Nat Advanced Screen - ZyXEL Communications NBG6515 User Manual

Table 57 Network > NAT > Application (continued)
L ABEL
#
Active
Name
Port
Server IP
Address
Modify
Apply
Reset
16.5 NAT Adva nc e d Sc re e n
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 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's WAN port
receives a response with a specific port number and protocol ("incoming" port), the NBG 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's trigger port settings, click
shown.
Note: Only one LAN computer can use a trigger port (range) at a time.
Chapter 16 Network Address Translation (NAT)
DESC RIPT IO N
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 numbers.
This field displays the inside IP address of the server.
Click the icon to display and modify an existing rule setting in the fields under
Edit
.
Applic a tio n Rule
Click the icon to delete a rule.
Re m o ve
Click to save your changes back to the NBG.
Apply
Click to begin configuring this screen afresh.
Re se t
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Add
. The screen appears as