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KARP                                                         G. Lebovitz
Internet-Draft                                                   Juniper
Intended status: Informational                         February 28, 2010
Expires: September 1, 2010


The Threat Analysis and Requirements for Cryptographic Authentication of
                     Routing Protocols' Transports
                    draft-ietf-karp-threats-reqs-00

Abstract

   In the March of 2006 the IAB held a workshop on the topic of
   "Unwanted Internet Traffic".  The report from that workshop is
   documented in RFC 4948 [RFC4948].  Section 8.2 of RFC 4948 calls for
   "[t]ightening the security of the core routing infrastructure."  Four
   main steps were identified for improving the security of the routing
   infrastructure.  One of those steps was "securing the routing
   protocols' packets on the wire," also called the routing protocol
   transport.  One mechanism for securing routing protocol transports is
   the use of per-packet cryptographic message authentication, providing
   both peer authentication and message integrity.  Many different
   routing protocols exist and they employ a range of different
   transport subsystems.  Therefore there must necessarily be various
   methods defined for applying cryptographic authentication to these
   varying protocols.  Many routing protocols already have some method
   for accomplishing cryptographic message authentication.  However, in
   many cases the existing methods are dated, vulnerable to attack,
   and/or employ cryptographic algorithms that have been deprecated.
   The "Keying and Authentication for Routing Protocols" (KARP) effort
   aims to overhaul and improve these mechanisms.  This document has two
   main parts.  The first describes the threat analysis for attacks
   against routing protocols' transports.  The second enumerates the
   requirements for addressing the described threats.  This document,
   along with the KARP Design Guide and KARP Framework documents, will
   be used by KARP design teams for specific protocol review and
   overhaul.  This document reflects the input of both the IETF's
   Security Area and Routing Area in order to form a jointly agreed upon
   guidance.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-



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   Drafts.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
     1.2.  Requirements Language  . . . . . . . . . . . . . . . . . .  6
     1.3.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     1.4.  Goals  . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     1.5.  Non-Goals  . . . . . . . . . . . . . . . . . . . . . . . . 11
     1.6.  Audience . . . . . . . . . . . . . . . . . . . . . . . . . 11
   2.  Threats  . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     2.1.  Threats In Scope . . . . . . . . . . . . . . . . . . . . . 12
     2.2.  Threats Out of Scope . . . . . . . . . . . . . . . . . . . 14
   3.  Requirements for Phase 1 of a Routing Protocol Transport's
       Security Update  . . . . . . . . . . . . . . . . . . . . . . . 15
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 19
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 19
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19
   7.  Change History (RFC Editor: Delete Before Publishing)  . . . . 19
   8.  Needs Work in Next Draft (RFC Editor: Delete Before
       Publishing)  . . . . . . . . . . . . . . . . . . . . . . . . . 19
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 20
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 20
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22



























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1.  Introduction

   In March 2006 the Internet Architecture Board (IAB) held a workshop
   on the topic of "Unwanted Internet Traffic".  The report from that
   workshop is documented in RFC 4948 [RFC4948].  Section 8.1 of that
   document states that "A simple risk analysis would suggest that an
   ideal attack target of minimal cost but maximal disruption is the
   core routing infrastructure."  Section 8.2 calls for "[t]ightening
   the security of the core routing infrastructure."  Four main steps
   were identified for that tightening:

   o  More secure mechanisms and practices for operating routers.  This
      work is being addressed in the OPSEC Working Group.
   o  Cleaning up the Internet Routing Registry repository [IRR], and
      securing both the database and the access, so that it can be used
      for routing verifications.  This work should be addressed through
      liaisons with those running the IRR's globally.
   o  Specifications for cryptographic validation of routing message
      content.  This work will likely be addressed in the SIDR Working
      Group.
   o  Securing the routing protocols' packets on the wire

   This document addresses the last bullet, securing the packets on the
   wire of the routing protocol exchanges, i.e. the routing protocols'
   transports.  This effort is referred to as Keying and Authentication
   for Routing Protocols, or "KARP".  This document specifically
   addresses the threat analysis for per packet routing protocol
   transport authentication, and the requirements for protocols to
   mitigate those threats.

   This document is one of three that together form the guidance and
   instructions for KARP design teams working to overhaul routing
   protocol transport security.  The other two are the KARP Design Guide
   [I-D.ietf-karp-design-guide] and the KARP Framework
   [I-D.ietf-karp-framework].

1.1.  Terminology

   Within the scope of this document, the following words, when
   beginning with a capital letter, or spelled in all capitals, hold the
   meanings described to the right of each term.  If the same word is
   used uncapitalized, then it is intended to have its common english
   definition.

   [Editor's note: At this point, I'm not sure exactly which of these
   will end up being included in this document.  They came for the
   original "roadmap document".  We can clean out any unused terms a few
   revisions from now.]



