BitTorrent Protocoland a Torrent Client Software

Contents1. Introduction2. History3. BitTorrent

• P2P

4. Implementing BitTorrent5. BitTorrent Terminology6. How BitTorrent Works

• Torrent File• Torrent Client

7. Legal Aspects8. Summary9. Quires

Introduction

• BitTorrent is a Peer-to-Peer file sharing protocol used for distributing large amounts of data over the Internet.

• BitTorrent is one of the most common protocols for transferring large files.

Introduction

• It has been estimated that peer-to-peer networks collectively have accounted for roughly 43% to 70% of all Internet traffic .

• The name Bit Torrent is also used to describe the official Bit Torrent client Software.

History

Programmer Bram Cohen designed the protocol in April 2001 and released the first

available version on July 2, 2001It is now maintained by Cohen's company,

BitTorrent, Inc. Currently

BitTorrent or

simply Torrent

•BitTorrent is a way to transfer files of just about any size quickly and efficiently. Works on peer to peer network•It works by breaking files up into small pieces. •The file is downloaded piece by piece from one or many different sources.• It's efficient because you get faster downloads using a lot less bandwidth. •The name BitTorrent is also used to describe the official BitTorrent client.

What is peer to peer P2P

• A peer-to-peer (abbreviated to P2P) computer network

• In which each computer in the network can act as a client or server for the other computers in the network.

• It allows sharing various resources such as files, peripherals, and sensors without the need for a central server.

Implementing BitTorrent

What you need ?

Only a Client Software and Internet Connection.

BitTorrent TerminologyBlock A block is a piece of a file. When a file is distributed via BitTorrent, it is broken into smaller pieces, or blocks. Typically the block is 250kb in size, but it can vary with the size of the file being distributed. Breaking the file into pieces allows it to be distributed as efficiently as possible. Users get their files faster using less bandwidth.

Client the BitTorrent software used to download and upload files.

BitTorrent Terminology

•Leech usually refers to a peer(computer) that is downloading while uploading very little, or nothing at all.

•SeedSeed is a computer or peer which currently uploading the file . It has complete copy of the file. Working as a Server

BitTorrent Terminology

Torrent file

a file which describes what file or files are being distributed, where to find parts, and other info needed for the distribution of the file.

BitTorrent Terminology

Tracker server that keeps track of the peers and seeds in a swarm. A tracker does not have a copy of the file itself, but it helps manage the file transfer process.

Swarm a group of seeds and peers sharing the same torrent.

How BitTorrent Works

Bit Torrent Working

To share a file or group of files, a peer first creates a small file called a torrent file using Torrent Client Software

PeerPeer

File to SendFile to Send

Torrent FileTorrent FileCreate Torrent File

Torrent Client

Software

Torrent Client

Software

Seeder

send it to other peer

Bit Torrent Working

Then Peers that want to download the file must first obtain a torrent file for it and connect to the specified tracker, which tells them from which other peers to download the pieces of the file.

PeerPeerTorrent FileTorrent FileTorrent Client

Software

Torrent Client

Software

leech

Download Torrent File

Leech starts torrent Client software and connects to the Tracker which tells it from where to download (IP of uploading peer)

Working

Peer 1

creates a torrent file (using Torrent Client)

Sends it peer 2

Peer 2

tracker

Connect to tracker

Data File

Tracker finds that peer1 has file so it sends the address of peer 1 to peer 2

uploading (seeding) Start downloading (leecher)

Piece by Piece

Data File

Peer 1 wants to send Data File to Peer 2

How works on Internet when multiple peers

tracker

Peer 1

finds the seeder

Peer 2 This Peer also wants to download

Peer wants to download file so first downloads torrent and start it

finds the seeder connectconnect

seeder/ leecher

seeder

Spreading File across all Clients

Tracker keeps track of seeds and leeches

Thus BitTorrent Protocol provides flood like spreading of

a file throughout many peer computer nodes. Without need

of a central data server

swarm

Torrent File•It has extension .torrent

•A torrent file stores metadata used for BitTorrent.

• Simply, a torrent is data about a target file, though it contains no information about the content of the target file.

•The only data that the torrent holds is information about the location of different pieces of the target file.

•Torrents work by dividing the target file into small information chunks, found on an unlimited number of different peers(seeds/leechers).

•Through this method, torrents are able to download large files quickly.

• torrent file contains the URLs of many trackers and integrity metadata about all the pieces.

