The most common reason that users want to get at their router’s administrative interface is to allow others to gain access to a PC on their internal network. Sometimes this is to engage in an online multi-player game, and in others to allow the world access to a configured web or FTP server. By default, all requests to your router from the outside world will be blocked unless you explicitly configure forwarding.
The Forwarding tab on a Linksys router allows you to selectively forward requests sent to a certain ports on your public IP address to another port and IP address on your internal network. The main Forwarding tab is great for customized forwarding needs (as with many games), but the UPnP (Universal Plug-and-Play) screen makes it easier to configure access to your own common server services like Web or FTP.
On neat feature recently introduced to many hardware routers is known as Port Triggering. Effectively, port triggering is a feature whereby your router can be configured to open a certain inbound port when an outbound request is made from your network to a specified port. For example, if you need a certain port opened for a game to function, you could specify a port trigger that tells the router to open an inbound port when it receives a request to connect to a certain outbound port. Then, the router will only open the inbound port when it has been triggered by the outbound program’s request.
