ZyXEL Communications G-2000 Plus - Manual (Page 149)

ZyAIR G-2000 Plus User’s Guide
Chapter 10 Single User Account (SUA) / Network Address Translation (NAT) 148
10.6 Trigger Port Forwarding
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 port in NAT to forward a
service (coming in from the server on the WAN) to the IP address of a computer on the client
side (LAN). The problem is that port forwarding only forwards a service to a single LAN IP
address. In order to use the same service on a different LAN computer, you have to manually
replace the LAN computer's IP address in the forwarding port with another LAN computer's IP
address,
Trigger port forwarding solves this problem by allowing computers on the LAN to
dynamically take turns using the service. The ZyAIR records the IP address of a LAN
computer that sends traffic to the WAN to request a service with a specific port number and
protocol (a "trigger" port). When the ZyAIR's WAN port receives a response with a specific
port number and protocol ("incoming" port), the ZyAIR forwards the traffic to the LAN IP
address of the computer that sent the request. After that computer’s connection for that service
closes, another computer on the LAN can use the service in the same manner. This way you do
not need to configure a new IP address each time you want a different LAN computer to use
the application.
10.6.1 Trigger Port Forwarding Example
The following is an example of trigger port forwarding.
Local End IP This is the end Inside Local IP Address (ILA). If your rule is for all local IP
addresses, then enter 0.0.0.0 as the Local Start IP address and
255.255.255.255 as the Local End IP address.
This field is N/A for One-to-One and Server mapping types.
Global Start IP This is the starting Inside Global IP Address (IGA). Enter 0.0.0.0 here if you have
a dynamic IP address from your ISP.
Global End IP This is the ending Inside Global IP Address (IGA). This field is N/A for One-to-
One, Many-to-One and Server mapping types.
Apply Click Apply to save your changes back to the ZyAIR.
Cancel Click Cancel to return to the previous screen and not save your changes.
Table 46 Address Mapping Edit
LABEL DESCRIPTION