Internet DRAFT - draft-sriram-sidrops-bar-sav

draft-sriram-sidrops-bar-sav







Internet Engineering Task Force (IETF)                         K. Sriram
Internet-Draft                                                  USA NIST
Updates: 8704 (if approved)                                  I. Lubashev
Intended status: Best Current Practice                            Akamai
Expires: 20 June 2023                                      D. Montgomery
                                                                USA NIST
                                                        17 December 2022


  Source Address Validation Using BGP UPDATEs, ASPA, and ROA (BAR-SAV)
                    draft-sriram-sidrops-bar-sav-02

Abstract

   Designing an efficient source address validation (SAV) filter
   requires minimizing false positives (i.e., avoiding dropping
   legitimate traffic) while maintaining directionality (see RFC8704).
   This document advances the technology for SAV filter design through a
   method that makes use of BGP UPDATE messages, Autonomous System
   Provider Authorization (ASPA), and Route Origin Authorization (ROA).
   The proposed method's name is abbreviated as BAR-SAV.  BAR-SAV can be
   used by network operators to derive more robust SAV filters and thus
   improve network resilience.

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 20 June 2023.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.






Sriram, et al.            Expires 20 June 2023                  [Page 1]

Internet-Draft                   BAR-SAV                   December 2022


   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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  Same Procedure Applies to Customers and Lateral Peers . . . .   4
   3.  SAV Using ASPA and ROA (Procedure X)  . . . . . . . . . . . .   4
   4.  SAV using BGP UPDATE Messages, ASPA, and ROA (BAR-SAV)  . . .   5
   5.  Operational Recommendations . . . . . . . . . . . . . . . . .   7
     5.1.  Considerations for the CDN and DSR Scenario . . . . . . .   7
   6.  Operations and Management Considerations  . . . . . . . . . .   9
     6.1.  Applicability of ASPA and ROA . . . . . . . . . . . . . .   9
     6.2.  BAR-SAV and Routing Policy  . . . . . . . . . . . . . . .   9
     6.3.  Where to Deploy BAR-SAV . . . . . . . . . . . . . . . . .  10
     6.4.  Automation is the Key . . . . . . . . . . . . . . . . . .  10
     6.5.  Implementation Guidelines . . . . . . . . . . . . . . . .  10
       6.5.1.  Management of Local RPKI Repository Caches  . . . . .  11
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   Spoofed source addresses are often used in Denial of Service (DoS)
   and Distributed DoS (DDoS) attacks.  Source address validation (SAV)
   filtering is used to drop packets with spoofed source addresses (see
   BCP 84 [RFC3704] [RFC8704]).  A detailed review of unicast Reverse
   Path Forwarding (uRPF) techniques for SAV is provided in [RFC8704]).
   Also, [RFC8704] describes enhanced feasible-path uRPF (EFP-uRPF)
   methods that aim to minimize false positives (i.e., avoid dropping
   legitimate traffic) while maintaining directionality (see definitions
   in [RFC3704]).

   New technology for securing the Border Gateway Protocol (BGP)
   [RFC4271] using Resource Public Key Infrastructure (RPKI) [RFC6480]
   is seeing increasing adoption.  Two of the currently existing or



Sriram, et al.            Expires 20 June 2023                  [Page 2]

Internet-Draft                   BAR-SAV                   December 2022


   proposed types of signed objects in the RPKI can be leveraged for a
   more accurate SAV filter design as well.  These are the Route Origin
   Authorization (ROA) and the Autonomous System Provider Authorizations
   (ASPA) objects.  A ROA is a cryptographically signed attestation by
   an IP address-resource holder listing their prefixes that are
   authorized to be originated in BGP by a specific autonomous system
   (AS) [RFC6482].  ROAs are currently used for RPKI-based Route Origin
   Validation (RPKI-ROV) [RFC6811] [RFC9319].  An ASPA is a
   cryptographically signed attestation by an AS listing its transit
   provider AS numbers (ASNs) [I-D.ietf-sidrops-aspa-profile].  The ASPA
   data is designed to be used for a form of AS path validation that can
   detect and mitigate route leaks [I-D.ietf-sidrops-aspa-verification]
   [sriram1].  See [RFC7908] for the definition of route leaks.

