Ukusethwa kokuxhuma kwe-TCP
Uma siphequlula iwebhu, sithumela i-imeyili, noma sidlala igeyimu eku-inthanethi, ngokuvamile asicabangi ngoxhumo lwenethiwekhi oluyinkimbinkimbi ngemuva kwayo. Nokho, yilezi zinyathelo ezibonakala zizincane eziqinisekisa ukuxhumana okuzinzile phakathi kwethu neseva. Esinye sezinyathelo ezibaluleke kakhulu ukusethwa kokuxhumana kwe-TCP, futhi umnyombo walokhu ukuxhawula izindlela ezintathu.
Lesi sihloko sizoxoxa ngesimiso, inqubo kanye nokubaluleka kokuxhawula ngezindlela ezintathu ngokuningiliziwe. Isinyathelo ngesinyathelo, sizochaza ukuthi kungani ukuxhawula kwezindlela ezintathu kuyadingeka, ukuthi kuqinisekisa kanjani ukuzinza nokuthembeka kokuxhumana, nokuthi kubaluleke kangakanani ekudluliselweni kwedatha. Ngokuqonda okujulile kokuxhawula izindlela ezintathu, sizothola ukuqonda okungcono kwezindlela eziyisisekelo zokuxhumana kwenethiwekhi kanye nombono ocacile wokuthembeka kokuxhumana kwe-TCP.
Inqubo Yezindlela Ezintathu Zokuxhawula I-TCP kanye Nezinguquko Zesifunda
I-TCP iyiphrothokholi yezokuthutha egxile ekuxhumekeni, edinga ukusungulwa kokuxhumana ngaphambi kokudluliswa kwedatha. Le nqubo yokusungulwa kokuxhumana yenziwa ngokuxhawulana ngezindlela ezintathu.
Ake sibhekisise amaphakethe e-TCP athunyelwa ekuxhumekeni ngakunye.
Ekuqaleni, kokubili iklayenti neseva KUVALIWE. Okokuqala, iseva ilalela ngenkuthalo embobeni futhi isesimweni esithi LISTEN, okusho ukuthi iseva kufanele iqalwe. Okulandelayo, iklayenti selilungele ukuqala ukufinyelela ikhasi lewebhu.Idinga ukusungula uxhumano neseva. Ifomethi yephakethe lokuqala lokuxhuma imi kanje:
Uma iklayenti liqalisa uxhumano, likhiqiza inombolo yokuqala yokulandelana engahleliwe (client_isn) futhi liyibeke endaweni ethi "Inombolo yokulandelana" yesihloko se-TCP. Ngesikhathi esifanayo, iklayenti lisetha indawo yefulegi ye-SYN ku-1 ukukhombisa ukuthi iphakethe eliphumayo liyiphakethe le-SYN. Iklayenti libonisa ukuthi lifisa ukusungula uxhumano neseva ngokuthumela iphakethe lokuqala le-SYN kuseva. Leli phakethe alinayo idatha yesendlalelo sohlelo lokusebenza (okungukuthi, idatha ethunyelwe). Kuleli qophelo, isimo seklayenti simakwe njengokuthi SYN-SENT.
Uma iseva ithola iphakethe le-SYN kuklayenti, iqala ngokungahleliwe inombolo yayo yomkhiqizo (server_isn) bese ibeka leyo nombolo kunkambu ethi "Inombolo yomkhiqizo" yesihloko se-TCP. Okulandelayo, iseva ifaka iklayenti_isn + 1 kunkambu ethi "Inombolo yokuvuma" bese isetha kokubili amabhithi e-SYN kanye ne-ACK ku-1. Ekugcineni, iseva ithumela iphakethe kuklayenti, elingenayo idatha yesendlalelo sohlelo lokusebenza (futhi ayikho idatha yeseva. ukuthumela). Ngalesi sikhathi, iseva isesimweni se-SYN-RCVD.
Uma iklayenti ithola iphakethe kusuka kuseva, idinga ukwenza ukulungiselelwa okulandelayo ukuze iphendule iphakethe lokugcina lokuphendula: Okokuqala, iklayenti libeka i-ACK bit ye-TCP unhlokweni wephakethe lokuphendula ku-1; Okwesibili, iklayenti lifaka inani le-server_isn + 1 endaweni ethi "Qinisekisa inombolo yempendulo"; Ekugcineni, iklayenti lithumela iphakethe kuseva. Leli phakethe lingaphatha idatha isuka kuklayenti iye kuseva. Ngemva kokuqeda le misebenzi, iklayenti lizongena kusimo ESIMISWAYO.
Uma iseva ithola iphakethe lempendulo kuklayenti, iphinde ishintshele kusimo ESISIKIWE.
Njengoba ubona kule nqubo engenhla, lapho wenza ukuxhawula ngezindlela ezintathu, ukuxhawula kwesithathu kuvunyelwe ukuthwala idatha, kodwa ukuxhawula okubili kokuqala akunjalo. Lona umbuzo ovame ukubuzwa ezingxoxweni. Uma ukuxhawula kwezindlela ezintathu sekuqediwe, zombili izinhlangothi zingena kusimo ESImisiwe, okubonisa ukuthi uxhumano lusungulwe ngempumelelo, ngaleso sikhathi iklayenti neseva bangaqala ukuthumela idatha komunye nomunye.
