I believe a lot of us gone through the college life where we had to share Internet connection to cut down the expenditure in paying bills. Sharing the Internet is very easy as long as you have a router. I went through that many years ago when I was renting a room and shared the Internet with a few housemates. Most of them were an OK user because they only surf the web and play local computer games. But there’s one person, a college IT lecturer always leaves his computer turned on and download lots of stuff using LimeWire. That totally slows down my Internet connection and I find it very hard to access some websites. After telling him nicely not to do that or at least configure his P2P application not to download and upload so aggressively, he still hogs the Internet connection.

That time there was a Denial of Service for Windows XP which can reboot the computer or cause a blue screen of death by simply entering the IP address and clicking a button. I had to use that to make his computer unresponsive so that me and other housemates could use the Internet. Of course he didn’t knew about it and thought that it was his computer’s hardware problem. No doubt that it is unethical but sometimes we’re forced to do that when we’re faced with another person who is inconsiderate after telling him nicely not to do that. Don’t ask me for the XP nuker because it no longer works after XP SP1 and obviously doesn’t work with Vista and Windows 7. Recently I discovered another tool which can actually cut the connection of a computer in LAN.

I was watching a hacking video tutorial at milw0rm and found a tool called NetCut. It is a very old tool and most probably some of you might have heard about it. Basically NetCut is a tool that helps you admin your network by purely on ARP protocol. It can list IP-MAC table in seconds, turn on and off network on any computer on your LAN including any device like router and switch. Also, NetCut can protect user from ARP SPOOF attack.

I have a total of 3 computers at home and I turned them all on. Then I launched NetCut, within seconds it was able to find and list all 3 computers plus router in the program. I selected one of my computer running XP and click the “Cut Off” button. Amazingly the other computer that has been cut off couldn’t access any websites or even a shared folder on a computer in LAN. Tested on Vista and got the same results. I can’t even know what happened to the computer if someone was cutting me off using NetCut. I’d suspect that something was wrong with my network card since I couldn’t even access a shared folder in a LAN.

I am just merely sharing with you that there is something out there thats capable of disrupting your Internet connection without you knowing it. I am NOT encouraging you to go cutting off everyone’s line because you can be caught for using NetCut and probably lose friends or your job. The latest version of netCut is 2.0.8 and you cannot find the download link at the official website arcai.com. It is dangerous to download netCut from other sources because they might have been tampered with trojans or virus.

If you think you’ve been netcuted, I am going to show you how to protect your computer against NetCut on my next article.

[tags]netcut, security, arp, internet, network[/tags]