My Friend the Firewall - The Other Reason Why NOT to use Peer Sharing Services (e.g. Limewire)

By Steve Puffenberger

You’ve no doubt heard of the music industry bringing suits against people for illegal downloads of music. This article isn’t about that, it’s about what else happens inside your computer when you use a peer sharing service like Limewire.

Al Gore’s analogy of the Information Superhighway is a very apt description of what happens on the Internet. Let’s say you were going on a trip to a friend in another city. You leave from a door of your house, depart from your driveway, take your local road to an artery that leads to the freeway. The freeway takes you to an exit far away, where you go down another artery, to another local street to your friend’s driveway and walk in their front door.

Well information packets do exactly the same thing as they pass through the Internet (and you can watch their progress using the Tracert command). The addresses on the street where you and your friend live are called IP addresses, for "Internet Protocol."

If you stand and look at your house, you’ll see there are doors, windows cracks, and maybe even a vent or mouse hole or two. On a computer each entry point is called a “port.” There are thousands of ports in a typical PC, but only a few are commonly used. For instance Port 80 is the one being used to display this Web page.

Your computer has a software “firewall” turned on (if it’s secure at all). The firewall closes all the ports, like locking all the doors and windows, only letting in data that has permission to enter. If you have a broadband router that distributes the Internet to several computers in your house, it also serves as a firewall, further blocking those ports. Peer sharing services OPEN ports. If a hacker finds that open port, he can jimmy the door (so to speak), break in and do damage when you’re not looking. These are termed “vulnerabilities.”

So what happens with peer file sharing services is like having tomatoes on your kitchen window sill. You don’t mind if people come in and take a tomato, because you have too many and you like to share. So  you leave the window unlocked, and your neighbor can come over anytime, slide open the kitchen window, take a tomato, and maybe leave a peach or an apple on the sill, close it and leave. Everyone’s happy and you’re sharing fruits and vegetables.

But that window is UNLOCKED!

So in the middle of the night, a stranger who finds out you’re sharing fruits and vegetables can slide the window open, crawl in, disable your security system, unlock all the doors and windows from the inside, invite all their friends over for a party and trash the place, stealing your wallet and bank accounts while they’re at it. And then they’ll find out who else you’re sharing tomatoes with and sneak into their windows and party there! When you wake up to find all these strangers have trashed your house, you pretty much have to strip it to the studs and start over.

That’s exactly what the vulnerability of an unlocked port that peer sharing programs bring. Hackers can get in, plant malware code that’s undetectable by antivirus programs and have a party in your computer. They’ll trash a machine so much that the only way out of it is the dreaded “flush and fill” where we reformat the drive and start over.

So the best way to avoid this is to never join a peer file sharing group in the first place. Not only will it keep you out of trouble with the copyright police, but it will save you lots of grief when the machine slows to a crawl and you realize you’ve become a zombie on a botnet.

If you have a peer sharing program installed, just uninstalling it will not fix the problem. The ports will remain open. To free yourself, you need to back up your user data, reformat the drive and reinstall everything. Or use the recovery disk or routine built into your computer. This is a service we offer through PainFree Tech Services™. If you need help, let us know!