Gateway port forwarding

[C# Programming]

i try make a litle chat that will be server/client

but i have a major issu , when everithing is working local it seem i'm not able pass my gateway if i not forward manualy the required port.

now i have tryed the upnp and i think the code work but my netbox refuse the upnp protocole >>


so i feel not using upnp since not everyone able use it or they will have to enable it + i heard of lot of security issue.

now i searched an other way to do it and found nothing on net.
but i see msn is enable forward port in my non upnp box?? or even other app like azureus bit torrent accept in/out conection (they not forward the port in my netbox though).

so my question is how those programme able to do that on a non upnp gateway???
how can i do the same thing all i need is to echange 2 ligne of chat realy that can't be that hard >