MTU noma MSS? Ushintsho lwe-VPN lulungisa ini ngempela
I-MTU ikhawulela okuthwalwa yisixhumanisi; i-MSS ikhawulela umthwalo we-TCP ongaphakathi. Khawulela okulungile futhi wazi ukuthi yiziphi izinqubo ezingamboziwe yikho kokubili.
Ama-ping ayaphumelela, ukudluliswa okukhulu kuyakhungatheka, futhi ithulametha izibika ukuthi inempilo. Othile wehlisa i-MTU yesixhumanisi, omunye ukhawulela i-MSS, futhi ngezinye izikhathi inkinga iyanyamalala ngenxa yezizathu okungekho muntu ozibhalayo. Lezi zinombolo ezimbili zichaza izinto ezihlukene, ngakho ukushintsha okungalungile kuveza ukulungiswa okubonakala njengenhlanhla. Nansi inqubo: khomba isigaba, sebenzisa ukulungiswa okuhambisanayo, bese uhlola kuxhumano olusha.
Izinombolo ezimbili, izinto ezimbili
I-MTU ingeyesixhumanisi noma ingeyesixhumanisi sokuxhumana: iyiphakethe elikhulu kakhulu elingadluliswa ngaphandle kokuhlukaniswa. I-MSS ingeye-TCP: inani elikhulu kakhulu lomthwalo we-TCP iphakethe eliwukulinganisa lingawuthwala, futhi ayifaki isihloko se-TCP kanye nese-IP. Kusixhumanisi esijwayelekile se-Ethernet esine-IPv4, i-MTU engama-1500 byte inika i-MSS eyaziwayo engama-1460 byte. Lezi zinombolo zichaza izigaba ezihlukene futhi zishintshwa ngezindlela ezihlukene. Kulula ukuzidida ngoba zombili zikalwa ngama-byte futhi zombili ziseduze no-1500.
Enye ifika njengesilungiselelo sesixhumanisi. Enye ifika njengokukhetha ngaphakathi kwengxenye ye-SYN, okuxoxwa ngayo phakathi kweziphetho ezingakaze zibone isixhumanisi sakho.
Umthwalo owengeziwe wangaphandle uhlala kuphi
I-VPN ifaka iphakethe langaphakathi kwelinye, futhi iphakethe langaphandle kufanele lingene endleleni yomzimba. Izihloko zokuhlanganisa, isihloko se-IP sangaphandle, isihloko sokuthutha kanye nanoma iyiphi ithegi yokuqinisekisa zonke zisebenzisa ama-byte iphakethe langaphakathi elingakwazi ukuwasebenzisa. Shiya isixhumanisi sethulametha ku-1500 futhi iphakethe langaphandle lizodlula njalo lokho umzila ongakuthwala. Uma ibhithi ethi 'ungahlukanisi' isethiwe, umzila uyilahla futhi kufanele ibuyisele iphutha le-ICMP; uma lelo phutha lihlungiwe, umthumeli akazi neze.
Yingakho ukwehluleka kubonakala kukhethile. Izicelo ezincane ziyaphela futhi noma yini egcwalisa ingxenye iyakhungatheka, ngoba kuphela amaphakethe amakhulu alahliwe. Ithulametha elivumela i-ping ukuba lidlule akuwona ithulametha elithwala idatha.
Ukukhawulela kwe-MSS, nokuthi kusebenza kuphi
Ukukhawulela kwe-MSS kubhala kabusha inani kungxenye ye-SYN njengoba idlula iphuzu elikhethiwe, okwenza iziphetho zombili zikhethe umthwalo omncane ngaphandle kokwazi ukuthi kungani. Ku-Linux lokhu kuyimpokophelo yethebula le-mangle elisetshenziswa umthetho ocacile, futhi kufanele shaye amaphakethe e-SYN endleleni oyifunayo. Kukhawulele kusixhumanisi sethulametha kanye nobubanzi bamakheli, ngoba umthetho obanzi ushintsha ukuziphatha kwethrafikhi engalokothi ingene ethulametha.
Umthelela uku-TCP kuphela. Uhlelo lwe-UDP, iseshini ye-QUIC kanye nanoma iyiphi inqubo ezakhela eyayo idatha ayithinteki.
Hlola ngomzila oqinile
Gcina okuguqukayo okukodwa ngesikhathi. Hlola ngephakethe ozikhethela lona usayizi, futhi setha ifulegi elithi 'ungahlukanisi' ukuze i-kernel ibike umphumela esikhundleni sokuwufihla.
Bhala ukuthi ukwehluleka kuqala kuphi: ngaphakathi ethulametha, kusixhumanisi sethulametha, noma endleleni yomzimba ngemva kokuhlanganisa. Bese ushintsha inombolo eyodwa hhayi enye, phinda lokho kuhlola. Izixhumano ezikhona zigcina i-MSS ekuxoxwe ngayo, ngakho ukushintsha kwenqubomgomo kubonakala kuphela kuxhumano olusha, yingakho ikhasi eligciniwe lingafakazi lutho kunoma iyiphi indlela. Uma ukulayisha okukhulu okukodwa kuqala ukusebenza, ufunde ngalowo mzila hhayi ngayo yonke inqubo kuwo.
Okungakulungisi ukushintsha ngakunye
Ukwehlisa i-MTU yesixhumanisi akukushintshi i-MSS yeseshini esivele isungulwe. Ukukhawulela i-MSS akusizi ukugeleza kwe-UDP, futhi akulungisi umzila lapho amaphutha e-ICMP ehlungwa ngasohlangothini olulodwa kuphela. Ukushintsha ngakunye kulungisa isigaba esisodwa sezinkinga futhi kushiya ezinye njengoba zinjalo.
Bhala ukuthi yikuphi ukulungiswa okusebenzisile, kuphi, nokuthi yikuphi ukuhlola okubonise umehluko, ngaphandle kwalokho unjiniyela olandelayo uzosebenzisa kokubili futhi alahlekelwe amandla okusho ukuthi yikuphi okwakubalulekile. Uma umkhawulo ungokoqobo futhi unomphela, khetha i-MTU yethulametha ekhombisa wona kunokukhawulela okukufihlayo. Uma kufanele ukhawulele, shiya umthetho unobubanzi futhi unombhalo, ngoba umthetho we-mangle ongachazwanga uba ngowaphakade ngokuzenzekelayo.