man in the middle attack ?

[Dr Beco <rcb@beco.cc>]

Dear linuxers,


Today I registered a lot of students in the class, and 4 hours later I
was in home and got a message one of them could not log in.

So I tried and got this message:


@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    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 the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
66:09:66:e3:e1:54:dc:65:e4:a4:74:99:c4:df:3e:ff.
Please contact your system administrator.
Add correct host key in /home/beco/.ssh/known_hosts to get rid of this message.
Offending key in /home/beco/.ssh/known_hosts:1
RSA host key for beco.poli.br has changed and you have requested
strict checking.
Host key verification failed.


What should I do, or where should I look, to understand this problem?

Can I log in with my account remotely to see the problem, or should I
better log in locally?


Thanks,
Beco.


-- 
Dr. Beco
A.I. research, Cognitive Scientist and Philosopher
Linux Counter #201942