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Versions: (draft-yossigi-rpkimaxlen) 00 01 02 03 04 05 06

Network Working Group                                           Y. Gilad
Internet-Draft                            Hebrew University of Jerusalem
Intended status: Best Current Practice                       S. Goldberg
Expires: August 26, 2021                               Boston University
                                                               K. Sriram
                                                                USA NIST
                                                             J. Snijders
                                                                  Fastly
                                                             B. Maddison
                                               Workonline Communications
                                                       February 22, 2021


                    The Use of Maxlength in the RPKI
                    draft-ietf-sidrops-rpkimaxlen-06

Abstract

   This document recommends ways to reduce forged-origin hijack attack
   surface by prudently limiting the set of IP prefixes that are
   included in a Route Origin Authorization (ROA).  One recommendation
   is to avoid using the maxLength attribute in ROAs except in some
   specific cases.  The recommendations complement and extend those in
   RFC 7115.  The document also discusses creation of ROAs for
   facilitating the use of Distributed Denial of Service (DDoS)
   mitigation services.  Considerations related to ROAs and origin
   validation in the context of destination-based Remote Triggered Black
   Hole (RTBH) filtering are also highlighted.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 26, 2021.






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Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements  . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Documentation Prefixes  . . . . . . . . . . . . . . . . .   4
   2.  Suggested Reading . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Forged-Origin Subprefix Hijack  . . . . . . . . . . . . . . .   4
   4.  Measurements of Today's RPKI  . . . . . . . . . . . . . . . .   6
   5.  Recommendations about Minimal ROAs and maxLength  . . . . . .   7
     5.1.  Facilitating Ad-hoc Routing Changes and DDoS Mitigation .   7
   6.  ROAs and Origin Validation for RTBH Filtering Scenario  . . .   9
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  10
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   The RPKI [RFC6480] uses Route Origin Authorizations (ROAs) to create
   a cryptographically verifiable mapping from an IP prefix to a set of
   autonomous systems (ASes) that are authorized to originate that
   prefix.  Each ROA contains a set of IP prefixes, and an AS number of
   an AS authorized to originate all the IP prefixes in the set
   [RFC6482].  The ROA is cryptographically signed by the party that
   holds a certificate for the set of IP prefixes.

   The ROA format also supports a maxLength attribute.  According to
   [RFC6482], "When present, the maxLength specifies the maximum length
   of the IP address prefix that the AS is authorized to advertise."
   Thus, rather than requiring the ROA to list each prefix the AS is
   authorized to originate, the maxLength attribute provides a shorthand
   that authorizes an AS to originate a set of IP prefixes.



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   However, measurements of current RPKI deployments have found that use
   of the maxLength in ROAs tends to lead to security problems.
   Specifically, measurements have shown that 84% of the prefixes
   specified in ROAs that use the maxLength attribute, are vulnerable to
   a forged-origin subprefix hijack [HARMFUL].  The forged-origin prefix
   or subprefix hijack involves inserting the legitimate AS as specified
   in the ROA as the origin AS in the AS_PATH, and can be launched
   against any IP prefix/subprefix that has a ROA.  Consider a prefix/
   subprefix that has a ROA but is unused, i.e., not announced in BGP by
   a legitimate AS.  A forged origin hijack involving such a prefix/
   subprefix can propagate widely throughout the Internet.  On the other
   hand, if the prefix/subprefix were announced by the legitimate AS,
   then the propagation of the forged-origin hijack is somewhat limited
   because of its increased AS_PATH length relative to the legitimate
   announcement.  Of course, forged-origin hijacks are harmful in both
   cases but the extent of harm is greater for unannounced prefixes.

