ZyXEL Communications NBG-417N User Manual
Chapter 11 Network Address Translation (NAT)
NBG-417N User’s Guide
118
11.5.1 Trigger Port Forwarding Example
The following is an example of trigger port forwarding.
Figure 73
Trigger Port Forwarding Process: Example
1
Jane requests a file from the Real Audio server (port 7070).
2
Port 7070 is a “trigger” port and causes the NBG-417N to record Jane’s computer IP address. The
NBG-417N associates Jane's computer IP address with the "incoming" port range of 6970-7170.
NBG-417N associates Jane's computer IP address with the "incoming" port range of 6970-7170.
3
The Real Audio server responds using a port number ranging between 6970-7170.
4
The NBG-417N forwards the traffic to Jane’s computer IP address.
5
Only Jane can connect to the Real Audio server until the connection is closed or times out. The
NBG-417N times out in three minutes with UDP (User Datagram Protocol), or two hours with TCP/IP
(Transfer Control Protocol/Internet Protocol).
NBG-417N times out in three minutes with UDP (User Datagram Protocol), or two hours with TCP/IP
(Transfer Control Protocol/Internet Protocol).
11.5.2 Two Points To Remember About Trigger Ports
1
Trigger events only happen on data that is going coming from inside the NBG-417N and going to
the outside.
the outside.
End Port
Type a port number or the ending port number in a range of port numbers.
Trigger
The trigger port is a port (or a range of ports) that causes (or triggers) the NBG-
417N to record the IP address of the LAN computer that sent the traffic to a
server on the WAN.
417N to record the IP address of the LAN computer that sent the traffic to a
server on the WAN.
Start Port
Type a port number or the starting port number in a range of port numbers.
End Port
Type a port number or the ending port number in a range of port numbers.
Apply
Click Apply to save your changes back to the NBG-417N.
Reset
Click Reset to begin configuring this screen afresh.
Table 48
Network > NAT > Advanced
LABEL
DESCRIPTION