抓端口8080的包
tcpdump tcp port 8080 -n
tcpdump tcp port 8080 -w /tmp/xxxx.cap

抓119.29.121.116的80端口的包
tcpdump tcp port 8080 and host 10.104.102.228 -n
tcpdump tcp port 8080 and host 10.104.102.228 -w /tmp/xxxx.cap
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tcpdump 的抓包保存到文件的命令参数是-w xxx.cap

抓eth0的包

tcpdump -i eth0 -w /tmp/xxx.cap

抓端口8080的包

tcpdump tcp port 8080 -w /tmp/xxxx.cap

抓 119.29.121.116的包

tcpdump -i eth0 host 119.29.121.116 -w /tmp/xxx.cap

抓119.29.121.116的80端口的包

tcpdump -i eth0 host 119.29.121.116 and port 80 -w /tmp/xxx.cap

抓119.29.121.116的icmp的包

tcpdump -i eth0 host 119.29.121.116 and icmp -w /tmp/xxx.cap

抓119.29.121.116的80端口和110和25以外的其他端口的包

tcpdump -i eth0 host 119.29.121.116 and ! port 80 and ! port 25 and ! port 110 -w /tmp/xxx.cap

抓vlan 1的包

tcpdump -i eth0 port 80 and vlan 1 -w /tmp/xxx.cap

抓pppoe的密码

tcpdump -i eth0 pppoes -w /tmp/xxx.cap

以100m大小分割保存文件， 超过100m另开一个文件 -C 100m

抓10000个包后退出 -c 10000

后台抓包， 控制台退出也不会影响：

nohup tcpdump -i eth0 port 110 -w /tmp/xxx.cap &

抓下来的文件可以直接用ethereal 或者wireshark打开。