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# Fetching SSH hostkeys without interaction

---- dataentry snipplet ---- snipplet_tags: ssh, ssh-keys LastUpdate_dt: 2010-07-31 Contributors: Jan Schampera

Applies at least to `openssh`.

To get the hostkeys for a server, and write them to `known_hosts`-file (to avoid that yes/no query when the key isn't known), you can do:

    ssh-keyscan -t rsa foo foo.example.com 1.2.3.4 >> ~/.ssh/known_host

This example queries the hostkeys for the very same machine, but under 3 different \"names\" (hostname, FQDN, IP) and redirects the output to the `known_hosts`-file.

Notes:

- if done blindly, the `known_host`-file may grow very large. It might be wise to check for key existance first
- if multiple keys for the same host exist in `known_hosts`, the first one is taken (which might be an old or wrong one)

November 7, 2024
November 7, 2024

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