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why can't I connect to my ssh server UNLESS I enter eval "$(ssh-agent -s)" first? (lemmy.dbzer0.com)

submitted 4 months ago* (last edited 3 months ago) by [email protected] to c/[email protected]

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I have my own ssh server (on raspberry pi 5, Ubuntu Server 23) but when I try to connect from my PC using key authentication (having password disabled), I get a blank screen. A blinking cursor.

However, once I enter the command eval "$(ssh-agent -s)" and try ssh again, I successfully login after entering my passphrase. I don't want to issue this command every time. Is that possible?

This does not occur when I have password enabled on the ssh server. Also, ideally, I want to enter my passphrase EVERYTIME I connect to my server, so ideally I don't want it to be stored in cache or something. I want the passphrase to be a lil' password so that other people can't accidentally connect to my server when they use my PC.

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[–] gedhrel 1 points 3 months ago (1 children)

Okay, that agent process is running but it looks wedged: multiple connections to the socket seem to be opened, probably your other attempts to use ssh.

The ssh-add output looks like it's responding a bit, however.

I'd use your package manager to work out what owns it and go looking for open bugs in the tool.

(Getting a trace of that process itself would be handy, while you're trying again. There may be a clue in its behaviour.)

The server reaponse seems like the handshake process is close to completing. It's not immediately clear what's up there I'm afraid.

[–] gedhrel 1 points 3 months ago (1 children)

Is this problem a recurring one after a reboot?

If it is it warrants more effort.

If not and you're happy with rhe lack of closure, you can potentially fix this: kill the old agent (watch out to see if it respawns; if it does and that works, fine). If it doesn't, you can (a) remove the socket file (b) launch ssh-agent with the righr flag (-a $SSH_AGENT_SOCK iirc) to listen at the same place, then future terminal sessions that inherit the env var will still look in the right place. Unsatisfactory but it'll get you going again.

[–] [email protected] 1 points 3 months ago* (last edited 3 months ago) (1 children)

reboot makes no difference. A new terminal gives the symptoms from the start.

I think I found a bad workaround. If I add this script to ~/.zshrc (because I'm not using bash but zsh)

SSH_AUTH_SOCK=/tmp/ssh-agent-$USER-socket
export SSH_AUTH_SOCK
if [ ! -S "$SSH_AUTH_SOCK" ]; then
    eval $(ssh-agent -a "$SSH_AUTH_SOCK")
fi

then it works. But I think I'm still using the ssh agent which I actually should not be using. At least it's asking for the passphrase every time, which is nice. Even in the same terminal after ssh logout.

EDIT: The first two lines do the trick as well:

SSH_AUTH_SOCK=/tmp/ssh-agent-$USER-socket
export SSH_AUTH_SOCK

EDIT: If I change this SSH_AUTH_SOCK to ANYTHING else, it also works. So /run/user/1000/gcr/ssh does not work. I gave ample permission to this file, so that cannot be the problem. Perhaps BECAUSE this is a file. I think the SSH_AUTH_SOCK should point to a nonexisting file because then it makes temporarily a special file that it needs. Ok I'm just shooting in the dark.

[–] gedhrel 1 points 3 months ago (1 children)

Minimise your windows one at a time and check that the gnome keyring hasn't popped up a dialog box sonewhere behind everything else that's asking you if it's okay to proceed.

[–] [email protected] 1 points 3 months ago (1 children)

No unfortunately not... Would've been a real pain.

[–] mvirts 1 points 3 months ago

Have you considered storing your keys unencrypted? In this case ssh doesn't need the agent or a password.

Yes it's not as secure, but for me it's good enough considering my systems at home are not doing anything important. If you have an encrypted home partition it's just as secure when your partition is unmounted.