Observa Telecom TD851W User Manual page 54

4.3.2.4 Port Trigger
Choose "Advanced→NAT→Port Trigger", and then you can configure the port trigger rules in the
screen as shown in Figure 4-29.
Port trigger is used to restrict certain types of data packets from your local network to Internet.
Some applications require multiple connections, like Internet games, video conferencing, Internet
calling and so on. These applications cannot work with a pure NAT Router. Port Trigger is used for
some of these applications that can work with an NAT Router, which can be helpful in securing and
restricting your local network.
Nat Port rigger: Enable or disable the port trigger function on the device. After selecting,
click the Apply Changes button to save your configuration.
Application Type: You can select the service from the "Usual Application Name" and then
the following parameters, Match Port, Trigger Protocol, Relate Port and Open Protocol, will
be automatically filled. You can also define the application by yourself in the "User-defined
Application Name" field. But, you need to fill the following related parameters manually.
Start Match Port / End Match port: The start and end port to match.
TD851W 150Mbps Wireless N ADSL2+ Modem Router User Guide
Figure 4-29
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