今天在使用linux的时候，要查看端口号，但是不知道要使用哪一个命令所以就学习了一下，原来是使用netstat，接下来给大家一起来学习。
一、netstat介绍
1.1、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。
Netstat 是一款命令行工具，可用于列出系统上所有的网络套接字连接情况，包括 tcp, udp 以及 unix 套接字，另外它还能列出处于监听状态（即等待接入请求）的套接字。
如果你想确认系统上的 Web 服务有没有起来，你可以查看80端口有没有打开。以上功能使 netstat 成为网管和系统管理员的必备利器。
在linux终端中输入netstat：
分析： 从上面可以看出，可以分为两个部分：
一个是Active Internet connections，称为有源TCP连接，其中"Recv-Q"和"Send-Q"指%0A的是接收队列和发送队列。这些数字一般都应该是0。如果不是则表示软件包正在队列中堆积。这种情况只能在非常少的情况见到。
另一个是Active UNIX domain sockets，称为有源Unix域套接口(和网络套接字一样，但是只能用于本机通信，性能可以提高一倍)。
Proto显示连接使用的协议,RefCnt表示连接到本套接口上的进程号,Types显示套接口的类型,State显示套接口当前的状态,Path表示连接到套接口的其它进程使用的路径名。
1.2、常用的参数
-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 查看进程信息-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。提示：LISTEN和LISTENING的状态只有用-a或者-l才能看到
二、netstat使用实例
2.1、显示所有的端口（包括监听未监听）
1) 列出所有端口 netstat -a
当我们加上-n的时候就禁止端口使用别名了,比如上面的mysql它的端口号是3306
2) 列出所有 tcp 端口 netstat -at
Active Internet connections (servers and established)Proto Recv-Q Send-Q Local Address ??????????Foreign Address ????????State ?????tcp ???????0 ?????0 localhost:mysql ????????0.0.0.0:* ??????????????LISTEN ????tcp ???????0 ?????0 0.0.0.0:hostmon ????????0.0.0.0:* ??????????????LISTEN ????tcp ???????0 ?????0 0.0.0.0:sunrpc ?????????0.0.0.0:* ??????????????LISTEN ????tcp ???????0 ?????0 udzyh1:domain ??????????0.0.0.0:* ??????????????LISTEN ????tcp ???????0 ?????0 0.0.0.0:ssh ????????????0.0.0.0:* ??????????????LISTEN ????tcp ???????0 ?????0 localhost:ipp ??????????0.0.0.0:* ??????????????LISTEN ????tcp ???????0 ?????0 0.0.0.0:37247 ??????????0.0.0.0:* ??????????????LISTEN ????tcp ???????0 ?????1 udzyh1:945 ?????????????1.0.0.3:nfs ????????????SYN_SENT ??tcp ???????0 ?????1 udzyh1:945 ?????????????1.0.0.3:nfs ????????????SYN_SENT ??tcp6 ??????0 ?????0 [::]:hostmon ???????????[::]:* ?????????????????LISTEN ????tcp6 ??????0 ?????0 [::]:sunrpc ????????????[::]:* ?????????????????LISTEN ????tcp6 ??????0 ?????0 [::]:ssh ???????????????[::]:* ?????????????????LISTEN ????tcp6 ??????0 ?????0 ip6-localhost:ipp ??????[::]:* ?????????????????LISTEN ????tcp6 ??????0 ?????0 [::]:33729 ?????????????[::]:* ?????????????????LISTEN ????
3)列出所有 udp 端口 netstat -au
1 Active Internet connections (servers and established) 2 Proto Recv-Q Send-Q Local Address ??????????Foreign Address ????????State ??????3 udp ???????0 ?????0 0.0.0.0:ipp ????????????0.0.0.0:* ??????????????????????????4 udp ???????0 ?????0 0.0.0.0:950 ????????????0.0.0.0:* ??????????????????????????5 udp ???????0 ?????0 udzyh1:domain ??????????0.0.0.0:* ??????????????????????????6 udp ???????0 ?????0 localhost:domain ???????0.0.0.0:* ??????????????????????????7 udp ???????0 ?????0 0.0.0.0:bootps ?????????0.0.0.0:* ??????????????????????????8 udp ???????0 ?????0 0.0.0.0:bootpc ?????????0.0.0.0:* ??????????????????????????9 udp ???????0 ?????0 0.0.0.0:60485 ??????????0.0.0.0:* ?????????????????????????10 udp ???????0 ?????0 0.0.0.0:sunrpc ?????????0.0.0.0:* ?????????????????????????11 udp ???????0 ?????0 0.0.0.0:mdns ???????????0.0.0.0:* ?????????????????????????12 udp ???????0 ?????0 0.0.0.0:hostmon ????????0.0.0.0:* ?????????????????????????13 udp6 ??????0 ?????0 [::]:950 ???????????????[::]:* ????????????????????????????14 udp6 ??????0 ?????0 [::]:sunrpc ????????????[::]:* ????????????????????????????15 udp6 ??????0 ?????0 [::]:41132 ?????????????[::]:* ????????????????????????????16 udp6 ??????0 ?????0 [::]:mdns ??????????????[::]:* ????????????????????????????17 udp6 ??????0 ?????0 [::]:hostmon ???????????[::]:* ?
