Quote Originally Posted by scorp
The application I'm dealing with is Direct Connect (DC++)

This is how it works
there will be 4 computers behind * wireless/wired router and the router is connected to the internet. All 4 computers want to use DC++ sometimes even at the same time. How do I set it up so that it works without being in passive mode in DC++ or whatnot. Thanks.

How do I configure the router and how do I configure DC++ on each computer. (You can speak in general terms when it comes to the router since I don't know which router I'll be using yet, probably one of those netgear/dlink $40 things)
They can not all use that port at the same time, unless you know the IP addresses connecting to you (as was said earlier), and know how to set complex router rules.

WIth a program like DC++, you will NOT be able to do this, so either change the port each computer uses (and forward each port to a separate computer), or only use the program on one computer at a time, and forward it accordingly each time.