| So first, here are a couple of things that you can | | | | every computer has 65536 ports (numbered 0 to |
| do after you finish this section.- You can configure | | | | 65535). When a computer attempts to talk to |
| BitTorrent to give you excellent speeds- You can | | | | another computer, the attempt is always initiated |
| configure your computer to play multiplayer | | | | along with a port number.Forwarding Ports Lets |
| games over the internet- You can setup your | | | | assume that a computer on the Internet needs |
| computer as a terminal server (for remote | | | | to initiate a connection to a specific software on |
| desktop connections)- and many many more cool | | | | your computer. The software in discussion uses |
| stuff!!This tutorial consists of 2 sections1. | | | | port 12345. For simplicity, we will call the initiating |
| Understanding Port Forwarding2. Implementing | | | | computer as ClientX, and your computer as the |
| Port Forwarding on common routersWhat is | | | | ServerX. As we discussed earlier, clientX only |
| portforwarding?In one sentence, portforwarding | | | | sees (and knows) the external IP address i.e. the |
| makes the internet see your computer as if it | | | | IP address of your router. It tries to initiate a |
| were directly connected rather than being | | | | connection to that IP address with the port |
| connected though a router. For the same reason, | | | | number 12345. However, your router recieves |
| if you dont have a router, and your computer IS | | | | this request, and sees 4 computers in your house |
| directly connected to the Internet, then you wont | | | | connected to the router. The router is not able to |
| need this tutorial.A little explanation: When a | | | | figure which computer the connection from |
| computer is connected to the internet, it is | | | | ClientX was intended for! So it simply drops the |
| assigned a unique address called the IP address. | | | | connection.Port forwarding is a setting in the |
| This enables other computers on the internet to | | | | router which you can change to prevent this |
| communicate with it and send packets to it and | | | | from happening. By doing this, you can tell the |
| so on... An IP address has the format | | | | router that any connections for port 12345 has to |
| ###.###.###.###. It looks like four sets of | | | | be forwarded to ServerX. Now when the router |
| numbers, separated by a dot. Each set can have | | | | recieves a request for a connection on port |
| a value between 0 and 255.Usually the internet | | | | 12345, it checks its table and sees your entry |
| service provider is the guy who assigns you an IP | | | | saying that all connections for port12345 have to |
| address for your connection. However, he gives | | | | be forwarded to serverX. Hence it routes the |
| you only ONE ip address and this gets assigned to | | | | connection accordingly!Here we'll see how to do |
| the cable/dsl modem at your house. If you | | | | portforwarding on most routers. Scenario : Lets |
| directly connect your computer to the cable/dsl | | | | say you need to forward port 6889 to a |
| modem, you are using this IP address to | | | | computer whose Internal IP is 192.168.1.10.Step 1: |
| communicate with other computers on the | | | | Find your gateway IP address. To get this, in |
| internet. However, you can connect only one | | | | windows, select Start > Run. Type in "CMD" and |
| computer to the cable modem at any given time. | | | | hit enter. Inside the command window, type |
| So you go to the nearest store and buy a | | | | "ipconfig" and hit enter. The screen will show you |
| router.Role of the router A router connects to | | | | the default gateway. Note this down.Step 2: Open |
| the cable/dsl modem and splits the one internet | | | | Internet explorer. Enter your gateway from Step |
| connection into multiple connections so all the | | | | 1 in the address bar, and hit enter. A popup |
| computers in your house can enjoy internet | | | | window will ask you to authenticate into your |
| connectivity simultaneously. Once you get the | | | | router with a username and password. Enter the |
| router, you connect the router to your cable/dsl | | | | username and password. If you dont remember, |
| modem, and all your computers to the | | | | try the default ones below:Linksys router : Default |
| router.Internal and External IP addresses Once | | | | username "" password "admin" |
| you start using a router, the IP address given by | | | | NetGear router : Default username "admin" |
| your internet service provider gets assigned to | | | | password"password" |
| the router. This IP address is called the External IP | | | | Belkin router : Default username "" password"" |
| address, as it is part of the external network | | | | D-Link router : Default username "admin" |
| between your router and the Internet. The router | | | | password"" |
| in turn assigns new IP addresses to the | | | | Gateway router : Default username "admin" |
| computers connected to it. These addresses are | | | | password"admin" |
| a part of your Internal Network, and are called | | | | If you cant remember the password, post it on |
| Internal IP addresses. By set laws, an Internal IP | | | | the forum at and someone will help you!Step 3:For |
| address may start with the numbers 10,128, or | | | | Belkin routers, select virtual servers from the left |
| 192. All the other combinations are used for | | | | menu. Enter something for description. Type |
| external addressing.For example, my external IP | | | | "6889" or the required port number in both fields |
| address is 68.36.145.156. This IP address is | | | | for inbound port. Do the same for the Private |
| assigned to my router. I have two computers | | | | port fields too. Select the connection type from |
| connected to the router, and they have the IP | | | | the drop down. If you dont know what you need, |
| addresses 192.168.0.10 and 192.168.0.11. These are | | | | try UDP. If that doesnt work, come back and try |
| my internal addresses.The Port conceptEven | | | | TCP. In the private IP address field, enter the |
| when you use a router to connect many | | | | computer to which you need the connection |
| machines to the internet, other computers on the | | | | forwarded. In our case, this is 192.168.1.10Linksys |
| internet see one single machine with the external | | | | routers, select "Application and Gaming" from the |
| IP address of the router. They dont know that a | | | | top menu, and the select 'portrange forwarding' |
| router is sitting inside your house and splitting the | | | | from the submenu. In another family of linksys |
| external address into many internal IP addresses. | | | | routers, you can find 'Forwarding' section under |
| They can only make a connection to your router, | | | | 'advanced' tab of main setup page. Rest of the |
| and your router decides how to route the | | | | process is the same as that for Belkin routers |
| connection and to which internal computer to | | | | above.Netgear routers, you'll find 'Port Forwarding' |
| route it to.IP addresses are further divided into | | | | under the 'Advanced' table in the main page. The |
| channels called ports. This permits one IP address | | | | rest of the steps are same as above.Step 4:Save |
| to be shared by multiple programs at the same | | | | the setting and restart the router. Your port |
| time, each using a different port. By standard | | | | forwarding is complete. |