When ssh keys have changed on remote system and we still have former keys in our known_hosts file our system will warn us that probably we under man-in-the-middle attack or dns is spoofed.

known_hosts1.png

 

If we sure it normal situation ssh keys have changed we can fix this situation in the following way:

  • remove old key manually

remove line with old key – number of line to be removed are in output just after “:

Offending key in /home/user/.ssh/known_hosts:2

  • ┬áremove old key via ssh-keygen command

ssh-keygen -R hostname

or

ssh-keygen -R ip_address

e.g.

ssh-keygen -R www.danpol.net

/home/user/.ssh/known_hosts updated.
Original contents retained as /home/user/.ssh/known_hosts.old

  • ┬áremove via other tools like sed or others

 

dzbanek 2012-12-21