[twobob]

TIP: If you are SSH'ing and your key has changed (This can be caused by your router updating amongst other, less secure, reasons)

You would recieve a big obvious warning from SSH
including "Kindles host key changed"

one solution is (allegedly): ssh-keygen -r {IP-Address}
For some reason this didn't work for me. (the command completed but I got an extra whitespace line in my file so...)

or simply vi /wherever/.ssh/known_hosts and (press) dd on the offending line and then (escape) :wq! to get out.
(That's what I did.)

also: sed -i ’{IP-Address}d’ /wherever/.ssh/known_hosts should do the trick (if you have sed)

Hope that helps.