Chapter 11 Network Address Translation (NAT)
VMG8825-B Series User’s Guide
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Figure 87
Applications: Add
The following table describes the labels in this screen.
11.4 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 VMG 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 VMG's WAN port
receives a response with a specific port number and protocol ("open" port), the VMG 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.
Table 60 Applications: Add
LABEL
DESCRIPTION
WAN Interface
Select the WAN interface that you want to apply this NAT rule to.
Server IP
Address
Enter the inside IP address of the application here.
Application
Category
Select the category of the application from the drop-down list box.
Application
Forwarded
Select a service from the drop-down list box and the VMG automatically configures the
protocol, start, end, and map port number that define the service.
View Rule
Click this to display the configuration of the service that you have chosen in
Application
Fowarded
.
OK
Click
OK
to save your changes.
Cancel
Click
Cancel
to exit this screen without saving.