MANETconf: Configuration of Hosts in a Mobile Ad Hoc Network

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MANETconf Configuration of Hosts in a Mobile Ad
Hoc Network

• Authors Sanket Nesargi Ravi Prakash
• Originally Published IEEE INFOCOM 02,
  New York, June 2002
• Presented By Michael Pincott
• Date July 1, 2003

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Outline

• Background Information
• Topic Primer
• System Model
• Related / Previous Work
• MANETconf Concept
• MANETconf Operation
• Making MANETconf Robust
• Security Issues
• Simulations
• Conclusions

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Background Information

• Sanket Nesargi
• Received M.S. and Ph.D. in CS at University of
  Texas at Dallas
• Worked at Nortel for a few years
• Researches
• Mobile Computing/Wireless Networks
• Network Service Protocols
• Protocol Design Frameworks
• Security
• Transport/Network Layers in Fixed and Wireless
  Networks
• Group Communication
• Sensor Networks
• Peer-to-Peer Systems
• Bioinformatics
• Personals
• Moving from Hair Metal into Pink Floyd, Led
  Zeppelin, Rainbow, Deep Purple
• Rides a Kawasaki Ninja ZX 6 motorcycle
• Loves his BMW 323i

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Background Information

• Ravi Prakash
• Received Ph.D. in CS at The Ohio State University
  in 1996
• Researches
• Mobile Computing
• Location Management
• Mobile-TCP
• Cell Planning
• Channel Allocation
• Checkpointing and Recovery
• Causally and Totally Ordered Message Delivery
• Clocks and Dependency Tracking
• Personals
• Nesargis Advisor
• Big Robert De Niro fan
• Toastmaster International Member
• He comes in peace and wants to make the world a
  happy place.

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MANETs Primer

• Typical Wireless Networks
• Wireless Server Assigns DHCP, IP,DNS, netmask
• Data is routed through server
• Wireless Server may be Internet gateway

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MANETs Primer

• MANET (Mobile Ad Hoc Network)
• Group of mobile, wireless nodes working
  cooperatively and spontaneously
• Devoid of fixed infrastructure or central
  administration

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System Model

• Without centralized servers, unconfigured nodes
  joining the MANET must be assigned a unique IP
  addresses.
• Hosts already in the MANET must be responsible
  for uniquely configuring hosts wishing to join
  the MANET.
• Hosts in the MANET must be responsible for
  allowing graceful and abrupt host departures.

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System Model

• In IPv4, the MANET can use
• 10.0.0.0 10.255.255.255
• 172.16.0.0 172.31.255.255
• 192.168.0.0 192.168.255.255
• Nodes communicate through the exchange of IP
  packets.
• Hosts of edges of MANET may not be directly
  reachable. MANET nodes must behave as routers
  and forward packets from the source to the
  destination.

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Related/Previous Work

• Zeroconf Working Group
• Attacks similar problem of network configuration
  with the lack of dedicated servers.
• Assigns unique IPs to nodes in
• Single network segments where all nodes can
  directly communicate.
• Multiple segments connected to the same router.
• Limits the flexibility of Ad Hoc Networks

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Related/Previous Work

• PMWRS (Perkins, Malinen, Wakikawa, Royer, Sun)
• Similar to Zeroconf.
• Performs duplicate address detection through
  multiple rounds of MANET-wide flooding.
• PMWRS Limitations
• Uses AREQ and AREP.
• Tied to underlying routing protocol as it
  specifies the routes to be used by its messages.
• Uses 169.254.. IP block. Routers drop packets!
  This limits hosts ability to route packets after
  configured.
• Network selects a candidate IP for the host
  joining the network. Checks for conflicts by
  polling hosts in the network. Timeout delays and
  retry constants are limiting when the size/shape
  of network is unknown.
• If multiple hosts request an IP concurrently,
  PMWRS may assign two hosts the same IP.
• Much of the 169.254.. address block is reserved
  by IETF for future use.

