Transfer (http://www.cnblogs.com/ggjucheng/archive/2012/01/08/2316661.html)
Introduction
Netstat command is used to display various network related information such as network connection, routing table, interface status (Interface Statistics), masquerade connection, Multicast Memberships and so on.
Meaning of output information
After executing netstat, its output is
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
Overall, the output of netstat can be divided into two parts:
One is Active Internet connections, called active TCP connections, where "Recv-Q" and "Send-Q" refer to the receive queue and send queue of %0A. These numbers should generally be 0. If not it means the package is piling up in the queue. This situation can only be seen in very rare cases.
The other is Active UNIX domain sockets, called Active UNIX domain sockets (same as network sockets, but only for native communication, with double the performance).
Proto displays the protocol used for the connection, RefCnt represents the process number connected to the socket, Types displays the type of the socket, State displays the current state of the socket, and Path represents the path name used by other processes connected to the socket.
Common parameters
-a (all) displays all options, default does not display LISTEN related
-t (tcp) only displays tcp related options
-u (udp) only displays udp related options
-n refuses to display aliases, can display all numbers converted into numbers.
-l List only services that are in Listen (listening)
-p Display the name of the program that established the relevant link
-r Display routing information, routing table
-e Display extended information, such as uid, etc.
-s Count according to each protocol
-c Execute the netstat command every fixed time.
Tip: The status of LISTEN and LISTENING can only be seen with -a or -l
Practical Command Examples
1. List all ports (including listening and non-listening)
list all ports netstat -a
# 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
列出所有 tcp 端口 netstat -at
# 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
列出所有 udp 端口 netstat -au
# 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 *:*
2. 列出所有处于监听状态的 Sockets
只显示监听端口 netstat -l
# 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 *:*
只列出所有监听 tcp 端口 netstat -lt
# 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
只列出所有监听 udp 端口 netstat -lu
# 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 *:*
只列出所有监听 UNIX 端口 netstat -lx
# 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
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
# 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. .....
显示 TCP 或 UDP 端口的统计信息 netstat -st 或 -su
# netstat -st # netstat -su
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。
# 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
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。
# netstat -an
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
# netsat -a --numeric-ports # netsat -a --numeric-hosts # netsat -a --numeric-users
6. 持续输出 netstat 信息
netstat 将每隔一秒输出网络信息。
# 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
7. 显示系统不支持的地址族 (Address Families)
netstat --verbose
在输出的末尾，会有如下的信息
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.
8. 显示核心路由信息 netstat -r
# 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
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。
# 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 -
找出运行在指定端口的进程
# netstat -an | grep ':80'
10. 显示网络接口列表
# 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
显示详细信息，像是 ifconfig 使用 netstat -ie:
# netstat -ie Kernel Interface table eth0 Link encap:Ethernet HWaddr 00:10:40:11:11:11 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
11. IP和TCP分析
查看连接某服务端口最多的的IP地址
wss8848@ubuntu:~$ netstat -nat | grep "192.168.1.15:22" |awk '{print $5}'|awk -F: '{print $1}'|sort|uniq -c|sort -nr|head -20
18 221.136.168.36
3 154.74.45.242
2 78.173.31.236
2 62.183.207.98
2 192.168.1.14
2 182.48.111.215
2 124.193.219.34
2 119.145.41.2
2 114.255.41.30
1 75.102.11.99
TCP各种状态列表
wss8848@ubuntu:~$ netstat -nat |awk '{print $6}'
established)
Foreign
LISTEN
TIME_WAIT
ESTABLISHED
TIME_WAIT
SYN_SENT
先把状态全都取出来,然后使用uniq -c统计，之后再进行排序。
wss8848@ubuntu:~$ 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)
The final command is as follows:
netstat -nat |awk '{print $6}'|sort|uniq -c|sort -rn
Analyze access.log to get the top 10 ip addresses
awk '{print $1}' access.log |sort|uniq -c|sort -nr|head -10
Reference: http://blog.maxiang.net/10-netstat-command-examples/139/