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ADVANCED TOPICS

ADVANCED TOPICS. Shambhu Upadhyaya Computer Science & Eng. University at Buffalo Buffalo, New York 14260. Mesh Networks and Security. What are Wireless Mesh Networks?. Similar to Wi-Fi Networks

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ADVANCED TOPICS

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  1. ADVANCED TOPICS ShambhuUpadhyaya Computer Science & Eng. University at Buffalo Buffalo, New York 14260

  2. Mesh Networks and Security

  3. What are Wireless Mesh Networks? • Similar to Wi-Fi Networks • Instead of multiple wireless hotspots (WHS), WMNs use one WHS and several transit access points (TAP), also called routers • Clients connect to TAPs, which connect wirelessly to the WHS either directly or multi-hopping over other TAPs

  4. WMNs • WMN provides reliability through redundancy • It is a special case of wireless ad hoc networks • Wireless mesh networks can be implemented with various wireless technologies including 802.11 (802.11s), 802.15, 802.16 • Examples • MIT RoofNet (2001) • Quail Ridge WMN (QuRiNet) at Napa Valley, CA (2004) • Also useful in smart grid for automatic meter reading

  5. Advantages/Disadvantages • Advantages • The TAPs themselves are cheaper than WHS • Since TAPs communicate by wireless signals, they do not require cabling to be run to add new TAPs • Allows for rapid deployment of temporary networks • Disadvantages • TAPs are often placed in unprotected locations • Lack of physical security guarantees • Communications are wireless and therefore susceptible to all the vulnerabilities of wireless transmissions

  6. Three Security Challenges Posed by WMNs • Securing the routing mechanism • WMNs rely on multi-hop transmissions over a predominantly wireless network • Routing protocol is very important and a tempting target • Detection of corrupt TAPs • The TAPs are likely to be stored in unprotected locations, so they may be easily accessed by malicious entities and can be corrupted or stolen • Providing fairness • The protocol needs to be designed to distribute bandwidth between the TAPs in a manner fair to the users to prevent bandwidth starvation of devices far from the WHS

  7. Fairness • There are several ways in which bandwidth can be distributed among TAPs • What may be the best solution is to distribute bandwidth proportional to the number of clients using a TAP

  8. Attack Model • Four simple types of attacks possible • The first attack is removal and replacement of the device • easily detected by change of topology • Access the internal state of the device • Modify internal state • Clone TAPs • Other sophisticated attacks possible • Blocking attacks, black hole, sybil, etc.

  9. Access Internal State • This is a passive attack and is difficult to detect • In this attack the attacker need not disconnect the device from WMN • Even the disconnection cannot be detected • The effect of the attack can be reduced by changing the TAP data at regular intervals

  10. Modify Internal State • In this type of attack, the attacker can modify the routing algorithm • This type attack also changes the topology • It can also be detected by WHS

  11. Clone TAP • In this type of attack the attacker is able to create a replica of the TAP and place this in a strategic location in WMN • It also allows the attacker to inject some false data or to disconnect some parts of network • It can damage the routing mechanisms but can be detected

  12. Jamming and Countermeasure • The first diagram shows the attack by the adversary • The second diagram shows the protection measure for this attack after detection

  13. Attacks on Multihop Routing in WMN • Rational attack vs. malicious attack • A rational attack • Does only if misbehaving is beneficial in terms of price, QoS, or resource saving • For instance, force the traffic through a specific TAP in order to monitor the traffic of a given mobile client or region • A malicious attack • Involves partitioning the network or isolating the TAPs • For instance, the routes between WHS and TAPs are artificially increased leading to poor performance

  14. Securing Multihop Routing • Using secure routing protocols to prevent attacks against routing messages • If the state of one or more TAPs is modified, the attack can be detected and the network reconfigured • DoS attacks can be prevented by identifying the source of disturbance and disabling it

  15. Generalized WMNs • Vehicular Networks is special case of WMNs where TAPs are represented by cars and roadside WHS • Involves applications such as reporting events (accidents), cooperative driving, payment services and location based services • Multi-Operator WMNs include several operators and various devices: mobile phones, laptops, base stations and APs

  16. Conclusion • WMNs extend the coverage of WHS in an inexpensive manner • The three fundamental security issues that have to be addressed in WMNs • Detection of corrupt TAPs • Defining and using a secure routing protocol • Defining and implementing a proper fairness metric

  17. Reference • Ben Salem, N.; Hubaux, J-P, "Securing wireless mesh networks ,“ Wireless Communications, IEEE, vol.13, no.2, pp.50,55, April 2006

