I upgraded my remote server to Ubuntu 16.04 (from 14.10).
Then I reconfigured it to only use keys and not passwords.
Did that by editing the /etc/ssh/sshd_config
file where I changed to the following:
PasswordAuthentication no
PubkeyAuthentication yes
ChallengeResponseAuthentication no
Then reloaded the shh service with: systemctl reload sshd
The issue at hand is that all public ssh-keys in the ~/.ssh/authorized_keys file seems to be invalid for some reason.
So now, I can not log in anymore. I only get Permission denied (publickey). I tried numerous -o options to force a password prompt with no success. All I need is to be able to log in using a password.
All help is highly appreciated.