ChromeOS - removing SSH known_hosts from Chromebook

By Leo Gaggl

July 22, 2015

One of the things that is not implemented in the Secure Shell Chrome extension is the ability to remove know_host fingerprints which alert you if the fingerprint for a specific IP address has changed.

However there are times when you upgrade a systems and this need to be done.

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@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
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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 a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
d6:be:12:7e:22:23:c3:e1:56:30:d6:cd:65:b7:ab:42.
Please contact your system administrator.
Add correct host key in /.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /.ssh/known_hosts:7
ECDSA host key for xxxxxxxxxxxxx.yyy.au has changed and you have requested strict checking.
Host key verification failed.
NaCl plugin exited with status code 255.
(R)econnect, (C)hoose another connection, or E(x)it?

Here is how to remove a known host fingerprint (from known_hosts) on a Chromebook.

You can find the index of the offending host entry reported by ssh if the connection fails (see above: “Offending ECDSA key in /.ssh/known_hosts:7”). Then you can open the JavaScript console (CTRL +Shift +J) and type the following into the console.

term_.command.removeKnownHostByIndex(INDEX);
Replace INDEX with the number obviously.

To clear all the known hosts:
term_.command.removeAllKnownHosts();