linux中netstat命令详解及常见用法

在Linux使用过程中,需要了解当前系统开放了哪些端口,并且要查看开放这些端口的具体进程和用户,可以通过netstat命令进行简单查询

1.netstat命令各个参数说明

-a   或–all                             显示所有连线中的Socket。
-A                                       <网络类型>或–<网络类型> 列出该网络类型连线中的相关地址。
-c   或–continuous               持续列出网络状态。
-C 或–cache                       显示路由器配置的快取信息。
-e  或–extend                     显示网络其他相关信息。
-F  或 –fib                          显示FIB。
-g  或–groups                     显示多重广播功能群组组员名单。
-h  或–help                        在线帮助。
-i   或–interfaces                 显示网络界面信息表单。
-l  或–listening                    显示监控中的服务器的Socket。
-M   或–masquerade           显示伪装的网络连线。
-n  或–numeric                   直接使用IP地址,而不通过域名服务器。
-N   或–netlink或–symbolic  显示网络硬件外围设备的符号连接名称。
-o  或–timers                      显示计时器。
-p   或–programs                显示正在使用Socket的程序识别码和程序名称。
-r  或–route                        显示 Routing Table。 
-s  或–statistice 显示网络工作信息统计表。
-t  或–tcp 显示TCP 传输协议的连线状况。
-u或–udp 显示UDP传输协议的连线状况。
-v或–verbose 显示指令执行过程。
-V 或–version 显示版本信息。
-w或–raw 显示RAW传输协议的连线状况。
-x或–unix 此参数的效果和指定”-A unix”参数相同。
–ip或–inet 此参数的效果和指定”-A inet”参数相同。

2.查看当前所有tcp端口使用情况

linux中netstat命令详解及常见用法_第1张图片

这里解释一下:

1、0.0.0.0代表本机上可用的任意地址。 比如0.0.0.0:135 表示本机上所有地址的135端口,这样多ip计算机就不用重复显示了。
2、TCP 0.0.0.0:80表示在所有的可用接口上监听TCP80端口 
3、0.0.0.0为默认路由,即要到达不再路由表里面的网段的包都走0.0.0.0这条规则

然后127.0.0.1就是表示你本机ip地址的意思了。

然后[::]:21这又是什么鬼?

这个表示ipv6的21号端口的意思。

还有UDP的外部链接怎么都是*:*呢?

*:*是网址的通配符,就是192.168.15.12,这个类型的整体描述

这里解释一下:

1、0.0.0.0代表本机上可用的任意地址。 比如0.0.0.0:135 表示本机上所有地址的135端口,这样多ip计算机就不用重复显示了。
2、TCP 0.0.0.0:80表示在所有的可用接口上监听TCP80端口 
3、0.0.0.0为默认路由,即要到达不再路由表里面的网段的包都走0.0.0.0这条规则

然后127.0.0.1就是表示你本机ip地址的意思了。

然后[::]:21这又是什么鬼?

这个表示ipv6的21号端口的意思。

还有UDP的外部链接怎么都是*:*呢?

*:*是网址的通配符,就是192.168.15.12,这个类型的整体描述

注意:127.0.0.1 和 0.0.0.0 是两种不同的网络地址。127.0.0.1 是一个环回地址,只能本地访问,用于本地测试和调试12。0.0.0.0 是一个通配地址,可以接受来自本地和外部网络的连接,用于在开发环境中监听所有可用的网络接口

3.tcp端口使用的状态解释

LISTEN:(Listening for a connection.)侦听来自远方的TCP端口的连接请求

SYN-SENT:(Active; sent SYN. Waiting for a matching connection request after having sent a connection request.)再发送连接请求后等待匹配的连接请求

SYN-RECEIVED:(Sent and received SYN. Waiting for a confirming connection request acknowledgment after having both received and sent connection requests.)再收到和发送一个连接请求后等待对方对连接请求的确认

