ZyXEL Communications NBG6503 User Manual
Chapter 14 Network Address Translation (NAT)
NBG6503 User’s Guide
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14.5 NAT Advanced 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.
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 Router 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
Router's WAN port receives a response with a specific port number and protocol ("incoming" port),
the Router 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.
turns using the service. The Router 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
Router's WAN port receives a response with a specific port number and protocol ("incoming" port),
the Router 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.
To change your Router’s trigger port settings, click Network > NAT > Advanced. The screen
appears as shown.
appears as shown.
Application Rules Summary
#
This is the number of an individual port forwarding server entry.
Active
This icon is turned on when the rule is enabled.
Name
This field displays a name to identify this rule.
Port
This field displays the port number(s).
Server IP
Address
Address
This field displays the inside IP address of the server.
Modify
Click the Edit icon to display and modify an existing rule setting in the fields under Add
Application Rule.
Application Rule.
Click the Remove icon to delete a rule.
Apply
Click Apply to save your changes back to the Router.
Reset
Click Reset to begin configuring this screen afresh.
Table 51 Network > NAT > Application (continued)
LABEL
DESCRIPTION