How to force SSH key only access to your Linux system with password access being denied.

Creating SSH key access to Linux instead of a password.

Open the sshd config file for editing:

nano /etc/ssh/sshd_config

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

#PasswordAuthentication no

Make sure it is:

PasswordAuthentication no

Press 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.