Sometimes, when logging into another computer, you'll get a scary looking warning like:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: POSSIBLE DNS SPOOFING DETECTED! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ The RSA host key for example.com has changed, and the key for the corresponding IP address 192.168.1.100 is unknown. This could either mean that DNS SPOOFING is happening or the IP address for the host and its host key have changed at the same time. @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ 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 69:4e:bb:70:6a:61:e2:73:07:6f:b4:00:41:07:d8:9c. Please contact your system administrator. Add correct host key in /home/deploy/.ssh/known_hosts to get rid of this message. Offending key in /home/deploy/.ssh/known_hosts:1 Keyboard-interactive authentication is disabled to avoid man-in-the-middle attacks.
Although this looks bad, all it probably means is that the IP address of the computer you're trying to log into has changed. Because we use DHCP, this can happen every time a computer reboots. To fix the problem, delete the appropriate lines out of the ~/.ssh/known_hosts files.