2.2、列出所有处于监听状态的Sockets
1)只显示监听端口 netstat -l
2)只列出所有监听 tcp 端口 netstat -lt
3)只列出所有监听 udp 端口 netstat -lu
4)只列出所有监听 UNIX 端口 netstat -lx
2.3、显示每个协议的统计信息
显示所有端口的统计信息 netstat -s
打印出网络统计数据，包括某个协议下的收发包数量。
Ip: ???Forwarding: 1 ???44825 total packets received ???1 with invalid addresses ???0 forwarded ???0 incoming packets discarded ???44016 incoming packets delivered ???49606 requests sent out ???80 outgoing packets dropped ???110382753 dropped because of missing routeIcmp: ???13821 ICMP messages received ???4791 input ICMP message failed ???ICMP input histogram: ???????destination unreachable: 13798 ???????echo requests: 7 ???????echo replies: 16 ???13868 ICMP messages sent ???0 ICMP messages failed ???ICMP output histogram: ???????destination unreachable: 13845 ???????echo requests: 16 ???????echo replies: 7IcmpMsg: ???????InType0: 16 ???????InType3: 13798 ???????InType8: 7 ???????OutType0: 7 ???????OutType3: 13845 ???????OutType8: 16Tcp: ???6871 active connection openings ???6 passive connection openings ???6833 failed connection attempts ???2 connection resets received ???0 connections established ???20654 segments received ???26166 segments sent out ???6838 segments retransmitted ???0 bad segments received ???2 resets sentUdp: ???5822 packets received ???213 packets to unknown port received ???0 packet receive errors ???2529 packets sent ???0 receive buffer errors ???0 send buffer errors ???IgnoredMulti: 3508UdpLite:TcpExt: ???1938 ICMP packets dropped because they were out-of-window ???107 ICMP packets dropped because socket was locked ???19 TCP sockets finished time wait in fast timer ???196 delayed acks sent ???1 delayed acks further delayed because of locked socket ???Quick ack mode was activated 4 times ???12 packets directly queued to recvmsg prequeue ???TCPDirectCopyFromPrequeue: 2 ???13426 packet headers predicted ???247 acknowledgments not containing data payload received ???6758 predicted acknowledgments ???1 congestion windows recovered without slow start after partial ack ???TCPTimeouts: 6736 ???3 connections aborted due to timeout ???TCPRetransFail: 16 ???TCPRcvCoalesce: 2012 ???TCPSpuriousRtxHostQueues: 13337 ???TCPAutoCorking: 3 ???TCPSynRetrans: 6750 ???TCPOrigDataSent: 6868 ???TCPKeepAlive: 189IpExt: ???InNoRoutes: 498 ???InMcastPkts: 4985 ???OutMcastPkts: 1483 ???InBcastPkts: 3508 ???OutBcastPkts: 10 ???InOctets: 25359234 ???OutOctets: 3397412 ???InMcastOctets: 415880 ???OutMcastOctets: 116579 ???InBcastOctets: 303775 ???OutBcastOctets: 460 ???InNoECTPkts: 57259 ???InECT0Pkts: 65
显示 TCP 或 UDP 端口的统计信息 netstat -st 或 -su
使用netstat -st
IcmpMsg: ???InType0: 16 ???InType3: 13828 ???InType8: 7 ???OutType0: 7 ???OutType3: 13875 ???OutType8: 16Tcp: ???6886 active connection openings ???6 passive connection openings ???6848 failed connection attempts ???2 connection resets received ???0 connections established ???20654 segments received ???26181 segments sent out ???6853 segments retransmitted ???0 bad segments received ???2 resets sentUdpLite:TcpExt: ???1942 ICMP packets dropped because they were out-of-window ???107 ICMP packets dropped because socket was locked ???19 TCP sockets finished time wait in fast timer ???196 delayed acks sent ???1 delayed acks further delayed because of locked socket ???Quick ack mode was activated 4 times ???12 packets directly queued to recvmsg prequeue ???TCPDirectCopyFromPrequeue: 2 ???13426 packet headers predicted ???247 acknowledgments not containing data payload received ???6758 predicted acknowledgments ???1 congestion windows recovered without slow start after partial ack ???TCPTimeouts: 6751 ???3 connections aborted due to timeout ???TCPRetransFail: 16 ???TCPRcvCoalesce: 2012 ???TCPSpuriousRtxHostQueues: 13367 ???TCPAutoCorking: 3 ???TCPSynRetrans: 6765 ???TCPOrigDataSent: 6868 ???TCPKeepAlive: 189IpExt: ???InNoRoutes: 498 ???InMcastPkts: 4986 ???OutMcastPkts: 1483 ???InBcastPkts: 3508 ???OutBcastPkts: 10 ???InOctets: 25361943 ???OutOctets: 3401852 ???InMcastOctets: 415949 ???OutMcastOctets: 116579 ???InBcastOctets: 303775 ???OutBcastOctets: 460 ???InNoECTPkts: 57290 ???InECT0Pkts: 65
2.4、在netstat输出中显示PID和进程名称netstat -p
netstat -p 可以与其它开关一起使用，就可以添加 “PID/进程名称” 到 netstat 输出中，这样 debugging 的时候可以很方便的发现特定端口运行的程序。
注意：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。
2.5、找出程序运行的端口（服务）
netstat -ap|grep -i ssh
并不是所有的进程都能找到，没有权限的会不显示，使用 root 权限查看所有的信息。
2.6、显示网络接口列表
netstat -i
显示详细信息，像是 ifconfig 使用 netstat -ie。输出信息与 ifconfig 输出的信息一样。
觉得不错的大佬点个“推荐”哦！
linux命令详解（一）netstat
原文地址：http://www.cnblogs.com/zhangyinhua/p/7488771.html