Ndewo onye ọ bụla, aha m bụ Sasha, ana m eduzi ule azụ azụ na FunCorp. Anyị, dị ka ọtụtụ ndị ọzọ, emejuputala ihe owuwu nke dabere na ọrụ. N'otu aka ahụ, nke a na-eme ka ọrụ ahụ dị mfe, n'ihi na ... Ọ dị mfe ịnwale ọrụ ọ bụla iche iche, ma n'aka nke ọzọ, ọ dị mkpa iji nwalee mmekọrịta nke ọrụ na ibe ya, nke na-emekarị na netwọk.
N'isiokwu a, m ga-ekwu maka ọrụ abụọ nwere ike iji lelee ọnọdụ ndị bụ isi na-akọwa ọrụ nke ngwa n'ihu nsogbu netwọkụ.
Ịmepụta nsogbu netwọkụ
Dịka, a na-anwale ngwanrọ na sava ule nwere ezigbo njikọ ịntanetị. Na gburugburu mmepụta ihe siri ike, ihe nwere ike ọ gaghị adị mma, yabụ mgbe ụfọdụ ịkwesịrị ịnwale mmemme na ọnọdụ njikọ adịghị mma. Na Linux, akụrụngwa ga-enyere aka na ọrụ ịmegharị ọnọdụ ndị dị otú ahụ tc.
tc(abbr. site na njikwa okporo ụzọ) na-enye gị ohere ịhazi nnyefe nke ngwugwu netwọk na usoro. Ngwa a nwere ikike dị ukwuu, ị nwere ike ịgụkwu gbasara ha . N'ebe a, m ga-atụle naanị ole na ole n'ime ha: anyị nwere mmasị na nhazi usoro okporo ụzọ, nke anyị na-eji qdisc, na ebe ọ bụ na anyị kwesịrị iṅomi netwọk na-adịghị akwụ ụgwọ, anyị ga-eji qdisc na-enweghị klas .
Ka anyị malite ihe nkesa echo na ihe nkesa (m jiri ):
ncat -l 127.0.0.1 12345 -k -c 'xargs -n1 -i echo "Response: {}"'
Iji gosipụta n'ụzọ zuru ezu ihe niile stampụ oge na nzọụkwụ ọ bụla nke mmekọrịta dị n'etiti onye ahịa na ihe nkesa, edere m edemede Python dị mfe nke na-eziga arịrịọ. ule na nkesa echo anyị.
Koodu isi mmalite ndị ahịa
#!/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
Ka ẹkedori ya na anya na okporo ụzọ na interface lo na ọdụ ụgbọ mmiri 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
Mkpofu okporo ụzọ
[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
Ihe niile bụ ọkọlọtọ: aka aka atọ, PSH / ACK na ACK na nzaghachi ugboro abụọ - nke a bụ mgbanwe nke arịrịọ na nzaghachi n'etiti onye ahịa na ihe nkesa, na FIN / ACK na ACK ugboro abụọ - imecha njikọ ahụ.
Ngwugwu igbu oge
Ugbu a, ka anyị tọọ igbu oge na 500 millise seconds:
tc qdisc add dev lo root netem delay 500ms
Anyị na-ebupụta onye ahịa ahụ wee hụ na edemede ahụ na-agba ọsọ maka 2 sekọnd:
[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
Kedu ihe dị na okporo ụzọ? Ka anyị lee:
Mkpofu okporo ụzọ
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
Ị nwere ike ịhụ na njedebe a na-atụ anya na ọkara nke abụọ apụtala na mmekọrịta dị n'etiti onye ahịa na ihe nkesa. Sistemu ahụ na-eme ihe na-atọ ụtọ karị ma ọ bụrụ na lag ahụ ka ukwuu: kernel na-amalite iziga ụfọdụ ngwugwu TCP. Ka anyị gbanwee igbu oge ka ọ bụrụ 1 sekọnd wee lelee okporo ụzọ (Agaghị m egosi mmepụta nke onye ahịa, enwere 4 sekọnd a tụrụ anya na ngụkọta oge):
tc qdisc change dev lo root netem delay 1s
Mkpofu okporo ụzọ
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
Enwere ike ịhụ na onye ahịa ahụ zigara ngwugwu SYN ugboro abụọ, na ihe nkesa zitere SYN/ACK ugboro abụọ.
