Tena koutou katoa, ko Sasha toku ingoa, kei te arahi ahau i nga whakamatautau tuara i FunCorp. Ko matou, pera i etahi atu, kua whakatinanahia he hoahoanga mahi-mahi. I tetahi taha, ka ngawari te mahi, na te mea ... He maamaa ake te whakamatautau takitahi i ia ratonga, engari i tetahi atu taha, he hiahia ki te whakamatautau i te taunekeneke o nga ratonga ki a raatau ano, he maha nga wa ka puta i runga i te whatunga.
I roto i tenei tuhinga, ka korero ahau mo nga taputapu e rua ka taea te whakamahi ki te tirotiro i nga ahuatanga taketake e whakaatu ana i te mahi o tetahi tono i te aroaro o nga raruraru whatunga.
Te whakatauira i nga raru whatunga
I te nuinga o te waa, ka whakamatauria te rorohiko ki nga kaitoro whakamatautau me te hononga Ipurangi pai. I roto i nga taiao whakangao kino, kaore pea nga mea e tino maeneene, na i etahi wa ka hiahia koe ki te whakamatautau i nga kaupapa i roto i nga ahuatanga hononga ngoikore. I runga i te Linux, ka awhina te whaipainga ki te mahi whakatairite i enei ahuatanga tc.
tc(abbr. mai i te Mana Whakahaere) ka taea e koe te whirihora i te tukunga o nga paatete whatunga i roto i te punaha. He nui nga kaha o tenei taputapu, ka taea e koe te panui atu mo ratou . I konei ka whakaarohia e au etahi o enei: kei te pirangi matou ki te whakarite waka, e whakamahia ana e matou qdisc, a i te mea me whai tatou i te whatunga kore iu, ka whakamahia e tatou te qdisc kore-akomanga .
Ka whakarewahia e tatou he tūmau echo i runga i te tūmau (I whakamahia e ahau ):
ncat -l 127.0.0.1 12345 -k -c 'xargs -n1 -i echo "Response: {}"'
Hei whakaatu taipitopito i nga tohu wa katoa i ia taahiraa o te taunekeneke i waenga i te kiritaki me te tūmau, i tuhia e ahau he tuhinga Python ngawari ka tukuna he tono. whakamātautau ki to tatou tūmau echo.
Waehere puna kiritaki
#!/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
Kia whakarewahia ka titiro ki nga waka i runga i te atanga lo me te tauranga 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
Putunga waka
[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
Ko nga mea katoa he paerewa: he ringaringa e toru-ara, PSH / ACK me te ACK i te whakautu rua - koinei te whakawhitinga o te tono me te whakautu i waenga i te kiritaki me te tūmau, me te FIN / ACK me te ACK e rua - te whakaoti i te hononga.
Te roa o te kete
Inaianei ka tautuhia te whakaroa ki te 500 milihakona:
tc qdisc add dev lo root netem delay 500ms
Ka whakarewahia e matou te kiritaki ka kite kei te haere te tuhinga mo te 2 hēkona:
[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
He aha kei roto i te waka? Kia titiro tatou:
Putunga waka
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
Ka taea e koe te kite kua puta te takamuri e tumanakohia ana mo te hawhe hēkona i roto i te taunekeneke i waenga i te kiritaki me te tūmau. He pai ake te ahua o te punaha mena he nui ake te tamuri: ka timata te kernel ki te tuku ano i etahi paatete TCP. Me huri te whakaroa ki te 1 hēkona ka titiro ki te waka (Kaore au e whakaatu i te putanga a te kiritaki, kei reira nga 4 hēkona e tumanakohia ana mo te roanga katoa):
tc qdisc change dev lo root netem delay 1s
Putunga waka
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
Ka kitea e rua nga wa i tukuna e te kiritaki he putea SYN, ka tukuna e te tūmau he SYN/ACK rua.
I tua atu i te uara tonu, ka taea te whakarite i te whakaroa ki te rereke, te mahi tohatoha, me te hononga (me te uara mo te paatete o mua). Ka mahia tenei penei:
tc qdisc change dev lo root netem delay 500ms 400ms 50 distribution normal
I konei kua whakatauhia e matou te whakaroa i waenga i te 100 me te 900 milliseconds, ka kowhiria nga uara kia rite ki te tohatoha noa, ka 50% te hononga me te uara whakaroa mo te kete o mua.
