telnet使用简介

端口开通,链接正常

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telnet 192.168.1.100 62715
Trying 192.168.1.100...
Connected to 192.168.1.100.
Escape character is '^]'.

链接成功,根据提示Escape character is '^]'.可知退出字符为'^]'(CTRL+])。此时输入其它字符不能使其退出,CTRL+C都不行。输入CTRL+]后会自动执行,进入命令模式,屏幕上出现telnet>字样。需要输入quit才可退出
Escape character提示是自定义的,使用参数-e即可

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telnet -e p 192.168.1.100 62715   #使用p字符
Telnet escape character is 'p'.
Trying 192.168.1.100...
Connected to 192.168.1.100.
Escape character is 'p'.

输入p,会出现telnet>字样,输入quit可退出

端口不通,无法链接

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telnet 192.168.1.100 62715
Trying 192.168.1.100...
telnet: connect to address 192.168.1.100: Connection refused

链接后,自动退出

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echo "" | telnet 192.168.1.100 62715

已成功连通端口并自动退出,显示如下信息

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Trying 192.168.1.100...
Connected to 192.168.1.100.
Escape character is '^]'.
Connection closed by foreign host.

如果端口未开放显示如下信息

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Trying 192.168.1.100...
telnet: connect to address 192.168.1.100: Connection refused

连接后,延时退出

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sleep 2 | telnet 192.168.1.100 62715

sleep 2使得telnet输出结果后,停留2秒后退出命令模式。

参考资料

http://www.linuxidc.com/Linux/2017-06/145164.htm
https://www.linuxprobe.com/chapter-09.html