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Protocols for the Wireless Paranoid

Protocols for the Wireless Paranoid. Nitin Vaidya University of Illinois http://www.crhc.uiuc.edu/wireless Slightly revised version of slides used for a 2005 INFOCOM (Miami) panel on Paranoid Protocol Design for Wireless Networks March 16, 2005

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Protocols for the Wireless Paranoid

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  1. Protocols for the Wireless Paranoid Nitin Vaidya University of Illinois http://www.crhc.uiuc.edu/wireless Slightly revised version of slides used for a 2005 INFOCOM (Miami) panel on Paranoid Protocol Design for Wireless Networks March 16, 2005 Other panelists: Jean-Pierre Hubaux (Moderator), Bill Arbaugh,Ed Knightly, Adrian Perrig

  2. Disclaimer If you review my research proposals, ignore everything I say here

  3. Panel’s Premise • Wireless networks needmore paranoid protocolsthan wired networks

  4. Wireless Networks • Greater paranoia may be desirable in wireless networks • Easier to “tap” into • Limited resources  Incentive to cheat  Programmable devices provide means to cheat • But …

  5. What are Paranoid ProtocolsAnyway?

  6. Department of NetLand Security(DNS) Severe Paranoid High Characterized by extreme and irrational distrust Elevated Guarded Low Threat Assessment

  7. Paranoid Design Principles • Everything that can go wrong, will - Murphy’s Law • Protect against everything

  8. Research Community’s Response • Enumerate all possible ways things can go wrong • Separate solution for each of the ills • Not quite the right approach • Proof by Example  3 Mistakes often made

  9. Mistake 1:Assuming Extreme Scenarioas the Common Case Ad hoc network are coming ! Ad hoc networks are coming !!

  10. “Extreme” Ad Hoc NetworkingLarge Isolated Networks No infrastructure C E A B

  11. Why build networks this way, if you don’t have to? Not all networks are for the battlefield !! Extreme Scenario • “Extreme” ad hoc networks: No infrastructure  No certification authority  No DHCP server  Long-lived partitions

  12. Extreme Ad Hoc Networks • Model acceptable when exploring design space for MAC and routing • Assuming same model for “security” can lead tounnecessary complexity

  13. More Likely Ad Hoc NetworksAccess to Infrastructure or Small internet C E A B

  14. More Likely Ad Hoc NetworksAccess to Infrastructure or Small

  15. Mesh node Mesh node Wireless channel Wireless channel More Realistic Multi-Hop WirelessMesh Networks internet Wireless “backbone” B C A

  16. Access Point Wireless channel More Realistic Multi-Hop WirelessHybrid Networks internet Access Point Wireless channel E B C A D

  17. Even Vehicles Can Have Intermittent Infrastructure Access Picture courtesy Prof. Jean-Pierre Hubaux (somewhat modified from Prof. Hubaux’s version)

  18. Multi-Hop Wireless is Here(Summary) • Multi-hop wireless,but “infrastructure” can be accessed selectively • Not all enumerable scenarios are relevant  Design protocols for the likely scenarios

  19. Mistake 2:“In-Band” Solutions • “In-band” solutions Solution tied closely to attack

  20. Mistake 2:“In-Band” Solutions • Example attack: Node refuses to forward packets • In-band solution: Watch each other for the misbehavior P C A B Discard

  21. Out-of-Band SolutionsOften More Practical • Disincentives for not forwarding packets • Misbehavior translates to poor performance  Re-route around “bad” parts of the network Single out-of-band solution can help with manyattacks

  22. Access Point Wireless channel Mistake 2: “In-Band” Solutions • Example Attack: MAC Layer selfish misbehavior for performance gains • In-band solution: Detect whether a node followsprotocol faithfully • Out-of-band solution: Determine whether a node receives unfair share

  23. Out-of-Band Solutions(Summary) • Out-of-band solutions often superior, and easier to implement

  24. Mistake 3Wireless = Wired Equivalent • Many protocols work correctly only when nodes seeidentical wireless channel status

  25. Access Point Wireless channel When C transmits, A and B may see different channel status A B C Mistake 3Wireless = Wired Equivalent • Many protocols work correctly only when nodes seeidentical wireless channel status  Protocols cannot perform as advertised

  26. Mistake 3Wireless = Wired Equivalent • Under realistic channel conditions, some of the attacks also difficult to launch undetected • Example: Certain “wormhole” attacks Ignore such attacks?

  27. Mistake 3(Summary) • Pay attention to the physical layer • Wired equivalent for wireless not always reasonable • Use solutions that do not rely on such assumptionsOut-of-band solutions, removed from the cause, may be less prone

  28. Conclusion • Not everything that can go wrong isworth the cost of protection • Develop small set of solutions for alarge problem space • Know the wireless channel Need to protect wireless networks …but

  29. Conclusion Wireless networks are complex Focus on the real problems, ignore the imaginary

  30. Thanks !nhv@uiuc.edu

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