I wrote a slightly less comprehensive guide of my own not that long ago, describing how to use Yubikey’s smartcard interface with OpenSSH (and no GPG): https://github.com/jamesog/yubikey-ssh
OMG thank you so much for this. I found it via google a couple of weeks ago and think I might actually be able to roll that out to the team. GPG-agent powered stuff, not so much.
Glad it’s of help to someone else :-)
OpenSSH 8.0 also supports ed25519 keys from a smartcard now so I might play with that and update the instructions.
I actually tried this this afternoon, but didn’t manage to make it work with a yubikey4…
The error message is different, but there’s still one! I didn’t take time to look into it, but if you managed to do it, I’d be happy to read it in your repository! Thank you very much for it btw!
I’ve used my way with a NEO and Yubikey 5. I don’t have a 4 so can’t test it unfortunately.
Happy to take a PR if you figure out what’s wrong with the 4. :-)