1. BITTORRENT
May22,2013
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By
K Ravi Teja Varma
09131A1272
B. Tech, 8th Sem

2. CONTENTS
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•Introduction
•Types Of Data Sharing
•Traditional Client-Server Downloading
•Peer-Peer Downloading
•Gnutella Network
•Why BitTorrent?
•What actually a BitTorrent is?
•BitTorrent Terminology
•How BitTorrent works?
•Downloading Files Using BitTorrent
•Seeding Torrent
•How to create a dot torrent file
•Conclusion
•References

3. INTRODUCTION
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• Humans tend to share things.
• As electronic data plays a vital role these days, they acquire
the “sharing” attribute.
• Sharing electronic data(emails, ebooks, multimedia files) is the
need of the hour.
• Data sharing must be fast enough as we are now moving to 3G
and 4G technologies, users expect data sharing at high speeds.

4. TYPES OF DATA SHARING
 Manual Sharing Using Removable Media: Such as USB
drives, External Hard disks.
 Centralized Servers of Computer Networks: Network of
computers interconnected for sharing resources and
information via a central server.
 Distributed Peer-to-Peer networking: Is a Computer network
where each system in the network acts as client or server
allowing shared access of resources without the need of
central server.
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5. TRADITIONAL CLIENT-SERVER DOWNLOADING
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•You open a Webpage 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 Web page 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).

6. CONTD.
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•The transfer speed is affected by a number of variables, including the
type of protocol, the amount of traffic on the server and the number of
other computers that are downloading the file.
•If the file is both large and popular, the demands on the server are great,
and the download will be slow.

7. PEER-PEER DOWNLOADING
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•In peer-to-peer sharing, a software program is used instead a Web
Browser to locate computers that have the file user want.
•These are ordinary computers like the users, they are called PEERS.
• The process works like this:
• You run peer-to-peer file-sharing software (for example,
a Napster program or Gnutella) 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.

8. CONTD.
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•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 computer's 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.

9. CONTD.
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•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 .

10. GNUTELLA NETWORK
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How a Gnutella client finds a song
Given that there is no central server to store the names and locations of
all the available files, how does the Gnutella software on your machine
find a song on someone else's machine?
The process goes like this:
• Type the name of the song or file we want to find.
• Your machine knows of at least one other Gnutella machine
somewhere on the network.

11. CONTD.
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•Your machine sends the song name you typed in to the Gnutella
machine(s) .
•These machines search to see if the requested file is on the local hard
disk. If so, they send back the file name (and machine IP address) to the
requester.
•At the same time, all of these machines send out the same request to
the machines they are connected to, and the process repeats.
•A request has a TTL (time to live) limit placed on it.

12. CONTD.
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 A request might go out six or
seven levels deep before it
stops propagating. If each
machine on the Gnutella
network knows of just four
others, that means that your
request might reach 8,000 or so
other machines on the Gnutella
network if it propagates seven
levels deep.

13. CONTD.
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•It is an extremely simple and clever way of distributing a query to
thousands of machines very quickly.
•This approach has one big advantage -- Gnutella works all the
time , as long as you can get to at least one other machine running
Gnutella software, you are able to query the network.
•No court order is going to shut this system down, because there is
no one machine that controls everything.

14. WHY BITTORRENT?
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•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 -- one of developer
Bram Cohen's primary goal.

15. WHAT IS BITTORRENT?
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•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 pop-up
advertising.
•The most popular video, audio or software files can be transferred
faster and cheaper by using BitTorrent.

16. BITTORRENT TERMINOLOGY
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Leeches - People who download files but do not share files
on their own computer with others.
Seed or seeder - A computer with a complete copy of a
BitTorrent file (At least one seed computer is necessary for a
BitTorrent download to operate).
Swarm - A group of computers simultaneously sending
(uploading) or receiving (downloading) the same file.
.torrent - A pointer file that directs your computer to the file
you want to download.
Tracker - A server that manages the BitTorrent file-transfer
process.

17. HOW BITTORRENT WORKS?
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•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 are connected computers
that have all or a portion of the file and are in the process of sending
or receiving it.
•The tracker helps the client software to trade pieces of the file we
want with other computers in the swarm. Your computer receives
multiple pieces of the file simultaneously.

18. CONTD.
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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.

19. DOWNLOADING FILES USING BITTORRENT
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•Just like you need a URL: www.google.com to go to that site
and download content.We need a „torrent file‟ that tells
BitTorrent the necessary information to download the content.
•Websites like legaltorrents.com offer all kinds of torrents.
•Once you have obtained torrent file, you need to import it to
BitTorrent:
•Click File->Add Torrent or Press CTRL+O.
•Double click on Torrent file.

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21. SEEDING TORRENT
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•Seeding is where you leave your BitTorrent client
after you finish download to help distribute it.
•BitTorrent will continue seeding until you remove it
(Right click the torrent and hit Remove) .

22. HOW TO CREATE A .TORRENT FILE
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23. CONTD.
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24. May22,2013
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Creating a torrent file

25. CONCLUSION
 News of increased adoption of this revolutionary protocol
continues to emerge, and this seems to be a rich area for
continued research in computer networking, with significant
potential benefits to society.
 If BitTorrent and similar protocols do find a legal place in the
internet, it will certainly help to pave the way for distributing
rich media on the internet, and provide the impetus for new
innovations.
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26. REFERENCES
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1. http://computer.howstuffworks.com/bittorrent.htm
2. http://en.wikipedia.org/wiki/BitTorrent
3. http://computer.howstuffworks.com/file-sharing.htm
4. http://en.wikipedia.org/wiki/World_Wide_Web
5. http://en.wikipedia.org/wiki/Computer_network
6. http://www.bittorrent.com/help/guides/beginners-guide

27. THANK YOU...!
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