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   PSK            Pre-Shared Key. A key used by both peers in a secure
                  configuration.  Usually exchanged out-of-band prior to
                  a first connection.

   Routing Protocol  When used with capital "R" and "P" in this document
                  the term refers the Routing Protocol for which work is
                  being done to provide or enhance its peer
                  authentication mechanisms.

   PRF            Pseudorandom number function, or sometimes called
                  pseudorandom number generator (PRNG).  An algorithm
                  for generating a sequence of numbers that approximates
                  the properties of random numbers.  The sequence is not
                  truly random, in that it is completely determined by a
                  relatively small set of initial values that are passed
                  into the function.  An exmaple is SHA-256.

   KDF            Key derivation function.  A particular specified use
                  of a PRF that takes a PSK, combines it with other
                  inputs to the PRF, and produces a result that is
                  suitable for use as a Traffic Key.

   Identifier     The type and value used by one peer of an
                  authenticated message exchange to signify to the other
                  peer who they are.  The Identifier is used by the
                  receiver as a lookup index into a table containing
                  further information about the peer that is required to
                  continue processing the message, for example a
                  Security Association (SA) or keys.

   Identity Proof A cryptographic proof for an asserted identity, that
                  the peer really is who they assert themselves to be.
                  Proof of identity can be arranged between the peers in
                  a few ways, for example PSK, raw assymetric keys, or a
                  more user-friendly representation of assymetric keys,
                  like a certificate.

   Security Association or SA  The parameters and keys that together
                  form the required information for processing secure
                  sessions between peers.  Examples of items that may
                  exist in an SA include: Identifier, PSK, Traffic Key,
                  cryptographic algorithms, key lifetimes.

   KMP            Key Management Protocol.  A protocol used between
                  peers to exchange SA parameters and Traffic Keys.
                  Examples of KMPs include IKE, TLS, and SSH.





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   KMP Function   Any actual KMP used in the general KARP solution
                  framework

   Peer Key       Keys that are used between peers as the identity
                  proof.  These keys may or may not be connection
                  specific, depending on who they were established, and
                  what form of identity and identity proof is being used
                  in the system.

   Traffic Key    The actual key used on each packet of a message.

   Definitions of items specific to the general KARP framework are
   described in more detail in the KARP Framework
   [I-D.ietf-karp-framework] document.

1.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC2119 [RFC2119].

   When used in lower case, these words convey their typical use in
   common language, and are not to be interpreted as described in
   RFC2119 [RFC2119].

1.3.  Scope

   Four basic tactics may be employed in order to secure any piece of
   data as it is transmitted over the wire: privacy (or encryption),
   authentication, message integrity, and non-repudiation.  The focus
   for this effort, and the scope for this roadmap document, will be
   message authentication and packet integrity only.  This work
   explicitly excludes, at this point in time, the other two tactics:
   privacy and non-repudiation.  Since the objective of most routing
   protocols is to broadly advertise the routing topology, routing
   messages are commonly sent in the clear; confidentiality is not
   normally required for routing protocols.  However, ensuring that
   routing peers truly are the trusted peers expected, and that no roque
   peers or messages can compromise the stability of the routing
   environment is critical, and thus our focus.  The other two
   explicitly excluded tactics, privacy and non-repudiation, may be
   addressed in future work.

   It is possible for routing protocol packets to be transmitted
   employing all four security tactics mentioned above using existing
   standards.  For example, one could run unicast, layer 3 or above
   routing protocol packets through IPsec ESP [RFC4303].  This would



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   provide the added benefit of privacy, and non-repudiation.  However,
   router platforms and systems have been fine tuned over the years for
   the specific processing necessary for routing protocols' non-
   encapsulated formats.  Operators are, therefore, quite reluctant to
   explore new packet encapsulations for these tried and true protocols.

   In addition, at least in the case of OSPF, LDP, and RIP, these
   protocols already have existing mechanisms for cryptographically
   authenticating and integrity checking the packets on the wire.
   Products with these mechanisms have already been produced, code has
   already been written and both have been optimized for the existing
   mechanisms.  Rather than turn away from these mechanisms, we want to
   enhance them, updating them to modern and secure levels.

   Therefore, the scope of this roadmap of work includes:

   o  Making use of existing routing protocol security protocols, where
      they exist, and enhancing or updating them as necessary for modern
      cryptographic best practices,

   o  Developing a framework for using automatic key management in order
      to ease deployment, lower cost of operation, and allow for rapid
      responses to security breaches, and

   o  Specifying the automated key management protocol that may be
      combined with the bits-on-the-wire mechanisms.

   The work also serves as an agreement between the Routing Area and the
   Security Area about the priorities and work plan for incrementally
   delivering the above work.  This point is important.  There will be
   times when the best-security-possible will give way to vastly-
   improved-over-current-security-but-admittedly-not-yet-best-security-
   possible, in order that incremental progress toward a more secure
   Internet may be achieved.  As such, this document will call out
   places where agreement has been reached on such trade offs.

