[root@test proc]# netstat -an
[root@test proc]# /usr/sbin/lsof -i |grep 21
proftpd 1408 root 0u IPv4 10850 1471 root 0u IPv4 21162 192.168.0.1:3631 (ESTABLISHED)
proftpd 1471 root 1u IPv4 21162 ;192.168.0.1:3631 (ESTABLISHED)
netstat -lp 查看端口使用
netstat -nap | grep 21 看看什么程序运行在21端口
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