The Start of Digital Anarchy

• Shawn Fanning (19-yr-old student nicknamed Napster) developed the original Napster application and service in January 1999 while a freshman at Northeastern University

– Share MP3 files with peers around the world• Next version: launched in May 1999, by Shawn Fanning (19-yr-old

student nicknamed Napster) and Sean Parker (20)• Allowed Users to MP3 Files - compression format, good quality but

1/12th original size– Napster.com: p2p MP3 exchange service

• November 2000 – Napster has 38 Million members• 40 million users in first 18 months• At peak,70 million users• 1.57 million simultaneous users

What is Napster Indeed?

• Napster is sometimes referred to as a p2p network– This is not quite true

• Napster ran a central server– You connected to that server and announced what files you

had to share.

• Every search was conducted on the dataset assembled at the central server

• Connections to download files where done between peer machines only!

Concept of Napster• Napster used centralized servers to keep a catalog of

available files

1. User sends out requestNapster searches central database

Search request

2. The central server sends back a list of available files for download

Search response

Napsterserver

useruser

useruser

3. Requesting user downloads the file directly from another Napster user computer

Download from user

Importance of Napster

• The P2P revolution is started.

• Central indexing and searching service

• File downloading in a peer-to-peer point-to-point manner.

Napster user B(Client + Server)

Napster indexfile-@IP Association

Napster user A(Client + Server)

How Napster used to work• It is first necessary to download and install Napster software and to

sign up for a free account at Napster• By clicking the Napster icon, a connection is established with Napster

Web site, where the name of the music searched can be entered in a search window

• The Napster software tracks all users who are online at that particular time and provides access to tracks stored on users' hard drives

• When the song requested is found, Napster establishes a connection between the two computers so that it could be downloaded

Four steps:

• Connect to Napster server

• Upload your list of files (push) to server.

• Give server keywords to search the full list with.

• Select “best” of correct answers. (pings)

Directory Server

User User

User User

Description of the ArchitectureDescription of the ArchitectureA central directory server maintainindex on the metadata of all the files in the network. The metadata might includefile names, creation dates, and copyright information . The server also maintain a table of user connection information including user’s IP address and line speed. A file query is sent to the server first. A query consists of a list of desired words.

•When the server receives a query, it searches for matches in its index•The query results including a list of users who hold the file are sent back to the user who initiated the query•The user then opens a direct connection with the peer that has the requested file for downloading

Napster

• A way to share music files with others

• Users upload their list of files to Napster server

• You send queries to Napster server for files of interest– Keyword search (artist, song,

album, bitrate, etc.)

• Napster server replies with IP address of users with matching files

• You connect directly to user A to download file

Overview of the P2P

File Sharing Solutions

Client-Server File Sharing

• Server(s) perform all file sharing tasks– All files stored on server(s)

– All queries regarding file availability addressed by server(s)

– All files transmitted from server(s)

• Therefore, server(s) constrain performance– Can only hold as many files fit in server storage

– Query response time dictated by server speed

– Files transmitted over server network connection with limited capacity

Client-Server File SharingThe MP3.com Architecture

MP3.com

Machine A1. Have any

Metallica songs?

3. Please send one

2. Yes

4. Here it is

Note: A few years ago, a band called Metallica sued the file sharing service Napster for allowing illegal music exchange over it’s network.

Peer-to-Peer File Sharing

• At least some tasks are distributed among peers:– Files stored on and transmitted from peer hosts– Queries regarding file availability addressed by peer

hosts• Distributed tasks are not limited by server performance

– Network can hold as much as can be stored on all peers– Transmission costs shared by all peers– Each peer contributes to responding to queries

• For example, – Napster distributed file storage and transmission– File availability was centralized

Peer-to-Peer File SharingIn Action

• Interacting Messages– Ping: “Are you there?”: Directed at a Peer– Pong: “Yes, I am here”– Query: “I am looking for 007 posters”– Query Response: “I have the poster. Download

from xxx.xxx.xxx.xxx:xx

• All these messages are forwarded from a Peer to its neighbors

www.napster.comMain Server

File List:UserC song.mp3

UserD another.mp3…..