Na mgbakwunye na uru na-adịgide adịgide, enwere ike ịtọ oge igbu oge na ntụgharị, ọrụ nkesa, na njikọ (ya na uru maka ngwugwu gara aga). A na-eme nke a dị ka ndị a:
tc qdisc change dev lo root netem delay 500ms 400ms 50 distribution normal
N'ebe a, anyị edobela igbu oge n'etiti 100 na 900 milliseconds, a ga-ahọrọ ụkpụrụ dịka nkesa nkịtị si dị, a ga-enwekwa mmekọrịta 50% na uru igbu oge maka ngwugwu gara aga.
O nwere ike ịbụ na ị chọpụtala na n'iwu mbụ m ji mee ihe tinye, Ọzọkwa mgbanwe. Ihe iwu ndị a pụtara doro anya, yabụ m ga-agbakwunye na enwere karịa na, nke enwere ike iji wepụ nhazi ahụ.
Mfu ngwugwu
Ka anyị gbalịa ugbu a ime mfu ngwugwu. Dị ka a na-ahụ na akwụkwọ ahụ, enwere ike ime nke a n'ụzọ atọ: na-efunahụ ngwugwu na-enweghị usoro na ụfọdụ ihe gbasara nke puru omume, na-eji agbụ Markov nke 2, 3 ma ọ bụ 4 steeti iji gbakọọ mfu ngwugwu, ma ọ bụ iji ụdị Elliott-Gilbert. N'isiokwu ahụ, m ga-atụle usoro mbụ (dị mfe na nke doro anya), ma ị nwere ike ịgụ banyere ndị ọzọ .
Ka anyị mee mfu nke 50% nke ngwugwu yana njikọ nke 25%:
tc qdisc add dev lo root netem loss 50% 25%
O di nwute, cma agaghị enwe ike igosi anyị n'ụzọ doro anya ọnwụ nke ngwugwu, anyị ga-eche na ọ na-arụ ọrụ n'ezie. Na oge na-agba ọsọ na-adịghị akwụsị akwụsị nke edemede ahụ ga-enyere anyị aka ịchọpụta nke a. onye ahịa.py (enwere ike mechaa ozugbo, ma ọ bụ ikekwe na 20 sekọnd), yana ọnụ ọgụgụ abawanyela nke ngwugwu ebugharị:
[user@host ~]# netstat -s | grep retransmited; sleep 10; netstat -s | grep retransmited
17147 segments retransmited
17185 segments retransmited
Na-agbakwụnye mkpọtụ na ngwugwu
Na mgbakwunye na mfu ngwugwu, ị nwere ike ịmegharị mmebi ngwugwu: mkpọtụ ga-apụta na ọnọdụ ngwugwu enweghị usoro. Ka anyị jiri ohere 50% mebie ngwugwu na enweghị njikọ:
tc qdisc change dev lo root netem corrupt 50%
Anyị na-agba akwụkwọ edemede ndị ahịa (ọ nweghị ihe na-adọrọ mmasị ebe ahụ, mana ọ were 2 sekọnd iji wuchaa), lelee okporo ụzọ:
Mkpofu okporo ụzọ
[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
Enwere ike ịhụ na ezigara ụfọdụ ngwugwu ugboro ugboro ma enwere otu ngwugwu nwere metadata gbajiri agbaji: nhọrọ [nop, amaghị-65 0x0a3dcf62eb3d,[ọjọọ nhọrọ]>. Ma isi ihe bụ na n'ikpeazụ ihe niile na-arụ ọrụ nke ọma - TCP nagidere ya ọrụ.
