Survey Presentation

1. Survey Presentation Course: 60-564 Fall 2004 Ataul Bari Instructor: Dr. A. K. Aggarwal

2. Agenda • Introduction • The DSR Protocol • The SADSR Protocol • The SERAN for Security Equipment • Closing Remarks

3. Papers Reviewed • Ghazizadeh, S.; Ilghami, O.; Sirin, E.; Yaman, F.; “Security-aware adaptive dynamic source routing protocol”, Local Computer Networks, 2002. Proceedings. LCN 2002. 27th Annual IEEE Conference on6-8 Nov. 2002 Pages:751 – 760 • Ben-Othman, J.; Xiaoyun Xue; “SERAN: a new protocol to hide an equipment in ad hoc networks”, Computers and Communication, 2003. (ISCC 2003). Proceedings. Eighth IEEE International Symposium on30 June-3 July 2003 Pages:356 - 361 vol.1

4. Introduction • Wireless Networks • Infrastructured Network • Consists of fixed and wired gateways • Fixed base station (Access Point) • Nodes can move geographically • Ad Hoc (or Infrastructureless) Network • All nodes are mobile • Nodes communicate with each other • No centralized entity (base station, Access point) • Nodes are routers

5. Infrastructured Network

6. Ad Hoc Networks

7. Characteristics • Contain a large number of nodes • No pre-existing fixed network infrastructure • Can be deployed rapidly • Nodes can freely move around • Creation and deletion of network links • Dynamically variable topologies • Bandwidth constrained links • Energy constrained operation

8. The MANET Model • Nodes have fixed IDs (e.g. IP addresses) • Wireless communication devices • Nodes are powered with lightweight batteries that have limited life • Nodes have equal capability • Identical communication devices. • Nodes connectivity is not transitive

9. Routing in MANET • Challenging • Unpredictable node mobility • Dynamic topology variation • Nature of wireless media • Types • Flat • Hierarchical • Geo-assisted • Proactive and Reactive Protocols

10. Routing Protocols

11. Security in Ad Hoc Networks • Always a weak Point • Inherent quality of wireless media • Mobility of the nodes • Lack of centralized entity • Security Requirements • Availability, Confidentiality, Integrity, Authentication and Non-Repudiation • Threats • DoS, Impersonation, Byzantine Failure, Disclosure and Poor Physical Protection

12. The SADSR Protocol • Security-Aware Adaptive Dynamic Source Routing Protocol • Basic Idea • Non-malicious node detects malicious nodes • Non-malicious node Isolates malicious nodes • Goal is to Secure DSR Protocol

13. The DSR Protocol • Dynamic Source Routing Protocol • Reactive (on-demand) • Source-Routed • Each node maintains route caches containing the source routes • Updates it whenever it learns about new routes • two major phases • Route discovery • Route maintenance

14. Route Discovery Contd.. • On-Demand • Check Route Cache • Initiates route discovery process • Broadcast a RREQ packet • Includes Source & Destination Address • Includes an unique ID • May be replied by intermediate nodes • May be replied by destination nodes

15. Route Discovery in DSR Ref: Padmini Misra; “Routing Protocols for Ad Hoc Mobile Wireless Networks “ http://www.cse.ohio-state.edu/~jain/cis788-99/ftp/adhoc_routing/, 1999

16. Route Maintenance • Route Error Packet • Fatal transmission problem at its data link layer • Removes that hop from its route cache • All routes included that particular hop are truncated • Acknowledgment packets • Verify the correct operation of the route links

17. The SADSR • Secure DSR protocol by enhancing it • Non-malicious nodes • Detect malicious node • Isolate malicious node • Uses digital signatures to authenticate • Asymmetric cryptography • Keeps • Multiple routes for each destination • A local trust value for each node in the network • Each path is assigned with a trust value

18. The Attackers • External attackers • Inject erroneous routing information • Replay previous routing messages • Modify the valid routing information • Internal attackers • Trusted at some point of time • Not committed to their promises anymore • Compromised by external attackers • More difficult to detect • Isolate affected nodes • Pass traffic through special routes

19. Assumptions • Both External and Internal attackers exists • Malicious nodes are relatively small • All the connections are bidirectional • public key crypto is used • A secure CA in place • All nodes know the public key of CA, • Certificate issued on off line basis • Certificate bounds a nodes IP with its public key • The certificate obtained from CA never expires

20. The SADSR Protocol • Three different stages • Certificate Acquisition • Multi-path Route Discovery • Routing

21. Certificate Acquisition • Nodes obtain a certificate from CA • Issued in an off-line process • Certificates remain valid for entire lifetime • Security problem ? • Networks is set up for a certain time only • Certificate of node v • Nodes get public key of CA,

22. Multi-path Route Discovery • Initiation of Route discovery process • Generate RREQ message • Sign M • Appends, at the end of M, • Encrypted hash value of M, • Its certificate, • Broadcast M

23. Multi-path Route Discovery Contd.. • Intermediate node • Checks if RREQ not too old • Verifies eachsignature with a probability p • Ensures its own signature is not in the sequence • Count is less then [(Max. No. of route, m)/2] • First RREQ msg. from a neighbor for same route • Signs it message • Re broadcast the message • Entries are discarded after a predefined time,