   This document does not contain protocol specifications.  Instead, it
   defines the areas where protocol specification work is needed and
   sets a direction, a set of requirements, and a relative priority for
   addressing that specification work.

   There are a set of threats to routing protocols that are considered
   in-scope for this document/roadmap, and a set considered out-of-
   scope.  These are described in detail in the Threats (Section 2)
   section below.






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1.4.  Goals

   The goals and general guidance for the KARP work follow:

   1. Provide authentication and integrity protection for packets on the
      wire of existing routing protocols

   2. Deliver a path to incrementally improve security of the routing
      infrastructure.  The principle of crawl, walk, run will be in
      place.  Routing protocol authentication mechanisms may not go
      immediately from their current state to a state containing the
      best possible, most modern security practices.  Incremental steps
      will need to be taken for a few very practical reasons.  First,
      there are a considerable number of deployed routing devices in
      operating networks that will not be able to run the most modern
      cryptographic mechanisms without significant and unacceptable
      performance penalties.  The roadmap for any one routing protocol
      MUST allow for incremental improvements on existing operational
      devices.  Second, current routing protocol performance on deployed
      devices has been achieved over the last 20 years through extensive
      tuning of software and hardware elements, and is a constant focus
      for improvement by vendors and operators alike.  The introduction
      of new security mechanisms affects this performance balance.  The
      performance impact of any incremental step of security improvement
      will need to be weighed by the community, and introduced in such a
      way that allows the vendor and operator community a path to
      adoption that upholds reasonable performance metrics.  Therefore,
      certain specification elements may be introduced carrying the
      "SHOULD" guidance, with the intention that the same mechanism will
      carry a "MUST" in the next release of the specification.  This
      gives the vendors and implementors the guidance they need to tune
      their software and hardware appropriately over time.  Last, some
      security mechanisms require the build out of other operational
      support systems, and this will take time.  An example where these
      three reasons are at play in an incremental improvement roadmap is
      seen in the improvement of BGP's [RFC4271] security via the update
      of the TCP Authentication Option (TCP-AO)
      [I-D.ietf-tcpm-tcp-auth-opt] effort.  It would be ideal, and
      reflect best common security practice, to have a fully specified
      key management protocol for negotiating TCP-AO's authentication
      material, using certificates for peer authentication in the
      keying.  However, in the spirit of incremental deployment, we will
      first address issues like cryptographic algorithm agility, replay
      attacks, TCP session resetting in the base TCP-AO protocol before
      we layer key management on top of it.






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   3. The deploy-ability of the improved security solutions on currently
      running routing infrastructure equipment.  This begs the
      consideration of the current state of processing power available
      on routers in the network today.

   4. Operational deploy-ability - A solutions acceptability will also
      be measured by how deployable the solution is by common operator
      teams using common deployment processes and infrastructures.  I.e.
      We will try to make these solutions fit as well as possible into
      current operational practices or router deployment.  This will be
      heavily influenced by operator input, to ensure that what we
      specify can -- and, more importantly, will -- be deployed once
      specified and implemented by vendors.  Deployment of incrementally
      more secure routing infrastructure in the Internet is the final
      measure of success.  Measurably, we would like to see an increase
      in the number of surveyed respondents who report deploying the
      updated authentication mechanisms anywhere across their network,
      as well as a sharp rise in usage for the total percentage of their
      network's routers.

      Interviews with operators show several points about routing
      security.  First, over 70% of operators have deployed transport
      connection protection via TCP-MD5 on their EBGP [ISR2008] .  Over
      55% also deploy MD5 on their IBGP connections, and 50% deploy MD5
      on some other IGP.  The survey states that "a considerable
      increase was observed over previous editions of the survey for use
      of TCP MD5 with external peers (eBGP), internal peers (iBGP) and
      MD5 extensions for IGPs."  Though the data is not captured in the
      report, the authors believe anecdotally that of those who have
      deployed MD5 somewhere in their network, only about 25-30% of the
      routers in their network are deployed with the authentication
      enabled.  None report using IPsec to protect the routing protocol,
      and this was a decline from the few that reported doing so in the
      previous year's report.
      From my personal conversations with operators, of those using MD5,
      almost all report deploying with one single manual key throughout
      the entire network.  These same operators report that the one
      single key has not been changed since it was originally installed,
      sometimes five or more years ago.  When asked why, particularly
      for the case of BGP using TCP MD5, the following reasons are often
      given:


      A.  Changing the keys triggers a TCP reset, and thus bounces the
          links/adjacencies, undermining Service Level Agreements
          (SLAs).




