We will begin by editing your SSH servers configuration
file: /etc/ssh/sshd_config
vi /etc/ssh/sshd_config
Confirm the following lines are set to yes (these are normally enabled by default and may be commented out):
RSAAuthentication yes
PubkeyAuthentication yes
***Make sure your SSH keys are working properly. If they are not you will be unable to log back in via SSH!***
Now change the below line to disable PasswordAuthentication and only allow access for ssh keys.
PasswordAuthentication yes
change this to:
PasswordAuthentication no
Now lets restart the SSH service
service sshd restart
Your SSH server should now be locked down to only allow access via SSH key authentication.
