当两个设备第一次进行连接时，会把设备的公钥信息保存在~/.ssh/konwn_hosts中，后续再次连接时OpenSSH会核对公钥进行验证，如果被连接设备重装系统或者IP变更等原因都会导致公钥信息对不上从而报以下警告。

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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 Exxxxx19 key sent by the remote host is
SHA256:JAKJS+xQ8lQ/kUpxxxxxxxxyDNdgVg4IeF+NUeY.
Please contact your system administrator.
Add correct host key in /Users/xubingtao/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /Users/xubingtao/.ssh/known_hosts:40
Host key for 1.9xxxxxx1 has changed and you have requested strict checking.
Host key verification failed.

这个时候我们可以删掉~/.ssh/konwn_hosts文件中对应IP的密文公钥信息，可以手动删除或执行“ssh-keygen -R 具体ip地址”即可重新连接Linux服务器了。