當你的重裝伺服器，或者更換IP地址會提示.ssh/known_hosts中的Key不匹配，例如下面的提示

$ ssh logs@120.132.144.48
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
99:9b:da:86:dd:8d:ae:46:66:00:e0:09:fb:c5:56:3d.
Please contact your system administrator.
Add correct host key in /home/neo/.ssh/known_hosts to get rid of this message.
Offending RSA key in /home/neo/.ssh/known_hosts:43
  remove with: ssh-keygen -f "/home/neo/.ssh/known_hosts" -R 172.12.14.48
RSA host key for 172.12.14.48 has changed and you have requested strict checking.
Host key verification failed.
			

打開/home/neo/.ssh/known_hosts檔案刪除43行即可，也同樣可以使用下面命令刪除

ssh-keygen -f "/home/neo/.ssh/known_hosts" -R 172.12.14.48
			

$ ssh-keygen -f "/home/neo/.ssh/known_hosts" -R 172.12.14.48
/home/neo/.ssh/known_hosts updated.
Original contents retained as /home/neo/.ssh/known_hosts.old