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      B.  For external peers, difficulty of coordination with the other
          organization is an issue.  Once they find the correct contact
          at the other organization (not always so easy), the
          coordination function is serialized and on a per peer/AS
          basis.  The coordination is very cumbersome and tedious to
          execute in practice.
      C.  Keys must be changed at precisely the same time, or at least
          within 60 seconds (as supported by two major vendors) in order
          to limit connectivity outage duration.  This is incredibly
          difficult to do, operationally, especially between different
          organizations.
      D.  Relatively low priority compared to other operatoinal issues.
      E.  Lack of staff to implement the changes device by device.
      F.  There are three use cases for operational peering at play
          here: peers and interconnection with other operators, Internal
          BGP and other routing sessions within a single operator, and
          operator-to-customer-CPE devices.  All three have very
          different properties, and all are reported as cumbersome.  One
          operator reported that the same key is used for all customer
          premise equipment.  The same operator reported that if the
          customer mandated, a unique key could be created, although the
          last time this occurred it created such an operational
          headache that the administrators now usually tell customers
          that the option doesn't even exist, to avoid the difficulties.
          These customer-uniqe keys are never changed, unless the
          customer demands so.
      The main threat at play here is that a terminated employee from
      such an operator who had access to the one (or few) keys used for
      authentication in these environments could easily wage an attack
      -- or offer the keys to others who would wage the attack -- and
      bring down many of the adjacencies, causing destabilization to the
      routing system.

      Whatever mechanisms we specify need to be easier than the current
      methods to deploy, and should provide obvious operational
      efficiency gains along with significantly better security and
      threat protection.  This combination of value may be enough to
      drive much broader adoption.

   5. Address the threats enumerated above in the "Threats" section
      (Section 2) for each routing protocol, along a roadmap.  Not all
      threats may be able to be addressed in the first specification
      update for any one protocol.  Roadmaps will be defined so that
      both the security area and the routing area agree on how the
      threats will be addressed completely over time.






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   6. Create a re-usable architecture, framework, and guidelines for
      various IETF working teams who will address these security
      improvements for various Routing Protocols.  The crux of the KARP
      work is to re-use that framework as much as possible across
      relevant Routing Protocols.  For example, designers should aim to
      re-use the key management protocol that will be defined for BGP's
      TCP-AO key establishment for as many other routing protocols as
      possible.  This is but one example.

   7. Bridge any gaps between IETF's Routing and Security Areas by
      recording agreements on work items, roadmaps, and guidance from
      the Area leads and Internet Architecture Board (IAB, www.iab.org).


1.5.  Non-Goals

   The following two goals are considered out-of-scope for this effort:

   o  Privacy of the packets on the wire, at this point in time.  Once
      this roadmap is realized, we may revisit work on privacy.

   o  Message content security.  This work is being addressed in other
      IETF efforts, like SIDR.

1.6.  Audience

   The audience for this roadmap includes:

   o  Routing Area working group chairs and participants -   These
        people are charged with updates to the Routing Protocol
        specifications.  Any and all cryptographic authentication work
        on these specifications will occur in Routing Area working
        groups, with close partnership with the Security Area.  Co-
        advisors from Security Area may often be named for these
        partnership efforts.

   o  Security Area reviewers of routing area documents -   These people
        are delegated by the Security Area Directors to perform reviews
        on routing protocol specifications as they pass through working
        group last call or IESG review.  They will pay particular
        attention to the use of cryptographic authentication and
        corresponding security mechanisms for the routing protocols.
        They will ensure that incremental security improvements are
        being made, in line with this roadmap.






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   o  Security Area engineers -   These people partner with routing area
        authors/designers on the security mechanisms in routing protocol
        specifications.  Some of these security area engineers will be
        assigned by the Security Area Directors, while others will be
        interested parties in the relevant working groups.

   o  Operators -   The operators are a key audience for this work, as
        the work is considered to have succeeded if the operators deploy
        the technology, presumably due to a perception of significantly
        improved security value coupled with relative similarity to
        deployment complexity and cost.  Conversely, the work will be
        considered a failure if the operators do not care to deploy it,
        either due to lack of value or perceived (or real) over-
        complexity of operations.  And as such, the GROW and OPSEC WGs
        should be kept squarely in the loop as well.




2.  Threats

   In RFC4949[RFC4949], a threat is defined as a potential for violation
   of security, which exists when there is a circumstance, capability,
   action, or event that could breach security and cause harm.  This
   section defines the threats that are in scope for this roadmap, and
   those that are explicitly out of scope.  This document leverages the
   "Generic Threats to Routing Protocols" model, RFC 4593 [RFC4593] ,
   capitalizes terms from that document, and offers a terse definition
   of those terms.  (More thorough description of routing protocol
   threats sources, motivations, consequences and actions can be found
   in RFC 4593 [RFC4593] itself).  The threat listings below expand upon
   these threat definitions.

