Presented by

ABHISHEK ROYDEBASISH

MUKHERJEESUMAN HALDERBHANU PRATAP

JHA

PROTOCOLS

For data transfer over the network, protocols are used( to

ensure interoperability) .Some of them are HTTP,FTP,SMTP

etc..BitTorrent is also a kind of protocol..designed by Bram

Cohen in 2001

BitTorrent P2P

By the end of 2004, BitTorrent (BT) was accounting for as much as 30% of all Internet traffic.

– P2P traffic is 60% of all Internet traffic

P2P traffic is rising

5

Server Distributing a Large File

d1

F bits

d2

d3

d4

upload rate us

Download rates di

Internet

BitTorrent Approach

File transfer

1 2 3 4 5 6 7 8

8

Peers Help Distributing a Large File

d1

F bits

d2

d3

d4

upload rate us

Download rates di

Internet

u1u2

u3

u4

Upload rates ui

{1,2,3,4,5}

{1,2,3,4,5,6,7,8}

{1,2,3,4}

C1

C2

{1,2,3}

{1,2}

C3

C4

Clients ci

Piece Selection and Bencoding

Random First PieceRarest First Piece

Endgame

Error detection mechanism.torrent file contains hash which

works as checksum.After downloading a file it is checked

against the hash given within .torrent file,if mismatch

occurs,then the downloaded file is corrupted..

Chocking

When a peer receives a request for a piece from

another peer, it can refuse to transmit that piece. If this happens, the peer is said to

be choked

BT: publishing a fileBT: publishing a file

Web Server

Initialseeder

Tracker

Downloader:

ASeeder:

BDownloader:

C

Harry Potter.torrent

13

Sub protocols

1 . HTTP Protocol 2. PWP: Peer Wire Protocol

Operation

Why is it Important?

• It is used by millions of file sharers across the globe.

• Corporations and open source companies use it to save bandwidth.

Bandwidth Shaping

BitTorrent is usually used to transfer large sized files due to which the traffic over the ISPs increase to a large extent. To avoid such exploding traffic on their servers many ISPs have started to avoid the traffic caused by BitTorrent

Pollution Attack

Attacker requests all chunks from swarm and wastes their upload bandwidth.

1>The peers receive the peer list from the tracker.2>One peer contacts the attacker for a chunk of the file.

3>The attacker sends back a false chunk.

4>Attacker requests all chunks from swarm and wastes their upload bandwidth.

DDOS Attack

Solutions

Encrypt the packets so that the filters that sniff packets will not be able to

detect such packets belonging to BitTorrent

The peers which perform pollution attacks are identified by tracing their

Ips

Solution to DDOS attack is to have clients parse the response from the

tracker

Conclusion

• BitTorrent pioneered mesh-based file distribution that effectively utilizes all the uplinks of participating nodes.

• BitTorrent’s application in this information sharing age is almost priceless.

• BitTorrent can serve as an effective media streaming tool as well.