   For this reason, this document recommends that, whenever possible,
   operators SHOULD use "minimal ROAs" that authorize only those IP
   prefixes that are actually originated in BGP, and no other prefixes.
   Further, it recommends ways to reduce forged-origin attack surface by
   prudently limiting the address space that is included in Route Origin
   Authorizations (ROAs).  One recommendation is to avoid using the
   maxLength attribute in ROAs except in some specific cases.  The
   recommendations complement and extend those in [RFC7115].  The
   document also discusses creation of ROAs for facilitating the use of
   Distributed Denial of Service (DDoS) mitigation services.
   Considerations related to ROAs and origin validation in the context
   of destination-based Remote Triggered Black Hole (RTBH) filtering are
   also highlighted.

   One ideal place to implement the ROA related recommendations is in
   the user interfaces for configuring ROAs.  Thus, this document
   further recommends that designers and/or providers of such user
   interfaces SHOULD provide warnings to draw the user's attention to
   the risks of using the maxLength attribute.

   Best current practices described in this document require no changes
   to the RPKI specification and will not increase the number of signed
   ROAs in the RPKI, because ROAs already support lists of IP prefixes
   [RFC6482].

1.1.  Requirements

   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].




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1.2.  Documentation Prefixes

   The documentation prefixes recommended in [RFC5737] are insufficient
   for use as example prefixes in this document.  Therefore, this
   document uses [RFC1918] address space for constructing example
   prefixes.

2.  Suggested Reading

   It is assumed that the reader understands BGP [RFC4271], RPKI
   [RFC6480], Route Origin Authorizations (ROAs) [RFC6482], RPKI-based
   Prefix Validation [RFC6811], and BGPsec [RFC8205].

3.  Forged-Origin Subprefix Hijack

   A detailed description and discussion of forged-origin subprefix
   hijacks are presented here, especially considering the case when the
   subprefix is not announced in BGP.  The forged-origin subprefix
   hijack is relevant to a scenario in which:

      (1) the RPKI [RFC6480] is deployed, and

      (2) routers use RPKI origin validation to drop invalid routes
      [RFC6811], but

      (3) BGPsec [RFC8205] (or any similar method to validate the
      truthfulness of the BGP AS_PATH attribute) is not deployed.

   Note that this set of assumptions accurately describes a substantial,
   and growing, number of large Internet networks at the time writing.

   The forged-origin subprefix hijack [RFC7115] [GCHSS] is described
   here using a running example.

   Consider the IP prefix 192.168.0.0/16 which is allocated to an
   organization that also operates AS 64496.  In BGP, AS 64496
   originates the IP prefix 192.168.0.0/16 as well as its subprefix
   192.168.225.0/24.  Therefore, the RPKI should contain a ROA
   authorizing AS 64496 to originate these two IP prefixes.

   Suppose, however, the organization issues and publishes a ROA
   including a maxLength value of 24:

      ROA:(192.168.0.0/16-24, AS 64496)

   We refer to the above as a "loose ROA" since it authorizes AS 64496
   to originate any subprefix of 192.168.0.0/16 up to and including




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   length /24, rather than only those prefixes that are intended to be
   announced in BGP.

   Because AS 64496 only originates two prefixes in BGP: 192.168.0.0/16
   and 192.168.225.0/24, all other prefixes authorized by the "loose
   ROA" (for instance, 192.168.0.0/24), are vulnerable to the following
   forged-origin subprefix hijack [RFC7115] [GCHSS]:

      The hijacker AS 64511 sends a BGP announcement "192.168.0.0/24: AS
      64511, AS 64496", falsely claiming that AS 64511 is a neighbor of
      AS 64496 and falsely claiming that AS 64496 originates the IP
      prefix 192.168.0.0/24.  In fact, the IP prefix 192.168.0.0/24 is
      not originated by AS 64496.

      The hijacker's BGP announcement is valid according to the RPKI,
      since the ROA (192.168.0.0/16-24, AS 64496) authorizes AS 64496 to
      originate BGP routes for 192.168.0.0/24.

