BitTorrent – A revolution in P2P technology

By | March 20, 2014

ABSTRACT :

In today’s world only torrents download data at a higher rate even though our internet capacity is low. There are famous websites like kat.ph, torrentz,  who provide torrents for any application/software/movie/MP3. With BitTorrent, those who get your file tap into their upload capacity to give the file to others at the same time. The key to scalable and robust distribution is cooperation. Cooperative distribution can grow almost without limit, because each new participant brings not only demand, but also supply. Instead of a vicious cycle, popularity creates a virtuous circle. And because each new participant brings new resources to the distribution, you get limitless scalability for a nearly fixed cost. Thus with BitTorrent free speech no longer has a high price.

INTRODUCTION

BitTorrent is a protocol that enables fast downloading of large files using minimum Internet bandwidth. It costs nothing to use and includes no spyware or popup advertising. Because of the nature of this protocol, large files can be handled more efficiently than thetypical client/server method. The protocol was designed in April 2001 and implemented in Summer 2002 by programmer BramCohen, and is now maintained by BitTorrent.

WORKING

To understand how BitTorrent works and why it is different from other file-serving methods like,Traditional Client-Server Downloading. Let.s examine what happens when you download a file from a Website. It works something like this:

BitTorrent working

BitTorrent working

Client-server downloads process

Lets examine what happens when you download afile from a Web site. It works something like this:

  • You open a Web page and click a link to download a file to your computer.
  • The Web browser software on your computer (the client) tells the server (a central computer that holds the Webpage and the file you want to download)to transfer a copy of the file to your computer.
  • The transfer is handled by a protocol (a set of rules), such as FTP (File Transfer Protocol) or HTTP (Hypertext Transfer Protocol).

PEER-TO-PEER NETWORKING

Peer-to-peer file sharing is different from traditional file downloading. In peer-to-peer sharing,  you use a software program (rather than your Web browser) to locate computers that have the file you want. Because these are ordinary computers like yours,  as opposed to servers,  they are called peers. The process works like this:

peer-to-peer working

peer-to-peer working

  • You run peer-to-peer file-sharing software(for example, a Gnutella program) on your computer and send out a request for the file you want to download.
  • To locate the file, the software queries other computers that are connected to the Internet and running the file-sharing software.
  • When the software finds a computer that has the file you want on its hard drive, the download begins.
  • Others using the file-sharing software can obtain files they want from your computers hard drive.

The file-transfer load is distributed between the computers exchanging files, but file searches and transfers from your computer to others can cause bottlenecks. Some people download files and immediately disconnect without allowing others to obtain files from their system, which is called leeching. This limits the number of computers the software can search for the requested file.

PEER-TO-PEER DOWNLOADS PROCESS

What BitTorrent does ?

Unlike some other peer-to-peer downloading methods, BitTorrent is a protocol that offloads some of the file tracking work to a central server (called a  tracker). Another difference is that it uses a principal called tit-for-tat. This means that in order to receive files, you have to give them. This solves the problem of  leeching. With BitTorrent, the more files you share with others, the faster your downloads are. Finally, to make better use of available Internet bandwidth (the pipeline for data transmission), BitTorrent downloads different pieces of the file you want simultaneously from multiple computers.

Here’s how it works:

Working of BitTorrent protocol

  • You open a Web page and click on a link for the file you want.
  • BitTorrent client software communicates with a tracker to find other computers running BitTorrent that have the complete file (seed computers) and those with a portion of the file (peers that are usually in the process of downloading the file).
  • The tracker identifies the swarm, which is the connected computers that have all of ora portion of the file and is in the process of sending or receiving it.
  • The tracker helps the client software trade pieces of the file you want with other computers in the swarm. Your computer receives multiple pieces of the file simultaneously.
  • If you continue to run the BitTorrent client software after your download is complete, others can receive . Torrent files from your computer; your future download rates improve because you are ranked higher in the “tit-for-tat” system. Downloading pieces of the file at the same time helps solve a common problem with other peer-to-peer download methods
  • Peers upload at a much slower rate than they download. By downloading multiple pieces at the same time, the overall speed is greatly improved. The more computers involved in the swarm,the faster the file transfer occurs because there aremore sources of each piece of the file. For this reason, BitTorrent is especially useful for large, popular files. Itis important to note that the servers coordinate the BitTorrent download process and have been a key resource for anti-piracy units in identifying people downloading and sharing copyrighted material.

INSTALLING AND CONFIGURING BITTORRENT

To use BitTorrent for file downloads, you need to install the BitTorrent client software like Azureus, Bitcomet and µTorrent. You may also need to tweak your firewall and network router to accept BitTorrent files but first, here’s a synopsis of the steps:

  • Download and install the BitTorrent client software(go here to download). 
  • Check and configure firewall and/or router for BitTorrent (if applicable).
  • Find files to download.
  • Download and open the .torrent pointer file.
  • Let BitTorrent give and receive pieces of the file.
  • Stay connected after the download completes to share your .torrent files with others.

