D-Link DSL-500B User Manual page 47

Adsl router

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Web Configuration

Using port forwarding (the forwarding of requests to particular ports), the router is forced to send requests from

the Internet for a certain service, for example, a game, to the appropriate port(s) on the PC on which the game is

running. Port triggering is a special variant of port forwarding. Unlike port forwarding, the DSL router forwards the

data from the port block to the PC which has previously sent data to the Internet via a certain port (trigger port). This

means that approval for the data transfer is not tied to one specific PC in the network, but rather to the port numbers

of the required Internet service.

Where configuration is concerned, you must define a so-called trigger port for the application and also the protocol

(TCP or UDP) that this port uses. You then assign the public ports that are to be opened for the application to this

trigger port. The router checks all outgoing data for the port number and protocol. If it identifies a match of port and

protocol for a defined trigger port, then it opens the assigned public ports and notes the IP address of the PC that

sent the data. If data comes back from the Internet via one of these public ports, the router allows it to pass through

and directs it to the appropriate PC. A trigger event always comes from a PC within the local network. If a trigger

port is addressed from outside, the router simply ignores it.

Note:

An application that is configured for port triggering can only be run by one user in the local network at a time.

After public ports are opened, they can be used by unauthorized persons to gain access to a PC in the local

network.

When the DSL router is supplied, the NAT function is activated. For example, all IP addresses of PCs in the

local network are converted to the public IP address of the router when accessing the Internet. You can use

NAT settings to configure the DSL router to carry out the following tasks.

For functions described as follows, IP addresses of the PCs must remain unchanged. If the IP addresses of the

PCs are assigned via the DHCP server of the DSL router, you must disable DHCP server as the settings in the

local network menu entry for the lease time or assign static IP addresses for the PCs.

You can enable or disable the NAT function. By default, the NAT function is enabled.

D-Link DSL-500B User Manual

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