Nat Advanced Screen - ZyXEL Communications NBG-419N User Manual

Chapter 15 Network Address Translation (NAT)
Table 59 Network > NAT > Application (continued)
LABEL
Port
Server IP Address
Application Rules Summary
#
Active
Name
Port
Server IP Address
Modify
Apply
Reset

15.5 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.
Trigger port forwarding solves this problem by allowing computers on the LAN to dynamically take
turns using the service. The NBG-419N 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 NBG-419N's WAN port receives a response with a specific port number and protocol ("incoming"
port), the NBG-419N 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 NBG-419N's trigger port settings, click Network > NAT > Advanced. The screen
appears as shown.
128
DESCRIPTION
Type a port number(s) to define the service to be forwarded to the specified
server.
To specify a range of ports, enter a hyphen (-) between the first port and the last
port, such as 10-20.
To specify two or more non-consecutive port numbers, separate them by a
comma without spaces, such as 123,567.
Type the IP address of the server on your LAN that receives packets from the
port(s) specified in the Port field.
This is the number of an individual port forwarding server entry.
This icon is turned on when the rule is enabled.
This field displays a name to identify this rule.
This field displays the port number(s).
This field displays the inside IP address of the server.
Click the Edit icon to display and modify an existing rule setting in the fields
under Add Application Rule.
Click the Remove icon to delete a rule.
Click Apply to save your changes back to the NBG-419N.
Click Reset to begin configuring this screen afresh.
NBG-419N User's Guide