Sanibonani nonke, igama lami ngingu-Sasha, ngihola ukuhlolwa kwe-backend e-FunCorp. Thina, njengabanye abaningi, sisebenzise i-architecture egxile kusevisi. Ngakolunye uhlangothi, lokhu kwenza umsebenzi ube lula, ngoba... Kulula ukuhlola isevisi ngayinye ngokwehlukana, kodwa ngakolunye uhlangothi, kunesidingo sokuhlola ukusebenzisana kwezinsizakalo komunye nomunye, okuvame ukwenzeka phezu kwenethiwekhi.
Kulesi sihloko, ngizokhuluma ngezinsiza ezimbili ezingasetshenziswa ukuhlola izimo eziyisisekelo ezichaza ukusebenza kohlelo lokusebenza lapho kukhona izinkinga zenethiwekhi.
Ukulingisa izinkinga zenethiwekhi
Ngokuvamile, isofthiwe ihlolwa eziphakelini zokuhlola ezinoxhumo oluhle lwe-inthanethi. Ezimweni zokukhiqiza ezinokhahlo, izinto zingase zingabi bushelelezi kangako, ngakho-ke kwesinye isikhathi udinga ukuhlola izinhlelo ezimeni ezingezinhle zokuxhuma. Ku-Linux, insiza izosiza ngomsebenzi wokulingisa izimo ezinjalo tc.
tc(abbr. kusuka ku-Traffic Control) ikuvumela ukuthi ulungiselele ukudluliswa kwamaphakethe enethiwekhi ohlelweni. Lolu hlelo lokusebenza lunamandla amakhulu, ungafunda kabanzi ngawo . Lapha ngizocubungula ezimbalwa zazo: sinentshisekelo ekuhlelweni kwethrafikhi, esiyisebenzisayo qdisc, futhi njengoba sidinga ukulingisa inethiwekhi engazinzile, sizosebenzisa i-qdisc engenaklasi .
Ake sethule iseva ye-echo kuseva (ngisebenzise ):
ncat -l 127.0.0.1 12345 -k -c 'xargs -n1 -i echo "Response: {}"'
Ukuze ubonise ngokuningiliziwe zonke izitembu zesikhathi esinyathelweni ngasinye sokusebenzisana phakathi kweklayenti neseva, ngibhale umbhalo olula wePython othumela isicelo. test kuseva yethu ye-echo.
Ikhodi yomthombo weklayenti
#!/bin/python
import socket
import time
HOST = '127.0.0.1'
PORT = 12345
BUFFER_SIZE = 1024
MESSAGE = "Testn"
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
t1 = time.time()
print "[time before connection: %.5f]" % t1
s.connect((HOST, PORT))
print "[time after connection, before sending: %.5f]" % time.time()
s.send(MESSAGE)
print "[time after sending, before receiving: %.5f]" % time.time()
data = s.recv(BUFFER_SIZE)
print "[time after receiving, before closing: %.5f]" % time.time()
s.close()
t2 = time.time()
print "[time after closing: %.5f]" % t2
print "[total duration: %.5f]" % (t2 - t1)
print data
Ake siyiqalise futhi sibheke ithrafikhi esibonakalayo lo kanye nembobo 12345:
[user@host ~]# python client.py
[time before connection: 1578652979.44837]
[time after connection, before sending: 1578652979.44889]
[time after sending, before receiving: 1578652979.44894]
[time after receiving, before closing: 1578652979.45922]
[time after closing: 1578652979.45928]
[total duration: 0.01091]
Response: Test
Ukulahlwa kwethrafikhi
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
10:42:59.448601 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [S], seq 3383332866, win 43690, options [mss 65495,sackOK,TS val 606325685 ecr 0,nop,wscale 7], length 0
10:42:59.448612 IP 127.0.0.1.12345 > 127.0.0.1.54054: Flags [S.], seq 2584700178, ack 3383332867, win 43690, options [mss 65495,sackOK,TS val 606325685 ecr 606325685,nop,wscale 7], length 0
10:42:59.448622 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 606325685 ecr 606325685], length 0
10:42:59.448923 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 606325685 ecr 606325685], length 5
10:42:59.448930 IP 127.0.0.1.12345 > 127.0.0.1.54054: Flags [.], ack 6, win 342, options [nop,nop,TS val 606325685 ecr 606325685], length 0
10:42:59.459118 IP 127.0.0.1.12345 > 127.0.0.1.54054: Flags [P.], seq 1:15, ack 6, win 342, options [nop,nop,TS val 606325696 ecr 606325685], length 14
10:42:59.459213 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [.], ack 15, win 342, options [nop,nop,TS val 606325696 ecr 606325696], length 0
10:42:59.459268 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [F.], seq 6, ack 15, win 342, options [nop,nop,TS val 606325696 ecr 606325696], length 0
10:42:59.460184 IP 127.0.0.1.12345 > 127.0.0.1.54054: Flags [F.], seq 15, ack 7, win 342, options [nop,nop,TS val 606325697 ecr 606325696], length 0
10:42:59.460196 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [.], ack 16, win 342, options [nop,nop,TS val 606325697 ecr 606325697], length 0
Konke kusezingeni: ukuxhawula izindlela ezintathu, i-PSH/ACK kanye ne-ACK ekuphenduleni kabili - lokhu ukushintshana kwesicelo nempendulo phakathi kweklayenti neseva, kanye ne-FIN/ACK kanye ne-ACK kabili - ukuqedela uxhumano.
