问题：
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
SHA256:*****.
Please contact your system administrator.
Add correct host key in /root/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /root/.ssh/known_hosts:24
ECDSA host key for ****(ip地址) has changed and you have requested strict checking.
Host key verification failed.
原因：密钥登录服务器时，由于目标服务器的密钥已经改变，但是本机存储的密钥还没有更新。
解决办法：直接打开本机的vim /home/***/.ssh/known_hosts，将已有的IP的密钥那一行，直接删除，重新连接即可。
