Kaabo gbogbo eniyan, orukọ mi ni Sasha, Mo ṣe itọsọna idanwo ẹhin ni FunCorp. A, bii ọpọlọpọ awọn miiran, ti ṣe imuse faaji ti o da lori iṣẹ. Ni ọna kan, eyi jẹ ki iṣẹ naa rọrun, nitori ... O rọrun lati ṣe idanwo iṣẹ kọọkan lọtọ, ṣugbọn ni apa keji, iwulo wa lati ṣe idanwo ibaraenisepo awọn iṣẹ pẹlu ara wọn, eyiti o waye nigbagbogbo lori nẹtiwọọki.
Ninu àpilẹkọ yii, Emi yoo sọrọ nipa awọn ohun elo meji ti o le ṣee lo lati ṣayẹwo awọn oju iṣẹlẹ ipilẹ ti o ṣe apejuwe iṣẹ ti ohun elo ni iwaju awọn iṣoro nẹtiwọki.
Simulating nẹtiwọki isoro
Ni deede, sọfitiwia ni idanwo lori awọn olupin idanwo pẹlu asopọ Intanẹẹti to dara. Ni awọn agbegbe iṣelọpọ lile, awọn nkan le ma jẹ dan, nitorinaa nigbami o nilo lati ṣe idanwo awọn eto ni awọn ipo asopọ ti ko dara. Lori Lainos, ohun elo naa yoo ṣe iranlọwọ pẹlu iṣẹ ṣiṣe simulating iru awọn ipo tc.
tc(abbr. lati Iṣakoso ijabọ) faye gba o lati tunto awọn gbigbe ti nẹtiwọki awọn apo-iwe ninu awọn eto. IwUlO yii ni awọn agbara nla, o le ka diẹ sii nipa wọn . Nibi Emi yoo ṣe akiyesi diẹ diẹ ninu wọn: a nifẹ si ṣiṣe eto ijabọ, fun eyiti a lo qdisc, ati pe niwọn igba ti a nilo lati ṣe apẹẹrẹ nẹtiwọọki aiduro, a yoo lo qdisc alailẹgbẹ .
Jẹ ki a ṣe ifilọlẹ olupin iwoyi lori olupin naa (Mo lo ):
ncat -l 127.0.0.1 12345 -k -c 'xargs -n1 -i echo "Response: {}"'
Lati le ṣafihan ni awọn alaye ni kikun gbogbo awọn aami akoko ni igbesẹ kọọkan ti ibaraenisepo laarin alabara ati olupin naa, Mo kọ iwe afọwọkọ Python ti o rọrun kan ti o firanṣẹ ibeere kan igbeyewo si olupin iwoyi wa.
Klient orisun koodu
#!/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
Jẹ ká lọlẹ o ati ki o wo ni awọn ijabọ lori wiwo lo ati ibudo 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
Idasonu ijabọ
[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
Ohun gbogbo jẹ boṣewa: ọwọ ọwọ-ọna mẹta, PSH / ACK ati ACK ni idahun lẹẹmeji - eyi ni paṣipaarọ ibeere ati idahun laarin alabara ati olupin, ati FIN / ACK ati ACK lẹmeji - ipari asopọ naa.
Idaduro apo
Bayi jẹ ki a ṣeto idaduro si 500 milliseconds:
tc qdisc add dev lo root netem delay 500ms
A ṣe ifilọlẹ alabara ati rii pe iwe afọwọkọ bayi nṣiṣẹ fun awọn aaya 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
Kini o wa ninu ijabọ? Jẹ ki a wo:
Idasonu ijabọ
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
O le rii pe aisun ti a nireti ti idaji iṣẹju kan ti han ninu ibaraenisepo laarin alabara ati olupin naa. Eto naa ṣe ihuwasi pupọ diẹ sii ti aisun ba tobi: ekuro bẹrẹ lati firanṣẹ diẹ ninu awọn apo-iwe TCP. Jẹ ki a yi idaduro pada si iṣẹju 1 ki o wo ijabọ naa (Emi kii yoo ṣe afihan iṣẹjade ti alabara, awọn aaya 4 ti a nireti ni iye akoko lapapọ):
tc qdisc change dev lo root netem delay 1s
Idasonu ijabọ
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
O le wa ni ri pe awọn ose rán a SYN soso lemeji, ati awọn olupin rán a SYN/ACK lemeji.
