I've been waiting for someone to ask about Limewire and Kazaa and other P2P file sharing tools out there. I'm surprised it has taken this long. Since I'm guessing that most of adults here aren't using these P2P file sharing tools, when you find it on your computers, it is a case of your kids generation-gapping you.

For those who have kids, a high speed Internet connection (esp. DSL or something else that is "always on"), a computer with lots of storage and one or more kids with a MP3 player, here's the deal on P2P tools and networks:

Many kids are using these P2P file sharing networks to download music "for free." The "for free" part presents a legal issue for you, the owner of the computer and the person paying for the ISP bill. I'll get to that later.

Some of you will say "This isn't new -- hasn't this been around since Napster?"

Yes... but Limewire (and other P2P applications) were written in response to the courts shutting down a central server like Napster. With Limewire, there is no "central server" -- the content is spread all over the world. 

These P2P file sharing apps, like Limewire, are often based on what is called the "gnutella" infrastructure. Limewire is a "client" of the "gnutella" architecture.

These file sharing networks based on gnutella are "collaborative" file sharing networks. There is no central file server -- there is a distributed directory service and the files are flung across every computer that has downloaded them in the past, and every computer that has put out files for uploading by other people.

With Limewire, your computer and ISP connection becomes a candidate server. The same deal applies to all users of Limewire -- they can become candidate servers for the files they've downloaded, to "distribute" the load.

Oh, what's that? Your ISP will ding you if you try to run a web site on your computer? Heh. Guess what? You're not running a web site, you're running something much worse than a web site as far as the ISP is concerned. If this violates your ISP rules, your ISP might warn you once, then shut down your connection if the problem persists. ISP's hate Limewire is a flaming passion. It results in heavy loads as kids are sharing music, movies, porn, you name it -- all over the networks in ways that break the ISP's modeling of usage and network performance.

Now enters the legal issue: It is one thing for you or your kids to download copyrighted material - it is a whole 'nother class of liability to provide it for other people to download. The music and film industry have been rather outlandish in how they're going after some people for this, but it is their copyrighted material, and they do have the law on their side in this. The ISP's are often the first people to receive a "cease and desist" letter from the MPAA and RIAA, and this is why the ISP's block these file-swapping applications and put in the legal language into your ISP service agreement. The ISP is trying to cover their butts, because they don't want to be first in the lawsuit filed when the MPAA/RIAA comes after users of their network.

Can Limewire be blocked? Yes, until someone decides they're going to set up a proxy on your computer, and "wrap" the limewire traffic in the HTTP protocol, and send it to one of the many reverse proxies on the 'net that unwrap the limewire traffic from HTTP and re-connect the user to the limewire network. gnutella was designed to thwart attempts to block it. These little rip-off artists think that this is a "free speech" issue, where the very idea of copyrights seems to bother the little twerps.

This P2P file sharing issue is a BIG deal in schools, libraries and companies. If you have an industrial strength firewall product (like the PIX from cisco), these boxes have features to shut down these P2P file sharing networks for once and for all with a couple of configuration lines. Your PC doesn't, not even with the Windows XP firewall, because the ports can be changed, the URL's change, the target IP addresses change. Once the limewire user starts running proxies on your computer, the port blocking is thwarted. Industrial strength firewalls are looking at data patterns and patterns of IP port behavior to implement the blockage.

Due to the distributed nature of limewire and gnutella, locking individual web sites, individual IP addresses, etc, is about as effective as trying to step on one ant when you have an ant infestation. You know another one will appear unless you kill them at the nest. Since such various killjoys as The Law, Judges, Cops and Prosecutors seem to get their shorts in a bunch and frown on the idea of "killing them at the nest" where idiotic humans are involved, we can't do that. We know that blocking IP addresses and web sites won't work. Your only first option is to go after the ports and prevent the use of proxies.

The "TerminatorX" software appears to have some history to it and appears to block just about everything that would give a parent indigestion from their kids' use of a computer. I have never used this software, seeing as how we don't have this gnutella/limewire issue here.

TerminatorX costs money, but as I said earlier, to nail the door shut on these file sharing networks isn't so easy. These file sharing programs are being written to deliberately get around ISP's blocking ports, etc. These want their "free music sharing" regardless of the law or ISP's service agreements and efforts to enforce them.

Then there are the security issues that arise from someone running gnutella/Limewire on your computer with an "always on" connection:

http://www.unwantedlinks.com/Guntella-alert.htm

Personally, if the source of the problem is an employee or child, I'd try to take the situation in hand and explain that you, as employer or parent, are not going to be liable for the criminal charges that could result from "free music downloads" and so on.