Troubleshooting

Enable Debug Mode

Print verbose messages to /var/log/syslog to help in debugging issues.

0644 root root /etc/default/ssh

# Default settings for openssh-server. This file is sourced by /bin/sh from
# /etc/init.d/ssh.

# Options to pass to sshd
SSHD_OPTS=-ddd

Reload and restart SSHD.

systemctl daemon-reload
service ssh restart

Note

After a login attempt, the service may need to be restarted to test again.

Check /var/log/syslog for debug information.

Could not open authorized keys ‘{X}’: Permission denied

The keyfile could not be accessed. This generally happens when SSHD drops privileges to the user when logging in and the user cannot access the keyfile.

Directory containing keyfile is readable and executable by the user.
Keyfile is 0600.