Accountability and Resource Management in Higher Ed P2P

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Accountability and Resource Management in Higher
Ed P2P

• David Molnar, Free Haven Project
• and ShieldIP, Inc.
• dmolnar_at_shieldip.com

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25 Minutes

• Show Problems
• Approaches and Tools
• Example Applications
• Why You Should Care!
• What to Watch Where Next

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P2P Problems

• Too much bandwidth! (Napster)
• File sharing fills with garbage
• Intentional fake songs
• Unintentional searching doesnt work
• Free Riding
• Misbehaving Clients (SETI_at_Home)

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Resource ManagementAccountability

• Lesson P2P wont save you!
• Cornucopia and Tragedy of the Commons
• Resource Management prevent resources from
  being abused.
• Accountability prevent member from using too
  many resources without giving something back.

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Two Approaches

• Micropayments
• Reputation Systems

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Micropayments

• Pay for Play!
• Not necessarily real money.
• Make attack more trouble than its worth.
• Slow down DoS attack
• Maybe get something useful on side?
• Many many different embodiments
• Well skip the details see P2P book chapter.

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Micropayment Example Postage against Spam

• In real life, Post Office charges money
• Online, e-mail free ? unlimited spam
• Charge postage, limit spam
• Too hard to charge online
• Solve Medium-Hard problems for postage
• Maybe use the solution for something else!
• Dwork Naor Pricing via Processing, Back
  hashcash, Juels Jakobsson Bread Pudding
  Protocols, camram mailing list

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Micropayment Example Protecting SSL Handshake

• SSL Secure Sockets Layer
• Public-key handshake hard for server, but easy
  for client!
• One laptop ? DoS large server
• Solution force laptop to pay for handshake
• Stubblefield Dean Client Puzzles and TLS in
  USENIX 2001

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Micropayment Example MojoNation

• http//www.mojonation.net/
• Buy and sell services with mojo
• swarm download, better content distribution
• Transition period
• Will Mojo ever be worth real money?
• Is Mojo just for load balancing?
• Will users accept micropayments?

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Reputation Systems

• Reputation as Everyday Concept
• Consumer Reports, book reviews, etc.
• Pitfalls of Reputation Online
• Pseudospoofing many identities, one adversary
• Erasing bad reps
• Shilling
• How to Automate Reputation?

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Reputation Example Free Haven

• Free Haven content storage service
• Servers have reputations
• Probationary period store for free
• Server loses content ? loses reputation
• Idea amount lost
• Still researching details

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Slashdot, AIM

• Slashdot moderation system
• Frequent users annotate posts as good/bad
• Site displays aggregate of all votes
• AIM warn/block system
• Buddy harasses you warn em
• Too many times blocked

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Pseudospoofing and Advogato

• Pseudospoofing many identities controlled by
  single adversary
• May shill for each other
• May pretend to attack each other
• Advogato trust metric
• Create trust graph, find maximum flow from
  trust source to user.
• Pseudospoofing nodes have small flow from trust
  source ? cant meaningfully affect each other

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Higher Ed P2P

• Why is Higher Ed special?
• More bandwidth
• Fluid user population (wireless coming)
• Bottleneck bandwidth
• Early adopters on network
• What can P2P do for Higher Ed?

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Example Lecture Video

• Watch lecture video on PC screen
• P2P ? no central video server
• Issue more popular class videos harder to find
  than less popular?
• Issue peers die in middle of serving video?

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Example Course Materials

• Central web page ? P2P access/storage
• Students add course materials easily
• Old final exams, personal notes, links
• Tools - wiki, P2P filesharing naming, P2P
  groupware
• Issues include moderation, DoS, which is the
  real handout?

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Why You Should Care

• Designing new P2P systems?
• Cant ignore these issues!
• Using existing P2P systems?
• Judge between systems.
• Manage a network?
• Encourage better P2P systems.

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Things To Watch

• Supernode routing (KaZa/Morpheus)
• Content-aware routing
• Bandwidth-aware routing
• Consistent hashing (Chord)
• User Interfaces for picking P2P nodes

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Where To Go Next

• P2P-hackers mailing list
• http//zgp.org/mailman/listinfo/p2p-hackers/
• Current technical P2P discussions.
• Free Haven Project
• http//www.freehaven.net/
• All the details I left out, recent work on
  reputations.
• CiteSeer
• http//citeseer.nj.nec.com/cs
• Indexes research papers like no one else.
• OReilly OpenP2P.com