      Because AS 64496 does not actually originate a route for
      192.168.0.0/24, the hijacker's route is the *only* route to the
      192.168.0.0/24.  Longest-prefix-match routing ensures that the
      hijacker's route to the subprefix 192.168.0.0/24 is always
      preferred over the legitimate route to 192.168.0.0/16 originated
      by AS 64496.

   Thus, the hijacker's route propagates through the Internet, the
   traffic destined for IP addresses in 192.168.0.0/24 will be delivered
   to the hijacker.

   The forged-origin *subprefix* hijack would have failed if a "minimal
   ROA" described below was used instead of the "loose ROA".  In this
   example, a "minimal ROA" would be:

      ROA:(192.168.0.0/16, 192.168.225.0/24, AS 64496)

   This ROA is "minimal" because it includes only those IP prefixes that
   AS 64496 originates in BGP, but no other IP prefixes [RFC6907].

   The "minimal ROA" renders AS 64511's BGP announcement invalid,
   because:

      (1) this ROA "covers" the attacker's announcement (since
      192.168.0.0/24 is a subprefix of 192.168.0.0/16), and

      (2) there is no ROA "matching" the attacker's announcement (there
      is no ROA for AS 64511 and IP prefix 192.168.0.0/24) [RFC6811].





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   If routers ignore invalid BGP announcements, the minimal ROA above
   ensures that the subprefix hijack will fail.

   Thus, if a "minimal ROA" had been used, the attacker would be forced
   to launch a forged-origin *prefix* hijack in order to attract
   traffic, as follows:

      The hijacker AS 64511 sends a BGP announcement "192.168.0.0/16: AS
      64511, AS 64496", falsely claiming that AS 64511 is a neighbor of
      AS 64496.

   This forged-origin *prefix* hijack is significantly less damaging
   than the forged-origin *subprefix* hijack:

      AS 64496 legitimately originates 192.168.0.0/16 in BGP, so the
      hijacker AS 64511 is not presenting the *only* route to
      192.168.0.0/16.

      Moreover, the path originated by AS 64511 is one hop longer than
      the path originated by the legitimate origin AS 64496.

   As discussed in [LSG16], this means that the hijacker will attract
   less traffic than he would have in the forged-origin *subprefix*
   hijack, where the hijacker presents the *only* route to the hijacked
   subprefix.

   In summary, a forged-origin subprefix hijack has the same impact as a
   regular subprefix hijack, despite the increased AS_PATH length of the
   illegitimate route.  A forged-origin *subprefix* hijack is also more
   damaging than forged-origin *prefix* hijack.

4.  Measurements of Today's RPKI

   Network measurements have shown that 12% of the IP prefixes
   authorized in ROAs have a maxLength longer than their prefix length.
   Of these, the vast majority (84%) are non-minimal, as they include
   subprefixes that are not announced in BGP by the legitimate AS, and
   are thus vulnerable to forged origin subprefix hijacks.  See [GSG17]
   for details.

   These measurements suggest that operators commonly misconfigure the
   maxLength attribute, and unwittingly open themselves up to forged-
   origin subprefix hijacks.  That is, they are exposing a much larger
   attack surface for forged-origin hijacks than necessary.







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5.  Recommendations about Minimal ROAs and maxLength

   Operators SHOULD use "minimal ROAs" whenever possible.  A minimal ROA
   contains only those IP prefixes that are actually originated by an AS
   in BGP, and no other IP prefixes.  (See Section 3 for an example.)

   In general, except in some special cases, operators SHOULD avoid
   using the maxLength attribute in their ROAs, since its inclusion will
   usually make the ROA non-minimal.

   One such exception may be when all more specific prefixes permitted
   by the maxLength are actually announced by the AS in the ROA.
   Another exception is where: (a) the maxLength is substantially larger
   compared to the specified prefix length in the ROA, and (b) a large
   number of more specific prefixes in that range are announced by the
   AS in the ROA.  This case should occur rarely in practice (if at
   all).  Operator discretion is necessary in this case.

