Using Port Triggering - NETGEAR CG814WG Reference Manual

Reference Manual for the Model CG814WG Wireless Cable Modem Gateway

Using Port Triggering

Port Triggering is an advanced feature that allows you to dynamically open inbound ports based on
outbound traffic on different ports. This is an advanced feature that can be used for gaming and
other internet applications.
Port Forwarding can typically be used to enable similar functionality, but it is static and has some
limitations. Ports will be open to traffic from the internet until the port forwarding rule is removed.
Additionally, port forwarding does not work well for some applications when your WAN IP
address is assigned by DHCP, and is changed frequently. Port Triggering opens in incoming port
temporarily and can does not require the server on the internet to track your IP address if it is
changed.
Port Triggering monitors outbound traffic. When the gateway detects traffic on the specified
outbound port, it remembers the IP address of the computer that sent the data and "triggers" the
incoming port. Incoming traffic on the triggered port is then forwarded to the triggering computer.
An example of Port Triggering for Internet Relay Chat (IRC) is shown in
connect to an IRC server, the server tries to connect back on port 113 to do an Ident lookup. Unless
you have configured Port Forwarding to open port 113, the traffic will be blocked. In this example,
the initial login to the server in the range of ports 6660 to 6670 will be detected. This will trigger
5-10
Figure 5-7. When you
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