The Port Triggering Screen - ZyXEL Communications P-660HN-51 - V1.10 Manual

The following table describes the labels in this screen.
Table 30 Applications: Add
LABEL
WAN Interface
Server IP
Address
Application
Category
Application
Forwarded
View Rule
Apply
Cancel

8.4 The Port Triggering Screen

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 ZyXEL Device 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 ZyXEL Device's
WAN port receives a response with a specific port number and protocol ("open"
port), the ZyXEL Device 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.
P-660HN-51 User's Guide
DESCRIPTION
Select the WAN interface that you want to apply this NAT rule to.
Enter the inside IP address of the application here.
Select the category of the application from the drop-down list box.
Select a service from the drop-down list box and the ZyXEL Device
automatically configures the protocol, start, end, and map port number
that define the service.
Click this to display the configuration of the service that you have chosen
in Application Fowarded.
Click Apply to save your changes.
Click Cancel to exit this screen without saving.
Chapter 8 Network Address Translation (NAT)
139