Wireless Ad hoc Sensor Networks WASN Motivation

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Wireless Ad hoc Sensor Networks(WASN)--
Motivation --

• Shaikh, Faisal Karim
• PhD Assistant
• DEEDS, Informatik
• TU Darmstadt, Germany
• fkarim_at_deeds.informatik.tu-darmstadt.de

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Agenda

• Wireless Networks
• Ad hoc Networks
• Ad hoc Wireless Sensor Networks (AWSN)
• Paper Presentation
• Comments
• Future work
• QA

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Wireless Networks

• Need Access computing and communication
  services, on the move
• Infrastructure-based Networks
• traditional cellular systems (base station
  infrastructure)
• Wireless LANs
• Infrared (IrDA) or radio links (Wavelan)
• very flexible within the reception area
• low bandwidth compared to wired networks (1-10
  Mbit/s)

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Infrastructure-based wireless networks

• What if
• No infrastructure is available? E.g., in
  disaster areas
• It is too expensive/inconvenient to set up?
  E.g., in remote,
• large construction sites
• There is no time to set it up? E.g., in
  military operations

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Solution (Wireless) ad hoc networks

• Try to construct a network without
  infrastructure, using networking abilities of the
  participants
• This is an ad hoc network a network constructed
  for a special purpose
• Definition of the term Ad Hoc Network
• Mobile ad hoc network (MANET), or simply ad
  hoc network, comprises nodes that freely and
  dynamically self-organize into arbitrary and
  temporary network topology without any
  infrastructure support. (Chlamtac, Conti, and
  Liu, 2003)
• Simplest example Laptops in a conference room
  a single-hop ad hoc network

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Problems/challenges for ad hoc networks

• Without a central infrastructure, things become
  much more difficult
• Problems are due to
• Lack of central entity for organization available
  
• Limited range of wireless communication
• Mobility of participants

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No central entity ! self-organization

• Self-organization
• Pertains to (among others)
• Medium access control
• Finding a route

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Limited range ! multi-hopping

• For many scenarios, communication with peers
  outside immediate communication range is required
• Direct communication limited because of distance,
  obstacles,
• Solution multi-hop network

?
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Mobility !

• Single hop wireless connectivity to the wired
  world
• Space divided into cells
• A base station is responsible to communicate with
  hosts in its cell
• Mobile hosts can change cells while communicating
• Hand-off occurs when a mobile host starts
  communicating via a new base station

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Mobility !

• In MANET
• Host movement frequent
• Topology change frequent
• Complicated by scale
• Large number of such nodes difficult to support
• No cellular infrastructure.
• Multi-hop wireless links.
• Data must be routed via intermediate nodes.

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Wireless sensor networks

• Participants in the previous examples were
  devices close to a human user, interacting with
  humans
• Alternative concept
• focus on interacting with environment
• Network is embedded in environment
• Nodes in the network are equipped with sensing
  and actuation to measure/influence environment
• Nodes process information and communicate it
  wirelessly
• ! Wireless sensor networks (WSN)
• Or Wireless sensor actuator networks (WSAN)

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WSN application examples

• Disaster relief operations
• Drop sensor nodes from an aircraft over a
  wildfire
• Each node measures temperature
• Derive a temperature map
• Biodiversity mapping
• Use sensor nodes to observe wildlife
• Intelligent buildings (or bridges)
• Reduce energy wastage by proper humidity,
  ventilation, air conditioning
• Needs measurements about room occupancy,
  temperature, air flow,
• Monitor mechanical stress after earthquakes

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Roles of participants in WSN

• Sources of data Measure data, report them
  somewhere
• Typically equip with different kinds of actual
  sensors
• Sinks of data Interested in receiving data from
  WSN
• May be part of the WSN or external entity, PDA,
  gateway,
• Actuators Control some device based on data,
  usually also a sink

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MANET vs. WSN
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Conclusion

• MANETs and WSNs are challenging and promising
  system concepts
• Many similarities, many differences
• Both require new types of architectures
  protocols compared to traditional
  wired/wireless networks
• In particular, end-to end reliability in WSN is
  required

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Neutralization of Errors and Attacks in Wireless
Ad Hoc NetworksbyClaudio Basile, Zbigniew
Kalbarczyk, Ravi K. IyerDSN 05

• A paper presentation

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Goal

• to propose and evaluate strategies
• to operate correctly in hostile computing
  environments,
• even if some of the nodes have been compromised
  by errors or attacks.

