Creating multiple servers behind a router

#1 TNL does allow you to host multiple servers behind a firewall by using arranged connections. Basically what happens is this:

Server says to Master Server: "Hi I'm a server at this address (could be behind a firewall)"
Master Server says to server: "Ok cool, I will add you to the list."
Player joins and says to Master Server: "Give me all the servers!"
Master Server says to Player: "Ok here you go."
Player says to Master Server: "I want to join this server, but I can't ping it."
Master Server tells Server: "Start an arranged connection with this player."
Master Server tells Player: "I am arranging a connection between the two of you."

The Master Server then sets up a direct connection from the Player to the Server. The player can be behind a firewall, the server can be behind a firewall, both can be...it doesn't matter. It's a very powerful technique.

#2 Won't the firewall still block the inbound connection?

Firewalls/routers are pretty explicit devices, you have to specify what you are lettin thru. It's a feature. Unless I miss something in what you are saying Pat?

#3 I'm pretty sure a conneciton between two firewalled machines can be made if a third, non-firewalled machine deals with the handshaking and "plugs" the two connections together.

#4 You can instruct the firewalled server to make an outgoing connection to the player - if the player isn't behind a firewall.

Unless the idea is to make the master server a repeater for the connection, I have no idea how that could possibly work when both are behind firewalls.

#5 So this means that it's not supported by TGE, that I need to buy TNL and make it TGE compliant ? ^^
I read it was a non-sens doing that (hard work for small results). I guess I have to say goobye to have my game playable in cybercafes T.T