Internet DRAFT - draft-ietf-manet-smf-sec-threats


Mobile Ad hoc Networking (MANET)                                   J. Yi
Internet-Draft                                                T. Clausen
Intended status: Informational                  LIX, Ecole Polytechnique
Expires: September 9, 2016                                    U. Herberg
                                                           March 8, 2016

       Security Threats for Simplified Multicast Forwarding (SMF)


   This document analyzes security threats of the Simplified Multicast
   Forwarding (SMF), including the vulnerabilities of duplicate packet
   detection and relay set selection mechanisms.  This document is not
   intended to propose solutions to the threats described.

Status of this Memo

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   This Internet-Draft will expire on September 9, 2016.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  SMF Threats Overview . . . . . . . . . . . . . . . . . . . . .  4
   4.  Threats to Duplicate Packet Detection  . . . . . . . . . . . .  5
     4.1.  Common Threats to Duplicate Packet Detection Mechanisms  .  5
       4.1.1.  Replay Attack  . . . . . . . . . . . . . . . . . . . .  6
     4.2.  Threats to Identification-based Duplicate Packet
           Detection  . . . . . . . . . . . . . . . . . . . . . . . .  7
       4.2.1.  Pre-activation Attacks (Pre-Play)  . . . . . . . . . .  7
       4.2.2.  De-activation Attacks (Sequence Number wrangling)  . .  8
     4.3.  Threats to Hash-based Duplicate Packet Detection . . . . .  8
       4.3.1.  Attack on Hash-Assistant Value . . . . . . . . . . . .  9
   5.  Threats to Relay Set Selection . . . . . . . . . . . . . . . .  9
     5.1.  Relay Set Selection Common Threats . . . . . . . . . . . . 10
     5.2.  Threats to E-CDS Algorithm . . . . . . . . . . . . . . . . 10
       5.2.1.  Link Spoofing  . . . . . . . . . . . . . . . . . . . . 10
       5.2.2.  Identity Spoofing  . . . . . . . . . . . . . . . . . . 11
     5.3.  Threats to S-MPR Algorithm . . . . . . . . . . . . . . . . 11
     5.4.  Threats to MPR-CDS Algorithm . . . . . . . . . . . . . . . 11
   6.  Future Work  . . . . . . . . . . . . . . . . . . . . . . . . . 12
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   9.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 13
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 13
     10.2. Informative References . . . . . . . . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14

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1.  Introduction

   This document analyzes security threats to the Simplified Multicast
   Forwarding (SMF) mechanism [RFC6621].  SMF aims at providing basic
   Internet Protocol (IP) multicast forwarding, in a way that is
   suitable for limited wireless mesh and Mobile Ad hoc NETworks
   (MANET).  SMF is constituted of two major functional components:
   Duplicate Packet Detection and Relay Set Selection.

   SMF is typically used in decentralized wireless environments, and is
   potentially exposed to different kinds of attacks and
   misconfigurations.  Some of the threats are of particular
   significance as compared to wired networks.  In [RFC6621], SMF does
   not define any explicit security measures for protecting the
   integrity of the protocol.

   This document is based on the assumption that no additional security
   mechanism such as IPsec is used in the IP layer, as not all MANET
   deployments may be suitable to deploy common IP protection mechanisms
   (e.g., because of limited resources of MANET routers to support the
   IPsec stack).  It assumes that there is no lower-layer protection
   either.  The document analyzes possible attacks on and mis-
   configurations of SMF and outlines the consequences of such attacks/
   mis-configurations to the state maintained by SMF in each router.

   This document aims at analyzing and describing the potential
   vulnerabilities of and attack vectors for SMF.  While completeness in
   such analysis is always a goal, no claims of being complete are made.
   The goal of this document is to be helpful for when deploying SMF in
   a network and needing to understand the risks thereby incurred - as
   well as for providing a reference and documented experience with SMF
   as input for possibly future developments of SMF.

   This document is not intended to propose solutions to the threats
   described.  [RFC7182] provides a framework that can be used with SMF,
   and depending on how it is used - may offer some degree of protection
   against the threats described in this document related to identity

2.  Terminology

   This document uses the terminology and notation defined in [RFC5444],
   [RFC6130], [RFC6621] and [RFC4949].

   Additionally, this document introduces the following terminology:

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   SMF router:  A MANET router, running SMF as specified in [RFC6621].

