Slide 1 MANETconf Configuration of Hosts in a

Slide 1 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

Slide 2 Outline n n n n n Background Information Topic Primer System Model Related / Previous Work MANETconf Concept MANETconf Operation Making MANETconf Robust Security Issues Simulations Conclusions

Slide 3 Background Information n 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 323 i Plays Squash, Badminton, Cricket His website at UTD is called “The Dark Dungeon”

Slide 4 Background Information n 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: • • Nesargi’s Advisor Big Robert De Niro fan Toastmaster International Member He “comes in peace and wants to make the world a happy place. ”

Slide 5 MANETs: Primer n Typical Wireless Networks: – Wireless Server Assigns DHCP, IP, DNS, netmask – Data is routed through server – Wireless Server may be Internet gateway

Slide 6 MANETs: Primer n MANET (Mobile Ad Hoc Network): – Group of mobile, wireless nodes working cooperatively and spontaneously – Devoid of fixed infrastructure or central administration

Slide 7 System Model n Without centralized servers, unconfigured nodes joining the MANET must be assigned a unique IP addresses. n Hosts already in the MANET must be responsible for uniquely configuring hosts wishing to join the MANET. n Hosts in the MANET must be responsible for allowing graceful and abrupt host departures.

Slide 8 System Model n In IPv 4, the MANET can use: – 10. 0 – 10. 255 – 172. 16. 0. 0 – 172. 31. 255 – 192. 168. 0. 0 – 192. 168. 255 n Nodes communicate through the exchange of IP packets. n 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.

Slide 9 Related/Previous Work n Zeroconf Working Group: – Attacks similar problem of network configuration with the lack of dedicated servers. n Assigns unique IPs to nodes in: – Single network segments where all nodes can directly communicate. – Multiple segments connected to the same router. n Limits the flexibility of Ad Hoc Networks

Slide 10 Related/Previous Work n PMWRS (Perkins, Malinen, Wakikawa, Royer, Sun): n PMWRS Limitations: – Similar to Zeroconf. – Performs duplicate address detection through multiple rounds of MANETwide flooding. – 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.

Slide 11 Related/Previous Work n Hardware Based Addressing: – Use the “unique” hardware address of a card to help uniquely assign IPs (MAC address in Ethernet Adapters). n 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?

Slide 12 MANETconf Concept n 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. n 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.

Slide 13 MANETconf Operation n 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.

Slide 14 MANETconf Operation n 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.

Slide 15 MANETconf Operation n New Node Joining the MANET (cont’d): – 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.

Slide 16 MANETconf Operation n 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.

Slide 17 MANETconf Operation n 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.

Slide 18 Making MANETconf Robust n 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 d’s 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 A’s IP.

Slide 19 MANETconf Operation n 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 a’s 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.

Slide 20 Making MANETconf Robust n 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 a’s 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 b’s address request will eventually time out and the IP will be flushed from the Allocated_Pending lists.

Slide 21 Making MANETconf Robust n 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.

Slide 22 Making MANETconf Robust n 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.

Slide 23 Making MANETconf Robust n Partition Detection (cont’d): – 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.

Slide 24 Security Issues n 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. n 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. n Authors claim that their proposed solution is only as insecure as other solutions and protocols such as ARP and RARP. n Resolution to the above attacks can be achieved with the use of digital certificates from a trusted Authentication Server.

Slide 25 Simulations n Performed on ns-2 (ver 2. 1 b 6 a) with CMU extensions to support ad hoc networks. n Simulations for related approaches (Zeroconf, etc) are not performed due to their “deterministic latency and number of messages that can be computed theoretically. ” n Simulations do not implement support for handling partitioning.

Slide 26 Simulations n MANET is modelled with moving nodes. Nodes pick a random coordinate, move at a speed of 5 m/s, stop at the destination for 10 s, then repeat the process. n Maximum number of nodes is 40, 50, 60, and 80. n Maximum node density is one node per 0. 02 km 2. n For 40, 60, and 80 node simulations, simulations are started with 25, 35, and 45 preconfigured nodes respectively. n Node arrival times uniformly distributed in the range 0 – 70 s. n Node lifetime varies between 0 -1000 s, 0 -2000 s, and 0 -15000 s. n Graceful departures varied between 75% and 100%. n Underlying routing protocol is DSDV. n No arrivals accepted in the first 200 s to allow nodes to set up routing tables.

Slide 27 Simulations n 75% graceful and 25% abrupt departures. n Most addresses are allocated in under 0. 5 s n 5 s allocation attempts correspond to unanswered initiator requests and are consistent with the numbers set in the initiator_request_timer field. n 10 s allocation attempts correspond to situations where abrupt departure nodes were cleaned up.

Slide 28 Simulations n 100% graceful departures. n Latency is high for some address allocation attempts due to packet loss. n Only the results of the samples that are not dropped are shown. n Time required for address allocation increases with the number of nodes in the network.

Slide 29 Simulations n Broadcast: – – – n Initiator_Request Address_Cleanup Other Flood Messages Multicast: – Messages sent to nodes that fail to respond to Initiator_Request messages. n Unicast: – All communications directed back to the initiator.

Slide 30 Conclusions n MANETconf allows for dynamic allocation of IPs in a Mobile Ad Hoc Network without the need for a centralized server running DHCP. n Proposed solution is tolerant to splits and merges and can tolerate message loss. n Reasonable overhead.

Slide 31 Questions?