[root@www ~]# ssh 205.209.161.**
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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 the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
6c:74:2a:d5:ae:2b:76:51:*:*.
Please contact your system administrator.
Add correct host key in /root/.ssh/known_hosts to get rid of this message.
Offending key in /root/.ssh/known_hosts:20
RSA host key for 205.209.161.** has changed and you have requested strict checking.
Host key verification failed.

解决方法:
在正在操作的机器上执行
vi ~/.ssh/known_hosts
 
进入此目录,删除的  ip地址 111.111.111.111.**相关rsa的信息即可.
或者删除这个文件
cd ~/.ssh/
rm known_hosts