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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。
输出信息含义
执行netstat后，其输出结果为
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Active?Internet?connections?(w/o?servers) Proto?Recv-Q?Send-Q?Local?Address?Foreign?Address?State tcp?0?2?210.34.6.89:telnet?210.34.6.96:2873?ESTABLISHED tcp?296?0?210.34.6.89:1165?210.34.6.84:netbios-ssn?ESTABLISHED tcp?0?0?localhost.localdom:9001?localhost.localdom:1162?ESTABLISHED tcp?0?0?localhost.localdom:1162?localhost.localdom:9001?ESTABLISHED tcp?0?80?210.34.6.89:1161?210.34.6.10:netbios-ssn?CLOSE Active?UNIX?domain?sockets?(w/o?servers) Proto?RefCnt?Flags?Type?State?I-Node?Path unix?1?[?]?STREAM?CONNECTED?16178?@000000dd unix?1?[?]?STREAM?CONNECTED?16176?@000000dc unix?9?[?]?DGRAM?5292?/dev/log unix?1?[?]?STREAM?CONNECTED?16182?@000000df
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从整体上看，netstat的输出结果可以分为两个部分：
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。
常见参数
-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 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。
提示：LISTEN和LISTENING的状态只有用-a或者-l才能看到
实用命令实例
1. 列出所有端口 (包括监听和未监听的)
列出所有端口 netstat -a
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#?netstat?-a?|?more ?Active?Internet?connections?(servers?and?established) ?Proto?Recv-Q?Send-Q?Local?Address???????????Foreign?Address?????????State ?tcp????????0??????0?localhost:30037?????????*:*?????????????????????LISTEN ?udp????????0??????0?*:bootpc????????????????*:* ? Active?UNIX?domain?sockets?(servers?and?established) ?Proto?RefCnt?Flags???????Type???????State?????????I-Node???Path ?unix??2??????[?ACC?]?????STREAM?????LISTENING?????6135?????/tmp/.X11-unix/X0 ?unix??2??????[?ACC?]?????STREAM?????LISTENING?????5140?????/var/run/acpid.socket
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列出所有 tcp 端口 netstat -at
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#?netstat?-at ?Active?Internet?connections?(servers?and?established) ?Proto?Recv-Q?Send-Q?Local?Address???????????Foreign?Address?????????State ?tcp????????0??????0?localhost:30037?????????*:*?????????????????????LISTEN ?tcp????????0??????0?localhost:ipp???????????*:*?????????????????????LISTEN ?tcp????????0??????0?*:smtp??????????????????*:*?????????????????????LISTEN ?tcp6???????0??????0?localhost:ipp???????????[::]:*??????????????????LISTEN
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列出所有 udp 端口 netstat -au
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#?netstat?-au ?Active?Internet?connections?(servers?and?established) ?Proto?Recv-Q?Send-Q?Local?Address???????????Foreign?Address?????????State ?udp????????0??????0?*:bootpc????????????????*:* ?udp????????0??????0?*:49119?????????????????*:* ?udp????????0??????0?*:mdns??????????????????*:*
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2. 列出所有处于监听状态的 Sockets
只显示监听端口 netstat -l
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#?netstat?-l ?Active?Internet?connections?(only?servers) ?Proto?Recv-Q?Send-Q?Local?Address???????????Foreign?Address?????????State ?tcp????????0??????0?localhost:ipp???????????*:*?????????????????????LISTEN ?tcp6???????0??????0?localhost:ipp???????????[::]:*??????????????????LISTEN ?udp????????0??????0?*:49119?????????????????*:*
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只列出所有监听 tcp 端口 netstat -lt
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#?netstat?-lt ?Active?Internet?connections?(only?servers) ?Proto?Recv-Q?Send-Q?Local?Address???????????Foreign?Address?????????State ?tcp????????0??????0?localhost:30037?????????*:*?????????????????????LISTEN ?tcp????????0??????0?*:smtp??????????????????*:*?????????????????????LISTEN ?tcp6???????0??????0?localhost:ipp???????????[::]:*??????????????????LISTEN
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只列出所有监听 udp 端口 netstat -lu
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#?netstat?-lu ?Active?Internet?connections?(only?servers) ?Proto?Recv-Q?Send-Q?Local?Address???????????Foreign?Address?????????State ?udp????????0??????0?*:49119?????????????????*:* ?udp????????0??????0?*:mdns??????????????????*:*
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只列出所有监听 UNIX 端口 netstat -lx
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#?netstat?-lx ?Active?UNIX?domain?sockets?(only?servers) ?Proto?RefCnt?Flags???????Type???????State?????????I-Node???Path ?unix??2??????[?ACC?]?????STREAM?????LISTENING?????6294?????private/maildrop ?unix??2??????[?ACC?]?????STREAM?????LISTENING?????6203?????public/cleanup ?unix??2??????[?ACC?]?????STREAM?????LISTENING?????6302?????private/ifmail ?unix??2??????[?ACC?]?????STREAM?????LISTENING?????6306?????private/bsmtp
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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
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#?netstat?-s ?Ip: ?11150?total?packets?received ?1?with?invalid?addresses ?0?forwarded ?0?incoming?packets?discarded ?11149?incoming?packets?delivered ?11635?requests?sent?out ?Icmp: ?0?ICMP?messages?received ?0?input?ICMP?message?failed. ?Tcp: ?582?active?connections?openings ?2?failed?connection?attempts ?25?connection?resets?received ?Udp: ?1183?packets?received ?4?packets?to?unknown?port?received. ?.....