Kua kite pea koe i te whakahau tuatahi i whakamahia e au tāpiriko reira hoki huringa. Ka kitea te tikanga o enei whakahau, no reira ka tapiri noa atu ahau he maha atu ano Tuhinga o mua, ka taea te whakamahi hei tango i te whirihoranga.
Ngaronga Pakete
Me ngana inaianei ki te mahi i te ngaronga paatete. Ka kitea mai i nga tuhinga, ka taea tenei ma nga huarahi e toru: te ngaro ohorere i nga paatete me te tupono noa, ma te whakamahi i te mekameka Markov e 2, 3, 4 ranei nga ahua ki te tatau i te ngaronga o te paatete, te whakamahi ranei i te tauira Elliott-Gilbert. I roto i te tuhinga ka whakaarohia e ahau te tikanga tuatahi (ngawari me te tino kitea), ka taea e koe te panui mo etahi atu .
Ka ngaro te 50% o nga paatete me te 25% te hononga:
tc qdisc add dev lo root netem loss 50% 25%
Engari, tcpdump e kore e kaha ki te whakaatu marama mai i te ngaronga o nga kete, ka whakaaro noa tatou he tino mahi. A, ko te piki haere me te kore o te waa whakahaere o te tuhinga ka awhina i a maatau ki te manatoko i tenei. kiritaki.py (ka taea te whakaoti inamata, i roto pea i te 20 hēkona), tae atu ki te pikinga ake o nga kete tuku ano:
[user@host ~]# netstat -s | grep retransmited; sleep 10; netstat -s | grep retransmited
17147 segments retransmited
17185 segments retransmited
Te taapiri haruru ki nga paatete
I tua atu i te ngaronga o te paatete, ka taea e koe te whakataurite i te kino o te paatete: ka puta te haruru ki te waahi o te paatete matapōkere. Kia kino te paakete me te 50% te tupono me te kore he hononga:
tc qdisc change dev lo root netem corrupt 50%
Ka whakahaerehia e matou te tuhinga a te kiritaki (kaore he mea whakamere i reira, engari e 2 hēkona te roa hei whakaoti), tirohia te waka:
Putunga waka
[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
Ka kitea he maha nga tukunga o etahi paakete, a, kotahi te paatete kua pakaru nga metadata: kōwhiringa [nop, unknown-65 0x0a3dcf62eb3d,[kōwhiri kino]>. Engari ko te mea nui ko te mutunga ka mahi tika nga mea katoa - i tutuki a TCP ki tana mahi.
Te tāruarua o te pākete
He aha atu ka taea e koe netem? Hei tauira, whakatairite i te ahuatanga whakamuri o te ngaronga o te paatete—te taarua o te paatete. E 2 hoki nga tohenga mo tenei whakahau: te tupono me te honohono.
tc qdisc change dev lo root netem duplicate 50% 25%
Te huri i te raupapa o nga kete
Ka taea e koe te whakakotahi i nga peke i nga huarahi e rua.
I te tuatahi, ka tukuna tonu etahi kete, ko te toenga me te whakaroa kua tohua. Tauira mai i te tuhinga:
tc qdisc change dev lo root netem delay 10ms reorder 25% 50%
Ki te 25% te tūponotanga (me te hononga o te 50%) ka tukuna tonu te kete, ko te toenga ka tukuna me te whakaroa 10 milliseconds.
Ko te tikanga tuarua ko te wa ka tukuna tonutia nga paakete Nth me te tuuponotanga (me te hononga), me te toenga me te whakaroa. Tauira mai i te tuhinga:
tc qdisc change dev lo root netem delay 10ms reorder 25% 50% gap 5
Ia rima o nga kete he 25% te tupono ka tukuna kia kaua e whakaroa.
