以前netstat这个命令经常用，但是用的真是稀里糊涂的，写下加深一下印象
常见参数
-a 显示多有的选项，默认是不监听listen的
-t tcp
-u udp
-p 显示建立相关连接的程序名称
-n 把端口，username，域名 都显示成数组，不会根据ip在定位域名，所以速度会相对快点
-l 仅显示监听
-s 显示每个协议的相关统计
如果是root启用的，普通用户是无法看到程序名称的
[jimmy@xxx ~]$ netstat -altp (No info could be read for "-p": geteuid()=1000 but you should be root.) Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:ssh 0.0.0.0:* LISTEN - tcp 0 0 iZ258ugv6ktZ:ssh 220.181.165.11:56273 ESTABLISHED - tcp 0 0 iZ258ugv6ktZ:ssh 220.181.165.10:46172 ESTABLISHED - tcp 0 544 iZ258ugv6ktZ:ssh 220.181.165.7:51149 ESTABLISHED - tcp 0 0 iZ258ugv6ktZ:57580 110.75.102.62:http ESTABLISHED -
[root@aliyun ~/]netstat -atlp Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:ssh 0.0.0.0:* LISTEN 867/sshd tcp 0 384 iZ258ugv6ktZ:ssh 220.181.165.11:56273 ESTABLISHED 32210/sshd: root@pt tcp 0 0 iZ258ugv6ktZ:ssh 220.181.165.10:46172 ESTABLISHED 32039/sshd: root@pt tcp 0 0 iZ258ugv6ktZ:ssh 220.181.165.7:51149 ESTABLISHED 32120/sshd: root@pt tcp 0 0 iZ258ugv6ktZ:57580 110.75.102.62:http ESTABLISHED 11910/AliYunDun
加 -n
[root@aliyun ~/]netstat -atlpn Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 867/sshd tcp 0 384 123.56.156.119:22 220.181.165.11:56273 ESTABLISHED 32210/sshd: root@pt tcp 0 0 123.56.156.119:22 220.181.165.10:46172 ESTABLISHED 32039/sshd: root@pt tcp 0 0 123.56.156.119:22 220.181.165.7:51149 ESTABLISHED 32120/sshd: root@pt tcp 0 0 123.56.156.119:57580 110.75.102.62:80 ESTABLISHED 11910/AliYunDun
watch -n 1 -d netstat -ant
-n 周期（s）
-d 高亮显示变动