ssh链接linux主机时，可能出现“Host key verification failed.“的提示，ssh连接不成功。
可能的提示信息如下:
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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 ECDSA key sent by the remote host is
SHA256:/f+iAf5C4YHj5/JpyarKum7NUbqkeca1SMaj29dvj4c.
Please contact your system administrator.
Add correct host key in /Users/meinaozi/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /Users/meinaozi/.ssh/known_hosts:2
ECDSA host key for 121.43.235.24 has changed and you have requested strict checking.
Host key verification failed.
决方案是：vi ~/.ssh/known_hosts 删除与想要连接的主机相关的行；或者直接删除known_hosts这个文件。