在运维过程中，常常会telnet某个ip端口，如果 能telnet通，怎么退出呢 ？
1、telnet 63.172.25.18 6463 回车
Trying 63.172.25.18...
Connected to 63.172.25.18 (63.172.25.18).
Escape character is '^]'.
2、ctrl + ] 回车
telnet>
3、? 回车
close close current connection
logout forcibly logout remote user and close the connection
display display operating parameters
mode try to enter line or character mode ('mode ?' for more)
open connect to a site
quit exit telnet
send transmit special characters ('send ?' for more)
set set operating parameters ('set ?' for more)
unset unset operating parameters ('unset ?' for more)
status print status information
toggle toggle operating parameters ('toggle ?' for more)
slc change state of special charaters ('slc ?' for more)
auth turn on (off) authentication ('auth ?' for more)
encrypt turn on (off) encryption ('encrypt ?' for more)
forward turn on (off) credential forwarding ('forward ?' for more)
z suspend telnet
! invoke a subshell
environ change environment variables ('environ ?' for more)
? print help information
4、quit 回车
Connection closed.