Tell HN: GitHub changing host SSH keys

23 pointsrcarmo2 comments

I’m wary of this kind of thing, but since I just got a “host key verification failed” error when pushing some commits to GitHub I decided to check, and now that I’ve found the docs I’m issuing a PSA:

https://docs.github.com/en/authentication/keeping-your-accou...

mentions a key being sunset yesterday. Apparently that’s the one I was hung up on.

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I have configured SSH with `UpdateHostKeys yes` and got a message about the SSH key for github.com (ECDSA) and the respective IP address (RSA) mismatching.

I assume that GitHub did not serve traffic on the IP address in question for me in the last while, while it formerly did. So I only have the RSA key for the IP, but the new ECDSA (and the RSA) for the hostname - causing the mismatch.

I could fix this without removing any stored host keys from my known hosts by manually connecting to the IP address. This caused my SSH client to grab all the other host keys due to `UpdateHostKeys yes`. Afterwards connecting to github.com as usual worked like it should.

What was remediation for this like on your side?

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