Murphy's Law: No BitTorrent Tracker? No Problem!

Posted 11/18/2009 at 11:00am | by David Murphy

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Half the internet says The Pirate Bay is dead; The other half says the first half has no idea what it's talking about. Popular BitTorrent index The Pirate Bay is never without controversy, it seems. But is the site's latest move to kill its BitTorrent tracker for good really that much of a white flag? I don't think so, because decentralized BitTorrent tracking has already been here for quite some time now. If anything, The Pirate Bay is just trying to cover its poop deck from additional legal threats.

Here's the deal. For the last many years, anyone could head on over to The Pirate Bay site, do a quick search for a piece of content, download the associated .torrent file, and connect up to The Pirate Bay's tracker. The tracker would, in turn, find you a number of peers to connect to and your BitTorrent client of choice would commence the download of bits and pieces of your file from these multiple sources. Easy.

When a tracker fails to work--or gets forcibly removed from the Internet--you can keep on transferring bits and pieces of a file to those you're already connected to. If you want to start a new download, however, you'll be unable to find any peers seeding the file for you. The same holds true in reverse: Without a tracker, others on the Internet won't be able to connect to you either.

To solve these problems, BitTorrent has embraced two technologies that, together, transform the art of downloading files into a truly peer-to-peer solution: DHT and magnet links. DHT, or distributed hash tables, are a method of decentralizing BitTorrent exchanges by using the power of the group to conduct the peer discovery process. Instead of downloading a .torrent file and connecting to a tracker to bootstrap your way into the network of your peers, your BitTorrent client automatically goes out and locates the files you want in the cloud, bypassing the tracker entirely. In fact, you'll often find more available peers for downloading snippets of your files through the use of DHT than trackers themselves.

Magnet links are a similar concept, different execution. Instead of hosting .torrent files for download, a site need only create a special hyperlink that contains a hash--or small representation--of the file in question. When pulled up in a supported BitTorrent client, the hash of the magnet link becomes the basis for the DHT-based acquisition of new peers and file snippets to download.

What's the benefit to you, good consumer-turned-legal-BitTorrenter? For starters, this decentralization allows you to bypass the frustrations of missing trackers for torrents and simultaneously open up your downloading world to even more connections than what you would otherwise find from a conventional tracker. Magnet links might not seem like the biggest improvement in the world, but they carry on this theme of decentralization and remove the necessity of index sites from the equation entirely. After all, a magnet link is essentially a URL for your BitTorrent client--one that can be shared in a Web forum, pasted into an IM conversation, or attached to the bottom of a weekly open-source column.

For a site like The Pirate Bay, however, these not-really-new technological advancements could be seen as more of a legal salvation than anything else. It's no secret that the site's biggest argument against its illegality is that it merely provides users the location for downloading copyright material through .torrent links--analogous to a Web site that would host the instructions on how to make an explosive device. It's not the site's fault for how what its users do after-the-fact. Although, for what it's worth, the issue that The Pirate Bay hosted its own tracker for allowing users access into the BitTorrent process does lend The Pirate Bay a bit more culpability in these matters.

Nevertheless, the Promised Land for BitTorrent decentralization isn't quite here yet. In a perfect world, one would be able to use the Cloud as a search engine for more than just these unique file hashes. Not only would that render sites like The Pirate Bay relatively useless--ignoring, of course, the more "elite" communities of BitTorrent users on the Web--but it would allow users a one-stop shop for acquiring new files directly through their client of choice. Gnutella tried this to poor results, as its built-in search functionality never quite grew as a result of the service's bandwidth costs for doing so--hence the introduction of DHT.

Still, there is a certain sense of martyrdom in The Pirate Bay's decision to kill its tracker. In some strange way, The Pirate Bay has euthanized itself to further the propagation of a decentralized BitTorrent services for all. Maybe they really do care more about principle than piracy after all...

David Murphy (@ Acererak) is a technology journalist and former Maximum PC editor. He writes weekly columns about the wide world of open-source as well as weekly roundups of awesome, freebie software. Befriend him on Twitter, especially if you have an awesome app or game you're dying to recommend!