[root@a cron]# telnet www.baidu.com 80
Trying 115.239.211.112...
Connected to www.baidu.com. #显示connected，表示连接成功！
Escape character is '^]'.
^C^C^C^Z^Z^Z #按ctrl+c，ctrl+z，ctrl+D都不行，
Connection closed by foreign host.
[root@a cron]# telnet www.baidu.com 80
Trying 115.239.211.112...
Connected to www.baidu.com.
Escape character is '^]'.
HTTP/1.1 400 Bad Request
Connection closed by foreign host.
退出命令是ctrl+]后，输入quit退出
[root@a cron]# telnet www.bai.com 80
Trying 112.90.154.3...
Connected to www.bai.com.
Escape character is '^]'.
^] #按ctrl+]
telnet> quit
Connection closed.