Generate hashed name for SSH known_hosts Is there an easy way to generate hashed hostnames to be added to the `~/.ssh/known_hosts` file? I'd like to add a `@cert-authority` line to the `~/.ssh/known_hosts` file. Obviously the `ssh-keygen` command would not get the CA cert. I think it also needs a connection to the server, and I'm not sure I can get it to hash a wildcard. So, how would I hash `"*.bar.com"`, for example, so that it can be used in the `~/.ssh/known_hosts` file? **Edit** : Having thought about it, hashed wildcards probably can't work, as it would be too difficult for the client to match a wildcard after it has been hashed. But, if I can still get a method to hash a domain without requiring a connection to the server (as `ssh-keygen` does), that would be great.

If you want to change the hostname for an _existing hashed host_ , edit your `known_hosts` file, replacing the hashed hostname with the plaintext hostname you wish associated with that key, and rehash the file:


ssh-keygen -H


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If you want to generate hashes for a list of hostnames without disturbing your `known_hosts`, create a file combining the hostnames you wish to hash with a valid key copied out of an existing `known_hosts` :


sample.bar.com ecdsa-sha2-nistp256 AAAAE2...
other.bar.com ecdsa-sha2-nistp256 AAAAE2...
diff.domain.org ecdsa-sha2-nistp256 AAAAE2...


Then hash this file using `ssh-keygen` :


ssh-keygen -f mytestfile -H