2.1.  Threats In Scope

   The threats that will be addressed in this roadmap are those from
   OUTSIDERS, attackers that may reside anywhere in the Internet, have
   the ability to send IP traffic to the router, may be able to observe
   the router's replies, and may even control the path for a legitimate
   peer's traffic.  These are not legitimate participants in the routing
   protocol.  Message authentication and integrity protection
   specifically aims to identify messages originating from OUTSIDERS.

   The concept of OUTSIDERS can be further refined to include attackers
   who are terminated employees, and those sitting on-path.





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   o  On-Path - attackers with control of a network resource or a tap
      along the path of packets between two routers.  An on-path
      outsider can attempt a man-in-the-middle attack, in addition to
      several other attack classes.  A man-in-the-middle (MitM) attack
      occurs when an attacker who has access to packets flowing between
      two peers tampers with those packets in such a way that both peers
      think they are talking to each other directly, when in fact they
      are actually talking to the attacker only.  Protocols conforming
      to this roadmap will use cryptographic mechanisms to prevent a
      man-in-the-middle attacker from situating himself undetected.

   o  Terminated Employees - in this context, those who had access
      router configuration that included keys or keying material like
      pre-shared keys used in securing the routing protocol.  Using this
      material, the attacker could send properly MAC'd spoofed packets
      appearing to come from router A to router B, and thus impersonate
      an authorized peer.  The attacker could then send false traffic
      that changes the network behavior from its operator's design.  The
      goal of addressing this source specifically is to call out the
      case where new keys or keying material becomes necessary very
      quickly, with little operational expense, upon the termination of
      such an employee.  This grouping could also refer to any attacker
      who somehow managed to gain access to keying material, and said
      access had been detected by the operators such that the operators
      have an opportunity to move to new keys in order to prevent an
      attack.

   These ATTACK ACTIONS are in scope for this roadmap:

   o  SPOOFING - when an unauthorized device assumes the identity of an
      authorized one.  Spoofing can be used, for example, to inject
      malicious routing information that causes the disruption of
      network services.  Spoofing can also be used to cause a neighbor
      relationship to form that subsequently denies the formation of the
      relationship with the legitimate router.

   o  FALSIFICATION - an action whereby an attacker sends false routing
      information.  To falsify the routing information, an attacker has
      to be either the originator or a forwarder of the routing
      information.  Falsification may occur by an ORIGINATOR, or a
      FORWARDER, and may involve OVERCLAIMING, MISCLAIMING, or
      MISTATEMENT of network resource reachability.  We must be careful
      to remember that in this work we are only targeting falsification
      from outsiders as may occur from tampering with packets in flight.
      Falsification from BYZANTINES (see the Threats Out of Scope
      section (Section 2.2) below) are not addressed by the KARP effort.




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   o  INTERFERENCE - when an attacker inhibits the exchanges by
      legitimate routers.  The types of interference addressed by this
      work include:
      *  ADDING NOISE
      *  REPLAYING OUT-DATED PACKETS
      *  INSERTING MESSAGES
      *  CORRUPTING MESSAGES
      *  BREAKING SYNCHRONIZATION
      *  Changing message content

   o  DoS attacks on transport sub-systems - This includes any other DoS
      attacks specifically based on the above attack types.  This is
      when an attacker sends spoofed packets aimed at halting or
      preventing the underlying protocol over which the routing protocol
      runs, for example halting a BGP session by sending a TCP FIN or
      RST packet.  Since this attack depends on spoofing, operators are
      encouraged to deploy

   o  DoS attacks using the authentication mechanism - This includes an
      attacker sending packets which confuse or overwhelm a security
      mechanism itself.  An example is initiating an overwhelming load
      of spoofed authenticated route messages so that the receiver needs
      to process the MAC check, only to discard the packet, sending CPU
      levels rising.  Another example is when an attacker sends an
      overwhelming load of keying protocol initiations from bogus
      sources.  All other possible DoS attacks are out of scope (see
      next section).

   o  Brute Foce Attacks Against Password/Keys - This includes either
      online or offline attacks where attempts are made repeatedly using
      different keys/passwords until a match is found.  While it is
      impossible to make brute force attacks on keys completely
      unsuccessful, proper design can make such attacks much harder to
      succeed.  For exmaple, the key length should be sufficiently long
      so that covering the entire space of possible keys is improbable
      using computational power expected to be available 10 years out or
      more.  Also, frequently changing the keys may render useless a
      successful guess some time in the future, as those keys may no
      longer be in use.

2.2.  Threats Out of Scope

   Threats from BYZANTINE sources -- faulty, misconfigured, or subverted
   routers, i.e., legitimate participants in the routing protocol -- are
   out of scope for this roadmap.  Any of the attacks described in the
   above section (Section 2.1) that may be levied by a BYZANTINE source
   are therefore also out of scope.



