this post was submitted on 14 Aug 2024
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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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[–] kolorafa 1 points 3 months ago

The only reason ssh client would "hang" without any output is when it's waiting for external key storage to allow access. It's designed that way to give user some time to approve access to key storage.

It sometimes happen that the installed key storage is broken in a way that it fails to show user modal, for any reason (showing on wrong screen, wrong desktop, wrong activity, wrong framebuffer, ....)

One solution (that you already did) is to change the SSH agent env variable to point to different key storage.

Another would be (if possible) to uninstall the broken key storage if you don't use it. But it is sometimes needed/used by other apps.

It's overall good to notify/open bug on your distro issue tracker to notify that some packages are missconfigured (maybe have missing dependencies) or conflicts with other ones.

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

What happens if you run commands on that blinking cursor? E.g. it you run ls do you get an output? I've had that happen in the past, don't remember the reason though.

[–] [email protected] 1 points 3 months ago

also no output

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

I am not sure I "solved" this but when I add this to my startup script for my terminal (~/.zshrc):

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

it works then. I am not sure I'm still using the ssh agent, but at least it also does not cache my passphrase (or private key in ram)

[–] [email protected] 1 points 4 months ago (3 children)

what are your ssh config settings: ~/.ssh/config or /etc/ssh/ssh_config

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[–] [email protected] 0 points 4 months ago (1 children)

@dysprosium ssh agent manages your ssh keys and automatically passes them as an identity when connecting to a server

If you want to connect without it, you can simply pass -i \<path to private key\> flag

[–] [email protected] 1 points 4 months ago* (last edited 4 months ago) (1 children)

okay I tried that, using -i to specify private key. I get the same thing: blank / blinking cursor. When I use verbose -v flag, I see that in BOTH cases (I see about 50 lines) it ends with these two lines:

debug1: Offering public key: /home/username/.ssh/id_rsa RSA SHA256:j3MUkYzhTrjC6PHkIbre3O(etc) agent
debug1: Server accepts key: /home/username/.ssh/id_rsa RSA SHA256:j3MUkYzhTrjC6PHkIbre3OT(etc) agent

where (etc) is some redacted text. It seems the server is ACCEPTING the key, which is nice. But then it’s still a blinking cursor…

[–] [email protected] 0 points 4 months ago* (last edited 4 months ago) (1 children)

@dysprosium Mind trying with -vvvv flag and sharing the output instead of -v?

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[–] mvirts 0 points 3 months ago

Your shell for user pi may be broken. Try adding the shell command to your ssh command explicitly like

ssh pi@host /bin/sh

Or use /bin/bash

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