Ukubambezeleka kwephakethe
Manje ake sisethe ukubambezeleka kube ama-millisecond angu-500:
tc qdisc add dev lo root netem delay 500ms
Sethula iklayenti futhi sibona ukuthi umbhalo manje usebenza imizuzwana emi-2:
[user@host ~]# ./client.py
[time before connection: 1578662612.71044]
[time after connection, before sending: 1578662613.71059]
[time after sending, before receiving: 1578662613.71065]
[time after receiving, before closing: 1578662614.72011]
[time after closing: 1578662614.72019]
[total duration: 2.00974]
Response: Test
Yini esemgwaqweni? Ake sibheke:
Ukulahlwa kwethrafikhi
13:23:33.210520 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [S], seq 1720950927, win 43690, options [mss 65495,sackOK,TS val 615958947 ecr 0,nop,wscale 7], length 0
13:23:33.710554 IP 127.0.0.1.12345 > 127.0.0.1.58694: Flags [S.], seq 1801168125, ack 1720950928, win 43690, options [mss 65495,sackOK,TS val 615959447 ecr 615958947,nop,wscale 7], length 0
13:23:34.210590 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 615959947 ecr 615959447], length 0
13:23:34.210657 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 615959947 ecr 615959447], length 5
13:23:34.710680 IP 127.0.0.1.12345 > 127.0.0.1.58694: Flags [.], ack 6, win 342, options [nop,nop,TS val 615960447 ecr 615959947], length 0
13:23:34.719371 IP 127.0.0.1.12345 > 127.0.0.1.58694: Flags [P.], seq 1:15, ack 6, win 342, options [nop,nop,TS val 615960456 ecr 615959947], length 14
13:23:35.220106 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [.], ack 15, win 342, options [nop,nop,TS val 615960957 ecr 615960456], length 0
13:23:35.220188 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [F.], seq 6, ack 15, win 342, options [nop,nop,TS val 615960957 ecr 615960456], length 0
13:23:35.720994 IP 127.0.0.1.12345 > 127.0.0.1.58694: Flags [F.], seq 15, ack 7, win 342, options [nop,nop,TS val 615961457 ecr 615960957], length 0
13:23:36.221025 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [.], ack 16, win 342, options [nop,nop,TS val 615961957 ecr 615961457], length 0
Ungabona ukuthi i-lag elindelekile yesigamu sesekhondi ivele ekusebenzisaneni phakathi kweklayenti neseva. Uhlelo luziphatha ngokuthakazelisa kakhulu uma i-lag inkulu: i-kernel iqala ukuthumela amanye amaphakethe e-TCP. Masiguqule ukubambezeleka kube isekhondi elingu-1 futhi sibheke ithrafikhi (ngeke ngibonise okukhiphayo kweklayenti, kukhona amasekhondi angu-4 alindelekile ubude besikhathi esiphelele):
tc qdisc change dev lo root netem delay 1s
Ukulahlwa kwethrafikhi
13:29:07.709981 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [S], seq 283338334, win 43690, options [mss 65495,sackOK,TS val 616292946 ecr 0,nop,wscale 7], length 0
13:29:08.710018 IP 127.0.0.1.12345 > 127.0.0.1.39306: Flags [S.], seq 3514208179, ack 283338335, win 43690, options [mss 65495,sackOK,TS val 616293946 ecr 616292946,nop,wscale 7], length 0