ESTABLISHED:(Connection established.)代表一个打开的连接

FIN-WAIT-1:(Closed; sent FIN.)等待远程TCP连接中断请求,或先前的连接中断请求的确认

FIN-WAIT-2:(Closed; FIN is acknowledged; awaiting FIN.)从远程TCP等待连接中断请求

CLOSE-WAIT:(Received FIN; waiting to receive CLOSE.)等待从本地用户发来的连接中断请求

CLOSING:(Closed; exchanged FIN; waiting for FIN.)等待远程TCP对连接中断的确认

LAST-ACK:(Received FIN and CLOSE; waiting for FIN ACK.)等待原来的发向远程TCP的连接中断请求的确认

TIME-WAIT:(In 2 MSL (twice the maximum segment length) quiet wait after close. )等待足够的时间以确保远程TCP接收到连接中断请求的确认

CLOSED:(Connection is closed.)没有任何连接状态

UNKNOWN:套接字状态未知

4.netstat的10个基本用法

①:列出所有连接

[root@VM-12-14-centos test]# netstat -a

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:25672           0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:mysql           0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:5901            0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:sunrpc          0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:http            0.0.0.0:*               LISTEN     
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:65311 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:53118 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:64199 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.stati:954 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:25276 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:39902 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:51665 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:13772 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:12621 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:17978 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:63730 SYN_RECV   
tcp        0      0 0.0.0.0:epmd            0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:6001            0.0.0.0:*               LISTEN     
tcp        0      0 VM-12-14-centos:domain  0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:ssh             0.0.0.0:*               LISTEN     
tcp        0      0 VM-12-14-centos:ipp     0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:15672           0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:kerberos        0.0.0.0:*               LISTEN     
tcp        0      0 VM-12-14:x11-ssh-offset 0.0.0.0:*               LISTEN     
tcp        0      0 VM-12-14-centos:57884   VM-12-14-centos:epmd    TIME_WAIT  
tcp        0      0 VM-12-14-centos:52702   169.254.0.138:8186      ESTABLISHED
tcp        0      0 VM-12-14-centos:epmd    VM-12-14-centos:40859   ESTABLISHED
tcp        0      0 VM-12-14-centos:40859   VM-12-14-centos:epmd    ESTABLISHED
tcp        0     48 VM-12-14-centos:ssh     120.224.104.72:52646    ESTABLISHED

常见字段解释
proto 套接字使用的协议是什么
Recv-0 连接这个套接字的用户,还未拷贝的字节数
Send-0 远程主机还未确认的字节数
Local address套接字(一个连接情况)本地的地址和端口号317
Foreign Address 套接字的远程主机地址和口号
State套接字的运行情况

②:只列出TCP或UDP协议的连接

使用 -t 选项列出 TCP 协议的连接
[root@VM-12-14-centos test]# netstat -at

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:25672           0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:mysql           0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:5901            0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:sunrpc          0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:http            0.0.0.0:*               LISTEN     
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:24962 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:12954 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:21002 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:65432 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:39178 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:47736 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:49636 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    45.135.201.241:59717    SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:32799 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:14283 SYN_RECV   
tcp        0      0 VM-12-14-centos:http    103-148-72-71.sta:56900 SYN_RECV   

使用 -u 选项列出 UDP 协议的连接
[root@VM-12-14-centos test]# netstat -au

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
udp        0      0 0.0.0.0:884             0.0.0.0:*                          
udp        0      0 0.0.0.0:mdns            0.0.0.0:*                          
udp        0      0 VM-12-14-centos:domain  0.0.0.0:*                          
udp        0      0 0.0.0.0:bootps          0.0.0.0:*                          
udp        0      0 0.0.0.0:bootpc          0.0.0.0:*                          
udp        0      0 0.0.0.0:sunrpc          0.0.0.0:*                          
udp        0      0 VM-12-14-centos:ntp     0.0.0.0:*                          
udp        0      0 VM-12-14-centos:ntp     0.0.0.0:*                          
udp        0      0 0.0.0.0:45625           0.0.0.0:*                          
udp6       0      0 [::]:884                [::]:*                             
udp6       0      0 [::]:sunrpc             [::]:*                             
udp6       0      0 VM-12-14-centos:ntp     [::]:*                             
udp6       0      0 VM-12-14-centos:ntp     [::]:*                             

