Umhume omnyama we-MTU: kungani izicelo ezincane zisebenza kodwa ukulayisha kuyama

Izicelo ezincane ziyaqeda kuyilapho ukulayisha okukhulu kulenga unomphela, futhi umthumeli akakwazi ukuthi indlela incane. Linganisa usayizi oqondile lapho kugqashuka khona.

Ikhasi liyafakwa, ucingo oluncane lwe-API luyabuya, bese ukulayisha ifayela kulenga kuze kube umakhasimende eyeka. Akukho lutho kungobo yomshini okuchaza lokhu, ngoba amaphakethe alahlwa phakathi nendlela ngaphandle kokuthi impendulo ewusizo ibuyiselwe. Lelo phethini iwumhume omnyama we-MTU: isixhumanisi esincane kunalokho umthumeli acabanga, kanye nokwenqaba buthule ukusho lokho. Usayizi ohlulekayo uyaphindeka, futhi yilokho okwenza kube nokwenzeka ukuxilonga.

Yini eyenza umhume ube mnyama

Sonke isixhumanisi sinendlela ephezulu yokudlulisa, futhi iphakethe elikhulu kunomkhawulo wehop elilandelayo kufanele lihlukaniswe noma lenqatshwe ngomlayezo we-ICMP osho lokho. Ukutholakala kwe-MTU yendlela kuncike ekutheni lowo mlayezo ufika futhi uhlonishwe. Ukuwuhlunga noma ukuwushaya indiva kushiya umthumeli ephinda iphakethe elingenakulingana nakancane.

Ukuhlanganisa kuyenza lokhu kube yinto evamile eduze kwama-VPN, ngoba umhubhe wengeza isihloko sangaphandle kwiphakethe ebelivele silinganiselwe isixhumanisi somzimba. Iphakethe langaphakathi livumelekile kuma-byte angu-1500 kanti elihlanganisiwe alivumelekile, ngakho liyafa emngceleni ngesikhathi amaphakethe amancane edlula. Ukuxhawula okuqediwe nekhasi lokungena elisebenzayo kufakazela kuphela ukuthi amaphakethe amancane ayasebenza. Iphakethe elikhulu kakhulu uhlelo oluzama ukulithumela yilo elibalulekile.

Thola usayizi lapho kugqashuka khona

Sesha ngezinombolo ezimbili usayizi womthwalo ngokuhlolwa kokungahlukanisi, kusuka kusibungu esingakolunye uhlangothi lomhubhe kuye kwesinye. Umthwalo omkhulu odlulayo yi-MTU yendlela esebenzisekayo kususwa izindleko zesihloko.

ping -M do -s 1400 -c 2 192.0.2.20
ping -M do -s 1200 -c 2 192.0.2.20
ping -f -l 1372 192.0.2.20

Umthwalo wama-byte angu-1472 udlula endleleni ye-Ethernet ehlanzekile yama-byte angu-1500 uma kunezelwa ama-byte angu-28 ezinhloko ze-IPv4 ne-ICMP. Lapho ukuhlolwa okufanayo kuphumelela kuphela ngomthwalo omncane ngemva kokuthi umhubhe ukhuphuke, umehluko yizindleko zokuhlanganisa, futhi umngcele womhubhe yindawo okwakufanele kukhiqizwe khona umlayezo wokwenqaba. Bhala zombili izinombolo, ngaphambi nangemva kokuxhuma, ngoba leyo mbhangqwana iwubufakazi. Phinda ukuhlolwa kwe-IPv6 lapho uhlelo luyisebenzisa, ngoba isihloko sikhulu futhi umkhawulo wokwehluleka uyashintsha.

Funda ubufakazi ngaphambi kokusola umhubhe

Amaphutha ezinhlelo ezikude, ukuminyana nokulahleka okuvamile nakho kubangela ukulayisha kume, ngakho ukudluliswa okukodwa okuhlulekile akukhombo umhume omnyama. Okuhlukanisayo ubudlelwano bosayizi: impumelelo ephindekayo kuma-byte angu-1200 nokuma okuphindekayo kuma-byte angu-1400, endleleni efanayo, endaweni yokugcina efanayo.

Ukubamba emikhawulweni yomibili kubonisa amaphakethe amakhulu ephuma futhi engafiki nakancane, ngaphandle kokwenqaba phakathi. Yileso sikhathi sokubheka idivayisi yomngcele esikhundleni somshini, oyiphendula zonke izicelo ezizitholayo ngempela. Ukuminyana nakho kuyama, kodwa kuma osayizi abehlukene ngezikhathi ezihlukene, futhi leso yisiginesha ehlukile.

Qinisekisa ukulungiswa kuzo zombili izindlela zokudlulisa

Ukulungiswa okusekelwayo ukuvumela umngcele ukuthi ubike umkhawulo wangempela, noma ukucindezela lapho usayizi ophezulu wesigaba se-TCP ukuze kungazanywa sigaba esikhulu kakhulu. Ukwehlisa i-MTU ngayinye kunethiwekhi, noma ukucisha i-firewall, kufihla uphawu futhi kushiye ukulungiselelwa okungeke kukwazi ukucabangwa ngakho kamuva.

ip link show dev tun0
sudo nft list ruleset | grep -i -E 'mtu|mss'
sysctl net.ipv4.tcp_mtu_probing
ping -M do -s 1400 -c 2 192.0.2.20

Qinisekisa ngokuhlolwa kosayizi okufanayo, bese ngohlelo olwahluleka, futhi uhlole iphrothokholi yesibili, ngoba izinhlelo ze-UDP azikaze zithole ukulungiswa kosayizi wesigaba se-TCP. Gcina amanani okuqala kuthikithi, ngoba ukulungiswa okungeke kubuyiselwe kuyinkinga yesibili elindele ukwenzeka. Uma ukuhlolwa kosayizi kudlula kodwa ukulayisha kusama, umhume omnyama wawungeyona imbangela, futhi uphenyo kufanele luqhubeke esikhundleni sokwandisa ushintsho.

Izihloko ezihlobene