Kungani kuxhawulana kathathu? Hhayi kabili, kane?
Impendulo evamile ithi, "Ngoba ukuxhawula izindlela ezintathu kuqinisekisa ikhono lokwamukela nokuthumela." Le mpendulo ilungile, kodwa yisizathu esingaphezulu kuphela, asibeki isizathu esiyinhloko. Ngokulandelayo, ngizohlaziya izizathu zokuxhawulana kathathu ezicini ezintathu ukuze sijulise ukuqonda kwethu lolu daba.
Ukuxhawula izindlela ezintathu kungagwema ngempumelelo ukuqaliswa kokuxhumana okuphindaphindiwe ngokomlando (isizathu esikhulu)
Ukuxhawula izindlela ezintathu kuqinisekisa ukuthi zombili izinhlangothi zithole inombolo ethembekile yokulandelana kwasekuqaleni.
Ukuxhawula izindlela ezintathu kugwema ukumosha izinsiza.
Isizathu 1: Gwema Ukujoyina Okuphindayo Komlando
Kafushane, isizathu esiyinhloko sokuxhawula izindlela ezintathu ukugwema ukudideka okubangelwa ukuqaliswa kokuxhumeka okuyimpinda endala. Esimeni senethiwekhi esiyinkimbinkimbi, ukudluliswa kwamaphakethe edatha akuhlali kuthunyelwa kumsingathi wendawo ngokuvumelana nesikhathi esishiwo, futhi amaphakethe edatha amadala angase afike kumsingathi wendawo kuqala ngenxa yokuminyana kwenethiwekhi nezinye izizathu. Ukugwema lokhu, i-TCP isebenzisa ukuxhawula izindlela ezintathu ukuze isungule uxhumano.
Uma iklayenti lithumela amaphakethe amaningi okusungulwa koxhumano lwe-SYN ngokulandelana, ezimeni ezifana nokuminyana kwenethiwekhi, okulandelayo kungenzeka:
1- Amaphakethe e-SYN amadala afika kuseva ngaphambi kwamaphakethe e-SYN akamuva.
2- Iseva izophendula iphakethe le-SYN + ACK kuklayenti ngemva kokuthola iphakethe le-SYN endala.
3- Lapho iklayenti lithola iphakethe le-SYN + ACK, linquma ukuthi ukuxhumana kuwukuxhumana okungokomlando (inombolo yokulandelana iphelelwe yisikhathi noma iphelelwe yisikhathi) ngokuya komongo wayo, bese ithumela iphakethe le-RST kuseva ukuze inqamule uxhumano.
Ngokuxhumeka kokuxhawula okubili, ayikho indlela yokunquma ukuthi uxhumano lwamanje luwukuxhumana okungokomlando. Ukuxhawula izindlela ezintathu kuvumela iklayenti ukuthi linqume ukuthi uxhumano lwamanje luwukuxhumana okungokomlando okususelwe kumongo uma selilungele ukuthumela iphakethe lesithathu:
1- Uma kuwukuxhumana okungokomlando (inombolo yokulandelana iphelelwe yisikhathi noma isikhathi siphelile), iphakethe elithunyelwe ukuxhawulana kwesithathu liyiphakethe le-RST ukuze kunqandwe ukuxhumana okungokomlando.
2- Uma kungekona ukuxhumana okungokomlando, iphakethe elithunyelwe okwesithathu liyiphakethe le-ACK, futhi izinhlangothi ezimbili ezixhumanayo zilusungula ngempumelelo uxhumano.
Ngakho-ke, isizathu esiyinhloko sokuthi i-TCP isebenzisa ukuxhawula kwezindlela ezintathu ukuthi iqalisa uxhumano ukuvimbela ukuxhumana okungokomlando.
Isizathu sesi-2: Ukuvumelanisa izinombolo zokuqala zokulandelana zazo zombili izinhlangothi
Zombili izinhlangothi zephrothokholi ye-TCP kufanele zigcine inombolo yokulandelana, okuyisici esibalulekile sokuqinisekisa ukudluliswa okuthembekile. Izinombolo zokulandelana zidlala indima ebalulekile ekuxhumekeni kwe-TCP.Zenza lokhu okulandelayo:
Umamukeli angasusa idatha eyimpinda futhi aqinisekise ukunemba kwedatha.
Umamukeli angathola amaphakethe ngokulandelana kwenombolo yokulandelana ukuze kuqinisekiswe ubuqotho bedatha.
● Inombolo yokulandelana ingakwazi ukuhlonza iphakethe ledatha elitholwe elinye iqembu, livumele ukudluliswa kwedatha okuthembekile.
