How to Fix an Offending SSH key

If you are trying to ssh onto a router, switch or server and you get the error message below

[marquk01@netlab ~\]$ ssh [email protected]
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    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
8e:55:56:16:d3:3d:22:8c:8f:db:57:2b:a3:af:85:69.
Please contact your system administrator.
Add correct host key in /home/marquk01/.ssh/known\_hosts to get rid of this message.
Offending key in /home/marquk01/.ssh/known\_hosts:25
RSA host key for 10.1.0.200 has changed and you have requested strict checking.
Host key verification failed.

You will be able to fix this, by running the perl script below (found on The Geek Stuff).

You will need to change the number according to number found on “Offending key” line

[marquk01@netlab ~\]$ perl -pi -e 's/\\Q$\_// if ($. == 25);' ~/.ssh/known\_hosts

Once you hit enter, you will be able to ssh without an issue:

[marquk01@netlab ~\]$ ssh [email protected]
The authenticity of host '10.1.0.200 (10.1.0.200)' can't be established.
RSA key fingerprint is 8e:55:56:16:d3:3d:22:8c:8f:db:57:2b:a3:af:85:69.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '10.1.0.200' (RSA) to the list of known hosts.
[email protected]'s password:

For more details please visit The Geek Stuff

It’s a great website, full of little nuggets :)