③:禁用反向域名解析,加快查询速度

默认情况下 netstat 会通过反向域名解析技术查找每个 IP 地址对应的主机名。这会降低查找速度。如果你觉得 IP 地址已经足够,而没有必要知道主机名,就使用 -n 选项禁用域名解析功能

[root@VM-12-14-centos test]# netstat -an

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:25672           0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:5901            0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN     
tcp        0      0 10.0.12.14:80           103.148.72.71:36631     SYN_RECV   
tcp        0      0 10.0.12.14:80           103.148.72.71:8279      SYN_RECV   
tcp        0      0 10.0.12.14:80           103.148.72.71:65432     SYN_RECV   
tcp        0      0 10.0.12.14:80           103.148.72.71:43150     SYN_RECV   
tcp        0      0 10.0.12.14:80           103.148.72.71:58653     SYN_RECV   
tcp        0      0 10.0.12.14:80           103.148.72.71:12405     SYN_RECV   
tcp        0      0 10.0.12.14:80           103.148.72.71:25388     SYN_RECV   
tcp        0      0 10.0.12.14:80           103.148.72.71:41411     SYN_RECV   
tcp        0      0 10.0.12.14:80           103.148.72.71:56328     SYN_RECV   
tcp        0      0 10.0.12.14:80           103.148.72.71:3576      SYN_RECV   
tcp        0      0 10.0.12.14:80           103.148.72.71:7845      SYN_RECV  

④:只列出监听中的连接

任何网络服务的后台进程都会打开一个端口,用于监听接入的请求。这些正在监听的套接字也和连接的套接字一样,也能被 netstat 列出来。使用 -l 选项列出正在监听的套接字

[root@VM-12-14-centos test]# netstat -tnl

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:25672           0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:5901            0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:4369            0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:6001            0.0.0.0:*               LISTEN     
tcp        0      0 192.168.122.1:53        0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN     
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:15672           0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:88              0.0.0.0:*               LISTEN     
tcp        0      0 127.0.0.1:6010          0.0.0.0:*               LISTEN     
tcp6       0      0 :::5672                 :::*                    LISTEN     
tcp6       0      0 :::3306                 :::*                    LISTEN     
tcp6       0      0 :::5901                 :::*                    LISTEN     
tcp6       0      0 :::111                  :::*                    LISTEN     
tcp6       0      0 :::4369                 :::*                    LISTEN     
tcp6       0      0 :::6001                 :::*                    LISTEN     
tcp6       0      0 :::22                   :::*                    LISTEN     
tcp6       0      0 ::1:631                 :::*                    LISTEN     
tcp6       0      0 ::1:6010                :::*                    LISTEN  

现在我们可以看到处于监听状态的 TCP 端口和连接。如果你查看所有监听端口,去掉 -t 选项。如果你只想查看 UDP 端口,使用 -u 选项,代替 -t 选项。

注意:不要使用 -a 选项,否则 netstat 会列出所有连接,而不仅仅是监听端口

⑤:获取进程名、进程号以及用户ID

查看端口和连接的信息时,能查看到它们对应的进程名和进程号对系统管理员来说是非常有帮助的。举个栗子,Apache 的 httpd 服务开启80端口,如果你要查看 http 服务是否已经启动,或者 http 服务是由 apache 还是 nginx 启动的,这时候你可以看看进程名

