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Chapter 3: Advanced Confi guration
40 Chapter 3
Fig. 30
Port Triggers Web Page (Fig. 30)
Some Internet activities, such as interactive gaming, require that a PC on the WAN side of your
gateway be able to originate connections during the game with your game playing PC on the
LAN side. You could use the Advanced...Forwarding page to construct a forwarding rule during
the game, and then remove it afterwards (to restore full protection to your LAN PC) to facilitate
this. Port Triggering is an elegant mechanism that does this work for you, each time you play the
game.
Port Triggering works as follows. Imagine you want to play a particular game with PCs somewhere
on the Internet. You make a one time effort to set up a Port Trigger for that game, by entering
into Trigger Range the range of destination ports your game will be sending to, and entering into
Target Range the range of destination ports the other player (on the WAN side) will be sending
to (ports your PC’s game receives on). Application programs like games publish this information
in user manuals. Later, each time you play the game, the gateway automatically creates the
forwarding rule necessary (see Advanced...Forwarding discussion above). This rule is valid until
10 minutes after it sees game activity stop. After 10 minutes, the rule becomes inactive until the
next matched outgoing traffi c arrives.
For example, suppose you specify Trigger Range from 6660 to 6670 and Target Range from 113
to 113. An outbound packet arrives at the gateway with your game-playing PC source IP address
192.168.0.10, destination port 6666 over TCP/IP. This destination port is within the Trigger Range,
so the gateway automatically creates a forwarding rule to forward any inbound packets destined
for port 113 to your game-playing PC at 192.168.0.10.
You can specify up to 10 port ranges on which to trigger.
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