Figure 5-20: Port Triggering
Once configured, operation is as follows:
1. A local host makes an outgoing connection using a destination port number
defined in the Trigger Port field.
2. The router records this connection, opens the incoming port or ports associated
with this entry in the Port Triggering table, and associates them with the local host.
3. When necessary the external host will be able to connect to the local host using
one of the ports defined in the Incoming Ports field.
¾ Trigger Port - The port for outgoing traffic. An outgoing connection using this port
will "Trigger" this rule.
¾ Trigger Protocol - The protocol used for Trigger Ports, either TCP, UDP, or All (all
protocols supported by the router).
¾ Incoming Ports Range - The port or port range used by the remote system when it
responds to the outgoing request. A response using one of these ports will be
forwarded to the PC that triggered this rule. You can input at most 5 groups of ports
(or port section). Every group of ports must be apart with ",". For example,
2000-2038, 2050-2051, 2085, 3010-3030.
¾ Incoming Protocol - The protocol used for Incoming Ports Range, either TCP or
UDP, or ALL (all protocols supported by the router).
¾ Enable - The Enable checkbox enables port forwarding for the application.
¾ Common Applications - Some popular applications already list in the pull-down
list.
To add a new rule, enter the following data on the Port Triggering screen.
1. Enter a port number used by the application when it generates an outgoing
request.
2. Select the protocol used for Trigger Port from the pull-down list, either TCP, UDP,
or All.
3. Enter the range of port numbers used by the remote system when it responds to
the PC's request.
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