanism provided extending semantics reference identifier field ntp packet stratum field 0 january 2006 rfc 4330 published updating details sntp protocol also provisionally clarifying extending related ntp protocol areas sections 8 11 rfc 4330 particular relevance topic kiss-o'-death packet good network citizen best practices security considerations section 8 introduces kiss-o'-death packets new requirements ntp protocol work retroactively old clients implementations earlier version protocol recognize kod act time good technical means counteract misuse ntp servers 2015 possible attacks network protocol time network time security ntp internet draft codice_1 proposed using transport layer security implementation june 21 2019 cloudflare started trial service around world based previous internet draft
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Computer security
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riskiq riskiq cyber security company based san francisco california provides cloud-based software service saas organizations detect phishing fraud malware online security threats company co-founded 2009 lou manousos chris kiernan david pon received 10 million series funding summit partners february 2013 25 million series b funding battery ventures may 2014 riskiq member cloud security alliance csa isaca riskiq monitors advertising networks malware malvertising spyware also provides mobile app security services may 2018 standard bank deployed riskiq software automate threat analysis brand infringement cybercrime web-based attacks digital presence
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Computer security
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link time computer science link time refers period time creation computer program linker applied program link time occurs compile time runtime program executed common speak link time operations operations performed linker link time requirements programming language requirements must met compiled source code successfully linked operations performed link time usually include fixing addresses externally referenced objects functions various kinds cross module checks e.g type checks externally visible identifiers languages instantiation templates optimizing compilers delay code generation link time information complete program available resolving external variables program also done link time definition programming language may specify link time requirements source code must meet successfully compiled e.g maximum number characters externally visible identifier must considered significant programming languages may necessary compilation linking occur runtime
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Programming language topics
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apache avro avro row-oriented remote procedure call data serialization framework developed within apache hadoop project uses json defining data types protocols serializes data compact binary format primary use apache hadoop provide serialization format persistent data wire format communication hadoop nodes client programs hadoop services avro uses schema structure data encoded two different types schema languages one human editing avro idl another machine-readable based json similar thrift protocol buffers require running code-generation program schema changes unless desired statically-typed languages apache spark sql access avro data source avro object container file consists file header consists data blocks avro specifies two serialization encodings binary json applications use binary encoding smaller faster debugging web-based applications json encoding may sometimes appropriate avro schemas defined using json schemas composed primitive types null boolean int long float double bytes string complex types record enum array map union fixed simple schema example data avro might stored corresponding schema meaning serialized item read without knowing schema ahead time serialization import avro.schema avro.datafile import datafilereader datafilewriter avro.io import datumreader datumwriter schema avro.schema.parse open user.avsc rb .read need know schema write according 1.8.2 apache avro writer datafilewriter open users.avro wb datumwriter schema writer.append name alyssa favorite_number 256 writer.append name ben favorite_number 7 favorite_color red writer.close file users.avro contain schema json compact binary representation data od -v -t x1z users.avro 0000000 4f 62 6a 01 04 14 61 76 72 6f 2e 63 6f 64 65 63 obj ... avro.codec 0000020 08 6e 75 6c 6c 16 61 76 72 6f 2e 73 63 68 65 6d .null.avro.schem 0000040 61 ba 03 7b 22 74 79 70 65 22 3a 20 22 72 65 63 a.. type rec 0000060 6f 72 64 22 2c 20 22 6e 61 6d 65 22 3a 20 22 55 ord name u 0000100 73 65 72 22 2c 20 22 6e 61 6d 65 73 70 61 63 65 ser namespace 0000120 22 3a 20 22 65 78 61 6d 70 6c 65 2e 61 76 72 6f example.avro 0000140 22 2c 20 22 66 69 65 6c 64 73 22 3a 20 5b 7b 22 fields 0000160 74 79 70 65 22 3a 20 22 73 74 72 69 6e 67 22 2c type string 0000200 20 22 6e 61 6d 65 22 3a 20 22 6e 61 6d 65 22 7d name name 0000220 2c 20 7b 22 74 79 70 65 22 3a 20 5b 22 69 6e 74 type int 0000240 22 2c 20 22 6e 75 6c 6c 22 5d 2c 20 22 6e 61 6d null nam 0000260 65 22 3a 20 22 66 61 76 6f 72 69 74 65 5f 6e 75 e favorite_nu 0000300 6d 62 65 72 22 7d 2c 20 7b 22 74 79 70 65 22 3a mber type 0000320 20 5b 22 73 74 72 69 6e 67 22 2c 20 22 6e 75 6c string nul 0000340 6c 22 5d 2c 20 22 6e 61 6d 65 22 3a 20 22 66 61 l name fa 0000360 76 6f 72 69 74 65 5f 63 6f 6c 6f 72 22 7d 5d 7d vorite_color 0000400 00 05 f9 a3 80 98 47 54 62 bf 68 95 a2 ab 42 ef ... gtb.h ... b. 0000420 24 04 2c 0c 41 6c 79 73 73 61 00 80 04 02 06 42 ..alyssa ... b 0000440 65 6e 00 0e 00 06 72 65 64 05 f9 a3 80 98 47 54 en ... red ... gt 0000460 62 bf 68 95 a2 ab 42 ef 24 b.h ... b. 0000471 deserialization reader datafilereader open users.avro rb datumreader need know schema read user reader reader.close outputs though theoretically language could use avro following languages apis written addition supporting json type protocol definitions avro includes experimental support alternative interface description language idl syntax known avro idl previously known genavro format designed ease adoption users familiar traditional idls programming languages syntax similar c/c++ protocol buffers others apache avro logo defunct british aircraft manufacturer avro originally a.v roe company football team avro f.c uses logo
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Internet protocols
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vpn blocking vpn blocking technique used block encrypted protocol tunneling communications methods used virtual private network vpn systems often used large organizations national governments corporations act tool computer security internet censorship preventing use vpns bypass network firewall systems blocking vpn access done different ways ports used common vpn tunneling protocols pptp l2tp establish connections transfer data closed system administrators prevent use certain networks similarly website prohibit access content blocking access ip addresses known belong vpn providers governments known block access overseas ip addresses since vpn use involve connecting remote hosts operate government jurisdiction organizations ramped efforts block vpn access bypasses firewalls vpn providers responded utilizing sophisticated techniques make connections less conspicuous instance chinese government began using deep packet inspection identify vpn protocols golden frog began scrambling openvpn packet metadata popular vyprvpn service attempt avoid detection chinese internet users started reporting unstable connections may 2011 using vpns connect overseas websites services apple app store universities businesses began issuing notices stop using tools circumvent firewall late 2012 companies providing vpn services claimed great firewall china became able learn discover block encrypted communications methods used number different vpn systems 2017 telecommunications carriers china instructed government block individuals use vpns february 2018 government iran began blocking access non-government sanctioned vpns march 2013 months prior 2013 elections prosecute users violating state laws take offenders national courts supervision judiciary service use vpns approved government reportedly led surveillance inspection private data july 2017 state duma passed bill requiring internet providers block websites offer vpns order prevent spreading extremist materials internet.. unclear exactly russia plans implement new regulation though seems like federal security service fsb isps tasked identifying cracking vpns russian internet users also reported block expressvpn vpn service november 2017 bbc made clear russia banned vpn usage entirely vpn usage banned attempting access sites already blocked roskomnadzor russia governing body telecommunications mass media communications using vpn business personal reasons access legal sites russia permitted government syria activated deep packet inspection uprising 2011 order block vpn connections censorship targeted different vpn protocols like openvpn l2tp pptp government egypt activated deep packet inspection egyptian revolution 2011 order block vpn connections block access objection media newspaper sites censorship targeted different vpn protocols like openvpn l2tp ikev2 pptp sites government turkey using deep packet inspection detecting possible openvpn connections attempt stop unauthorized access users outside us hulu began blocking users accessing site ip addresses linked vpn services april 2014 however company also restricted access legitimate u.s.-based users using vpns security reasons vpn providers vikingvpn nordvpn torguard stated would seek ways address issue customers speaking directly hulu resolution rolling dedicated ip addresses respectively netflix came pressure major film studios september 2014 block vpn access 200,000 australian subscribers using netflix despite available yet australia vpn access netflix like streaming services allowed users view content securely country netflix users also used vpns means bypassing throttling efforts made service providers verizon also important note vpns might slow internet connection trying stream netflix however cases using vpn might improve connection isp throttling netflix traffic june 2018 netflix vpn proxy ban still active ceo netflix reed hastings made comment 2016 vpn market whole “ ’ small quite vocal minority ’ really inconsequential us. ” bbc started blocking users connecting via vpns october 2015 bbc able detect vpn connections monitoring number simultaneous connections coming ip address number connections ip becomes abnormal bbc block future connections offending ip address iplayer remains unavailable uk tv licence holders connecting eu countries bbc said interested able allow uk licence fee payers access bbc iplayer holiday welcome european union regulation help make feasible wikipedia often blocks editing vpns many vpns use open proxies wikipedia allow open proxies however still view articles vpns use proxies use closed proxies usually still edit wikipedia
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Computer security
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gtube gtube generic test unsolicited bulk email 68-byte test string used test anti-spam systems particular based spamassassin spamassassin carries antispam score 1000 default would sufficient trigger installation contents string follows placed message body rfc 5322 compliant email message without linebreaks whitespaces exist varieties notably naitube carry variable weight gtphish trigger specifically phishing mail used mcafee implementation spamassassin
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Computer security
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data portability data portability concept protect users data stored silos walled gardens incompatible one another i.e closed platforms thus subjecting vendor lock-in data portability requires common technical standards facilitate transfer one data controller another thus promoting interoperability data portability applies personal data involves access personal data without implying data ownership per se global level proponents seeing protection digital data human right thus emerging civil society draft declaration one finds mention following concepts statutes right privacy internet right digital data protection rights consumer protection internet united nations guidelines consumer protection regional level least three main jurisdictions data rights seen differently china/india united states european union latter personal data given special protection 2018 general data protection regulation gdpr gdpr thus became fifth 24 types legislation listed annex 1 table existing proposed european directives regulations relation data personal data basis behavioral advertising early 21st century value began grow exponentially least measured market capitalization major platforms holding personal data respective users european union regulators reacted perceived power imbalance platforms users although much still hinges terms consent given users platforms concept data portability comprises attempt correct perceived power imbalance introducing element competition allowing users choose among platforms right data portability laid european union general data protection regulation gdpr passed april 2016 regulation apply data processors whether inside outside eu process data individuals physically located within eu member state earlier european data protection supervisor stated data portability could let individuals benefit value created use personal data european-level article 29 data protection working party held consultation english lasting end january 2017 guidelines faq right data portability contain call action april 2017 new guidelines published article 29 working party website french national data supervisor cnil hosted discussion french current participants offer opinions legislation provides benefits companies many users although united kingdom voted withdraw eu intends incorporate much gdpr legislation include data portability ... gdpr contains noteworthy innovations – instance… introduction new right data portability likewise switzerland nation-state related eu bilateral basis efta member state trend moving direction swiss view officially published march 2018 document pdf cooperative proposed right data portability anchored constitution swiss confederation law passed includes data portability cooperative called midata.coop besides proposing legislation offer users place store data longer term swiss may consider data portability gdpr given gdpr raise compliance costs eu-based companies unlikely eu would tolerate situation third-party countries swiss companies would held standard order keep competition fair legal terms involved adequacy reciprocity always tricky legislators regulate right level precision everyone understands technology evolve faster law far european union formalized expectations around data portability requiring data structured commonly used machine-readable interoperable format touches least two distinct technical requirements effective interoperability list rights grown data portability right slightly different right access personal data see gdpr seventh item list cited immediately right access mandates data subject gets see personal data old eu data protection directive used require explicitly cases data provided intelligible form interpreted far human readable requirement still somewhat present eu general data protection regulation implicitly conjunction recital_ law since right portability mostly concerned reuse services i.e likely automated could human readable raw format would inappropriate effective data portability intermediate level might need sought addition gdpr limits scope data portability cases processing made basis either consent data subject performance contract data portability right related right explanation i.e automated decisions made legal effect significant impact individual data subjects display algorithm one way decision tree right however found useful empirical study right explanation related right evaluated basis automated processing shown last item list shown gabel hickman includes decisions based profiling right included eu data protection directive 1995 much enforcement followed article wired emphasised poignancy discussion issue discussed bygrave hildebrandt claimed one important transparency rights era machine learning big data contrary hildebrandt high expectations 2012 four years later many revisions gdpr text finalized three well-known authors contest whether right explanation still exists gdpr see united states description related developments seminal book law professor frank pasquale relevant passages reviewed electronic privacy information center epic even u.s. defense advanced research projects agency darpa explainable ai xai program cited critically blogger artur kiulian several papers published topics 2016 first goodman flaxman outlines development right explanation pasquale think approach goes far enough stated blog entry london school economics lse fact lse whole series algorithmic accountability one entry feb. 2016 notable ones joshua kroll mireille hildebrandt another 2016 paper one published katarinou et al. includes remarks right appeal individuals would right appeal machine decision made human third 2016 paper one co-authored mittelstadt et al. maps literature relates gdpr pages 13–14 fourth paper one co-authored wachter mittelstadt floridi refutes idea right might included gdpr proposes limited ‘ right informed ’ instead calls creation agency implement transparency requirement paper edwards veale claims right unlikely apply cases 'algorithmic harms attracting recent media attention insufficient attention paid computer science literature explanation gdpr provisions data protection impact assessments data portability might help almost two years later paper appeared challenges earlier papers especially wachter mittelstadt floridi sides atlantic recent activity pertaining ongoing debate early 2016 experts artificial intelligence uk government officials met number meetings developed data science ethical framework november 7 2016 event held brussels organized mep marietje schaake european parliament described danah boyd eleven days later new york university conference fairness accountability transparency machine learning principles accountable algorithms social impact statement algorithms articulated placed online discussion mid-december ieee came document whose editing backed public comments invited march 2017 ethically aligned design later 2017 data portability analysed professors data protection central innovation new gdpr
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Computer architecture
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warchalking warchalking drawing symbols public places advertise open wi-fi network inspired hobo symbols warchalking marks conceived group friends june 2002 publicised matt jones designed set icons produced downloadable document containing within days jones publishing blog entry warchalking articles appeared dozens publications stories appeared several major television news programs around world word formed analogy wardriving practice driving around area car detect open wi-fi nodes term turn based wardialing practice dialing many phone numbers hoping find modem found wi-fi node warchalker draws special symbol nearby object wall pavement lamp post offering wi-fi service might also draw symbol advertise availability wi-fi location whether commercial personal
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Computer security
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norman safeground norman safeground develops sells data security software anti-virus anti-spam anti-spyware backup local support company headquarters oslo norway norman safeground global partner-network main market europe norman competes antivirus industry avira bullguard f-secure frisk kaspersky mcafee panda security sophos symantec trend micro among others norman founded 1 october 1984 oslo company pioneer proactive security software solutions forensics malware tools utilizing patented sandbox technology 1995 norman acquired 50 percent ibas norwegian data recovery company company listed oslo stock exchange 11 august 1997 norman asa bought remaining 50 percent stake ibas 1999 2004 two companies de-merged ibas listed separate entity oslo stock exchange norman de-listed oslo stock exchange october 2009 acquired private equity fund fsn capital partners late 2012 norman asa split two companies br norman safeground focusing consumers smes norman shark focusing enterprise market intrusion prevention solutions services november 2014 norman safeground acquired avg technologies
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Computer security
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suexec apache suexec feature apache web server allows users run common gateway interface cgi server side includes ssi applications different user normally web server processes run default web server user often wwwrun www-data apache nobody suexec feature consists module web server binary executable acts wrapper suexec introduced apache 1.2 often included default apache package provided linux distributions client requests cgi suexec activated call suexec binary wraps cgi scripts executes user account server process virtual host defined virtual host directive additionally suexec perform multi-step check executed cgi ensure security server including path-checks limit permitted commands etc user alice website including common gateway interface script files codice_1 common web root directory name folder accessed codice_2 user bob views alice webpage requires apache run one cgi scripts instead running scripts wwwrun results need scripts readable executable wwwrun group file owned group users otherwise scripts codice_3 wrapped using suexec run alice user id resulting higher security eliminating need make scripts readable executable users everyone wwwrun group instead alice needs able run script
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Computer security
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kronos malware kronos type banking malware first reported 2014 sold 7,000 similar zeus focused stealing banking login credentials browser sessions 2015 attacks focused british banks august 2017 british security researcher marcus hutchins aka 'malwaretech previously notable involvement stopping may 2017 wannacry ransomware attack arrested fbi whilst visiting united states alleged created software 2014 sold 2015 via alphabay forums
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Computer security
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es pevm es pevm ес пэвм soviet clone ibm pc 1980s es pevm models lineup also included analogues ibm pc xt ibm pc ibm xt/370 computers software adapted minsk belarus scientific research institute electronic computer machines нии эвм manufactured minsk well minsk production group computing machinery минское производственное объединение вычислительной техники мпо вт first models es pevm es-1840 es-1841 es-1842 unlike ibm pc two units system unit floppy drives unit models used backplane instead main board although system bus compatible isa bus used different type connector ibm pc expansion cards could installed es pevm later models es-1843 es-1849 etc fully compatible ibm pc xt ibm pc unlike ibm pc using intel 8088 processor early es pevm models used k1810vm86 processor 16-bit bus clock frequency 5 mhz processor placed separate board early versions board socket floating point coprocessor following boards produced es-1840 es-1841 volume production number models computers shipped alphados entirely russified version ms-dos/pc-dos 2.x 3.x commands entered russian example сменкат chdir files file extensions also russian атриб.исп attrib.exe operating system used main code page hardwired display rom compatible neither cp 866 cp 855 although partially iso/iec 8859-5 early models es pevm prone failures due manufacturing defects mean time failures mtbf around 350 hours
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Computer architecture
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caller id caller id caller identification cid also called calling line identification clid calling line identification cli calling number delivery cnd calling number identification cnid calling line identification presentation clip call display telephone service available analog digital telephone systems including voip transmits caller telephone number called party telephone equipment call set caller id service may include transmission name associated calling telephone number service called cnam service first defined 1993 international telecommunication union telecommunication standardization sector itu-t recommendation q.731.3 recipient may inspect information answering call display telephone set separately attached device digital displays cable television sets telephone television service provided vendor caller id information may inaccurate false forged hence caller id information fully relied upon identify caller.. root cause lack authenticity accountability transmission telephone identities countries terms caller display calling line identification presentation clip call capture calling line identity used call display predominant marketing name used canada although customers still refer colloquially caller id idea cnid service pots subscribers originated automatic number identification ani part toll free number service united states however cnid ani thing ani originally term given system identified telephone number placing call non-electronic central office switch previous calling number could identified electronically caller id made two separate pieces information calling number billing subscriber name available call made given name name passed number different methods example caller name may datafilled originating switch case sent along number commonly database accessed receiving switch order match number name name exist city state province designation may sent databases may shared among several companies paying every time name extracted reason mobile phone callers appear wireless caller location phone number registered e.g cell phone ga cell phone registered georgia u.s.a. vary based company owns block numbers provider number may ported additionally nothing ensures number sent switch actual number call originated telephone switch initiating call may send digit string desired caller id telephone switch therefore operating entity must also trusted provide secure authentication displayed caller id also depends equipment originating call call originates pots line standard loop start line caller id provided service provider local switch since network connect caller callee phone answered generally caller id signal altered caller service providers however allow caller block caller id presentation vertical service code *67 call placed behind private branch exchange pbx options typical telephony environment pbx connects local service provider primary rate interface pri trunks generally although absolutely service provider simply passes whatever calling line id appears pri access trunks transparently across public switched telephone network pstn opens opportunity pbx administrator program whatever number choose external phone number fields ip phone services itsps internet telephony service providers support pstn gateway installations throughout world gateways egress calls local calling area thus avoiding long distance toll charges itsps also allow local user number located foreign exchange new york caller could los angeles number example user places call calling line id would los angeles number although actually located new york allows call return without incur long distance calling charges cellphones biggest issue appears passing calling line id information network cellphone companies must support interconnecting trunks significant number wireline pstn access carriers cli localisation describes process presenting localised cli calling line identity recipient telephone call cli localisation utilised various organisations including call centres debt collectors insurance companies cli localisation allows companies increase contact rate increasing chance called party answer phone call localised cli displayed called party device call perceived local recognisable caller rather withheld unknown premium rate number presented telephone number adjusted depending area code dialed number 1968 theodore george ted paraskevakos working communications engineer sita athens greece began developing system automatically identify telephone caller call recipient several attempts experiments developed method caller number transmitted receiver device method basis modern-day caller id technology 1969 1975 paraskevakos issued twenty separate patents related automatic telephone line identification since significantly predated similar patents appear prior art later united states patents issued kazuo hashimoto carolyn a. doughty 1971 paraskevakos working boeing huntsville alabama constructed reduced practice transmitter receiver representing world first prototypes caller-identification devices installed peoples telephone company leesburg alabama demonstrated several telephone companies original historic working models still possession paraskevakos patents related devices paraskevakos also proposed send alphanumeric information caller name receiving apparatus make banking telephone feasible also proposed identify calling telephone special code e.g. pf public phone ho home phone office phone pl police may 1976 kazuo hashimoto prolific japanese inventor one thousand patents worldwide first built prototype caller id display device could receive caller id information work caller id devices early prototypes received smithsonian institution national museum american history 2000 u.s. patent 4,242,539 filed originally may 8 1976 resulting patent re-examined patent office successfully licensed major telecommunications computer companies world initially operating telephone companies wanted caller id function performed central office voice announcement charged per-call basis john harris employee northern telecom telephone set manufacturing division london ontario promoted idea caller id telephone set display telephone coded eccs enhanced custom calling services video prototype used leverage feature central office telephone set 1977 brazilian inventor valdir bravo salinas filed patent application caller id device brazilian patent trademarks office inpi patent issued 1982 patent pi7704466 first patent ever issued caller id equipment brazil later 1980 two brazilian inventors joão da cunha doya nélio josé nicolai filed different patent applications caller id devices doya ’ application filed may 2 1980 issued patent pi8003077 nicolai ’ application filed july 2 1980 rejected copy salinas invention 1981 another application caller id equipment filed inpi josé daniel martin catoira afonso feijó da costa ribeiro neto application granted patent issued patent pi8106464 first market trial caller id custom local area signaling services conducted bell atlantic may 1984 bell communications research bellcore named service caller id regional bell operating companies later adopted name eventually became generally accepted name united states planning trial initiated team bell laboratories western electric bell system divestiture participation bell atlantic purpose trials assess revenue potential services depend deployment common channel signaling network needed transmit calling number originating terminating central offices trial results analyzed bellcore members original team 1987 bell atlantic verizon communications conducted another market trial hudson county new jersey followed limited deployment bellsouth first company deploy caller id december 1988 memphis tennessee full deployment nine-state region next four years bell atlantic second local telephone company deploy caller id new jersey hudson county followed us west communications centurylink 1989 1995 bellcore released another type modulation similar bell 202 became possible transmit caller id information even provide call-disposition options user already telephone service became known markets call waiting id combined call-disposition options call waiting deluxe technically referred analog display services interface call waiting deluxe bellcore telcordia technologies term type ii caller id disposition options class-based pots-telephone calling feature works combining services call waiting caller id also introduces options feature conjunction certain screen-based telephones capable equipment gives telephone user option data checksum united states caller id information sent called party telephone switch analog data stream similar data passed two modems using bell 202 modulation first second rings telephone unit still hook telephone call answered quickly first ring caller id information transmitted recipient two types caller id number name+number number-only caller id called single data message format sdmf provides caller telephone number date time call name+number caller id called multiple data message format mdmf addition information provided sdmf format also provide directory listed name particular number caller id readers compatible mdmf also read simpler sdmf format sdmf caller id reader recognize mdmf data stream act caller id information present e.g line equipped caller id instead sending caller id first second ring systems uk use line reversal announce caller id caller id signals simply sent without announcement instead bell 202 european alternative v.23 sometimes used without 75-baud reverse channel data sent using dtmf signalling general cid transmitted origin call calling party full phone number including area code including international access code country code international call calling party name added consumer terminating central office consumer subscribed service calling name delivery automatic ss7 signalling system 7 tcap query may launched called party central office order retrieve information calling name delivery caller id equipment consumer location caller name already associated calling party line originating central office canadian systems using ccs7 automatically cases send calling name call set-up routing information time call look name associated phone number carrier instances access information third-party database database providers charge small fee access databases cnam dip fee small – less penny per call starts negotiations cnam dip fees .004 per lookup opencnam fees bit expensive .0048 per lookup avoid charges carriers report name unavailable report name city state based phone number particularly wireless callers toll-free numbers may report string tollfree number name available database smartphones use third-party mobile app name lookup