Some routers have a Virtual DMZ feature that make this easy. On my 2Wire Home GW I just tell it what internal IP address to use for the Virtual DMZ and it handle the rest. Linksys has something similar
"Ron Rico, Boss. You can call me Captain Ron..."
The Naked Fatty!
Southern Q Limo Elite Gravity Fed/FEC-100/Memphis Pro SS/PBC/LBGE X 2/SBGE/Mini BGE/Nomad Pellet-matic/Good-One Model 42/WSM X 2/Cookshack Smokette 008/Weber Performer/Saber Cast 500/Weber Kettle X 2/Weber Smokey Joe/WGA/UDS/Coffee Roasting Gasser