acf@vermilion:~$ ssh acf@kremvax.acfsys.net
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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 RSA key sent by the remote host is
07:53:24:ad:ad:5b:7a:ac:e8:48:e3:f2:25:fe:b7:9d.
Please contact your system administrator.
Add correct host key in /home/acf/.ssh/known_hosts to get rid of this message.
Offending RSA key in /home/acf/.ssh/known_hosts:3
  remove with: ssh-keygen -f "/home/acf/.ssh/known_hosts" -R kremvax.acfsys.net
RSA host key for kremvax.acfsys.net has changed and you have requested strict checking.
Host key verification failed.
acf@vermilion:~$