( Dry but lengthy piece written for Metro magazine earlier in 05 )
Like the mp3 sharing client Napster many years before it, the Bit Torrent application has recently become the public face of peer to peer ( P2P) file sharing. While Napster provided an innovative way for users to browse and share Mp3 files, the Bit Torrent model extends on this by sharing not just user files, but user bandwidth as well. Inevitably, the improved download speeds of Bit Torrent have attracted a large userbase, and in turn, copyright enforcers and subsequent media coverage. Despite some bad press, Bit Torrent has much to offer online media creators, publishers, distributors and audiences alike, as it allows small operators to distribute large popular files, by cleverly utilising the bandwidth of the downloading users.
Harnessing The Network
“The key to scaleable and robust distribution is to tap the unutilized upstream broadband capacity of your customers. It’s free and abundant. Their contribution grows at the same rate as their demand, creating limitless scalability for a fixed cost.”
– From bittorrent.com
Somehow it’s not surprising to learn that a tool being used for 35% of all internet traffic within two years of it’s release, wasn’t the product of a monolithic IT department, but the carefully crafted code of a 29 year old programmer who enjoys recreational mathematics, network protocols and ‘designing twisty puzzles’. The success and rapid uptake of Bram Cohen’s Bit Torrent application, revolves around a central insight gleaned from applying his puzzle solving skills to network traffic bottlenecks : most users don’t utilise their upload bandwidth. With this in mind Bram set about designing an application that not only allowed a file to be downloaded ( & uploaded) from many places at once, but defined from the start that all downloaders must share and upload the file they are downloading. With Bittorrent, everyone who wants the file helps distribute it.
The Mechanics of Bit Torrent
From the perspective of a downloader, or from someone wishing to offer a file through Bit Torrent, it’s key components are: ‘.torrent’ files, ‘seeders’, ‘trackers’ and Bit Torrent clients or applications. A torrent file is a very small ( usually less than 50k ) reference file. If a large file is available for download via Bit Torrent, it is this small torrent file that is downloaded first. Those wishing to distribute a large file, would need to both create a torrent file about their large file, and then offer this torrent file for download. The torrent file points a Bit Torrent client to a tracker, which is an internet server for co-ordinating the actions of Bit Torrent clients on the network. A seeder is a client on the BT network who has the original or a complete version of whichever file the torrent file is referencing.
For example, a small movie maker might upload a large 100mb movie to their webserver, and offer a torrent file of that movie. Traditionally, if their site or movie became quickly popular, this might provide huge bandwidth hosting bills. With Bit Torrent, the moviemaker would only need to initially ‘seed’ the torrent file, then as others in turn became ‘seeders’ of the movie as they downloaded it, they would also boost the available bandwidth for any future visitors to download the movie from. Any sudden jumps in popularity would only mean lots of new users downloading the small torrent file, a minor net traffic concern, and the bulk of downloading would be distributed amongst ‘seeders’ who already have the movie, all co-ordinated by the Bit Torrent client and tracker. Within this framework, a ‘leecher’ in BT terminology is someone who does not have a complete copy of the file yet, and although they may be uploading parts of it to others, they are not yet capable of seeding the file by themselves. Given that files only remain available as long as there is at least 1 seeder, there is a strong emphasis within the BT community on keeping any downloaded files open for others to access for as long as possible, even after you have downloaded the complete file.
Also worth noting is that Bit Torrent breaks large files into smaller fragments, so that large files can be reassembled from many different sources at once. Each BT client is optimised to take advantage of the best connections to the missing file pieces it needs, whilst simultaneously providing an upload connection for pieces it already has. For these reasons, BT speeds can be much faster than those in other P2P networks, and can scale very quickly to adapt to large volumes of downloaders.
Finding Torrents
“Although a number of very large BitTorrent-based web sites have been taken down recently, downloads of BitTorrent have only gone down slightly. There’s a widespread belief that BitTorrent is used almost exclusively for warez… but that impression is simply untrue.”
– Bram Cohen
While attempting to outlaw mobile phones or even email, because they facilitate criminal activities for some people, may seem absurd, it is the Motion Picture Association of America’s
current response to illegal online distribution. In December 2004, they tried to stop several high profile torrent tracker sites – which immediately triggered the emergence of dozens of others and the development of further decentralised applications such as eXeem, which utilise torrents, but do not require centrally organised ( and therefore closable ) trackers. While search engines will reveal a long list of popular tracker sites full of popular media, it’s important to remember Bit Torrent is just a protocol which efficiently distributes large files across networks. As such, it has been widely embraced, and only a fraction of it’s uses are illegal. Some popular and legal Torrent sites include :
– The Linux Mirror Project ( www.tlm-project.org) – Linux distribution ISO images as downloadable torrents.
– Chomsky Torrents ( www.chomskytorrents.org ) – A filesharing resource for videos of Noam Chomsky’s talks.
– Filesoup (www.filesoup.com/forum ) – open source applications, games, audio, independent video etc.
– Beastie Boys Videos (www.beastie boys.com) – Using torrents to distribute high resolution videos.
– Indy Torrents (http://indytorrents.org ) – Indymedia audiovisual materials.
– LegalTorrents ( www.legaltorrents.com ) – legally downloadable, freely distributable creator-approved files, from electronic music to movies and books.
-Beyond TV ( http://beyondtv.blogspot.com ) – Alternative news.
– Etree ( http://bt.etree.org ) – Shared live concert recordings of trade friendly artists.
Making Torrents
Despite, or perhaps because of it’s sophistication, Bit Torrent still faces a few hurdles to win broader adoption by net users. Most net utilities, plug-ins and applications that require extra steps deter many users, as does any steepness of learning curve. Nonetheless, once the improved download speeds and distribution savings of BT are felt, users generally make the necessary steps to further harness BT power. Most BT clients, which are available for most platforms, allow simple creation of torrent files relating to any large files a user wishes to distribute. Creating that reference file is easy, however a key part is the choice of a tracker address for embedding within the torrent file – so that when users download the torrent file, their client will connect with the tracker and co-ordinate the distributed down and uploading to and from the users’ machine. The different BT clients approach this in various ways, which should be easily understood through the client manuals. Various torrent creation help sites and stand alone torrent creation applications also exist ( see http://writtorrent.sourceforge.net ), and software evolution should continue to make this process less of a headache.
Torrent Developments
As automated publishing systems such as blogs and content management systems continue to integrate the publishing of audio and video media ( try googling podcasting and video blogging ), bandwidth concerns and bills are becoming of increasing concern to online publishers. It is testament to the value of Bit Torrent then, that the easy integration of torrent publishing into content management systems is being currently pursued from many angles. Representing one of the best attempts so far, is Blog Torrent ( www.blogtorrent.com), which claims to ‘let you post video or other large files as easily as you post text’. Videora.com ( windows only ) combines BitTorrent and RSS to automatically download a computer user’s favorite videos. Other notable application hoping to integrate torrent publishing is FireANT, (www.antnottv.org) which currently automates video blog feeds via RSS.
Torrent Resources
– Official Bit Torrent website (http://bittorrent.com) and home of Bram Cohen’s original client and tracker.
– Wikipedia torrent guide ( http://en.wikipedia.org/wiki/Torrent)
– Bit Torrent Applications & Guide ( http://www.slyck.com/bt.php?page=1 )
Jean Poole
– is a Melbourne based writer and video artist.