third-party database telemarketing organisations often spoof caller id instances done provide central number consumers call back toll-free number rather consumers call back outbound call centre call actually originated however telemarketers block fraudulently spoof caller id prevent traced united states federal law telemarketers block send false caller id individuals bring civil suits federal communications commission fcc fine companies individuals illegally spoofing blocking caller id telemarketers used caller id marketing using toll-free number registering text string free money free plane tickets name displayed caller id internet service providers isps providing dial-up access require customer use cnid prevent abuse account unauthorised callers systems dial-up access programmed accept calls specific caller id strings mobile phone providers used caller id automatically connect voice mail call voice mail number made associated mobile phone number bypassing need enter password convenient many users spoofing practice replaced secure authentication many carriers caller id transmission implemented using different technologies standards countries united states bellcore fsk standard prevalent whereas taiwan uses etsi fsk sometimes individual service providers within country use different standards caller id converters used translate one standard another telephone equipment usually displays clid information difficulty modems notoriously problematic modems support british telecom standard hardware drivers often errors prevent clid information recognised uk telephone companies use slight variations bellcore standard clid support hit miss cnd currently available australia subscribers integrated services digital network isdn legislation section 276 australia industry code calling number display acif c522 february 2003 united states telemarketers required transmit caller id requirement went effect january 29 2004 courts ruled caller id admissible providers required fcc rules offer per-call blocking caller id customers legislation united states made caller id spoofing illegal fraudulent purposes starting mid-2017 intended culmination 2019 fcc pushed forward caller id certification implemented via methodology shaken/stir caller id blocking common term service caller prevent display calling number recipient telephone blocking number formally referred calling line identification restriction clir telecommunications regulators vary requirements use effectiveness assorted technologies prevent numbers displayed generally unlisted numbers always blocked non-published regular listed numbers usually blocked varying treatment determination call display blocking many factors desired customers inquire carefully make sure number displayed telephone service provider may also vertical service codes dialed configure blocking active calls call-by-call basis locations united states regulations allow require blocking automatic transparent caller blocking applied call-by-call basis time call made subscribers block caller id dialing special code vertical service code vsc making call north america regions code *67 1167 rotary dial united kingdom ireland 141 special code block information companies using call capture technology means equipment caller id simply display word private withheld cnid blocked caller request number actually transmitted entire telephone network presentation withheld flag set destination co expected honor flag sometimes not—especially destination phone number served isdn pri alternatively cases caller id blocked automatically released call-by-call basis dialing special code *82 north america 1470 uk see enabling similarly countries offer anonymous caller rejection rejects calls subscriber name number blocked telephone companies protect clients receiving blocked information routing anonymous calls service privacy manager caller required announce service asks called party want accept reject call telephone companies play recording caller advising called party rejection configuration often offer advice prefixing dialing *82 get call intended called party emergency services likely able show restricted number using service called calling line identification restriction override cliro using general ani services features create cat-and-mouse game type situation whereby subscribers must purchase additional services order cancel services prefixing telephone number following codes disables caller id per-call basis countries networks vary however gsm mobile networks callers may dial 31 number wish call disable countries network providers allow caller id blocking based domestic telecommunications regulations clir available external app value-added service depending operator country number prefix codes unblock caller id gsm mobile networks callers may dial *31 enable caller id subsequent calls caller id spoofing practice causing telephone network display number recipient caller id display different actual originating station many telephone services isdn pri based pbx installations voice ip services permit caller configure customized caller id information corporate settings permits announcement switchboard number customer service numbers caller id spoofing may illegal countries certain situations consumer telephone company must pay small fee caller id text transmitted call fee called cnam dip fee named dip fee consumer carrier pays fee dip originating telephone company database get caller id information several companies engage generating dip fees catering companies make large number outbound calls callerid4u pacific telecom communications group cater telemarketers generate revenue fees caller id information telemarketers enter agreement companies like callerid4u pacific telecom communications group share revenue produced telemarketing call consumers face significant barriers exiting call list often removed list calling opt-out numbers often results fast-busy call never completes consumer remains list according reports companies like callerid4u thousands phone numbers thousands ftc complaints filed month violating call registration large number phone numbers dilute number complaints company phone number
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Computer security
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system 6 system 6 also referred system software 6 graphical user interface-based operating system macintosh computers released 1988 apple computer inc. part classic mac os series operating systems system 6 included new macintosh computers succeeded system 7 1991 boxed version system 6 cost 49 introduced system 6 classed monolithic operating system features improved multifinder allows co-operative multitasking new utility called macromaker included system 6 enabled allowed users record mouse keyboard input macros macromaker unique user interface aimed look act like tape recorder macromaker criticized lack features compared microsoft automac iii already available commercially macromaker recorded locations mouse-clicks inside windows clicked exactly users soon found could used automate sophisticated programs pre-recorded clicks would miss buttons moved failed appear upon playback addition macromaker limitations recorded start end locations mouse movements precise path movements macros handle situations required macro wait period time action macromaker compatible system 7 marked introduction applescript alternative cooperative multitasking made macintosh debut march 1985 program called switcher andy hertzfeld allowed user launch multiple applications switch many programs features function correctly switcher also switcher display windows applications beside selected one included operating system available apple separate purchase system 5 system 6 feature called multifinder instead much mature widely used system 6 multifinder could enabled disabled reboot disabled finder would quit user launched another application thus freeing ram enabled system behaved nowadays familiar multitasking tradition desktop windows applications screen background system 6 included support apple imagewriter lq postscript laser printers new software drivers allowed imagewriter lq used appletalk local area networks supports use tabloid b size paper system 6 also included quickergraf originally called quickerdraw piece system software used accelerate drawing color screen images macintosh ii licensed apple radius inc programmer andy hertzfeld system 6 apple menu used launch applications current application icon upper right-hand corner menu bar cycles open applications menu system 6 supports 24 bits addressable ram random access memory allowed maximum 8 megabytes ram provision virtual memory limitations fixed system 7 version hfs file system used system 6 also volume size limit supports 2 gigabytes gb 65,536 files volume limitation increased system 7.5 first increased limit 4 gb trash known wastebasket british versions empties finder terminates multifinder running occurs soon application launches icons desktop system 6 organized single folder later operating systems instead system records whether file desktop inefficient confusing user browse desktop applications besides finder even within standard open save dialog boxes furthermore dialogs primitive mostly unchanged since 1984 lack aliases shortcuts files another limitation file management system 6 custom file folder icons also supported problems remedied system 7 maximum 15 desk accessories may installed one time including chooser scrapbook control panel system 6 uses control panel desk accessory access installed control panels imposes severe user interface limitations desk accessories installed removed within finder requires font/da mover utility system 7 also fixed control panels however contained separate files methods exist interface personalization finder allows icon assigned color desktop background limited 8x8 pixel color tiled pattern color patterns introduced system 5 standard window frames black white however many init extension files existed add color customization system 7 later allowed user change color various aspects user interface 1989 system 6 user interface need change comparison nextstep operating system time system 6 make use sound user interface presented several limitations terms file management way windows displayed initial releases system 6 unstable many third party software developers receive copies release resulting widespread compatibility problems first many common software programs microsoft excel microsoft works 4th dimension fully compatible system 6 also software bugs color manager script manager sound manager extension files apple announced 66 bugs fixed 6.0.1 update released september 1988 however major bug involving text spacing screen fonts found 6.0.1 distribution began led quick release 6.0.2 solved problem customers waited longer moving system 6 poor reputation already gained system 6 officially supported apple many different machines shipped system 6 may apple computers system 6 officially supported may nevertheless able run perhaps limitations
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Operating systems
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hmg infosec standard no.1 hmg information assurance standard no.1 usually abbreviated is1 security standard applied government computer systems uk standard used assess – suggest responses – technical risks confidentiality integrity availability government information modelling technique used standard adaptation domain based security confidentiality terms is1 apply information protectively marked may still used assess risks integrity availability information uk cabinet office security policy framework requires ict systems manage government information interconnected assessed identify technical risks is1 standard method mandated previous versions security policy framework methods may used results is1 assessment responses risks recorded using hmg information assurance standard no.2 usually abbreviated is2 concerns risk management relevant accreditation government computer systems cesg provides is1 risk assessment tools hmg is2 full accreditation statement based hmg is1 itshc security health check deloitte subsequent remediation recipero interface recipero nmpr uk government pnc systems used track mobile devices law enforcement purposes posted publicly public hmg is2 full accreditation statement based actual itshc deloitte case puts auditor reputation line way confidential statement
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Computer security
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udid udid acronym unique device id udid feature apple ios devices unique identifier single device fetched apple servers user tries activate device using icloud setup app id also used itunes detect phone communicate restoring ipsw firmware unique id formatted two ways devices introduced 2007 2018 represented 40-digit lowercase hex code device models introduced 2018 25-digit uppercase hex code written device cover imei retrieved itunes normal mode apple usually uses id assign apple id icloud id device also holds find iphone activation status udid calculated follows verizon iphone 4 devices use
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Operating systems
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pieter van den abeele pieter van den abeele computer programmer founder powerpc-version gentoo linux foundation connected distribution linux computer operating system founded gentoo os x received scholarship apple computer 2004 pieter invited opensolaris pilot program assisted sun microsystems building development eco-system around solaris pieter nominated opensolaris community advisory board managed team developers make gentoo available solaris operating system well pieter co-author gentoo handbook teams managed pieter van den abeele shaped powerpc landscape several firsts gentoo/powerpc first distribution introduce powerpc live cds gentoo also beat apple releasing full 64-bit powerpc userland environment ibm powerpc 970 g5 processor gentoo-based home media communication system based freescale semiconductor powerpc 7447 processor best show award inaugural 2005 freescale technology forum orlando florida pieter also member power.org consortium participates committees workgroups focusing disruptive business plays around power architecture
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Operating systems
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rsa securid rsa securid formerly referred securid mechanism developed security dynamics later rsa security rsa security division emc performing two-factor authentication user network resource rsa securid authentication mechanism consists token — either hardware e.g key fob software soft token — assigned computer user creates authentication code fixed intervals usually 60 seconds using built-in clock card factory-encoded almost random key known seed seed different token loaded corresponding rsa securid server rsa authentication manager formerly ace/server tokens purchased on-demand tokens also available provide tokencode via email sms delivery eliminating need provision token user token hardware designed tamper-resistant deter reverse engineering software implementations algorithm software tokens appeared market public code developed security community allowing user emulate rsa securid software access current rsa securid code original 64-bit rsa securid seed file introduced server later 128-bit rsa securid algorithm published part open source library rsa securid authentication scheme seed record secret key used generate one-time passwords newer versions also feature usb connector allows token used smart card-like device securely storing certificates user authenticating network resource—say dial-in server firewall—needs enter personal identification number number displayed moment rsa securid token though increasingly rare systems using rsa securid disregard pin implementation altogether rely password/rsa securid code combinations server also real-time clock database valid cards associated seed records authenticates user computing number token supposed showing moment time checking user entered older versions securid duress pin may used—an alternate code creates security event log showing user forced enter pin still providing transparent authentication using duress pin would allow one successful authentication token automatically disabled duress pin feature deprecated available currently supported versions rsa securid system adds layer security network difficulty occur authentication server clock becomes sync clock built authentication tokens normal token clock drift accounted automatically server adjusting stored drift value time sync condition result normal hardware token clock drift correcting synchronization authentication manager server clock sync token tokens accomplished several different ways server clock drifted administrator made change system clock tokens either resynchronized one-by-one stored drift values adjusted manually drift done individual tokens bulk using command line utility rsa security pushed forth initiative called ubiquitous authentication partnering device manufacturers ironkey sandisk motorola freescale semiconductor redcannon broadcom blackberry embed securid software everyday devices usb flash drives cell phones reduce cost number objects user must carry token codes easily stolen mutual-authentication exists anything steal password also steal token code significant since principal threat users believe solving technology simplest practical vulnerability password container losing special key device activated smart phone integrated key function vulnerability healed single token container device within preset time span activation consideration presumes loss prevention e.g additional electronic leash body sensor alarm rsa securid tokens offer level protection password replay attacks designed offer protection man middle type attacks used alone attacker manages block authorized user authenticating server next token code valid able log server risk-based analytics rba new feature latest version 8.0 provides significant protection type attack user enabled authenticating agent enabled rba rsa securid prevent man browser mitb based attacks securid authentication server tries prevent password sniffing simultaneous login declining authentication requests two valid credentials presented within given time frame documented unverified post john g. brainard attacker removes user ability authenticate however securid server assume user actually authenticating hence allow attacker authentication attack model system security improved using encryption/authentication mechanisms ssl although soft tokens may convenient critics indicate tamper-resistant property hard tokens unmatched soft token implementations could allow seed record secret keys duplicated user impersonation occur hard tokens hand physically stolen acquired via social engineering end users small form factor makes hard token theft much viable laptop/desktop scanning user typically wait one day reporting device missing giving attacker plenty time breach unprotected system could occur however users userid pin also known risk-based analytics provide additional protection use lost stolen tokens even users userid pin known attackers batteries go flat periodically requiring complicated replacement re-enrollment procedures 2003 rsa securid commanded 70 two-factor authentication market 25 million devices produced date number competitors vasco make similar security tokens mostly based open oath hotp standard study otp published gartner 2010 mentions oath securid competitors network authentication systems opie s/key sometimes generally known otp s/key trademark telcordia technologies formerly bellcore attempt provide something level authentication without requiring hardware token 17 march 2011 rsa announced victims extremely sophisticated cyber attack concerns raised specifically reference securid system saying information could potentially used reduce effectiveness current two-factor authentication implementation however formal form 8-k submission indicated believe breach would material impact financial results breach cost emc parent company rsa 66.3 million taken charge second quarter earnings covered costs investigate attack harden systems monitor transactions corporate customers according emc executive vice president chief financial officer david goulden conference call analysts breach rsa network carried hackers sent phishing emails two targeted small groups employees rsa attached email excel file containing malware rsa employee opened excel file malware exploited vulnerability adobe flash exploit allowed hackers use poison ivy remote administration tool gain control machines access servers rsa network hints breach involved theft rsa database mapping token serial numbers secret token seeds injected make one unique reports rsa executives telling customers ensure protect serial numbers tokens lend credibility hypothesis barring fatal weakness cryptographic implementation token code generation algorithm unlikely since involves simple direct application extensively scrutinized aes-128 block cipher circumstance attacker could mount successful attack without physical possession token token seed records leaked rsa stated release details extent attack give potential attackers information could use figuring attack system 6 june 2011 rsa offered token replacements free security monitoring services 30,000 securid customers following attempted cyber breach defense customer lockheed martin appeared related securid information stolen rsa spite resulting attack one defense customers company chairman art coviello said believe still believe customers protected april 2011 unconfirmed rumors cited l-3 communications attacked result rsa compromise may 2011 information used attack lockheed martin systems however lockheed martin claims due aggressive actions company information security team customer program employee personal data compromised significant tenacious attack department homeland security us defense department offered help determine scope attack
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Computer security
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integrated manufacturing database integrated database system used small large businesses means incorporate manufacturing process updates stores records information view rapid retrieval examples could include capable performing searches particular part may present many different products
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Databases
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microsoft exchange hosted services microsoft exchange hosted services also known frontbridge email filtering system owned microsoft acquired 2005 frontbridge inc. frontbridge technologies began 2000 bigfish communications marina del rey california service sold directly partnership sprint nextel 30 march 2006 microsoft announced new branding new licensing model road map microsoft exchange hosted services ehs formerly known frontbridge technologies inc. microsoft exchange hosted services ehs four new products introduced ehs filtering filter actively help protect inbound outbound e-mail spam viruses phishing scams e-mail policy violations ehs archive message archiving system e-mail instant messages ehs continuity security-enhanced web interface allowed ongoing access e-mail unplanned outages on-premises e-mail environment ehs encryption preserve e-mail confidentiality allowing users send receive encrypted e-mail
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Computer security
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backblaze backblaze data storage provider offers two products founded 2007 backblaze raised total 5.3 million capital profitable backblaze first product computer backup offering allows user back data continuously manually computer idle hourly schedule service makes use aes encryption security uses data compression bandwidth optimization reduce upload download times files need restored delivered form digital download external usb hard drive 8 tb usb flash drive 256 gb september 2015 backblaze launched new product b2 cloud storage infrastructure service iaas targeted software integration though web frontend apis also available directly competes similar services amazon s3 microsoft azure google cloud april 2018 backblaze announced cloud computing partnerships directly connect backblaze data centers partners packet servercentral offering high-performance cloud computing data stored b2 cloud storage transfer fees data uploaded onto backblaze data center sharded 17 data shards plus three parity shards file parity shard bits computed reed–solomon error correction algorithm shards stored 20 storage pods separate cabinet increase resilience power loss entire cabinet backblaze states vault architecture designed 99.999999999 eleven 9s annual durability computer backup backblaze uses combination aes ssl encryption protect user data data stored backblaze storage pods vaults using reed-solomon erasure coding encrypted user private key secured user password username default encryption private keys done server side unlikely protect government subpoena serious data breach users desiring additional security privacy use optional private encryption key pek backblaze b2 cloud storage data stored backblaze storage pods vaults using reed-solomon erasure coding encryption handled entirely user client software used manage stored data making immune government subpoena data breach protecting data transfer ultimate storage backblaze data centers 2009 2011 backblaze released cad drawings computer case used storage servers datacenters commercial off-the-shelf components x64 processors disks motherboards high-density storage servers built lower cost commercial ones february 2013 version 3.0 pod introduced increased storage capacity upgrades march 2014 version 4.0 pod introduced faster simpler less expensive tweaked version 4.5 march 2015 november 2015 version 5.0 storage pod released motherboard cpu sata cards upgraded memory increased 32gb april 2016 version 6.0 storage pod released
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Computer security
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mdadm mdadm linux utility used manage monitor software raid devices used modern gnu/linux distributions place older software raid utilities raidtools2 raidtools mdadm free software maintained copyrighted neil brown suse licensed terms version 2 later gnu general public license name derived md multiple device device nodes administers manages replaced previous utility mdctl original name mirror disk changed functions added name understood short multiple disk device management linux software raid configurations include anything presented linux kernel block device includes whole hard drives example partitions example raid 10 distinct raid 0+1 consists top-level raid 1 mirror composed high-performance raid 0 stripes directly across physical hard disks single-drive failure raid 10 configuration results one lower-level mirrors entering degraded mode top-level stripe performing normally except performance hit single-drive failure raid 0+1 configuration results one lower-level stripes completely failing top-level mirror entering degraded mode two setups preferable depends details application question whether spare disks available spun original standard form names md devices number 0 99 recent kernels support names 2.4.x kernels earlier two options non-partitionable since 2.6.x kernels new type md device introduced partitionable array device names modified changing partitions identified adding partition number thus example since version 2.6.28 linux kernel mainline non-partitionable arrays partitioned partitions referred way partitionable arrays example since version 3.7 linux kernel mainline md supports trim operations underlying solid-state drives ssds linear raid 0 raid 1 raid 5 raid 10 layouts since support md found kernel issue using kernel running specifically present boot loader either e lilo grub legacy although normally present may present grub 2 order circumvent problem filesystem must used either without md support else raid1 latter case system boot treating raid1 device normal filesystem system running remounted md second disk added result catch-up filesystems usually small recent bootloaders possible load md support kernel module initramfs mechanism approach allows filesystem inside raid system without need complex manual configuration besides formats raid volumes metadata linux software raid also supports external metadata formats since version 2.6.27 linux kernel version 3.0 userspace utility allows linux use various firmware- driver-based raid volumes also known fake raid two supported formats external metadata mdmpd daemon used monitoring md multipath devices developed red hat part mdadm package program used monitor multipath raid devices usually started boot time service afterwards running daemon enterprise storage requirements often include desire one way talk single disk drive event failure talk disk drive via one controller system automatically switch another controller keep going called multipath disk access linux kernel implements multipath disk access via software raid stack known md multiple devices driver kernel portion md multipath driver handles routing i/o requests proper device handling failures active path try find path previously failed might working daemon upon startup reads current state md raid arrays saves state waits kernel tell something interesting happened wakes checks see paths multipath device failed starts poll failed path every 15 seconds starts working starts working daemon add path back multipath md device originally part new spare path one using filesystem lists active md devices information mdmpd requires find arrays monitor paths get notification interesting events
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Computer file systems
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gnu mach gnu mach implementation mach microkernel default microkernel gnu hurd gnu mach runs ia-32 machines gnu mach maintained developers gnu project distributed terms gnu general public license gpl early versions hurd developed top cmu mach 3.0 1994 cmu stopped working mach gnu project switched university utah mach 4 kernel known gnu mach derived mach 4 utah stopped development first changelog entry thomas bushnell rather utah researcher 16 december 1996 2002 roland mcgrath branched oskit-mach branch gnu mach 1.2 intending replace device drivers hardware support code oskit release gnu mach 1.3 branch intended become gnu mach 2.0 main line however 2006 oskit-mach developed gnu mach 1.4 released 27 september 2013 eleven years 1.3
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Computer architecture
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time-division multiple access time-division multiple access tdma channel access method shared-medium networks allows several users share frequency channel dividing signal different time slots users transmit rapid succession one using time slot allows multiple stations share transmission medium e.g radio frequency channel using part channel capacity tdma used digital 2g cellular systems global system mobile communications gsm is-136 personal digital cellular pdc iden digital enhanced cordless telecommunications dect standard portable phones tdma first used satellite communication systems western union westar 3 communications satellite 1979 used extensively satellite communications combat-net radio systems passive optical network pon networks upstream traffic premises operator usage dynamic tdma packet mode communication see tdma type time-division multiplexing tdm special point instead one transmitter connected one receiver multiple transmitters case uplink mobile phone base station becomes particularly difficult mobile phone move around vary timing advance required make transmission match gap transmission peers 2g cellular systems notable exception is-95 based tdma gsm d-amps pdc iden phs examples tdma cellular systems gsm combines tdma frequency hopping wideband transmission minimize common types interference gsm system synchronization mobile phones achieved sending timing advance commands base station instructs mobile phone transmit earlier much compensates propagation delay resulting light speed velocity radio waves mobile phone allowed transmit entire time slot guard interval end time slot transmission moves guard period mobile network adjusts timing advance synchronize transmission initial synchronization phone requires even care mobile transmits way actually know offset required reason entire time slot dedicated mobiles attempting contact network known random-access channel rach gsm mobile attempts broadcast beginning time slot received network mobile located next base station time delay succeed however mobile phone less 35 km base station time delay mean mobile broadcast arrives end time slot case mobile instructed broadcast messages starting nearly whole time slot earlier would expected otherwise finally mobile beyond 35 km cell range gsm rach arrive neighbouring time slot ignored feature rather limitations power limits range gsm cell 35 km special extension techniques used changing synchronization uplink downlink base station however limitation overcome although major 3g systems primarily based upon cdma time-division duplexing tdd packet scheduling dynamic tdma packet oriented multiple access schemes available 3g form combined cdma take advantage benefits technologies popular form umts 3g system uses cdma frequency division duplexing fdd instead tdma tdma combined cdma time-division duplexing two standard umts utra itu-t g.hn standard provides high-speed local area networking existing home wiring power lines phone lines coaxial cables based tdma scheme g.hn master device allocates contention-free transmission opportunities cftxop slave devices network one device use cftxop time thus avoiding collisions flexray protocol also wired network used safety-critical communication modern cars uses tdma method data transmission control radio systems tdma usually used alongside frequency-division multiple access fdma frequency division duplex fdd combination referred fdma/tdma/fdd case gsm is-136 example exceptions include dect personal handy-phone system phs micro-cellular systems umts-tdd umts variant china td-scdma use time-division duplexing different time slots allocated base station handsets frequency major advantage tdma radio part mobile needs listen broadcast time slot rest time mobile carry measurements network detecting surrounding transmitters different frequencies allows safe inter frequency handovers something difficult cdma systems supported is-95 supported complex system additions universal mobile telecommunications system umts turn allows co-existence microcell layers macrocell layers cdma comparison supports soft hand-off allows mobile phone communication 6 base stations simultaneously type same-frequency handover incoming packets compared quality best one selected cdma cell breathing characteristic terminal boundary two congested cells unable receive clear signal often negate advantage peak periods disadvantage tdma systems create interference frequency directly connected time slot length buzz sometimes heard tdma phone left next radio speakers another disadvantage dead time time slots limits potential bandwidth tdma channel implemented part difficulty ensuring different terminals transmit exactly times required handsets moving need constantly adjust timings ensure transmission received precisely right time move base station signal take longer arrive also means major tdma systems hard limits cell sizes terms range though practice power levels required receive transmit distances greater supported range would mostly impractical anyway dynamic time-division multiple access dynamic tdma scheduling algorithm dynamically reserves variable number time slots frame variable bit-rate data streams based traffic demand data stream dynamic tdma used