  18. Energy-Aware Computing

  19. Issues in Sensor Networks • Localization • Synchronization • In-network processing • Data-centric querying • Energy-aware computing

  20. Energy Constraints • Battery-powered devices • Communication is much more energy consuming than computation • Transmitting 1 bit costs as much energy as running 1,000 instructions • Gap is only going to be larger in the future • Load balancing • Coordinated sleeping schedules • Explore correlation in sensing data • Power saving techniques integral to most sensor networks

  21. MAC Protocols for Sensor Networks • Contention-Based: • CSMA protocols (IEEE 802.15.4) • Random access to avoid collisions • IEEE 802.11 type with power saving methods • Scheduling-Based: • Assign transmission schedules (sleep/awake patterns) to each node • Variants of TDMA • Hybrid schemes

  22. MAC Protocol Examples • PAMAS [SR98]: • Power-aware Medium-Access Protocol with Signaling • Contention-based access • Powers off nodes that are not receiving or forwarding packets • Uses a separate signaling channel • S-MAC [YHE02]: • Sensor Medium Access Control protocol • Contention-based access • TRAMA [ROGLA03]: • Traffic-adaptive medium access protocol • Schedule- and contention-based access • Wave scheduling [TYD+04]: • Schedule- and contention-based access

  23. S-MAC • Identifies sources of energy waste [YHE03]: • Collision • Overhearing • Overhead due to control traffic • Idle listening • Trade off latency and fairness for reducing energy consumption • Components of S-MAC: • A periodic sleep and listen pattern for each node • Collision and overhearing avoidance

  24. S-MAC: Sleep and Listen Schedules • Each node has a sleep and listen schedule and maintains a table of schedules of neighboring nodes • Before selecting a schedule, node listens for a period of time: • If it hears a schedule broadcast, then it adopts that schedule and rebroadcasts it after a random delay • Otherwise, it selects a schedule and broadcasts it • If a node receives a different schedule after selecting its schedule, it adopts both schedules • Need significant degree of synchronization

  25. S-MAC: Collision and Overhearing Avoidance • Collision avoidance: • Within a listen phase, senders contending to send messages to same receiver use 802.11 • Overhearing avoidance: • When a node hears an RTS or CTS packet, then it goes to sleep • All neighbors of a sender and the receiver sleep until the current transmission is over

  26. Routing Strategies • Geographic routing: • Greedy routing • Perimeter or face routing • Geographic localization • Attribute-based routing: • Directed diffusion • Rumor routing • Geographic hash tables • Energy-aware routing: • Minimum-energy broadcast • Energy-aware routing to a region

  27. Energy-Aware Routing • Need energy-efficient paths • Notions of energy-efficiency: • Select path with smallest energy consumption • Select paths so that network lifetime is maximized • When network gets disconnected • When one node dies • When area being sensed is not covered any more • Approaches: • Combine geographic routing with energy-awareness • Minimum-energy broadcast

  28. Minimum Energy Broadcast Routing • Given a set of nodes in the plane • Goal: Broadcast from a source to all nodes • In a single step, a node may broadcast within a range by appropriately adjusting transmit power • Energy consumed by a broadcast over range γ is proportional to γα • Problem: Compute the sequence of broadcast steps that consume minimum total energy • Centralized solutions • NP-complete [ZHE02]

  29. Three Greedy Heuristics • In each tree, power for each node proportional to αth exponent of distance to farthest child in tree • Shortest Paths Tree (SPT) [WNE02] • “Node” version of Dijkstra’s SPT algorithm • Minimum Spanning Tree (MST) [WNE02] • Maintains an arborescence rooted at source • Broadcasting Incremental Power (BIP) [WNE02] • In each step, add a node that can be reached with minimum increment in total cost • SPT is Ω(n)-approximate, MST and BIP have approximation ratio of at most 12 [WCLF01]

  30. References • Feng Zhao and Leonidas Guibas, Wireless Sensor Networks: An Information Processing Approach, Morgan Kaufman, 2004 • Jeffrey E. Wieselthier, Gam D. Nguyen, and Anthony Ephremides. 2002. Energy-efficient broadcast and multicast trees in wireless networks. Mob. Netw. Appl. 7, 6 (December 2002)

  31. Advanced Metering Infrastructure (AMI)

  32. A Typical Smart Grid

  33. Advanced Meter Reading • Advanced Metering Infrastructure (AMI) or smart meters (2-way) • Used for revenue accounting • Wireless based • Many proprietary • Moderate range, drive-by reading • Mesh (Zigbee) and WiFi sometimes • About 50Million AMR/AMI installed (USA) • Suggested standard: ANSI C12.18 • Smart meters (at Microgrid level) provide information needed to analyze energy usage and thus allow energy minimization algorithms to be implemented

