There are times when you wish you could limit the internet bandwidth of a person on your network. Do you share internet with someone who always keeps his torrent client on, always streams videos online or just clogs up internet speed at exactly the moment when you are in need of it? If so, then this method might be useful to you.

SelfishNet is a software that helps you limit internet speed of computers on a network. It makes use of ARP Spoofing/poisoning in order to achieve this.

  • Disable your firewall. (Antivirus program may also block this.)
  • Now, execute the program : SelfishNetv0.2-beta.exe. Windows 7 users will need to run it as administrator (Right Click on it > Run as administrator).
  • While executing, if you receive a message box that says “problem registering the driver” or “problem installing the drivers”, then you need to install WinPcap (Alternate download link). It is required in order to capture packets travelling over a network. Once you have installed WinPcap and restarted your computer, reopen SelfishNetv0.2-beta.exe.

NIC Selection

  • Select your network adapter from the drop down list. I was connected to a wireless network via a USB adapter, so that’s what I selected from the list.
  • Click on the Network Discovery button at the top and all the computers/systems on the network will be listed there.

Start ARP Spoofing

  • You can either limit the download/upload speed or completely block the internet of a particular system. To limit download/upload speed, just set the limit under “Download/Upload Cap” and click on the flash button. If you want to block the internet completely, put a tick mark on the block check-box and click on the flash button.
  • To enable internet or remove download/upload limit, press the X button and close the program. Simply pressing the X button does not seem to work most of the time. So, close the program as well.

As mentioned before, I had used the software to block internet as well as limit internet speed of different systems on my Wireless Internet network and it had worked like a charm. There’s no guarantee that it will work on every computer, however.

SelfishNet is a free program developed by Clement Chazarra. 

How Does It Work?

A computer is able to determine the correct network device via something known as MAC address. Each networked device on a computer network, whether a printer, computer, router etc have their own unique MAC address.

Normal Traffic Pattern

On a normal network, each computer sends/receives internet data via a switch which is itself connected to a router. In this case, the computer takes note of the MAC address of the router so that it can locate the router and ensure that the data is received or sent from the correct place.

ARP Spoofed Network

What this program does is it spoofs the MAC address of your router. The system connects to router through the MAC address of router. But, if the MAC address of the router is copied by your computer, all the computers on the network will look for internet data in your computer, and will not be able to use internet. You, on the otherhand will be able to browse the internet in maximum speed.

Note that this is also one of the techniques used by hackers. When a MAC address is spoofed, other computers will send their data via your computer. Hence, you will be able to view the passwords or other data being sent. This is termed as Network sniffing. However, in this case, you are just spoofing the MAC address of your router in order to block others from using internet, which is not ‘sniffing’. Here, you will not be able to view their data .