Torrent File’s Content

Torrent ClientsTorrent Client is a software which works on BitTorrent protocol it is used to download and upload file. It can also create Torrent files which can be sent to the receiver peer.Various Torrent Client software are available in market they are from sharewares to freeware and also some open source some of them are :

µTorrenta Bit Torrent Client

µTorrent is a freeware, closed source BitTorrent client now owned by BitTorrent, Inc. It is the most

widely used BitTorrent client

Main InterfacePlay, Pause, Stop Buttons

Play, Pause, Stop Buttons

Seeds and Leeches

Seeds and LeechesDownloaded and

RemainingDownloaded and

Remaining

Peers Currently Connected

Seeder’s IP AddressSeeder’s IP AddressSeeder’s Client SoftwareSeeder’s Client Software

Properties of µTorrent Client

• its very tiny in size take less than 1 MB for installation

•It uses less system resources than other Torrent Clients

•Its Freeware

•Provides App and Plug-ins for extra utilities.

•Supports DHT,PEX and Magnet Links

Other Techniques used with BitTorrent Protocol

PEX or Peer exchange•In the original design of the BitTorrent file sharing protocol, peers relied upon a central computer server called a tracker to find each other •PEX technology allows each peer to directly Update the swarm as they connects to it without need of Tracker Server.

TrackerKeeps Track

TrackerKeeps Track

PeerPeer

PeerPeer

PeerPeer

PeerPeer

PeerPeer

PeerPeer PeerPeer

PeerPeer

PeerPeer

PeerPeer

Normal BitTorrent Protocol with PEX

Peer can Keep track each other

PEXadvantage

PEX increases the speed, efficiency, and robustness of the BitTorrent protocol.

DHT : Distributed Hash Table•DHT is also PEX like technique which decentralized network that µTorrent can use to find more peers without a tracker.

What this means is that your client will be able to find peers using Magnet Link even when the tracker is down, or doesn't even exist anymore

TrackerStores IP and sends to peer

TrackerStores IP and sends to peer

PeerPeerPeerPeer

Normal

DHTcontains IP addresses

(Hash values)and DHT is stored on

Peers

DHTcontains IP addresses

(Hash values)and DHT is stored on

Peers

with DHT

Peer Uses DHT to connect with other peer so they don’t need Tracker

DHT : Distributed Hash Table

PeerPeer

PeerPeer

PeerPeer

Hash Value (IP)Hash Value (IP)

Hash Value (IP)Hash Value (IP)

Hash Value (IP)Hash Value (IP)

Hash Value (IP)Hash Value (IP)

Hash Value (IP)Hash Value (IP)

Hash Value (IP)Hash Value (IP)

Hash Value (IP)Hash Value (IP)

Hash Value (IP)Hash Value (IP)

Hash Value (IP)Hash Value (IP)

Hash Value (IP)Hash Value (IP)

DHT

Swar

m IP

s

Magnet Links•Magnet links though are just links, they have no files associated with them just data.

•In the case of BitTorrent, they hold the hash value of the torrent which is then used to locate copies of the files among the peers in a DHT

• They may also hold file name data or links to trackers used by the torrent.

Magnet link also contains IP and Hash Value of Torrent used to

locate Peers

Magnet link also contains IP and Hash Value of Torrent used to

locate PeersPeerPeer

Advantages of BitTorrent• It’s a efficient way of sending large files with high speed.

•We can pause resume and again start sharing

•Better technology than sending file by•Email attachment•Online File Hosting•FTP

•File can be shared easily over large no. of users without need of Central Data Server

• computer share with each other using p2p over internet

Limitations of Bit Torrent

•If there is no seeders then there is no download means if nobody is uploading then other peers cant download file.

•That’s why Old or unpopular files are hard to find because nobody uploads them. While new popular content is easy to download.

•Torrent files are too flaky(fake) due to excessive popularity it means there are fake torrent file possible which may download virus or other harmful content.

Legal Aspects• Use of the BitTorrent protocol for copyright material and other illegal purposes has led to a variety of novel legal issues.

• While the technology itself is perfectly legal

• At any given instant BitTorrent has, on average, more active users (connected) than YouTube and Facebook combined.

•It is possible that if you are downloading copyrighted material illegally then you can be caught through your IP address Under Cyber Crime

•in 2010 a USA authority sued people which were downloading the copyright material using bit Torrent and about 16,200 Court Cases were filed between March and September 2010

SummaryBitTorrent is a way to transfer files of just about any size quickly and efficiently.

It works by breaking files up into small pieces. The file is downloaded piece by piece from one or many different sources.

It's efficient because you get faster downloads using a lot less bandwidth.

Thank you !

Queries ?Prepared by Bharat Rajcontact me at:www.facebook.com/rajbharatraj