off2
when you try and host a game, be sure you deselect the box that says "show my game in cfs server list", or someting close to that.
once you do this, you will not be promted for a username and password.
If you have a game hosted and up and running, hit ctl -h and it will give you your ip address.....go back to the off2 forum, and post the fact you have a mp game up, and post your ip.
If you plan to do multiplayer missions, suggets you read pds tuturial in the sticky section of the off2 forum.
like ovs said, most people have switched over to off3, but there are stlll people playing off2.
good luck
duck