netstat命令，一文搞懂
前言
后臺(tái)開發(fā)，netstat命令總是繞不過，不僅工作中經(jīng)常用過，面試也是考的多。netstat命令，對(duì)應(yīng)的選項(xiàng)比較多，功能比較強(qiáng)大。netstat 常用來查看，后臺(tái)服務(wù)進(jìn)程的相關(guān)狀態(tài)。
netstat 可以用來打印網(wǎng)絡(luò)連接、路由表、連接的數(shù)據(jù)統(tǒng)計(jì)。下面我們來學(xué)習(xí)一下。
打印所有連接
使用 -a，列出所有連接。
[root@VM-16-9-centos ~]# netstat -a
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:ssh 0.0.0.0:* LISTEN
tcp 0 0 VM-16-9-centos:49326 169.254.0.55:lsi-bobcat ESTABLISHED
tcp 0 52 VM-16-9-centos:ssh 119.137.1.7:20029 ESTABLISHED
tcp 0 0 VM-16-9-centos:ssh 113.110.224.255:63626 ESTABLISHED
tcp6 0 0 [::]:mysql [::]:* LISTEN
udp 0 0 0.0.0.0:bootpc 0.0.0.0:*
udp 0 0 VM-16-9-centos:ntp 0.0.0.0:*
udp 0 0 VM-16-9-centos:ntp 0.0.0.0:*
udp 0 0 0.0.0.0:38064 0.0.0.0:*
udp6 0 0 VM-16-9-centos:ntp [::]:*
udp6 0 0 VM-16-9-centos:ntp [::]:*
打印 TCP 或 UDP 連接
使用 -t 選項(xiàng)列出 TCP 協(xié)議的連接。
[root@VM-16-9-centos ~]# netstat -t
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 VM-16-9-centos:49326 169.254.0.55:lsi-bobcat ESTABLISHED
tcp 0 52 VM-16-9-centos:ssh 119.137.1.7:20029 ESTABLISHED
tcp 0 0 VM-16-9-centos:ssh 113.110.224.255:63626 ESTABLISHED
tcp 0 0 VM-16-9-centos:ssh vps-d395feee.vps.:39128 ESTABLISHED
使用 -u 選項(xiàng)列出 UDP 協(xié)議的連接。
[root@VM-16-9-centos ~]# netstat -u
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State 禁用反向域名解析
使用 -n 選項(xiàng)禁用域名解析功能，這樣可以加快查找速度。
[root@VM-16-9-centos ~]# netstat -n
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 172.17.16.9:49326 169.254.0.55:5574 ESTABLISHED
tcp 0 52 172.17.16.9:22 119.137.1.7:20029 ESTABLISHED
tcp 0 0 172.17.16.9:22 113.110.224.255:63626 ESTABLISHED
tcp 0 0 172.17.16.9:52236 169.254.0.4:80 TIME_WAIT 顯示對(duì)應(yīng)的程序識(shí)別碼和程序名稱
使用 -p 選項(xiàng)列出正在監(jiān)聽的套接字。
[root@VM-16-9-centos ~]# netstat -p
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 VM-16-9-centos:49326 169.254.0.55:lsi-bobcat ESTABLISHED 1400/YDService
tcp 0 52 VM-16-9-centos:ssh 119.137.1.7:20029 ESTABLISHED 22131/sshd: root@pt
tcp 0 0 VM-16-9-centos:ssh host-188-14-121-2:55529 TIME_WAIT -
tcp 0 0 VM-16-9-centos:ssh 113.110.224.255:63626 ESTABLISHED 32201/sshd: root@pt 打印監(jiān)聽中的連接
使用 -l 選項(xiàng)列出正在監(jiān)聽的套接字。
[root@VM-16-9-centos ~]# netstat -l
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:ssh 0.0.0.0:* LISTEN
tcp6 0 0 [::]:mysql [::]:* LISTEN
udp 0 0 0.0.0.0:bootpc 0.0.0.0:*
停下來，花30秒時(shí)間，欣賞一幅美麗的歐式建筑。建筑就像小時(shí)候童話里的，看著感覺心情舒暢。接下來接著學(xué)。
打印連接進(jìn)程信息
使用 -p 選項(xiàng)查看進(jìn)程信息。
[root@VM-16-9-centos ~]# netstat -p
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 VM-16-9-centos:49326 169.254.0.55:lsi-bobcat ESTABLISHED 1400/YDService