使用 -p 选项查看进程信息

[root@VM-12-14-centos test]# netstat -nlpt

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 0.0.0.0:25672           0.0.0.0:*               LISTEN      1110/beam.smp       
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN      21083/docker-proxy  
tcp        0      0 0.0.0.0:5901            0.0.0.0:*               LISTEN      1508/Xvnc           
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN      713/rpcbind         
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      1407/nginx: master  
tcp        0      0 0.0.0.0:4369            0.0.0.0:*               LISTEN      2136/epmd           
tcp        0      0 0.0.0.0:6001            0.0.0.0:*               LISTEN      1508/Xvnc           
tcp        0      0 192.168.122.1:53        0.0.0.0:*               LISTEN      1950/dnsmasq        
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1372/sshd           
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN      1119/cupsd          
tcp        0      0 0.0.0.0:15672           0.0.0.0:*               LISTEN      1110/beam.smp       
tcp        0      0 0.0.0.0:88              0.0.0.0:*               LISTEN      1407/nginx: master  
tcp        0      0 127.0.0.1:6010          0.0.0.0:*               LISTEN      3701/sshd: root@pts 
tcp6       0      0 :::5672                 :::*                    LISTEN      1110/beam.smp       
tcp6       0      0 :::3306                 :::*                    LISTEN      21088/docker-proxy  
tcp6       0      0 :::5901                 :::*                    LISTEN      1508/Xvnc           
tcp6       0      0 :::111                  :::*                    LISTEN      713/rpcbind         
tcp6       0      0 :::4369                 :::*                    LISTEN      2136/epmd           
tcp6       0      0 :::6001                 :::*                    LISTEN      1508/Xvnc           
tcp6       0      0 :::22                   :::*                    LISTEN      1372/sshd           
tcp6       0      0 ::1:631                 :::*                    LISTEN      1119/cupsd          
tcp6       0      0 ::1:6010                :::*                    LISTEN      3701/sshd: root@pts 

使用 -p 选项时,netstat 必须运行在 root 权限之下,不然它就不能得到运行在 root 权限下的进程名,而很多服务包括 http 和 ftp 都运行在 root 权限之下

相比进程名和进程号而言,查看进程的拥有者会更有用。使用 -ep 选项可以同时查看进程名和用户名

[root@VM-12-14-centos test]# netstat -ltpe

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       User       Inode      PID/Program name    
tcp        0      0 0.0.0.0:25672           0.0.0.0:*               LISTEN      rabbitmq   35092      1110/beam.smp       
tcp        0      0 0.0.0.0:mysql           0.0.0.0:*               LISTEN      root       138883     21083/docker-proxy  
tcp        0      0 0.0.0.0:5901            0.0.0.0:*               LISTEN      root       31801      1508/Xvnc           
tcp        0      0 0.0.0.0:sunrpc          0.0.0.0:*               LISTEN      root       19890      713/rpcbind         
tcp        0      0 0.0.0.0:http            0.0.0.0:*               LISTEN      root       31241      1407/nginx: master  
tcp        0      0 0.0.0.0:epmd            0.0.0.0:*               LISTEN      rabbitmq   34894      2136/epmd           
tcp        0      0 0.0.0.0:6001            0.0.0.0:*               LISTEN      root       31793      1508/Xvnc           
tcp        0      0 VM-12-14-centos:domain  0.0.0.0:*               LISTEN      root       32486      1950/dnsmasq        
tcp        0      0 0.0.0.0:ssh             0.0.0.0:*               LISTEN      root       30494      1372/sshd           
tcp        0      0 VM-12-14-centos:ipp     0.0.0.0:*               LISTEN      root       26582      1119/cupsd          
tcp        0      0 0.0.0.0:15672           0.0.0.0:*               LISTEN      rabbitmq   39837      1110/beam.smp       
tcp        0      0 0.0.0.0:kerberos        0.0.0.0:*               LISTEN      root       31242      1407/nginx: master  
tcp        0      0 VM-12-14:x11-ssh-offset 0.0.0.0:*               LISTEN      root       2148874    3701/sshd: root@pts 
tcp6       0      0 [::]:amqp               [::]:*                  LISTEN      rabbitmq   38151      1110/beam.smp       
tcp6       0      0 [::]:mysql              [::]:*                  LISTEN      root       137704     21088/docker-proxy  
tcp6       0      0 [::]:5901               [::]:*                  LISTEN      root       31802      1508/Xvnc           
tcp6       0      0 [::]:sunrpc             [::]:*                  LISTEN      root       19893      713/rpcbind         
tcp6       0      0 [::]:epmd               [::]:*                  LISTEN      rabbitmq   34895      2136/epmd           
tcp6       0      0 [::]:6001               [::]:*                  LISTEN      root       31792      1508/Xvnc           
tcp6       0      0 [::]:ssh                [::]:*                  LISTEN      root       30579      1372/sshd           
tcp6       0      0 VM-12-14-centos:ipp     [::]:*                  LISTEN      root       26581      1119/cupsd          
tcp6       0      0 VM-12-14:x11-ssh-offset [::]:*                  LISTEN      root       2148873    3701/sshd: root@pts

