Ukusethwa kokuxhuma kwe-TCP
Lapho sidlulisa amehlo kwi-web, thumela i-imeyili, noma udlale umdlalo we-inthanethi, imvamisa asicabangi ngokuxhumeka kwenethiwekhi okuyinkimbinkimbi ngemuva kwaso. Kodwa-ke, yilezi zinyathelo ezibonakala zincane eziqinisekisa ukuxhumana okuzinzile phakathi kwethu neseva. Enye yezinyathelo ezibaluleke kakhulu ukusetha kokuxhuma kwe-TCP, kanye nomgogodla walokhu yimbandla enezindlela ezintathu.
Lo mbhalo uzoxoxa ngomgomo, inqubo kanye nokubaluleka kokuxhawula kwezindlela ezintathu ngokuningiliziwe. Isinyathelo ngesinyathelo, sizochaza ukuthi kungani ukwakheka kwezindlela ezintathu kudingeka, ukuthi kuqinisekisa kanjani ukuxhuma nokuthembela, nokuthi kubaluleke kangakanani ukudluliswa kwedatha. Ngokuqonda okujulile kwesandla esinezindlela ezintathu, sizothola ukuqonda okungcono ngezinqubo ezingaphansi zokuxhumana kwenethiwekhi kanye nombono ocacile wokuthembeka kokuxhumana kwe-TCP.
Inqubo ye-TCP ye-Tandshake enezindlela ezintathu kanye nezinguquko zombuso
I-TCP i-protocol yokuxhumeka ethambekele ekuxhumekeni, edinga ukuxhunywa kwayo ngaphambi kokudluliselwa kwedatha. Le nqubo yokusungulwa kokusungulwa yenziwa nge-pantshake enezindlela ezintathu.
Ake sibheke eduze amaphakethe we-TCP athunyelwe ekuxhumekeni ngakunye.
Ekuqaleni, bobabili iklayenti neseva kuvaliwe. Okokuqala, iseva ibala ngenkuthalo ethekwini futhi isesimweni sokulalela, okusho ukuthi iseva kumele liqale. Okulandelayo, iklayenti lilungele ukuqala ukufinyelela ikhasi lewebhu.Idinga ukusungula ukuxhumana neseva. Ifomethi yephakethe lokuxhumana lokuqala limi ngokulandelayo:
Lapho iklayenti liqala ukuxhumeka, ikhiqiza inombolo yokulandelana kokuqala okungahleliwe (iklayenti_isn) futhi liyibeka enkambu "yenombolo yokulandelana" yekhanda le-TCP. Ngasikhathi sinye, iklayenti libeka isikhundla sefulegi lokunye uku-1 ukukhombisa ukuthi iphakethe eliphumayo liyiphakethe elihlangene. Iklayenti libonisa ukuthi lifisa ukusungula ukuxhumana neseva ngokuthumela iphakethe lokunye lokuqala kwiseva. Le phakethe ayiqukethe idatha yesendlalelo sohlelo lokusebenza (okungukuthi, idatha ethunyelwe). Ngalesi sikhathi, isimo seklayenti simakwe njengabathunyelwa.
Lapho iseva ithola iphakethe elivela kwiklayenti, liqala ngezikhathi ezithile inombolo yalo ye-serial (iseva_isn) bese ibeka lelo nani endaweni ethi "Inombolo Yenombolo" ye-TCP Header. Okulandelayo, iseva ingena kwiklayenti_isn + 1 kwinkambu "yokuvuma" bese isetha zombili izingcezu zokunye futhi ze-ACK kuya ku-1. Ekugcineni, i-server ithumela i-packet kwi-appliels (futhi ayikho idatha yeseva ukuthumela). Ngalesi sikhathi, iseva isesimweni se-Syn-RCVD.
Lapho iklayenti lithola iphakethe elivela kuseva, lidinga ukwenza lokhu okulandelayo ukuphendula iphakethe lokuphendula lokugcina: Okokuqala, iklayenti libeka i-ack bird ye-TCP ye-TCP yephakethe lempendulo ku-1; Okwesibili, iklayenti lingena kwiseva yenani le-server_isn + 1 ku "Qinisekisa Inombolo Yenombolo"; Ekugcineni, iklayenti lithumela iphakethe kwiseva. Le phakethe ingaphatha idatha kusuka kwiklayenti kwiseva. Lapho usuqede le misebenzi, iklayenti lizongena esimweni esisunguliwe.
Lapho iseva ithola iphakethe lempendulo kusuka kwiklayenti, libuye lishintshele esimweni esisunguliwe.
Njengoba ubona kusuka kule nqubo engenhla, lapho wenza ukuphathwa ngesandla emithathu, ukuphathwa kwesithathu kuvunyelwe ukuphatha idatha, kepha ukugadwa kokuqala okubili akunjalo. Lo ngumbuzo ovame ukubuzwa ezingxoxweni. Lapho nje ukuphathwa ngesandla kwezindlela ezintathu sekuqediwe, zombili izinhlangothi zingena ezweni elisunguliwe, okukhombisa ukuthi ukuxhumana kusungulwe ngempumelelo, lapho iklayenti neseva ingaqala ukuthumela idatha komunye nomunye.
