DNS server security

[Tinu Patel]

I have a RH 7.1 box which is my DNS server.� I would like to secure it so that only 2 ports are open – SSH and DOMAIN.� I would also like to be able to send outbound mail only (not receive).� This is all the services that I need on that box.� What is the best way to approach this?� I am told that IP chains would do this for me, but don’t really know the syntax.� Could anyone please help me write my rules?   Thanks