[CentOS] Signing In Other than Root

[John Doe]

From: Susan Day <suzieprogrammer at gmail.com>
>How do I make it so that it's impossible to SSH into the server directly as root? That is, make it necessary to SSH in as an ordinary user and then su to root?

Google says:

  /etc/ssh/sshd_config:
    PermitRootLogin no

JD