Kungani Ukuphathwa Kwezandla Kathathu? Hhayi kabili, amahlandla amane?
Impendulo evamile ithi, "Ngoba ukuphathwa ngesandla ezintathu kuqinisekisa amandla okwamukela nokuthumela." Le mpendulo ilungile, kepha yisizathu kuphela, ayibeki phambili isizathu esiyinhloko. Kokulandelayo, ngizohlaziya izizathu zokubambana kathathu ezivela ezicini ezintathu ukujulisa ukuqonda kwethu kwalolu daba.
Ukubambana ngezindlela ezintathu kungakugwema ngempumelelo ukuqaliswa kokuxhumeka okuphindaphindwayo ngokomlando (isizathu esiyinhloko)
I-wandshat enezindlela ezintathu iqinisekisa ukuthi amaqembu womabili athole inombolo enokwethenjelwa yokuqala yokulandelana.
Ukubambana ngezindlela ezintathu kugwema ukuchitha izinsizakusebenza.
Isizathu 1: Gwema ukujoyina okuphindwe kabili ngokomlando
Ngamafuphi, isizathu esiyinhloko sokubambana ngezindlela ezintathu ukugwema ukudideka okubangelwa ukuqaliswa kokuxhumeka okudala okuphindwe kabili. Emvelweni eyinkimbinkimbi yenethiwekhi, ukuhanjiswa kwamaphakethe wedatha akuhlali kuthunyelwe kumgcini wendawo lapho kuhambisana nesikhathi esibekiwe, futhi amaphakethe wedatha amadala angafika endaweni yokuhamba lapho uya khona ngenxa yokuxinana kwenethiwekhi nezinye izizathu. Ukugwema lokhu, i-TCP isebenzisa ukuphathwa ngesandla ezintathu ukusungula ukuxhumana.
Lapho iklayenti lithumela amaphakethe wokuxhumanisa amaningi wokuhlanza ngokulandelana, ezimweni ezifana nokuxinana kwenethiwekhi, okulandelayo kungenzeka:
1- Amaphakethe amadala ahlanganisiwe afika kwiseva ngaphambi kwamaphakethe okunye ama-syn.
I-2- Iseva izophendula iphakethe le-Syn + ACK liye kwiklayenti ngemuva kokuthola iphakethe elidala lokunye.
3- Lapho iklayenti lithola iphakethe le-S synble + ack, linquma ukuthi ukuxhumana kungukuxhumana okungokomlando (inombolo yokulandelana iphelelwa yisikhathi noma isikhathi sokuphelelwa yisikhathi) ngokuya ngomongo wayo, bese uthumela iphakethe le-rst kwiseva ukukhipha uxhumano.
Ngokuxhumeka okwenziwe ngesandla okubili, ayikho indlela yokuthola ukuthi ngabe ukuxhumana kwamanje kungukuxhumana okungokomlando. I-Handshake enezindlela ezintathu ivumela iklayenti ukuthi linqume ukuthi ukuxhumana kwamanje kungukuxhumana okungokomlando okusekelwe kumongo lapho kulungele ukuthumela iphakethe lesithathu:
1- Uma kungukuxhumana okungokomlando (Inombolo yokulandelana iphelelwa yisikhathi noma i-Timeout), iphakethe elithunyelwe nge-packet yesithathu yiphakethe le-RST lokukhipha uxhumano lomlando.
2- Uma kungukuxhumana okungokomlando, iphakethe elithunyelwe okwesithathu yipakethe le-ack, futhi amaqembu amabili axhumana aqala ngokuphumelelayo nokuxhumana.
Ngakho-ke, isizathu esiyinhloko sokuthi i-TCP isebenzisa ukuphathwa kwezindlela ezintathu ukuthi iqala ukuxhumana ukuvikela ukuxhumana komlando.
Isizathu 2: Ukuvumelanisa izinombolo zokulandelana kokuqala zawo womabili amaqembu
Zombili izinhlangothi zephrothokholi ye-TCP kumele zilondoloze inombolo yokulandelana, okuyinto ebalulekile ukuqinisekisa ukudluliswa okuthembekile. Izinombolo zokulandelana zidlala indima ebalulekile ekuxhumekeni kwe-TCP.Lakha okulandelayo:
Otholayo angasusa idatha eyimpinda futhi aqinisekise ukunemba kwemininingwane.
Otholayo angathola amaphakethe ngokulandelana kwenombolo yokulandelana ukuze aqinisekise ukuthembeka kwedatha.
● Inombolo yokulandelana ingakhomba iphakethe ledatha elitholwe yilinye iqembu, inika amandla ukuhanjiswa kwedatha okuthembekile.
