telnet使用简介

端口开通,链接正常

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

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

1
2
3

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

1	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

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

1 2	Trying 192.168.1.100... telnet: connect to address 192.168.1.100: Connection refused

连接后，延时退出

1	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