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Internet protocols
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encase encase shared technology within suite digital investigations products guidance software acquired opentext software comes several products designed forensic cyber security security analytics e-discovery use encase traditionally used forensics recover evidence seized hard drives encase allows investigator conduct depth analysis user files collect evidence documents pictures internet history windows registry information company also offers encase training certification data recovered encase used various court systems cases btk killer murder danielle van dam additional encase forensic work documented cases evidence provided casey anthony unabomber mucko wakefield massacre cases encase originally created shawn mccreight founder guidance software 1997 home 1998 encase forensic officially released originally named expert witness windows time gui forensic tools available 2002 encase enterprise released allowing first network enabled digital forensic tool used forensic investigative security matters 2005 encase ediscovery released enabled network abilities encase allow identification collection preservation analysis esi litigation investigative purposes 2007 encase airs automated incident response suite released discontinued evolved encase endpoint security automate scanning documenting remediation abilities encase enterprise also 2007 release encase information assurance encase data audit policy enforcement also effectively integrated encase endpoint security 2008 encase cybersecurity released combined many tools automation previous security functions streamlined workflow incident response 2015 encase endpoint security released evolution endpoint security user friendly web interface well integration many security tools expedite shorten response time attack event 2016 encase enterprise needed face lift distributed agent formerly referred servlet given abilities redesign encase endpoint investigator also 2016 release encase risk manager data risk assessment audit dlp-like services compliance 2017 guidance software acquired opentext company name guidance software longer used encase technology available within number products currently including encase forensic encase endpoint investigator encase ediscovery includes encase legal hold encase endpoint security encase portable guidance software also runs training courses foundations computer forensics several expert series courses include enscripting course automate various functions within encase certification os offered train toward prove knowledge within various fields include ence encase certified examiner encep encase certified ediscovery practitioner cfsr certified forensic security responder encase training team trained 100000 individuals date encase contains tools several areas digital forensic process acquisition analysis reporting software also includes scripting facility called enscript various api interacting evidence encase contains functionality create forensic images suspect media images stored proprietary expert witness file format compressible file format prefixed case data information consists bit-by-bit i.e exact copy media inter-spaced crc hashes every 64k data file format also appends md5 hash entire drive footer encase v7 mobile phone analysis possible addition add-ons available guidance software
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Computer security
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socket fm2+ socket fm2+ fm2b cpu socket used amd desktop steamroller-based godavari apus steamroller-based connect motherboard fm2+ slightly different pin configuration socket fm2 two additional pin sockets socket fm2+ apus compatible socket fm2 motherboards due aforementioned additional pins however socket fm2 apus richland trinity compatible fm2+ socket pcie links capable supporting pcie 2.x data rates addition gfx link capable supporting pcie 3.x data rate available chipsets consult fusion controller hubs fch mobile counterpart socket fp3 µbga906 4 holes fastening heatsink motherboard placed rectangle lateral lengths 48 mm 96 mm amd sockets socket am2 socket am2+ socket am3 socket am3+ socket fm2 cooling solutions therefore interchangeable
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Computer architecture
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comparison operating systems tables provide comparison operating systems computer devices listing general technical information number widely used currently available pc handheld including smartphone tablet computer operating systems article usage share operating systems provides broader general comparison operating systems includes servers mainframes supercomputers large number variety available linux distributions grouped single entry see comparison linux distributions detailed comparison also variety bsd dos operating systems covered comparison bsd operating systems comparison dos operating systems information views operating system see operating system advocacy posix compliant partly compliant systems like freebsd linux macos solaris basic commands standardized note linux systems may vary distribution specific program even 'command called via posix alias function example wanted use dos dir give directory listing one detailed file listing per line could use alias dir='ls -lahf e.g session configuration file
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Operating systems
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weak key cryptography weak key key used specific cipher makes cipher behave undesirable way weak keys usually represent small fraction overall keyspace usually means one generates random key encrypt message weak keys unlikely give rise security problem nevertheless considered desirable cipher weak keys cipher weak keys said flat linear key space virtually rotor-based cipher machines 1925 onwards implementation flaws lead substantial number weak keys created machines problems weak keys others modern block stream ciphers first stream cipher machines also rotor machines problems weak keys traditional rotor machines t52 one stream cipher machine weak key problems british first detected t52 traffic summer autumn 1942 one link sicily libya codenamed sturgeon another aegean sicily codenamed mackerel operators links habit enciphering several messages machine settings producing large numbers depths several mostly incompatible versions t52 t52a t52b differed electrical noise suppression t52c t52d t52e t52a/b t52c cryptologically weak last two advanced devices movement wheels intermittent decision whether advance controlled logic circuits took input data wheels addition number conceptual flaws including subtle ones eliminated one flaw ability reset keystream fixed point led key reuse undisciplined machine operators block cipher des specific keys termed weak keys semi-weak keys keys cause encryption mode des act identically decryption mode des albeit potentially different key operation secret 56-bit key broken 16 subkeys according des key schedule one subkey used sixteen des rounds des weak keys produce sixteen identical subkeys occurs key expressed hexadecimal implementation consider parity bits corresponding keys inverted parity bits may also work weak keys using weak keys outcome permuted choice 1 pc-1 des key schedule leads round keys either zeros ones alternating zero-one patterns since subkeys identical des feistel network encryption function self-inverting despite encrypting giving secure-looking cipher text encrypting twice produces original plaintext des also semi-weak keys produce two different subkeys used eight times algorithm means come pairs k k property e encryption algorithm encrypting message key k six semi-weak key pairs also 48 possibly weak keys produce four distinct subkeys instead 16 found nist publication weak semi-weak keys considered fatal flaws des 2 7.21 × 10 72 quadrillion possible keys des four weak twelve semi-weak tiny fraction possible keyspace users need worry desire check weak semi-weak keys keys generated easy recognize note however currently des longer recommended general use since des keys brute-forced decades since deep crack machine cracking order days computers tend recent solutions vastly cheaper time scale examples progress deep crack article goal 'flat keyspace i.e. keys equally strong always cipher design goal case des sometimes small number weak keys acceptable provided identified identifiable algorithm unknown weak keys inspire much trust two main countermeasures inadvertently using weak key large number weak keys serious flaw cipher design since perhaps large chance randomly generated one weak one compromising security messages encrypted also take longer check randomly generated keys weakness cases tempt shortcuts interest 'efficiency however weak keys much often problem adversary control keys used block cipher used mode operation intended construct secure cryptographic hash function e.g davies–meyer
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Computer security
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jscrambler jscrambler technology company specializing client-side application security solutions web mobile applications javascript application shielding solution enables applications become self-defensive resilient tampering malware injection ip code theft reverse-engineering company also provides webpage monitoring solution enables real-time detection mitigation supply chain attacks dom tampering user interface changes customer hijacking jscrambler solutions used protect web mobile applications number sectors including finance broadcasting advertising media gaming jscrambler started auditmark back 2009 founded 2009 pedro fortuna rui ribeiro company initial focus developing solution fight click-fraud advertising campaigns since traffic audit mechanism javascript dependent name flagship product jscrambler also became name company 2014 jscrambler raised 800,000 seed funding portugal ventures public vc pe firm 2018 jscrambler raised us 2.3 million series round led sonae im co-investment portugal ventures jscrambler also recognized gartner ’ 2018 market guide application shielding 2019 market guide online fraud detection jscrambler products address specific client-side security concerns following dimensions jscrambler ’ products fully compliant main technological frameworks stacks including node.js react angular ionic
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Computer security
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record management services record management services rms procedures vms rsts/e rt-11 high-end rsx-11 operating systems programs may call process files records within files file formats procedures similar virtual storage access method vsam product offered ibm mainframe computers vendors file record management vms rms integral part system software procedures run executive mode rms integrated rt-11 rsts/e available layered product rms supports four record access methods rms supports four record formats
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Operating systems
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hardening computing computing hardening usually process securing system reducing surface vulnerability larger system performs functions principle single-function system secure multipurpose one reducing available ways attack typically includes changing default passwords removal unnecessary software unnecessary usernames logins disabling removal unnecessary services various methods hardening unix linux systems may involve among measures applying patch kernel exec shield pax closing open network ports setting intrusion-detection systems firewalls intrusion-prevention systems also hardening scripts tools like lynis bastille linux jass solaris systems apache/php hardener example deactivate unneeded features configuration files perform various protective measures binary hardening software security technique binary files analyzed modified protect common exploits binary hardening independent compilers involves entire toolchain example one binary hardening technique detect potential buffer overflows substitute safer code advantage manipulating binaries vulnerabilities legacy code fixed automatically without need source code may unavailable obfuscated secondly techniques applied binaries multiple compilers may less secure others binary hardening often involves non-deterministic modification control flow instruction addresses prevent attackers successfully reusing program code perform exploits common hardening techniques
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Computer security
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embedded http server embedded http server component software system implements http protocol examples usage within application might advantages using http perform natural limitations platforms embedded http server runs contribute list non-functional requirements embedded precise embeddable http server requirements every specific project requirements vary significantly example rom ram footprints serious constraint limit choices system designer c++ jvm availability system another constraint frequently performance issue typical embedded systems run multiple simultaneous tasks http server one may configured low priority task
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Web technology
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coda.io coda cloud-based document editor founded shishir mehrotra alex deneui software provides word-processing spreadsheet database functions 2017 coda reported raised 60 million capital
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Distributed computing architecture
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sqlmap sqlmap open source software used detect exploit database vulnerabilities provides options injecting malicious codes penetration testing tool automates process detecting exploiting sql injection flaws providing user interface terminal software run command line available download different operating systems linux distributions windows mac os operating systems addition mapping detecting vulnerabilities software enables access database editing deleting data viewing data tables users passwords backups phone numbers e-mail addresses credit cards confidential sensitive information sqlmap full support multiple dbmss including mysql oracle postgresql microsoft sql server microsoft access ibm db2 sqlite firebird sap maxdb full support injection techniques boolean error stack time union standard use software unix environment follows sqlmap -u http //172.16.0.0/files/file.php id=1 additional values combined help file prompted command sqlmap -h
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Computer security
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wireless internet protocol wireless internet protocols suite wireless protocols wireless application protocol 2.0 wap includes xhtml basic nokia xhtml mobile profile future developments wap open mobile alliance wireless internet protocols able deliver xhtml pages appropriate wireless devices without need http wap proxies using wireless internet protocols web pages rendered differently web browsers handhelds without need two different versions page
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Internet protocols
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direct access file system direct access file system dafs network file system based nfsv4 virtual interface vi data transfer mechanism dafs uses remote direct memory access rdma perform efficient network access data remote files lowers latency reducing number steps needed process transfer remote data file locking cached client side eliminating need access file server subsequent data access dafs initially developed network appliance inc. 85-member industry association named dafs collaborative assembled complete specification draft release v1.0 passed internet engineering task force ietf version 1.0 dafs application programming interface completed 2001 year working version dafs demonstrated using oracle database dafs beta version 1.0 available sourceforge bsd license last updated 2004
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Computer file systems
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daedalian opus game essentially series 36 jigsaw puzzles pentominos must assembled specific shape puzzles start rectangular shapes simple solutions puzzles quickly grow complex odder shapes like rocket ship gun even enlarged versions pentominoes level timed timer started stopped level finished one starts game three pentomino pieces completion early level new piece awarded player final level player given 2x2 square tetromino must complete 8x8 square puzzle completing level player given password access level later time password common english four-letter word guessing common four-letter words players could potentially access levels actually reached playing game name game inspired daedalus mythical character greek legend created labyrinth faithful fan version later coded msx computer system karoshi corporation 2006 game development contest msxdev'06 game ported different platforms pc gp2x
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Computer architecture
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shawn carpenter shawn carpenter american navy veteran whistleblower previously employed sandia national laboratories tracked chinese cyberespionage ring code-named titan rain fbi came national attention story reported september 5 2005 issue time magazine carpenter employee sandia national laboratories investigating security breaches networks however upon tracking several breaches sandia lockheed martin corporation redstone arsenal even nasa dating back 2003 carpenter noticed patterns began appear link attacks single group impressed meticulous voracious incredibly fast manner sometimes completed less 30 minutes hackers operated observations led alert federal government findings titan rain hacking operation first reported august 25 2005 washington post article bradley graham n't mention carpenter graham listed anonymous governmental officials sources informing supervisors breaches told concern sandia computers drop issue employment later terminated carpenter disobeyed management communicated information security breaches first united states army cyber counterintelligence special agents verified information later brought fbi fbi requested senior dac counterintelligence agent known counterintelligence community nickname doc handle carpenter lead operation behalf fbi carpenter confidential informant fbi almost half year sandia discovered actions carpenter reportedly felt betrayed termination viewed actions service country similar previous military service according carpenter termination hearing sandia bruce held sandia chief counterintelligence yelled 're lucky understanding management ... worked would decapitate would least blood office subsequent court case held testified use word decapitate recall using word blood would contest also apologized carpenter sued sandia national laboratories wrongful termination defamation jury awarded almost 4.7 million compensatory punitive damages february 13 2007 jury doubled punitive damages requested carpenter attorneys thad guyer stephani ayers philip davis 13-person new mexico state district court jury determined sandia handling shawn carpenter termination malicious willful reckless wanton fraudulent bad faith juror ed dzienis said sandia interest protecting us certainly n't show way handled shawn ms. alex scott jury forewoman said jurors upset lack documentation process reckless behavior part sandia adequate policies place employees hacking cavalier attitude national security global security carpenter wife dr. jennifer jacobs testified trial dr. jacobs former sandia scientist nuclear engineer west point graduate army reserve major said sandia management questioned loyalty company husband fired dr. jacobs left sandia later appointed white house fellow director united states national security council interview albuquerque journal dr. jacobs stated point us along bad country contractors like sandia corporation behaving way -- impunity citizens n't beginning end country kept coming back expect others sandia corporation private entity manages sandia national laboratories behalf national nuclear security administration department energy federal government united states wholly owned subsidiary for-profit lockheed martin corporation ironic twist carpenter testified trial found hundreds pages detailed schematics sensitive documents labeled lockheed martin proprietary information export controlled regarding mars reconnaissance orbiter stashed foreign server south korea helping fbi investigate stolen lockheed martin information along hundreds network breaches military united states defense contractors sandia officials fired carpenter employed netwitness corporation startup headed amit yoran former director national cyber security division within united states department homeland security march 2007 sandia national laboratories retained three additional attorneys international corporate defense firm baker botts post-trial motions sandia attorneys unsuccessfully argued throw jury verdict reduce judgment zero new trial carpenter attorneys successfully argued motion post-judgment interest sandia ordered pay interest rate 15 per year final judgment 4,742,146.66 plus attorney fees appeals process april 2007 sandia attorneys filed motion appeal jury verdict sandia national laboratories posted 5.8 million supersedeas bond prevent carpenter seizing sandia assets appeals process interest amount almost 60,000 month accumulates sandia pursues appeals according news reports sandia plans appeal new mexico supreme court necessary could take years october 14 2007 albuquerque journal published story analyst sandia settle suit stated sandia dropped appeal verdict according story judgment accumulating 15 percent interest since verdict favor february 2007 piece also related carpenter continues work national security area clients intelligence community federal agencies military
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Computer security
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zoc software zoc popular computer-based terminal emulator telnet software client microsoft windows apple macintosh macos operating systems supports telnet modem ssh 1 2 isdn serial tapi rlogin means communication terminal emulator supports xterm emulation full colors meta-keys local printing vt102 vt220 several types ansi well wyse tvi tn3270 sun cde supports full keyboard remapping scripting rexx languages support named pipes zoc commercial software developed markus schmidt emtec innovative software germany firm produces software various aspects communications via telephone pc isdn like price us 80 free evaluation period 30 days zoc downloaded evaluation emtec several shareware distribution sites emtec produce two associated independent telecommunications programmes use tcp/ip modem isdn etc pyrotrans ftp package including client server pyrobatchftp programmable ftp tool zoc first released os/2 october 1993 v0.95 windows november 1996 v3.02 1997 selected runner-up os/2 e-zine readers choice awards zoc released version 3.11 january 1999 support os/2 discontinued release version 5 mac os x supported version 6
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Operating systems
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beast trojan horse beast windows-based backdoor trojan horse commonly known hacking community remote administration tool rat capable infecting versions windows 95 10 written delphi released first author tataye 2002 became quite popular due unique features used typical client–server model client would operation attacker server would infect victim beast one first trojans feature reverse connection victims established gave attacker complete control infected computer virus would harmless opened opened virus would use code injection method inject applications machine running windows xp removal three files safe mode system restore turned would disinfect system default ports used direct reverse connections 6666 9999 respectively though attacker option changing beast came built-in firewall bypasser ability terminating anti-virus firewall processes also came file binder could used join two files together one executable
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Computer security
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cyber self-defense cybersecurity cyber self-defense refers self-defense cyberattack generally emphasizes active cybersecurity measures computer users sometimes used refer self-defense organizations whole corporate entities entire nations surveillance self-defense variant cyber self-defense largely overlaps active passive cybersecurity measures provide defenders higher levels cybersecurity intrusion detection incident handling remediation capabilities various sectors organizations legally obligated adhere cyber security standards organizations may conduct penetration test via internal team hire third-party organization audit organization systems larger organizations may conduct internal attacker-defender scenarios red team attacking blue team defending defenders namely threat hunters system administrators programmers proactively manage information systems remediate vulnerabilities gather cyber threat intelligence harden operating systems code connected devices networks blue teams may include information physical security personnel employed organization physical security may tested weaknesses employees may target social engineering attacks security audits digital physical systems may audited varying degrees knowledge relevant systems simulate realistic conditions attackers employees frequently trained security practices measures full-knowledge test scenarios known white box tests attacking party knows available information regarding client systems black box tests attacking party provided information regarding client systems gray box tests provide limited information attacking party cybersecurity researcher jeffrey carr compares cyber self-defense martial art one computer network attack surface may shrunk reduce risk exploitation legal theorists policy makers increasingly considering authorizing private sector take active measures hacking-back also known hackbacks contrast active attack measures passive defense measures present reduced risk cyberwarfare legal political economic fallout contemporary topic debate research question 'when cyber-attack threat thereof give rise right self-defense march 2017 tom graves proposed active cyber defense certainty act acdc would enhance computer fraud abuse act cfaa allow individuals private sector use certain tools currently restricted cfaa identify attackers prevent attacks hacking presents chicken egg problem wherein everyone allowed hack anyone everyone would hack everyone skilled resourced would remain brad maryman warns unintended consequences stating view notion legislate accept level undocumented unmonitored cyber actions anyone thinks hacked unfathomable
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Computer security
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pakistan mnp database pakistan mnp database guarantee limited subsidiary four cellular mobile operators pakistan maintains country central number portability clearing house pakistan mobile number portability database guarantee limited pmd incorporated 2005 companies ordinance 1984 launch mnp pakistan pursuant ‘ mobile number portability regulations 2005 ’ s.r.o 763 2005 pakistan first country south asia implement mobile number portability telenor first operator pakistan secure 1 million subscribers mnp
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Databases
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red pitaya hardware red pitaya open-source hardware project intended alternative many expensive laboratory measurement control instruments core selling point inclusion 2x 125ms/s rf input 2x 125ms/s rf outputs 50 mhz analogue bandwidth 14 bit analog-to-digital digital-to-analog converters software includes oscilloscope spectrum analyzer signal generator lcr meter lcr add costs additional 400 euros 50 mhz 2x2 mimo pid controller re-programmed become devices io ports connected common field-programmable gate array fpga also auxiliary adc 250ks/s digital io three usb 2.0 ports wifi ethernet connector internally uses linux operating system mass storage device operating system micro-sd card due wide bandwidth adc dac red pitaya used software defined radio receiver transmitter radio frequency applications hamlab fully featured sdr hf tranceiver output power 10 w based red pitaya board expected released amateur radio market october 2016 although software including hdl source code project made freely available device fully open source hardware project device electrical schematics made openly available
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Computer architecture
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amazon s3 amazon s3 amazon simple storage service service offered amazon web services aws provides object storage web service interface amazon s3 uses scalable storage infrastructure amazon.com uses run global e-commerce network amazon s3 employed store type object allows uses like storage internet applications backup recovery disaster recovery data archives data lakes analytics hybrid cloud storage service-level agreement amazon s3 guarantees 99.9 monthly uptime works less 43 minutes downtime per month aws launched amazon s3 united states march 14 2006 europe november 2007 although amazon web services aws publicly provide details s3 technical design amazon s3 manages data object storage architecture aims provide scalability high availability low latency 99.999999999 durability 99.95 99.99 availability though service-level agreement durability basic storage units amazon s3 objects organized buckets object identified unique user-assigned key buckets managed using either console provided amazon s3 programmatically using aws sdk amazon s3 rest application programming interface api objects managed using aws sdk amazon s3 rest api five terabytes size two kilobytes metadata additionally objects downloaded using http get interface bittorrent protocol requests authorized using access control list associated object bucket support versioning disabled default note since buckets typically size entire file system mount systems access control scheme coarse-grained i.e unique access controls associated individual files bucket names keys chosen objects addressable using http urls amazon s3 used replace significant existing static web-hosting infrastructure http client accessible objects amazon aws authentication mechanism allows bucket owner create authenticated url valid specified amount time every item bucket also served bittorrent feed amazon s3 store act seed host torrent bittorrent client retrieve file drastically reduce bandwidth cost download popular objects use bittorrent reduce bandwidth aws provide native bandwidth limiting users access automated cost control lead users free-tier amazon s3 small hobby users amassing dramatic bills aws representatives stated bandwidth limiting feature design table 2006 2010 2011 feature longer development bucket configured save http log information sibling bucket used data mining operations various user mode file system fuse -based file systems unix-like operating systems linux etc used mount s3 bucket file system s3ql semantics amazon s3 file system posix file system file system may behave entirely expected amazon s3 provides option host static html websites index document support error document support support added result user requests dating least 2006 example suppose amazon s3 configured cname records host codice_5 past visitor url would find xml-formatted list objects instead general landing page e.g. index.html accommodate casual visitors however websites hosted s3 may designate default page display another page display event partially invalid url 404 error amazon s3 allows users enable disable logging enabled logs stored amazon s3 buckets analyzed logs contain useful information logs analyzed managed using third-party tools like s3stat cloudlytics qloudstat awstats splunk amazon s3 provides api developers aws console provides tools managing uploading files capable managing large buckets editing files third-party websites like s3edit.com software like cloudberry explorer forklift webdrive capability edit files amazon s3 amazon s3 offers four different storage classes offer different levels durability availability performance requirements broad adoption amazon s3 related tooling given rise competing services based s3 api services use standard programming interface however differentiated underlying technologies supporting business models cloud storage standard like electrical networking standards enables competing service providers design services clients using different parts different ways yet still communicate provide following benefits examples competing amazon s3-compliant storage implementations amazon web services introduced amazons3 2006 amazon s3 reported store 2 trillion objects 10 billion objects october 2007 14 billion objects january 2008 29 billion objects october 2008 52 billion objects march 2009 64 billion objects august 2009 102 billion objects march 2010
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Computer file systems