   This practice requires no changes to the RPKI specification and need
   not increase the number of signed ROAs in the RPKI, because ROAs
   already support lists of IP prefixes [RFC6482].  See also [GSG17] for
   further discussion of why this practice will have minimal impact on
   the performance of the RPKI ecosystem.

5.1.  Facilitating Ad-hoc Routing Changes and DDoS Mitigation

   Operational requirements may require that a route for an IP prefix be
   originated on an ad-hoc basis, with little or no prior warning.  An
   example of such a situation arises where an operator wishes to make
   use of DDoS mitigation services that use BGP to redirect traffic via
   a "scrubbing center".

   In order to ensure that such ad-hoc routing changes are effective,
   there should exist a ROA validating the new route.  However a
   difficulty arises due to the fact that newly created objects in the
   RPKI are made visible to relying parties considerabley more slowly
   than routing updates in BGP.

   Ideally, it would not be necessary to pre-create the ROA which
   validates the ad-hoc route, and instead create it "on-the-fly" as
   required.  However, this is practical only if the latency imposed by
   the propagation of RPKI data is guaranteed to be within acceptable
   limits in the circumstances.  For time-critical interventions such as
   responding to a DDoS attack, this is unlikely to be the case.

   Thus, the ROA in question will usually need to be created well in
   advance of the routing intervention, but such a ROA will be non-




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   minimal, since it includes an IP prefix that is sometimes (but not
   always) originated in BGP.

   In this case, the ROA SHOULD include:

      (1) the set of IP prefixes that are always originated in BGP, and

      (2) the set IP prefixes that are sometimes, but not always,
      originated in BGP.

   The ROA SHOULD NOT include any IP prefixes that the operator knows
   will not be originated in BGP.  Whenever possible, the ROA SHOULD
   also avoid the use of the maxLength attribute unless doing so has no
   impact on the set of included prefixes.

   The running example is now extended to illustrate one situation where
   it is not possible to issue a minimal ROA.

   Consider the following scenario prior to deployment of RPKI.  Suppose
   AS 64496 announced 192.168.0.0/16 and has a contract with a
   Distributed Denial of Service (DDoS) mitigation service provider that
   holds AS 64500.  Further, assume that the DDoS mitigation service
   contract applies to all IP addresses covered by 192.168.0.0/22.  When
   a DDoS attack is detected and reported by AS 64496, AS 64500
   immediately originates 192.168.0.0/22, thus attracting all the DDoS
   traffic to itself.  The traffic is scrubbed at AS 64500 and then sent
   back to AS 64496 over a backhaul data link.  Notice that, during a
   DDoS attack, the DDoS mitigation service provider AS 64500 originates
   a /22 prefix that is longer than AS 64496's /16 prefix, and so all
   the traffic (destined to addresses in 192.168.0.0/22) that normally
   goes to AS 64496 goes to AS 64500 instead.  In some deployments, the
   origination of the /22 route is performed by AS 64496 and announced
   only to AS 64500, which then announces transit for that prefix.  This
   variation does not change the properties considered here.

   First, suppose the RPKI only had the minimal ROA for AS 64496, as
   described in Section 3.  But if there is no ROA authorizing AS 64500
   to announce the /22 prefix, then the DDoS mitigation (and traffic
   scrubbing) scheme would not work.  That is, if AS 64500 originates
   the /22 prefix in BGP during DDoS attacks, the announcement would be
   invalid [RFC6811].

   Therefore, the RPKI should have two ROAs: one for AS 64496 and one
   for AS 64500.

      ROA:(192.168.0.0/16, 192.168.225.0/24, AS 64496)

      ROA:(192.168.0.0/22, AS 64500)



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   Neither ROA uses the maxLength attribute.  But the second ROA is not
   "minimal" because it contains a /22 prefix that is not originated by
   anyone in BGP during normal operations.  The /22 prefix is only
   originated by AS 64500 as part of its DDoS mitigation service during
   a DDoS attack.