13:29:08.711094 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [S], seq 283338334, win 43690, options [mss 65495,sackOK,TS val 616293948 ecr 0,nop,wscale 7], length 0
13:29:09.710048 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 616294946 ecr 616293946], length 0
13:29:09.710152 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 616294947 ecr 616293946], length 5
13:29:09.711120 IP 127.0.0.1.12345 > 127.0.0.1.39306: Flags [S.], seq 3514208179, ack 283338335, win 43690, options [mss 65495,sackOK,TS val 616294948 ecr 616292946,nop,wscale 7], length 0
13:29:10.710173 IP 127.0.0.1.12345 > 127.0.0.1.39306: Flags [.], ack 6, win 342, options [nop,nop,TS val 616295947 ecr 616294947], length 0
13:29:10.711140 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 616295948 ecr 616293946], length 0
13:29:10.714782 IP 127.0.0.1.12345 > 127.0.0.1.39306: Flags [P.], seq 1:15, ack 6, win 342, options [nop,nop,TS val 616295951 ecr 616294947], length 14
13:29:11.714819 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [.], ack 15, win 342, options [nop,nop,TS val 616296951 ecr 616295951], length 0
13:29:11.714893 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [F.], seq 6, ack 15, win 342, options [nop,nop,TS val 616296951 ecr 616295951], length 0
13:29:12.715562 IP 127.0.0.1.12345 > 127.0.0.1.39306: Flags [F.], seq 15, ack 7, win 342, options [nop,nop,TS val 616297952 ecr 616296951], length 0
13:29:13.715596 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [.], ack 16, win 342, options [nop,nop,TS val 616298952 ecr 616297952], length 0
Kuyabonakala ukuthi iklayenti lithumele iphakethe le-SYN kabili, futhi iseva ithumele i-SYN/ACK kabili.
Ngokungeziwe enanini elingaguquki, ukubambezeleka kungase kusethelwe ekuchezukeni, umsebenzi wokusabalalisa, kanye nokuhlobana (ngenani lephakethe langaphambilini). Lokhu kwenziwa kanje:
tc qdisc change dev lo root netem delay 500ms 400ms 50 distribution normal
Lapha sibeke ukubambezeleka phakathi kwama-millisecond ayi-100 nangama-900, amanani azokhethwa ngokuya ngokusatshalaliswa okuvamile futhi kuzoba nokuhlobana okungu-50% nenani lokulibaziseka lephakethe langaphambilini.
Kungenzeka ukuthi uqaphele ukuthi umyalo wokuqala engiwusebenzisile engeza, bese ushintsho. Incazelo yale miyalo isobala, ngakho-ke ngizonezela nje ukuthi kukhona okwengeziwe i-del, engasetshenziswa ukususa ukumisa.
Ukulahlekelwa Kwephakethe
Manje ake sizame ukwenza ukulahleka kwephakethe. Njengoba kubonakala kumadokhumenti, lokhu kungenziwa ngezindlela ezintathu: ukulahlekelwa amaphakethe ngokungahleliwe ngokungenzeka okuthile, kusetshenziswa uchungechunge lwe-Markov lwezifunda ezingu-2, 3 noma ezi-4 ukubala ukulahlekelwa kwephakethe, noma ukusebenzisa imodeli ye-Elliott-Gilbert. Esihlokweni ngizocabangela indlela yokuqala (elula futhi esobala kakhulu), futhi ungafunda ngabanye .