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zmap software zmap free open-source security scanner developed faster alternative nmap zmap designed information security research used white hat black hat purposes tool able discover vulnerabilities impact detect affected iot devices using one gigabit per second network bandwidth zmap scan entire ipv4 address space hour single port zmap iterates techniques utilized predecessor nmap altering scanning method key areas nmap sends individual signals ip address waits reply replies return nmap compiles database keep track responses process slows scanning process contrast zmap uses cyclic multiplicative groups allows zmap scan space roughly 1,300 times faster nmap zmap software takes every number 1 2-1 creates iterative formula ensures possible 32-bit numbers visited pseudorandom order building initial list numbers every ip address takes upfront time fraction required aggregate list every sent received probe process ensures zmap starts sending probes different ips accidental denial service could occur abundance transmissions would converge one subnet time zmap also speeds scanning process sending probe every ip address default whereas nmap resends probe detects connection delay fails get reply results 2 ip addresses missed typical scan processing billions ip address potential iot devices targeted cyberattackers 2 acceptable tolerance zmap used vulnerability detection exploitation application used port 443 scans estimate power outages hurricane sandy 2013 one developers zmap zakir durumeric used software determine computer online state vulnerabilities operating system services zmap also used detect vulnerabilities universal plug play devices search weak public keys https website logs
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Computer security
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extremedb extremedb high performance low-latency acid-compliant embedded database management system using in-memory database system imds architecture designed linked c/c++ based programs works windows linux real-time embedded operating systems building core imds several editions supporting high availability database clustering hybrid in-memory disk-based data storage columnar layout time series data financial market data specialized abilities mcobject introduced extremedb 2001 targeting embedded systems running resource-constrained environments i.e limited random-access memory relatively low-powered central processing units extremedb characteristics appealing market include small code size approximately 150 kb native c language application programming interface available source code high degree portability support varied processors operating systems used embedded systems early deployments customers included integration digital tv set-top boxes manufacturing industrial control systems telecom/networking devices extremedb emerged manage industry analysts mcobject portray significant growth amount data managed devices company claims extremedb first embedded database management system dbms developed specifically environments later editions targeted high performance non-embedded software market including capital markets applications algorithmic trading order matching engines real-time caching web-based applications including social networks e-commerce features added support focus include sql odbc jdbc interfaces 64-bit support multiversion concurrency control mvcc transaction management increasingly popular term “ internet things ” especially since 2009 encompasses real-time embedded systems extremedb supports following features across product family extremedb supports multiple concurrent users offering acid-compliant transactions defined jim gray using either two transaction managers multiple-reader single writer mursiw locking mechanism multiversion concurrency control mvcc transaction manager optimistic non-locking model extremedb work virtually c language data types including complex types including structures arrays vectors blobs unicode supported extremedb high availability edition supports synchronous 2-safe asynchronous 1-safe database replication automatic failover extremedb cluster edition provides shared-nothing database clustering extremedb also supports distributed query processing database partitioned horizontally dbms distributes query processing across multiple servers cpus and/or cpu cores extremedb supports heterogeneous client platforms e.g mix windows linux rtoss clustering high availability features single partitioned database include shards running mix hardware os platforms extremedb fusion edition provides option persistent storage disk flash specific tables via database schema notation extremedb transaction logging edition keeps record changes made database uses log provide recovery event device system failure edition includes extremedb data relay technology replicates selected changes external systems enterprise applications database systems extremesql edition provides sql odbc support extremedb version 4 level 4 jdbc driver extremedb kernel mode edition deploys database system within operating system kernel provide database functions kernel-based applications logic extremedb financial edition provides features managing market data tick data applications algorithmic trading order matching “ sequences ” data type supports columnar data layout enables extremedb offer benefits column-oriented database handling time series data financial edition also provides library vector-based statistical functions analyze data sequences performance monitor mcobject published reports benchmark tests employing extremedb main-memory vs. ram-disk databases linux-based benchmark examined imds performance versus traditional on-disk dbms deployed ram disk identical application tasks benchmark ’ stated goal test thesis imds streamlined architecture delivers performance benefit beyond provided memory-based storage another benchmark terabyte-plus in-memory database system imds benchmark documented imds scalability performance size range large enterprise application versus embedded systems databases test engineers created 1.17 terabyte 15.54 billion row database extremedb 160-core sgi altix 4700 system running suse linux enterprise server 9 november 2012 marketing report published dell servers mellanox infiniband late 2014 two additional audited benchmark reports focused extremedb financial edition october 29 report assessed mcobject ’ dbms ibm power8 hardware november 18 report documented use cloud computing 2016. another report measured extremedb financial edition
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Databases
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minerva qdos reimplementation written laurence reeves england minerva reimplementation sinclair qdos built-in operating system sinclair ql line personal computers minerva incorporated many bug fixes enhancements qdos superbasic programming language later versions also provided ability multi-task several instances superbasic interpreter something supported qdos minerva distributed rom chip daughterboard replaced ql original rom chips minerva mk ii daughterboard also produced also incorporated i²c interface non-volatile real-time clock version 1.89 minerva source code licensed gnu general public license reimplementations qdos include sms2 smsq/e
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Operating systems
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livermore time sharing system livermore time sharing system ltss supercomputer operating system originally developed lawrence livermore laboratories control data corporation 6600 7600 series supercomputers ltss resulted cray time sharing system network livermore timesharing system nltss
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Operating systems
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semantic similarity semantic similarity metric defined set documents terms idea distance based likeness meaning semantic content opposed similarity estimated regarding syntactical representation e.g string format mathematical tools used estimate strength semantic relationship units language concepts instances numerical description obtained according comparison information supporting meaning describing nature term semantic similarity often confused semantic relatedness semantic relatedness includes relation two terms semantic similarity includes relations example car similar bus also related road driving computationally semantic similarity estimated defining topological similarity using ontologies define distance terms/concepts example naive metric comparison concepts ordered partially ordered set represented nodes directed acyclic graph e.g. taxonomy would shortest-path linking two concept nodes based text analyses semantic relatedness units language e.g. words sentences also estimated using statistical means vector space model correlate words textual contexts suitable text corpus concept semantic similarity specific semantic relatedness latter includes concepts antonymy meronymy similarity however much literature uses terms interchangeably along terms like semantic distance essence semantic similarity semantic distance semantic relatedness mean much term term b answer question usually number -1 1 0 1 1 signifies extremely high similarity intuitive way visualizing semantic similarity terms grouping together terms closely related spacing wider apart ones distantly related also common practice mind maps concept maps sometimes subconscious direct way visualizing semantic similarity two linguistic items seen semantic folding approach approach linguistic item term text represented generating pixel active semantic features e.g 128 x 128 grid allows direct visual comparison semantics two items comparing image representations respective feature sets semantic similarity measures applied developed biomedical ontologies mainly used compare genes proteins based similarity functions rather sequence similarity also extended bioentities diseases comparisons done using tools freely available web similarity also applied find similar geographic features feature types several metrics use wordnet manually constructed lexical database english words despite advantages human supervision constructing database since words automatically learned database measure relatedness multi-word term non-incremental vocabulary natural language processing nlp field computer science linguistics sentiment analysis natural language understanding machine translation automatically translate text one human language another major areas used example knowing one information resource internet often immediate interest find similar resources semantic web provides semantic extensions find similar data content arbitrary descriptors essentially two types approaches calculate topological similarity ontological concepts measures calculate similarity ontological instances examples statistical similarity approaches learned data predefined similarity learning often outperform predefined similarity measures broadly speaking approaches build statistical model documents use estimate similarity researchers collected datasets similarity judgements pairs words used evaluate cognitive plausibility computational measures golden standard today old 65 word list humans judged word similarity list datasets overview state art see https //www.aclweb.org/
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Computational linguistics
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scicos scicos graphical dynamical system modeler simulator users create block diagrams model simulate dynamics hybrid dynamical systems continuous discrete time compile models executable code applications include signal processing systems control queuing systems study physical biological systems scilab includes toolbox called xcos based scicos scicos developed distributed scientific software package scicoslab scicos 4.4.1 released april 2011 book modeling simulation scilab/scicos scicoslab 4.4 campbell chancelier nikoukhah provides overview software
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Programming language topics
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radrails radrails rapid application development ide ruby rails framework goal radrails provide ruby rails developers everything need develop manage test deploy applications features include source control code assist refactoring debugging webrick servers generator wizards syntax highlighting data tools much radrails ide built eclipse rcp includes rdt subclipse plug-in radrails tools also available eclipse +plug-ins eclipsecon 2006 radrails community award best open-source eclipse-based tool radrails started kyle shank marc baumbach matt kent september 2005 time three developers worked co-ops rochester institute technology ibm rational raleigh nc development continued 2006 including contributions andy gianfagna ryan lowe joined team mid-2006 deploy maintain automated build system project november 2006 kyle shank matt kent began working idea startup company would eventually become persai march 2007 kyle matt devoting spare time persai little time left maintain radrails kyle met aptana founder paul colton eclipsecon 2007 became clear handing project would best interests radrails community march 8 2007 aptana took project renamed aptana radrails although radrails still open source project work done aptana employee christopher williams lead developer rdt project radrails built upon radrails 1.0 released open source license march 13 2008 plug-in aptana studio eclipse-based ide web ajax development run either standalone within eclipse may 2008 book aptana radrails ide rails development written javier ramírez published packt publishing book covers features community edition 1.0
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Databases
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toric code toric code topological quantum error correcting code example stabilizer code defined two-dimensional spin lattice simplest well studied quantum double models also simplest example topological order— z topological order first studied context z spin liquid 1991 toric code also considered z lattice gauge theory particular limit introduced alexei kitaev toric code gets name periodic boundary conditions giving shape torus conditions give model translational invariance useful analytic study however experimental realization requires open boundary conditions allowing system embedded 2d surface resulting code typically known planar code identical behaviour toric code cases toric code defined two-dimensional lattice usually chosen square lattice spin-½ degree freedom located edge chosen periodic stabilizer operators defined spins around vertex formula_1 plaquette face formula_2 lattice follows formula_3 use formula_4 denote edges touching vertex formula_1 formula_6 denote edges surrounding plaquette formula_2 stabilizer space code stabilizers act trivially hence formula_8 state formula_9 toric code space four-dimensional used store two qubits quantum information proven considering number independent stabilizer operators occurrence errors move state stabilizer space resulting vertices plaquettes condition hold positions violations syndrome code used error correction unique nature topological codes toric code stabilizer violations interpreted quasiparticles specifically code state formula_10 formula_11 quasiparticle known formula_12 anyon said exist vertex formula_1 similarly violations formula_14 associated called formula_15 anyons plaquettes stabilizer space therefore corresponds anyonic vacuum single spin errors cause pairs anyons created transported around lattice errors create anyon pair move anyons one imagine path connecting two composed links acted upon anyons meet annihilated path describes loop loop topologically trivial effect stored information annihilation anyons case corrects errors involved creation transport however loop topologically non-trivial though re-annihilation anyons returns state stabilizer space also implements logical operation stored information errors case therefore corrected consolidated consider noise model bit phase errors occur independently spin probability p p low create sparsely distributed pairs anyons moved far point creation correction achieved identifying pairs anyons created equivalence class re-annihilating remove errors p increases however becomes ambiguous anyons may paired without risking formation topologically non-trivial loops gives threshold probability error correction almost certainly succeed mapping random-bond ising model critical probability found around 11 error models may also considered thresholds found cases studied far code found saturate hashing bound error models biased errors bit errors occur often phase errors vice versa lattices square lattice must used achieve optimal thresholds thresholds upper limits useless unless efficient algorithms found achieve well-used algorithm minimum weight perfect matching applied noise model independent bit flip errors threshold around 10.5 achieved falls little short 11 maximum however matching work well correlations bit phase errors depolarizing noise means perform quantum computation logical information stored within toric code considered properties code providing fault-tolerance shown extending stabilizer space using 'holes vertices plaquettes stabilizers enforced allows many qubits encoded code however universal set unitary gates fault-tolerantly implemented unitary operations additional techniques required achieve quantum computing example universal quantum computing achieved preparing magic states via encoded quantum stubs called tidbits used teleport required additional gates replaced qubit furthermore preparation magic states must fault tolerant achieved magic state distillation noisy magic states measurement based scheme quantum computation based upon principle found whose error threshold highest known two-dimensional architecture since stabilizer operators toric code quasilocal acting spins located near two-dimensional lattice unrealistic define following hamiltonian formula_16 ground state space hamiltonian stabilizer space code excited states correspond anyons energy proportional number local errors therefore energetically suppressed gap shown stable local perturbations however dynamic effects perturbations still cause problems code gap also gives code certain resilience thermal errors allowing correctable almost surely certain critical time time increases formula_17 since arbitrary increases coupling unrealistic protection given hamiltonian still limits means make toric code planar code fully self-correcting quantum memory often considered self-correction means hamiltonian naturally suppress errors indefinitely leading lifetime diverges thermodynamic limit found possible toric code long range interactions present anyons proposals made realization lab another approach generalization model higher dimensions self-correction possible 4d quasi-local interactions mentioned called formula_12 formula_15 quasiparticles associated vertices plaquettes model respectively quasiparticles described anyons due non-trivial effect braiding specifically though species anyons bosonic respect braiding two formula_12 formula_15 effect full monodromy formula_12 formula_15 yield phase formula_24 result consistent either bosonic fermionic statistics hence anyonic anyonic mutual statistics quasiparticles demonstrate logical operations performed topologically non-trivial loops consider creation pair formula_12 anyons followed transport one around topologically nontrivial loop shown torus blue figure pair reannhilated state returned stabilizer space loop implements logical operation one stored qubits formula_15 anyons similarly moved red loop logical operation also result phase formula_24 resulting braiding anyons shows operations commute rather anticommute may therefore interpreted logical formula_28 formula_29 pauli operators one stored qubits corresponding logical pauli qubit correspond formula_15 anyon following blue loop formula_12 anyon following red braiding occurs formula_12 formula_15 pass parallel paths phase formula_24 therefore arise corresponding logical operations commute expected since form operations acting different qubits due fact formula_12 formula_15 anyons created pairs clear see quasiparticles antiparticles composite particle composed two formula_12 anyons therefore equivalent vacuum since vacuum yield pair pair annihilate vacuum accordingly composites bosonic statistics since braiding always completely trivial composite two formula_15 anyons similarly equivalent vacuum creation composites known fusion anyons results written terms fusion rules case take form formula_39 formula_40 denotes vacuum composite formula_12 formula_15 trivial therefore constitutes another quasiparticle model sometimes denoted formula_43 fusion rule formula_44 braiding statistics anyons see since single exchange two formula_43 involve full monodromy constituent formula_12 formula_15 phase formula_24 result implies fermionic self-statistics formula_43 use torus required form error correcting code surfaces may also used topological properties determining degeneracy stabilizer space general quantum error correcting codes defined two-dimensional spin lattices according principles known surface codes also possible define similar codes using higher-dimensional spins quantum double models string-net models allow greater richness behaviour anyons may used advanced quantum computation error correction proposals include models abelian anyons also non-abelian statistics explicit demonstration properties toric code state based approaches rather attempting realize hamiltonian simply prepare code stabilizer space using technique experiments able demonstrate creation transport statistics anyons recent experiments also able demonstrate error correction properties code realizations toric code generalizations hamiltonian much progress made using josephson junctions theory hamiltonians may implemented developed wide class topological codes experiment also performed realizing toric code hamiltonian small lattice demonstrating quantum memory provided degenerate ground state theoretical experimental works towards realizations based cold atoms toolkit methods may used realize topological codes optical lattices explored
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Computer architecture
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type-length-value within data communication protocols tlv type-length-value tag-length-value encoding scheme used optional information element certain protocol type length fixed size typically 1-4 bytes value field variable size fields used follows advantages using tlv representation data system solution imagine message make telephone call first version system might use two message elements command phonenumbertocall codice_1 codice_2 codice_3 integer constants 4 8 lengths value fields respectively later version 2 new field containing calling number could added version 1 system received message version 2 system would first read codice_1 element read element type codice_5 version 1 system understand codice_5 length field read i.e 14 system skips forward 14 bytes read understands message parsing carries example usage link layer discovery protocol allows sending organizational-specific information tlv element within lldp packets another example rr protocol used gsm cell phones defined 3gpp 04.18 rr protocol message defined sequence information elements many protocols use tlvs cops is-is radius core tcp/ip protocols particularly ip tcp udp use predefined static fields common tcp/ip-based protocols http ftp smtp pop3 sip use text-based field value pairs formatted according rfc 2822 asn.1 specifies several tlv-based encoding rules ber der well non-tlv based ones per xer csn.1 describes encoding rules using non-tlv semantics recently xml used implement messaging different nodes network messages typically prefixed line-based text commands beep
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Internet protocols
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cure53 cure53 german cybersecurity firm company found dr.ing mario heidrich client side security researcher report firm south korean security app smart sheriff described security holes catastrophic south korean government ordered app shut
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Computer security
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comparison c sharp visual basic .net c visual basic .net two primary languages used program .net framework c vb.net syntactically different languages different histories name suggests c syntax based core c programming language originally developed dennis ritchie bell labs 1970s java c++ two programming languages whose syntax also based c syntax share common look feel see comparison java c sharp topic basic roots go back dartmouth college basic beginner all-purpose symbolic instruction code developed 60 method overcome difficulties using assembly language written processor specific and/or brand name specific main frames hardware may recall programming hardware dependent design marketing reasons preserve logical composition programming transcend hardware microsoft claim fame operating system free consumers hardware specific devices encapsulating task within operating system code became portable due compiler fact visual basic .net c use clr common language runtime today microsoft hp interested creating iso standard language original goal however hp dropped support iso computer language never materialized international standard vb.net roots basic language '60s name acronym beginner all-purpose symbolic instruction code beginning basic used college community basic language first exposure computer programming acronym represented language accurately '70s language picked microcomputer manufacturers era used simple rom embedded programming language well quasi operating system input/output control early '80s language picked microsoft expanded significantly beyond original intent visual basic language/platform sold throughout 1990s rapid application development rad tool windows programming competed directly rad tools 1990s powerbuilder even though visual basic successful development platform discontinued 6th version vb6 microsoft introduced .net framework related visual studio development platform early 2000s time current c++ vb6 languages used microsoft basis two new programming languages new integrated development environment ide languages named c vb.net february 2017 microsoft communicated intent end co-evolution strategy two languages existed since 2010 allow two languages evolve independently c dominant microsoft-based development language developers notice vb 15 first appearing visual studio 2017 lacks certain language capabilities contained new c 7.3 though c vb.net syntactically different differences mostly end microsoft developed languages part .net framework development platform developed managed supported language development team microsoft compile intermediate language il runs .net framework runtime libraries although differences programming constructs discussed differences primarily syntactic assuming one avoids visual basic compatibility libraries provided microsoft aid conversion vb6 almost every command vb equivalent command c vice versa lastly languages reference base classes .net framework extend functionality result exceptions program written either language run simple syntax converter translate many open source commercially available products task fundamental differences languages found implementation interfaces declaration raising handling events although languages high-level programming languages vb.net maintains slightly higher level abstraction respects one main goals .net multi-language support intent design various microsoft languages level access os features able expose level power usability simplify calling module one language written another language implementation .net programming languages share runtime engine uniform abstract syntax tree common intermediate language additionally .net languages access platform features including garbage collection cross language inheritance exception handling debugging allows output binary produced .net programming language visual studio provides minor differences development environment c vb.net subsequent release visual studio differences development environments languages reduced instance early versions visual studio poor support intellisense c compared visual basic .net offer background compilation c currently main differences development environments additional features visual basic .net originated vb6 including background compilation feature visual studio ide whereby code compiled written programmer purpose identifying compilation errors without requiring solution built feature available visual basic since .net 1.1 present early versions visual studio visual basic .net however background compilation relatively new concept visual c available service pack 1 visual studio 2008 standard edition distinct disadvantage c error list panel update solution rebuilt refactoring large projects c made difficult need frequently rebuild solution order highlight compilation errors case visual basic error list panel synchronized background compiler background compilation less demanding system resources results faster build cycles particular advantage large projects significantly reduce time required start debugging ide bulk differences c vb.net technical perspective syntactic sugar features languages things easier one language another many differences two languages actually centered around ide although default codice_53 backward compatibility reasons recommended microsoft widely considered good practice turn codice_53 due fact increases application performance reduces possibility naming errors programming mistakes visual basic .net terminates block code codice_59 statements codice_60 statements loop familiar programmers experience using t-sql c braces codice_61 used delimit blocks familiar programmers experience widely deployed languages c++ java additionally c block consists single statement braces may omitted c case sensitive visual basic .net thus c possible two variables apparent name example codice_62 codice_63 visual studio correct make uniform case variables typed vb.net cases however case sensitivity useful c programmers typically capitalize type member names leave field variable names lowercase allows example fairly natural naming method arguments codice_64 however cause problems converting c code case-insensitive language visual basic unaccustomed reading case sensitive language visual basic case sensitive means combinations upper lower case letters keywords acceptable visual studio automatically converts visual basic keywords default capitalised forms e.g public c case sensitive c keywords lower cases visual basic c share keywords difference default visual basic keywords capitalised versions c keywords e.g codice_65 vs codice_66 codice_18 vs codice_68 keywords different versions visual basic c c keywords codice_80 represent different things applied methods opposed applied class definitions vb.net hand uses different keywords different contexts c vb.net high adoption rates active developer communities microsoft fully supports communities .net framework developers widely use vb.net c primary languages however c community activity internet books available c may indicate either adoption c users need help examples community industry adoption include c++/cli replacement managed extensions c++ adoption rate c vb.net significant following c++/cli syntactically stylistically culturally closest c however c++/cli stays closer c++ roots c c++/cli directly supports pointers destructors unsafe program concepts supported limited languages allows direct use .net code standard c++ code c++/cli used porting native/legacy c++ applications .net framework cases programmer wants take control code control comes significant cost ease use readability many automated tools come visual studio reduced functionality interacting c++ code reflection provide much information code c vb.net j runs distant fourth terms adoption j language primarily designed ease transition java applications .net framework allows developers leave much java j++ code unchanged still running .net framework thus allowing migrate small pieces another .net language c individually j receive level updates languages level community support example visual studio 2005 team system supports automatic generation unit tests c vb.net c++ excludes j j discontinued included visual studio 2008 newer versions since existing j feature set largely meets customer needs usage j declining .net languages compile common intermediate language cil contains rich metadata functionally logically equivalent original .net language code reasons possible code directly cil rarely done equivalency cil .net language code permits tools .net reflector transform .net assembly source code nearly identical original source code obfuscators often used guard operate directly modifying cil assembly order make difficult impossible de-compile higher level .net language
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Programming language topics
