• Tag Archives ssh known_hosts
  • SSH Ignore (un)known host keys

    Sometimes, you wish that SSH would just connect without asking questions. For instance if you are on a trusted net where you do not need to worry about man-in-the-middle attacks.

    You can realise that wish with the following settings.

    Onetime setting as commandline argument:

    $ ssh -o UserKnownHostsFile=/dev/null \
     -o StrictHostKeyChecking=no user@192.168.0.100
    Warning: Permanently added '192.168.0.100' (RSA) to the list of known hosts.
    user@192.168.0.100's password:

    Permanent in ssh users config ~/.ssh/config

    StrictHostKeyChecking=no
    UserKnownHostsFile=/dev/null

    Explanation:

    UserKnownHostsFile sets the location of known hosts. In this case, we use /dev/null to make sure there aren’t any existing hosts with offending host keys already present.

    StrictHostKeyChecking=no means that ssh will automaticly add the key to the database (/dev/null) without asking for user confirmation.

    These 2 steps together mean that ssh will totally ignore any known or unknown host key and just login without silly questions.