Ni afikun si iye igbagbogbo, idaduro le ṣee ṣeto si iyapa, iṣẹ pinpin, ati ibamu (pẹlu iye fun apo-iwe ti tẹlẹ). Eyi ni a ṣe bi atẹle:
tc qdisc change dev lo root netem delay 500ms 400ms 50 distribution normal
Nibi a ti ṣeto idaduro laarin 100 ati 900 milliseconds, awọn iye yoo yan ni ibamu si pinpin deede ati pe yoo wa ni ibamu 50% pẹlu iye idaduro fun soso ti tẹlẹ.
O le ti ṣe akiyesi pe ni aṣẹ akọkọ ti Mo lo fi, ati igba yen ayipada. Itumọ ti awọn aṣẹ wọnyi han, nitorinaa Emi yoo ṣafikun pe diẹ sii wa del, eyi ti o le ṣee lo lati yọ iṣeto ni.
Packet Isonu
Jẹ ki a ni bayi gbiyanju lati ṣe pipadanu soso. Gẹgẹbi a ti le rii lati inu iwe, eyi le ṣee ṣe ni awọn ọna mẹta: sisọnu awọn apo-iwe laileto pẹlu iṣeeṣe diẹ, lilo ẹwọn Markov ti 2, 3 tabi 4 awọn ipinlẹ lati ṣe iṣiro pipadanu apo, tabi lilo awoṣe Elliott-Gilbert. Ninu nkan naa Emi yoo ṣe akiyesi ọna akọkọ (rọrun ati han julọ), ati pe o le ka nipa awọn miiran .
Jẹ ki a ṣe isonu ti 50% ti awọn apo-iwe pẹlu ibamu ti 25%:
tc qdisc add dev lo root netem loss 50% 25%
Laanu, tcpdump kii yoo ni anfani lati fihan gbangba isonu ti awọn apo-iwe, a yoo ro pe o ṣiṣẹ gaan. Ati pe akoko ṣiṣe ti o pọ si ati riru ti iwe afọwọkọ yoo ran wa lọwọ lati rii daju eyi. onibara.py (le ti pari lesekese, tabi boya ni iṣẹju-aaya 20), bakanna bi nọmba ti o pọ si ti awọn apo-iwe ti a tun gbejade:
[user@host ~]# netstat -s | grep retransmited; sleep 10; netstat -s | grep retransmited
17147 segments retransmited
17185 segments retransmited
Fifi ariwo si awọn apo-iwe
Ni afikun si ipadanu soso, o le ṣedasilẹ ibajẹ apo-iwe: ariwo yoo han ni ipo idii laileto. Jẹ ki a ṣe ibajẹ soso pẹlu iṣeeṣe 50% ati laisi ibamu:
tc qdisc change dev lo root netem corrupt 50%
A nṣiṣẹ iwe afọwọkọ alabara (ko si ohun ti o nifẹ sibẹ, ṣugbọn o gba iṣẹju-aaya 2 lati pari), wo ijabọ naa:
Idasonu ijabọ
[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
O le rii pe diẹ ninu awọn apo-iwe ni a firanṣẹ leralera ati pe apo kan wa pẹlu metadata ti o fọ: awọn aṣayan [nop, aimọ-65 0x0a3dcf62eb3d,[buburu ijade]>. Ṣugbọn ohun akọkọ ni pe ni ipari ohun gbogbo ṣiṣẹ ni deede - TCP farada pẹlu iṣẹ-ṣiṣe rẹ.