Te huri i te Aratuku
I te nuinga o nga wa katoa e korero ana ratou , engari ma te awhina netem Ka taea hoki e koe te huri i te bandwidth atanga:
tc qdisc change dev lo root netem rate 56kbit
Ka hikoi haere tenei kapa localhost he mamae rite te ngaru i te Ipurangi ma te pouwhanga waea. I tua atu i te whakatakoto i te tere moka, ka taea hoki e koe te peehi i te tauira kawa paparanga hono: tautuhi i te upoko o runga mo te paatete, te rahi o te pūtau, me te runga ake mo te pūtau. Hei tauira, ka taea te whakataurite i tenei me te tere moka 56 kbit/hekona:
tc qdisc change dev lo root netem rate 56kbit 0 48 5
Te whakatairite i te waahi hononga
Ko tetahi atu mea nui i roto i te mahere whakamatautau i te wa e whakaae ana ki nga raupaparorohiko ko nga waahi. He mea nui tenei na te mea i roto i nga punaha toha, ka monokia tetahi o nga ratonga, me hoki ano etahi atu ki etahi atu i te waa, ka whakahoki mai ranei he hapa ki te kaihoko, kaua rawa e whakairi, tatari mo te whakautu, mo te hononga ranei kia whakapumautia.
He maha nga huarahi hei mahi i tenei: hei tauira, whakamahi i te tawai kaore i te whakautu, te hono ranei ki te tukanga ma te whakamahi i te patuiro, hoatu he waahi pakaru ki te waahi tika ka mutu te tukanga (koinei pea te huarahi tino kino). Engari ko tetahi o nga mea tino kitea ko nga tauranga papaahi, kaihautu ranei. Ka awhina i a maatau ki tenei .
Mo te whakaaturanga, ka tukuna e matou te tauranga papaahi 12345 ka whakahaere i ta matou tuhinga a te kiritaki. Ka taea e koe te paahi paahi puta atu ki tenei tauranga i te kaituku, i nga paanui taumai ranei i te kaiwhiwhi. I aku tauira, ka paahihia nga paatete taumai (ka whakamahi matou i te mekameka INPUT me te whiringa --dport). Ka taea e enei paakete te DROP, REJECT, REJECT ranei me te haki TCP RST, me te kaihautu ICMP kaore e taea te toro atu (he pono, ko te whanonga taunoa he icmp-tauranga-kore e taea te toro atu, kei reira hoki te whai waahi ki te tuku whakautu icmp-net-kore e taea te toro atu, icmp-proto-unreachable, icmp-kupenga-kore и icmp-kaihautu-kua rahuitia).
Mawehe
Mena he ture me DROP, ka "ngaro" noa nga paatete.
iptables -A INPUT -p tcp --dport 12345 -j DROP
Ka whakarewahia e matou te kaihoko me te kite kua whakatio i te wa e hono ana ki te tūmau. Kia titiro tatou ki te waka:
Putunga waka
[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
Ka kitea ka tukuna e te kiritaki nga paatete SYN me te wa e piki haere ana. Na ka kitea e matou he putea iti i roto i te kiritaki: me whakamahi koe i te tikanga tatū wā()hei whakawhāiti i te wā ka ngana te kiritaki ki te hono atu ki te tūmau.
Ka tangohia e matou te ture:
iptables -D INPUT -p tcp --dport 12345 -j DROPKa taea e koe te muku i nga ture katoa i te wa kotahi:
iptables -F
Mena kei te whakamahi koe i a Docker ka hiahia koe ki te paahi i nga waka katoa e haere ana ki te ipu, ka taea e koe te mahi penei:
iptables -I DOCKER-USER -p tcp -d CONTAINER_IP -j DROP
HE WHAKAMAHI
Inaianei ka taapirihia he ture rite, engari me REJECT:
iptables -A INPUT -p tcp --dport 12345 -j REJECT
Ka puta te kiritaki i muri i te hēkona me te hapa [Errno 111] I whakaae te hononga. Kia titiro tatou ki te hokohoko 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
Ka kitea e rua nga wa i whiwhi ai te kaihoko tauranga kore e taea te toro atu ka mutu he hapa.