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显示 TCP 或 UDP 端口的统计信息 netstat -st 或 -su
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#?netstat?-st? #?netstat?-su
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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。
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#?netstat?-pt ?Active?Internet?connections?(w/o?servers) ?Proto?Recv-Q?Send-Q?Local?Address???????????Foreign?Address?????????State???????PID/Program?name ?tcp????????1??????0?ramesh-laptop.loc:47212?192.168.185.75:www????????CLOSE_WAIT??2109/firefox ?tcp????????0??????0?ramesh-laptop.loc:52750?lax:www?ESTABLISHED?2109/firefox
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5. 在 netstat 输出中不显示主机，端口和用户名 (host, port or user)
当你不想让主机，端口和用户名显示，使用 netstat -n。将会使用数字代替那些名称。
同样可以加速输出，因为不用进行比对查询。
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#?netstat?-an
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如果只是不想让这三个名称中的一个被显示，使用以下命令
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#?netsat?-a?--numeric-ports #?netsat?-a?--numeric-hosts #?netsat?-a?--numeric-users
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6. 持续输出 netstat 信息
netstat 将每隔一秒输出网络信息。
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#?netstat?-c ?Active?Internet?connections?(w/o?servers) ?Proto?Recv-Q?Send-Q?Local?Address???????????Foreign?Address?????????State ?tcp????????0??????0?ramesh-laptop.loc:36130?101-101-181-225.ama:www?ESTABLISHED ?tcp????????1??????1?ramesh-laptop.loc:52564?101.11.169.230:www??????CLOSING ?tcp????????0??????0?ramesh-laptop.loc:43758?server-101-101-43-2:www?ESTABLISHED ?tcp????????1??????1?ramesh-laptop.loc:42367?101.101.34.101:www??????CLOSING ?^C
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7. 显示系统不支持的地址族 (Address Families)
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netstat?--verbose
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在输出的末尾，会有如下的信息
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netstat:?no?support?for?`AF?IPX'?on?this?system. netstat:?no?support?for?`AF?AX25'?on?this?system. netstat:?no?support?for?`AF?X25'?on?this?system. netstat:?no?support?for?`AF?NETROM'?on?this?system.
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8. 显示核心路由信息 netstat -r
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#?netstat?-r ?Kernel?IP?routing?table ?Destination?????Gateway?????????Genmask?????????Flags???MSS?Window??irtt?Iface ?192.168.1.0?????*???????????????255.255.255.0???U?????????0?0??????????0?eth2 ?link-local??????*???????????????255.255.0.0?????U?????????0?0??????????0?eth2 ?default?????????192.168.1.1?????0.0.0.0?????????UG????????0?0??????????0?eth2
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注意：使用 netstat -rn 显示数字格式，不查询主机名称。
9. 找出程序运行的端口
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。
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#?netstat?-ap?|?grep?ssh ?tcp????????1??????0?dev-db:ssh???????????101.174.100.22:39213????????CLOSE_WAIT??- ?tcp????????1??????0?dev-db:ssh???????????101.174.100.22:57643????????CLOSE_WAIT??-
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找出运行在指定端口的进程
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#?netstat?-an?|?grep?':80'
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10. 显示网络接口列表
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#?netstat?-i ?Kernel?Interface?table ?Iface???MTU?Met???RX-OK?RX-ERR?RX-DRP?RX-OVR????TX-OK?TX-ERR?TX-DRP?TX-OVR?Flg ?eth0???????1500?0?????????0??????0??????0?0?????????????0??????0??????0??????0?BMU ?eth2???????1500?0?????26196??????0??????0?0?????????26883??????6??????0??????0?BMRU ?lo????????16436?0?????????4??????0??????0?0?????????????4??????0??????0??????0?LRU
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显示详细信息，像是 ifconfig 使用 netstat -ie:
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#?netstat?-ie ?Kernel?Interface?table ?eth0??????Link?encap:Ethernet??HWaddr?004011:11 ?UP?BROADCAST?MULTICAST??MTU:1500??Metric:1 ?RX?packets:0?errors:0?dropped:0?overruns:0?frame:0 ?TX?packets:0?errors:0?dropped:0?overruns:0?carrier:0 ?collisions:0?txqueuelen:1000 ?RX?bytes:0?(0.0?B)??TX?bytes:0?(0.0?B) ?Memory:f6ae0000-f6b00000
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11. IP和TCP分析
查看连接某服务端口最多的的IP地址
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wss8848@ubuntu:~$?netstat?-nat?|?grep?"192.168.1.15:22"?|awk?'{print?$5}'|awk?-F:?'{print?$1}'|sort|uniq?-c|sort?-nr|head?-20
18?221.136.168.36
3?154.74.45.242
2?78.173.31.236
2?62.183.207.98
2?192.168.1.14
2?182.48.111.215
2?124.193.219.34
2?119.145.41.2
2?114.255.41.30
1?75.102.11.99
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TCP各种状态列表
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wss8848@ubuntu:~$?netstat?-nat?|awk?'{print?$6}'
established)
Foreign
LISTEN
TIME_WAIT
ESTABLISHED
TIME_WAIT
SYN_SENT
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先把状态全都取出来,然后使用uniq -c统计，之后再进行排序。
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wss8848@ubuntu:~$?netstat?-nat?|awk?'{print?$6}'|sort|uniq?-c
143?ESTABLISHED
1?FIN_WAIT1
1?Foreign
1?LAST_ACK
36?LISTEN
6?SYN_SENT
113?TIME_WAIT
1?established)
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最后的命令如下:
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netstat?-nat?|awk?'{print?$6}'|sort|uniq?-c|sort?-rn
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分析access.log获得访问前10位的ip地址
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awk?'{print?$1}'?access.log?|sort|uniq?-c|sort
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