Masenze ukulahleka kwamaphakethe angama-50% ngokuhlangana kwe-25%:
tc qdisc add dev lo root netem loss 50% 25%
Ngeshwa tcpdump ngeke ukwazi ukusikhombisa ngokucacile ukulahleka kwamaphakethe, sizocabanga kuphela ukuthi kusebenza ngempela. Futhi isikhathi esikhulisiwe nesingazinzile sombhalo sizosisiza siqinisekise lokhu. client.py (ingaqedelwa khona manjalo, noma mhlawumbe kumasekhondi angama-20), kanye nenani elikhulayo lamaphakethe adluliselwe kabusha:
[user@host ~]# netstat -s | grep retransmited; sleep 10; netstat -s | grep retransmited
17147 segments retransmited
17185 segments retransmited
Ukwengeza umsindo emaphaketheni
Ngokungeziwe ekulahlekeni kwephakethe, ungalingisa ukulimala kwephakethe: umsindo uzovela endaweni yephakethe engahleliwe. Masenze umonakalo wephakethe ngamathuba angama-50% futhi ngaphandle kokuxhumana:
tc qdisc change dev lo root netem corrupt 50%
Sisebenzisa umbhalo weklayenti (akukho okuthakazelisayo lapho, kodwa kuthathe imizuzwana emi-2 ukuqeda), bheka ithrafikhi:
Ukulahlwa kwethrafikhi
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
10:20:54.812434 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [S], seq 2023663770, win 43690, options [mss 65495,sackOK,TS val 1037001049 ecr 0,nop,wscale 7], length 0
10:20:54.812449 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [S.], seq 2104268044, ack 2023663771, win 43690, options [mss 65495,sackOK,TS val 1037001049 ecr 1037001049,nop,wscale 7], length 0
10:20:54.812458 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 1037001049 ecr 1037001049], length 0
10:20:54.812509 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1037001049 ecr 1037001049], length 5
10:20:55.013093 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1037001250 ecr 1037001049], length 5
10:20:55.013122 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [.], ack 6, win 342, options [nop,nop,TS val 1037001250 ecr 1037001250], length 0
10:20:55.014681 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [P.], seq 1:15, ack 6, win 342, options [nop,nop,TS val 1037001251 ecr 1037001250], length 14
10:20:55.014745 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [.], ack 15, win 340, options [nop,nop,TS val 1037001251 ecr 1037001251], length 0
10:20:55.014823 IP 127.0.0.1.43666 > 127.0.0.5.12345: Flags [F.], seq 2023663776, ack 2104268059, win 342, options [nop,nop,TS val 1037001251 ecr 1037001251], length 0
10:20:55.214088 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [P.], seq 1:15, ack 6, win 342, options [nop,unknown-65 0x0a3dcf62eb3d,[bad opt]>
10:20:55.416087 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [F.], seq 6, ack 15, win 342, options [nop,nop,TS val 1037001653 ecr 1037001251], length 0
10:20:55.416804 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [F.], seq 15, ack 7, win 342, options [nop,nop,TS val 1037001653 ecr 1037001653], length 0
10:20:55.416818 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [.], ack 16, win 343, options [nop,nop,TS val 1037001653 ecr 1037001653], length 0
10:20:56.147086 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [F.], seq 15, ack 7, win 342, options [nop,nop,TS val 1037002384 ecr 1037001653], length 0
10:20:56.147101 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [.], ack 16, win 342, options [nop,nop,TS val 1037002384 ecr 1037001653], length 0
Kuyabonakala ukuthi amanye amaphakethe athunyelwe ngokuphindaphindiwe futhi kunephakethe elilodwa elinemethadatha ephukile: izinketho [nop,unknown-65 0x0a3dcf62eb3d,[bad opt]>. Kodwa into eyinhloko ukuthi ekugcineni konke kwasebenza kahle - i-TCP ibhekane nomsebenzi wayo.
Ukuphindaphinda kwephakethe
Yini enye ongayenza ngayo netem? Isibonelo, lingisa isimo esiphambene sokulahleka kwephakethe—ukuphindaphinda kwephakethe. Lo myalo futhi uthatha izimpikiswano ezi-2: amathuba nokuhlobana.
tc qdisc change dev lo root netem duplicate 50% 25%
Ukushintsha ukuhleleka kwamaphakheji
Ungaxuba izikhwama ngezindlela ezimbili.
Kowokuqala, amanye amaphakethe athunyelwa ngokushesha, amanye anokubambezeleka okucacisiwe. Isibonelo esivela kumadokhumenti:
tc qdisc change dev lo root netem delay 10ms reorder 25% 50%
Ngamathuba angu-25% (kanye nokuhlanganiswa kwe-50%) iphakethe lizothunyelwa ngokushesha, okusele kuzothunyelwa ngokubambezeleka kwama-millisecond angu-10.
Indlela yesibili yilapho iphakethe ngalinye le-Nth lithunyelwa khona manjalo ngamathuba anikeziwe (kanye nokuhlobana), bese elinye libe nokubambezeleka okunikeziwe. Isibonelo esivela kumadokhumenti:
tc qdisc change dev lo root netem delay 10ms reorder 25% 50% gap 5
Iphakheji ngayinye yesihlanu inamathuba angu-25% okuthunyelwa ngaphandle kokulibala.
