Linux netstat命令詳解

簡介

Netstat 命令用于顯示各種網絡相關信息，如網絡連接，路由表，接口狀態 (Interface Statistics)，masquerade 連接，多播成員 (Multicast Memberships) 等等。

輸出信息含義

執行netstat后，其輸出結果為

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

從整體上看，netstat的輸出結果可以分為兩個部分：

一個是Active Internet connections，稱為有源TCP連接，其中"Recv-Q"和"Send-Q"指%0A的是接收隊列和發送隊列。這些數字一般都應該是0。如果不是則表示軟件包正在隊列中堆積。這種情況只能在非常少的情況見到。

另一個是Active UNIX domain sockets，稱為有源Unix域套接口(和網絡套接字一樣，但是只能用于本機通信，性能可以提高一倍)。Proto顯示連接使用的協議,RefCnt表示連接到本套接口上的進程號,Types顯示套接口的類型,State顯示套接口當前的狀態,Path表示連接到套接口的其它進程使用的路徑名。

常見參數

-a (all)顯示所有選項，默認不顯示LISTEN相關 -t (tcp)僅顯示tcp相關選項 -u (udp)僅顯示udp相關選項 -n 拒絕顯示別名，能顯示數字的全部轉化成數字。-l 僅列出有在 Listen (監聽) 的服務狀態

-p 顯示建立相關鏈接的程序名 -r 顯示路由信息，路由表 -e 顯示擴展信息，例如uid等 -s 按各個協議進行統計 -c 每隔一個固定時間，執行該netstat命令。

提示：LISTEN和LISTENING的狀態只有用-a或者-l才能看到

實用命令實例

1. 列出所有端口 (包括監聽和未監聽的)

列出所有端口 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. 列出所有處于監聽狀態的 Sockets

只顯示監聽端口 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?????????????????*:*

只列出所有監聽 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

只列出所有監聽 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??????????????????*:*

只列出所有監聽 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. 顯示每個協議的統計信息

顯示所有端口的統計信息 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.
?.....

顯示 TCP 或 UDP 端口的統計信息 netstat -st 或 -su

#?netstat?-st?
#?netstat?-su

4. 在 netstat 輸出中顯示 PID 和進程名稱 netstat -p

netstat -p 可以與其它開關一起使用，就可以添加 “PID/進程名稱” 到 netstat 輸出中，這樣 debugging 的時候可以很方便的發現特定端口運行的程序。

#?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 輸出中不顯示主機，端口和用戶名 (host, port or user)

當你不想讓主機，端口和用戶名顯示，使用 netstat -n。將會使用數字代替那些名稱。

同樣可以加速輸出，因為不用進行比對查詢。

#?netstat?-an

如果只是不想讓這三個名稱中的一個被顯示，使用以下命令

#?netsat?-a?--numeric-ports
#?netsat?-a?--numeric-hosts
#?netsat?-a?--numeric-users

6. 持續輸出 netstat 信息

netstat 將每隔一秒輸出網絡信息。

#?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. 顯示系統不支持的地址族 (Address Families)

netstat?--verbose

在輸出的末尾，會有如下的信息

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. 顯示核心路由信息 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 顯示數字格式，不查詢主機名稱。

9. 找出程序運行的端口

并不是所有的進程都能找到，沒有權限的會不顯示，使用 root 權限查看所有的信息。

#?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??-

找出運行在指定端口的進程

#?netstat?-an?|?grep?':80'

10. 顯示網絡接口列表

#?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

顯示詳細信息，像是 ifconfig 使用 netstat -ie:

#?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

11. IP和TCP分析

查看連接某服務端口最多的的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各種狀態列表

wss8848@ubuntu:~$?netstat?-nat?|awk?'{print?$6}'
established)
Foreign
LISTEN
TIME_WAIT
ESTABLISHED
TIME_WAIT
SYN_SENT

先把狀態全都取出來,然后使用uniq -c統計，之后再進行排序。

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)

最后的命令如下:

netstat?-nat?|awk?'{print?$6}'|sort|uniq?-c|sort?-rn

分析access.log獲得訪問前10位的ip地址

awk?'{print?$1}'?access.log?|sort|uniq?-c|sort

　　審核編輯：湯梓紅

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