User Manual

Chapter 10 Network Address Translation
NBG-418N v2 User’s Guide
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The following table describes the labels in this screen.
10.4 NAT Applic a tion Sc re e n
Use the Applic a tion screen to forward incoming service requests to the server(s) on your local network.
You may enter a single port number or a range of port numbers to be forwarded, and the local IP
address of the desired server. The port number identifies a service; for example, web service is on port 80
and FTP on port 21. In some cases, such as for unknown services or where one server can support more
than one service (for example both FTP and web service), it might be better to specify a range of port
numbers.
In addition to the servers for specified services, NAT supports a default server. A service request that does
not have a server explicitly designated for it is forwarded to the default server. If the default is not
defined, the service request is simply discarded.
Note: Many residential broadband ISP accounts do not allow you to run any server processes
(such as a Web or FTP server) from your location. Your ISP may periodically check for
servers and may suspend your account if it discovers any active services at your
location. If you are unsure, refer to your ISP.
Port forwarding allows you to define the local servers to which the incoming services will be forwarded.
To change your NBG-418N v2’s port forwarding settings, click Ne twork > NAT > Applic a tion. The screen
appears as shown.
Note: If you do not assign a De fa ult Se rve r IP a ddre ss in the NAT > Ge ne ra l screen, the NBG-
418N v2 discards all packets received for ports that are not specified in this screen or
remote management.
Refer to
Appendix F on page 218 for port numbers commonly used for particular services.
Table 48 Network > NAT > General
LABEL DESCRIPTION
NAT Setup
Network Address
Translation
Network Address Translation (NAT) allows the translation of an Internet protocol address used
within one network (for example a private IP address used in a local network) to a different IP
address known within another network (for example a public IP address used on the Internet).
This field displays whether the NAT is enabled or disabled.
Default Server Setup
Enable Click the Ena ble check box to activate the default server.
Server IP
Address
In addition to the servers for specified services, NAT supports a default server. A default server
receives packets from ports that are not specified in the Applic a tion screen.
If you do not assign a default server IP address, the NBG-418N v2 discards all packets received
for ports that are not specified in the Applic a tion screen or remote management.
Apply Click Apply to save your changes back to the NBG-418N v2.
Reset Click Re se t to begin configuring this screen afresh.