ssh登陆服务器提示WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!

ubuntu@ubuntu:~$ ssh root@115.28.166.63
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@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
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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 ECDSA key sent by the remote host is
80:7e:80:1d:64:fa:aa:3f:fe:3b:3a:a3:03:3e:79:f4.
Please contact your system administrator.
Add correct host key in /home/ubuntu/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /home/ubuntu/.ssh/known_hosts:2
  remove with: ssh-keygen -f "/home/ubuntu/.ssh/known_hosts" -R 115.28.166.63
ECDSA host key for 115.28.166.63 has changed and you have requested strict checking.
Host key verification failed.

因为更换了服务器系统，导致一些特征码变了。以为是服务器的问题，sshd的设置都改烂了还不行，这是本地的问题，不是服务器的问题！

解决方法： 在本地～/.ssh/known_hosts中有登陆过的服务器的特征码，可以把里面的东西全删了，不要紧。然后就ok了。