Ntugharị ngwugwu
Kedu ihe ọzọ ị nwere ike iji netem? Dịka ọmụmaatụ, mee ka ọnọdụ ntụgharị nke mfu ngwugwu—mbigharị ngwugwu. Iwu a na-ewekwa arụmụka 2: ihe gbasara nke puru omume na mmekorita.
tc qdisc change dev lo root netem duplicate 50% 25%
Ịgbanwe usoro ngwugwu
Ị nwere ike ịgwakọta akpa ahụ n'ụzọ abụọ.
Na nke mbụ, a na-eziga ụfọdụ ngwugwu ozugbo, ndị ọzọ nwere oge a kapịrị ọnụ. Ọmụmaatụ sitere na akwụkwọ:
tc qdisc change dev lo root netem delay 10ms reorder 25% 50%
Site na ihe gbasara nke 25% (na njikọ nke 50%) a ga-eziga ngwugwu ahụ ozugbo, a ga-eziga ndị ọzọ na nkwụsị nke 10 milliseconds.
Usoro nke abụọ bụ mgbe ezipu ngwugwu Nth ọ bụla ozugbo yana ohere enyere (na njikọ), ndị ọzọ nwere oge oge. Ọmụmaatụ sitere na akwụkwọ:
tc qdisc change dev lo root netem delay 10ms reorder 25% 50% gap 5
Ngwungwu ise ọ bụla nwere ohere izipu 25% n'egbughị oge.
Na-agbanwe bandwit
Na-emekarị n'ebe ọ bụla ha na-ezo aka , ma site n'enyemaka netem Ị nwekwara ike ịgbanwe bandwidth interface:
tc qdisc change dev lo root netem rate 56kbit
Otu a ga-eme njem gburugburu localhost na-egbu mgbu dị ka ịgagharị ịntanetị site na modem ọkpụkpọ. Na mgbakwunye na ịtọlite bitrate, ị nwekwara ike iṅomi ụdị njikọ oyi akwa: tọọ isi maka ngwugwu ahụ, nha cell, na isi maka cell. Dịka ọmụmaatụ, enwere ike ịme nke a na bitrate 56 kbit/sk:
tc qdisc change dev lo root netem rate 56kbit 0 48 5
N'ịtụgharị oge njikọ
Ihe ọzọ dị mkpa na atụmatụ ule mgbe ị na-anabata ngwanrọ bụ oge nkwụsị. Nke a dị mkpa n'ihi na na sistemụ kesara, mgbe otu n'ime ọrụ ahụ nwere nkwarụ, ndị ọzọ ga-adaghachi na ndị ọzọ n'oge ma ọ bụ weghachi onye ahịa ahụ njehie, na ọ nweghị ikpe ha ga-ekudo, na-eche nzaghachi ma ọ bụ njikọ. a ga-eguzobe.
Enwere ụzọ dị iche iche isi mee nke a: dịka ọmụmaatụ, jiri njakịrị na-adịghị azaghachi, ma ọ bụ jikọọ na usoro site na iji debugger, tinye nkwụsịtụ n'ebe kwesịrị ekwesị ma kwụsị usoro ahụ (nke a bụ eleghị anya ụzọ kachasị agbagọ). Mana otu n'ime ihe doro anya bụ ọdụ ụgbọ mmiri ma ọ bụ ndị ọbịa. Ọ ga-enyere anyị aka na nke a .
