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peer2peer A closer look

stephen_andrada

casey_cooper

reed_kenyon

peer2peer Outline

•Networks•Issues

•General

•Future

GnutellaFastTrack

Pure P2P

Hybrid P2P

NapstereDonkeyBitTorrent

Security Legality

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 pay-per-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?