Ngakho-ke, lapho kusungulwa ukuxhumana kwe-TCP, iklayenti lithumela amaphakethe oku-syn ngenombolo yokuqala yokulandelana futhi idinga ukuthi iseva iphendule ngepakethe le-ACK elibonisa ukwamukelwa okuphumelelayo kwephakethe lokunyelwa kwamakhasimende. Ngemuva kwalokho, iseva ithumela iphakethe elihambisana nenombolo yokulandelana kokuqala kwiklayenti futhi lilindela iklayenti ukuthi liphendule, kanye nakuko konke ukulandelana kokulandelana kuyavumelaniswa ngokuthembekile.
Yize ukuphathwa ngesandla ezine kungenzeka futhi ukuvumelanisa ngokuthembekile izinombolo zokulandelana kokuqala zawo womabili amaqembu, izinyathelo zesibili nezesithathu zingahlanganiswa zibe yisinyathelo esisodwa, okuholele ekubambeni ngesandla ezintathu. Kodwa-ke, ukuboshwa okubili kuqinisekisa kuphela ukuthi inombolo yokuqala yokulandelana kweqembu elilodwa itholwe ngempumelelo yilinye iqembu, kepha asikho isiqinisekiso sokulandelana kokulandelana kwawo womabili amaqembu angaqinisekiswa. Ngakho-ke, ukuphathwa ngesandla kwezindlela ezintathu kuyisinqumo esihle kunazo zonke sokuthatha ukuze uqinisekise ukuqina kanye nokwethenjwa kokuxhunyaniswa kwe-TCP.
Isizathu 3: Gwema ukuchitha izinsizakusebenza
Uma kukhona "ukuphakanyiswa ngesandla ezimbili kuphela, lapho isicelo esivumelanayo seklayenti sivinjelwe kunethiwekhi, iklayenti alikwazi ukuthola iphakethe le-ACK elithunyelwe yiseva, ngakho-ke ukuvumelanisa kuzoba nokucasulwa. Kodwa-ke, njengoba kungekho ukuphathwa kwesithathu, iseva ayikwazi ukubona ukuthi iklayenti lithole yini ukuvuma kwe-ACK ukuthola ukuxhumana. Ngakho-ke, iseva ingasungula kuphela ukuxhumana ngemuva kokuthola isicelo ngasinye sokwenza. Lokhu kuholela kokulandelayo:
Ukungcola Kwezinsizakusebenza: Uma uhlelo lokusebenza lweklayenti luvinjelwe, okuholela ekudluliseleni okuphindaphindiwe kwamaphakethe amaningi wokunye, iseva izosungula ukuxhumana okuningi okungafuneki ngemuva kokuthola isicelo. Lokhu kuholela ekungcoleni okungadingekile kwemithombo yeseva.
Ukugcinwa komlayezo: Ngenxa yokuntuleka kwesandla okwesithathu, iseva ayinayo indlela yokwazi ukuthi iklayenti lithole kahle ukuvuma kwe-ACK ukuthola ukuxhumana. Ngenxa yalokhu, uma imilayezo ibambeke kunethiwekhi, iklayenti lizogcina ukuthumela izicelo eziphindaphindwayo kaningi, okwenza iseva iphinde isungule ukuxhumana okusha. Lokhu kuzokhuphula ukugcwala kwenethiwekhi nokubambezeleka nokubabaza ngokungafanele ukusebenza kwenethiwekhi yonke.
Ngakho-ke, ukuze kuqinisekiswe ukuqina kanye nokwethenjwa kokuxhumeka kwenethiwekhi, i-TCP isebenzisa ukuphakanyiswa kwezindlela ezintathu ukusungula ukuxhumana ukuze kugwemeke kwenzeka kwalezi zinkinga.
Ukubeka kafushane
Le khasiBroker ye-Network PacketUkusungulwa kokuxhumeka kwe-TCP kwenziwa nge-handshake enezindlela ezintathu. Ngesikhathi sokubambana ngezindlela ezintathu, iklayenti liqala ukuthumela iphakethe ngefulegi elivumelanayo kwiseva, libonisa ukuthi lifuna ukusungula ukuxhumana. Ngemuva kokuthola isicelo kusuka kwiklayenti, iseva iphendula ngepakethe elinamafulegi okuvumelanayo nase-ACK kwiklayenti, elibonisa ukuthi isicelo sokuxhuma samukelwa, futhi sithumela inombolo yaso yokuqala yokulandelana. Ekugcineni, iklayenti liphendula ngefulegi le-ACK kwiseva ukukhombisa ukuthi ukuxhumana kusungulwe ngempumelelo. Ngakho-ke, la maqembu womabili asesimweni esisunguliwe futhi angaqala ukuthumela idatha komunye nomunye.
Ngokuvamile, inqubo enezindlela ezintathu zokusungulwa kokuxhumeka kwe-TCP yenzelwe ukuqinisekisa ukuqina kokuxhuma nokwethenjwa, gwema ukudideka kanye nokuchitha izinsiza ngokuxhunyaniswa komlando, futhi uqinisekise ukuthi amaqembu womabili ayakwazi ukuthola nokuthumela idatha.
Isikhathi sePosi: Jan-08-2025