   Attacker:  A device that is present in the network and intentionally
      seeks to compromise the information bases in SMF routers.  It may
      generate syntactically correct SMF control messages.

   Legitimate SMF router:  An SMF router that is correctly configured
      and not compromised by an attacker.

3.  SMF Threats Overview

   SMF requires an external dynamic neighborhood discovery mechanism in
   order to maintain suitable topological information describing its
   immediate neighborhood, and thereby allowing it to select reduced
   relay sets for forwarding multicast data traffic.  Such an external
   dynamic neighborhood discovery mechanism may be provided by lower-
   layer interface information, by a concurrently operating MANET
   routing protocol that already maintains such information such as
   [RFC7181], or by explicitly using MANET Neighborhood Discovery
   Protocol (NHDP) [RFC6130].  If NHDP is used for neighborhood
   discovery by SMF, SMF implicitly inherits the vulnerabilities of
   NHDP, as discussed in [RFC7186].  As SMF relies on NHDP to assist in
   network layer 2-hop neighborhood discovery (not matter if other
   lower-layer mechanisms are used for 1-hop neighborhood discovery),
   this document assumes that NHDP is used in SMF.  The threats that are
   NHDP-specific are indicated explicitly.

   Based on neighborhood discovery mechanisms, SMF specified two major
   functional components: Duplicate Packet Detection (DPD) and Relay Set
   Selection (RSS).

   DPD is required by SMF in order to be able to detect duplicate
   packets and eliminate their redundant forwarding.  An Attacker has
   two ways in which to harm the DPD mechanisms:

   o  It can "deactivate" DPD, so as to make it such that duplicate
      packets are not correctly detected, and that as a consequence they
      are (redundantly) transmitted, increasing the load on the network,
      draining the batteries of the routers involved, etc.

   o  It can "pre-activate" DPD, so as to make DPD detect a later
      arriving (valid) packet as being a duplicate, which therefore
      won't be forwarded. "

   The attacks on DPD can be achieved by replaying existed packets,
   wrangle sequence numbers, manipulate hash values, etc.  They are
   detailed in Section 4.

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   RSS produces a reduced relay set for forwarding multicast data
   packets across the MANET.  SMF supports the use of several relay set
   algorithms, including E-CDS (Essential Connected Dominating Set)
   [RFC5614], S-MPR (Source-based Multi-point Relay, as known from
   [RFC3626] and [RFC7181]), or MPR-CDS [MPR-CDS].  An Attacker can
   disrupt the RSS algorithm by degrading it to classical flooding, or
   by "masking" certain parts of the routers from the multicasting
   domain.  The attacks to RSS algorithms are detailed in Section 5.

   Other than the attacks on DPD and RSS, a common vulnerability of
   MANETs is "jamming", i.e., a device generates massive amounts of
   interfering radio transmissions, which will prevent legitimate
   traffic (e.g., control traffic as well as data traffic) on part of a
   network.  The attacks on DPD and RSS can be further enhanced by

4.  Threats to Duplicate Packet Detection

   Duplicate Packet Detection (DPD) is required for packet dissemination
   in MANETs because: (1) the packets may be transmitted via the same
   physical interface as the one over which they were received; (2) a
   router may also receive multiple copies of the same packet from
   different neighbors.  DPD is thus used to check if an incoming packet
   has been previously received or not.

   DPD is achieved by maintaining a record of recently processed
   multicast packets, and comparing later received multicast packets
   herewith.  A duplicate packet detected is silently dropped and is not
   inserted into the forwarding path of that router, nor is it delivered
   to an application.  DPD, as proposed by SMF, supports both IPv4 and
   IPv6 and for each suggests two duplicate packet detection mechanisms:
   1) header content identification-based DPD (I-DPD), using packet
   headers, in combination with flow state, to estimate temporal
   uniqueness of a packet, and 2) hash-based DPD (H-DPD), employing
   hashing of selected header fields and payload for the same effect.

   In the following of this section, common threats to packet detection
   mechanisms are first discussed.  Then the threats to I-DPD and H-DPD
   are introduced separately.  The threats described in this section are
   applicable to general SMF implementations, no matter if NHDP is used
   or not.

4.1.  Common Threats to Duplicate Packet Detection Mechanisms

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4.1.1.  Replay Attack

   A replay attack implies that control traffic from one region of the
   network is recorded and replayed in a different region at (almost)
   the same time, or in the same region at a different time.

