Introduction

Port Forwarding

What is Port Forwarding?

Port Forwarding can also be known as Port Address Translation (PAT). PAT redirects a specified port to a different one.

This may be used, for example, to allow Remote Desktop Protocol (RDP) for more than one external computer. Under normal circumstances, RDP works on only port 3389 and as a result, only one computer can access a computer on the local network at a time. Using Port Forwarding on both the PAT device on the remote side and local side, it is possible to have multiple RDP connections.

Analogy

A Port Forwarding rule is similar to a set of instructions given to a guard (firewall) outside a building (network). When a parcel (data) is sent or received at the building, the guard will look at the parcel and see the name and address (port details). If the name and address match with his instructions, he will direct the parcel to a different door (port).

Port Forwarding Rule Details

Rule Name:

This is a friendly name so you can easily identify the Port Forwarding rule.

Direction:

Either set as Internet to PC (Inbound) or PC to Internet (Outbound). In the majority of scenarios, this should be set to Internet to PC.

Source Port:

This specifies which port the traffic is coming from.

Destination Port:

This specifies which port the traffic is being forwarded to.

From and To:

This specifies the source and destination IP addresses to route the traffic

Action:

The Action you wish to perform based on the details provided above.

Below is a description of how the Port Forwarding Actions affect traffic.

Allow:

This allows the specified traffic.

Deny:

Does not allow the specified traffic and will send a response to the other side, saying that the port is closed.

Reject:

Does not allow the specified traffic, and will not send any response back. Sometimes this is referred to as ‘Stealth’.