D-Link DSL-500B User Manual page 48

Web Configuration
NAT - Virtual Server Setup
By default, DSL router blocks all external users from connecting or communicating with your network. Therefore, the
system is safe from hackers who may try to intrude into the network and damage it.
However, you may want to expose your network to the Internet in limited and controlled ways in order to enable
some applications to work from the LAN (for example, game, voice, and chat applications) and to enable Internet
access to servers in the home network. The port forwarding feature supports both functions. This topic is also
referred as Local Servers.
The port forwarding page is used to define applications that require special handling by DSL router. All you need to
do is to select the application protocol and the local IP address of the computer that is using or providing the service.
If required, you may add new protocols in addition to the most common ones provided by DSL router.
For example, if you wanted to use a file transfer protocol (FTP) application on one of your PCs, you would simply
select FTP from the list and enter the local IP address or host name of the designated computer. All FTP-related
data arriving at DSL router from the Internet henceforth is forwarded to the specific computer.
Similarly, you can grant Internet users access to servers inside your home network, by identifying each service and
the PC that provide it. This is useful, for example, if you want to host a Web server inside your home network.
When an Internet user points his/her browser to DSL router external IP address, the gateway forwards the incoming
HTTP request to your Web server. With one external IP address (DSL router main IP address), different applications
can be assigned to your LAN computers, however each type of application is limited to use one computer.
For example, you can define that FTP uses address X to reach computer A and Telnet also uses address X to
reach computer A. But attempting to define FTP to use address X to reach both computer A and B fails. DSL router,
therefore, provides the ability to add additional public IP addresses to port forwarding rules, which you must obtain
from your ISP, and enter into the IP addresses pool. Then, you can define FTP to use address X to reach computer
A and address Y to reach computer B.
D-Link DSL-500B User Manual 48