Use SSH to connect to the server:
$ ssh mtitek@localhost
You may get the following error:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
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:Dmz1/rPX9LcCQjFzNSvVsvB/rBBlYaVcp9rqGv9f1gU.
Please contact your system administrator.
Add correct host key in $HOME/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in $HOME/.ssh/known_hosts:3
ECDSA host key for localhost has changed and you have requested strict checking.
Host key verification failed.
To fix this error, open the file '$HOME/.ssh/known_hosts'
and delete the line corresponding to the host you are trying to connect to (localhost).