  34. Prospects for Smart Appliances • Examples: smart refrigerator, smart dryer • Two-way communication via Internet • Logical extension of smart grid/buildings • Technically possible for years but … • Hardware costs high; Installation may be complex; Standards lacking • Forms a SCADA or CPS system • Security and privacy concerns high • Benefits unclear • Futuristic discussion mostly

  35. Smart Metering Communication • Zigbee is ideal for AMI • Can network a no. of sensors and controllers in a household • Possibly in a mesh network • Can operate in one of 3 frequency bands

  36. Potential Concerns • WiFi and Zigbee interference • Can be handled by separating the channels by 30MHz • Security concerns of ad hoc and mesh networks apply • Eavesdropping • Traffic analysis • Replay attacks • Additionally: • Employee mistakes, equipment malfunctions, virus, coordinated attacks from a state or terrorist group • Privacy concerns • Smart meters collect personally identifiable info • Cyber criminals could use them for identity theft

  37. A Privacy Compromise Scenario • Electricity use patterns could lead to disclosure • Could leak info on customers • When they’re at home (sleeping versus watching television) • When at work, or traveling • It might also be possible to discover what types of appliances and devices are present • Increases in power draw could suggest changes in business operations • Impacts • Criminal targeting of home • Business intelligence to competitors

  38. Hacking Attacks and Mitigation • Two-way communication between customers and utility companies means more risk • Two-way meters accessible to both users and enemies (use buggy s/w) • Smart meter is the pain point (may be hacked) • Simulation of a worm injected into a meter shows • how it would spread • how it can be used to cause power grids to surge or shut off • Common vulnerabilities exist, but no powerful devices to implement • Devices do not have cycles to implement strong crypto solutions • Mitigation techniques • Zigbee security (uses hierarchy of keys) • Machine-to-machine strong authentication • Encryption • Data hashing, digital signing, etc. • This is an active research area today

  39. References • Darold Wobschall, University at Buffalo, 2012 • M. Nabeel, J. Zage, S. Kerr, E. Bertino, Cryptographic Key Management for Smart Power Grids, 2012, http://www.cerias.purdue.edu/apps/reports_and_papers/view/4591

  40. Internet of Things (IoT)

  41. What is IoT? • Loosely coupled decentralized system of smart objects • Ubiquitous computing, 100B to be connected to the Internet by 2020 • After the WWW, IoT represents the most potentially disruptive technological revolution • What inspired IoT? • RFID, Short-range wireless communication • Real-time localization • Sensor networks • What does it entail? • Scientific theory • Engineering design • User experience

  42. IoT Curriculum • Universities have started building special curricula • Open University in UK has developed a learning infrastructure for collaborative learning in IoT • Merging of the physical and digital realms (CPS) • Physical objects become true actors on the Internet • Huge increase in the number of internet­connected devices, objects, sensors and actuators • Huge increase in the amount and value of data (Big Data) • Emergence of novel embedded device platforms below the level of personal mobile devices • Novel applications in energy, transport, health, business and daily life • Expectation is that MOOCs may take up the challenge • Companies such as Cisco, IBM, Intel are engaging

  43. Skills Set for IoT • Algorithms • Programming skills • Distribution and collaboration • Ability to develop networked sensing apps • Creative design • Collaborative design • Ethical issues • Privacy and security • Computing in society

  44. Typical Components of IoT • iPod • Nokia, Android cell phones • Nintendo DS, Game Boy Advance • Roomba 500 iRobot • Sirius Satellite Radio Receivers • Automobiles

  45. IoT Protocol Details • IEEE 802.15.4 is the standard for low rate WPANs • 802.15.4 handles the physical and MAC layer but not upper layers • Can be used with 6LoWPAN and standard IP protocols to build a wireless embedded Internet • 6LoWPAN is the low power IPv6 version developed for small devices

  46. Internet of Nano Things

  47. Security Challenges in IoT • Cryptographic security • Traditional tools may not be suitable due to limited processor speed and memory • Key management • Manual key management may not scale • Limited user interfaces will make security deployment difficult • Credentialing • Credentialing users and devices required • may not scale due to the sheer size of the nework • Identity management • A devise identity may need to be mapped to groups of users • Usability is also an issue • Limited user interface • Privacy • Sensitive information on health front • “network guards” may be needed

  48. References • http://prezi.com/aordc8uod3rj/internet-of-things-presentation/ • IEEE Computer, February 2013 • I. Akyildiz and J. Jornet, The Internet of Nano-Things, IEEE Wireless Communications, 2010

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