Post on 13-Dec-2014
description
transcript
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.