IPTABLES - continued

After posting, I realized I should have elaborated more. I would like to have this FreeRadius box on the Internet so a few of my NAS devices can access it no matter where they are. I understand port 1812 and 1813 udp must be opened. I am looking for some example IPTABLES (fedora core) entries that would enable UDP access to FreeRadius. Thanks again, -Shaun