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high-tech bridge high-tech bridge sa web security company based geneva switzerland develops machine learning artificial intelligence technologies application security via ast platform immuniweb ai started december 2007 vendor-neutral penetration testing boutique high-tech bridge named industry leader best service provider among ethical hacking penetration testing companies frost sullivan market research 2012 high-tech bridge founded ilia kolochenko swiss application security expert sc media thought leader forbes technology council member contributing editor sc magazine uk dark reading idg cso online november 2013 international telecommunication union high-tech bridge agreed use immuniweb part itu toolset ensuring websites itu member states secure july 2015 high-tech bridge pricewaterhousecoopers switzerland announced strategic partnership based around immuniweb web penetration testing continuous monitoring vulnerability assessment capabilities partnership afterward expanded pwc global offices including pwc singapore high-tech bridge security research team released 500 security advisories affecting various software issues identified products many well-known vendors sony mcafee novell addition many web vulnerabilities affecting popular open source commercial web applications oscommerce zen cart microsoft sharepoint sugarcrm others high-tech bridge security research lab registered cve cwe compatible mitre high-tech bridge one 24 organizations globally first switzerland able achieve cwe certification company listed among 81 organizations august 2013 include cve identifiers security advisories high-tech bridge launched ssl/tls configuration testing tool october 2015 tool validates email web tls ssl server configuration nist guidelines checks pci dss compliance cited articles covering talktalk data breach discovery vulnerabilities yahoo sites high-tech bridge widely reported leading t-shirt gate affair changes yahoo bug bounty program high-tech bridge identified reported four xss vulnerabilities yahoo domains company awarded two gift vouchers value 25 sparse reward offered security researchers identifying vulnerabilities yahoo criticized sparking came called t-shirt-gate campaign yahoo sending t-shirts thanks discovering vulnerabilities high-tech bridge discovery vulnerabilities subsequent criticism yahoo reward program led yahoo rolling new vulnerability reporting policy offers 150 15,000 reported issues based pre-established criteria december 2013 high-tech bridge research privacy popular social networks email services cited class action lawsuit allegedly violating members privacy scanning private messages sent social network october 2014 high-tech bridge discovered remote code execution vulnerabilities php december 2014 high-tech bridge identified ransomweb attack development ransomware attacks hackers started taking webs servers encrypting data demanding payment unlock files april 2014 discovery sophisticated drive-by download attacks revealed drive-by download attacks used target specific website visitors authentication compromised web resource december 2015 high-tech bridge tested popular free email service providers ssl/tls email encryption hushmail previously considered one secure email providers received failing f grade company updated ssl configuration received score b+ march 2015 immuniweb recognized frost sullivan 2015 market insight 'the complete hybrid offering available april 2016 high-tech bridge selected red herring europe 2016 winner sc media reboot 2016 named immuniweb industry innovator analysis testing category april 2017 frost sullivan research machine learning application security testing ast recognized high-tech bridge innovative player ast marketplace outperforming hpe ibm security may 2017 gartner named high-tech bridge garter cool vendor cool vendors security midsize enterprises 2017 adam hils june 2017 high-tech bridge selected sc awards europe 2017 winner best emerging technology category june 2018 immuniweb named winner “ best usage machine learning ai ” category sc awards europe 2018 outperforming six finalists including ibm watson cybersecurity high-tech bridge member number security-related organizations including
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Computer security
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ticket punch ticket punch control nippers hand tool permanently marking admission tickets similar items paper card stock makes perforation corresponding chad ticket punch resembles hole punch differing ticket punch longer jaw reach option distinctive die shape ticket punch resembles needle punch makes distinctive pattern item punched differs makes chad ticket punches widely used mark railway passenger tickets particularly important ticket punched ticket punches also widely used orienteering replaced needle punches see control point orienteering ticket punches also decorative uses involving perforations chads available die shapes include many geometric shapes silhouettes objects animals die shapes company logos proprietary images manufactured special arrangement used punch decorative holes margins pieces paper make small confetti punched tickets issued best buses mumbai till 2011 replaced electronic ticketing systems older tickets reportedly used artwork well games
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Computer security
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machine identification code machine identification code mic also known printer steganography yellow dots tracking dots secret dots digital watermark certain color laser printers copiers leave every single printed page allowing identification device document printed giving clues originator developed xerox canon mid-1980s existence became public 2004 2018 scientists developed privacy software anonymize prints order support whistleblowers publishing work mid-1980s xerox pioneered encoding mechanism unique number represented tiny dots spread entire print area xerox developed machine identification code assuage fears color copiers could used counterfeit bills received u.s. patent 5515451 describing use yellow dots identify source copied printed document october 2004 consumers first heard hidden feature used dutch authorities track counterfeiters used canon color laser printer november 2004 pc world broke news machine identification code used decades printers allowing law enforcement identify track counterfeiters central bank counterfeit deterrence group cbcdg denied developed feature 2005 civil rights group electronic frontier foundation eff encouraged public send sample printouts subsequently decoded pattern pattern demonstrated wide range printers different manufacturers models eff stated 2015 documents previously received foia suggested major manufacturers color laser printers entered secret agreement governments ensure output printers forensically traceable 2007 european parliament asked question invasion privacy pattern consists dot-matrix spread yellow dots barely seen naked eye dots diameter tenth millimeter 0.004 spacing one millimeter 0.039 arrangement encodes serial number device date time printing repeated several times across printing area case errors example code consists 8 × 16 dots square hexagonal pattern spreads surface appears sheet size din-a4 paper 150 times thus analyzed even fragments excerpts available printers arrange yellow dots seemingly random point clouds according chaos computer club 2005 color printers leave code matrix 32 × 16 dots thus store 64 bytes data 64×8 xerox one manufacturers draw attention marked pages stating product description digital color printing system equipped anti-counterfeit identification banknote recognition system according requirements numerous governments copy shall marked label necessary allows identification printing system created code visible normal conditions 2018 scientists tu dresden analyzed patterns 106 printer models 18 manufacturers found four different encoding schemes machine identification code made visible printing copying page subsequently scanning small section high-resolution scanner yellow color channel enhanced image processing program make dots mic clearly visible good lighting conditions magnifying glass may enough see pattern uv-light yellow dots clearly recognizable using steganographic process high-quality copies original e.g bank note blue light made identifiable using process even shredded prints restored 2011 shredder challenge initiated darpa solved team called shreds belong u.s. consisting otavio good two colleagues copies printouts documents confidential personal information example health care information account statements tax declaration balance sheets traced owner printer creation date documents revealed traceability unknown many users inaccessible manufacturers publicize code produces patterns unclear data may unintentionally passed copy printout particular mentions technique support materials affected printers exceptions see 2005 electronic frontier foundation eff sought decoding method made available python script analysis 2018 scientists tu dresden developed published tool extract analyze steganographic codes given color printer subsequently anonymize prints printer anonymization works printing additional yellow dots top machine identification code scientists made software available order support whistleblowers efforts publicize grievances methods identification easily recognizable yellow dots example modulation laser intensity variation shades grey texts already feasible unknown whether manufacturers using techniques
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Computer security
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edholm law edholm law named phil edholm says three categories communication namely wireless mobile nomadic wireless without mobility wired network fixed lockstep converge edholm law also holds data rates telecommunications categories increase similar exponential curves slower rates trailing faster ones predictable time lag soon even slower communications channels like cellphones radio modems eclipse capacity early ethernet due developments standards known umts mimo boost bandwidth maximizing antenna usage extrapolating forward indicates convergence rates nomadic wireless technologies around 2030 addition wireless technology could end wireline communication cost latter infrastructure remains high edholm law predicted required data rates double every 18 months proven true last decade trend evident 16 years cases cellular wireless lan wireless personal area networks
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Computer architecture
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synchronous transmit-receive synchronous transmit-receive str early ibm character-oriented communications protocol preceded bisync str point-to-point employed four-of-eight transmission code communicating 5100 characters per second half-duplex full-duplex communication lines ibm 1009 data transmission unit ibm 1130 synchronous communications adapter ibm system/360 model 20 communications adapter ibm 2701 data transmission unit provided host computer support str ibm 7701 ibm 7702 magnetic tape transmission terminal ibm 1013 card transmission terminal ibm 7710 ibm 7711 data communication units among remote devices supported str str still supported 1972 although generally faded use four-of-eight code 64 character set plus six control characters encoded eight bits exactly four bits character one bits — 70 possible bit combinations four-of-eight code first column graphics 7701 graphic shown code unassigned plus zero minus zero distinct values many machines shown +0 -0 second column graphics 1130 sca graphics shown different 7701 mostly characters ebcdic character set present bcd synchronous transmit-receive control codes control characters reserved provision transparent operation longitudinal redundancy check byte character could four one bits byte contains zero bit position data record contained even number one bits one odd number idle characters control sequences included lrs data transmitted line maintained synchronize mode — terminal transmits idle characters approximately 1.3 seconds followed end-of-idle sequence codice_1 listens sequence approximately three seconds four wire operation data transmitted wire pair maintained synchronize mode least one idle character sent transmission ownership line established transmitting station sending inquiry sequence codice_2 receiving terminal responds acknowledge codice_3 following initiation sequence transmitting terminal sends codice_4 followed first block data data terminated end-of-transmittal-record codice_5 receiving terminal replies codice_6 codice_7 longitudinal redundancy check indicates transmission error process continues even/odd codice_8 codice_9 sending terminal transmitted data sends end-of-transmission sequence codice_10 receiving terminal responds codice_10 re-enters synchronize mode
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Internet protocols
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openlisp openlisp programming language lisp family developed christian jullien conforms international standard islisp published jointly international organization standardization iso international electrotechnical commission iec iso/iec 13816:1997 e revised iso/iec 13816:2007 e written programming languages c lisp runs common operating systems openlisp designated islisp implementation also contains many common lisp-compatible extensions hashtable readtable package defstruct sequences rational numbers libraries network socket regular expression xml portable operating system interface posix sql lightweight directory access protocol ldap openlisp includes interpreter associated read–eval–print loop repl lisp assembly program lap backend compiler language c. main goal lisp version implement fully compliant islisp system launched codice_1 flag strictly restricted iso/iec 13816:2007 e specification secondary goal provide complete embeddable lisp system linkable c/c++ java via java native interface jni callback mechanism used communicate external program goals usable scripting language glue language produce standalone program executables despite name openlisp proprietary software interpreter available free charge noncommercial use openlisp mainly runs console mode codice_2 microsoft windows terminal emulator unix-based systems alternate solutions include running openlisp emacs via setting emacs codice_3 using integrated development environment ide supports openlisp syntax lispide daansystems natively internally openlisp uses virtual memory allocate extend objects automatically small objects type allocated using bibop big bag pages memory organization large objects use proxy point real object lisp heap conservative garbage collection mark sweep coalescing heap sweep phase configured use threads openlisp uses tagged architecture 4 bits tag 32-bit 5 bits tag 64-bit fast type checking small integer float symbol cons string vector small integers 28 bits 32-bit 59 bits 64-bit unboxed large 32/64-bit integers boxed required islisp arbitrary-precision arithmetic bignums also implemented characters hence strings either 8-bit ansi ebcdic 16/32-bit unicode support enabled lisp kernel native interpreter basic libraries hand coded language c lap intermediate language produced compiler translated c c backend code generator 1988 first motive behind openlisp implement lisp subset extend emact emacs clone islisp became obvious choice quickly development ensued openlisp claims extremely portable runs many operating systems including windows unix posix based linux macos freebsd openbsd netbsd solaris hp-ux aix cygwin qnx dos os/2 pocket pc openvms z/os official website download section contains 50 different versions openlisp interact modules written c using foreign function interface ffi islisp streams extended support network socket codice_4 directory includes samples hypertext transfer protocol http javascript object notation json post office protocol 3 pop3 simple mail transfer protocol smtp telnet rss simplified extensible markup language xml reader convert xml lisp basic sql module used mysql odbc sqlite postgresql comma-separated values csv module read write csv files developer tools include data logging pretty-printer profiler design contract programming unit tests well known algorithms available codice_5 directory dantzig simplex algorithm dijkstra algorithm ford–fulkerson algorithm modules shipped using bsd licenses prefix open refers open systems open-source model name chosen 1993 replace mlisp internal code name already used gosling emacs successor mocklisp openlisp programming language different openlisp project begun 1997 implement locator/identifier separation protocol section describes compiler transforms lisp code c. fibonacci number function classic definition used benchmarks efficient way compute codice_6 lisp compiler translates lisp source code following intermediate code followed peephole optimization pass uses intermediate format analyze optimize instructions optimization final lap code finally c code generator uses lap code translate instructions c. static pointer oldefcompiled1 olfib_00 p1 _l003 _l004 openlisp accepts lines unlimited length recommended style line text code 80 characters per line chosen sdf public access unix system nonprofit public access unix systems internet one programming languages available online bricsys uses openlisp implement autolisp bricscad computer-aided design cad system meva entirely written openlisp università degli studi di palermo uses openlisp teach lisp
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Programming language topics
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comparison programming languages programming languages used controlling behavior machine often computer like natural languages programming languages conform rules syntax semantics thousands programming languages new ones created every year languages ever become sufficiently popular used people professional programmers may use dozens languages career programming languages standardized international national standard even widely used ones perl standard ml despite name notable standardized programming languages include algol c c++ javascript name ecmascript smalltalk prolog common lisp scheme ieee standard ada fortran cobol sql xquery following table compares general technical information selection commonly used programming languages see individual languages articles information please note following table may missing information programming languages print error message throw exception input/output operation system call e.g. chmod kill fails unless programmer explicitly arranged different handling events thus languages fail safely regard mostly older languages require programmer explicitly add checks kinds errors psychologically different cognitive biases e.g. optimism bias may affect novice experts alike omissions lead erroneous behavior literature programming languages contains abundance informal claims relative expressive power framework formalizing statements deriving interesting consequences table provides two measures expressiveness two different sources additional measure expressiveness gzip bytes found computer language benchmarks game benchmarks designed mimic particular type workload component system computer programs used compiling benchmark data section may fully optimized relevance data disputed accurate benchmarks customized particular situation people benchmark data may value others proper interpretation brings many challenges computer language benchmarks game site warns over-generalizing benchmark data contains large number micro-benchmarks reader-contributed code snippets interface generates various charts tables comparing specific programming languages types tests
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Programming language topics
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metadata repository metadata repository database created store metadata metadata information structures contain actual data metadata often said data data misleading data profiles example actual data data metadata one layer abstraction removed – data structures contain data metadata may describe structure data subject stored format well-designed metadata repository typically contains data far beyond simple definitions various data structures typical repositories store dozens hundreds separate pieces information data structure comparing metadata couple data items one digital one physical help one understand metadata really first digital data stored database one may table called patient many columns containing data describes different attribute patient one columns may named patient_last_name metadata column contains actual surnames patients database already used two items name column contains data patient_last_name name table contains column patient metadata might include maximum length last name may entered whether last name required patient without patient_last_name whether database converts surnames entered lower case upper case metadata security nature may show restrictions limit may view names second physical data stored brick mortar library one many volumes may various media including books metadata books would include isbn binding_type page_count author etc within binding_type metadata would include possible bindings material etc contextual information business data include meaning content policies govern technical attributes specifications transform programs manipulate metadata repository responsible physically storing cataloging metadata data metadata repository generic integrated current historical generic meta model store metadata generic terms instead storing applications-specific defined way data base standard changes one product another physical meta model metadata repository would need change integration metadata repository allows business areas metadata integrated fashion covering domains subject areas organization metadata repository accessible current historical metadata metadata repositories used referred data dictionary transition needs metadata usage business intelligence increased scope metadata repository increased earlier data dictionaries closest place interact technology business data dictionaries universe metadata repository initial stages scope increased business glossary tags variety status flags emerged business side consumption technology metadata lineage linkages made repository source valuable reports bring business technology together helped data management decisions easier well assess cost changes metadata repository explores enterprise wide data governance data quality master data management includes master data reference data integrates wealth information integrated metadata across organization provide decision support system data structures even though reflects structures consumed various systems repository additional functionalities compared registry metadata repository stores metadata like metadata registry also adds relationships related metadata types metadata related flow point entry organization deliverables considered lineage data point metadata related across related metadata types called linkages providing relationships metadata points across organization maintaining integrity architecture handle changes metadata repository provides basic material understanding complete data flow definitions impact also important feature maintain version control though statement contrasting open discussion definitions still evolving accuracy definitions needs refinement purpose registry define metadata element maintained across organization data models data management teams refers registry changes follow metadata repository sources metadata various metadata systems organizations reflects upstream repository never acts upstream registry used upstream metadata changes metadata repository enables structure organizations data containers one integrated place opens plethora resourceful information making calculated business decisions tool uses one generic form data model integrate models thus brings applications programs organization one format top applying business definitions business processes brings business technology closer help organizations make reliable roadmaps definite goals one stop information business control changes impact analysis tool usually business spends lots time money make decisions based discovery research impacts make changes add new data structures remove structures data management organization structured well maintained repository moving product ideation delivery takes least amount time considering variables constant sum database management system dbms database tools language metadata components within database applications already repositories registries expected provide necessary functionality access data stored within vendors want companies capable easily migrating data away products competitors products proprietary way handle metadata case tools dbms dictionaries etl tools data cleansing tools olap tools data mining tools handle store metadata differently metadata repository designed store metadata components tools metadata repositories store metadata four classifications ownership descriptive characteristics rules policies physical characteristics ownership showing data owner application owner descriptive characteristics define names types lengths definitions describing business data business processes rules policies define security data cleanliness timelines data relationships physical characteristics define origin source physical location like building logical data model creating database logical meta model help identify metadata requirements business data metadata repository centralized decentralized distributed centralized design means one database metadata repository stores metadata applications business wide centralized metadata repository advantages disadvantages centralized database easier manage data one database disadvantage bottlenecks may occur decentralized metadata repository stores metadata multiple databases either separated location departments business makes management repository involved centralized metadata repository advantage metadata broken individual departments distributed metadata repository uses decentralized method unlike decentralized metadata repository metadata remains original application xml gateway created acts directory accessing metadata within different application advantages disadvantages distributed metadata repository mirror distributed database design information model include various layers metadata types overlapped create integrated view data various metadata types stitched related metadata elements top model linking business glossary layers metadata metadata repositories designed either entity-relationship model object-oriented design
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Databases
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github github american company provides hosting software development version control using git subsidiary microsoft acquired company 2018 7.5 billion offers distributed version control source code management scm functionality git well adding features provides access control several collaboration features bug tracking feature requests task management wikis every project github offers plans free professional enterprise accounts free github accounts commonly used host open source projects january 2019 github offers unlimited private repositories plans including free accounts may 2019 github reports 37 million users 100 million repositories including least 28 million public repositories making largest host source code world github developed chris wanstrath p. j. hyett tom preston-werner scott chacon using ruby rails started february 2008 company github inc. existed since 2007 located san francisco february 24 2009 github team members announced talk yahoo headquarters within first year online github accumulated 46,000 public repositories 17,000 formed previous month alone time 6,200 repositories forked least 4,600 merged july 5 2009 github announced site harnessed 100,000 users july 27 2009 another talk delivered yahoo preston-werner announced github grown host 90,000 unique public repositories 12,000 forked least total 135,000 repositories july 25 2010 github announced hosting 1 million repositories april 20 2011 github announced hosting 2 million repositories june 2 2011 readwriteweb reported github surpassed sourceforge google code total number commits period january may 2011 july 9 2012 peter levine general partner github investor andreessen horowitz stated github growing revenue 300 annually since 2008 profitably nearly entire way january 16 2013 github announced passed 3 million users mark hosting 5 million repositories december 23 2013 github announced reached 10 million repositories june 2015 github opened office japan first office outside u.s. july 29 2015 github announced raised 250 million funding round led sequoia capital round valued company approximately 2 billion 2016 github ranked 14 forbes cloud 100 list february 28 2018 github fell victim second largest distributed denial-of-service ddos attack history incoming traffic reaching peak 1.35 terabits per second june 4 2018 microsoft announced reached agreement acquire github 7.5 billion purchase closed october 26 2018 june 19 2018 github expanded github education offering free education bundles schools june 4 2018 microsoft announced intent acquire github us 7.5 billion deal closed oct. 26 2018 github continue operate independently community platform business microsoft service led xamarin nat friedman reporting scott guthrie executive vice president microsoft cloud ai current ceo chris wanstrath retained technical fellow also reporting guthrie microsoft become significant user github using host open source projects development tools chakra core powershell visual studio code backed open source projects linux developed virtual file system git vfs git formerly git virtual file system gvfs —a git extension managing large-scale repositories adopted github concerns developers kyle simpson javascript trainer author rafael laguna ceo open-xchange microsoft purchase citing uneasiness microsoft handling previous acquisitions nokia mobile business skype saw culmination microsoft recent changes business strategy ceo satya nadella seen larger focus sale cloud computing services main line business alongside development contributions open source software linux opposed microsoft windows operating system harvard business review argued microsoft intending acquire github get access userbase used loss leader encourage use development products services concerns sale bolstered interest competitors bitbucket owned atlassian gitlab commercial open source product also runs hosted service version sourceforge owned bizx llc reported seen spikes new users intending migrate projects github respective services github inc. originally flat organization middle managers words everyone manager self-management employees could choose work projects interested open allocation salaries set chief executive 2014 github inc. introduced layer middle management github.com start-up business first years provided enough revenue funded solely three founders start taking employees july 2012 four years company founded andreessen horowitz invested 100 million venture capital july 2015 github raised another 250 million venture capital series b round investors sequoia capital andreessen horowitz thrive capital venture capital funds august 2016 github making 140 million annual recurring revenue github mascot anthropomorphized octocat five octopus-like arms character created graphic designer simon oxley clip art sell istock website enables designers market royalty-free digital images github became interested oxley work twitter selected bird designed logo illustration github chose character oxley named octopuss since github wanted octopuss logo use istock license disallows negotiated oxley buy exclusive rights image github renamed octopuss octocat trademarked character along new name later github hired illustrator cameron mcefee adapt octocat different purposes website promotional materials mcefee various github users since created hundreds variations character available octodex march 2014 github programmer julie ann horvath alleged founder ceo tom preston-werner wife theresa engaged pattern harassment led leaving company april 2014 github released statement denying horvath allegations however following internal investigation github confirmed claims github ceo chris wanstrath wrote company blog investigation found tom preston-werner capacity github ceo acted inappropriately including confrontational conduct disregard workplace complaints insensitivity impact spouse presence workplace failure enforce agreement spouse work office preston-werner resigned company 2017 allegations made discriminatory unsupportive behavior github developer recruited following commitment github improve diversity inclusivity development github platform began october 19 2007 site launched april 2008 tom preston-werner chris wanstrath p. j. hyett scott chacon made available months prior beta release projects github accessed manipulated using standard git command-line interface standard git commands work github also allows registered non-registered users browse public repositories site multiple desktop clients git plugins also created github third parties integrate platform site provides social networking-like functions feeds followers wikis using wiki software called gollum social network graph display developers work versions forks repository fork branch within fork newest user must create account order contribute content site public repositories browsed downloaded anyone registered user account users able discussions manage repositories submit contributions others repositories review changes code github began offering unlimited private repositories cost january 2019 limited three contributors per project previously public repositories free fundamental software underpins github git written linus torvalds creator linux additional software provides github user interface written using ruby rails erlang github inc. developers wanstrath hyett preston-werner github mostly used code addition source code github supports following formats features github terms service require public software projects hosted github meet open source definition reason essential users developers intending use piece software found github read software license repository usually found top-level file called license license.txt similar determine meets needs terms service state setting repositories viewed publicly agree allow others view fork repositories github enterprise similar github public service designed use large-scale enterprise software development teams enterprise wishes host repositories behind corporate firewall cloud enterprises privately run github cloud premises two environments linked work together github pages static web hosting service offered github since 2008 github users hosting user blogs project documentation even whole books created page github pages content stored git repository either files served visitors verbatim markdown format github seamlessly integrated jekyll static web site blog generator github continuous integration pipelines time content source updated jekyll regenerates website automatically serves via github pages infrastructure rest github includes free paid tiers service instead supported web advertising web sites generated service hosted either subdomains github.io domain custom domains bought third-party domain name registrar github also operates services pastebin-style site called gist hosting code snippets github proper hosting larger projects tom preston-werner presented then-new gist feature punk rock ruby conference 2008 gist builds traditional simple concept pastebin adding version control code snippets easy forking ssl encryption private pastes gist git repository multiple code snippets contained single paste pushed pulled using git forked code pushed back original author form patch gists pastes become like mini-projects github launched new program called github student developer pack give students free access popular development tools services github partnered bitnami crowdflower digitalocean dnsimple hackhands namecheap orchestrate screenhero sendgrid stripe travis ci unreal engine launch program 2016 github announced launch github campus experts program train encourage students grow technology communities universities campus experts program open university students 18 years older across world github campus experts one primary ways github funds student oriented events communities campus experts given access training funding additional resources run events grow communities become campus expert applicants must complete online training course consisting multiple modules designed grow community leadership skills github also provides software service integrations adding extra features projects services include site https //github.community/ github maintains community forum users ask questions publicly answer questions users site https //github.com/sponsors github sponsors allows users make monthly money donations projects hosted github public beta announced may 23 2019 currently project accepts wait list registrations verge said github sponsors works exactly like patreon developers offer various funding tiers come different perks ’ receive recurring payments supporters want access encourage work except zero fees use program furthermore github offer incentives early adopters first year pledges cover payment processing costs match sponsorship payments 5,000 per developer furthermore users still use similar services like patreon open collective link websites july 25th 2019 developer based iran wrote medium github blocked private repositories prohibited access github pages soon github confirmed blocking developers iran crimea cuba north korea syria accessing private repositories however github reopened access github pages days later public repositories regardless location also revealed using github visiting sanctioned countries could result similar action occurring user account github responded complaints media spokesperson saying github subject us trade control laws committed full compliance applicable law time github vision global platform developer collaboration matter developers reside result take seriously responsibility examine government mandates thoroughly certain users customers impacted beyond required law includes keeping public repositories services including open source projects available accessible support personal communications involving developers sanctioned regions developers feel restrictions appeal removal said restrictions including travel reside countries github forbidden use vpns ip proxies access site sanctioned countries purchase history ip addresses flag users among sources december 3 2014 github blacklisted russia github initially refused take user-posted suicide manuals day russia withdrew block december 31 2014 github blocked india along 31 websites pro-isis content posted users january 10 2015 github unblocked march 26 2015 github fell victim massive ddos attack lasted 118 hours attack appeared originate china primarily targeted github-hosted user content describing methods circumventing internet censorship october 8 2016 github access blocked turkish government prevent email leakage hacked account belonging country energy minister july 25 2019 github started blocking developers countries facing us trading sanctions prominent open source organizations projects use github primary place collaboration including
