DMZ is the easest and fastes way to get online with your MP game but has it's drawbacks. you may forget to pull the server from the DMZ after your done playing.
check out the guides section of my site, MOHadmin.com for a complete list of ports you will need to forward to get MOH running from behind a firewall / router.
or use this quick link:
http://www.mohadmin.com/nuke/modules.ph ... age&pid=13
Good luck