背景
在安装完openssh之后，还是不能解决登录的问题。报错信息如下：
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 ...
解决办法
重新针对目标ip生成ssh文件，就会将之前旧的文件重新存成.old文件。
ssh-keygen -R <host>
接着在重新使用ssh登录即可。