|Your setup looks good.|
It's common practice (and and just plain smart) to have a firewall between the external network and your internal network.
Chances are you will need to do a "port forward" on your firewall to allow incoming traffic through to your server. Since your server is running CentOS I suspect you're going to connect via SSH. So, your port forward would look as follows:
forward Port 22 (ssh) to [LAN IP of server]
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.