   One possible replay attack is based on the Time-to-Live (TTL, for
   IPv4) or hop limit (for IPv6) field.  As routers only forward packets
   with TTL > 1, an attacker can forward an otherwise valid packet,
   while drastically reducing the TTL hereof.  This will inhibit
   recipient routers from later forwarding the same multicast packet,
   even if received with a different TTL - essentially an attacker thus
   can instruct its neighbors to block forwarding of valid multicast

   For example, in Figure 1, router A forwards a multicast packet with a
   TTL of 64 to the network.  A, B, and C are legitimate SMF routers,
   and X is the attacker.  In a wireless environment, jitter is commonly
   used to avoid systematic collisions in MAC protocols [RFC5148].  An
   attacker can thus increase the probability that its invalid packets
   arrive first by retransmitting them without jittering.  In this
   example, router X forwards the packet without jittering and reduces
   the TTL to 1.  Router C thus records the duplicate detection value
   (hash value for H-DPD, or the header content of the packets for
   I-DPD) but stops forwarding it to the next hops because of the TTL
   value.  When the same packet with normal TTL value (63 in this case)
   arrives from router B, it will be discarded as duplicate packet.

                                    | X |
                                  --'---' __
           packet with TTL=64    /          \  packet with TTL=1
                                /            \
                            .---.              .---.
                            | A |              | C |
                            '---'              '---'
           packet with TTL=64   \    .---.   /
                                 \-- | B |__/  packet with TTL=63

                                 Figure 1

   As the TTL of a packet is intended to be manipulated by
   intermediaries forwarding it, classic methods such as integrity check
   values (e.g., digital signatures) are typically calculated with
   setting TTL fields to some pre-determined value (e.g., 0) - such is
   for example the case for IPsec Authentication Headers - rendering

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   such an attack more difficult to both detect and counter.

   If the attacker has access to a "wormhole" through the network (a
   directional antenna, a tunnel to a collaborator or a wired
   connection, allowing it to bridge parts of a network otherwise
   distant), it can make sure that the packets with such an artificially
   reduced TTL arrive before their unmodified counterparts.

4.2.  Threats to Identification-based Duplicate Packet Detection

   I-DPD uses a specific DPD identifier in the packet header to identify
   a packet.  By default, such packet identification is not provided by
   the IP packet header (for both IPv4 and IPv6).  Therefore, additional
   identification headers, such as the fragment header, a hop-by-hop
   header option, or IPSec sequencing, must be employed in order to
   support I-DPD.  The uniqueness of a packet can then be identified by
   the source IP address of the packet originator and the sequence
   number (from the fragment header, hop-by-hop header option, or
   IPsec).  By doing so, each intermediate router can keep a record of
   recently received packets and determine whether the incoming packet
   has been received or not.

4.2.1.  Pre-activation Attacks (Pre-Play)

   In a wireless environment, or across any other shared channel, an
   attacker can perceive the identification tuple (source IP address,
   sequence number) of a packet.  It is possible to generate a packet
   with the same (source IP address, sequence number) pair with invalid
   content.  If sequence number progression is predictable, then it is
   trivial to generate and inject invalid packets with "future"
   identification information into the network.  If these invalid
   packets arrive before the legitimate packets that they are spoofing,
   the latter will be treated as a duplicate and discarded.  This can
   prevent multicast packets from reaching parts of the network.

   Figure 2 gives an example of pre-activation attack.  A, B and C are
   legitimate SMF routers, and X is the attacker.  The line between the
   routers presents the packet forwarding.  Router A is the source and
   originates a multicast packet with sequence number n.  When router X
   receives the packet, it generates an invalid packet with the source
   address of A and sequence number n.  If the invalid packet arrives at
   router C before the forwarding of router B, the valid packet will be
   dropped by C as a duplicate packet.  An attacker can manipulate
   jitter to make sure that the invalid packets arrive first.  Router X
   can even generate packets with future sequence numbers (if they are
   predictable), so that the future legitimate packets with the same
   sequence numbers will be dropped as duplicate ones.

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                                | X |
                              --'---' __
       packet with seq=n     /          \  invalid packet with seq=n
                            /            \
                        .---.              .---.
                        | A |              | C |
                        '---'              '---'
       packet with seq=n    \    .---.   /
                             \-- | B |__/  valid packet with seq=n

                                 Figure 2

   As SMF currently does not have any timestamp mechanisms to protect
   data packets, there is no viable way to detect such pre-play attacks
   by way of timestamps.  Especially, if the attack is based on
   manipulation of jitter, the validation of timestamp would not be
   helpful because the timing is still valid (but with much less value).

