May NetBSD be with us, ok

but it is not a secret that people who use NetBSD as a gateway
often have Windows platform behind.

My problem is :

I have NetBSD as gateway, with ipnat (overloading my local network
to the great internet) and ipf

whatever ipf does, a NAT session is processed before
so a connection from inside the local network to internet
is not a problem, does everybody is agree till here ?

well, I am used to play Starcraft (now, now, it is time
to shoot me 'cause I use Dodows) throught battle.net
the connection by starcraft to battle.net server is NATed
so no problem, but while playing, each player try to connect
to other players (i.e an incoming connection for my gateway)

a got such thing with ipmon

***
Jan  4 02:39:24 <gateway_local_name> ipmon[11314]: 02:39:23.546609 2x
ppp0 @0:2 b 213.248.106.201,6112 -> <my_public_ip>,6112 PR udp len 20 9216  IN
***

after all, it is normal, because it is an incoming connection
so ipnat let it go, and ipf catch it

I would redirect such connection with ipnat "rdr"
but it is not really a good thing, and I do not know which
port while used (and it is udp, so it can change each time)

does anyone meet the same problem with Starcraft ?
is a socks server would be the solution ?

well, help !_
_-- 
Nicolas Bruno BASTIEN