Changes

<code>sudo nano /etc/ssh/sshd_config

</code>

Inside the file, search for a directive called <code>PasswordAuthentication</code>. This may be commented out. Uncomment the line and set the value to "no". This will disable your ability to log in through SSH using account passwords:

<code>PasswordAuthentication no

</code>

Save and close the file when you are finished. To actually implement the changes we just made, you must restart the service.

<code>sudo service ssh restart

</code>

On CentOS/Fedora machines, the daemon is called <code>sshd</code>:

<code>sudo service sshd restart

</code>

After completing this step, you've successfully transitioned your SSH daemon to only respond to SSH keys.

[https://www.digitalocean.com/community/tutorials/ssh-essentials-working-with-ssh-servers-clients-and-keys More Information]