User A

2. User A searches for song.mp3

User C(Song.mp3)

1. Construct Database• Users connect to Napster Server• Server builds up a list of available songs and locations

User D(Another.mp3)

User B…

3. Server searches database. Finds song on User C’s

machine

4. Server informs User A of the

location of song.mp3

5. User A connects to User C and

downloads song.mp3

Brokered/Hybrid P2P

File Sharing with Napster

Broker MediatedFile Sharing Model

• Users register files with a broker for sharing• use broker to find files to copy

Broker

Bob Carol

Where is “X-File Season 7”?

Carol has it

Copying X-File Season 7

Centralized

• Napster model• Benefits:

– Efficient search

– Limited bandwidth usage

– No per-node state

• Drawbacks:– Central point of failure

– Limited scale

Bob Alice

JaneJudy

Resource DiscoveryResource Discovery

Advantages and Disadvantages of Centralized Indexing

• Advantages:– Locates files quickly and efficiently (more effective)

– Searches are as comprehensive as possible

– All users must registered to be on the network• Access is controlled

• Disadvantages:– Vulnerable to censorship and technical failure

• System has single points of entry; one fails could bring whole system down

– Popular data become less accessible because of the load of the requests on a central server

– Central index might be out of data because the central server’s database is only refreshed periodically

Resource DiscoveryResource Discovery

napster.com

users

File list is uploaded

1.

A Simple Example

napster.com

user

Requestand

results

User requests search at server.

2.

A Simple Example

napster.com

user

pings pings

User pings hosts that apparently have data.

Looks for best transfer rate.

3.

A Simple Example

A Simple Example

napster.com

user

Retrievesfile

User retrieves file

4.

Summary of the Features

• Central Napster server– Can ensure correct results– Bottleneck for scalability– Single point of failure– Susceptible to denial of service

• Malicious users• Lawsuits, legislation

• Search is centralized• File transfer is direct (peer-to-peer)

Screenshots – Napster Searching …

Screenshots – Napster Downloading ….

Benefits and Drawbacks of the Napster Model

• Benefits:– Efficient search

– Limited bandwidth usage

– No per-node state

• Drawbacks:– Central point of failure

– Limited scale

Bob Alice

JaneJudy

Traffic Generated by Napster• 3/00: 25% UWisc traffic Napster

• 2000: est. 60M users

• 7/01: # simultaneous online users:• Napster 160K

• Gnutella: 40K

• Morpheus: 300K

• Approximately 10,000 music files were shared per second using Napster, and every second more than 100 users attempted to connect to the system and there will be 75 million Napster users by the end of 2000

• A “disruptive” application/technology?…

Reported Bandwidth of Napster

End of Napster

• 12/99: first lawsuit• April 2000 – Metallica starts law suit – Huge and long court

case • July 2001 – Napster ordered offline, June 2002 bankrupt

• 2/01: US Circuit Court of Appeals: Napster knew users violating copyright laws

• After the Recording Industry Association of America sued Napster for copyright infringements, the court ruled that Napster was indeed violating copyrights and it is shut down

End of Napster (Cont.)

• Napster argued since it was only involved in collecting the information about files available, it was legal.

• Napster never shared any illegal file.

• The courts thought otherwise.

• It was shut down.

• Napster network died without a central machine.

• To enable true piracy, we need a truly distributed system.

Last minute humor

Steve Sack, Minnesota, The Minneapolis Star-Tribune

Epilogue

• 1999: Napster is born

• 2002: Napster is gone…• April 30, 2002:

A new study from WebSense indicates that the number of file-swapping, and peer-to-peer websites, has grown by 535 percent in 2001, despite legal efforts to have them shut down

According to the study findings, the number of p2p websites totals nearly 38,000

http://www.websense.com/company/news/pr/02/042502.cfm

universities notice first mid-01: shut down service; other apps emerge since 00