weird ssh message

[WilliamWallace]

when i telnet to a compuer at school...and try to ssh back into my box (to see if ssh is working) i get this:




@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ warning: host authentication has changed! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!

someone could be eavsdropping on you right now (man_in_the_middle_attack)
is is also possible that the host key has been changed.
please contact your system administrator

Add correct host key in ~/.ssh/known_hosts
to get rid of this message.

password authentication disabled to avoid trojan horses

permission denied

Please contact your system administrator


what does this mean?? how can i fix it?

[Craig McPherson]

You probably changed your system's public key, probably by re-installing SSH. When you SSH to a machine, the client machine asks you to accept whether you believe the remote machine is who it says it is, by accepting its public key. If the remote machine switches to a different key, the client machine has to assume that the remove machine is a hostile system trying to impersonate the original remote machine.

Of curse, in your case, you just switched the system to a new public key probably without realizing that, but the client doesn't realize that and has to be safe.