4.2.2.  De-activation Attacks (Sequence Number wrangling)

   An attacker can also seek to de-activate DPD, by modifying the
   sequence number in packets that it forwards.  Thus, routers will not
   be able to detect an actual duplicate packet as a duplicate - rather,
   they will treat them as new packets, i.e., process and forward them.
   This is similar to DoS attacks, as each packet that is considered
   unique will be multicasted: for a network with n routers, there will
   be n-1 retransmissions.  This can easily cause the "broadcast storm"
   problem discussed in [MOBICOM99].  The consequence of this attack is
   an increased channel load, the origin of which appears to be a router
   other than the attacker.

   Given the topology shown in Figure 2, on receiving a packet with
   seq=n, the attacker X can forward the packet with modified sequence
   number n+i.  This has two consequences: firstly, router C will not be
   able to detect the packet forwarded by X is a duplicate packet;
   secondly, the consequent packet with seq=n+i generated by router A
   probably will be treated as duplicate packet, and dropped by router

4.3.  Threats to Hash-based Duplicate Packet Detection

   When explicit sequence numbers in packet headers is undesired, hash-
   based DPD can be used.  A hash of the non-mutable fields in the
   header of and the data payload can be generated, and recorded at the
   intermediate routers.  A packet can thus be uniquely identified by

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   the source IP address of the packet and its hash-value.

   The hash algorithm used by SMF is being applied only to provide a
   reduced probability of collision and is not being used for
   cryptographic or authentication purposes.  Consequently, a digest
   collision is still possible.  In case the source router or gateway
   identifies that it recently has generated or injected a packet with
   the same hash-value, it inserts a "Hash-Assist Value (HAV)" IPv6
   header option into the packet, such that calculating the hash also
   over this HAV will render the resulting value unique.

4.3.1.  Attack on Hash-Assistant Value

   The HAV header is helpful when a digest collision happens.  However,
   it also introduces a potential vulnerability.  As the HAV option is
   only added when the source or the ingress SMF router detects that the
   coming packet has digest collision with previously generated packets,
   it actually can be regarded as a "flag" of potential digest
   collision.  An attacker can discover the HAV header, and be able to
   conclude that a hash collision is possible if the HAV header is
   removed.  By doing so, the modified packet received by other SMF
   routers will be treated as duplicate packets, and be dropped because
   they have the same hash value with the precedent packet.

   In the example of Figure 3, Router A and B are legitimate SMF
   routers; X is an attacker.  A generates two packets P1 and P2, with
   the same hash value h(P1)=h(P2)=x.  Based on the SMF specification, a
   hash-assistant value (HAV) is added to the latter packet P2, so that
   h(P2+HAV)=x', to avoid digest collision.  When the attacker X detects
   the HAV of P2, it is able to conclude that a collision is possible by
   removing the HAV header.  By doing so, packet P2 will be treated as
   duplicate packet by router B, and be dropped.

              P2            P1                P2         P1
   .---.  h(P2+HAV)=x'    h(P1)=x    .---.  h(P2)=x     h(P1)=x    .---.
   | A |---------------------------> | X | ----------------------> | B |
   `---'                             `---'                         `---'

                                 Figure 3

5.  Threats to Relay Set Selection

   A framework for RSS mechanism, rather than a specific RSS algorithm
   is provided by SMF.  It is normally achieved by distributed

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   algorithms that can dynamically generate a topological Connected
   Dominating Set based on 1-hop and 2-hop neighborhood information.  In
   this section, the common threats to the RSS framework are first
   discussed.  Then the three commonly used algorithms: Essential
   Connection Dominating Set (E-CDS) algorithm, Source-based Multipoint
   Relay (S-MPR) and Multipoint Relay Connected Dominating Set (MPR-CDS)
   are analyzed.  As the relay set selection is based on 1-hop and 2-hop
   neighborhood information, which rely on NHDP, the threats described
   in this section are NHDP-specific.

5.1.  Relay Set Selection Common Threats

   The common threats to RSS algorithms, including Denial of Service
   attack, eavesdropping, message timing attack and broadcast storm have
   been discussed in [RFC7186].