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Distributed computing architecture
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lavarand lavarand hardware random number generator designed silicon graphics worked taking pictures patterns made floating material lava lamps extracting random data pictures using result seed pseudorandom number generator although secondary part random number generation uses pseudorandom number generator full process essentially qualifies true random number generator due random seed used however applicability limited low bandwidth covered titled method seeding pseudo-random number generator cryptographic hash digitization chaotic system 1997 2001 web site lavarand.sgi.com demonstrating technique landon curt noll one originators went help develop lavarnd use lava lamps despite short life lavarand.sgi.com often cited example online random number source 2017 cloudflare maintains similar system lava lamps securing approximately 10 internet traffic
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Computer architecture
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tasman layout engine tasman discontinued browser engine developed microsoft inclusion macintosh version internet explorer 5 tasman attempt improve support web standards defined world wide web consortium time release tasman seen layout engine best support web standards html css internet explorer mac longer supported newer versions tasman incorporated microsoft products tantek çelik led software team developed tasman engine tasman later became used layout engine msn mac os x office 2004 mac first version tasman referred v0 released internet explorer 5 macintosh edition march 27 2000 upgraded version version 0.1 followed release internet explorer 5.1 mac may 15 2003 microsoft released subscription-only msn mac os x browser used upgraded version tasman version 0.9 layout engine posting mac internet explorer talk list internet explorer mac program manager jimmy grewal listed improvements tasman improved part number tv set-top box projects microsoft reaching version 1.0 tasman engine used microsoft tv mediaroom edition may 11 2004 microsoft started shipping microsoft office 2004 mac incorporates version tasman layout engine email client entourage since microsoft office mac 2011 entourage replaced macintosh version microsoft outlook uses webkit-based layout engine used safari instead
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Internet protocols
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telecom network protocol analyzer telecom network protocol analyzer protocol analyzer analyze switching signaling telecommunication protocol different nodes pstn mobile telephone networks 2g 3g gsm networks cdma networks wimax mobile telecommunication network analyze traffic msc bsc bsc bts msc hlr msc vlr vlr hlr protocol analyzers mainly used performance measurement troubleshooting devices connect network calculate key performance indicators monitor network speed-up troubleshooting activities
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Computer security
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malwarebytes malwarebytes inc. american internet security company offices santa clara california clearwater florida tallinn estonia cork ireland specializes protecting home computers smartphones companies malwarebytes formally established january 2008 marcin kleczynski bruce harrison ceo vice president research malwarebytes respectively though origins company date back 2004 kleczynski became involved forums discussing computer viruses 2011 malwarebytes acquired hphosts website blacklisting company tracks blacklisted websites ad servers june 2015 company announced moving headquarters 10 almaden boulevard san jose california new office space two top floors 12-story 3979 freedom circle santa clara company reported growth 10 million users one year 2014–2015 increase revenue 1653 2014 2015 malwarebytes fixed 250 million computers five billion malware threats worldwide several malwarebytes products become well known computer world malwarebytes anti-malware available two different versions one free download home computers professional version 14-day free trial advance malwarebytes anti-exploit uses exploit mitigation protect vulnerable programs attack endpoint security advanced anti-ransomware technology package unveiled january 2016 three products incorporated single program called malwarebytes 3.0 premium paid program 14-day free trial period malwarebytes anti-exploit longer available free standalone product malwarebytes inc. informally established 2004 ceo founder marcin kleczynski originally poland still teenager attending high school bensenville illinois time working technician computer repair shop chicago noticed whenever infected computers arrived would generally reformat computer regardless infection minor mother computer became infected kleczynski learned virus n't directly attacked finding neither mcafee symantec would remove malware system later recalled 've never angry got computer infected professed mother told fix penalty death kleczynski posted forum spywareinfo popular time able learn cure took three days company unofficially founded kleczynski conversed became friends several editors forum tempted buy unused domain one site regulars bruce harrison kleczynski wrote inaugural version company software 2006 worked college roommate produce freely available program called rogueremover utility specialized fighting type infection known rogues scam computer users giving away credit card information fake anti-virus software rogueremover proved instrumental developing malwarebytes anti-malware kleczynski able set forum enabled improve software feedback kleczynski harrison formally launched malwarebytes january 21 2008 kleczynski studying computer science university illinois bruce became vp research malwarebytes hired doug swanson experience freeware development work new company marcus chung e-commerce expert formerly worked greenborder hired chief operating officer kleczynski harrison reportedly made 600,000 first year selling software despite met personally time 2011 malwarebytes acquired hphosts website blacklisting company tracks blacklisted websites ad servers necessary development protect new internet protocol addresses web servers distribute malware advise internet service providers shut malicious activity year company claimed removed five billion pieces malware three years following year company launched corporate market enterprise product aimed desktop-based anti-malware detection protection 2013 malwarebytes acquired zerovulnerabilitylabs inc. security research development company founded pedro bustamante protects software applications known zero-day exploits used exploit kits web-based vulnerability exploits corporate-targeted attacks expanded malware removal protection android platform launch malwarebytes anti-malware mobile launched usb-based product called malwarebytes techbench aimed helping technicians remove malware 2014 malwarebytes received 30 million funding highland capital following year announced treated 250 million computers worldwide representing 20–25 working business computers 2013 claimed removed five billion malware threats computers first five years june 2015 company announced moving headquarters 10 almaden boulevard san jose california new office space two top floors 12-story 3979 freedom circle santa clara california new office twice size former office company reported growth 10 million users one year 25 35 million active users time increase revenue 1653 2014 2015 kleczynski named one forbes magazine '30 30 january 2016 malwarebytes unveiled advanced anti-ransomware package endpoint security announced raised 50 million investment fidelity management research company kleczynski stated funds would used primarily company hiring product development marketing assets june malwarebytes announced strong growth sales 75 percent first quarter year compared 2015 billings surpassing 100 million corporate subscription base company reported grown 90 september proofpoint inc. ceo gary steele joined company board directors kleczynski citing deep expertise security software industry proven ability increasing sales revenue main reasons appointment october company purchased adwcleaner windows program used clean adware computers february 2017 company acquired saferbytes italian security start-up specialized anti-malware anti-exploit anti-rootkit cloud av sandbox technologies december 2016 malwarebytes anti-malware updated built ground combined 3 flagship products anti-malware anti-exploit anti-ransomware renamed malwarebytes anti-malware malwarebytes malwarebytes also functions anti-virus according release statement ceo marcin kleczynski states malwarebytes engine advantage many traditional antivirus programs developed 2008 many others developed late 1990s little idea malware would look like 15 years line states makes easier us adapt malware evolves new york times describes system hybrid heuristics behavior signature engine designed detect block malware vendors ca n't detect according dean takahashi venturebeat malwarebytes complements antivirus software vendors symantec mcafee anti-malware working anti-virus software attack problem different directions remarked malwarebytes cleans machines already infected pro version stops machine getting infected first place early development days rogueremover malwarebytes thrives community feedback runs two sub-forums complementing main forum known false positives malware contribution false positives reported allowing company update database within hours malware contribution allowing quickly report missing download kleczynski quoted saying still try work like bootstrapped company 'd rather build products customers buy rather sell something may need. ” malwarebytes several products 2011 available 36 different languages malwarebytes anti-malware offers two different versions one free download home computers professional version 14-day free trial advance offering real-time protection malware automated scanning automatic updating malwarebytes anti-malware mobile free android app protects smartphones mobile malware preventing unauthorized access personal data identifying tracking applications rating 4.4 google play store 2014 company launched malwarebytes anti-malware 2.0 improved user interface dashboard 2014 company launched malwarebytes anti-exploit shields selected applications attacks exploit mitigation protect vulnerable programs anti-exploit also comes free paid version windows computers free version stops exploits browsers java whilst paid product adds protection wider range software applications anti-exploit received four stars pc magazine v3 magazine security innovation year award 2016 malwarebytes anti-exploit merged premium version malwarebytes version 3.0 standalone application offered perpetual beta july 2015 malwarebytes acquired adwaremedic released malwarebytes anti-malware mac detects malware adware potentially unwanted programs macintosh computers january 2016 malwarebytes unveiled malwarebytes endpoint security advanced anti-ransomware technology described first solution offer multiple layers protection unknown ransomware company sponsored survey osterman research 540 firms united states united kingdom canada germany found nearly 40 companies experienced ransomeware incidents 34 percent accounted loss revenue guardian reported one-fifth british companies charged 10,000 unlock files increasing demand anti-ransomeware technology endpoint inception beta reportedly downloaded 200,000 businesses consumers first six months year malwarebytes also numerous tools junkware removal tool remove adware anti-rootkit beta remove repair rootkits startuplite boost speed windows reboot fileassassin prevent locked files software license requires arbitration county reside forbids class action suits reverse engineering sharing limits warranties liability even free version may shared since track use separately user malwarebyte privacy policy lists many types information collect store including software running user computer programs installed use malwarebytes says collect name email address mailing address phone number ... company name company size business type ... internet protocol ip addresses browser type internet service provider isp referring/exit pages files viewed site ... operating system date/time stamp and/or clickstream data ... type device use operating system version unique device identifier ... language ... 32- 64-bit ... information windows security/action center including security settings programs installed use ... license ... represents console system number seats managed installation console endpoint domain information ... organization ip address licensed different limits use sale sharing data general put time limits long keep data except ip address users ask deletion pii text says save locations ip addresses including mobile devices go get gps locations mobile devices ask access track location based information mobile device time downloading using mobile apps services say get antenna locations also collect detailed information malware exploits find tied user license number device identifier vendor ... file path exploit process ... command-line arguments passed exploit ... potentially copy exploit executable list license number pii certificate truste among things certifies company limits information collected limits use specified privacy notice 2018 key individuals working malwarebytes included
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Computer security
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fexpr lisp programming languages fexpr function whose operands passed without evaluated fexpr called body fexpr evaluated evaluations take place except explicitly initiated fexpr contrast ordinary lisp function called operands evaluated automatically results evaluations provided function traditional lisp macro called operands passed unevaluated whatever result macro function returns automatically evaluated early lisp environment mapped symbol association list rather directly value standard keys lists included two keys used store data value looked symbol occurred argument four keys used store function looked symbol occurred operator function keys indicated compiled ordinary function whose operands evaluated passed indicated compiled special form whose operands passed unevaluated indicated user-defined ordinary function indicated user-defined special form difference fexpr expr whether operands automatically evaluated strict original usage fexpr therefore user-defined function whose operands passed unevaluated however later usage term fexpr may describe first-class function whose operands passed unevaluated regardless whether function primitive user-defined simple illustration fexprs work fexpr definition written kernel programming language similar scheme convention kernel names fexprs always start definition provides fexpr called takes three operands fexpr called local environment created extending static environment fexpr defined local bindings created symbols bound three operands call fexpr symbol bound dynamic environment fexpr called body fexpr ... evaluated local environment result evaluation becomes result call fexpr net effect first operand evaluated dynamic environment depending whether result evaluation non-negative either second third operand evaluated result returned operand either third second evaluated example statically scoped local environment extension static environment 1980 lisp languages supported fexprs mainly dynamically scoped local environment extension dynamic environment rather static environment however still sometimes necessary provide local name dynamic environment avoid capturing local parameter names fexpr support continued lisp 1.5 last substantially standard dialect lisp fragmented multiple languages 1970s two dominant lisp languages — maclisp interlisp — supported fexprs 1980 conference lisp functional programming kent pitman presented paper special forms lisp discussed advantages disadvantages macros fexprs ultimately condemned fexprs central objection lisp dialect allows fexprs static analysis determine generally whether operator represents ordinary function fexpr — therefore static analysis determine whether operands evaluated particular compiler tell whether subexpression safely optimized since subexpression might treated unevaluated data run-time since decline maclisp interlisp two lisp languages risen dominance 1993 — scheme common lisp — support fexprs newlisp support fexprs calls macros picolisp built-in functions fsubrs lisp-level functions exprs fexprs lexprs mixture starting brian smith 3-lisp 1982 several experimental lisp dialects devised explore limits computational reflection support reflection lisps support procedures reify various data structures related call — including unevaluated operands call makes procedures fexprs late 1990s fexprs become associated primarily computational reflection theoretical results fexprs obtained 1993 john c. mitchell used lisp fexprs example programming language whose source expressions formally abstract concrete syntax source expression always extracted context operand fexpr 1998 mitchell wand showed adding fexpr device lambda calculus — device suppresses rewriting operands — produces formal system trivial equational theory rendering impossible make source-to-source optimizations without whole-program analysis 2007 john n. shutt proposed extension lambda calculus would model fexprs without suppressing rewriting operands attempt avoid wand result following languages implement fexprs near equivalents
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Programming language topics
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tads text adventure development system tads prototype-based domain-specific programming language set standard libraries creating interactive fiction games original tads 1 released high energy software shareware 1988 followed tads 2 long early 1990s tads established number one development tool interactive fiction place simpler systems like agt adventure game toolkit late 1990s joined inform popular interactive fiction development language tads 2 syntax based c bits pascal tads 2 maintained updated regular intervals creator michael j. roberts even became freeware july 1996 graham nelson creator inform describes inform tads two systems ... widely used last half 1990s tads called second commonly used programming language today multimedia tads introduced 1998 allows games display graphics animation play sounds platform supports 2006 tads received major overhaul release tads 3 complete rewrite tads engine retaining platform-dependent code ease porting tads 3 uses language syntax resembles c++ java many new features efficient dynamic objects automatic garbage collection structured exceptions native utf-8 strings many useful function classes tads 3 compiler interpreter ported dos macintosh unix platforms several tads 3 games released games written tads compiled platform-independent format played computer suitable virtual machine vm exists virtual machines exist several platforms respect tads closely follows example original infocom z-machine well modern languages java c whereas tads 1 2 vms parse commands entered player sending results game tads 3 employs general-purpose virtual machine command-parsing done game code akin inform rationale easier customize parser
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Programming language topics
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inform inform programming language design system interactive fiction originally created 1993 graham nelson inform generate programs designed z-code glulx virtual machines versions 1 5 released 1993 1996 around 1996 nelson rewrote inform first principles create version 6 inform 6 following decade version 6 became reasonably stable popular language writing interactive fiction 2006 nelson released inform 7 briefly known natural inform completely new language based principles natural language new set tools based around book-publishing metaphor versions inform generate files z-code also called story files source code files run z-code interpreter – program properly implements z-code virtual machine z-machine specification z-machine originally developed infocom 1979 interactive fiction titles least one interpreter nearly every major minor platform means z-code file run multitude platforms alterations andrew plotkin created unofficial version inform 6 also capable generating files glulx virtual machine designed overcome many limitations several-decades-old z-machine starting inform 6.3 released february 29 2004 inform 6 included official support virtual machines based andrew plotkin work early release inform 7 support glulx august 2006 glulx support released inform originally created graham nelson 1993 1996 nelson rewrote inform first principles create version 6 inform 6 following decade version 6 became reasonably stable popular language writing interactive fiction inform 6 system consists two major components inform compiler generates story files inform source code inform library suite software handles difficult work parsing player text input keeping track world model name inform also refers inform programming language compiler understands although inform 6 z-machine originally designed interactive fiction mind many programs developed including basic interpreter lisp tutorial complete interpreter tetris game version game snake inform compiler generates files z-machine glulx also called story files inform 6 source code inform programming language object-oriented procedural key element language objects objects maintained object tree lists parent–child relationships objects since parent–child relationship often used represent location object parent another object often said hold objects moved throughout tree typically top level objects represent rooms locations within game may hold objects representing room contents physical items non-player characters player character background effects objects hold objects codice_1 object might hold codice_2 object holding codice_3 object contains codice_4 object early versions inform objects different notion objects object-oriented programming thing class later versions added support class definitions allowed objects members classes objects classes inherit multiple classes interactive fiction games typically contain many unique objects many objects inform inherit class metaclass object however objects frequently attributes boolean properties codice_5 codice_6 recognized inform library languages would normally implemented via inheritance simple example inform 6 source code inform system also contains inform library automates nearly difficult work involved programming interactive fiction specifically includes text parser makes sense player input world model keeps track things objects properties rooms doors player inventory etc inform compiler require use inform library several replacement libraries available platypus informate library codes inform spanish example inform 6 source code makes use inform library inform 6 code sample usable inform 7 without special demarcation indicating embedded legacy code april 30 2006 graham nelson announced beta release inform 7 rec.arts.int-fiction newsgroup inform 7 consists three primary parts inform 7 ide development tools specialized testing interactive fiction inform 7 compiler new language standard rules form core library inform 7 inform 7 also relies inform library inform compiler inform 6 compiler compiles inform 7 source code inform 6 source code compiled separately inform 6 generate glulx z-code story file inform 7 also defaults writing blorb files archives include z-code together optional cover art metadata intended indexing purposes full set inform 7 tools currently available mac os x microsoft windows linux march 25 2007 release added command line support linux new releases include ide using gnome desktop environment gnome inform 7 sourceforge project language tools remain development march 25 2007 release included number changes language inform 7 named natural inform brief period time later renamed inform 7 old name inform 7 compiler named ni inform 7 comes integrated development environment ide mac os x microsoft windows linux mac os x ide developed andrew hunter microsoft windows ide developed david kinder linux ide known gnome inform developed philip chimento inform 7 ide includes text editor editing inform 7 source code like many programming editors features syntax highlighting marks quoted strings one color headings organizational sections volumes books chapters parts sections bolded made larger comments set different color made slightly smaller ide includes built-in z-code interpreter mac os x ide interpreter based zoom interpreter andrew hunter contributions jesse mcgrew microsoft windows ide interpreter based winfrotz developer tests game built-in interpreter progress tracked skein transcript views ide skein tracks player commands tree branching possibilities branch tree quickly re-followed making possible retry different paths game development without replaying portions game paths also annotated notes marked solutions exported text walkthroughs transcript hand tracks player commands game responses correct responses game marked blessed replaying transcript branch skein variations blessed version highlighted help developer find errors ide also provides various indices program development code shown class hierarchy traditional map book-like table contents forms clicking items index jumps relevant source code ide presents two side-by-side panes working pane contain source code worked current status compilation skein transcript indices source code running version game documentation inform 7 installed extensions settings concept imitate author manuscript book presenting two facing pages instead multitude separate windows notable features include strong bias towards declarative rule-based style programming ability infer types properties objects way used example statement john wears hat creates person called john since people capable wearing things creates thing wearable property since objects marked wearable capable worn sets john wearing hat another notable aspect language direct support relations track associations objects includes automatically provided relations like one object containing another object worn developer add his/her relations developer might add relations indicating love hatred beings track characters game met inform 7 highly domain-specific programming language providing writer/programmer much higher level abstraction inform 6 highly readable resulting source code statements inform 7 take form complete sentences blank lines indentation places structurally significant basic form inform 7 program follows following reimplementation hello deductible example written inform 7 relies library known standard rules automatically included inform 7 compilations mystery house possessed 2005 emily short first inform 7 game released public released part mystery house taken project march 1 2006 short announced release three games bronze example traditional puzzle-intensive game damnatio memoriae follow-up award-winning inform 6 game savoir-faire joined graham nelson reliques tolti-aph 2006 inform 7 public beta announced april 30 2006 six worked examples medium large scale works made available along source code including three games previously released march 1 emily short floatpoint first inform 7 game take first place interactive fiction competition also 2006 xyzzy awards best setting best npcs rendition nespresso 2007 political art experiment form text adventure game approach tragedy discussed academically association computing machinery cambridge university
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Programming language topics
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true basic true basic variant basic programming language descended dartmouth basic—the original basic created college professors john g. kemeny thomas e. kurtz true basic traces history offshoot dartmouth basic called structured basic sbasic short released sometime 1975 1976 installed mainline version basic dartmouth time sharing system dtss supported campus shortly kemeny became involved effort produce ansi standard basic attempt bring together many small variations language developed late 1960s early 1970s effort initially focused system known minimal basic similar early dartmouth basic string variables added later work aimed standard basic essentially sbasic early 1980s tens millions home computers running variation microsoft basic become de facto standard ansi efforts eventually became pointless became clear versions going market impact world dominated ms versions eventually ratified saw little adoption standards later withdrawn kemeny kurtz however decided continue efforts introduce concepts sbasic ansi standard basic efforts became true basic initially based dartmouth basic 7—otherwise known ansi basic—true basic introduced 1985 versions true basic compiler ms-dos microsoft windows classic mac os one time versions trs-80 color computer amiga atari st computers offered well unix command-line compiler structured programming implementation language dispenses need line numbers goto statements although still used true basic provides statements matrix arithmetic feature present dartmouth basic since early times dropped almost microcomputer versions basic interpreters supports global local variables permits recursive functions subroutines written designers wanted make language hardware-independent allow true basic source code run equally well version compiler part succeed endeavor drawback users direct access features machines available could remedied callable functions subroutines specially written assembly language using newer versions true basic older functions blocked example recent code would like simple program plots text welcome ... top left-hand corner screen continues never-ending loop plotting fabulous wikipedia random coordinates example simple animation could like jerry pournelle 1985 asked need true basic n't seem anything regular basic n't n't attacked logical intuitive manner criticized lack output encountering error preventing interactive debugging inserting print statements diagnostics pournelle concluded think 'll pass opportunity become born-again true basic believer 'll enjoy microsoft cbasic heresies users complained programs editor using 100 cpu core appears caused editor user programs using loop constantly polls keyboard mouse events problem known since least end 2010 yet early 2014 still worked
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Programming language topics
