SSH without password does not work after upgrading from 18.04 to 22.04

SSH without password does not work after upgrading from Ubuntu 18.04 to Ubuntu 22.04. The client is Ubuntu 22.04 and the server is Ubuntu 14.04. Using Ubuntu 18.04 as client works correctly.

I have done the correct steps of generating the key in .ssh and copying it to the server, but in Ubuntu 22.04 it does not work

Summary of the steps I have always performed and have always worked:

ssh-keygen -t rsa
cat .ssh/id_rsa.pub | ssh -p 1331 user@server 'cat >> .ssh/authorized_keys'

Is this a Seahorse problem? In Seahorse in Ubuntu 22.04 I can't find the option "The owner of this key is authorized to connect to this computer" that if it is in 18.04. I don't know if this may have something to do with it

Has this happened to anyone else?

4 Answers

The RSA SHA-1 hash algorithm is being quickly deprecated. There is a workaround for re-enabling RSA at SSH-RSA key rejected with message "no mutual signature algorithm" .

Add the following line to /etc/ssh/ssh_config on the client side:

PubkeyAcceptedKeyTypes +ssh-rsa

You can add the following line to /etc/ssh/ssh_config if you want the add this config for all users or to ~/.ssh/config if you want to add this to your own user.

HostKeyAlgorithms +ssh-rsa

Also you can use the PubkeyAcceptedKeyTypes SSH option:

ssh -o PubkeyAcceptedKeyTypes=+ssh-rsa foo@old_server

Do this:

$ eval `ssh-agent -s`
$ ssh-add ~/.ssh/(your key filename)

Then test:

$ ssh -T 

It has been OK.