Ukushintsha Umkhawulokudonsa
Ngokuvamile yonke indawo ababhekisela kuyo , kodwa ngosizo netem Ungashintsha futhi umkhawulokudonsa wesixhumi esibonakalayo:
tc qdisc change dev lo root netem rate 56kbit
Leli qembu lizokwenza uhambo lokuzungeza localhost kubuhlungu njengokusefa i-inthanethi ngemodemu yokudayela. Ngokungeziwe ekusetheni i-bitrate, ungaphinda ulingise imodeli yephrothokholi yesendlalelo sesixhumanisi: setha isihloko esiphezulu sephakethe, usayizi weseli, kanye nangaphezulu kweseli. Ngokwesibonelo, lokhu kungalingiswa kanye ne-bitrate 56 kbit/sec:
tc qdisc change dev lo root netem rate 56kbit 0 48 5
Ilingisa ukuphela kwesikhathi sokuxhuma
Elinye iphuzu elibalulekile ohlelweni lokuhlola lapho wamukela isofthiwe ukuphela kwesikhathi. Lokhu kubalulekile ngoba ezinhlelweni ezisabalalisiwe, lapho enye yezinsizakalo ikhubazekile, ezinye kufanele zibuyele kwabanye ngesikhathi noma zibuyisele iphutha kuklayenti, futhi akufanele zivele zilenga, zilinde impendulo noma ukuxhumana. azosungulwa.
Kunezindlela ezimbalwa zokwenza lokhu: isibonelo, sebenzisa imbumbulu engaphenduli, noma xhuma enqubweni usebenzisa isilungisi sephutha, ubeke indawo yokuphumula endaweni efanele futhi umise inqubo (lena cishe indlela ehlanekezelwe kakhulu). Kodwa okunye okusobala kakhulu i-firewall port noma i-host. Kuzosisiza kulokhu .
Ukuze sibonise, sizofaka i-firewall port 12345 futhi sisebenzise umbhalo weklayenti lethu. Ungakwazi ukufaka i-firewall amaphakethe aphumayo kulesi sikhungo kumthumeli noma kumaphakethe angenayo kumamukeli. Ezibonelweni zami, amaphakethe angenayo azofakwa ngomlilo (sisebenzisa i-chain INPUT kanye nenketho --Dport). Amaphakethe anjalo angaba DROP, REJECT noma REJECT ngefulegi le-TCP RST, noma nomsingathi we-ICMP ongafinyeleleki (eqinisweni, ukuziphatha okuzenzakalelayo icmp-port-ayifinyeleleki, futhi kukhona nethuba lokuthumela impendulo icmp-net-ayifinyeleleki, icmp-proto-engafinyeleleki, i-icmp-net-enqatshelwe и i-icmp-host-enqatshelwe).
DLULA
Uma kunomthetho othi DROP, amaphakethe azomane “anyamalale”.
iptables -A INPUT -p tcp --dport 12345 -j DROP
Sethula iklayenti bese sibona ukuthi liyaba yiqhwa esigabeni sokuxhuma kuseva. Ake sibheke ithrafikhi:
Ukulahlwa kwethrafikhi
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
08:28:20.213506 IP 127.0.0.1.32856 > 127.0.0.1.12345: Flags [S], seq 3019694933, win 43690, options [mss 65495,sackOK,TS val 1203046450 ecr 0,nop,wscale 7], length 0
08:28:21.215086 IP 127.0.0.1.32856 > 127.0.0.1.12345: Flags [S], seq 3019694933, win 43690, options [mss 65495,sackOK,TS val 1203047452 ecr 0,nop,wscale 7], length 0
08:28:23.219092 IP 127.0.0.1.32856 > 127.0.0.1.12345: Flags [S], seq 3019694933, win 43690, options [mss 65495,sackOK,TS val 1203049456 ecr 0,nop,wscale 7], length 0
08:28:27.227087 IP 127.0.0.1.32856 > 127.0.0.1.12345: Flags [S], seq 3019694933, win 43690, options [mss 65495,sackOK,TS val 1203053464 ecr 0,nop,wscale 7], length 0
08:28:35.235102 IP 127.0.0.1.32856 > 127.0.0.1.12345: Flags [S], seq 3019694933, win 43690, options [mss 65495,sackOK,TS val 1203061472 ecr 0,nop,wscale 7], length 0
Kungabonakala ukuthi iklayenti lithumela amaphakethe e-SYN anesikhathi sokuvala esikhula ngokuphawulekayo. Ngakho sithole iphutha elincane kuklayenti: udinga ukusebenzisa indlela isikhathi sokuvala()ukukhawulela isikhathi lapho iklayenti lizozama ukuxhuma kuseva.
