IF you get below message

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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 the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
88:26:99:fb:z5:1d:92:e5:z6:6e:t3:499c:99:af:90.
Please contact your system administrator.
Add correct host key in /home/username/.ssh/known_hosts to get rid of this message.
Offending key in /home/username/.ssh/known_hosts:9
RSA host key for 192.168.1.2 has changed and you have requested strict checking.
Host key verification failed.

Solution is remove the keys for that ip or hostname ,like below

$ssh-keygen -R 192.168.1.2

/home/username/.ssh/known_hosts updated.
Original contents retained as /home/username/.ssh/known_hosts.old

After above step now you can ssh to remote machine