上面列出 TCP 协议下的监听套接字,同时显示进程信息和一些额外信息。

这些额外的信息包括用户名和进程的索引节点号。这个命令对网管来说很有用。

注意 - 假如你将 -n 和 -e 选项一起使用,User 列的属性就是用户的 ID 号,而不是用户名

⑥:打印统计数据

netstat 可以打印出网络统计数据,包括某个协议下的收发包数量

[root@VM-12-14-centos test]# netstat -s

Ip:
    619929 total packets received
    1265 forwarded
    0 incoming packets discarded
    618658 incoming packets delivered
    762156 requests sent out
    40 dropped because of missing route
Icmp:
    42560 ICMP messages received
    29 input ICMP message failed.
    ICMP input histogram:
        destination unreachable: 34
        redirects: 8
        echo requests: 42518
    42615 ICMP messages sent
    0 ICMP messages failed
    ICMP output histogram:
        destination unreachable: 97
        echo replies: 42518
IcmpMsg:
        InType3: 34
        InType5: 8
        InType8: 42518
        OutType0: 42518
        OutType3: 97
Tcp:
    33204 active connections openings
    35706 passive connection openings
    5010 failed connection attempts
    963 connection resets received
    7 connections established
    557820 segments received
    689021 segments send out
    175537 segments retransmited
    19 bad segments received.
    59219 resets sent
    InCsumErrors: 12
Udp:
    17262 packets received
    102 packets to unknown port received.
    0 packet receive errors
    17381 packets sent
    0 receive buffer errors
    0 send buffer errors
UdpLite:
TcpExt:
    7565 invalid SYN cookies received
    5010 resets received for embryonic SYN_RECV sockets
    11 packets pruned from receive queue because of socket buffer overrun
    1 ICMP packets dropped because they were out-of-window
    2997 TCP sockets finished time wait in fast timer
    3 packets rejects in established connections because of timestamp
    15638 delayed acks sent
    4 delayed acks further delayed because of locked socket
    Quick ack mode was activated 658 times
    4 SYNs to LISTEN sockets dropped
    1224 packets directly queued to recvmsg prequeue.
    235 bytes directly received in process context from prequeue
    58146 packet headers predicted
    184612 acknowledgments not containing data payload received
    34227 predicted acknowledgments
    30 times recovered from packet loss by selective acknowledgements
    1 congestion windows recovered without slow start by DSACK
    127 congestion windows recovered without slow start after partial ack
    1 timeouts after reno fast retransmit
    12 timeouts after SACK recovery
    1 timeouts in loss state
    24 fast retransmits
    6 forward retransmits
    32 retransmits in slow start
    197634 other TCP timeouts
    TCPLossProbes: 3946
    TCPLossProbeRecovery: 509
    5 SACK retransmits failed
    632 DSACKs sent for old packets
    3 DSACKs sent for out of order packets
    1530 DSACKs received
    2523 connections reset due to unexpected data
    861 connections reset due to early user close
    51 connections aborted due to timeout
    TCPDSACKIgnoredNoUndo: 419
    TCPSpuriousRTOs: 2
    TCPSackShiftFallback: 169
    TCPRcvCoalesce: 38207
    TCPOFOQueue: 2251
    TCPOFOMerge: 3
    TCPChallengeACK: 123
    TCPSYNChallenge: 7
    TCPWantZeroWindowAdv: 1
    TCPSynRetrans: 164576
    TCPOrigDataSent: 232528
    TCPACKSkippedSynRecv: 10
    TCPACKSkippedSeq: 2
    TCPACKSkippedChallenge: 1
IpExt:
    InNoRoutes: 6
    InMcastPkts: 1111
    OutMcastPkts: 1123
    InOctets: 105748257
    OutOctets: 99010928
    InMcastOctets: 55945
    OutMcastOctets: 60254
    InNoECTPkts: 654410
    InECT1Pkts: 2870
    InECT0Pkts: 1

