后台开发中netstat命令使用方法

麦辣鸡腿堡 2023-10-08 573

描述

后台开发，netstat命令总是绕不过，不仅工作中经常用过，面试也是考的多。netstat命令，对应的选项比较多，功能比较强大。netstat 常用来查看，后台服务进程的相关状态。

netstat 可以用来打印网络连接、路由表、连接的数据统计。下面我们来学习一下。

打印所有连接

使用 -a，列出所有连接。

[root@VM-16-9-centos ~]# netstat -a
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:ssh             0.0.0.0:*               LISTEN     
tcp        0      0 VM-16-9-centos:49326    169.254.0.55:lsi-bobcat ESTABLISHED
tcp        0     52 VM-16-9-centos:ssh      119.137.1.7:20029       ESTABLISHED
tcp        0      0 VM-16-9-centos:ssh      113.110.224.255:63626   ESTABLISHED
tcp6       0      0 [::]:mysql              [::]:*                  LISTEN     
udp        0      0 0.0.0.0:bootpc          0.0.0.0:*                          
udp        0      0 VM-16-9-centos:ntp      0.0.0.0:*                          
udp        0      0 VM-16-9-centos:ntp      0.0.0.0:*                          
udp        0      0 0.0.0.0:38064           0.0.0.0:*                          
udp6       0      0 VM-16-9-centos:ntp      [::]:*                             
udp6       0      0 VM-16-9-centos:ntp      [::]:*

打印 TCP 或 UDP 连接

使用 -t 选项列出 TCP 协议的连接。

[root@VM-16-9-centos ~]# netstat -t
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 VM-16-9-centos:49326    169.254.0.55:lsi-bobcat ESTABLISHED
tcp        0     52 VM-16-9-centos:ssh      119.137.1.7:20029       ESTABLISHED
tcp        0      0 VM-16-9-centos:ssh      113.110.224.255:63626   ESTABLISHED
tcp        0      0 VM-16-9-centos:ssh      vps-d395feee.vps.:39128 ESTABLISHED

使用 -u 选项列出 UDP 协议的连接。

[root@VM-16-9-centos ~]# netstat -u
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State

禁用反向域名解析

使用 -n 选项禁用域名解析功能，这样可以加快查找速度。

[root@VM-16-9-centos ~]# netstat -n
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 172.17.16.9:49326       169.254.0.55:5574       ESTABLISHED
tcp        0     52 172.17.16.9:22          119.137.1.7:20029       ESTABLISHED
tcp        0      0 172.17.16.9:22          113.110.224.255:63626   ESTABLISHED
tcp        0      0 172.17.16.9:52236       169.254.0.4:80          TIME_WAIT

显示对应的程序识别码和程序名称

使用 -p 选项列出正在监听的套接字。

[root@VM-16-9-centos ~]# netstat -p
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 VM-16-9-centos:49326    169.254.0.55:lsi-bobcat ESTABLISHED 1400/YDService      
tcp        0     52 VM-16-9-centos:ssh      119.137.1.7:20029       ESTABLISHED 22131/sshd: root@pt 
tcp        0      0 VM-16-9-centos:ssh      host-188-14-121-2:55529 TIME_WAIT   -                   
tcp        0      0 VM-16-9-centos:ssh      113.110.224.255:63626   ESTABLISHED 32201/sshd: root@pt

打印监听中的连接

使用 -l 选项列出正在监听的套接字。

[root@VM-16-9-centos ~]# netstat -l
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:ssh             0.0.0.0:*               LISTEN     
tcp6       0      0 [::]:mysql              [::]:*                  LISTEN     
udp        0      0 0.0.0.0:bootpc          0.0.0.0:*

打印连接进程信息

使用 -p 选项查看进程信息。

[root@VM-16-9-centos ~]# netstat -p
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 VM-16-9-centos:49326    169.254.0.55:lsi-bobcat ESTABLISHED 1400/YDService      
tcp        0      0 VM-16-9-centos:48680    169.254.0.55:webcache   TIME_WAIT   -                   
tcp        0     52 VM-16-9-centos:ssh      119.137.1.7:20029       ESTABLISHED 22131/sshd: root@pt 
tcp        0      0 VM-16-9-centos:ssh      113.110.224.255:63626   ESTABLISHED 32201/sshd: root@pt 
tcp        0      0 VM-16-9-centos:ssh      host-188-14-121-2:56025 ESTABLISHED 10384/sshd: unknown

打印网络工作信息统计表

使用 -s 选项查看进程信息(只展示部分结果)。

[root@VM-16-9-centos ~]# netstat -s
Ip:
    7502855 total packets received
    0 forwarded
    0 incoming packets discarded
    7502837 incoming packets delivered
    7624338 requests sent out
    40 dropped because of missing route
Icmp:
    938052 ICMP messages received
    147 input ICMP message failed.
    ICMP input histogram:
        destination unreachable: 411
        timeout in transit: 8
        redirects: 2
        echo requests: 937623
        echo replies: 7
        timestamp request: 1
    946258 ICMP messages sent
    0 ICMP messages failed
    ICMP output histogram:
        destination unreachable: 8634
        echo replies: 937623
        timestamp replies: 1

打印网络接口

使用 -i 选项查看进程信息。

[root@VM-16-9-centos ~]# netstat -i
Kernel Interface table
Iface             MTU    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0             1500  7825094      0      0 0       7712988      0      0      0 BMRU
lo              65536    10230      0      0 0         10230      0      0      0 LRU

持续输出信息

使用 -c 选项查看进程信息。

[root@VM-16-9-centos ~]# netstat -c
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 VM-16-9-centos:49326    169.254.0.55:lsi-bobcat ESTABLISHED
tcp        0     52 VM-16-9-centos:ssh      119.137.1.7:20029       ESTABLISHED
tcp        0      0 VM-16-9-centos:ssh      vps-d395feee.vps.:39442 ESTABLISHED
tcp        0      0 VM-16-9-centos:ssh      113.110.224.255:63626   ESTABLISHED
tcp        0      0 VM-16-9-centos:52660    169.254.0.4:http        TIME_WAIT  
tcp        0      0 VM-16-9-centos:ssh      b3d278e1.virtua.c:35113 TIME_WAIT  
tcp        0      0 VM-16-9-centos:ssh      58.230.147.230:56693    TIME_WAIT  
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags       Type       State         I-Node   Path
unix  3      [ ]         DGRAM                    7444     /run/systemd/notify

根据进程pid查端口

利用 grep 命令，通过进程 pid 查出监听端口。

[root@VM-16-9-centos test]# netstat -nap|grep 12178
tcp6       0      0 :::8888                 :::*                    LISTEN      12178/gin

根据端口查进程

利用 grep 命令，通过监听端口查出进程 pid 。

[root@VM-16-9-centos test]# netstat -nap|grep 8888
tcp6       0      0 :::8888                 :::*                    LISTEN      12178/gin

统计网络socket状态

借助 awk 命令，统计socket状态对应的个数。

[test]# netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}' 
ESTABLISHED 5
TIME_WAIT 2

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