24. Multi-path Route Discovery Contd.. • Destination node • Sets up a timer for the source node, S • Begin to reply • Replies all RREQ messages up to the number m • Non node-disjoint paths • Use 50% probability to reply • To ensure enough route in case of very few neighbor • Generate RREP message, • Signs M, Unicast back to S, usingsame path of RREQ • Intermediate nodes checks signature, signs, forwards • Rest of RREQs are dropped after time

25. Routing – Basic Idea • Nodes locally calculate and keep trust value (TV) of the other nodes • Based on the observations it has made so far • The trust values of the nodes in a path • Increase every time v successfully sends a message through that path, • Decrease if a message is lost or tampered with • Possible as ACK sent through the same path • TV of a path is the product of TVs of its nodes • For routing, paths with higher TV are preferred

26. Assignment of Trust Value • Each source node keeps track of • The paths through which it has sent packets • If it has received the acknowledgement through that path for the corresponding message • Uses two counters for each v in a path,and • The trustworthiness of v, • Trustworthiness of a path =

27. Sending Data Packets • For sending a data packet, source node • Chose a path randomly fromavailable paths • s are likely to know m paths for d • Chance of a path to be chosen is proportional to its trust value • Appends a sequence number with the data packet • Appends the chosen path with the data packet • Signs the packet • Sends through the chosen path

28. Sending Data Packets Cont’d… • Intermediate nodes • Verify the signature of s with a probability p • Then forward the packet • Destination node • If data packet received through path, • Generate an acknowledgement • Signs M • Sends M to s through the same path, P • Intermediate nodes verify signature, forward

29. Updating Trust Values • The source node s maintains a table • of sequence numbers of packets sent • the path used and • a time stamp for time units • Receives a valid ACK • Awards each node on that path • Updates entries for each node on that path • Not -Receives a valid ACK after time • Assumes that the packet is lost • Punish each node on that path • Updates entries for each node on that path

30. Intermediate Link Failure • fails to communicate with • Generate a R.E.M. • Signs it • Sends it to s • The source node s, after receiving the M • Locate and eliminate all path containing the link

31. Security Analysis • The possible attacks on DSR protocol • Attacks on Route Discovery • Attacks on Routing • Fabrication of Route Error Messages • Denial of Service Attacks

32. Attacks on Route Discovery • Modification of source routes • content is changed? • Detected by signature verification • Some or all node info dropped? • No ACK can be reached to S • RREP modified? • Not reached S or discarded there • Route cache poisoning • Only the destination send back RREP • No snooping for intermediate nodes • Not participating in route discovery • Passive maliciousness, nothing can do

33. Attacks on Routing • In a Data Packet, may Modify • Data • Signature verification fails, No ACK • Routes • Not reach destination, No ACK • Dropping the Packets • Dropped packet, no ACK • Gradual isolation

34. False Route Error Msg. And DoS • Fabrication of Route Error Messages • Node may lie that a link is broken • Intermediate node do not snoop and update • Denial of Service Attacks • Sending RREQs with Fake IDs • Node broadcast may RREQ after spoofing IP • intermediate nodes will caught and get rid of some • Rest will be caught at the destination, no RREP • Still a successful attack can be made • Sending RREQs to a Fake Destination • All intermediate nodes will sign and rebroadcast • Currently nothing, but may be extended to keep TV for each S

35. Experimental Results

36. Experimental Results

37. The SERAN • Security Equipment protocol in Routing in Ad hoc Networks • A node is given ability • Use the ad hoc network but not provide resources • Hide itself from the network • Possible application • Conserving energy for critical node • Isolate congested node

38. Basic Idea • Neighbouring nodes know each others at the MAC layer • The protected node, communicate with a neighbor • A new layer, SERAN, between the IP and the transport layer

39. Basic Idea Cont’d… • Node needs an IP address to communicate with others • Dynamic IP address • Fixed IP addresses -> Normal node • No IP addresses -> Invisible node • Use of “Smart Cards” • Implementing DHCP in Smart Cards • Every time there is a communication • The smart card assigns a IP address to • Discards it after that session ended • Next time, assigns a different IP address

40. The Smart Card Ref: http://www.acs.com.hk/smartcardoverview.asp

41. The Communication in SEARAN • Whenever there is an outgoing packet • Gets an IP address from the smart cards, pass the packet • After passing through the network layer, the address is discarded • the packet is uni-cast to including only the destination address in the SERAN header • The SERAN layer is capable of recognizing and sending the message to the destination. • The SERAN header includes the source MAC address to distinguish the real source.

42. The Communication in SEARAN • Incoming packet in the MAC layer, the card checks • The header of the packet to see if the packet’s destination MAC address is its own • If the packet contains the broadcast address (255.255.255.255). • If any of these is true, then get a temporary IP address from the card and pass the packet to the IP layer. • The smart card is capable of decoding the header of the packets.

43. Evaluation of

44. Improvement

45. Advantages and Disadvantages • Advantages • Can keep a node secret • Protected node saves its energy • Protected node can send and receive rapidly • avoid“overflow routing table”, “sleep deprivation” • Disadvantages • Bad influence for the global routing • May reduce the number of multi-routes • Selection of still remains as an issue

46. Conclusions • Security is a weak point in ad hoc networks • The SADSR protocol is proposed to secure an existing protocol called DSR • Tests show that SADSR copes well in presence of malicious nodes • SERAN may be used to hide security equipment in ad hoc network • First known approach using smart card • Looking forward to a secure ad hoc network