Firewall & Port Forwarding

Your adsl modem by default should have its firewall enabled. If not turn it on!
The firewall will block all incoming ports except those that are used for the web. This means that we need to manually open the port, this is known as port forwarding.

Basics of Port Forwarding
Most routers come with a tool called a Virtual Server. What this allows us to do is:

to specify which ports we wish to open
select whether its TCP or UDP traffic (mostly TCP)
select the IP address of the computer that you wish to forward the traffic to also known as the "Host IP Address" or simply labeled "Local IP Address".

Every routers Virtual Server settings are at different places, try searching under Advanced Settings or NAT settings or under Firewall they can also be called "Reserved Mapping".

Before we can open a port we need the computer that we will be forwarding traffic to, to have a static IP address. Click here to visit the Static IP setup guide.

Once the static IP address has been setup we can go ahead and create the Port Forwarding setting. You should be aware of the port number you wish to open. Check the help information on the specific software.

These are the values that you will be asked for:

IP Addresses		Transport	External Port Range		Internal Port Range
Global	Internal	Type	Start	End	Start	End
		all

Global: This should be the IP address of the interface (the router should provide a default setting for this item.)
Internal: This is the IP address(computer) that you will be forwarding the traffic from that port to.
Port Range: If its a single port that you wish to open just fill in the same number for each item. If its a Port range fill in the Start and End.

Once added Save all the settings and then reboot the Router.

If this did not help and you need more Router specific help, login and Post the question on the ADSL Router Help forum .