   This document advances the technology for SAV filter design using
   methods that make use of ASPA, ROA, and/or BGP UPDATE data.  A method
   is presented in Section 3 that makes use of only ASPA and ROA data to
   design the SAV filter.  This method is for use in the future when the
   adoption of ROA and ASPA is considered to be ubiquitous.  However,
   for use in the period before that, another method for SAV is
   presented in Section 4 that makes complementary use of BGP UPDATE
   messages along with ASPA and ROA data.  Accordingly, the latter
   method's name is abbreviated as BAR-SAV.  It is hoped that just as
   the adoption of ROAs is growing at present [Monitor], the adoption of
   ASPA will also gain momentum in the near future.  The BAR-SAV method
   additionally incorporates a refined version of Algorithm A of the
   EFP-uRPF technique (Section 3.1 of [RFC8704]).  BAR-SAV can be used
   by network operators to derive more robust SAV filters and thus
   improve network resilience.

   The focus of this document is on the design of ingress SAV filters
   for an interface facing a customer or lateral peer AS.  The same
   procedure applies in both cases (Section 2).

   Throughout this document, ROA and ASPA data mean the payload data in
   cryptographically valid ROA and ASPA objects (see Section 4 in
   [RFC6482] and Section 4 in [I-D.ietf-sidrops-aspa-profile]).

   The reader is encouraged to be familiar with [RFC8704], [RFC6482],
   [RFC6811], [I-D.ietf-sidrops-aspa-profile], and
   [I-D.ietf-sidrops-aspa-verification].










Sriram, et al.            Expires 20 June 2023                  [Page 3]

Internet-Draft                   BAR-SAV                   December 2022


1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Same Procedure Applies to Customers and Lateral Peers

   The same procedure applies for the construction of a permissible
   ingress SAV filter for a customer or lateral peer interface, because
   the data packets received from a customer or lateral peer should have
   source addresses belonging only to the prefixes in the customer cone
   (CC) of said customer or lateral peer.  The focus, therefore, is only
   on the CC of the neighbor in each case.  Note that the CC includes
   the AS belonging to the customer or lateral peer.

3.  SAV Using ASPA and ROA (Procedure X)

   The procedure (called Procedure X) described in this section is for
   future scenarios when ASPA and ROA adoption is ubiquitous.  In that
   scenario, robust SAV filters can be generated from the RPKI
   information (ASPA and ROA data) alone.  The procedure is applicable
   for ingress SAV filter design for customer and lateral peer
   interfaces.  An ISP may use Procedure X on a customer (or lateral
   peer) interface if it expects full adoption of ROAs and ASPAs in the
   CC of the neighbor.

   A description of Procedure X (one that makes use of only ASPA and ROA
   data):

   *  Step A: Compute the set of ASNs in the Customer's or Lateral
      Peer's customer cone using ASPA data.

   *  Step B: Compute from ROA data the set of prefixes authorized to be
      announced by the ASNs found in Step A.  Keep only the unique
      prefixes.  This set is the permissible prefix list for SAV for the
      interface in consideration.

   A detailed description of Procedure X is as follows:

   1.  Let the Customer or Lateral Peer ASN be denoted as AS-k.

   2.  Let i = 1.  Initialize: AS-set S(1) = {AS-k}.

   3.  Increment i to i+1.




Sriram, et al.            Expires 20 June 2023                  [Page 4]

Internet-Draft                   BAR-SAV                   December 2022


   4.  Create AS-set S(i) of all ASNs whose ASPA data declares at least
       one ASN in AS-set S(i-1) as a Provider.

   5.  If AS-set S(i) is null, then set i_max = i - 1 and go to Step 6.
       Else, go to Step 3.

   6.  Form the union of the sets, S(i), i = 1, 2, ..., i_max, and name
       this union as AS-set A.

   7.  Select all ROAs in which the authorized origin ASN is equal to
       any ASN in AS-set A.  Form the union of the sets of prefixes
       listed in the selected ROAs.  Name this union set of prefixes as
       P-set.

   8.  Apply P-set as the list of permissible prefixes for SAV.

4.  SAV using BGP UPDATE Messages, ASPA, and ROA (BAR-SAV)

   SAV using BGP UPDATE Messages, ASPA, and ROA (BAR-SAV) is described
   in this section and is meant for the period when there is a partial
   deployment of ROAs and ASPAs.  To compensate for incomplete RPKI
   information, BAR-SAV augments ASPA data with BGP UPDATE AS_PATH data
   for discovering CC ASes, and it augments ROA data with BGP UPDATE
   data for discovering all prefixes associated with ASes in the CC.
   The details of this procedure are described below.

