Chapter 10 Network Address Translation

The following table describes the labels in this screen.

Table 46 Network > NAT > General

LABEL

DESCRIPTION

NAT Setup

 

 

 

Enable Network

Network Address Translation (NAT) allows the translation of an Internet protocol address

Address

used within one network (for example a private IP address used in a local network) to a

Translation

different IP address known within another network (for example a public IP address used

 

on the Internet).

 

Select the check box to enable NAT.

 

 

Default Server Setup

 

 

Server IP

In addition to the servers for specified services, NAT supports a default server. A default

Address

server receives packets from ports that are not specified in the Application screen.

 

If you do not assign a Default Server IP address, the NBG-418N discards all packets

 

received for ports that are not specified in the Application screen or remote

 

management.

 

 

Apply

Click Apply to save your changes back to the NBG-418N.

 

 

Reset

Click Reset to begin configuring this screen afresh.

 

 

10.4 NAT Application Screen

Use the Application 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’s port forwarding settings, click Network > NAT > Application. The screen appears as shown.

Note: If you do not assign a Default Server IP address in the NAT > General screen, the NBG-418N discards all packets received for ports that are not specified in this screen or remote management.

Refer to Appendix E on page 209 for port numbers commonly used for particular services.

104

 

NBG-418N User’s Guide