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fatpaint fatpaint free online web-based graphic design desktop publishing software product image editor includes integrated tools creating page layout painting coloring editing pictures photos drawing vector images using dingbat vector clipart writing rich text creating ray traced 3d text logos displaying graphics products zazzle purchased sold fatpaint integrates desktop publishing features brush painting vector drawing custom printed products single flash application supports use pressure-sensitive pen tablet allows user add images searching wikimedia picasa flickr google yahoo bing fatpaint collection public domain images completed project saved fatpaint server locally fatpaint affiliated zazzle owned mersica also developer makewebvideo fatpaint launched may 2010 five years development danish-brazilian software developer mario gomes cavalcanti cavalcanti ceo graduated object oriented software developer worked computer games industry departure involved development two denmark visited websites responsible developing running fatpaint partner kenneth christensen mastered assembler graphics programming amiga computer spent years mario amiga demo scene according ceo kenneth helped linux servers handled development administration promotion video production testing content founder fatpaint also created make web video video maker web application creating video presentations business families individuals video maker allows users give videos personal business use simple affordable way fatpaint provides free online logo maker graphic design vector drawing photo editor paint design english danish portuguese users change photo colours manipulating r g b channels saturation contrast brightness hue gamma sharpness tint rgba matrix users also remove unwanted background artifacts using paint tools added effects cloning multiple photos combined single image users pick different blend modes multiple layers users also extract change parts photo cropping resizing skewing bending distorting rotating 2d 3d hence users graphics printed custom products bought sold personal business purposes users choose 5000 vector images draw vector graphics art scratch using fatpaint vector shape creation tools also provides advanced symmetric vector transformation 2d 3d well support colour gradients multiple drawings combined form complex vector shapes different blend modes effects supported vector drawings cropped resized skewed distorted rotated 2d 3d similar fatpaint photo editor vector graphics displayed custom printed products purchased sold users personal business uses fatpaint full support pen tablets users pick pen brush airbrush paint bucket clone painting eraser smudging tools fatpaint offers 8 palettes painting plus 13 palettes clone painting fatpaint allows users import create brushes thousands free clipart drawings brush sets dynamic brushes effects blend modes paintings combined different layers objects similarly paintings cropped resized skewed bent distorted rotated 2d 3d moreover graphics displayed custom printed products users buy sell personal business uses fatpaint supports firefox google chrome opera internet explorer cookies javascript enabled browsers may work correctly due support java applets fatpaint requires adobe flash 10 newer sun java 6 newer recommended run windows 7 apple linux java disabled editor works firefox linux java flash integration work linux apple browsers wikimedia search disabled browsers fatpaint works best least 2gb ram 1gb video memory well decent graphics card
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Distributed computing architecture
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fantasy zone game design main character many similarities earlier twinbee together games credited creation cute 'em subgenre numerous sequels made years space year 1422 6216 master system version fantasy zone cast panic collapse interplanetary monetary system space guild brings light plans planet menon whose forces stealing planets currencies fund huge fortress fantasy zone opa-opa sent stop invading army discover behind end turns leader none opa-opa long lost father revelation leaves opa-opa mixed emotions game player ship placed level number bases destroy bases gone stage boss appears must defeated order move next stage eight stages except final one scroll fixed player move either left right although stage loops final level consists rematch previous bosses succession facing final boss opa-opa uses two different attacks standard weapon initially bullets bombs also move land ground sprouting feet walking around flies possible upgrade opa-opa weapons bombs flying engine increase speed well get extra lives player must get money defeating enemies bases bosses access shop touching marked balloon time new item bought become expensive player chooses exit time runs another screen appears select upgrades opa-opa use one engine weapon bomb equipped time new weapons time limit starts soon shop left bombs used moment limited quantity engine upgrades permanent powerups also reassigned reentering shop touch balloon word select written player loses life upgrades lost fantasy zone originally arcade game later ported sega mark iii/master system game eventually saw ports consoles home computers msx famicom/nes snk neo geo sharp x68000 pc engine/turbografx 16 ports play similarly original version several omissions changes instance master system version lacks features radar indicates location bases gauge indicates much energy left two bosses replaced original ones versions several changes well two different versions released famicom/nes japanese version released 1987 developed published sunsoft american unlicensed version released 1989 developed pixel published tengen 1997 fantasy zone released sega ages label japan sega saturn fantasy zone later remade playstation 2 sega ages label although similar appearance arcade version even incorporating original arcade sounds version used polygons instead sprites added stages including bonus levels game takes view behind opa-opa tries collect coins boss defeated moment game mode similar space harrier unreleased space fantasy zone also even though 2up seen score display version single player mode version released north america along remade classic sega titles sega classics collection compilation fantasy zone released mobile phones 2002 japan august 2003 united states due hardware limitations version game divided three different parts march 11 2008 master system version saw re-release japan virtual console europe australia released april 11 2008 north america april 14 2008 territories released price 500 wii points september 18 year sega released another sega ages disc devoted series title fantasy zone complete collection making final release ages series time instead 3d remake disc compiled games series including spin-offs sega ports also included remake fantasy zone ii created system 16 hardware original arcade release also included sonic ultimate genesis collection unlockable game 3d port game released march 19 2014 nintendo 3ds titled 3d fantasy zone opa-opa bros. new features 3ds port involve stereoscopic 3d visuals adjustable difficulty settings ability save game ability switch japanese versions us versions game stage select feature new mode involves player playing upa-upa opa-opa brother addition satisfying certain conditions game enables player confront two replacement bosses master system release entering boss fight literally replacing standard boss fantasy zone also included minigame yakuza 0 unlocked completing one game friendship sidequests identical original arcade release change addition rapid fire button fantasy zone proved successful japanese arcades helping give rise popular system 16 arcade board despite game largely ignored gaming media arcade games time game reviewed 1988 dragon 136 hartley patricia kirk lesser role computers column reviewers gave game 4 5 stars
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Computer architecture
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pamela jones pamela jones commonly known pj creator editor groklaw website covered legal news interest free open-source software community jones open source advocate previously trained worked paralegal jones articles appeared linux journal lwn linuxworld magazine linux today linuxworld.com also wrote monthly opinion column uk print publication linux user developer one contributors book open sources 2.0 continuing evolution 2010 electronic frontier foundation awarded pioneer award pamela jones groklaw website legal blogging jones web site groklaw covered open source legal issues notably sco-linux controversies web site started blog grew groklaw covered various lawsuits involving sco group detail also covered general legal news interest free software open source community site numerous awards including electronic frontier foundation pioneer award 2010 american bar association journal blawg 100 2012 groklaw shut august 20 2013 following lavabit email shutdown way groklaw without email inability privately collaborate without ca n't groklaw without input jones also launched grokline unix ownership timeline project february 2004 grokdoc groklaw spinoff whose original goal create useful manual basic linux tasks new linux users find simple clear easy follow using learn study site also supports many collaborative projects benefit wiki-like structure jones reveals little personal information considers private expressed beginning strong preference avoiding fame reasons gave early days using initials originally wanted stay anonymous sense saying pj eventually media attention factors made impossible remain pj would could desire famous one thing creatively influenced scott mccloud work points understanding comics p. 45–51 section iconic representation people respond strongly drawing character simplifies point anyone identify character guess hoping effect words hoping people could assume whatever wanted focus said rather saying reason chose pj could anyone either sex nationality anyone one particular wanted participation anyone interested sco story politics nothing extraneous effort locate provide evidence could useful knew community could answer sco knew needed
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Operating systems
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vce company vce abbreviation virtual computing environment division emc corporation manufactured converged infrastructure appliances enterprise environments founded 2009 name acadia originally joint venture emc cisco systems additional investments intel emc subsidiary vmware emc acquired 90 controlling stake vce cisco october 2014 giving majority ownership beginning 2016 vce fully integrated emc became converged platform division emc september 7 2016 emc acquired dell converged platform division emc currently known converged platform solutions division dell emc company initially manufactured converged datacenter units known vblock incorporate cisco servers networking hardware emc storage systems vmware virtualization later vxblock added providing ability customers run vmware nsx 2015 vxrack 2016 vxrail added separate products cisco systems emc corporation vmware partially owned emc unveiled joint partnership november 2009 develop cloud computing platforms called vblock infrastructure packages partnership originally called vmware-cisco-emc alliance though name later shortened vce “ virtual computing environment coalition ” emc world trade show cisco emc introduced joint venture named acadia goal acadia originally set separate legal entity build vblock infrastructure packages standardized repeatable fashion customer data centers michael capellas also board member cisco named chairman acadia first chief executive officer ceo may 2010 sales initially encountered confusion among customers often different staffs storage networking example different fiscal quarter sales cycles end 2010 capellas told analysts venture 65 customers average system costing 2.5 million acadia virtual computing environment coalition combined single entity january 2011 called vce virtual computing environment company originally located silicon valley dallas texas expansion announced march 2011 richardson texas investment texas enterprise fund october 2011 another office opened marlboro massachusetts close vce emc-owned manufacturing plant franklin massachusetts july 2012 cisco executive praveen akkiraju appointed ceo frank hauck president estimated vce 1200 employees time undisclosed revenues accumulated losses publicized customers included babson college mississippi community college board press debated venture considered startup company one headline joking vce virtual cash erosion questioning millions dollars executive compensation others considered arrangement wise investment 2012 mixture success speculation layoffs continued confusion due products competing partners netapp flexpod xsigo systems cisco announced framework called cloudverse late 2011 specific vmware august 2012 emc announced vspex reference architecture partnership lenovo distributors seen competing lower-cost option november 2012 report gartner vce 57.4 share integrated infrastructure systems second quarter 2012 based revenue gartner previously tracked server networking external controller-based storage individual markets vce named one “ 2013 virtualization 50 ” crn magazine may 2013 vce estimated 1 billion annual sales rate 1,000 vblock systems sold however us securities exchange commission filings emc accounted cumulative loss 430 million september 2012 cisco loss 457 million early 2013 since revenues recorded owning companies vce emc reported investment 667.2 million cash 13.2 million stock-based compensation vce stake 58 cisco reported gross investment 457 million stake 35 2013 press writers initially criticized vce came view structure vce good business investors press highlighted vce source innovation financial performance investors total vce 2013 reported 1b 50 year-over-year growth rate october 2014 emc announced acquired majority control vce venture cisco maintaining 10 stake january 2016 emc announced vce become converged platform division emc chad sakac president vce marketed converged infrastructure servers known vblocks combine vmware vsphere software running cisco unified computing systems ucs connected cisco nexus switches attached emc symmetrix storage despite block name storage accessed either block device file server vblock systems marketed large-scale datacenters run software applications microsoft exchange server microsoft sharepoint sap erp delivered standard 19-inch rack units aid planning cooling power requirements 2009 virtual computing environment coalition announced three models vblock infrastructure packages vblock 2 intended high-end data centers designed support 3,000 6,000 virtual machines using cisco ucs cisco nexus 1000v multilayer director switches mds well emc symmetrix vmax storage vmware vsphere software vblock 1 intended midmarket designed 800 3,000 virtual machines similar configuration vblock 2 emc clariion storage rather emc symmetrix vmax vblock 0 intended low-end configuration projected release 2010 support 300 800 virtual machines use similar configuration emc celerrastorage term infrastructure package later changed infrastructure platform vblock system vblock brand name vce uses racks containing components data center products prepackaging called converged infrastructure allows customers select preconfigured integrated solutions predictable units power weight cooling geometry data center planning purposes vblock two series based following compositional elements vblock brand naming changed since inception 2009 term vblock infrastructure packages announced acadia technical partnership virtual computing environment coalition well primary investors late 2010 continuing 2011 term packages replaced platforms mid-2012 term infrastructure platforms replaced systems wider circulation arrive simply vblock™ systems meanwhile constituent elements technology included upgrades product lines cisco emc vmware originally combined reference architecture physical logical configuration step initially customer data center colocation data center later within pre-manufacturing environment shipment customer data center colocation data center options limited time marketed sold models named ex fx gx hx later 320 340 350 confirmed numbers announced publicly vce investors 2013 disclosed numbers provided conservatively 800 customers almost 60 countries nearly 2000 vce manufactured vblock systems sold lack manufactured physical logical build actual vce manufacturing floor previous deployments 2009 early 2010 called referred vblock often various use upper lower case spelling considered vblock pundits infrastructure professionals since so-called reference architectures varied greatly project project compared late 2010 manufactured vblock anecdotally institutions companies using vblock involved published testimonials may 2011 vblock system series 300 announced models ex fx gx hx smallest largest vblock 2 renamed 700 series vblock system 700 lx announced emc world may 2012 trade show expensive vblock system supporting thousands virtual machines vce introduced inclusion emc software backup recovery replication business continuity data mobility virtualized environments applications included emc avamar emc data domain emc recoverpoint vblock system 700 included emc vplex workload mobility business continuity software well support new features emc unified infrastructure manager improved vmware integration centralized monitoring multiple vblock systems february 2013 vce announced vblock 300 vblock 700 models increased performance data throughput using upgraded server storage components 2013 vce announced products midrange remote branch office market models included vblock system 100 vblock system 200 vblock 100 designed host 200 virtual machines 24u 42u rack mount space eight cisco c220 m3 blade servers two cisco catalyst 3750-x switches 8 tb storage capacity emc vnxe3150 vnxe3300 array vblock 200 comes configured 12 cisco servers two nexus 5548up unified ethernet san switches cisco catalyst 3750 management switch 105 hard drives via included vnx 5300 array vce introduced specialized system sap hana february 2013 combined vblock system sap hana in-memory computing database application software later september 2013 vce introduced specialized system high performance database oracle well extreme applications vmware citrix vdi environments dell introduced hyperconverged system emc world 2015 february 2015 first model vxrack 1032 based emc scaleio software defined storage second model announced vmware world september 2015 called vxrack 1034 based around vmware vsan models use commodity hardware rumoured sourced quanta attached local disk presented via scaleio vsan software desktop virtualization management software uses vmware view called fastpath announced august 2011 upgraded june 2012 february 2013 vce announced management software application vision intelligent operations software vce vision software enables single management pane components vblock systems manages via plugins third party management automation orchestration tools vmware cisco bmc ca others via restful api snmp unified logging vce provides services partners plan design deploy vblock systems
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Distributed computing architecture
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classic adventure classic adventure also known adventure 1 fantasy text-based video game released abersoft 1982 originally released adventure 1 zx specturm 1982 changed classic adventure 1984-1985 re-released platforms classic adventure remake 1976 text adventure game colossal cave adventure text based game starts opening standing end road small brick building around forest small stream flows building gully player decide explore caves game obstacles must overcome treasure bring back house
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Computer architecture
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deltacloud deltacloud application programming interface api developed red hat apache software foundation abstracts differences cloud computing implementations announced september 3 2009 infrastructure-as-a-service cloud existing today provides api purpose deltacloud provide one unified rest-based api used manage services cloud particular cloud controlled adapter called driver june 2012 drivers exist following cloud platforms amazon ec2 fujitsu global cloud platform gogrid opennebula rackspace rhev-m rimuhosting terremark vmware vcloud next 'classic front-end also offers cimi ec2 front-ends deltacloud used applications aeolus prevent need implement cloud-specific logic may 17 2010 red hat contributed deltacloud apache incubator project graduated incubator october 26 2011 became apache software foundation tlp top-level project july 2013 fujitsu vmware used deltacloud demonstration cimi management developers conference manage cloud infrastructure im may 2013 redhat announced scaling back sponsorship apache deltacloud project effective immediately july 2015 deltacloud moved apache attic due inactivity
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Distributed computing architecture
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houston automatic spooling priority houston automatic spooling priority program commonly known hasp extension ibm os/360 operating system successors providing extended support job management data management task management remote job entry os/360 included spooling routines called reader/interpreters output writers reader/interpreter responsible reading one input job stream – one input device likewise output writer responsible controlling one printer punch spooled data stored os temporary datasets controlled standard os services reader/interpreter output writer separate operating system task partition region system large number readers printers punches might large number spooling tasks hasp developed ibm federal systems division contractors lyndon b. johnson space center houston developers tom simpson bob crabtree hasp program ran mainframe performed functions scheduling control job flow spooling printing/punching hasp support ibm system/360 operating system remote job entry 360s-rc-536 provided roughly equivalent facilities hasp ii v3 nih created shared spool capability hasp used many mainframe sites allowed hasp system share common spool checkpoint enabled workload balancing multi-mainframe environment hasp ii v4 mellon bank greb dave miko moved shared spool version carried forward jes2 multi-access spool ibm formal support hasp mvs 350 copies hasp ii v4 shared spool mods distributed around world shared spool mellon mods added share distribution process could widely accessed program sometimes referred various names indication ibm ever using official documents program became classified part ibm type-iii library competitor asp attached support processor ran one mainframe controlled scheduling attached mainframes asp later became jes3 mvs hasp became jes2 one two job entry subsystems many years hasp labels removed jes2 source messages issued jes2 still prefixed hasp modified version hasp used provide batch spooling remote job entry services michigan terminal system late 1960s 1970s 1980s hasp bypassed operating system services code specially tailored efficiency hasp operated single operating system task used cooperative multitasking internally run processors perform tasks running card readers printers punches managing spool files communicating system operator driving multiple communication lines remote job entry hasp written entirely system/360 assembler typical hasp system might require 86kb memory could virtual memory os/vs systems much would become jes2 jecl part hasp hasp supported ibm terminals 2770 2780 3780 additionally provided support multi-leaving communication intelligent workstations ibm 1130 system/360 model 20 multi-leaving fully synchronous pseudo-simultaneous bi-directional transmission variable number data streams two computers utilizing binary-synchronous communications facilities third party vendors developed variety 2770/2780/3780 simulators multi-leaving implementations use hasp asp vendors incorrectly referred products hasp emulators products actually terminals talked hasp perform functions hasp rje console operator could enter restricted set hasp console operator commands hasp commands precursor jes2 job entry control language jes2 jecl operands restricted remote site hence dj1-999 would display typically still outstanding operator remote site hasp rje console commands could entered short single letter form spelled command line c rm1.rdr meant cancel rather submit current deck cards read might use card jam made sensible let jobs go ahead one cards replaced nearby keypunch hasp job log output provided summary resources used job output appeared caps
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Operating systems
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adobe jrun jrun j2ee application server originally developed 1997 java servlet engine live software subsequently purchased allaire brought first j2ee compliant version acquired macromedia prior 2001 takeover allaire subsequently adobe systems bought macromedia 2005 latest patch updater 7 released adobe 2007 updater 7 added sun jdk 1.6 support apache 2.2 support windows vista/iis7 support mac os x 10.4 intel support adobe announced august 2007 would discontinue new feature development jrun coldfusion team continue make changes underlying java engine required coldfusion 9 replaced jrun favor apache tomcat coldfusion 10
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Web technology
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commando video game commando released japan run gun vertically scrolling arcade game released 1985 unrelated 1985 film name influence seen various later games shooter game genre versions released various home computers consoles game also appears capcom classics collection activision anthology wii virtual console arcade well capcom arcade cabinet playstation 3 xbox 360 player takes control soldier named super joe starts dropped jungle helicopter fight way singlehandedly fending massive assault enemy soldiers super joe armed sub-machine gun unlimited ammunition well limited supply hand grenades joe fire gun eight directions faces grenades thrown vertically towards top screen irrespective direction joe facing unlike submachine gun bullets grenades thrown clear obstacles explosions well-placed grenades kill several enemies end level screen stops player must fight several soldiers streaming gate fortress ordered cowardly officer immediately runs away although shooting back awards player bonus points along way one attempt free prisoners war transported across screen enemy nes version powerful machine gun upgrade well glasses let player view hidden bunkers unlimited grenade upgrade player lose upgrades losing life extra lives given 10,000 points per 50,000 scored 960,000 thereafter lives home version game developed capcom released nintendo entertainment system activision released port game atari 2600 intv released port intellivision also atari 7800 version sculptured software released 1989 elite released versions many home computers bbc micro acorn electron versions developed contract catalyst coders elite developed amiga atari st acorn electron zx spectrum amstrad cpc commodore 64 versions commodore 64 port theme complex extended version arcade music created less 12 hours rob hubbard started working late night worked night took one listen original arcade version started working c64 version ... time everyone arrived 8:00 morning loaded main tune every c64 building got cheque train home 10:00 arcade version re-released virtual console wolf battlefield commando japan october 5 2010 north america december 6 2010 pal region december 17 2010 atari 8-bit version created sculptured software 1989 intended released atari corporation xe game system however although game appeared atari catalogs time never reached market spite completed 2000s game prototype cartridge found computer gaming world said cartridges equal commando non-stop action nes game award best shooting game year according readers crash magazine also voted best arcade-style game year 1986 golden joystick awards nes version sold 1.1 million copies worldwide commando followed sequel titled mercs 1989 known senjō ōkami ii japan second sequel released downloadable title xbox live arcade playstation network 2008 outside japan arcade version bionic commando marketed sequel commando main character nameless soldier game identified super joe american brochure game super joe would appear actual supporting character later versions bionic commando nintendo entertainment system game boy well 2009 version bionic commando playstation 3 xbox 360 character super joe identified joseph gibson one three player characters mercs game duet elite systems ltd also called first commando '86 commando '87
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Computer architecture
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scicoslab scicoslab software package providing multi-platform environment scientific computation based official scilab 4.x build4 distribution includes modeling simulation tool scicos number toolboxes latest stable version scicoslab scicoslab 4.4.2 possible scilab/scicos currently complete alternative commercial packages dynamic systems modeling simulation packages matlab/simulink matrixx/systembuild scicoslab runs available binary format main available platforms like unix/linux workstations microsoft windows macosx scicoslab based scilab scicos forked currently separated new versions evolution order maintain compatibility among
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Programming language topics
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wbxml wap binary xml wbxml binary representation xml developed wap forum since 2002 maintained open mobile alliance standard allow xml documents transmitted compact manner mobile networks proposed addition world wide web consortium wireless application protocol family standards mime media type application/vnd.wap.wbxml defined documents use wbxml wbxml used number mobile phones usage includes exchange activesync synchronizing device settings address book calendar notes emails syncml transmitting address book calendar data wireless markup language wireless village oma drm rights language over-the-air programming sending network settings phone
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Internet protocols
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ciphertext-only attack cryptography ciphertext-only attack coa known ciphertext attack attack model cryptanalysis attacker assumed access set ciphertexts attacker channel providing access plaintext prior encryption practical ciphertext-only attacks attacker still knowledge plaintext instance attacker might know language plaintext written expected statistical distribution characters plaintext standard protocol data messages commonly part plaintext many deployed systems usually guessed known efficiently part ciphertext-only attack systems attack completely successful corresponding plaintexts deduced even better key ability obtain information underlying plaintext beyond pre-known attacker still considered success example adversary sending ciphertext continuously maintain traffic-flow security would useful able distinguish real messages nulls even making informed guess existence real messages would facilitate traffic analysis history cryptography early ciphers implemented using pen-and-paper routinely broken using ciphertexts alone cryptographers developed statistical techniques attacking ciphertext frequency analysis mechanical encryption devices enigma made attacks much difficult although historically polish cryptographers able mount successful ciphertext-only cryptanalysis enigma exploiting insecure protocol indicating message settings advanced ciphertext-only attacks enigma mounted bletchley park world war ii intelligently guessing plaintexts corresponding intercepted ciphertexts every modern cipher attempts provide protection ciphertext-only attacks vetting process new cipher design standard usually takes many years includes exhaustive testing large quantities ciphertext statistical departure random noise see advanced encryption standard process also field steganography evolved part develop methods like mimic functions allow one piece data adopt statistical profile another nonetheless poor cipher usage reliance home-grown proprietary algorithms subject thorough scrutiny resulted many computer-age encryption systems still subject ciphertext-only attack examples include
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Computer security
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ole-johan dahl ole-johan dahl 12 october 1931 – 29 june 2002 norwegian computer scientist dahl professor computer science university oslo considered one fathers simula object-oriented programming along kristen nygaard dahl born mandal norway son finn dahl 1898–1962 ingrid othilie kathinka pedersen 1905–80 seven family moved drammen thirteen whole family fled sweden occupation norway nazi germany end war dahl studied numerical mathematics university oslo dahl became full professor university oslo 1968 gifted teacher well researcher worked hierarchical program structures probably influential publication appeared co-authored c.a.r hoare influential book structured programming 1972 dahl edsger dijkstra hoare perhaps best-known academic book concerning software 1970s career progressed dahl became increasingly interested use formal methods rigorously reason object-orientation example expertise ranged practical application ideas formal mathematical underpinning ensure validity approach dahl widely accepted norway ’ foremost computer scientist kristen nygaard produced initial ideas object-oriented oo programming 1960s norwegian computing center nr part simula 1961–1965 simula 67 1965–1968 simulation programming languages dahl nygaard first develop concepts class subclass allowing implicit information hiding inheritance dynamic object creation etc. important aspects oo paradigm object self-contained component data structure associated procedures methods software system combined form complete system object-oriented approach pervasive modern software development including widely used imperative programming languages java c++ received turing award work 2001 kristen nygaard received 2002 ieee john von neumann medal kristen nygaard named commander royal norwegian order st. olav 2000
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Programming language topics
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atari st basic atari st basic st basic first dialect basic produced atari st line computers bundled new sts early years st lifespan quickly became standard basic platform however many users disliked improved dialects basic quickly came replace atari commissioned metacomco write version basic would take advantage gem environment atari st based version already written digital research called dr-basic bundled dr cp/m-86 operating system result called st basic time st launched st basic bundled new sts port language called abasic ended supplied time amiga commodore quickly replaced microsoft-developed amigabasic user interface consisted four windows edit-window one could enter source code list-window entire source code could browsed command/debug-window instructions entered immediately executed output-window however windows could selected mouse became cumbersome st basic many bugs compute september 1987 reported one flaw described among worst basic bugs time typing codice_1 resulted similar commands codice_2 codice_3 crashed computer magazine described results last command bad crash get st without seeing machine rip free cables drag edge desk leap trash bin citing flaws codice_4 codice_5 equivalent magazine recommended avoid ing st basic serious programming regarding reports metacomco one bug away releasing long-delayed update language jokingly wondered whether atari one bug eliminate st basic one add relatively low quality st basic quickly opened market third-party basics st. fast basic gfa basic two first third-party basics released basics free program written one basics could listed run user basic however compilers run-time executables started appear basics produced executable code could run sts type-in programs became less fashionable longer need standard basic hisoft basic omikron basic stos basic appeared basics even started bundled new sts later years