   BAR-SAV additionally incorporates a refined version of Algorithm A of
   EFP-uRPF (Section 3.1 of [RFC8704]).  Algorithm A in [RFC8704] picked
   only the originating ASes from AS_PATHs received on the customer or
   lateral peer interface in consideration and included them for SAV
   filter computation.  The variant of Algorithm A in [RFC8704] used
   here includes all ASes in the AS_PATHs for the SAV filter
   computation.  Unless there is a route leak [RFC7908], each AS is a
   customer of the AS added next in AS_PATHs of BGP UPDATE messages
   received from a customer or lateral peer.  Further customer-provider
   AS relations within the CC are discovered by examining all unique
   ASes in the AS_PATHs in BGP UPDATEs received on all interfaces (from
   transit providers, customers, lateral peers, and IBGP peers).  This
   is described in the step-by-step procedure later in this section.

   Note that if a multi-homed AS is present in an above-mentioned
   AS_PATH and did not originate any prefix in the CC in consideration
   but originated a prefix into an overlapping neighboring CC, then the
   AS and prefix will still be detected and included in the design of
   the SAV filter.  This improves the accuracy of the SAV filter in the
   BAR-SAV method in comparison to Algorithm A in [RFC8704].





Sriram, et al.            Expires 20 June 2023                  [Page 5]

Internet-Draft                   BAR-SAV                   December 2022


   One should not compute a customer cone by separately processing ASPA
   data and AS_PATH data and then merging the two sets of ASes at the
   end.  Doing so is likely to miss ASes from the customer cone.
   Instead, both ASPAs and AS_PATHs should be used to iteratively expand
   the discovered customer cone.  When new ASes are discovered, both
   ASPA and AS_PATH data should be used to discover customers of those
   ASes.  This process is repeated for newly discovered customer ASes
   until there are no new ASes to be found.

   As a measure of security, validation of the AS_PATH data in Adj-RIBs-
   In [RFC4271] SHOULD be performed using the procedures in
   [I-D.ietf-sidrops-aspa-verification] and any Invalid AS_PATHs must be
   excluded from inputs to the BAR-SAV procedure.  This ensures that BGP
   UPDATEs containing route leaks are not considered for BAR-SAV filter
   design.  Please see additional discussion about route leaks in
   Section 8.

   As a further measure of security, validation of BGP routes in Adj-
   RIBs-In MUST be performed by applying RPKI-ROV [RFC6811] and any
   Invalid routes must be excluded from inputs to the BAR-SAV procedure.
   Please see additional discussion about prefix/route filtering in
   Section 8.

   A detailed description of the BAR-SAV procedure is as follows:

   1.   Let the Customer or Lateral Peer ASN be denoted as AS-k.

   2.   Let i = 1.  Initialize: AS-set Z(1) = {AS-k}.

   3.   Increment i to i+1.

   4.   Create AS-set A(i) of all ASNs whose ASPA data declares at least
        one ASN in AS-set Z(i-1) as a Provider.

   5.   Create AS-set B(i) of all customer ASNs each of which is a
        customer of at least one ASN in AS-set Z(i-1) according to
        unique AS_PATHs in Adj-RIBs-In of all interfaces at the BGP
        speaker computing the SAV filter.

   6.   Form the union of AS-sets A(i) and B(i) and call it AS-set C.
        From AS-set C, remove any ASNs that are present in Z(j), for j=1
        to j=(i-1).  Call the resulting set Z(i).

   7.   If AS-set Z(i) is null, then set i_max = i - 1 and go to Step 8.
        Else, go to Step 3.

   8.   Form the union of the AS-sets, Z(i), i = 1, 2, ..., i_max, and
        name this union as AS-set D.



Sriram, et al.            Expires 20 June 2023                  [Page 6]

Internet-Draft                   BAR-SAV                   December 2022


   9.   Select all ROAs in which the authorized origin ASN is in AS-set
        D.  Form the union of the sets of prefixes listed in the
        selected ROAs.  Name this union set of prefixes as Prefix-set
        P1.

   10.  Using the routes in Adj-RIBs-In of all interfaces, create a list
        of all prefixes originated by any ASN in AS-set D.  Name this
        set of prefixes as Prefix-set P2.

   11.  Form the union of Prefix-sets P1 and P2.  Apply this union set
        as the list of permissible prefixes for SAV.

5.  Operational Recommendations

   Network operators SHOULD implement the BAR-SAV method (Section 4) for
   computing the permissible ingress prefix list for SAV on interfaces
   facing customers and lateral peers.  BAR-SAV offers immediate
   incremental benefits to early adopters.

   The operational recommendations provided in Section 3.2 of [RFC8704]
   are applicable and helpful for BAR-SAV (Section 4).  Since Procedure
   X (Section 3) and the BAR-SAV procedure (Section 4) benefit from the
   registration of ROAs, network operators are RECOMMENDED to register
   ROAs and enable RPKI-ROV in their ASes.  When ASPA registration
   becomes available, network operators are also RECOMMENDED to register
   ASPAs at that time.

