User:Erbingha/Host Identification Changed

Ever get this message when you use SSH?

root> ssh -l djgreen spider.ece.ncsu.edu

WARNING: 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 host key has just been changed. Please contact your system administrator. Add correct host key in /root/.ssh/known_hosts to get rid of this message. Agent forwarding is disabled to avoid attacks by corrupted servers. X11 forwarding is disabled to avoid attacks by corrupted servers. Are you sure you want to continue connecting (yes/no)? no root>

Each time you connect to a remote machine that machine presents an ID card (a public key) to you. The first time you connect you usually record what this ID card looks like so you can tell if some one might be pretending to be the remote machine you are trying to connect to.

This error message is informing you that the ID card that you have recorded and the ID card you have be presented don't match. Some of the reasons this might happen are:

The machine has been reinstalled and has a new ID card (most likely) The machine is the same, but has been issued a new ID card (perhaps) Someone is pretending to be the machine that you want to connect with and may eavesdrop on your connect. (least likely, but if you get this message a lot, inform us immediately).

--Dan