How to SSH after deleting ~/.ssh folder

Chris

8/8/24, 6:49 PM

I was getting prompted to enter my password instead of authenticating with my SSH key. I thought if I deleted everything in ~/.ssh I would be able to generate a new key from my laptop, manually copy the public key, and use my SFTP client (Transmit) to add to authorized_keys on my server. Unfortunately, that did not work. I'm able to r+w in ~/.ssh, but I'm not able to edit /etc/ssh/sshd_config to enable PasswordAuthentication, through the SFTP client. I tried attaching the server (named "ubuntu") to a display that outputs:

Ubuntu 23.04 ubuntu ttyl ubuntu login:

It outputs incorrectly on everything I've tried. Is this something that can be fixed? Any suggestions would be greatly appreciated.

Link to: /var/log/auth.log https://drive.google.com/file/d/14adetEqSXUmM9-eh5ZSrvQvgP6n3ESYA

Here's the output of ➜ ssh -vvv -i id_rsa caleb@192.168.1.19 https://drive.google.com/file/d/1Ue1RS0_5JQl6_lnE65mpuscqxWfej16e

chrishall in ~/.ssh via ⬢ v19.8.1
➜ ssh -o "IdentitiesOnly=yes" -i id_ed25519 caleb@192.168.1.19
caleb@192.168.1.19: Permission denied (publickey).

chrishall in ~/.ssh via ⬢ v19.8.1
➜ ssh -o "IdentitiesOnly=yes" -i id_rsa caleb@192.168.1.19
caleb@192.168.1.19: Permission denied (publickey).

chrishall in ~/.ssh via ⬢ v19.8.1
➜ ssh -v id_ed25519 caleb@192.168.1.19
OpenSSH_9.0p1, LibreSSL 3.3.6
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: include /etc/ssh/ssh_config.d/* matched no files
debug1: /etc/ssh/ssh_config line 54: Applying options for *
debug1: Authenticator provider $SSH_SK_PROVIDER did not resolve; disabling
debug1: Connecting to id_ed25519 port 22.
ssh: Could not resolve hostname id_ed25519: nodename nor servname provided, or not known

chrishall in ~/.ssh via ⬢ v19.8.1
➜ ssh -v id_rsa caleb@192.168.1.19
OpenSSH_9.0p1, LibreSSL 3.3.6
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: include 
/etc/ssh/ssh_config.d/* matched no files
debug1: /etc/ssh/ssh_config line 54: Applying options for *
debug1: Authenticator provider $SSH_SK_PROVIDER did not resolve; disabling
debug1: Connecting to id_rsa port 22.
ssh: Could not resolve hostname id_rsa: nodename nor servname provided, or not known

0 + 9

server

ssh

steeldriver

8/8/24, 7:10 PM

If you can r+w in ~/.ssh, can't you just create a new ~/.ssh/authorized_keys file containing the new public key? why do you need to edit /etc/ssh/sshd_config?

Chris

8/8/24, 7:21 PM

I did but the server doesn't seem to recognize the change. Since I'm not able to use terminal, I'm not able to sudo systemctl restart ssh. I tried to restart the server at no result.

steeldriver

8/8/24, 7:31 PM

The new key should be recognized without restarting the server - the usual "gotcha" is overly permissive permissions on the file and/or ~/.ssh directory - at a minimum, they must not be writable by anyone other than the owner (I suggest 600 and 700 respectively)

Chris

8/8/24, 8:20 PM

Those are the permissions on both my local computer and server. I tried adding another key, but both are still being denied because of the /etc/ssh/sshd_config file on my server. I added a few commands above that might help.

waltinator

8/8/24, 11:53 PM

Read `man ssh`. It will explain the required permission for `~/.ssh/`, and will explain what you lost when you "deleted everything in `~/.ssh`". I think you've lost all `ssh`, `sftp` access to this system, for this userid. Can you connect a USB (or not) keyboard and mouse (along with your display). Use a powered USB Hub. Login, fix the permission on `~/.ssh/`, run `ssh-keygen`, and fix the errors. Read `man ssh-keygen`. For next time, read `man ssh-copy-id`. For completeness, read `man -k ssh`.

mpboden

8/9/24, 1:25 AM

Can you login to the server directly? If so, you should be able to edit `/etc/ssh/sshd_config` and set `PasswordAuthentication yes`. That way, you can at least login with a password. Are you appending your public key to `~/.ssh/authorized_keys` on server? Next, I think @steeldriver is correct about incorrect permissions. On server...`~/.ssh/` should be 700 & `~/.ssh/authorized_keys` should be 600. On local, `~/.ssh/` should be 700 & your private key should be 600. Next, ensure `~/.ssh/` & `~/.ssh/authorized_keys` on server are owned by user you're logging in with.

Chris

8/9/24, 4:08 PM

@mpboden When I connect a display, keyboard, and mouse to try and connect directly, the prompt says `Ubuntu 23.04 ubuntu ttyl ubuntu login:` and outputs `Login incorrect` for any username I enter. `~/.ssh/` is 700, `~/.ssh/authorized_keys` and private keys are 600, public keys are 644 on local and server owned by my username. Any idea why it's rejecting my username when I'm connected directly?

mpboden

8/9/24, 5:16 PM

I’d start here: [How do I reset a lost administrative password?](https://askubuntu.com/a/24024/1684306)

Chris

8/9/24, 5:35 PM

That gave me the idea to boot to recovery mode, enter root shell, and from there, I was able to edit the sshd_config file. Thanks for everyone's help!

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