linux下用telnet检测远程端口是否打开_linux telnet测试端口是否通

一、telnet检测某个远端端口是否通畅。

测试域名：
# telnet baidu.com 80
Trying 123.125.114.144...
Connected to baidu.com (123.125.114.144).         #==>出现Connected表示连通了，说
明百度的80端口开放的
Escape character is '^]'.             #==>按“ctrl+]”退出此地。
^]
telnet> quit
Connection closed.
测试IP地址：
# telnet 108.5.16.139 7506
Trying 108.5.16.139...
Connected to static-108-5-16-139.nycmny.fios.verizon.net (108.5.16.139).    #==>出
现Connected表示连通了，说明108.5.16.139的7506端口开放的
Escape character is '^]'.        #==>按“ctrl+]”退出此地
^]
telnet> quit
Connection closed.

如果写脚本通过telnet检查端口可以用下面的方法：

# echo -e "\n"|telnet baidu.com 80|grep Connected
Connection closed by foreign host.
Connected to baidu.com (123.125.114.144).

二、通过nmap来检查端口是否通畅

# nmap etiantian.org -p 80            
Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2012-07-22 17:22 PDT
Interesting ports on 211.100.98.99:
PORT   STATE SERVICE
80/tcp open  http
Nmap finished: 1 IP address (1 host up) scanned in 0.417 seconds

如果写脚本通过nmap检查端口可以用下面的方法：

PORT_COUNT=`nmap $ip_add  -p $port|grep open|wc -l`
[[ $PORT_COUNT -ge 1 ]] && echo "$ip_add $port is ok." || echo "$ip_add $port is unknown."

三、通过nc命令检查

# nc -w 10  8.8.8.8 53 && echo ok ||echo no  
ok