代码如果有偏颇,请以
https://help.aliyun.com/knowledge_detail/40564.htm 为准
如果源服务器访问目标服务器出现异常,而且参阅文档
ping 丢包或不通时链路测试说明 和
能 ping 通但端口不通时端口可用性探测说明 排查分析处理后,还是未能解决问题,则需要通过抓包获取最原始的交互数据做进一步排查分析。本文先介绍了常用的抓包工具,然后对抓包的操作步骤进行了简要说明。本文不涉及抓包数据的分析处理说明。
常用抓包工具介绍
tcpdump [ -AbdDefhHIJKlLnNOpqStuUvxX# ] [ -B buffer_size ]
[ -c count ]
[ -C file_size ] [ -G rotate_seconds ] [ -F file ]
[ -i interface ] [ -j tstamp_type ] [ -m module ] [ -M secret ]
[ --number ] [ -Q in|out|inout ]
[ -r file ] [ -V file ] [ -s snaplen ] [ -T type ] [ -w file ]
[ -W filecount ]
[ -E spi@ipaddr algo:secret,... ]
[ -y datalinktype ] [ -z postrotate-command ] [ -Z user ]
[ --time-stamp-precision=tstamp_precision ]
[ --immediate-mode ] [ --version ]
[ expression ]
tcpdump -s 0 -i eth0 port 22
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
20:24:59.414951 IP 172.16.2.226.ssh > 42.120.74.107.43414: Flags [P.], seq 442372:442536, ack 53, win 141, length 164
20:24:59.415002 IP 172.16.2.226.ssh > 42.120.74.107.43414: Flags [P.], seq 442536:442700, ack 53, win 141, length 164
20:24:59.415052 IP 172.16.2.226.ssh > 42.120.74.107.43414: Flags [P.], seq 442700:442864, ack 53, win 141, length 164
20:24:59.415103 IP 172.16.2.226.ssh > 42.120.74.107.43414: Flags [P.], seq 442864:443028, ack 53, win 141, length 164
tcpdump -s 0 -i eth1 -vvv port 22
tcpdump: listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes
20:24:20.991006 IP (tos 0x10, ttl 64, id 22747, offset 0, flags [DF], proto TCP (6), length 316)
172.16.2.226.ssh > 42.120.74.107.43414: Flags [P.], cksum 0x2504 (incorrect -> 0x270d), seq 133624:133900, ack 1, win 141, length 276
20:24:20.991033 IP (tos 0x0, ttl 53, id 2348, offset 0, flags [DF], proto TCP (6), length 92)
42.120.74.107.43414 > 172.16.2.226.ssh: Flags [P.], cksum 0x4759 (correct), seq 1:53, ack 129036, win 15472, length 52
20:24:20.991130 IP (tos 0x10, ttl 64, id 22748, offset 0, flags [DF], proto TCP (6), length 540)
172.16.2.226.ssh > 42.120.74.107.43414: Flags [P.], cksum 0x25e4 (incorrect -> 0x5e78), seq 133900:134400, ack 53, win 141, length 500
20:24:20.991162 IP (tos 0x0, ttl 53, id 2349, offset 0, flags [DF], proto TCP (6), length 40)
42.120.74.107.43414 > 172.16.2.226.ssh: Flags [.], cksum 0xf39e (correct), seq 53, ack 129812, win 15278, length 0
tcpdump -s 0 -i eth1 -vvv dst 223.5.5.5 and icmp
tcpdump: listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes
20:26:00.368958 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
172.16.2.226 > public1.alidns.com: ICMP echo request, id 55097, seq 341, length 64
20:26:01.369996 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
172.16.2.226 > public1.alidns.com: ICMP echo request, id 55097, seq 342, length 64
20:26:02.371058 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
172.16.2.226 > public1.alidns.com: ICMP echo request, id 55097, seq 343, length 64
20:26:03.372181 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 84)
172.16.2.226 > public1.alidns.com: ICMP echo request, id 55097, seq 344, length 64
tcpdump -i any -s 0 -w test.cap
tcpdump: listening on any, link-type LINUX_SLL (Linux cooked), capture size 65535 bytes
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