Apo-pada
Kini ohun miiran ti o le se pẹlu netem? Fun apẹẹrẹ, ṣe afiwe ipo iyipada ti ipadanu apo-iwe-pipọkọ. Aṣẹ yii tun gba awọn ariyanjiyan 2: iṣeeṣe ati ibamu.
tc qdisc change dev lo root netem duplicate 50% 25%
Yiyipada aṣẹ ti awọn idii
O le dapọ awọn apo ni awọn ọna meji.
Ni akọkọ, diẹ ninu awọn apo-iwe ni a firanṣẹ lẹsẹkẹsẹ, iyokù pẹlu idaduro pàtó kan. Apẹẹrẹ lati inu iwe-ipamọ naa:
tc qdisc change dev lo root netem delay 10ms reorder 25% 50%
Pẹlu iṣeeṣe ti 25% (ati ibamu ti 50%) apo naa yoo firanṣẹ lẹsẹkẹsẹ, iyokù yoo firanṣẹ pẹlu idaduro ti 10 milliseconds.
Ọna keji jẹ nigbati gbogbo apo Nth ti firanṣẹ lẹsẹkẹsẹ pẹlu iṣeeṣe ti a fun (ati ibamu), ati iyokù pẹlu idaduro ti a fun. Apẹẹrẹ lati inu iwe-ipamọ naa:
tc qdisc change dev lo root netem delay 10ms reorder 25% 50% gap 5
Gbogbo karun package ni o ni a 25% anfani to a firanṣẹ lai idaduro.
Iyipada bandiwidi
Nigbagbogbo nibikibi ti wọn tọka si , ṣugbọn pẹlu iranlọwọ netem O tun le yi bandiwidi wiwo pada:
tc qdisc change dev lo root netem rate 56kbit
Ẹgbẹ yii yoo ṣe awọn irin-ajo ni ayika localhost bi irora bi lilọ kiri lori Intanẹẹti nipasẹ modẹmu kiakia. Ni afikun si tito bitrate, o tun le ṣe apẹẹrẹ awoṣe ilana Layer Layer: ṣeto oke fun apo, iwọn sẹẹli, ati oke fun sẹẹli naa. Fun apẹẹrẹ, eyi le ṣe adaṣe ati bitrate 56 kbit/iseju:
tc qdisc change dev lo root netem rate 56kbit 0 48 5
Simulating asopọ akoko ipari
Ojuami pataki miiran ninu ero idanwo nigbati gbigba sọfitiwia jẹ awọn akoko ipari. Eyi ṣe pataki nitori ni awọn eto pinpin, nigbati ọkan ninu awọn iṣẹ naa ba jẹ alaabo, awọn miiran gbọdọ ṣubu si awọn miiran ni akoko tabi da aṣiṣe pada si alabara, ati pe ni ọran kankan ko yẹ ki wọn gbele, nduro fun esi tabi asopọ kan. lati wa ni idasilẹ.
Awọn ọna pupọ lo wa lati ṣe eyi: fun apẹẹrẹ, lo ẹgan ti ko dahun, tabi sopọ si ilana nipa lilo olutọpa kan, fi aaye fifọ si aaye ti o tọ ki o da ilana naa duro (eyi ṣee ṣe ọna ti o yipada julọ). Ṣugbọn ọkan ninu awọn julọ han ni lati ogiriina ebute oko tabi ogun. Yoo ṣe iranlọwọ fun wa pẹlu eyi .