5.2.  Threats to E-CDS Algorithm

   The "Essential Connected Dominating Set" (E-CDS) algorithm [RFC5614]
   forms a single CDS mesh for the SMF operating region.  It requires
   2-hop neighborhood information (the identify of the neighbors, the
   link to the neighbors and neighbors' priority information) collected
   through NHDP or another process.

   An SMF Router select itself as a relay, if:

   o  The SMF Router has a higher priority than all of its symmetric
      neighbors, or

   o  There does not exist a path from the neighbor with largest
      priority to any other neighbor, via neighbors with greater

   An attacker can disrupt the E-CDS algorithm by link spoofing or
   identity spoofing.

5.2.1.  Link Spoofing

   Link spoofing implies that an attacker advertises non-existing links
   to another router (present in the network or not).

   An attacker can declare itself with high route priority, and spoofs
   the links to as many legitimate SMF Routers as possible to declare
   high connectivity.  By doing so, it can prevent legitimate SMF
   Routers from self-selecting as relays.  As the "super" relay in the
   network, the attacker can manipulate the traffic relayed by it.

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5.2.2.  Identity Spoofing

   Identity spoofing implies that an attacker determines and makes use
   of the identity of other legitimate routers, without being authorized
   to do so.  The identity of other routers can be obtained by
   overhearing the control messages or the source/destination address
   from datagrams.  The attacker can then generate control or datagram
   traffic, pretending to be a legitimate router.

   Because E-CDS self-selection is based on the router priority value,
   an attacker can spoof the identity of other legitimate routers, and
   declares a different router priority value.  If it declares a higher
   priority of a spoofed router, it can prevent other routers from
   selecting themselves as relays.  On the other hand, if the attacker
   declares lower priority of a spoofed router, it can enforce other
   routers to selecting themselves as relays, to degrade the multicast
   forwarding to classical flooding.

5.3.  Threats to S-MPR Algorithm

   The source-based multipoint relay (S-MPR) set selection algorithm
   enables individual routers, using 2-hop topology information, to
   select relays from their set of neighboring routers.  MPRs are
   selected so that forwarding to the router's complete 2-hop neighbor
   set is covered.

   An SMF router forwards a multicast packet if and only if:

   o  the packet has not been received received before, and

   o  the neighbor from which the packet was received has selected the
      router as MPR.

   Because MPR calculation is based on the willingness declared by the
   SMF routers, and the connectivity of the routers, it can be disrupted
   by both link spoofing and identity spoofing.  The threats and its
   impacts have been illustrated in section 5.1 of [RFC7186].

5.4.  Threats to MPR-CDS Algorithm

   MPR-CDS is a derivative from S-MPR.  The main difference between
   S-MPR and MPR-CDS is that while S-MPR forms a different broadcast
   tree for each source in the network, MPR-CDS forms a unique broadcast
   tree for all sources in the network.

   As MPR-CDS combines E-CDS and S-MPR and the simple combination of the
   two algorithms does not address the weakness, the vulnerabilities of
   E-CDS and S-MPR that discussed in Section 5.2 and Section 5.3 apply

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   to MPR-CDS also.

6.  Future Work

   Neither [RFC6621] nor this document propose mechanisms to secure the
   SMF protocol.  However, this section aims at discussing possibilities
   to secure the protocol in the future and driving new work by
   suggesting which threats discussed in the previous sections could be

   For the I-DPD mechanism, employing randomized packet sequence numbers
   can avoid some pre-activation attacks based on sequence number
   prediction.  If predicable sequence numbers have to be used, applying
   timestamps can mitigate pre-activation attacks.

   For the H-DPD mechanism, applying cryptographically strong hashes can
   make the digest collisions effectively impossible, and avoid the use
   of hash-assistant value.

   [RFC7182] specifies a framework for representing cryptographic ICVs
   and timestamps in MANETs.  Based on [RFC7182], [RFC7183] specifies
   integrity and replay protection for NHDP using shared keys.  If NHDP
   is used as the neighborhood discovery protocol, [RFC7183] is
   recommended to be implemented to enable integrity protection to NHDP,
   which can help mitigating the threats related to identity spoofing
   through the exchange of HELLO messages.  It provides certain
   protection against identity spoofing by admitting only trusted
   routers to the network using ICVs in HELLO messages.

