linux中查询端口占用情况

Netstat 是一款命令行工具，可用于列出系统上所有的网络套接字连接情况，包括 tcp, udp 以及 unix 套接字，另外它还能列出处于监听状态（即等待接入请求）的套接字。如果你想确认系统上的 Web 服务有没有起来，你可以查看80端口有没有打开。以上功能使 netstat 成为网管和系统管理员的必备利器。

一、netstat -anp |grep 9074

[webuser@10-6-5-95 ~]$ netstat -anp |grep 9074
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
tcp        0      0 :::9074                     :::*                        LISTEN      22177/java

二、列出所有当前的连接。使用 -a 选项即可

$ netstat -a

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 enlightened:domain *:* LISTEN
tcp 0 0 localhost:ipp *:* LISTEN
tcp 0 0 enlightened.local:54750 li240-5.members.li:http ESTABLISHED
tcp 0 0 enlightened.local:49980 del01s07-in-f14.1:https ESTABLISHED
tcp6 0 0 ip6-localhost:ipp [::]:* LISTEN
udp 0 0 enlightened:domain *:*
udp 0 0 *:bootpc *:*
udp 0 0 enlightened.local:ntp *:*
udp 0 0 localhost:ntp *:*
udp 0 0 *:ntp *:*
udp 0 0 *:58570 *:*
udp 0 0 *:mdns *:*
udp 0 0 *:49459 *:*
udp6 0 0 fe80::216:36ff:fef8:ntp [::]:*
udp6 0 0 ip6-localhost:ntp [::]:*
udp6 0 0 [::]:ntp [::]:*
udp6 0 0 [::]:mdns [::]:*
udp6 0 0 [::]:63811 [::]:*
udp6 0 0 [::]:54952 [::]:*
Active UNIX domain sockets (servers and established)
Proto RefCnt Flags Type State I-Node Path
unix 2 [ ACC ] STREAM LISTENING 12403 @/tmp/dbus-IDgfj3UGXX
unix 2 [ ACC ] STREAM LISTENING 40202 @/dbus-vfs-daemon/socket-6nUC6CCx

三、只列出 TCP 或 UDP 协议的连接
使用 -t 选项列出 TCP 协议的连接：

$ netstat -at
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 enli
4000
ghtened:domain *:* LISTEN
tcp 0 0 localhost:ipp *:* LISTEN
tcp 0 0 enlightened.local:36310 del01s07-in-f24.1:https ESTABLISHED
tcp 0 0 enlightened.local:45038 a96-17-181-10.depl:http ESTABLISHED
tcp 0 0 enlightened.local:37892 ABTS-North-Static-:http ESTABLISHED
.....

使用 -u 选项列出 UDP 协议的连接：
$ netstat -au
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
udp 0 0 *:34660 *:*
udp 0 0 enlightened:domain *:*
udp 0 0 *:bootpc *:*
udp 0 0 enlightened.local:ntp *:*
udp 0 0 localhost:ntp *:*
udp 0 0 *:ntp *:*
udp6 0 0 fe80::216:36ff:fef8:ntp [::]:*
udp6 0 0 ip6-localhost:ntp [::]:*
udp6 0 0 [::]:ntp [::]:*

四、禁用反向域名解析，加快查询速度
默认情况下 netstat 会通过反向域名解析技术查找每个 IP 地址对应的主机名。这会降低查找速度。如果你觉得 IP 地址已经足够，而没有必要知道主机名，就使用 -n 选项禁用域名解析功能。

$ netstat -ant
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 127.0.1.1:53 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN
tcp 0 0 192.168.1.2:49058 173.255.230.5:80 ESTABLISHED
tcp 0 0 192.168.1.2:33324 173.194.36.117:443 ESTABLISHED
tcp6 0 0 ::1:631 :::* LISTEN

五、打印统计数据
netstat 可以打印出网络统计数据，包括某个协议下的收发包数量。

$ netstat -s
Ip:
32797 total packets received
0 forwarded
0 incoming packets discarded
32795 incoming packets delivered
29115 requests sent out
60 outgoing packets dropped
Icmp:
125 ICMP messages received
0 input ICMP message failed.
ICMP input histogram:
destination unreachable: 125
125 ICMP messages sent
0 ICMP messages failed
ICMP output histogram:
destination unreachable: 125
... OUTPUT TRUNCATED ...