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Comment by justaj | Hacker News Reader

I'm always wary of using SSH services which aren't running on systems I control. If I'm not mistaken, an SSH service is able to see all of the pubkeys you have in your ~/.ssh/, so there goes your privacy.

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I believe you could use SSH config files to restrict which keys that each host would be able to see.

Something along the lines of:

    Host a.example
      IdentityFile ~/.ssh/id_a
      IdentitiesOnly yes

But they were public keys, it's completely fine if the entire world sees them

Perhaps the parent commenter is worried of public keys being used as a tracking vector?

Then they should create one key per service and only use that one.

Which they've done from the sound of it, and are concerned about the ability to read those other public keys and use them as a tracking vector.

As another commenter already pointed out, the IdentitiesOnly config option removes that ability. The ssh-config man page explains this.

Out of curiosity, are there reasons that that behavior shouldn't be the default?

I'm not sure it makes much sense unless you also override the default IdentifyFile.

Argh, IdentityFile.

I make the same damn mistake in my actual config file, too.

I can think of three reasons:

1. It would stop SSH agent forwarding from working if the remote has it enabled.

2. It would stop alternative SSH agent implementations from working.

3. It would only make sense if you actually have multiple identities.

I recently discovered github publishes any of your registered ssh public keys at https://github.com/username.keys

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