Fun ifihan, a yoo ibudo ogiriina 12345 ati ṣiṣe iwe afọwọkọ alabara wa. O le awọn apo-iwe ti njade ogiriina si ibudo yii ni olufiranṣẹ tabi awọn apo-iwe ti nwọle ni olugba. Ninu awọn apẹẹrẹ mi, awọn apo-iwe ti nwọle yoo jẹ ogiriina (a lo INPUT pq ati aṣayan -- idaraya). Iru awọn apo-iwe bẹ le jẹ DROP, REJECT tabi REJECT pẹlu asia TCP RST, tabi pẹlu alejo gbigba ICMP ti ko le de ọdọ (ni otitọ, ihuwasi aiyipada jẹ icmp-ibudo-ti ko le de ọdọ, ati nibẹ ni tun ni anfani lati a fi esi icmp-net-ti ko le de ọdọ, icmp-proto-kò lè dé, icmp-net- eewọ и icmp-ogun-eewọ).
JU
Ti ofin ba wa pẹlu DROP, awọn apo-iwe yoo “parun”.
iptables -A INPUT -p tcp --dport 12345 -j DROP
A ṣe ifilọlẹ alabara ati rii pe o didi ni ipele ti sisopọ si olupin naa. Jẹ ki a wo ijabọ:
Idasonu ijabọ
[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
O le rii pe alabara nfi awọn apo-iwe SYN ranṣẹ pẹlu akoko akoko ti n pọ si lọpọlọpọ. Nitorinaa a rii kokoro kekere kan ninu alabara: o nilo lati lo ọna naa akoko idaduro()lati se idinwo akoko nigba ti ose yoo gbiyanju lati sopọ si olupin.
A yọ ofin kuro lẹsẹkẹsẹ:
iptables -D INPUT -p tcp --dport 12345 -j DROPO le pa gbogbo awọn ofin rẹ ni ẹẹkan:
iptables -F
Ti o ba nlo Docker ati pe o nilo lati ogiriina gbogbo awọn ijabọ ti n lọ si eiyan, lẹhinna o le ṣe bi atẹle:
iptables -I DOCKER-USER -p tcp -d CONTAINER_IP -j DROP
RỌRUN
Bayi jẹ ki a ṣafikun ofin ti o jọra, ṣugbọn pẹlu REJECT:
iptables -A INPUT -p tcp --dport 12345 -j REJECT
Onibara jade lẹhin iṣẹju-aaya pẹlu aṣiṣe kan [Aṣiṣe 111] Asopọ kọ. Jẹ ki a wo ijabọ 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
O le rii pe alabara gba lẹmeji ibudo unreachable ati lẹhinna pari pẹlu aṣiṣe kan.
REJECT pẹlu tcp-tunto
Jẹ ká gbiyanju lati fi awọn aṣayan --kọ-pẹlu tcp-tunto:
iptables -A INPUT -p tcp --dport 12345 -j REJECT --reject-with tcp-reset
Ni ọran yii, alabara yoo jade lẹsẹkẹsẹ pẹlu aṣiṣe kan, nitori ibeere akọkọ gba apo-iwe RST kan:
[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
REJECT pẹlu icmp-ogun-a ko le de ọdọ
Jẹ ki a gbiyanju aṣayan miiran fun lilo REJECT:
iptables -A INPUT -p tcp --dport 12345 -j REJECT --reject-with icmp-host-unreachable
Onibara jade lẹhin iṣẹju-aaya pẹlu aṣiṣe kan [Aṣiṣe 113] Ko si ipa-ọna lati gbalejo, a rii ni ijabọ ICMP ICMP ogun 127.0.0.1 unreachable.
