Often when people hear the term “peer-to-peer file sharing”, they think of torrents, illegal swapping of the latest movies and music, and resulting lawsuits by the record or movie industries for piracy.  That does happen; however, file sharing encompasses much more than ripping off the latest hits.

Peer-to-Peer, or P2P, is the most widely used form of file sharing. It has become a big and growing part of the Internet, already accounting for 50-70% of consumer network traffic, with millions of P2P clients downloaded and in use.  In 2004, an estimated 70 million people were busily sharing files, and doubtless many more now.

But P2P is not the only means to share files over the Net. It should not be confused with file hosting, which uses the more familiar client-server architecture of the Internet to stream files to users from big, centralized Web servers.

In its purest form, Peer-to-Peer is strictly that: users’ computers directly linked across the Net to their peers; that is, other users’ computers.  They join in a network of equals, each machine devoting some fraction of its computing power, bandwidth, and memory to the network, ideally without any need for a central coordinator. In fact, P2P works pretty much the way the Web was originally intended to function.

Collaborative computing

Civilization is the story of how ever-larger tasks can be done, and done much more efficiently, with cooperation. As a form of collaborative computing between users, P2P is another step on the way. It’s a way of spontaneously organizing low-level networks that can provide a cheap alternative to enormous webfarms with expensive servers for businesses and research institutions.

Collaborative computing is not only for distributing content. It is chiefly meant to aggregate the combined computing power of thousands of individual PCs as a virtual supercomputer to solve massive problems, like searching the sky for signs of life, or even rendering animation.

It has been embraced by NASA with projects like the SETI@home radio scan for alien broadcasts by utilizing a vast array of otherwise idling PCs to crunch data. Other examples are much closer to home. For instance, millions of people constantly rely on P2P connections without even realizing it every minute, as it is commonly employed in instant messaging and online chat, and by Skype and VoIP.

However, no form of file sharing is inherently risk free, because it necessarily opens your computer to the Net.

Recently, for example, some rather frightening vulnerabilities in printing over the Internet were discovered.  Printing documents from work at home or vice versa over the Web is a convenience that many users take for granted.

But researchers at Columbia University found that theoretically a hacker could take control of certain older printers linked online and use them to copy private information, take over secure networks — or even make the printers catch fire.  While that thankfully hasn’t happened outside the lab, it shows the potential for real-world mischief of file sharing.

Torrential dangers

It’s no secret that many people looking at P2P are only interested in downloading movies and music for free.  Torrent services, like BitTorrent or the infamous Pirate Bay, use special software to connect users’ computers to each other directly to share files of common interest. Large files – such as movies – are broken down into small chunks, to be reassembled after downloading. A user can obtain chunks from multiple peers even as others are obtaining chunks from his or her own computer.

Along with security issues of opening up a directory on your computer to the world, there are also serious, persistent questions of legality. P2P has been notoriously used to distribute copyrighted and also outright illegal material.  The DMCA, or Digital Millennium Copyright Act, was passed unanimously by Congress in 1998 to attempt to stem the flow.

However, bills in the works right now, SOPA (Stop Online Piracy Act) and the Protect IP Act are much more severe. They would, according to critics including Facebook and Google, require a national firewall to block copyrighted material. Worse, they would punitively block entire domains arbitrarily just on suspicion, with no mechanism for prevention or appeal.

Whether the national and international outrage this has raised will have any effect on the passage of these bills, the trend everywhere seems towards increased control and less freedom. The chances of being caught or accused unfairly and the penalties are steadily increasing as Big Media becomes ever more desperate to maintain total control over their products.

As for the basic legality of it all: courts have ruled that file sharing as such is not illegal. It all depends on the content, who owns it, and who controls it. The issues are complicated and technical as well as legal. Napster, for example, the first popular P2P system, was finally brought down because the service controlled the system with a server, and hence was therefore liable for what the server carried.

Later networks have become more effectively decentralized, but efforts by the entertainment industry and law enforcement to staunch illegal activity have not diminished. So it is that SWCP every now and then is required by law to pass on DMCA threats against customers who have been singled out.  They have been accused – not necessarily correctly, it should be noted – because there is no provision for anonymity in basic P2P technology or protocols; additional special steps need to be taken.

Not only that, but any search for files held by a truly decentralized P2P network without central indexing servers requires that all peers be checked, or that each peer maintains an entire index of everything on the network. With the first method, there’s no way to hide what you’re looking for from everyone else on such a system, and the latter method slows things down.

Other legal issues involve Net Neutrality and bandwidth-throttling for the huge amount of bandwidth that consumers eagerly sharing films can consume. A more immediate danger to users, however, is that security firms report that many P2P torrent data streams have been dangerously poisoned by viruses and other malware. These are not only the products of virus writers, some studios have been known to upload fake hits or apps in order to punish the illegal downloader.

But logically, in any case, if somebody’s laptop in Zanzibar can locate yours to share the latest superhero epic, what’s to stop the corporate owners of the picture and their lawyers from finding you if they want to as well?

The bottom line is this: if you’re going to download media, don’t indiscriminately file share. Get your movies and music safely from legitimate sites. If you want to download files, the best way to find them is with the Miro program. Formerly known as “Democracy Player”, it’s a combination online video player and BitTorrent client. It has a searchable library of thousands of legal free videos.

Or turn to commercial file-hosting sites such as iTunes, Hulu Plus, or Netflix. Peace of mind can be well worth the pennies you pay.

One final word of advice: if you do download or stream videos, please do not do so via Wi-fi on a shared connection with others, for instance, at a coffee shop. It hogs bandwidth, and can slow down everybody’s connection there as to make them almost unusable.