Sisusa ngokushesha umthetho:
iptables -D INPUT -p tcp --dport 12345 -j DROPUngasusa yonke imithetho ngesikhathi esisodwa:
iptables -F
Uma usebenzisa i-Docker futhi udinga ukufaka i-firewall yonke ithrafikhi eya esitsheni, ungakwenza ngale ndlela elandelayo:
iptables -I DOCKER-USER -p tcp -d CONTAINER_IP -j DROP
Yenqaba
Manje ake sengeze umthetho ofanayo, kodwa nge-REJECT:
iptables -A INPUT -p tcp --dport 12345 -j REJECT
Iklayenti liphuma ngemva kwesekhondi ngephutha [Errno 111] Ukuxhumeka kunqatshiwe. Ake sibheke ithrafikhi ye-ICMP:
[user@host ~]# tcpdump -i lo -nn icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
08:45:32.871414 IP 127.0.0.1 > 127.0.0.1: ICMP 127.0.0.1 tcp port 12345 unreachable, length 68
08:45:33.873097 IP 127.0.0.1 > 127.0.0.1: ICMP 127.0.0.1 tcp port 12345 unreachable, length 68
Kuyabonakala ukuthi iklayenti lithole kabili imbobo ayifinyeleleki bese iphetha ngephutha.
NQABA nge-tcp-reset
Ake sizame ukwengeza inketho --nqaba-ngokusetha kabusha kwe-tcp:
iptables -A INPUT -p tcp --dport 12345 -j REJECT --reject-with tcp-reset
Kulokhu, iklayenti liphuma ngokushesha ngephutha, ngoba isicelo sokuqala sithole iphakethe le-RST:
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
09:02:52.766175 IP 127.0.0.1.60658 > 127.0.0.1.12345: Flags [S], seq 1889460883, win 43690, options [mss 65495,sackOK,TS val 1205119003 ecr 0,nop,wscale 7], length 0
09:02:52.766184 IP 127.0.0.1.12345 > 127.0.0.1.60658: Flags [R.], seq 0, ack 1889460884, win 0, length 0
NQABA nge-icmp-host-engafinyeleleki
Ake sizame enye inketho yokusebenzisa REJECT:
iptables -A INPUT -p tcp --dport 12345 -j REJECT --reject-with icmp-host-unreachable
Iklayenti liphuma ngemva kwesekhondi ngephutha [Errno 113] Awukho umzila wokuba usokhaya, sibona kuthrafikhi ye-ICMP I-ICMP host 127.0.0.1 ayifinyeleleki.
Ungazama futhi amanye amapharamitha we-REJECT, futhi ngizogxila kulokhu :)
Ukulingisa isikhathi sokuvala isicelo
Esinye isimo yilapho iklayenti likwazi ukuxhuma kuseva, kodwa alikwazi ukuthumela isicelo kuyo. Indlela yokuhlunga amaphakethe ukuze ukuhlunga kungaqali ngokushesha? Uma ubheka ithrafikhi yanoma yikuphi ukuxhumana phakathi kweklayenti kanye neseva, uzobona ukuthi lapho usungula uxhumano, kuphela amafulege we-SYN ne-ACK asetshenziswa, kodwa lapho kuhwetshwa idatha, iphakethe lokugcina lesicelo lizoqukatha ifulegi le-PSH. Ifaka ngokuzenzakalela ukuze igweme ukugcina kumthamo. Ungasebenzisa lolu lwazi ukuze udale isihlungi: sizovumela wonke amaphakethe ngaphandle kwalawo aqukethe ifulegi le-PSH. Ngakho, uxhumano luzosungulwa, kodwa iklayenti ngeke likwazi ukuthumela idatha kuseva.
