linux netstat 命令简介

        -r, --route              显示路由表
        -i, --interfaces         显示接口信息表-s, --statistics         显示网络协议汇总信息
        -n, --numeric            不解析域名-p, --programs           为端口显示pid或者软件名称
        -o, --timers             显示计时器
        -c, --continuous         连续显示
        -l, --listening          显示正在监听的服务端口
        -a, --all                显示所有端口(默认只显示: connected 的端口)

#查看路由器表
[root@localhost ~]# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         10.10.0.1       0.0.0.0         UG        0 0          0 ens192
10.10.0.0       0.0.0.0         255.255.0.0     U         0 0          0 ens192
172.31.0.0      0.0.0.0         255.255.0.0     U         0 0          0 docker0

#查看正在监听的tcp端口，并显示对应的监听程序
[root@localhost ~]# netstat -ntpl 
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      15614/nginx: master 
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      6596/sshd           
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      6245/master         
tcp6       0      0 :::22                   :::*                    LISTEN      6596/sshd           
tcp6       0      0 ::1:25                  :::*                    LISTEN      6245/master         

#查看正在监听的udp端口，并显示对应的监听程序
[root@localhost ~]# netstat -nupl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
udp        0      0 127.0.0.1:323           0.0.0.0:*                           5711/chronyd        
udp6       0      0 ::1:323                 :::*                                5711/chronyd        

#显示所有tcp连接及监听端口
[root@localhost ~]# netstat -ant
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN     
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN     
tcp        0     96 10.10.0.110:22          172.17.1.128:56848      ESTABLISHED
tcp        0      0 10.10.0.110:22          172.17.1.128:62703      ESTABLISHED
tcp6       0      0 :::22                   :::*                    LISTEN     
tcp6       0      0 ::1:25                  :::*                    LISTEN     

#显示所有udp连接及监听端口及连接的程序
[root@localhost ~]# netstat -anup
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
udp        0      0 10.10.0.110:32932       114.114.114.114:53      ESTABLISHED 18481/nginx: worker 
udp        0      0 127.0.0.1:323           0.0.0.0:*                           5711/chronyd        
udp6       0      0 ::1:323                 :::*                                5711/chronyd