User guide

Ubee Interactive 3.7 Gateway
DDW3612 Subscriber User Guide • July, 2010 35
3.7.13 Additional Information - Port Triggering
Some services use a dedicated range of ports on the client side and a dedicated
range of ports on the server side. With regular port forwarding you set a forwarding
rule to forward a service to the IP address of a LAN side host. The problem is that port
forwarding forwards a service to a single LAN IP address.
With port triggering, we define 2 kinds of ports: Trigger Port and Target Port. Trigger
port is defined as the service request with a specific destination port number sent from
a LAN side host. Target Port is defined as the ports this specific application requires a
LAN host to listen to. Thus, the server returns responses to these ports.
Example:
1. John requests a file from the Real Audio server (port 7070). Port 7070 is a “trigger”
port and causes the wireless router to record John’s computer IP address. The
DDW3612 Wireless Cable Modem Gateway associates John's computer IP
address with the "target" port range of 6970-7170.
2. The Real Audio server responds to a port number ranging between 6970-7170.
3. The DDW3612 Wireless Cable Modem Gateway forwards the traffic to John’s
computer IP address.
4. Only John can connect to the Real Audio server until the connection is closed or
times out.
End Port Enter a port number or the ending port number in a range of
port numbers.
Protocol Define the protocol type for this rule, UDP, TCP, or Both.
Enable Click to activate this rule.
Apply Click to save.