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D-Link DSL-520B ADSL2+ Modem User Manual
Section 7 - Device Info
NAT - Virtual Server Setup
By default, DSL router blocks all external users from connecting to or communicating with your network. Therefore, the system
is safe from hackers whom 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 omputer 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.
Summary of Contents for DSL-520B
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