Linux netstat详解

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一、netstat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。

二、netstat使用

• 1、命令的一般格式

  netstat [选项]

• 2、参数介绍

  -a (all)显示所有选项，默认不显示LISTEN相关
  -t (tcp)仅显示tcp相关选项
  -u (udp)仅显示udp相关选项
  -n 拒绝显示别名，能显示数字的全部转化成数字。
  -l 仅列出有在 Listen (监听) 的服務状态
  
  -p 显示建立相关链接的程序名
  -r 显示路由信息，路由表
  -e 显示扩展信息，例如uid等
  -s 按各个协议进行统计
  -c 每隔一个固定时间，执行该netstat命令

• 3、实例

  • A、列出所有端口

    • 列出所有端口

      root@iZ235ubl1arZ:/home/yanmin/blog# netstat -a | more
      Active Internet connections (servers and established)
      Proto Recv-Q Send-Q Local Address           Foreign Address         State
      tcp        0      0 *:http                  *:*                     LISTEN
      tcp        0      0 *:ssh                   *:*                     LISTEN

    • 列出所有tcp端口

      root@iZ235ubl1arZ:/home/yanmin/blog# netstat -at
      Active Internet connections (servers and established)
      Proto Recv-Q Send-Q Local Address           Foreign Address         State
      tcp        0      0 *:http                  *:*                     LISTEN
      tcp        0      0 *:ssh                   *:*                     LISTEN
      tcp        0      0 121.41.120.65:http      140.205.201.20:35425    TIME_WAIT

    • 列出所有udp端口

      root@iZ235ubl1arZ:/home/yanmin/blog# netstat -au
      Active Internet connections (servers and established)
      Proto Recv-Q Send-Q Local Address           Foreign Address         State
      udp        0      0 121.41.120.65:ntp       *:*
      udp        0      0 iZ235ubl1arZ:ntp        *:*
      udp        0      0 localhost:ntp           *:*
      udp        0      0 *:ntp                   *:*
      udp6       0      0 [::]:ntp                [::]:*

• B、列出所有处于监听状态的Sockets

  • 只显示监听端口netstat -l

    root@iZ235ubl1arZ:/home/yanmin/blog# netstat -l
    Active Internet connections (only servers)
    Proto Recv-Q Send-Q Local Address           Foreign Address         State
    tcp        0      0 *:http                  *:*                     LISTEN
    tcp        0      0 *:ssh                   *:*                     LISTEN
    udp        0      0 121.41.120.65:ntp       *:*
    udp        0      0 iZ235ubl1arZ:ntp        *:*
    udp        0      0 localhost:ntp           *:*

  • 只列出所有监听tcp端口netstat -lt

    root@iZ235ubl1arZ:/home/yanmin/blog# netstat -lt
    Active Internet connections (only servers)
    Proto Recv-Q Send-Q Local Address           Foreign Address         State
    tcp        0      0 *:http                  *:*                     LISTEN
    tcp        0      0 *:ssh                   *:*                     LISTEN

  • 只列出所有监听udp端口 netstat -lu

    root@iZ235ubl1arZ:/home/yanmin/blog# netstat -lu
    Active Internet connections (only servers)
    Proto Recv-Q Send-Q Local Address           Foreign Address         State
    udp        0      0 121.41.120.65:ntp       *:*
    udp        0      0 iZ235ubl1arZ:ntp        *:*
    udp        0      0 localhost:ntp           *:*
    udp        0      0 *:ntp                   *:*
    udp6       0      0 [::]:ntp                [::]:*

  • 只列出所有监听UNIX端口 netstat -lx

    root@iZ235ubl1arZ:/home/yanmin/blog# netstat -lx
    Active UNIX domain sockets (only servers)
    Proto RefCnt Flags       Type       State         I-Node   Path
    unix  2      [ ACC ]     STREAM     LISTENING     9506     /var/run/nscd/socket
    unix  2      [ ACC ]     STREAM     LISTENING     8267     /var/run/dbus/system_bus_socket
    unix  2      [ ACC ]     SEQPACKET  LISTENING     7769     /run/udev/control
    unix  2      [ ACC ]     STREAM     LISTENING     7592     @/com/ubuntu/upstart

• C、在netstat 输出中显示PID和进程名称netstat -p

  root@iZ235ubl1arZ:/home/yanmin/blog# netstat -p
  Active Internet connections (w/o servers)
  Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
  tcp        0    316 121.41.120.65:ssh       58.246.62.146:54175     ESTABLISHED 17558/sshd: yanmin
  tcp        0      0 121.41.120.65:ssh       58.246.62.146:52592     ESTABLISHED 14538/sshd: yanmin
  Active UNIX domain sockets (w/o servers)
  Proto RefCnt Flags       Type       State         I-Node   PID/Program name    Path
  unix  10     [ ]         DGRAM                    8286     682/rsyslogd        /dev/log
  unix  3      [ ]         STREAM     CONNECTED     307127   17558/sshd: yanmin

• D、显示核心路由信息 netstat -r

  yanmin:blog yanmin$ netstat -r
  Routing tables
  
  Internet:
  Destination        Gateway            Flags        Refs      Use   Netif Expire
  default            10.96.150.1        UGSc           21        0     en0
  10.16/14           10.254.254.81      UGSc            0        0   utun1
  10.16.0.222/32     10.254.254.81      UGSc            1        0   utun1

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