【Linux 运维】查看网络连接状态信息之netstat和ss命令详解

一、netstat 常用命令 详解

通过man netstat可以查看netstat的帮助信息：

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，无效连接，组播成员等等。
netstat命令是net-tools软件包中的一员

[root@web129 ~]# netstat 选项

选项：

    -a:　　列出系统中所有网络连接，包括已经连接的网络服务、监听的网络服务和Socket套接字

    -t：　　列出TCP数据
    -u：　　列出UDP数据

    -l：　　列出正在监听的网络服务（不包含已经连接的网路服务）

    -n：　　用端口显示服务，而不用服务名

    -p：　　列出该服务的进程ID(PID)

示例一：netstat -tlunp

[root@web129 ~]# netstat -tlunp

Active Internet connections (only servers)

Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name

tcp               0.0.0.0:              0.0.0.0:*               LISTEN      /sshd

tcp               127.0.0.1:            0.0.0.0:*               LISTEN      /master

tcp6              :::                   :::*                    LISTEN      /httpd

tcp6              :::                   :::*                    LISTEN      /sshd

tcp6              :::                  :::*                    LISTEN      /master

udp               127.0.0.1:           0.0.0.0:*                           /chronyd

udp6              :::                 :::*                                /chronyd

[root@web129 ~]#

实例二:使用netstat -an

[root@web129 ~]# netstat -an

Active Internet connections (servers and established)

Proto Recv-Q Send-Q Local Address           Foreign Address         State

tcp               0.0.0.0:              0.0.0.0:*               LISTEN

tcp               127.0.0.1:            0.0.0.0:*               LISTEN

tcp               192.168.19.129:       192.168.19.1:       ESTABLISHED

tcp               192.168.19.129:       192.168.19.1:       ESTABLISHED

tcp6              :::                   :::*                    LISTEN

tcp6              :::                   :::*                    LISTEN

tcp6              :::                  :::*                    LISTEN

udp               127.0.0.1:           0.0.0.0:*

udp               192.168.19.129:    85.199.214.101:      ESTABLISHED

udp               192.168.19.129:    85.199.214.100:      ESTABLISHED

udp6              :::                 :::*

Active UNIX domain sockets (servers and established)

Proto RefCnt Flags       Type       State         I-Node   Path

unix        [ ACC ]     STREAM     LISTENING         /run/docker/libnetwork/2607d31c4b65ff68cf08c24cc6d5e4687dad654f9ec402872e98f8dcc79f448f.sock

unix        [ ACC ]     STREAM     LISTENING         private/rewrite

执行结果，除了上文的参数之外，还有Socket内容：

二、ss命令详解

ss是Socket Statistics的缩写

ss命令可以用来获取socket统计信息，它可以显示和netstat类似的内容。但是ss的优势在于它能够显示更详细的有关网络连接的状态信息，而比netstat更快速、更高效。
ss命令是iproute2软件包中的一员

使用场景一：查看当前服务器的网络连接数

[root@web129 ~]# ss -s

Total:  (kernel )

TCP:    (estab , closed , orphaned , synrecv , timewait /), ports 

Transport Total     IP        IPv6

*            -         -

RAW

UDP

TCP

INET

FRAG

使用场景2：查看所有打开的网络端口

[root@web129 ~]# ss -l

Netid State      Recv-Q Send-Q           Local Address:Port                            Peer Address:Port

nl    UNCONN                                    rtnl:                                  *

nl    UNCONN                                  rtnl:dockerd/                                 *

nl    UNCONN                                    rtnl:kernel                                      *

nl    UNCONN                                    rtnl:                                  *

nl    UNCONN                              tcpdiag:ss/                                     *

nl    UNCONN                               tcpdiag:kernel                                      *

nl    UNCONN                                    xfrm:kernel                                      *

nl    UNCONN                                    xfrm:dockerd/                                 *

nl    UNCONN                                 selinux:kernel                                      *

[root@web129 ~]# ss -pl #列出具体的程序名字
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
nl UNCONN 0 0 rtnl:1736442360 *
nl UNCONN 768 0 rtnl:dockerd/853 *

tcp LISTEN 0 128 :::http :::* users:(("httpd",pid=2493,fd=4),("httpd",pid=2492,fd=4),("httpd",pid=2491,fd=4),("httpd",pid=2490,fd=4),("httpd",pid=2489,fd=4),("httpd",pid=852,fd=4))
tcp LISTEN 0 128 :::ssh :::*

使用场景3：查看这台服务器上所有的Socket 连接

[root@web129 ~]# ss -a   #列出所有网络连接

Netid State      Recv-Q Send-Q           Local Address:Port                            Peer Address:Port

nl    UNCONN                                    rtnl:                                  *

nl    UNCONN                                  rtnl:dockerd/                                 *

nl    UNCONN                                    rtnl:kernel                                      *

nl    UNCONN                                    rtnl:                                  *

[root@web129 ~]# ss -ta   #查看TCP socket

State       Recv-Q Send-Q             Local Address:Port                              Peer Address:Port

LISTEN                                        *:ssh                                          *:*

LISTEN                                127.0.0.1:smtp                                         *:*

ESTAB                              192.168.19.129:ssh                               192.168.19.1:ratio-adp

ESTAB                              192.168.19.129:ssh                               192.168.19.1:cpq-wbem

LISTEN                                       :::http                                        :::*

LISTEN                                       :::ssh                                         :::*

LISTEN                                      :::smtp                                        :::*

[root@web129 ~]# ss -ua   #查看UDP  Socket

State       Recv-Q Send-Q             Local Address:Port                              Peer Address:Port

UNCONN                                  127.0.0.1:                                          *:*

ESTAB                              192.168.19.129:                            185.134.197.4:ntp

ESTAB                              192.168.19.129:                           193.228.143.12:ntp

ESTAB                              192.168.19.129:                           85.199.214.101:ntp

UNCONN                                        :::                                         :::*

[root@web129 ~]#

[root@web129 ~]# ss -wa   #查看RAW socket

State       Recv-Q Send-Q             Local Address:Port                              Peer Address:Port

[root@web129 ~]# ss -xa   #查看UNIX socket

Netid State      Recv-Q Send-Q           Local Address:Port                            Peer Address:Port

u_str LISTEN               /run/docker/libnetwork/2607d31c4b65ff68cf08c24cc6d5e4687dad654f9ec402872e98f8dcc79f448f.sock                                       *

u_str LISTEN                       private/rewrite                                       *

u_str LISTEN                        private/bounce                                       *

u_str LISTEN                         private/defer                                       *

u_str LISTEN                         private/trace                                       *