Ngakho-ke, lapho lisungula uxhumano lwe-TCP, iklayenti lithumela amaphakethe e-SYN nenombolo yokuqala yokulandelana futhi lidinga iseva ukuthi iphendule ngephakethe le-ACK elibonisa ukwamukela ngempumelelo iphakethe le-SYN leklayenti. Bese, iseva ithumela iphakethe le-SYN elinenombolo yokuqala yokulandelana kuklayenti bese ilinda iklayenti ukuthi liphendule, unomphela, ukuze kuqinisekiswe ukuthi izinombolo zokuqala zokulandelana zivunyelaniswa ngokuthembekile.
Nakuba ukuxhawula okunezinhlangothi ezine nakho kungenzeka ukuvumelanisa ngokuthembekile izinombolo zokulandelana kwasekuqaleni kwazo zombili izinhlangothi, isinyathelo sesibili nesesithathu singahlanganiswa sibe isinyathelo esisodwa, okuholela ekuxhawulaneni kwezindlela ezintathu. Kodwa-ke, ukuxhawula okubili kungaqinisekisa kuphela ukuthi inombolo yokuqala yokulandelana yeqembu elilodwa yamukelwe ngempumelelo elinye iqembu, kodwa asikho isiqinisekiso sokuthi inombolo yokuqala yokulandelana yazo zombili izinhlangothi ingaqinisekiswa. Ngakho-ke, ukuxhawula izindlela ezintathu kuyisinqumo esingcono kakhulu ongasithatha ukuze uqinisekise ukuzinza nokuthembeka kokuxhumana kwe-TCP.
Isizathu 3: Gwema Ukumosha Izinsiza
Uma kukhona "ukuxhawula okubili", lapho isicelo se-SYN seklayenti sivinjiwe kunethiwekhi, iklayenti alikwazi ukuthola iphakethe le-ACK elithunyelwe iseva, ngakho-ke i-SYN izothunjwa. Kodwa-ke, njengoba kungekho ukuxhawula kwesithathu, iseva ayikwazi ukunquma ukuthi iklayenti likutholile yini ukuvuma kwe-ACK ukuze kusungulwe uxhumano. Ngakho-ke, iseva ingakwazi ukusungula uxhumano ngokuqhubekayo ngemva kokuthola isicelo ngasinye se-SYN. Lokhu kuholela kokulandelayo:
Ukumosha izisetshenziswa: Uma isicelo se-SYN seklayenti sivinjiwe, okuholela ekudluliselweni okuphindaphindiwe kwamaphakethe e-SYN amaningi, iseva izosungula ukuxhumana okuningi okungasasebenzi okungafuneki ngemva kokuthola isicelo. Lokhu kuholela ekumoshweni okungadingekile kwezinsiza zeseva.
Ukugcinwa komlayezo: Ngenxa yokuntuleka kokuxhawula okwesithathu, iseva ayinayo indlela yokwazi ukuthi iklayenti lithole ngokufanelekile yini ukuvuma kwe-ACK ukuze kutholwe uxhumano. Njengomphumela, uma imilayezo ibambeka kunethiwekhi, iklayenti lizoqhubeka lithumela izicelo ze-SYN ngokuphindaphindiwe, okubangela iseva ukuthi ihlale isungula ukuxhumana okusha. Lokhu kuzokhuphula ukuminyana kwenethiwekhi nokubambezeleka futhi kuthinte kabi ukusebenza kwenethiwekhi kukonke.
Ngakho-ke, ukuze kuqinisekiswe ukuzinza nokuthembeka kokuxhumeka kwenethiwekhi, i-TCP isebenzisa ukuxhawula kwezindlela ezintathu ukusungula uxhumano ukuze kugwenywe ukuvela kwalezi zinkinga.
Isifinyezo
II-Network Packet BrokerUkusungulwa koxhumano lwe-TCP kwenziwa ngokuxhawulana ngezindlela ezintathu. Ngesikhathi sokuxhawula izindlela ezintathu, iklayenti liqale lithumele iphakethe elinefulegi le-SYN kuseva, elibonisa ukuthi lifuna ukusungula uxhumano. Ngemva kokuthola isicelo esivela kuklayenti, iseva iphendula iphakethe elinamafulegi e-SYN kanye ne-ACK kuklayenti, okubonisa ukuthi isicelo sokuxhuma samukelwe, futhi ithumela inombolo yayo yokuqala yokulandelana. Ekugcineni, iklayenti liphendula ngefulegi le-ACK kuseva ukuze libonise ukuthi uxhumano lusungulwe ngempumelelo. Ngakho-ke, amaqembu amabili asesimweni ESIMISWA futhi angaqala ukuthumelana idatha.
Ngokuvamile, inqubo yezindlela ezintathu zokuxhawula ukusungulwa koxhumano lwe-TCP iklanyelwe ukuqinisekisa ukuzinza nokuthembeka kokuxhumana, ukugwema ukudideka nokumosha izinsiza ngokuxhunywa komlando, nokuqinisekisa ukuthi zombili izinhlangothi ziyakwazi ukuthola nokuthumela idatha.
Isikhathi sokuthumela: Jan-08-2025
