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
SHA256:**.
Please contact your system administrator.
Add correct host key in /root/.ssh/known_hosts to get rid of this message.
Offending RSA key in /root/.ssh/known_hosts:34
RSA host key for x.x.x.x has changed and you have requested strict checking.
Host key verification failed.
连接失败的原因，报错中说得很清楚，远程主机的key改变了，注释掉本机“/root/.ssh/known_hosts”中第34行的内容即可，重新连接会获取新的key，建立连接。
原文：http://blog.51cto.com/3091046/2287870