peer2peer
A closer look
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peer2peer
Outline
•General
•Networks
•Issues
•Future
Pure P2P
Hybrid P2P
Security Legality
Gnutella
FastTrack
Napster
eDonkey
BitTorrent
peer2peer
General
•
What is peer2peer?
– A transient network allowing computers running the same networking
program to connect with each other and access files stored on each
other’s hard drives1
•
How does this concept relate to what we have learned regarding
network architectures?
– From Raja’s previous lecture…
•
P2P networks enable users to share a range of files
– Media (music, movies, images)
– Software (applications, games)
– Other “content”
peer2peer
General
•
Benefits of P2P
– Scalability: As more users join, more files are available
– Simultaneous file transfers amongst arbitrary computers
– Enables users to identify the fastest route, based on various factors
• How does this relate to what we have learned regarding routing?
– From another one of Raja’s lectures...
•
There are two major forms of P2P networks
– Pure
– Hybrid
peer2peer
Pure
•
A pure P2P network operates using decentralized resources
– There is no centralized server; every peer acts as both a client, server,
and router
– Uses a flooding-based search technique; a broadcast query protocol which
then waits for responses
•
A modification to this architecture introduces the concept of
supernodes
• Supernodes (or superpeers) are powerful computers with high-speed
Internet connections. These supernodes handle the queries of nearby
users and house information about available files
•
Examples we will go over: Gnutella, FastTrack
peer2peer
Gnutella: Pure
•
3rd largest P2P network
– 2.2 million users
•
Developed by NullSoft, a subsidiary of AOL
– Was only offered on the website for a limited time, due to AOL removing
it from their servers
•
Programs
– LimeWire, BearShare, Morpheus
peer2peer
Gnutella: Pure
peer2peer
FastTrack: Pure
•
2nd largest P2P network
– 2.8 million users
•
Uses the concept of supernodes
– An index of available files is distributed amongst the supernodes. Each
user is not equal in this sense
– More efficient than homogenous peers in Gnutella
•
Programs
– KaZaA, Grokster, iMesh, Morpheus (previously)
peer2peer
Hybrid
•
A hybrid P2P network operates using centralized servers
– Handles functions such as search, chat, and initializing connection, but do
not host the actual files
– Maintains an index of all available files spread out amongst users
• Because of this, searching is much more efficient. Requests are sent
to the centralized server rather than to all connected users
•
These centralized servers can either be owned by the company, or
privately owned
– Legal implications of ownership?
•
Examples we will go over: Napster, eDonkey, BitTorrent
peer2peer
Napster: Hybrid
•
Brought P2P technology into the mainstream by facilitating the
exchange of music files (MP3)
– Developed by Shawn Fanning, a student at the Northeastern University
•
Was sued by the Recording Industry Association of America (RIAA)
for copyright infringement
– Numerous legal cases quickly followed, resulting in Napster shutting down
in September 2002
– The Napster brand was then purchased by Roxio and made into a payper-song service
peer2peer
Napster: Hybrid
peer2peer
eDonkey: Hybrid
•
Currently the largest P2P network
– 3.7 million users
•
Servers act as communication hubs and allow users to search files
– Servers can be added/removed by anyone, so server lists are updated
regularly
•
The most popular server was Razorback2, hosted in Belgium,
Germany
– Hosted an average of 1 million users
– As of February 2006, Razorback2 was shutdown by the Belgian Police
•
Programs
– eDonkey2000, eMule
peer2peer
BitTorrent: Hybrid
•
Works differently from hybrid networks such as eDonkey or Napster
– Users connect to a server or tracker, and download a particular file in
pieces from other clients, while simultaneously uploading.
•
Servers act as trackers
– The tracker keeps track of all clients in a swarm for a particular file
whether their copy of the file is partial or complete
– Usually the single point of failure
•
‘Tit for Tat’ principle
– In order to get files, you have to be sharing them
•
Programs
– BitTorrent, BitTornado, BitComet
peer2peer
Security
•
Many programs such as KaZaA come bundled with Spyware and
other unwanted software
•
Some estimate that up to 45% of popular keyword search results
(files for download) contain some sort of virus, not including
worms/trojans/spyware
•
Many accidentally share private information such as Outlook
database files, personal information, etc.
peer2peer
Pure vs. Hybrid: Legality
•
Pure P2P networks
– What legal benefits are there for choosing a pure P2P network structure?
•
Hybrid P2P networks
– Why was Napster shut down?
peer2peer
The future
•
MUTE – Simple Anonymous File Sharing
– Assigns a random MUTE virtual address for every client each time you
open the program
•
More encrypted networks using UDP
– Unlike TCP/IP which is not anonymous, more encrypted networks running
on UDP such as Manolito P2P (MP2P)
•
Internal incentives and rewards
– A P2P network which rewards users who upload with ‘credit’ to continue
downloading
•
The use of Darknets
– Darknets are small social P2P networks based on trust rather than
anonymity
– Allow for users to connect to other users with similar interests
peer2peer
Q/A
1?
2?
3?