   Notice, however, that this scheme does not come without risks.
   Namely, all IP addresses in 192.168.0.0/22 are vulnerable to a
   forged-origin subprefix hijack during normal operations, when the /22
   prefix is not originated.  (The hijacker AS 64511 would send the BGP
   announcement "192.168.0.0/22: AS 64511, AS 64500", falsely claiming
   that AS 64511 is a neighbor of AS 64500 and falsely claiming that AS
   64500 originates 192.168.0.0/22.)

   In some situations, the DDoS mitigation service at AS 64500 might
   want to limit the amount of DDoS traffic that it attracts and scrubs.
   Suppose that a DDoS attack only targets IP addresses in
   192.168.0.0/24.  Then, the DDoS mitigation service at AS 64500 only
   wants to attract the traffic designated for the /24 prefix that is
   under attack, but not the entire /22 prefix.  To allow for this, the
   RPKI should have two ROAs: one for AS 64496 and one for AS 64500.

      ROA:(192.168.0.0/16, 192.168.225.0/24, AS 64496)

      ROA:(192.168.0.0/22-24, AS 64500)

   The second ROA uses the maxLength attribute because it is designed to
   explicitly enable AS 64500 to originate *any* /24 subprefix of
   192.168.0.0/22.

   As before, the second ROA is not "minimal" because it contains
   prefixes that are not originated by anyone in BGP during normal
   operations.  As before, all IP addresses in 192.168.0.0/22 are
   vulnerable to a forged-origin subprefix hijack during normal
   operations, when the /22 prefix is not originated.

   The use of maxLength in this second ROA also comes with an additional
   risk.  While it permits the DDoS mitigation service at AS 64500 to
   originate prefix 192.168.0.0/24 during a DDoS attack in that space,
   it also makes the *other* /24 prefixes covered by the /22 prefix
   (i.e., 192.168.1.0/24, 192.168.2.0/24, 192.168.3.0/24) vulnerable to
   a forged-origin subprefix attacks.

6.  ROAs and Origin Validation for RTBH Filtering Scenario

   Considerations related to ROAs and origin validation [RFC6811] for
   the case of destination-based Remote Triggered Black Hole (RTBH)
   filtering are addressed here.  In RTBH filtering, highly specific



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   prefixes (greater than /24 in IPv4 and greater than /48 in IPv6;
   possibly even /32 (IPv4) and /128 (IPv6)) are announced in BGP.
   These announcements are tagged with a BLACKHOLE Community [RFC7999].
   It is obviously not desirable to use large maxlength or include any
   such highly specific prefixes in the ROAs to accommodate destination-
   based RTBH filtering, for the reasons set out above.

   As a result, RPKI based route origin validation [RFC6811] is a poor
   fit for the validation of RTBH routes.  Specification of new
   procedures to address this use case through the use of the RPKI is
   outside the scope of this document.

   Therefore:

   o  Operators SHOULD NOT create non-minimal ROAs (either by creating
      additional ROAs, or through the use of maxLength) for the purpose
      of advertising RTBH routes; and

   o  Operators providing a means for operators of neighboring
      autonomous systems to advertise RTBH routes via BGP MUST NOT make
      the creation of non-minimal ROAs a pre-requisite for its use.

7.  Acknowledgments

   The authors would like to thank the following people for their review
   and contributions to this document: Omar Sagga (Boston University)
   and Aris Lambrianidis (AMS-IX).  Thanks are also due to Matthias
   Waehlisch (Free University of Berlin) for comments and suggestions.

8.  References

8.1.  Normative References

   [RFC1918]  Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
              and E. Lear, "Address Allocation for Private Internets",
              BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996,
              <https://www.rfc-editor.org/info/rfc1918>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.




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   [RFC6480]  Lepinski, M. and S. Kent, "An Infrastructure to Support
              Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
              February 2012, <https://www.rfc-editor.org/info/rfc6480>.

