地址：http://www.thegeekstuff.com/2010/03/netstat-command-examples/

1.列出所有的端口

  netstat -a
  列出TCP协议的端口
  netstat -at
  UDP协议的端口
  netstat -au

2.列出处于监听状态的socket

  netstat -l
  列出监听的TCP端口
  netstat -lt
  列出监听的UDP端口
  netstat -lu
  列出监听的UNIX端口
  netstat -lx

3.列出协议的统计信息

  nestat -s
  比如： Ip:
    11150 total packets received
    1 with invalid addresses
    0 forwarded
    0 incoming packets discarded
    11149 incoming packets delivered
    11635 requests sent out
Icmp:
    0 ICMP messages received
    0 input ICMP message failed.
Tcp:
    582 active connections openings
    2 failed connection attempts