CODEWITHSUNDEEP
githubrsaed25519
Alyssa
Alyssa

Reputation: 31

How can I get the RSA fingerprint for GitHub instead of their ED25519 key fingerprint?

I want to add GitHub to my computer's list of acceptable SSH hosts for a coding boot camp that I will be taking soon. The boot camp says that I need to do so via GitHub's RSA public key fingerprint. However, I keep getting GitHub's ED25519 public key fingerprint instead. Is there any way to fix this?

I used this code in GitBash:

ssh -T [email protected]

Each time I do, I receive this:

The authenticity of host 'github.com (140.82.113.3)' can't be established.
ED25519 key fingerprint is SHA256:+DiY3wvvV6TuJJhbpZisF/zLDA0zPMSvHdkr4UvCOqU.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])?

The boot camp I am taking a part of says not to accept unless I get the following public key fingerprint:

SHA256:nThbg6kXUpJWGl7E1IGOCspRomTxdCARLviKw6E5SY8

What should I do to get the RSA public key fingerprint above?

Upvotes: 3

Views: 8617

Answers (1)

bk2204
bk2204

Reputation: 76884

It used to be that GitHub offered only RSA and DSA keys as host keys. However, that changed recently, and GitHub now offers ECDSA and Ed25519 keys as well (and has removed the DSA key). On a fresh system, the latest versions of OpenSSH will prefer the Ed25519 key over the RSA key, which is normal and fine.

The GitHub API meta endpoint lists both the correct fingerprints and the actual SSH keys themselves. From a cursory glance, you appear to have the correct fingerprint, but you can verify that by pasting the fingerprint from the API at the prompt.

There is no reason to force the use of an RSA key here, but if you really want to do so, you can run ssh -oHostKeyAlgorithms=rsa-sha2-512,rsa-sha2-256 -T [email protected].

Upvotes: 4

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