Carrier Access Multi-Service Router (MSR) Card MSR/Adit 3K GUI - Manual (Page 173)

Adit 3000 (Rel. 1.6) and MSR Card (Rel 2.0) GUI 4-19
Security
Port Triggering
Port Triggering
Port triggering can be used for dynamic port forwarding. By setting port triggering rules, you can allow
inbound traffic to arrive at a specific LAN host, using ports different than those used for the outbound
traffic.
For example, you might access a gaming server on port 2222 using the TCP protocol. The gaming server
responds by connecting you using TCP on port 3333 to start the gaming session. In such a case, you
must use port forwarding since this scenario conflicts with the following default firewall settings:
The firewall blocks inbound traffic by default.
The server replies to the Adit’s IP, and the connection is not NATed back to your host.
In order to solve this, you need to define a Port Triggering entry that allows inbound TCP traffic on port
3333 only after a LAN host generates TCP traffic to port 2222. This results in accepting the inbound
traffic from the gaming server and sending it back to the LAN Host that originated the outgoing traffic
on port 2222.