Maka ngosipụta, anyị ga-emepe ọdụ ụgbọ mmiri 12345 ma na-agba akwụkwọ edemede ndị ahịa anyị. Ị nwere ike ịnweta ngwugwu ọkụ na-apụ apụ na ọdụ ụgbọ mmiri a na onye na-ezigara ma ọ bụ ngwugwu na-abata na nnata. N'ihe atụ m, ngwugwu na-abata ga-agbanyụ ọkụ (anyị na-eji yinye INPUT na nhọrọ --dport). Ụdị ngwugwu ndị a nwere ike ịbụ DROP, REJECT ma ọ bụ JỤRỤ na ọkọlọtọ TCP RST, ma ọ bụ ya na ndị ọbịa ICMP enweghị ike ịnweta (n'ezie, omume ndabara bụ icmp-ọdụ ụgbọ mmiri-apụghị iru, na enwekwara ohere izipu azịza icmp-net-enweghị ike iru, icmp-proto-enweghị ike iru, icmp-net-amachibidoro и icmp-onye ọbịa-amachibidoro).
DARA
Ọ bụrụ na enwere iwu na DROP, ngwugwu ga-apụ naanị.
iptables -A INPUT -p tcp --dport 12345 -j DROP
Anyị na-ebupụta onye ahịa wee hụ na ọ na-agbaze na ọkwa nke ijikọ na ihe nkesa ahụ. Ka anyị lelee okporo ụzọ:
Mkpofu okporo ụzọ
[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
Enwere ike ịhụ na onye ahịa na-eziga ngwugwu SYN na oge nkwụsị na-abawanye ụba. Ya mere, anyị chọtara obere ahụhụ na onye ahịa: ịkwesịrị iji usoro ahụ oge nkwụsị ()iji belata oge nke onye ahịa ga-agbalị ijikọ na ihe nkesa.
Anyị na-ewepụ iwu ozugbo:
iptables -D INPUT -p tcp --dport 12345 -j DROPỊ nwere ike ihichapụ iwu niile ozugbo:
iptables -F
Ọ bụrụ na ị na-eji Docker ma ịchọrọ ịgbanye okporo ụzọ niile na-aga akpa, ị nwere ike ime ya dị ka ndị a:
iptables -I DOCKER-USER -p tcp -d CONTAINER_IP -j DROP
J .R.
Ugbu a, ka anyị gbakwunye otu iwu, mana jiri REJECT:
iptables -A INPUT -p tcp --dport 12345 -j REJECT
Onye ahịa na-apụ ma ọ gafesịrị nkeji nkeji yana mperi [Errno 111] Njikọ jụrụ. Ka anyị lelee okporo ụzọ 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
Enwere ike ịhụ na onye ahịa natara ugboro abụọ ọdụ ụgbọ mmiri enweghị ike iru wee jiri njehie mechie.
Jụgharịa na tcp-tọgharịa
Ka anyị gbalịa ịgbakwunye nhọrọ --ajụ-na tcp-tọgharịa:
iptables -A INPUT -p tcp --dport 12345 -j REJECT --reject-with tcp-reset
N'okwu a, onye ahịa na-apụ ozugbo na njehie, n'ihi na arịrịọ mbụ natara ngwugwu 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
Jụọ ya na icmp-host-enweghị ike iru ya
Ka anyị nwaa nhọrọ ọzọ maka iji REJECT:
iptables -A INPUT -p tcp --dport 12345 -j REJECT --reject-with icmp-host-unreachable
Onye ahịa na-apụ ma ọ gafesịrị nkeji nkeji yana mperi [Errno 113] Enweghị ụzọ ị ga-esi nweta nnabata, anyị na-ahụ na okporo ụzọ ICMP Ndị ọbịa ICMP 127.0.0.1 enweghị ike iru.