⑦:显示内核路由信息

使用 -r 选项打印内核路由信息。打印出来的信息与 route 命令输出的信息一样。我们也可以使用 -n 选项禁止域名解析

[root@VM-12-14-centos test]# netstat -rn

Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         10.0.12.1       0.0.0.0         UG        0 0          0 eth0
10.0.0.0        10.0.12.1       255.255.255.0   UG        0 0          0 eth0
10.0.0.10       10.0.13.1       255.255.255.255 UGH       0 0          0 eth0
10.0.2.0        0.0.0.0         255.255.255.0   U         0 0          0 eth0
10.0.12.0       0.0.0.0         255.255.252.0   U         0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0
172.17.0.0      0.0.0.0         255.255.0.0     U         0 0          0 docker0
172.18.0.0      0.0.0.0         255.255.0.0     U         0 0          0 br-a0d112e232a1
172.19.0.0      0.0.0.0         255.255.0.0     U         0 0          0 br-23353f657e8b
192.168.122.0   0.0.0.0         255.255.255.0   U         0 0          0 virbr0
224.0.0.0       -               240.0.0.0       !         - -          - -
224.0.0.0       0.0.0.0         240.0.0.0       U         0 0          0 eth0

⑧:打印网络接口

netstat 也能打印网络接口信息,-i 选项就是为这个功能而生

[root@VM-12-14-centos test]# netstat -i 

Kernel Interface table
Iface             MTU    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg
br-23353f657e8b  1500      711      0      0 0           706      0      0      0 BMU
br-a0d112e232a1  1500      711      0      0 0           706      0      0      0 BMU
docker0          1500      711      0      0 0           698      0      0      0 BMRU
eth0             1500   646680      0      0 0        751767      0      0      0 BMRU
eth0:1           1500      - no statistics available -                        BMRU
eth0:2           1500      - no statistics available -                        BMRU
lo              65536    21313      0      0 0         21313      0      0      0 LRU
vethfb859b6      1500      711      0      0 0           706      0      0      0 BMRU
virbr0           1500        0      0      0 0             0      0      0      0 BMU

字段解释:
Iface网络设备的名字
MTU 最大的传输单元,单位是字节
RX-0K/TX-0K 正确接收了多少数据包,发送了多少数据包
RX-ERR/TX-ERR 接收、发送数据包的时候,丢弃了多少数据包
RX-0VR/TX-0VR 由于错误遗失了多少的数据包

FLg标记
    L是回环地址的含义
    R:这个网络接口正在运行中,U:接口正在处于活动的状态
    B:设置了广播地址
    M:接收所有的数据包
    O:表示在该接口上禁止arp
    P:端对端的连接
查看TX-ERR RX-ERR最好是0,否则表示网络情况不健康,有丢包的现象

上面输出的信息比较原始。我们将 -e 选项和 -i 选项搭配使用,可以输出用户友好的信息

[root@VM-12-14-centos test]# netstat -ie

Kernel Interface table
br-23353f657e8b: flags=4099  mtu 1500
        inet 172.19.0.1  netmask 255.255.0.0  broadcast 172.19.255.255
        ether 02:42:69:59:5d:f8  txqueuelen 0  (Ethernet)
        RX packets 711  bytes 63222 (61.7 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 706  bytes 57772 (56.4 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