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Related/Previous Work

• Hardware Based Addressing
• Use the unique hardware address of a card to
  help uniquely assign IPs (MAC address in Ethernet
  Adapters).
• Hardware Based Addressing Limitations
• MANET nodes not restricted to NICs with unique
  MAC addresses.
• Not all NICs have unique addresses.
• Some devices allow for the reprogramming of the
  MAC address.
• Nodes can be easily determined by tracking the
  MAC. Security?

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MANETconf Concept

• Assign unique IP addresses to hosts despite
  dynamic topology by employing a mutual exclusion
  algorithm.
• A node proposes an IP address for an incoming
  host.
• If proposed IP is accepted by all other hosts,
  the incoming host is assigned that IP.
• Proposed solution is a modified version of the
  Ricart-Agrawala algorithm.
• RA Algorithm modification include the ability to
  be flexible to changing network topology and a
  changing number of users in the network.
• RAs inflexibility for topology changes is the
  motivation for MANETconf.

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MANETconf Operation

• MANET Initialization
• Requestor broadcasts its Neighbor_Query message
  and starts its Neighbor_reply_timer.
• Very first requestor will not receive any
  replied.
• When timer expires, the requestor will try again
  and if there is still no response it assumes it
  is the first node in the MANET.

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MANETconf Operation

• New Node Joining the MANET
• Node i wishes to join the network. Node j is
  currently the only node in the network.
• i broadcasts the Neighbor_Query message.
• j responds before the timer expires.
• i selects j as its initiator and ignores any
  other Neighbor_Replies it may receive.
• i sends j a Requester_Request message.

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MANETconf Operation

• New Node Joining the MANET (contd)
• j polls other nodes in the network asking if IP x
  is available for use. Other nodes check their
  Allocated IP and Allocated_pending lists.
• If all responses to j are affirmative, j
• Assigns IP x to node i.
• Adds IP x to its Allocated IP list.
• Floods this information throughout the MANET so
  other hosts can also transfer IP x to their
  Allocated IP lists.
• If at least one host responses with a negative,
  the entire process is repeated with a new IP
  (x).
• Process is repeated until node i is assigned an
  IP or the initiator_request_retry number is
  exceeded. j then notifies i with a failure
  message stating that no resources are available.

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MANETconf Operation

• Concurrent Address Initiation
• Nodes a and e wishes to concurrently join the
  network.
• If the two initiators (b and d) chose unique IPs
  for a and e, there is no conflict.
• If initiators b and d happen to chose the same IP
  for a and e, the initiators IP will be used to
  set priority. The higher priority initiator will
  receive the affirmative ack and the lower
  priority initiator will receive the negative ack.
  

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MANETconf Operation

• Graceful Departure of Node
• Node i wishes to depart the network and
  relinquish its IP before leaving the network.
• i broadcasts the Address_Cleanup message.
• All nodes in the network remove the used IP from
  their Allocated IP list.

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Making MANETconf Robust

• Abrupt or Ungraceful Node Departure
• Node a crashes or ungracefully leaves the
  network.
• Node e wishes to join the network. It selects
  node d as its initiator.
• During node ds initialization process, it sends
  Initiator_Request messages to all the IPs in its
  Allocated IP list.
• Node a will fail to respond to the
  Initiator_Request message.
• Node d then sends an individual Initiator_Request
  message to just node a. Node d will wait until
  its request_reply_timer expires again. It will
  retry again based on the threshold set by
  request_reply_retry.
• With no response from node a, node d sends an
  Address_Cleanup message throughout the MANET to
  release node As IP.

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MANETconf Operation

• Requestor Migration
• Node a wishes to join the network. It selects b
  as its initiator.
• Node a migrates and is unable to communicate with
  b. Node a now chooses c as its initiator.
• Node a informs c of its previous attempt to
  request an IP from b.
• Node c sends node b a message informing b of node
  as migration.
• Node b still queries for an IP for node a. When
  node b arrives at a valid IP for node a, the
  result is sent to node c and node c initiates
  node a.

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Making MANETconf Robust

• Initiator Crash
• Node a wishes to join the network. It selects b
  as its initiator.
• In the middle of the configuration process, node
  b crashes.
• Eventually node as Address_allocation_timer will
  timeout. Node a will then perform another
  Neighbor_query and select a new initiator if one
  can be reached.
• Any other nodes that reserved an IP from node bs
  address request will eventually time out and the
  IP will be flushed from the Allocated_Pending
  lists.