   The registration of ROAs and ASPAs helps with the detection and
   inclusion of otherwise hidden prefixes in the permissible list for
   SAV.  As mentioned earlier, prefixes hidden in other SAV techniques
   often arise from the use of multi-homing in conjunction with limited
   propagation of prefixes in a given CC (for example, by attaching
   NO_EXPORT to all prefixes announced from a customer AS to a transit
   provider AS).  In these situations, the registration of ASPAs and
   ROAs helps improve the accuracy of SAV.

5.1.  Considerations for the CDN and DSR Scenario

   Direct Server Return (DSR) is a common asymmetric routing scenario
   that is not supported by existing BCP-84 uRPF [RFC3704] and EFP-uRPF
   [RFC8704] SAV methods.  DSR is commonly used by Content Delivery
   Networks (CDNs) that wish to use anycast service addresses but
   deliver data from edge locations that do not announce anycast
   addresses.

   For example, in Figure 1, the CDN announces an anycast prefix P3
   (from AS3) from a well-connected location with CDN control
   infrastructure.  When a User from prefix P1 (AS1) establishes a



Sriram, et al.            Expires 20 June 2023                  [Page 7]

Internet-Draft                   BAR-SAV                   December 2022


   connection to the anycast address and requests an object, an Anycast
   Server at the CDN may determine that the best location to serve the
   object is an Edge Server in a location close to the User.  The Edge
   Server is reachable only via prefix P2 (AS2).  The Anycast Server can
   forward packets arriving from the User to the Edge Server (via IP-IP
   tunneling or similar means), but the bulk data transmission would
   need to happen directly from the Edge Server to the User with an
   anycast source address (a P3 address).

                    +----------+   P3[AS5 AS3]  +------------+
                    |    AS4   |<---------------|     AS5    |
                    +----------+      (P2P)     +------------+
                        /\   /\                        /\
                        /     \                         \
                P1[AS1]/       \P2[AS2]                  \P3[AS3]
                 (C2P)/         \(C2P)                    \(C2P)
                     /           \                         \
              +----------+    +----------+           +----------+
              |  AS1 (P1)|    | AS2 (P2) |           | AS3 (P3) |
              +-----+----+    +----+-----+           +-----+----+
                    +              +                       +
                  User       Edge Server (DSR)      Anycast Server

             Consider AS4 generating SAV list for interface to AS2:
             CDN's ROAs: {P3 AS3}, {P3, AS2}, {P2, AS2}
             AS2 should not/does not announce P3
             With the SAV methods in this document,
                AS4 correctly includes P2 and P3 in the SAV list

     Figure 1: Illustration of how the solution functions for the CDN/
                               DSR scenario.

   Existing SAV methods of [RFC3704] and EFP-uRPF [RFC8704] would not
   allow AS4 to include P3 as a legitimate SA prefix on the interface to
   AS2.  However, if the CDN (owner of prefix P3) registers a ROA object
   authorizing AS2 to originate P3, and AS4 uses an SAV procedure
   specified in this document (Section 4), then AS4 will use that ROA
   object to include P3 as a valid source prefix for the AS2 customer
   interface.  The CDN may never want to announce a route to P3 from
   AS2, but the existence of this ROA would result in the construction
   of an SAV filter that would permit AS2 to send data packets with
   source addresses belonging to P3.

   The CDN example above is just one DSR scenario.  There are other
   cloud-based DSR scenarios that include low-latency gaming, mobile
   roaming, corporate networks of global enterprises, and others.





Sriram, et al.            Expires 20 June 2023                  [Page 8]

Internet-Draft                   BAR-SAV                   December 2022


   Recommendation: In a DSR scenario, a network operator MUST register
   ROAs that bind the edge server ASes with the anycast service prefix.
   This is in addition to registering a ROA authorizing the anycast
   server AS to announce the anycast prefix.

6.  Operations and Management Considerations

   This section highlights some important operations and management
   considerations and was motivated in part to address the comments
   received from the SIDROPS working group members.

6.1.  Applicability of ASPA and ROA

   A transit provider is a network that (a) offers its customers
   outbound (customer to Internet) data traffic connectivity and/or (b)
   further propagates in all directions (towards providers, lateral
   peers, and other customers) any BGP Updates that the customer may
   send [I-D.ietf-sidrops-aspa-profile].  In the latter case, it also
   provides transport for inbound data traffic.  In all cases, the
   customer AS SHOULD follow the specification in
   [I-D.ietf-sidrops-aspa-profile] and include the transit provider AS
   in its ASPA.  Registering an ASPA prevents forged-origin hijacks for
   the customer AS and its prefixes, prevents route leaks involving the
   customer AS, and facilitates BAR-SAV.