br-a0d112e232a1: flags=4099  mtu 1500
        inet 172.18.0.1  netmask 255.255.0.0  broadcast 172.18.255.255
        ether 02:42:65:59:4e:7a  txqueuelen 0  (Ethernet)
        RX packets 711  bytes 63222 (61.7 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 706  bytes 57772 (56.4 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

docker0: flags=4163  mtu 1500
        inet 172.17.0.1  netmask 255.255.0.0  broadcast 172.17.255.255
        inet6 fe80::42:4aff:fe93:976b  prefixlen 64  scopeid 0x20
        ether 02:42:4a:93:97:6b  txqueuelen 0  (Ethernet)
        RX packets 711  bytes 53268 (52.0 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 698  bytes 57116 (55.7 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth0: flags=4163  mtu 1500
        inet 10.0.12.14  netmask 255.255.252.0  broadcast 10.0.15.255
        inet6 fe80::5054:ff:fe39:b685  prefixlen 64  scopeid 0x20
        ether 52:54:00:39:b6:85  txqueuelen 1000  (Ethernet)
        RX packets 647172  bytes 115417012 (110.0 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 752274  bytes 108765481 (103.7 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth0:1: flags=4163  mtu 1500
        inet 10.0.2.18  netmask 255.255.255.0  broadcast 10.0.2.255
        ether 52:54:00:39:b6:85  txqueuelen 1000  (Ethernet)

eth0:2: flags=4163  mtu 1500
        inet 10.0.2.17  netmask 255.255.255.0  broadcast 10.0.2.255
        ether 52:54:00:39:b6:85  txqueuelen 1000  (Ethernet)

lo: flags=73  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 21333  bytes 1221206 (1.1 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 21333  bytes 1221206 (1.1 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

vethfb859b6: flags=4163  mtu 1500
        inet6 fe80::fcbf:a0ff:fe31:9587  prefixlen 64  scopeid 0x20
        ether fe:bf:a0:31:95:87  txqueuelen 0  (Ethernet)
        RX packets 711  bytes 63222 (61.7 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 706  bytes 57772 (56.4 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

virbr0: flags=4099  mtu 1500
        inet 192.168.122.1  netmask 255.255.255.0  broadcast 192.168.122.255
        ether 52:54:00:fa:a2:70  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        
上面的输出信息与 ifconfig 输出的信息一样       

⑨:netstat持续输出

我们可以使用 netstat 的 -c 选项持续输出信息

[root@VM-12-14-centos test]# netstat -c

⑩:显示多播信息

选项 -g 会输出 IPv4 和 IPv6 的多播组信息

[root@VM-12-14-centos test]# netstat -g

IPv6/IPv4 Group Memberships
Interface       RefCnt Group
--------------- ------ ---------------------
lo              1      all-systems.mcast.net
eth0            1      mdns.mcast.net
eth0            1      all-systems.mcast.net
virbr0          1      mdns.mcast.net
virbr0          1      all-systems.mcast.net
br-23353f657e8b 1      mdns.mcast.net
br-23353f657e8b 1      all-systems.mcast.net
br-a0d112e232a1 1      mdns.mcast.net
br-a0d112e232a1 1      all-systems.mcast.net
docker0         1      mdns.mcast.net
docker0         1      all-systems.mcast.net
vethfb859b6     1      all-systems.mcast.net
lo              1      ff02::1
lo              1      ff01::1
eth0            1      ff02::1:ff39:b685
eth0            1      ff02::1
eth0            1      ff01::1
virbr0          1      ff02::1
virbr0          1      ff01::1
virbr0-nic      1      ff02::1
virbr0-nic      1      ff01::1
br-23353f657e8b 1      ff02::1
br-23353f657e8b 1      ff01::1
br-a0d112e232a1 1      ff02::1
br-a0d112e232a1 1      ff01::1
docker0         1      ff02::1:ff93:976b
docker0         1      ff02::1
docker0         1      ff01::1
vethfb859b6     1      ff02::1:ff31:9587
vethfb859b6     1      ff02::1
vethfb859b6     1      ff01::1

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