   [RFC6482]  Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
              Origin Authorizations (ROAs)", RFC 6482,
              DOI 10.17487/RFC6482, February 2012,
              <https://www.rfc-editor.org/info/rfc6482>.

   [RFC6811]  Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
              Austein, "BGP Prefix Origin Validation", RFC 6811,
              DOI 10.17487/RFC6811, January 2013,
              <https://www.rfc-editor.org/info/rfc6811>.

8.2.  Informative References

   [GCHSS]    Gilad, Y., Cohen, A., Herzberg, A., Schapira, M., and H.
              Shulman, "Are We There Yet? On RPKI's Deployment and
              Security", in NDSS 2017, February 2017,
              <https://eprint.iacr.org/2016/1010.pdf>.

   [GSG17]    Gilad, Y., Sagga, O., and S. Goldberg, "Maxlength
              Considered Harmful to the RPKI", in ACM CoNEXT 2017,
              December 2017, <https://eprint.iacr.org/2016/1015.pdf>.

   [HARMFUL]  Gilad, Y., Sagga, O., and S. Goldberg, "MaxLength
              Considered Harmful to the RPKI", 2017,
              <https://eprint.iacr.org/2016/1015.pdf>.

   [LSG16]    Lychev, R., Shapira, M., and S. Goldberg, "Rethinking
              Security for Internet Routing", in Communications of the
              ACM, October 2016, <http://cacm.acm.org/
              magazines/2016/10/207763-rethinking-security-for-internet-
              routing/>.

   [NIST-800-189]
              Sriram, K. and D. Montgomery, "Resilient Interdomain
              Traffic Exchange: BGP Security and DDoS Mitigation", NIST
              Special Publication, NIST SP 800-189, December 2019,
              <https://nvlpubs.nist.gov/nistpubs/SpecialPublications/
              NIST.SP.800-189.pdf>.

   [RFC6907]  Manderson, T., Sriram, K., and R. White, "Use Cases and
              Interpretations of Resource Public Key Infrastructure
              (RPKI) Objects for Issuers and Relying Parties", RFC 6907,
              DOI 10.17487/RFC6907, March 2013,
              <https://www.rfc-editor.org/info/rfc6907>.




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   [RFC7115]  Bush, R., "Origin Validation Operation Based on the
              Resource Public Key Infrastructure (RPKI)", BCP 185,
              RFC 7115, DOI 10.17487/RFC7115, January 2014,
              <https://www.rfc-editor.org/info/rfc7115>.

   [RFC7999]  King, T., Dietzel, C., Snijders, J., Doering, G., and G.
              Hankins, "BLACKHOLE Community", RFC 7999,
              DOI 10.17487/RFC7999, October 2016,
              <https://www.rfc-editor.org/info/rfc7999>.

   [RFC8205]  Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol
              Specification", RFC 8205, DOI 10.17487/RFC8205, September
              2017, <https://www.rfc-editor.org/info/rfc8205>.

Authors' Addresses

   Yossi Gilad
   Hebrew University of Jerusalem
   Rothburg Family Buildings, Edmond J. Safra Campus
   Jerusalem  9190416
   Israel

   EMail: yossigi@cs.huji.ac.il


   Sharon Goldberg
   Boston University
   111 Cummington St, MCS135
   Boston, MA  02215
   USA

   EMail: goldbe@cs.bu.edu


   Kotikalapudi Sriram
   USA National Institute of Standards and Technology
   100 Bureau Drive
   Gaithersburg, MD  20899
   USA

   EMail: kotikalapudi.sriram@nist.gov










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   Job Snijders
   Fastly
   Amsterdam
   Netherlands

   EMail: job@fastly.com


   Ben Maddison
   Workonline Communications
   114 West St
   Johannesburg  2196
   South Africa

   EMail: benm@workonline.africa




































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