Remove key from known_hosts

The simplest solution is:

rm -f .ssh/known_hosts

ssh will recreate the file again, but you lose key checking for other hosts!

Or, you can use:

ssh-keygen -R "hostname"

Or the ssh "man-in-the-middle" message should indicate which line of the known_hosts file has the offending fingerprint. Edit the file, jump to that line and delete it.

There is an ssh-keygen switch (-R) for this.

man ssh-keygen reads:

-R hostname

Removes all keys belonging to hostname from a known_hosts file. This option is useful to delete hashed hosts (see the -H option above).

sed -i '6d' ~/.ssh/known_hosts

Will modify the file ~/.ssh/known_hosts:6 , removing the 6th line.

In my opinion, using ssh-keygen -R is a better solution for an openssh power user, while your regular Linux admin would do better to keep his/her sed skills fresh by using the above method.