DLULA
Ku-DROP umyalo ungabukeka kanje:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j DROP
Yethula iklayenti futhi ubuke ithrafikhi:
Ukulahlwa kwethrafikhi
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
10:02:47.549498 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [S], seq 2166014137, win 43690, options [mss 65495,sackOK,TS val 1208713786 ecr 0,nop,wscale 7], length 0
10:02:47.549510 IP 127.0.0.1.12345 > 127.0.0.1.49594: Flags [S.], seq 2341799088, ack 2166014138, win 43690, options [mss 65495,sackOK,TS val 1208713786 ecr 1208713786,nop,wscale 7], length 0
10:02:47.549520 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 1208713786 ecr 1208713786], length 0
10:02:47.549568 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1208713786 ecr 1208713786], length 5
10:02:47.750084 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1208713987 ecr 1208713786], length 5
10:02:47.951088 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1208714188 ecr 1208713786], length 5
10:02:48.354089 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1208714591 ecr 1208713786], length 5
Siyabona ukuthi ukuxhumeka kumisiwe futhi iklayenti alikwazi ukuthumela idatha kuseva.
Yenqaba
Kulesi simo ukuziphatha kuzoba okufanayo: iklayenti ngeke likwazi ukuthumela isicelo, kodwa lizothola I-ICMP 127.0.0.1 tcp port 12345 ayifinyeleleki futhi andise isikhathi phakathi kokuthunyelwa kabusha kwesicelo ngokwandayo. Umyalo ubukeka kanje:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j REJECT
NQABA nge-tcp-reset
Umyalo ubukeka kanje:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j REJECT --reject-with tcp-reset
Sesivele sikwazi lokho uma usebenzisa --nqaba-ngokusetha kabusha kwe-tcp iklayenti lizothola iphakethe le-RST ekuphenduleni, ngakho ukuziphatha kungabikezelwa: ukuthola iphakethe le-RST ngenkathi uxhumano lusungulwa kusho ukuthi isokhethi ivalwe ngokungalindelekile ngakolunye uhlangothi, okusho ukuthi iklayenti kufanele lithole. Uxhumano lusethwe kabusha ngontanga. Masiqhube iskripthi sethu futhi siqiniseke ngalokhu. Futhi nansi indlela ithrafikhi ezobukeka ngayo:
Ukulahlwa kwethrafikhi
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
10:22:14.186269 IP 127.0.0.1.52536 > 127.0.0.1.12345: Flags [S], seq 2615137531, win 43690, options [mss 65495,sackOK,TS val 1209880423 ecr 0,nop,wscale 7], length 0
10:22:14.186284 IP 127.0.0.1.12345 > 127.0.0.1.52536: Flags [S.], seq 3999904809, ack 2615137532, win 43690, options [mss 65495,sackOK,TS val 1209880423 ecr 1209880423,nop,wscale 7], length 0
10:22:14.186293 IP 127.0.0.1.52536 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 1209880423 ecr 1209880423], length 0
10:22:14.186338 IP 127.0.0.1.52536 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1209880423 ecr 1209880423], length 5
10:22:14.186344 IP 127.0.0.1.12345 > 127.0.0.1.52536: Flags [R], seq 3999904810, win 0, length 0
NQABA nge-icmp-host-engafinyeleleki
Ngicabanga ukuthi sekuvele kusobala kuwo wonke umuntu ukuthi umyalo uzobukeka kanjani :) Ukuziphatha kweklayenti kuleli cala kuzohluka kancane kulokho nge-REJECT elula: iklayenti ngeke ikhulise isikhathi sokuvala phakathi kwemizamo yokuthumela kabusha iphakethe.
[user@host ~]# tcpdump -i lo -nn icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
10:29:56.149202 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:56.349107 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:56.549117 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:56.750125 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:56.951130 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:57.152107 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:57.353115 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
isiphetho
Akudingekile ukubhala inhlekisa ukuze uhlole ukusebenzisana kwesevisi neklayenti elilengayo noma iseva; ngesinye isikhathi kwanele ukusebenzisa izinsiza ezijwayelekile ezitholakala ku-Linux.
Izinsiza okuxoxwe ngazo esihlokweni zinamakhono angaphezu kwalawo achaziwe, ngakho-ke ungathola ezinye zezinketho zakho zokuzisebenzisa. Ngokwami, ngihlale nginenele ngalokho engibhale ngakho (empeleni, ngisho nangaphansi). Uma usebenzisa lezi noma izinsiza ezifanayo ekuhloleni enkampanini yakho, sicela ubhale ukuthi kanjani kahle. Uma kungenjalo, ngithemba ukuthi isoftware yakho izoba ngcono uma unquma ukuyihlola ezimeni zezinkinga zenethiwekhi usebenzisa izindlela eziphakanyisiwe.
Source: www.habr.com