   However, using ICVs does not address the problem of attackers that
   can generate valid ICVs.  Detecting such attackers could be studied
   in new work.  If [RFC7183] is used, the shared key mechanism will
   make excluding single attackers routers more difficult.  Work could
   be done to facilitate revocation mechanisms in certain MANET use
   cases where routers have sufficient capabilities to support
   asymmetric keys (such as [I-D.ietf-manet-ibs], which is an extension
   of [RFC7182]).

   As [RFC7183] does not protect the integrity of the multicast
   datagram, and no mechanism is specified to do that for SMF yet, the
   duplicate packet detection is still vulnerable to the threats
   introduced in Section 4.

   If pre-activation/de-activation attacks and attack on hash-assistant
   value of the multicast datagrams are to be mitigated, a datagram-
   level integrity protection mechanism is desired, by taking
   consideration of the identity field or hash-assistant value.

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   However, this would not be helpful for the attacks on the TTL (or hop
   limit for IPv6) field, because the mutable fields are generally not
   considered when ICV is calculated.

7.  Security Considerations

   This document does not specify a protocol or a procedure.  The whole
   document, however, reflects on security considerations for SMF for
   packet dissemination in MANETs.

8.  IANA Considerations

   This document contains no actions for IANA.

   [RFC Editor: please remove this section prior to publication.]

9.  Acknowledgments

   The authors would like to thank Christopher Dearlove (BAE Systems
   ATC) who provided detailed review and valuable comments.

10.  References

10.1.  Normative References

   [RFC6130]  Clausen, T., Dean, J., and C. Dearlove, "Mobile Ad Hoc
              Network (MANET) Neighborhood Discovery Protocol (NHDP)",
              RFC 6130, April 2011.

   [RFC6621]  Macker, J., "Simplified Multicast Forwarding", RFC 6621,
              May 2012.

   [RFC7186]  Yi, J., Herberg, U., and T. Clausen, "Security Threats for
              the Neighborhood Discovery Protocol (NHDP)", RFC 7186,
              April 2014.

10.2.  Informative References

              Dearlove, C., "Identity-Based Signatures for MANET Routing
              Protocols", draft-ietf-manet-ibs-04 (work in progress),
              November 2015.


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              Ni, S., Tseng, Y., Chen, Y., and J. Sheu, "The Broadcast
              Storm Problem in a Mobile Ad Hoc Network", Proceedings of
              the 5th annual ACM/IEEE international conference on Mobile
              computing and networking, 1999.

   [MPR-CDS]  Adjih, C., Jacquet, P., and L. Viennot, "Computing
              Connected Dominating Sets with Multipoint Relays", Journal
              of Ad Hoc and Sensor Wireless Networks 2002, January 2002.

   [RFC3626]  Clausen, T. and P. Jacquet, "The Optimized Link State
              Routing Protocol", RFC 3626, October 2003.

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              RFC 4949, August 2007.

   [RFC5148]  Clausen, T., Dearlove, C., and B. Adamson, "Jitter
              Considerations in Mobile Ad Hoc Networks (MANETs)",
              RFC 5148, February 2008.

   [RFC5444]  Clausen, T., Dearlove, C., Dean, J., and C. Adjih,
              "Generalized MANET Packet/Message Format", RFC 5444,
              February 2009.

   [RFC5614]  Ogier, R. and P. Spagnolo, "Mobile Ad Hoc Network (MANET)
              Extension of OSPF Using Connected Dominating Set (CDS)
              Flooding", RFC 5614, August 2009.

   [RFC7181]  Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg,
              "The Optimized Link State Routing Protocol version 2",
              RFC 7181, April 2014.

   [RFC7182]  Herberg, U., Clausen, T., and C. Dearlove, "Integrity
              Check Value and Timestamp TLV Definitions for Mobile Ad
              Hoc Networks (MANETs)", RFC 7182, April 2014.

   [RFC7183]  Herberg, U., Dearlove, C., and T. Clausen, "Integrity
              Protection for the Neighborhood Discovery Protocol (NHDP)
              and Optimized Link State Routing Protocol Version 2
              (OLSRv2)", RFC 7183, April 2014.

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Authors' Addresses

   Jiazi Yi
   LIX, Ecole Polytechnique
   91128 Palaiseau Cedex,

   Phone: +33 1 77 57 80 85

   Thomas Heide Clausen
   LIX, Ecole Polytechnique
   91128 Palaiseau Cedex,

   Phone: +33 6 6058 9349

   Ulrich Herberg


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