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Making MANETconf Robust

• Network Splits
• The link between nodes c and d fails. The
  network splits into two networks.
• All nodes in one partition can assume that the
  nodes in the other partition have departed
  ungracefully and cleaned up accordingly.

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Making MANETconf Robust

• Partition Detection
• During a network split, what prevents an entering
  node on one partition from assuming the IP of a
  node on a second partition?
• Partitions keep two identifiers lowest
  partition IP address and UUID.
• One partition has the node with the lowest IP
  address. Nodes in this parent partition clean up
  the addresses from the second partition.
• Clean up is also performed in the second
  partition if a node requests an IP address. As
  the lowest IP in the parent node are
  unobtainable, nodes in the second partition
  determine what IP address is the lowest number.
  This lowest IP address node then floods the
  partition and all nodes in that partition then
  know which node is the partition identifier.

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Making MANETconf Robust

• Partition Detection (contd)
• If no IP address assignment is initiated on the
  second partition, a clean up is never triggered
  and the split is not detected.
• In this case, if the lowest IP in tables become
  unreachable after a number of retries a cleanup
  can be initiated.
• Methods work even if network is partitioned into
  multiple partitions.

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Security Issues

• Susceptible to DOS attacks
• A rogue node could act as an initiator and
  effectively allocate all free IPs to phantom
  nodes and prevent valid nodes from joining the
  network.
• The rogue node can also respond to requests on
  behalf of the phantoms to prevent clean ups.
• Susceptible to Malicious Clean up Messages
• A rogue node could clean up the IPs of valid
  nodes and disconnect them from the network. If
  this happens to an initiator, duplicate IPs could
  exist.
• Authors claim that their proposed solution is
  only as insecure as other solutions and protocols
  such as ARP and RARP.
• Resolution to the above attacks can be achieved
  with the use of digital certificates from a
  trusted Authentication Server.

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Simulations

• Performed on ns-2 (ver2.1b6a) with CMU extensions
  to support ad hoc networks.
• Simulations for related approaches (Zeroconf,
  etc) are not performed due to their
  deterministic latency and number of messages
  that can be computed theoretically.
• Simulations do not implement support for handling
  partitioning.

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Simulations

• MANET is modelled with moving nodes. Nodes pick
  a random coordinate, move at a speed of 5 m/s,
  stop at the destination for 10s, then repeat the
  process.
• Maximum number of nodes is 40, 50, 60, and 80.
• Maximum node density is one node per 0.02km2.
• For 40, 60, and 80 node simulations, simulations
  are started with 25, 35, and 45 pre-configured
  nodes respectively.
• Node arrival times uniformly distributed in the
  range 0 70s.
• Node lifetime varies between 0-1000s, 0-2000s,
  and 0-15000s.
• Graceful departures varied between 75 and 100.
• Underlying routing protocol is DSDV.
• No arrivals accepted in the first 200s to allow
  nodes to set up routing tables.

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Simulations

• 75 graceful and 25 abrupt departures.
• Most addresses are allocated in under 0.5s
• 5s allocation attempts correspond to unanswered
  initiator requests and are consistent with the
  numbers set in the initiator_request_timer field.
• 10s allocation attempts correspond to situations
  where abrupt departure nodes were cleaned up.

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Simulations

• 100 graceful departures.
• Latency is high for some address allocation
  attempts due to packet loss.
• Only the results of the samples that are not
  dropped are shown.
• Time required for address allocation increases
  with the number of nodes in the network.

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Simulations

• Broadcast
• Initiator_Request
• Address_Cleanup
• Other Flood Messages
• Multicast
• Messages sent to nodes that fail to respond to
  Initiator_Request messages.
• Unicast
• All communications directed back to the
  initiator.

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Conclusions

• MANETconf allows for dynamic allocation of IPs in
  a Mobile Ad Hoc Network without the need for a
  centralized server running DHCP.
• Proposed solution is tolerant to splits and
  merges and can tolerate message loss.
• Reasonable overhead.

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Questions?