sshfs not mounting when using GPG auth key on YubiKey

[duncan-bayne]

Firstly, thanks for sshfs :)

If I ssh into my server, it works:

$ ssh dev.home
___________________________
< You have no real enemies. >
 ---------------------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||
~ $

If I try mounting my home directory via sshfs, it fails:

 $ sudo sshfs -v -o allow_other,default_permissions [email protected]:/home/duncan ~/dev/
[email protected]: Permission denied (publickey).

Pretty sure this has something to do with the fact that my SSH auth is happening via my GPG auth key, which lives on my YubiKey 5 Nano.

Versions of things:

• SSHFS version 3.7.1
• FUSE library version 3.10.5
• using FUSE kernel interface version 7.31
• fusermount3 version: 3.10.5
• YubiKey 5 Nano
• gpg (GnuPG) 2.2.27
• libgcrypt 1.9.4

I appreciate that I'll need to raise a PR to fix this myself, but wanted to raise the issue first.

[h4sh5]

What have you got in your ~/.ssh/config file?

Sometimes if you don't specifically define the SSH key via identityfile /path/to/key, it will try to authenticate using all keys on your system and then SSH will fail on too many attempts before it reaches your correct key (see https://superuser.com/questions/268776/how-do-i-configure-ssh-so-it-doesnt-try-all-the-identity-files-automatically)

Or, since you're using yubikeys you might have a agent socket setup that isn't defined in ssh config?

[duncan-bayne]

Currently I have:

SSH_AUTH_SOCK=/run/user/1000/gnupg/S.gpg-agent.ssh

... set in my environment variables. Should that do it?

[49016]

Not surprising that this doesn't work; sudo does not forward the SSH_AUTH_SOCK env var by default. Simply passing -E to keep the env works like a charm:

[lexi@ferris:~]$ sudo sshfs [email protected]:/tmp /tmp/mp
([email protected]) Password: 
read: Connection reset by peer

[lexi@ferris:~]$ sudo -E sshfs [email protected]:/tmp /tmp/mp

[lexi@ferris:~]$