| The term Port Forwarding is referred to the | | | | address here. Likewise, when another machine |
| technique of forwarding a network port from one | | | | outside the network is sending data to a recipient |
| particular machine to another machine. This | | | | inside the network, the data transmission will be |
| technique is usually applied when the receiving | | | | transmitted to the external IP address and not |
| machine is behind a network router. By doing this, | | | | directly to the intended recipient. The router will |
| it enables users from outside the LAN (local area | | | | then decide which recipient should receive the |
| network) to reach a private user in the LAN itself. | | | | data that is being transmitted. Fortunately, the |
| Now every machine on the internet has at least | | | | NAT in the router will take care of most of the |
| one IP address which is used to identify that | | | | re-directing except for those programs which |
| particular machine or device. Every IP address is | | | | NAT are not designed to work with. This is where |
| divided into many ports. The ports are there for | | | | port forwarding comes into place. This simple |
| the machines to communicate with each other, | | | | process is just a way for users to tell the router |
| for example (computer A is sending some data | | | | which machine in the local network is the intended |
| to computer B), and therefore forwarding the | | | | recipient and that the data should be directed to |
| port will also enhance the speed of the | | | | him. You will need to set up port forwarding rules |
| transmission between the two machines.Now let's | | | | for every port which you are using and any rules |
| take a look at how the machines are connected | | | | set up for a certain port will only work for that |
| to the internet when behind a router. The router | | | | certain port.One important factor to note is that a |
| is first connected to the internet which we will call | | | | port can only be used by a program at any one |
| it external IP. The router will then have its own | | | | time. For example, when computer A is using port |
| internal IP address. (every machine/device will | | | | 6000, it is using port 6000 on its internal IP |
| have at least one IP to identify them self). The | | | | address. If you have set up a port forwarding |
| router will then assign an individual IP address to | | | | rule for computer A and port 6000, the external |
| every machine that is connected to the router. | | | | IP address's port 6000 is also in use. This means |
| The router's IP address will then act as a | | | | that you can only use port 6000 on one |
| gateway for all the machines that are on it's | | | | computer on the network at a time. Using port |
| network. When a particular machine in the | | | | 6000 on two computers at the same time would |
| network wants to send data out to another | | | | violate the one program rule, and your data would |
| machine in the internet, it will first pass through | | | | get messed up.This generally sums up the term |
| the gateway before the router sends it out to | | | | Port Forwarding. Any comments can be directed |
| the recipient. The recipient however will not be | | | | to Lee is a VOIP consultant in VOIP singapore |
| able to tell who in the network is sending him the | | | | (Voip Singapore). |
| data as the internet will only show the external IP | | | | |