Configuring Port Triggering - Cisco Small Business RV220W Administration Manual

Configuring the Firewall

Configuring Port Triggering

Configuring Port Triggering
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Cisco RV220W Administration Guide
Port triggering allows devices on the LAN or DMZ to request one or more ports to
be forwarded to them. Port triggering waits for an outbound request from the LAN/
DMZ on one of the defined outgoing ports, and then opens an incoming port for
that specified type of traffic. Port triggering is a form of dynamic port forwarding
while an application is transmitting data over the opened outgoing or incoming
ports.
Port triggering opens an incoming port for a specific type of traffic on a defined
outgoing port.
Port triggering is more flexible than static port forwarding (available when
configuring firewall rules) because a rule does not have to reference a specific
LAN IP or IP range. Ports are also not left open when not in use, thereby providing
a level of security that port forwarding does not offer.
Port triggering is not appropriate for servers on the LAN, since there is a
dependency on the LAN device making an outgoing connection before incoming
ports are opened.
Some applications require that, when external devices connect to them, they
receive data on a specific port or range of ports in order to function properly. The
router must send all incoming data for that application only on the required port or
range of ports. The gateway has a list of common applications and games with
corresponding outbound and inbound ports to open. You can also specify a port
triggering rule by defining the type of traffic (TCP or UDP) and the range of
incoming and outgoing ports to open when enabled.
To add a port triggering rule:
Choose Firewall > Port Triggering.
Click Add.
Specify an easily-identifiable name for this rule.
Check the Enable box to enable the rule.
Select whether the port uses TCP or UDP protocol.
In the Outgoing (Trigger) Port Range section, specify the port number or range of
port numbers that will trigger this rule when a connection request from outgoing
traffic is made. If the outgoing connection uses only one port, then specify the
same port number in the Start Port and End Port fields.
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