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   In addition, these other attack actions are out of scope for this
   work:

   o  SNIFFING - passive observation of route message contents in flight
   o  FALSIFICATION by BYZANTINE sources - unauthorized message content
      by a legitimate authorized source.
   o  INTERFERENCE due to:
      *  NOT FORWARDING PACKETS - cannot be prevented with cryptographic
         authentication
      *  DELAYING MESSAGES - cannot be prevented with cryptographic
         authentication
      *  DENIAL OF RECEIPT - cannot be prevented with cryptographic
         authentication
      *  UNAUTHORIZED MESSAGE CONTENT - the work of the IETF's SIDR
         working group
         (http://www.ietf.org/html.charters/sidr-charter.html).
      *  Any other type of DoS attack.  For example, a flood of traffic
         that fills the link ahead of the router, so that the router is
         rendered unusable and unreachable by valid packets is NOT an
         attack that this work will address.  Many other such examples
         could be contrived.


3.  Requirements for Phase 1 of a Routing Protocol Transport's Security
    Update

   The following list of requirements SHOULD be addressed by a KARP Work
   Phase 1 security update to any Routing Protocol (according to section
   4.1 of the KARP Design Guide [I-D.ietf-karp-design-guide] document).
   IT IS RECOMMENDED that any Phase 1 security update to a Rouing
   Protocol contain a section of the specification document that
   describes how each of these requirements are met.  It is further
   RECOMMENDED that textual justification be presented for any
   requirements that are NOT addressed.

   1.   Clear definitions of which elements of the transmission (frame,
        packet, segment, etc.) are protected by the authentication
        mechanism
   2.   Strong algorithms, and defined and accepted by the security
        community, MUST be specified.  The option should use algorithms
        considered accepted by the IETF's Security community, which are
        considered appropriately safe.  The use of non-standard or
        unpublished algorithms SHOULD BE avoided.
   3.   Algorithm agility for the cryptograhpic algorithms used in the
        authentication MUST be specified, i.e. more than one algorithm
        MUST be specified and it MUST be clear how new algorithms MAY be
        specified and used within the protocol.  This requirement exists
        in case one algorithm gets broken suddenly.  Research to



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        identify weakness in algorithms is constant.  Breaking a cipher
        isn't a matter of if, but when it will occur.  It's highly
        unlikely that two different algorithms will be broken
        simultaneously.  So, if two are supported, and one gets broken,
        we can use the other until we get a new one in place.  Having
        the ability within the protocol specification to support such an
        event, having algorithm agility, is essential.  Mandating two
        algorithms provides both a redundancy, and a mechanism for
        enacting that redundancy when needed.  Further, the mechanism
        MUST describe the generic interface for new cryptographic
        algorithms to be used, so that implementers can use algorithms
        other than those specified, and so that new algorithms may be
        specifed and supported in the future.
   4.   Secure use of simple PSKs, offering both operational convenience
        as well as building something of a fence around stupidity, MUST
        be specified.
   5.   Inter-connection replay protection.  Packets captured from one
        connection MUST NOT be able to be re-sent and accepted during a
        later connection.
   6.   Intra-connection replay protection.  Packets captured during a
        connection MUST NOT be able to be re-sent and accepted during
        that same connection, to deal with long-lived connections.
        Additionally, replay mechanisms MUST work correctly even in the
        presence of Routing Protocol packet prioritization by the router
        (see requirement 17 below).
   7.   A change of security parameters REQUIRES, and even forces, a
        change of session traffic keys
   8.   Intra-connection re-keying which occurs without a break or
        interruption to the current peering session, and, if possible,
        without data loss, MUST be specified.  Keys need to be changed
        periodically, for operational privacey (e.g. when an
        administrator who had access to the keys leaves an organization)
        and for entropy purposes, and a re-keying mechanism enables the
        deployers to execute the change without productivity loss.
   9.   Efficient re-keying SHOULD be provided.  The specificaion SHOULD
        support rekeying during a connection without the need to expend
        undue computational resources.  In particular, the specification
        SHOULD avoid the need to try/compute multiple keys on a given
        packet.
   10.  Prevent DoS attacks as those described as in-scope in the
        threats section Section 2.1 above.
   11.  Default mechanisms and algorithms specified and defined are
        REQUIRED for all implementations.
   12.  Manual keying MUST be supported.
   13.  Architecture of the specification MUST consider and allow for
        future use of a KMP.





