File Sharing with BitTorrent

Justin Mongiardo
Coquitlam, British Columbia, Canada

Peer-to-peer (P2P) networks are a popular way of sharing files over the web. There are a variety of options available to those who want to transmit and download files through a P2P setup. However, one of the most efficient options is to use a BitTorrent. BitTorrent protocols allow a rather large amount of data to be transmitted quickly over a P2P network.

Sharing a file through a BitTorrent protocol begins when the file's owner creates a small "torrent" file. This contains vital information about the file to be shared and the host computer. Essentially, the torrent file allows a user to connect to other computers in a P2P network and transfer the desired files. This sounds simple enough, but it actually shows a rather complex development scheme created by Bram Cohen. He first began working on the BitTorrent protocol in 2001, and within three years had started BitTorrent, Inc. to maintain and develop his new technology.

One benefit of torrents is that they put less of a strain on the original distributor's system. Bandwidth is shared by everyone who downloads the original file or collection. In essence, each person who downloads a file becomes responsible for helping to share that file. Thus, when a new user requests a download, information is transmitted from several machines in the P2P network. The more popular a file is, the more people who download it and, subsequently, can help contribute to future download requests. Additionally, bandwidth is efficiently utilized as users upload new content at the same time they are downloading files.

The use of a BitTorrent tracker is necessary to conduct P2P file sharing through this method. The tracker helps facilitate communication between peers in a P2P network. It essentially functions as a server and coordinates the actions of the peers involved in BitTorrent sharing. Clients must interact directly with the tracker to download files.

To make finding files easier, users may access a BitTorrent index. These contain a listing of files with .torrent extensions. Other information and descriptions are usually included as well. BitTorrent indexes are managed by a website. In many cases, these websites also allow access to the necessary tracker. Thus, finding and downloaded the desired file is made much simpler.

Establishing security in a BitTorrent network can be facilitated by using a "private tracker." This means, in order to use a tracker, the user must have specific permission. Permission may be granted by registering by a username and password. However, some private trackers accept new users on an invitation-only basis. Access to a BitTorrent may also be restricted based upon a user's uploads. Those who do not contribute enough content may be denied download access. While restricted access might seem like a problem, these types of trackers are associated with more efficient torrent services. Less users and higher regulation means better quality content and faster downloads.

Currently there are more than 160 million estimated BitTorrent users. This number is expected to grow as more and more people become involved in file sharing. Unfortunately, some people have used BitTorrent for illegal sharing of copyrighted materials. However, this has not discouraged people from continuing to use this well-developed protocol to share information easily and efficiently.