WHAKAARO me tcp-tautuhi
Me ngana ki te taapiri i te whiringa --reject-with tcp-reset:
iptables -A INPUT -p tcp --dport 12345 -j REJECT --reject-with tcp-reset
I tenei keehi, ka puta tonu te kaihoko me te hapa, na te mea i whiwhi te tono tuatahi i te putea 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
WHAKAARO me te icmp-host-unreachable
Me whakamatau tetahi atu whiringa mo te whakamahi REJECT:
iptables -A INPUT -p tcp --dport 12345 -j REJECT --reject-with icmp-host-unreachable
Ka puta te kiritaki i muri i te hēkona me te hapa [Errno 113] Karekau he huarahi ki te manaaki, kite tatou i roto i te hokohoko ICMP ICMP ope 127.0.0.1 unreachable.
Ka taea hoki e koe te whakamatau i etahi atu tawhā REJECT, ka aro ahau ki enei :)
Te whakatairite i te waa tono
Ko tetahi atu ahuatanga ko te wa i taea e te kiritaki te hono atu ki te tūmau, engari kaore e taea te tuku tono ki a ia. Me pehea te tarai i nga paatete kia kore ai e timata tonu te tātari? Mena ka titiro koe ki te hokohoko o tetahi korero i waenga i te kiritaki me te tūmau, ka kite koe i te wa e whakatuu ana he hononga, ko nga haki SYN me te ACK anake ka whakamahia, engari i te wa e whakawhiti ana i nga raraunga, kei roto i te putea tono whakamutunga te haki PSH. Ka whakauruhia aunoa kia kore ai e paopao. Ka taea e koe te whakamahi i enei korero ki te hanga tātari: ka whakaaetia nga paanui katoa engari ko nga mea kei roto te haki PSH. Na, ka whakapumautia te hononga, engari kaore e taea e te kiritaki te tuku raraunga ki te tūmau.
Mawehe
Mo te DROP ka penei te ahua o te whakahau:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j DROP
Whakarewahia te kiritaki me te mataki i nga waka:
Putunga waka
[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
Ka kite matou kua whakapumautia te hononga me te kore e taea e te kiritaki te tuku raraunga ki te tūmau.
HE WHAKAMAHI
I tenei keehi ka rite te whanonga: kaore e taea e te kiritaki te tuku tono, engari ka whiwhi ICMP 127.0.0.1 tcp tauranga 12345 kore e taea me te whakanui ake i te wa i waenga i nga tono tukunga tono. He penei te ahua o te whakahau:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j REJECT
WHAKAARO me tcp-tautuhi
He penei te ahua o te whakahau:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j REJECT --reject-with tcp-reset
Kua mohio tatou i te wa e whakamahi ana --reject-with tcp-reset ka whiwhi te kiritaki i te putea RST hei whakautu, na reira ka taea te matapae i te whanonga: te whiwhi i te putea RST i te wa e tau ana te hononga, ko te tikanga ka kati ohorere te turanga ki tera taha, ko te tikanga me whiwhi te kaihoko Tautuhi hononga ma te hoa. Me whakahaere ta maatau tuhinga me te whakarite i tenei. A koinei te ahua o te waka:
Putunga waka
[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
WHAKAARO me te icmp-host-unreachable
Ki taku whakaaro kua tino kitea e te katoa te ahua o te whakahau :) Ko te whanonga o te kiritaki i tenei keehi ka rereke te rereke mai i tera me te WHAKAARO ngawari: kaore te kaihoko e whakanui i te wa i waenga i nga ngana ki te tuku ano i te kete.
[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
mutunga
Ehara i te mea tika ki te tuhi i te tawai ki te whakamatautau i te taunekeneke o tetahi ratonga me te kaihoko whakairihia ranei, i etahi wa ka nui ki te whakamahi i nga taputapu paerewa e kitea ana i Linux.
Ko nga taputapu e korerohia ana i roto i te tuhinga he nui ake nga kaha i nga korero i whakaahuahia, na ka taea e koe te whakaputa etahi o au ake whiringa mo te whakamahi. Ko ahau ake, kei a au tonu nga mea i tuhia e au (i roto i te meka, he iti noa iho). Mena kei te whakamahi koe i enei taputapu rite ranei ki te whakamatautau i to kamupene, tuhia koa me pehea. Mena kaore, ka tumanako ahau ka pai ake to rorohiko mena ka whakatau koe ki te whakamatau i nga raru o te whatunga ma te whakamahi i nga tikanga kua tohua.
Source: will.com