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   14.  The authentication mechanism in the Routing Protocol MUST be
        decoupled from the key management system used.  It MUST be
        obvious how the keying material was obtained, and the process
        for obtaining the keying material MUST exist outside of the
        Routing Protocol.  This will allow for the various key
        generation methods, like manual keys and KMPs, to be used with
        the same Routing Protocol mechanism.
   15.  Convergence times of the Routing Protocols SHOULD NOT be
        materially affected.  Materially here is defined as anything
        greater than a 5% convergence time increase.  Note that
        convergence is different than boot time.  Also note that
        convergence time has a lot to do with the speed of processors
        used on individual routing peers, and this processing power
        increases by Moore's law over time, meaning that the same route
        calculations and table population routines will decrease in
        duration over time.  Therefore, this requirement should be
        considered only in terms of total number of messages that must
        be exchanged, and less for the computational intensity of
        processing any one message.
   16.  The changes or addition of security mechanisms SHOULD NOT cause
        a refresh of route updates or cause additional route updates to
        be generated.
   17.  Router implementations provide prioritized treament to certain
        protocol packets.  For example, OSPF HELLO messages and ACKs are
        prioritized for processing above other OSPF packets.  The
        authentication mechanism SHOULD NOT interfere with the ability
        to observe and enforce such prioritizations.  Any effect on such
        priority mechanisms MUST be explicitly documented and justified.
   18.  The authentication mechanism does not provide message
        confidentiality, but SHOULD NOT preclude the possibility of
        confidentiality support being added in the future.
   19.  The KARP mechanism MUST provide a sufficiently large sequence
        number space so that intra-connection replay protection will
        succeed.  [Editor note: This may be more of a design guide item
        than a requirement?  Also, it may be best to include it with
        3.6?]
   20.  The new security and authentication mechanisms MUST support
        incremental deployment.  It will not be feasible to deploy a new
        Routing Protocol authentication mechanism throughout the network
        instantaneously.  It also may not be possible to deploy such a
        mechanism to all routers in a large autonomous system (AS) at
        one time.  Proposed solutions SHOULD support an incremental
        deployment method that provides some benefit for those who
        participate.  Because of this, there are several requirements
        that any proposed KARP mechanism should consider.
   21.





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        1.   The Routing Protocol security mechanism MUST enable each
             router to configure use of the security mechanism on a per-
             peer basis where the communication is one-on-one.
        2.   The new KARP mechanism MUST provide backward compatibility
             in the message formatting, transmission, and processing of
             routing information carried through a mixed security
             environment.  Message formatting in a fully secured
             environment MAY be handled in a non-backward compatible
             fashion though care must be taken to ensure that routing
             protocol packets can traverse intermediate routers which
             don't support the new format.
        3.   In an environment where both secured and non-secured
             systems are interoperating a mechanism MUST exist for
             secured systems to identify whether an originator intended
             the information to be secured.
        4.   In an environment where secured service is in the process
             of being deployed a mechanism MUST exist to support a
             transition free of service interruption (caused by the
             deployment per se).
   22.  The introduction of mechanisms to improve routing authentication
        and security may increase the processing performed by a router.
        Since most of the currently deployed routers do not have
        hardware to accelerate cryptographic operations, these
        operations could impose a significant processing burden under
        some circumstances.  Thus proposed solutions should be evaluated
        carefully with regard to the processing burden they may impose,
        since deployment may be impeded if network operators perceive
        that a solution will impose a processing burden which either:
   23.
        *    provokes substantial capital expense, or
        *    threatens to destabilize routers.
   24.  Given the high number of routers that would require the new
        authentication mechanisms in a typical ISP deployment, solutions
        can increase their appeal by minimizing the burden imposed on
        all routers in favor of confining significant work loads to a
        relatively small number of devices.  Optional features or
        increased assurance that provokes more pervasive processing load
        MAY be made available for deployments where the additional
        resources are economically justifiable.
   25.  The new authentication and security mechanisms should not rely
        on systems external to the routing system (the equipment that is
        performing forwarding).  In order to ensure the rapid
        initialization and/or return to service of failed nodes it is
        important to reduce reliance on these external systems to the
        greatest extent possible.  Therefore, proposed solutions SHOULD
        NOT require connections to external systems, beyond those
        directly involved in peering relationships, in order to return
        to full service.  It is however acceptable for the proposed



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        solutions to require post initialization synchronization with
        external systems in order to fully synchronize the security
        information.
   26.


4.  Security Considerations

   This document is mostly about security considerations for the KARP
   efforts, both threats and requirements for solving those threats.
   More detailed security considerations were placed in the Security
   Considerations section of the KARP Design Guide
   [I-D.ietf-karp-design-guide] document.


5.  IANA Considerations

   This document has no actions for IANA.


6.  Acknowledgements

   The majority of the text for version -00 of this document was taken
   from draft-lebovitz-karp-roadmap, authored by Gregory Lebovitz.

   Manav Bhatia provided a detailed review of the existing requirements,
   and provided text for a few more.


