1. netstat命令简介
netstat 命令用于显示各种网络相关信息，如网络连接，路由表，接口状态 (interface statistics)，masquerade 连接，多播成员 (multicast memberships) 等等。
netstat命令简介
2. 查看netstat 所有状态
[root@zcwyou ~]# netstat -a
active internet connections (servers and established)
proto recv-q send-q local address foreign address state
tcp 0 0 my_public_ip:9016 0.0.0.0:* listen
tcp 0 0 my_public_ip:9017 0.0.0.0:* listen
tcp 0 0 localhost:smtp 0.0.0.0:* listen
tcp 0 0 my_public_ip:9018 0.0.0.0:* listen
tcp 0 0 my_public_ip:pptp 0.0.0.0:* listen
tcp 0 0 my_public_ip:9019 0.0.0.0:* listen
3. 查看所有tcp连接
[root@zcwyou ~]# netstat -at
active internet connections (servers and established)
proto recv-q send-q local address foreign address state
tcp 0 0 my_public_ip:9016 0.0.0.0:* listen
tcp 0 0 my_public_ip:9017 0.0.0.0:* listen
tcp 0 0 localhost:smtp 0.0.0.0:* listen
tcp 0 0 my_public_ip:9018 0.0.0.0:* listen
tcp 0 0 my_public_ip:pptp 0.0.0.0:* listen
tcp 0 0 my_public_ip:9019 0.0.0.0:* listen
tcp 0 0 my_public_ip:tambora 0.0.0.0:* listen
tcp 0 0 my_public:etlservicemgr 0.0.0.0:* listen
tcp 0 0 my_public_ip:dynamid 0.0.0.0:* listen
tcp 0 0 my_public_ip:9003 0.0.0.0:* listen
4. 禁用反向域名解析，加快查询速度
[root@zcwyou ~]# netstat -ant
tcp 0 0 113.105.164.151:42342 202.46.36.30:9001 close_wait
tcp 0 0 113.105.164.151:49472 202.46.36.30:9001 established
tcp 0 0 113.105.164.151:43470 202.46.36.30:9001 close_wait
tcp 0 0 113.105.164.151:43576 202.46.36.30:9001 close_wait
tcp 0 0 113.105.164.151:9001 120.84.140.61:6290 fin_wait2
tcp 0 0 113.105.164.151:9015 183.14.29.69:6809 fin_wait2
tcp 0 0 113.105.164.151:35424 202.46.36.30:9002 close_wait
tcp 0 0 113.105.164.151:38074 202.46.36.30:9001 close_wait
tcp 0 0 113.105.164.151:9001 118.112.75.246:2710 fin_wait2
tcp 0 0 113.105.164.151:45124 202.46.36.30:9001 close_wait
tcp 0 0 113.105.164.151:37202 202.46.36.30:9001 close_wait
tcp 0 0 113.105.164.151:52640 202.46.36.30:9001 close_wait
5. 持续刷新信息
我们可以使用 netstat 的 -c 选项持续输出信息。
[root@zcwyou ~]# netstat -ct
6. 常见用法
6.1 查看所有tcp监听端口
[root@zcwyou ~]# netstat -lntp
linux查看所有tcp监听端口
6.2 查看所有的tcp连接情况
[root@zcwyou ~]# netstat -antp
6.3 查看所有udp连接情况
[root@zcwyou ~]# netstat -anp |sed -n '2p;/^udp/p'
6.4 查看所有已经建立的tcp连接
[root@zcwyou ~]# netstat -antp |sed -n '2p;/established/p'
linux查看所有已经建立的tcp连接
6.5 查看系统当前tcp连接数:
[root@zcwyou ~]# netstat -antp |sed -n '2p;/established/p' |wc -l
6.6 查看tcp半开连接,正常情况下,应该看不到有数据
[root@zcwyou ~]# netstat -nap | grep syn_recv
6.7 查看tcp半开连接数,正常情况下应该为0
[root@zcwyou ~]# netstat -nap | grep syn_recv |wc -l
6.8 查看网络统计信息
[root@zcwyou ~]# netstat -s