Ị nwekwara ike ịnwale paramita REJECT ndị ọzọ, m ga-elekwasị anya na ndị a :)
N'ịkwalite arịrịọ agwụla
Ọnọdụ ọzọ bụ mgbe onye ahịa nwere ike jikọọ na ihe nkesa, mana enweghị ike izipu arịrịọ na ya. Kedu ka esi enyocha ngwugwu ka nzacha ghara ịmalite ozugbo? Ọ bụrụ na ị na-elele okporo ụzọ nke nkwurịta okwu ọ bụla n'etiti onye ahịa na ihe nkesa, ị ga-achọpụta na mgbe ị na-emepụta njikọ, naanị SYN na ACK flags na-eji, ma mgbe ị na-agbanwe data, ngwugwu arịrịọ ikpeazụ ga-enwe ọkọlọtọ PSH. Ọ na-arụnye na-akpaghị aka ka ịzena nchekwa. Ị nwere ike iji ozi a mepụta nzacha: ọ ga-ekwe ka ngwugwu niile ma e wezụga ndị nwere ọkọlọtọ PSH. Ya mere, njikọ ahụ ga-eguzobe, mana onye ahịa agaghị enwe ike izipu data na ihe nkesa ahụ.
DARA
Maka DROP iwu a ga-adị ka nke a:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j DROP
Mepee onye ahịa wee lelee okporo ụzọ:
Mkpofu okporo ụzọ
[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
Anyị na-ahụ na e guzobere njikọ ahụ na onye ahịa enweghị ike izipu data na ihe nkesa ahụ.
J .R.
N'okwu a, omume ahụ ga-abụ otu: onye ahịa agaghị enwe ike izipu arịrịọ ahụ, mana ọ ga-anata ICMP 127.0.0.1 tcp ọdụ ụgbọ mmiri 12345 enweghị ike iru ma welie oge n'etiti ntinye akwụkwọ arịrịọ nke ukwuu. Iwu ahụ dị ka nke a:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j REJECT
Jụgharịa na tcp-tọgharịa
Iwu ahụ dị ka nke a:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j REJECT --reject-with tcp-reset
Anyị amaralarị nke ahụ mgbe eji --ajụ-na tcp-tọgharịa onye ahịa ahụ ga-enweta ngwugwu RST na nzaghachi, ya mere enwere ike ibu amụma omume: ịnweta ngwugwu RST mgbe njikọ njikọ ahụ pụtara na oghere na-atụghị anya na-emechi n'akụkụ nke ọzọ, nke pụtara na onye ahịa kwesịrị ịnata. Tọgharia njikọ site na ndị ọgbọ. Ka anyị na-agba ọsọ anyị script wee hụ na nke a. Ma nke a bụ ihe okporo ụzọ ga-adị ka:
Mkpofu okporo ụzọ
[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
Jụọ ya na icmp-host-enweghị ike iru ya
Echere m na ọ dịlarị onye ọ bụla anya ihe iwu ahụ ga-adị ka :) Omume nke onye ahịa na nke a ga-adịtụ iche na nke a na-eme ka ọ dị mfe REJECT: onye ahịa agaghị abawanye oge n'etiti mgbalị iji zipu ngwugwu ahụ.
[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
nkwubi
Ọ dịghị mkpa ide ihe njakịrị iji nwalee mmekọrịta nke ọrụ na onye ahịa ma ọ bụ ihe nkesa kwụgburu; mgbe ụfọdụ ọ na-ezuru iji ọkọlọtọ ọkọlọtọ dị na Linux.
Ngwa ndị a tụlere n'isiokwu ahụ nwere ikike karịa ka a kọwara, yabụ ị nwere ike wepụta ụfọdụ nhọrọ nke gị maka iji ha. Onwe m, enwere m oge zuru oke nke ihe m dere (n'ezie, ọbụlagodi obere). Ọ bụrụ na ị na-eji ihe ndị a ma ọ bụ ihe ndị yiri ya na nnwale na ụlọ ọrụ gị, biko dee otu esi eme ya. Ọ bụrụ na ọ bụghị, mgbe ahụ enwere m olileanya na ngwanrọ gị ga-aka mma ma ọ bụrụ na ị kpebie ịnwale ya na ọnọdụ nsogbu netwọk site na iji ụzọ ndị a tụrụ aro.
isi: www.habr.com