tcp 0 0 VM-16-9-centos:48680 169.254.0.55:webcache TIME_WAIT -
tcp 0 52 VM-16-9-centos:ssh 119.137.1.7:20029 ESTABLISHED 22131/sshd: root@pt
tcp 0 0 VM-16-9-centos:ssh 113.110.224.255:63626 ESTABLISHED 32201/sshd: root@pt
tcp 0 0 VM-16-9-centos:ssh host-188-14-121-2:56025 ESTABLISHED 10384/sshd: unknown 打印網(wǎng)絡(luò)工作信息統(tǒng)計(jì)表
使用 -s 選項(xiàng)查看進(jìn)程信息(只展示部分結(jié)果)。
[root@VM-16-9-centos ~]# netstat -s
Ip:
7502855 total packets received
0 forwarded
0 incoming packets discarded
7502837 incoming packets delivered
7624338 requests sent out
40 dropped because of missing route
Icmp:
938052 ICMP messages received
147 input ICMP message failed.
ICMP input histogram:
destination unreachable: 411
timeout in transit: 8
redirects: 2
echo requests: 937623
echo replies: 7
timestamp request: 1
946258 ICMP messages sent
0 ICMP messages failed
ICMP output histogram:
destination unreachable: 8634
echo replies: 937623
timestamp replies: 1
打印網(wǎng)絡(luò)接口
使用 -i 選項(xiàng)查看進(jìn)程信息。
[root@VM-16-9-centos ~]# netstat -i
Kernel Interface table
Iface MTU RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0 1500 7825094 0 0 0 7712988 0 0 0 BMRU
lo 65536 10230 0 0 0 10230 0 0 0 LRU 持續(xù)輸出信息
使用 -c 選項(xiàng)查看進(jìn)程信息。
[root@VM-16-9-centos ~]# netstat -c
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 VM-16-9-centos:49326 169.254.0.55:lsi-bobcat ESTABLISHED
tcp 0 52 VM-16-9-centos:ssh 119.137.1.7:20029 ESTABLISHED
tcp 0 0 VM-16-9-centos:ssh vps-d395feee.vps.:39442 ESTABLISHED
tcp 0 0 VM-16-9-centos:ssh 113.110.224.255:63626 ESTABLISHED
tcp 0 0 VM-16-9-centos:52660 169.254.0.4:http TIME_WAIT
tcp 0 0 VM-16-9-centos:ssh b3d278e1.virtua.c:35113 TIME_WAIT
tcp 0 0 VM-16-9-centos:ssh 58.230.147.230:56693 TIME_WAIT
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags Type State I-Node Path
unix 3 [ ] DGRAM 7444 /run/systemd/notify
根據(jù)進(jìn)程pid查端口
利用 grep 命令，通過進(jìn)程 pid 查出監(jiān)聽端口。
[root@VM-16-9-centos test]# netstat -nap|grep 12178
tcp6 0 0 :::8888 :::* LISTEN 12178/gin 根據(jù)端口查進(jìn)程
利用 grep 命令，通過監(jiān)聽端口查出進(jìn)程 pid 。
[root@VM-16-9-centos test]# netstat -nap|grep 8888
tcp6 0 0 :::8888 :::* LISTEN 12178/gin 統(tǒng)計(jì)網(wǎng)絡(luò)socket狀態(tài)
借助 awk 命令，統(tǒng)計(jì)socket狀態(tài)對(duì)應(yīng)的個(gè)數(shù)。
[test]# netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'
ESTABLISHED 5
TIME_WAIT 2 絮叨
netstat命令不難，但是選項(xiàng)比較多，工作中也常用，務(wù)必要掌握。這篇文章可以用作為大家 netstat 參考手冊(cè)。
希望這篇文章能幫助到大家，下期再會(huì)!
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