How to force SSH key only access to your Linux system with password access being denied.
Open the sshd config file for editing:
Find and set/ensure the following have these values:
PasswordAuthentication no PubkeyAuthentication yes UsePAM no ChallengeResponseAuthentication no
Note Being commented out has no effect, it must be stated
Make sure it is:
control + x then
y and then
enter to save.
Now restart the sshd service with:
service ssh restart
It is always best to check before you close the session that the sshd service accepts your key file, do this by opening up a new ssh session connecting with your private key file.