Index in P2P system: maps information to peer location

(location = IP address & port number)

Peer-to-Peer Networks: Napster

Napster history: the rise

• January 1999: Napster version 1.0
• May 1999: company founded
• September 1999: first lawsuits
• 2000: 80 million users

Napster history: the fall

• Mid 2001: out of business due to lawsuits
• Mid 2001: dozens of P2P alternatives that were harder to touch, though these have gradually been constrained
• 2003: growth of pay services like iTunes

Napster history: the resurrection

• 2003: Napster reconstituted as a pay service
• 2006: still lots of file sharing going on
  
  
  

Napster Technology: Directory Service   

• User installing the software
  • Download the client program
  • Register name, password, local directory, etc.
• Client contacts Napster (via TCP)
  • Provides a list of music files it will share
  • … and Napster’s central server updates the directory
• Client searches on a title or performer
  • Napster identifies online clients with the file
  • … and provides IP addresses
• Client requests the file from the chosen supplier
  • Supplier transmits the file to the client
  • Both client and supplier report status to Napster

Napster Technology: Properties

• Server’s directory continually updated
  • Always know what music is currently available
  • Point of vulnerability for legal action
• Peer-to-peer file transfer
  • No load on the server
  • Plausible deniability for legal action (but not enough)
• Proprietary protocol
  • Login, search, upload, download, and status operations
  • No security: cleartext passwords and other vulnerability
• Bandwidth issues
• Suppliers ranked by apparent bandwidth & response time

Napster: Limitations of Central Directory

• Single point of failure
• Performance bottleneck
• Copyright infringement

• So, later P2P systems were more distributed

P2P: centralized index

original “Napster” design

1. when peer connects, it informs central server:
   
   – IP address
   – content
2. Alice queries for “Hey Jude”
3. Alice requests file from Bob

• single point of failure
• performance bottleneck
• copyright infringement: “target” of lawsuit is obvious