测试TCP/UDP 端口联通性

最小化安装下检测tcp端口是否开放

#如果没安装网络工具，如telnet和 nmap，使用如下方式检测tcp端口是否开放
范例：检测谷歌域名服务是否开放 8.8.8.8 端口53
/dev/tcp/8.8.8.8/53 && echo 'open'

[root@centos-160 ~]# echo > /dev/tcp/8.8.8.8/53 && echo 'open'
open#如果没安装网络工具，如telnet和 nmap，使用如下方式检测tcp端口是否开放
范例：检测谷歌域名服务是否开放 8.8.8.8 端口53
/dev/tcp/8.8.8.8/53 && echo 'open'

[root@centos-160 ~]# echo > /dev/tcp/8.8.8.8/53 && echo 'open'
open

nc/telnet 命令测试tcp/udp端口

#nc 命令需安装nmap包
#nc 命令测试tcp端口
[root@centos-160 ~]# nc -znv 8.8.8.8 53
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to 8.8.8.8:53.
Ncat: 0 bytes sent, 0 bytes received in 0.10 seconds.

#nc 命令测试udp端口
[root@centos-160 ~]# nc -zunv 8.8.8.8 53
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to 8.8.8.8:53.
Ncat: UDP packet sent successfully
Ncat: 1 bytes sent, 0 bytes received in 2.02 seconds.

#telnet 命令需安装telnet包
[root@centos-160 ~]# telnet 8.8.8.8 53
Trying 8.8.8.8...
Connected to 8.8.8.8.
Escape character is '^]'.
Connection closed by foreign host.