O tun le gbiyanju awọn paramita REJECT miiran, ati pe Emi yoo dojukọ awọn wọnyi :)
Simulating ìbéèrè akoko ipari
Ipo miiran jẹ nigbati alabara ni anfani lati sopọ si olupin, ṣugbọn ko le fi ibeere ranṣẹ si. Bawo ni lati ṣe àlẹmọ awọn apo-iwe ki sisẹ ko bẹrẹ lẹsẹkẹsẹ? Ti o ba wo ijabọ eyikeyi ibaraẹnisọrọ laarin alabara ati olupin, iwọ yoo ṣe akiyesi pe nigbati o ba ṣeto asopọ kan, awọn asia SYN ati ACK nikan ni a lo, ṣugbọn nigbati o ba paarọ data, apo-iwe ibeere ti o kẹhin yoo ni asia PSH. O nfi sori ẹrọ laifọwọyi lati yago fun ifipamọ. O le lo alaye yii lati ṣẹda àlẹmọ: yoo gba gbogbo awọn apo-iwe laaye ayafi awọn ti o ni asia PSH ninu. Nitorinaa, asopọ naa yoo fi idi mulẹ, ṣugbọn alabara kii yoo ni anfani lati fi data ranṣẹ si olupin naa.
JU
Fun DROP aṣẹ yoo dabi eyi:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j DROP
Lọlẹ alabara ki o wo ijabọ naa:
Idasonu ijabọ
[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
A rii pe asopọ ti wa ni idasilẹ ati alabara ko le fi data ranṣẹ si olupin naa.
RỌRUN
Ni idi eyi ihuwasi yoo jẹ kanna: alabara kii yoo ni anfani lati firanṣẹ ibeere naa, ṣugbọn yoo gba ICMP 127.0.0.1 tcp ibudo 12345 ko le de ọdọ ati mu akoko pọ si laarin awọn ifisilẹ ibeere ni afikun. Aṣẹ naa dabi eyi:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j REJECT
REJECT pẹlu tcp-tunto
Aṣẹ naa dabi eyi:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j REJECT --reject-with tcp-reset
A ti mọ tẹlẹ nigba lilo --kọ-pẹlu tcp-tunto alabara yoo gba apo-iwe RST kan ni idahun, nitorinaa ihuwasi naa le jẹ asọtẹlẹ: gbigba apo-iwe RST kan lakoko ti asopọ ti fi idi mulẹ tumọ si iho naa ti wa ni pipade lairotẹlẹ ni apa keji, eyiti o tumọ si pe alabara yẹ ki o gba. Atunto asopọ nipasẹ ẹlẹgbẹ. Jẹ ki a ṣiṣẹ iwe afọwọkọ wa ki o rii daju eyi. Ati pe eyi ni ohun ti ijabọ yoo dabi:
Idasonu ijabọ
[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
REJECT pẹlu icmp-ogun-a ko le de ọdọ
Mo ro pe o ti han tẹlẹ fun gbogbo eniyan kini aṣẹ naa yoo dabi :) Iwa ihuwasi ti alabara ninu ọran yii yoo jẹ iyatọ diẹ si iyẹn pẹlu REJECT ti o rọrun: alabara kii yoo mu akoko ipari laarin awọn igbiyanju lati tun soso naa pada.
[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
ipari
Ko ṣe pataki lati kọ ẹgan lati ṣe idanwo ibaraenisepo ti iṣẹ kan pẹlu alabara ti a fikọ tabi olupin; nigbakan o to lati lo awọn ohun elo boṣewa ti a rii ni Linux.
Awọn ohun elo ti a sọrọ ninu nkan naa paapaa ni awọn agbara diẹ sii ju ti a ṣalaye lọ, nitorinaa o le wa diẹ ninu awọn aṣayan tirẹ fun lilo wọn. Tikalararẹ, Mo nigbagbogbo ni to ti ohun ti Mo kọ nipa (ni otitọ, paapaa kere si). Ti o ba lo iwọnyi tabi awọn ohun elo ti o jọra ni idanwo ni ile-iṣẹ rẹ, jọwọ kọ bii gangan. Ti kii ba ṣe bẹ, lẹhinna Mo nireti pe sọfitiwia rẹ yoo dara julọ ti o ba pinnu lati ṣe idanwo ni awọn ipo ti awọn iṣoro nẹtiwọọki nipa lilo awọn ọna ti a daba.
orisun: www.habr.com