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Contributions

• Notion of inner-circle consistency,
• secure topology service
• a deterministic voting technique
• a statistical voting technique
• fault-tolerant cluster algorithm
• and threshold cryptography
• Design and formal specification of an
  inner-circle framework
• Prototype and evaluation of the inner-circle
  framework with the ns-2
• the neutralization of black hole attacks in AODV
• the neutralization of sensor errors in a target
  detection/localization application.

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System Model

• N of mobile nodes
• A node does not know the complete set N
• Nodes have unique ids and aware of their
  geographic position
• A threshold cryptography scheme is available.
• A dependability level is an integer L 1
• predetermined range (e.g., 1 L 10)
• and associate a secret signing key KL with each
  value of L.
• KL is not disclosed
• nodes obtain their signing key shares from a
  trusted dealer at the systems initialization
• No global synchronization.

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System Model (contd.)

• Nodes may fail by crashing or by becoming
  Byzantine.
• Correct nodes never fail.
• In the absence of failures and node movement
• connected to its neighbors
• wireless channels are timely
• Following assumptions are made by authors about
  adversary
• The cryptographic primitives are secure.
• limited jamming range and cannot disrupt the
  whole network.
• Compromised nodes are not capable of sharing
  their identities/secret keys.

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Overview of Inner-circle Consistency

• Execution Scenario.
• Inner-circle Concept.
• Inner-circle Mechanism.

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Inner-circle Consistency Node Architecture
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3
4

• STS discovers and authenticates bidirectional
  links and provides
• each node with a local topology view.
• STS implementation assumes that local clocks at
  neighboring
• nodes are kept (approximately) synchronized,
• periodic broadcasting of STS messages
• STS message contain list of authenticated
  neighbors
• G. Lowe. Breaking and fixing the
  Needham-Schroeder public key protocol using FDR.
  In Proc. of TACAS, 1996.

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1
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Ad Hoc Node Embodiment.
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Sensor Node Embodiment.
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Fault-Tolerant Cluster Algorithm.

• to generate, from a set P of L observations, an
  estimate TFT
• we exclude from the estimation process only those
  observations that are likely to be
  faulty/malicious

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Example Black Hole Attack in AODV Networks

• Black hole attack is difficult to detect
• Malicious routing messages are injected in the
  network
• A malicious node M (black hole node) advertises
  to other nodes that it has a valid route to a
  destination node D, even though the route is
  spurious, with the intention of intercepting
  packets
• Neutralize malicious routing messages locally, by
  exploiting redundant routing information in the
  network
• Mounting a black hole attack

RREQ(D,3)
N2
N3
RREQ(D,3)
RREP(D,5)
RREP(D,20)
D
S
RREQ(D,3)
RREP(D,5)
RREP(D,5)
RREQ(D,3)
RREQ(D,3)
N4
N1
M
RREP(D,20)
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Black Hole Attack in AODV Networks

• AODV service at a node c sends a RREP message
  ltRREP, route_dst, dseqno, next hopgt
• cs ICV executes a deterministic voting algorithm
• IC node p verifies that cs proposed RREP is
  valid
• Upon L acknowledgement, c send agreed message to
  all its IC nodes
• IC node p updates the local mapping so as to
  include both nodes c and next hop
• if p is cs next hop, then p handles the RREP
  message to its local AODV service.
• Then, the operation continues with node ps

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Simulation study of black hole attack
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Faulty Sensors Case Study

• To improve sensor data accuracy in spite of
  sensor errors
• Detect the presence of a nearby target and to
  estimate the targets position
• Sensor devices interact directly with the
  environment this makes them degrade fairly
  quickly.
• Following sensor fault model is considered
• Stuck at Zero
• Calibration Error
• Signal Interference
• Positioning Error

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Faulty Sensors Case Study

• Node c detects a target and sends lt DIFF,(tc ,
  Ec, uc), next hopgt
• cs IVS executes a statistic voting algorithm
• cs IVS solicit message to cs inner-circle
  nodes.
• IVS at a receiving node p determines whether to
  send ps value tp, Ep, up and, if so, sends a
  value message to c.
• After L value messages, node c fuses the
  available values tc , Ec, uc U tp, Ep, up
  into a single value and sends to its IC nodes a
  propose message.
• Node p verifies the correctness of the included
  fused value and, if the check passes, sends an
  ack message to c.
• After L ack messages, node c sends an agreed
  message.
• If node p is cs next hop, then p sends the
  agreed message to the base station, encapsulating
  it into a directed diffusion message.

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Simulation study of a faulty sensor network.
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Suggestions

• The notion of inner-circle is good but based on
  assumption of high density of powerful middle
  layer nodes which seems to be unrealistic.

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Future Work

• Paper presentation next week

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Questions
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Thanks

• fkarim_at_deeds.informatik.tu-darmstadt.de