netstat命令是什么？如何使用netstat命令？

    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

1 常用选项：

    -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 ：以数字显示IP和端口，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。

    -w：raw socket相关

2 -tan 显示所有tcp端口

[root@centos7 ~]# netstat -ant

Active Internet connections (servers and established)

Proto Recv-Q Send-Q Local Address Foreign Address State

tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN

tcp 0 0 192.168.122.1:53 0.0.0.0:* LISTEN

tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN

tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN

tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN

tcp 0 52 192.168.29.3:22 192.168.29.1:51029 ESTABLISHED

tcp 0 0 192.168.29.3:22 192.168.29.1:51180 ESTABLISHED

tcp6 0 0 :::111 :::* LISTEN

tcp6 0 0 :::22 :::* LISTEN

tcp6 0 0 ::1:631 :::* LISTEN

tcp6 0 0 ::1:25 :::*

3 显示所有udp端口 -uan

[root@centos7 ~]# netstat -anu

Active Internet connections (servers and established)

Proto Recv-Q Send-Q Local Address Foreign Address State

udp 0 0 0.0.0.0:5353 0.0.0.0:*

udp 0 0 0.0.0.0:47414 0.0.0.0:*

udp 0 0 192.168.122.1:53 0.0.0.0:*

udp 0 0 0.0.0.0:67 0.0.0.0:*

4 显示所有处于监听的tcp端口    -tnl

[root@centos7 ~]# netstat -tnl

Active Internet connections (only servers)

Proto Recv-Q Send-Q Local Address Foreign Address State

tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN

tcp 0 0 192.168.122.1:53 0.0.0.0:* LISTEN

tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN

tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN

tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN

tcp6 0 0 :::111 :::* LISTEN

tcp6 0 0 :::22 :::* LISTEN

tcp6 0 0 ::1:631 :::* LISTEN

tcp6 0 0 ::1:25 :::* LISTEN

5 显示所有处于监听状态的udp端口 -unl

[root@centos7 ~]# netstat -unl

Active Internet connections (only servers)

Proto Recv-Q Send-Q Local Address Foreign Address State

udp 0 0 0.0.0.0:5353 0.0.0.0:*

udp 0 0 0.0.0.0:47414 0.0.0.0:*

udp 0 0 0.0.0.0:20815 0.0.0.0:*

udp 0 0 192.168.122.1:53 0.0.0.0:*

udp 0 0 0.0.0.0:67 0.0.0.0:*

udp 0 0 0.0.0.0:68 0.0.0.0:*

udp 0 0 0.0.0.0:68 0.0.0.0:*

udp 0 0 0.0.0.0:9804 0.0.0.0:*

udp6 0 0 :::12799 :::*

udp6 0 0 :::37953 :::*

6 显示路由表 –rn

[root@centos7 ~]# netstat -nr

Kernel IP routing table

Destination Gateway Genmask Flags MSS Window irtt Iface

0.0.0.0 192.168.29.1 0.0.0.0 UG 0 0 0 ens33

192.168.29.0 0.0.0.0 255.255.255.0 U 0 0 0 ens33

192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0

[root@centos7 ~]# route -n

Kernel IP routing table

Destination Gateway Genmask Flags Metric Ref Use Iface

0.0.0.0 192.168.29.1 0.0.0.0 UG 100 0 0 ens33

192.168.29.0 0.0.0.0 255.255.255.0 U 100 0 0 ens33

192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0

7 显示每个协议的统计信息

（1）显示所有端口的统计信息 netstat -s

[root@centos7 ~]# netstat -s

Ip:

3808 total packets received

0 forwarded

0 incoming packets discarded

2444 incoming packets delivered

2254 requests sent out

32 outgoing packets dropped

Icmp:

676 ICMP messages received

0 input ICMP message failed.

ICMP input histogram:

destination unreachable: 148

echo replies: 528

717 ICMP messages sent

0 ICMP messages failed

ICMP output histogram:

destination unreachable: 148

echo request: 569

[……]

（2）显示 TCP 端口的统计信息 netstat -st

[root@centos7 ~]# netstat -st

IcmpMsg:

InType0: 528

InType3: 148

OutType3: 148

OutType8: 569

Tcp:

0 active connections openings

2 passive connection openings

0 failed connection attempts

0 connection resets received

2 connections established

1637 segments received

1418 segments send out

0 segments retransmited

0 bad segments received.

0 resets sent

（3）显示 UDP 端口的统计信息 netstat -su

[root@centos7 ~]# netstat -su

IcmpMsg:

InType0: 528

InType3: 148

OutType3: 148

OutType8: 569

Udp:

0 packets received

140 packets to unknown port received.

0 packet receive errors

169 packets sent

0 receive buffer errors

0 send buffer errors

UdpLite:

IpExt:

InMcastPkts: 27

OutMcastPkts: 33

InBcastPkts: 766

InOctets: 410294

OutOctets: 432666

InMcastOctets: 4963

OutMcastOctets: 5444

InBcastOctets: 179503

InNoECTPkts: 3848

8 显示 PID 和进程名称 netstat -p

[root@centos7 ~]# netstat -p

Active Internet connections (w/o servers)

Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name

tcp 0 52 centos7.3.local:ssh gateway:51029 ESTABLISHED 1552/sshd: root@pts

tcp 0 0 centos7.3.local:ssh gateway:51180 ESTABLISHED 1854/sshd: root@pts

Active UNIX domain sockets (w/o servers)

Proto RefCnt Flags Type State I-Node PID/Program name Path

unix 2 [ ] DGRAM 8520 1/systemd /run/systemd/notify

unix 2 [ ] DGRAM 8522 1/systemd /run/systemd/cgroups-agent

unix 5 [ ] DGRAM 8542 1/systemd /run/systemd/journal/socket

unix 28 [ ] DGRAM 8544 1/systemd /dev/log

unix 2 [ ] DGRAM 11419 1/systemd /run/systemd/shutdownd

unix 3 [ ] STREAM CONNECTED 23993 1276/ibus-x11

 

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