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Programming language topics
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multi-factor authentication multi-factor authentication mfa authentication method computer user granted access successfully presenting two pieces evidence factors authentication mechanism knowledge something user user knows possession something user user inherence something user user two-factor authentication also known 2fa type subset multi-factor authentication method confirming users claimed identities using combination two different factors 1 something know 2 something 3 something good example two-factor authentication withdrawing money atm correct combination bank card something user possesses pin something user knows allows transaction carried two examples supplement user-controlled password one-time password otp code generated received authenticator e.g security token smartphone user possesses two-step verification two-step authentication method confirming user claimed identity utilizing something know password second factor something something example second step user repeating back something sent out-of-band mechanism second step might six digit number generated app common user authentication system use multiple authentication factors prove one identity based premise unauthorized actor unlikely able supply factors required access authentication attempt least one components missing supplied incorrectly user identity established sufficient certainty access asset e.g. building data protected multi-factor authentication remains blocked authentication factors multi-factor authentication scheme may include knowledge factors commonly used form authentication form user required prove knowledge secret order authenticate password secret word string characters used user authentication commonly used mechanism authentication many multi-factor authentication techniques rely password one factor authentication variations include longer ones formed multiple words passphrase shorter purely numeric personal identification number pin commonly used atm access traditionally passwords expected memorized many secret questions born poor examples knowledge factor may known wide group people able researched possession factors something user user used authentication centuries form key lock basic principle key embodies secret shared lock key principle underlies possession factor authentication computer systems security token example possession factor disconnected tokens connections client computer typically use built-in screen display generated authentication data manually typed user connected tokens devices physically connected computer used devices transmit data automatically number different types including card readers wireless tags usb tokens software token a.k.a soft token type two-factor authentication security device may used authorize use computer services software tokens stored general-purpose electronic device desktop computer laptop pda mobile phone duplicated contrast hardware tokens credentials stored dedicated hardware device therefore duplicated absent physical invasion device soft token may device user interacts typically x.509v3 certificate loaded onto device stored securely serve purpose factors associated user usually biometric methods including fingerprint face voice iris recognition behavioral biometrics keystroke dynamics also used increasingly fourth factor coming play involving physical location user hard wired corporate network user could allowed login utilizing pin code network entering code soft token well could required could seen acceptable standard access office controlled systems network admission control work similar ways level network access contingent specific network device connected wifi vs wired connectivity also allows user move offices dynamically receive level network access many multi-factor authentication vendors offer mobile phone-based authentication methods include push-based authentication qr code based authentication one-time password authentication event-based time-based sms-based verification sms-based verification suffers security concerns phones cloned apps run several phones cell-phone maintenance personnel read sms texts least cell phones compromised general meaning phone longer something user major drawback authentication including something user possesses user must carry around physical token usb stick bank card key similar practically times loss theft risks many organizations forbid carrying usb electronic devices premises owing malware data theft-risks important machines usb ports reason physical tokens usually scale typically requiring new token new account system procuring subsequently replacing tokens kind involves costs addition inherent conflicts unavoidable trade-offs usability security two-step authentication involving mobile phones smartphones provides alternative dedicated physical devices authenticate people use personal access codes device i.e something individual user knows plus one-time-valid dynamic passcode typically consisting 4 6 digits passcode sent mobile device sms generated one-time passcode-generator app cases advantage using mobile phone need additional dedicated token users tend carry mobile devices around times sms broadly-adopted multi-factor authentication method consumer-facing accounts notwithstanding popularity sms verification security advocates publicly criticized july 2016 united states nist draft guideline proposed deprecating form authentication year later nist reinstated sms verification valid authentication channel finalized guideline 2016 2017 respectively google apple started offering user two-step authentication push notification alternative method security mobile-delivered security tokens fully depends mobile operator operational security easily breached wiretapping sim cloning national security agencies advances research two-factor authentication mobile devices consider different methods second factor implemented posing hindrance user continued use improvements accuracy mobile hardware gps microphone gyro/acceleromoter ability use second factor authentication becoming trustworthy example recording ambient noise user location mobile device comparing recording ambient noise computer room user trying authenticate one able effective second factor authentication also reduces amount time effort needed complete process payment card industry pci data security standard requirement 8.3 requires use mfa remote network access originates outside network card data environment cde beginning pci-dss version 3.2 use mfa required administrative access cde even user within trusted network second payment services directive require strong customer authentication electronic payments european economic area september 14 2019 details authentication federal employees contractors usa defined homeland security presidential directive 12 hspd-12 existing authentication methodologies involve explained three types basic factors authentication methods depend one factor difficult compromise single-factor methods regulatory standards access federal government systems require use multi-factor authentication access sensitive resources example logging network devices perform administrative tasks accessing computer using privileged login nist special publication 800-63-3 discusses various forms two-factor authentication provides guidance using business processes requiring different levels assurance 2005 united states federal financial institutions examination council issued guidance financial institutions recommending financial institutions conduct risk-based assessments evaluate customer awareness programs develop security measures reliably authenticate customers remotely accessing online financial services officially recommending use authentication methods depend one factor specifically user knows determine user identity response publication numerous authentication vendors began improperly promoting challenge-questions secret images knowledge-based methods multi-factor authentication due resulting confusion widespread adoption methods august 15 2006 ffiec published supplemental guidelineswhich states definition true multi-factor authentication system must use distinct instances three factors authentication defined use multiple instances single factor according proponents multi-factor authentication could drastically reduce incidence online identity theft online fraud victim password would longer enough give thief permanent access information however many multi-factor authentication approaches remain vulnerable phishing man-in-the-browser man-in-the-middle attacks multi-factor authentication may ineffective modern threats like atm skimming phishing malware may 2017 o2 telefónica german mobile service provider confirmed cybercriminals exploited ss7 vulnerabilities bypass sms based two-step authentication unauthorized withdrawals users bank accounts criminals first infected account holder computers attempt steal bank account credentials phone numbers attackers purchased access fake telecom provider set-up redirect victim phone number handset controlled finally attackers logged victims online bank accounts requested money accounts withdrawn accounts owned criminals sms passcodes routed phone numbers controlled attackers criminals transferred money many multi-factor authentication products require users deploy client software make multi-factor authentication systems work vendors created separate installation packages network login web access credentials vpn connection credentials products may four five different software packages push client pc order make use token smart card translates four five packages version control performed four five packages check conflicts business applications access operated using web pages possible limit overheads outlined single application multi-factor authentication solutions virtual tokens hardware token products software must installed end users drawbacks multi-factor authentication keeping many approaches becoming widespread consumers difficulty keeping track hardware token usb plug many consumers technical skills needed install client-side software certificate generally multi-factor solutions require additional investment implementation costs maintenance hardware token-based systems proprietary vendors charge annual fee per user deployment hardware tokens logistically challenging hardware tokens may get damaged lost issuance tokens large industries banking even within large enterprises needs managed addition deployment costs multi-factor authentication often carries significant additional support costs 2008 survey 120 u.s. credit unions credit union journal reported support costs associated two-factor authentication report software certificates software toolbar approaches reported highest support costs research deployments multi-factor authentication schemes shown one elements tends impact adoption systems line business organization deploys multi-factor authentication system examples cited include u.s. federal government employs elaborate system physical tokens backed robust public key infrastructure well private banks tend prefer multi-factor authentication schemes customers involve accessible less expensive means identity verification app installed onto customer-owned smartphone despite variations exist among available systems organizations may choose multi-factor authentication system deployed within organization tends remain place users invariably acclimate presence use system embrace time normalized element daily process interaction relevant information system 2013 kim dotcom claimed invented two-factor authentication 2000 patent briefly threatened sue major web services however european patent office revoked patent light earlier 1998 us patent held several popular web services employ multi-factor authentication usually optional feature deactivated default many internet services among google amazon aws use open time-based one-time password algorithm totp support two-step authentication
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Computer security
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overlapped i/o overlapped i/o name used asynchronous i/o windows api introduced extension api windows nt utilizing overlapped i/o requires passing overlapped structure api functions normally block including readfile writefile winsock wsasend wsarecv requested operation initiated function call returns immediately completed os background caller may optionally specify win32 event handle raised operation completes alternatively program may receive notification event via i/o completion port preferred method receiving notification used symmetric multiprocessing environments handling i/o large number files sockets so-called overlapped api presents differences depending windows version used asynchronous i/o particularly useful sockets pipes unix linux implement posix asynchronous i/o api aio
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Operating systems
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name service switch name service switch nss facility unix-like operating systems provides variety sources common configuration databases name resolution mechanisms sources include local operating system files /etc/passwd /etc/group /etc/hosts domain name system dns network information service nis ldap system administrator usually configures operating system name services using file /etc/nsswitch.conf lists databases passwd shadow group one sources obtaining information examples sources files local files ldap lightweight directory access protocol nis network information service nisplus nis+ wins windows internet name service nsswitch.conf file line entries service consisting database name first field terminated colon list possible source databases mechanisms second field typical file might look like order services listed determines order nss attempt use services resolve queries specified database earlier unix-like systems notable exception ultrix either accessed configuration files hard-coded rules files databases access ultrix offered nearly identical functionality name service switch using configuration file /etc/svc.conf sun microsystems first developed nss solaris operating system subsequently programmers ported many operating systems including freebsd netbsd linux hp-ux irix aix
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Operating systems
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directdraw directdraw ddraw.dll deprecated api used part microsoft directx api directdraw used accelerate rendering 2d graphics applications directdraw also allows applications run fullscreen embedded window ms windows applications directdraw uses hardware acceleration available client computer directdraw allows direct access video memory hardware overlays hardware blitters page flipping video memory manager manipulate video memory ease taking full advantage blitting color decompression capabilities different types display adapters directdraw 2d api contains commands 2d rendering support 3d hardware acceleration programmer could use directdraw draw 3d graphics rendering would slow compared api direct3d support 3d hardware acceleration directdraw introduced windows mobile windows mobile 5.0 replacing graphics component gapi deprecated directdraw deprecated since version 7 directx version 8.0 directdraw merged new package called directx graphics extended direct3d directdraw api additions directdraw still used programmers must use older directx interfaces directx 7 release june 2010 directx sdk package directdraw header file library longer included concurrent deprecation directdraw deterioration windows compatibility old games relied old api command conquer warcraft 2 theme hospital among affected newer windows versions games refuse run 32-bit bit depth others showing black screen glitching switched re-implementation ddraw result vital many communities still hosting games commonly used replacements include
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Operating systems
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microsoft forefront unified access gateway microsoft forefront unified access gateway uag software suite provides secure remote access corporate networks remote employees business partners services include reverse proxy virtual private network vpn directaccess remote desktop services uag released 2010 successor microsoft intelligent application gateway iag released 2007 uag part microsoft forefront offering microsoft discontinued product 2014 although web application proxy feature windows server 2012 r2 later offers functionalities web application proxy direct feature-for-feature replacement companies like portsys f5 offer direct migration paths uag deployments unified access gateway originally developed startup company named whale communications rosh haayin israel one challenges tried solve 1990s develop remote access solution based vpn mechanism without direct network access remote client corporate network type solution specifically required israeli military government meet national information security standards technology developed called air gap communication external network internal network managed two separate 1u rack-mount servers linked together memory bank accessed scsi interface 18 may 2006 microsoft announced would acquiring whale communications microsoft completed acquisition 26 july 2006 following acquisition product renamed microsoft intelligent application gateway server 2007 version scsi-based air gap dropped product unified single-server appliance instead using air gap security barrier iag used microsoft isa server firewall product iag offered public pre-installed appliance celestix networks ivo networks portsys nappliance 2009 release service pack 2 iag product also offered directly public microsoft form virtual appliance pre-installed vhd could run hyper-v vmware workstation april 2008 microsoft announced next generation iag named forefront unified access gateway product released 24 december 2009 service pack 1 product released 3 december 2010 update 1 service pack 1 released 17 october 2011 service pack 2 product released 6 august 2011 service pack 3 released 19 february 2013 service pack 4 released 27 november 2013 17 december microsoft announced microsoft deliver future full version releases forefront uag product removed price lists 1 july 2014 microsoft uag provides secure socket layer ssl virtual private network vpn web application firewall endpoint security management compliance security enable access control authorization content inspection wide variety line-of-business applications included customized granular access policy security capabilities microsoft exchange server 2003 2007 2010 microsoft sharepoint portal server 2003 2007 2010 microsoft terminal services citrix presentation server product highly customizable almost application published uag box uag server able work many authentication vendors mi-token rsa security onespan gridsure swivel activcard aladdin also works numerous authentication systems protocols active directory radius ldap ntlm lotus domino pki tacacs+ possible customizations include single-sign-on sso well look-and-feel dynamic customization current release uag update 2 product also offers support many third-party systems linux macintosh iphone product also supports mozilla firefox uag performs particularly well providing portal web applications web-based email intranets also provides full ssl vpn network access using either activex using internet explorer java components using firefox opera non windows client red hat mac os components also perform end-point compliance checks allowing access test attributes pc domain name antivirus definitions date running processes inclusion directaccess uag big influence success directaccess provides seamless vpn-like integration high-demand many organizations directaccess part windows uag provides user-friendly configuration interface making easier configure administrators uag also adds two additional components dns64 nat64 make deploying directaccess existing network easier without need deploy ipv6 product sold appliance form vendors ivo networks portsys celestix networks nappliance also offered installable dvd product installed windows server 2008 r2
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Computer security
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traceroute computing codice_1 codice_2 computer network diagnostic commands displaying route path measuring transit delays packets across internet protocol ip network history route recorded round-trip times packets received successive host remote node route path sum mean times hop measure total time spent establish connection traceroute proceeds unless three sent packets lost twice connection lost route evaluated ping hand computes final round-trip times destination point internet protocol version 6 ipv6 tool sometimes name traceroute6 tracert6 command codice_1 available many modern operating systems unix-like systems freebsd macos linux available command line tool traceroute also graphically accessible macos within network utilities suite microsoft windows reactos provide program named codice_2 performs route-tracing function windows nt-based operating systems also provide pathping similar functionality reactos version developed ged murphy licensed gpl unix-like operating systems traceroute sends default sequence user datagram protocol udp packets destination port numbers ranging 33434 33534 implementations traceroute shipped linux freebsd netbsd openbsd dragonfly bsd macos include option use icmp echo request packets -i arbitrary protocol -p udp tcp using tcp syn packets icmp windows tracert sends icmp echo request packets rather udp packets traceroute sends default time-to-live ttl value also known hop limit used determining intermediate routers traversed towards destination traceroute sends packets ttl values gradually increase packet packet starting ttl value one routers decrement ttl values packets one routing discard packets whose ttl value reached zero returning icmp error message icmp time exceeded first set packets first router receives packet decrements ttl value drops packet ttl value zero router sends icmp time exceeded message back source next set packets given ttl value two first router forwards packets second router drops replies icmp time exceeded proceeding way traceroute uses returned icmp time exceeded messages build list routers packets traverse destination reached returns icmp destination unreachable message udp packets used icmp echo reply message icmp echo messages used timestamp values returned router along path delay latency values typically measured milliseconds packet sender expects reply within specified number seconds packet acknowledged within expected interval asterisk displayed internet protocol require packets take route towards particular destination thus hosts listed might hosts packets traversed host hop n reply hop skipped output network firewall operates windows unix-like systems one protocol must enabled inbound firewall traceroute work receive replies traceroute implementations use tcp packets tcptraceroute layer four traceroute pathping utility introduced windows nt combines ping traceroute functionality mtr enhanced version icmp traceroute available unix-like windows systems various implementations traceroute rely icmp time exceeded type 11 packets sent source linux tracepath utility similar traceroute primary difference requiring superuser privileges cisco implementation traceroute also uses sequence udp datagrams incrementing ttl values invalid port number remote host default udp port 33434 used extended version command known extended traceroute command change destination port number used udp probe messages implementations include least options specify number queries send per hop time wait response hop limit port use invoking traceroute specified options displays list available options man traceroute presents details including displayed error flags simple example linux example selected options wait three seconds instead five send one query hop instead three limit maximum number hops 16 giving instead 30 example.com final host help identify incorrect routing table definitions firewalls may blocking icmp traffic high port udp unix ping site note firewall may permit icmp packets permit packets protocols traceroute also used penetration testers gather information network infrastructure ip ranges around given host also used downloading data multiple mirrors available piece data one trace mirror get good idea mirror would fastest use traceroute manual page states original traceroute program written van jacobson 1987 suggestion steve deering particularly cogent suggestions fixes c. philip wood tim seaver ken adelman author ping program mike muuss states website traceroute written using kernel icmp support earlier coded enable raw icmp sockets first wrote ping program traceroute limitations well known taken account using tool example traceroute discover paths router level interface level another limitation appears routers respond probes routers limit icmp responses presence traffic load balancing traceroute may indicate path actually exist minimize problem traceroute modification called paris-traceroute maintains flow identifier probes avoid load balancing
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Computer security
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time live time live ttl hop limit mechanism limits lifespan lifetime data computer network ttl may implemented counter timestamp attached embedded data prescribed event count timespan elapsed data discarded revalidated computer networking ttl prevents data packet circulating indefinitely computing applications ttl commonly used improve performance manage caching data internet protocol ttl 8-bit field ipv4 header ttl 9th octet 20 ipv6 header 8th octet 40 maximum ttl value 255 maximum value single octet recommended initial value 64 time-to-live value thought upper bound time ip datagram exist internet system ttl field set sender datagram reduced every router route destination ttl field reaches zero datagram arrives destination datagram discarded internet control message protocol icmp error datagram 11 time exceeded sent back sender purpose ttl field avoid situation undeliverable datagram keeps circulating internet system system eventually becoming swamped immortals theory ipv4 time live measured seconds although every host passes datagram must reduce ttl least one unit practice ttl field reduced one every hop reflect practice field renamed hop limit ipv6 ttls also occur domain name system dns set authoritative name server particular resource record caching recursive nameserver queries authoritative nameserver resource record cache record time seconds specified ttl stub resolver queries caching nameserver record ttl expired caching server simply reply already cached resource record rather retrieve authoritative nameserver ttl nxdomain non-existent domain responses set minimum minimum field soa record ttl soa indicates long resolver may cache negative answer shorter ttls cause heavier loads authoritative name server useful changing address critical services like web servers mx records therefore often lowered dns administrator prior service moved order reduce possible disruptions units used seconds older common ttl value dns 86400 seconds 24 hours ttl value 86400 would mean dns record changed authoritative nameserver dns servers around world could still showing old value cache 24 hours change newer dns methods part disaster recovery dr system may records deliberately set extremely low ttl example 300-second ttl would help key records expire 5 minutes help ensure records flushed quickly worldwide gives administrators ability edit update records timely manner ttl values per record setting value specific records sometimes honored automatically standard dns systems worldwide however problem persists caching dns nameservers set ttls regardless authoritative records thus guaranteed downstream dns servers new records ttl expired time live may also expressed date time record expires codice_1 header http responses codice_2 header field requests responses codice_3 field http cookies express time-to-live way
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Internet protocols
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trash computing computing trash also known recycle bin microsoft windows names operating systems temporary storage files deleted file manager user yet permanently erased file system typically recycle bin presented special file directory user whether actually single directory depends implementation allowing user browse deleted removed files undelete deleted mistake delete permanently either one one empty trash function within trash folder record kept file and/or directory original location certain operating systems files must moved trash accessed whether files deleted program go recycle bin depends level integration particular desktop environment function low-level utilities usually bypass layer entirely delete files immediately program includes file manager functionality may may send files recycle bin may allow user choose options small icon waste container deleting files implemented development apple lisa user interface 1982 called “ wastebasket. ” concept carried apple macintosh “ trash ” except pre-os 9 “ international english ” localization retained “ wastebasket. ” apple inc. sued prevent software companies offering graphical user interfaces similar apple lost claims courts agreed apple trash icon original protected copyright non-apple software may use metaphors file deletion recycle bin smart eraser shredder early versions macintosh finder trash contents listed volatile memory files moved trash would appear finder session ended would automatically erased system 7 released trash became folder retained contents user chose empty trash microsoft first implemented trash concept ms-dos 6 name delete sentry file deleted moved hidden sentry folder root drive microsoft introduced current trash system recycle bin windows 95 area store review files folders prior deletion version original location record file stored folder n't allow subdirectories folder deleted containing files moved bin mixed deleted files directory structure restored batch files undeleted current revised recycle bin allows subdirectory trees exist within folders moved recycle bin functionality usually integrated desktop environment file manager examples include implementations may contain shredding functionality counter data remanence kde gnome xfce implementations comply freedesktop.org trash specification ensuring applications written specification mind interoperable trash implementation although various linux desktop environments gnome kde xfce provide trash mechanism traditionally simple way trash something command line interface third-party applications trash-cli provide commands command-line use trash compatible freedesktop.org trash specification macos file deleted finder moved .trashes folder viewing device available space space occupied deleted files shown occupied macos sierra user turn option trash delete 30 days microsoft recycle bin implemented special folder columns like date deleted original location typically files deleted via file explorer necessarily windows graphical interfaces file selection dialogs put recycle bin files deleted via command prompt permanently deleted default files deleted via operating system apis applications windows explorer operating system apis however allow applications recycle files rather delete previous windows operating systems ms-dos undeletion way recover accidentally intentionally deleted files standard recycle bin stores files deleted hard drives removable media memory cards thumb drives floppy disks store files deleted network drives methods make work network paths however recycle bin setting configure amount deleted files store free disk space allocated actually used files deleted folders stored recycle bin versions windows prior windows vista default configuration recycle bin global setting drives hold 10 total capacity host hard drive volume store deleted files example volume capacity 20 gigabytes recycle bin hold 2 gigabytes deleted files changed anywhere 0 100 drive space allowed exceed 3.99gb space even user-indicated drive space larger 3.99gb recycle bin fills maximum capacity oldest files deleted order accommodate newly deleted files file large recycle bin user prompted immediately permanently delete file instead 3.99gb limit apply windows vista later windows versions actual location recycle bin depends type operating system file system older fat file systems typically windows 98 prior located drive \recycled ntfs filesystem windows 2000 xp nt drive \recycler windows vista windows 7 drive recycle.bin folder recycle bin accessed desktop windows explorer typing shell recyclebinfolder run dialog box icon shown default windows xp desktop accessed desktop recycle bin options information different physical recycle bin folders seen partition windows explorer windows xp onwards ntfs different users see contents recycle bins prior windows vista file recycle bin stored physical location renamed original drive letter file original extension hidden file called info2 info windows 95 without windows desktop update stores file original path original name binary format since windows vista meta information file saved number original extension original file renamed r number original extension user views recycle bin files displayed original names file restored recycle bin returned original directory name windows explorer files moved recycle bin number ways possible bypass recycle bin directly delete file holding shift key performing action would normally send file trash apple ’ macos long allowed dragging disk icon trash method unmounting and/or physically ejecting disk place disk trash folder erase disk macos trash icon temporarily changes eject disconnect symbol whenever storage volumes dragged gnome human interface guidelines cite behavior example discouraged metaphor
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Computer file systems
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optimus ui optimus ui front-end touch interface developed lg electronics partners featuring full touch user interface sometimes incorrectly identified operating system optimus ui used internally lg sophisticated feature phones tablet computers available licensing external parties latest version optimus ui 4.1.2 released optimus k ii optimus neo 3 features refined user interface compared previous version 4.1.1 would include voice shutter quick memo optimus ui used devices based android
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Operating systems
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