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Accountability and Resource Management in Higher Ed P2P

Accountability and Resource Management in Higher Ed P2P. David Molnar, Free Haven Project and ShieldIP, Inc. dmolnar@shieldip.com. 25 Minutes. Show Problems Approaches and Tools Example Applications Why You Should Care! What to Watch – Where Next. P2P Problems.

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Accountability and Resource Management in Higher Ed P2P

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  1. Accountability and Resource Management in Higher Ed P2P David Molnar, Free Haven Project and ShieldIP, Inc. dmolnar@shieldip.com

  2. 25 Minutes • Show Problems • Approaches and Tools • Example Applications • Why You Should Care! • What to Watch – Where Next

  3. P2P Problems • Too much bandwidth! (Napster) • File sharing fills with “garbage” • Intentional – “fake” songs • Unintentional – searching doesn’t work • “Free Riding” • Misbehaving Clients (SETI@Home)

  4. Resource ManagementAccountability • Lesson – P2P won’t 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.

  5. Two Approaches • Micropayments • Reputation Systems

  6. Micropayments • Pay for Play! • Not necessarily “real” money. • Make attack “more trouble than it’s worth.” • Slow down DoS attack • Maybe get something useful on side? • Many many different embodiments • We’ll skip the details; see P2P book chapter.

  7. 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

  8. 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

  9. 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?

  10. 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?

  11. 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 < total amount ever stored • Still researching details

  12. 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

  13. 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”  can’t “meaningfully” affect each other

  14. 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?

  15. 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?

  16. 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?”

  17. Why You Should Care • Designing new P2P systems? • Can’t ignore these issues! • Using existing P2P systems? • Judge between systems. • Manage a network? • Encourage better P2P systems.

  18. Things To Watch • “Supernode” routing (KaZa/Morpheus) • Content-aware routing • Bandwidth-aware routing • Consistent hashing (Chord) • User Interfaces for picking P2P nodes

  19. 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. • O’Reilly OpenP2P.com

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