DISTRUBUTING WITH BITTORENT

If  you have a large file you want to serve, BitTorrent can help you make the best use of your available bandwidth. To make a file available as a .torrent file, you need access to a tracker and to a Web server.

ADOPTION OF BITTORENT

A growing number of individuals and organizations are using BitTorrent to distribute their own or licensed material. The most notable of these is BitTorrent Inc. which has amassed a number of licenses from Hollywood studios for distributing popular content atthe companys website. Independent adopters report that without using BitTorrent technology, with its dramatically reduced demands on networking hardware and bandwidth, they could not afford to distribute their files. Many sites imitating big BitTorrent trackers have turned to distribution of only legal material in general. With several different categories they often provide a working distribution method for parties who want tohave big material packets available for large audience without investing large amounts of money. Amazon S3 (Simple Storage Service), a scalable Internet-based storage service with a simple web service interface, comes with built-in BitTorrent support.

BitTorrent is often used to distribute free and opensource software, especially ISO images of Linux distributions. Most Linux distributions offer BitTorrent as one of the download methods for installation CDs. Blizzards World of Warcraft video game utilizes the BitTorrent protocol to send game updates to clients. Blog Torrent offers a simplified BitTorrent tracker to enable bloggers and non-technical users to run a tracker off their site. Blog Torrent also allows visitors to download a “stub” file which acts as a BitTorrent client to download the desired file, allowing users without BitTorrent software to benefit from it. This is similar to the concept of a self-extracting archive.The game GunZ- the Duel has a built-in BitTorrent client. Podcasting software is starting to integrate BitTorrent to help podcasters deal with the download demands of their  MP3  “radio” programs. Specifically, Juice supports automatically processing .torrent files from RSS feeds. Similarly,  some BitTorrent clients,  such as µTorrent,  are able to process web feeds and automatically download content found within them.

LEGAL DEFENCES

There are two major differences between BitTorrent and many other peer-to-peer file-trading systems, which advocates suggest make it less useful to those sharing copyrighted material without authorization.

First, BitTorrent itself does not offer a search facility to find files by name. A user must find the initial torrent file by other means, such as a web search.

Second, BitTorrent makes no attempt to conceal the host ultimately responsible for facilitating the sharing: a person who wishes to make a file available must run a tracker on a specific host or hosts and distribute the tracker address(es) in the .torrent file. While it is possible to simply operate a tracker on a server that is located where the copyright holder cannot take legal action, this feature of the protocol does imply some degree of vulnerability that other protocols lack. It is far easier to request that the servers ISP shut the site down than it is to find and identify every user sharing a file on a traditional peer-to-peer network. However, with the use of a distributed hash table (DHT), a tracker is no longer required, although they are often still used so that clients that do not support DHT can still connect to the swarm.Tracker is a tool designed to extract information and metadata about your personal data so that it can be searched easily and quickly. By using Tracker, you no longer have to remember where youve left your files. To locate a file you only need to remember something about it, such as a word in the document or the artist of the song. This is because as well as searching for files in the traditional way, by name and location, Tracker searches files contents and metadata

LIMITATIONS AND SECURITY VULNERABILITIES

BitTorrent does not offer its users anonymity. It is possible to obtain the IP addresses of all current, and possibly previous, participants in a swarm from the tracker. This may expose users with insecure systems to attacks.Another drawback is that BitTorrent file sharers, compared to users of client/server technology, often have little incentive to become seeders after they finish downloading. The result of this is that torrent swarms gradually die out, meaning a lower possibility of obtaining older torrents. Some BitTorrent websites have attempted to address this by recording each users download and upload ratio for all or just the user to see, as well as the provision of access to older torrent files to people with better ratios. Also, users who have low upload ratios may see slower download speeds until they upload more. This prevents users from leeching, since after a while they become unable to download much faster than 1-10 kB/s on a high speed connection.  Some trackers exempt dial-up users from this policy, because they cannot upload faster than 1-5 kB/s.BitTorrent is best suited to continuously connected broadband environments, since dial-up users find itless efficient due to frequent disconnects and slow download rates.

CONCLUSION

The BitTorrent protocol is still under development and therefore may still acquire new features and other enhancements such as improved efficiency. Thus  we can say that BitTorrent is not just a concept, but has an easy-to-use implementation capable of swarming downloads across unreliable networks. BitTorrent has been embraced by numerous publishers to distribute to millions of users.

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2 thoughts on “BitTorrent – A revolution in P2P technology

  1. puja

    Amazing post.Great way to explain these technical intricacies to laymen.Keep up the good work.

    Reply

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