I work for a company where the bosses are big into the Call of Duty
game. We currently play in house at lunch time but he is wanting for one
of our architects to be able to join in our Call of Duty playing at lunch
time only. How can this be done and not compromise our servers security
to much?

The Call of duty ports are as follows per www.tmmworld.com:
CD Valdiation Key UDP port 20500
Master Server and Monitoring UDP 20510
Call of Duty Master UDP port UDP 28960

Just wondering,