7.  Change History (RFC Editor: Delete Before Publishing)

   [NOTE TO RFC EDITOR: this section for use during I-D stage only.
   Please remove before publishing as RFC.]

   kmart-00-00 original rough rough rough draft for review by routing
   and security AD's

   karp-threats-reqs-00-

   o  removed all the portions that will be covered in either
      draft-ietf-karp-design-guide or draft-ietf-karp-framework


8.  Needs Work in Next Draft (RFC Editor: Delete Before Publishing)

   [NOTE TO RFC EDITOR: this section for use during I-D stage only.
   Please remove before publishing as RFC.]




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   List of stuff that still needs work
   o  Clean up section 3 requirements, parsing for overlaps, and
      ensuring that each are written in such a way as to be objectively
      either filled or not filled by a KARP spec.
   o  Manav check sect 3 for inclusion of the various requirements you
      sent to Gregory.  Provide clear text for any omissions.
   o  check Brian Weis text on threats against what is in sect 2 already
      to ensure it's covered.
   o  Review by a few other security area folks.


9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4593]  Barbir, A., Murphy, S., and Y. Yang, "Generic Threats to
              Routing Protocols", RFC 4593, October 2006.

   [RFC4948]  Andersson, L., Davies, E., and L. Zhang, "Report from the
              IAB workshop on Unwanted Traffic March 9-10, 2006",
              RFC 4948, August 2007.

9.2.  Informative References

   [I-D.ao-crypto]
              Lebovitz, G., "Cryptographic Algorithms, Use and
              Implementation Requirements for TCP Authentication
              Option", March 2009, <http://tools.ietf.org/html/
              draft-lebovitz-ietf-tcpm-tcp-ao-crypto-00>.

   [I-D.ietf-karp-design-guide]
              Lebovitz, G. and M. Bhatia, "Keying and Authentication for
              Routing Protocols (KARP)  Design Guidelines",
              draft-ietf-karp-design-guide-00 (work in progress),
              February 2010.

   [I-D.ietf-karp-framework]
              Atwood, W. and G. Lebovitz, "Framework for Cryptographic
              Authentication of Routing Protocol Packets on the Wire",
              draft-ietf-karp-framework-00 (work in progress),
              February 2010.

   [I-D.ietf-pim-sm-linklocal]
              Atwood, W., Islam, S., and M. Siami, "Authentication and
              Confidentiality in PIM-SM Link-local Messages",



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              draft-ietf-pim-sm-linklocal-10 (work in progress),
              December 2009.

   [I-D.ietf-tcpm-tcp-auth-opt]
              Touch, J., Mankin, A., and R. Bonica, "The TCP
              Authentication Option", draft-ietf-tcpm-tcp-auth-opt-10
              (work in progress), January 2010.

   [ISR2008]  McPherson, D. and C. Labovitz, "Worldwide Infrastructure
              Security Report", October 2008,
              <http://www.arbornetworks.com/dmdocuments/ISR2008_US.pdf>.

   [RFC1195]  Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
              dual environments", RFC 1195, December 1990.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.

   [RFC2453]  Malkin, G., "RIP Version 2", STD 56, RFC 2453,
              November 1998.

   [RFC3562]  Leech, M., "Key Management Considerations for the TCP MD5
              Signature Option", RFC 3562, July 2003.

   [RFC3618]  Fenner, B. and D. Meyer, "Multicast Source Discovery
              Protocol (MSDP)", RFC 3618, October 2003.

   [RFC3973]  Adams, A., Nicholas, J., and W. Siadak, "Protocol
              Independent Multicast - Dense Mode (PIM-DM): Protocol
              Specification (Revised)", RFC 3973, January 2005.

   [RFC4086]  Eastlake, D., Schiller, J., and S. Crocker, "Randomness
              Requirements for Security", BCP 106, RFC 4086, June 2005.

   [RFC4107]  Bellovin, S. and R. Housley, "Guidelines for Cryptographic
              Key Management", BCP 107, RFC 4107, June 2005.

   [RFC4271]  Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
              Protocol 4 (BGP-4)", RFC 4271, January 2006.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, December 2005.

   [RFC4306]  Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
              RFC 4306, December 2005.




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   [RFC4601]  Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
              "Protocol Independent Multicast - Sparse Mode (PIM-SM):
              Protocol Specification (Revised)", RFC 4601, August 2006.

   [RFC4615]  Song, J., Poovendran, R., Lee, J., and T. Iwata, "The
              Advanced Encryption Standard-Cipher-based Message
              Authentication Code-Pseudo-Random Function-128 (AES-CMAC-
              PRF-128) Algorithm for the Internet Key Exchange Protocol
              (IKE)", RFC 4615, August 2006.

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

   [RFC5036]  Andersson, L., Minei, I., and B. Thomas, "LDP
              Specification", RFC 5036, October 2007.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.


Authors' Addresses

   Gregory Lebovitz
   Juniper Networks, Inc.
   1194 North Mathilda Ave.
   Sunnyvale, CA  94089-1206
   US

   Phone:
   Email: gregory.ietf@gmail.com




   Phone:
   Email:














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