T2 dedicated mode and router question

My friend and I have started playing t2 again. I'm hosting a server in ded mode on one comp. I know the master servers are down, how or what do I need to do to let him join via IP?

We've tried the modems IP ( ie 70.x.x.x ) and the routed down Ip ( 192.x.x.x) but he still times out.

What am I missing?

There are a number of ports you need to open up on the router and forward them to some local machine on your network. At least the port the game is bound to (prolly 28000 unless you changed something), and then some additional ones I cannot recall. BTW the 192.168.x.x is a private LAN address space.