Wireless Home Networking - Index of

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Part IV: Using a Wireless Network
address. Similarly, when your router connects to the Internet, it’s assigned
its own public IP address: that is, its own identifying location on the Internet.
Traffic flowing to and from your house uses this public IP address to find its
way. After the traffic (which can be gaming data, an e-mail, a Web page, whatever)
gets to the router, the NAT function of the router figures out to which
PC (or other device) in the house to send that data.
One important feature of NAT is that it provides firewall functionality for your
network. NAT knows which computer to send data to on your network
because that computer has typically sent a request over the Internet for that
bit of data. For example, when a computer requests a Web page, your NAT
router knows which computer made the request so that when the Web page
is downloaded, it gets sent to the right PC. If no device on the network has
made a request — meaning that an unrequested bit of data shows up at your
public IP address — NAT doesn’t know where to send it. This process provides
a security firewall function for your network because it keeps this unrequested
data (which could be some sort of security risk) off your network.
NAT is a cool thing because it lets multiple computers share a single public IP
address and Internet connection and helps keep the bad guys off your network.
NAT can, however, cause problems with some applications that may require
this unrequested data to work properly. For example, if you have a Web server
on your network, you would rightly expect that people would try to download
and view Web pages without your PC sending them any kind of initial request.
After all, your Web server isn’t clairvoyant. (At least ours isn’t!)
Gaming can also rely on unrequested connections to work properly. For
example, you may want to host a game on your PC with your friends, which
means that their PCs will try to get through your router and connect directly
with your PC. Even if you’re not hosting the game, some games send chunks
of unrequested data to your computer as part of the game play. Other applications
that may do this include audio- and videoconferencing programs
(such as Windows Messenger) and remote control programs (such as
pcAnywhere).
To get these games (or other programs) to work properly over your wireless
home network and through your router, you need to get into your router’s
configuration program and punch some holes in your firewall by setting up
NAT port forwarding.
Of the many routers out there, they don’t all call this process port forwarding.
Read your manual. (Really, we mean it. Read the darn thing. We know it’s
boring, but it can be your friend.) Look for terms such as special applications
support or virtual servers.