   If a prefix is used for source addresses for hosts attached at an AS
   but not announced in BGP from that AS (e.g., the DSR scenario in
   Section 5.1), a ROA MUST be registered binding the prefix and the AS.
   This ROA registration assists in preventing hijacking of the prefix
   and helps facilitate BAR-SAV.  The risk of this ROA registration
   enabling a forged-origin prefix hijack for the prefix is minimal
   since the ASPA-based path verification
   [I-D.ietf-sidrops-aspa-verification] prevents forged-origin attacks.
   It may be noted that a similar usage of ROA is made in the context of
   DDoS mitigation (see Section 5.1 in [RFC9319]), where hypothetically
   the prefix may never need to be originated by the AS of the DDoS
   mitigation provider.

6.2.  BAR-SAV and Routing Policy

   BAR-SAV identifies all ASes in a customer's (or lateral peer's)
   customer cone (CC), and then it discovers all prefixes that could
   plausibly be used as source addresses in data traffic originated from
   the ASes in the CC.  If ASPA and ROA have been adopted by all ASes
   and prefix owners, respectively, in the CC of interest, then the list
   of plausible source address prefixes will be complete with no
   improper drops (i.e., traffic with legitimate source addresses is not
   dropped).  Further, deploying BAR-SAV by all ASes within the CC



Sriram, et al.            Expires 20 June 2023                  [Page 9]

Internet-Draft                   BAR-SAV                   December 2022


   ensures no improper admits (i.e., traffic with spoofed source address
   is not admitted).  Note that routing policies of ASes may be such
   that some of the discovered prefixes may never be used as source
   addresses on a given customer interface of interest, but this does
   not impact BAR-SAV's accuracy.

6.3.  Where to Deploy BAR-SAV

   The discussion in Section 3.6.1 of [RFC8704] of the Forwarding
   Information Base (FIB) size estimates and the networks where SAV
   would be most effective are applicable to BAR-SAV as well.  Smaller
   ISPs (and possibly some midsize and regional ISPs) are expected to
   implement the BAR-SAV method, since SAV in general is most effective
   closer to the edges of the Internet.  For such networks, the
   conservatively estimated SAV filter list size is only a small
   fraction of the anticipated FIB memory size (see details in
   Section 3.6.1 of [RFC8704]).

6.4.  Automation is the Key

   SAV done manually, e.g., using ACLs, usually does not get much
   adoption because of operational costs, susceptibility to human
   errors, and tendency of SAV filters to get out of date due to the
   need for any changes by customers or peers to be coordinated with
   multiple parties (providers and peers).  Automated uRPF technique,
   such as BAR-SAV, however, allow for easy, accurate, and cost
   effective deployments.  The BAR-SAV method makes it possible to
   automate the construction of SAV filter lists aiming for no improper
   drops and a minimal probability of improper admit of data traffic.
   As ASPA adoption picks up alongside the ongoing ROA adoption, BAR-
   SAV's accuracy of discovering all possible source addresses
   (prefixes) for the customer cone of interest improves even further in
   complex scenarios.

6.5.  Implementation Guidelines

   When a SAV filter is used to police data traffic, and an incomplete
   SAV filter list could cause legitimate traffic to be dropped, the use
   of robust implementation practices for RPKI data retrieval and cache
   management practices become paramount.  Some of such recommended
   practices are discussed in this section.










Sriram, et al.            Expires 20 June 2023                 [Page 10]

Internet-Draft                   BAR-SAV                   December 2022


6.5.1.  Management of Local RPKI Repository Caches

   RPKI infrastructure does not guarantee continuous availability of
   RPKI repositories.  Local caches of RPKI signed objects, manifest
   files (MFTs), and certificate revocation lists (CRLs) are already
   maintained for managing ROA objects and router certificates
   [RFC8210].  That is being extended to ASPA objects as well
   [I-D.ietf-sidrops-8210bis].  The cache refresh frequency currently
   used for RPKI data should be sufficient for BAR-SAV purposes as well.
   If an RPKI repository publication point is unavailable, or there is
   any other failure in fetching its objects, the latest cached version
   of the objects associated with the repository MUST continue to be
   used, as described in [RFC9286].

   If the local cache of some repository objects required for BAR-SAV
   computation is unavailable (for example, due to a filesystem failure)
   and/or the RPKI data cannot be fetched from the repository
   publication point, the SAV system SHOULD "fail open" and downgrade
   the SAV function on a given interface to "loose uRPF" described in
   [RFC3704] and [RFC8704].  This downgrade is better than suspending
   SAV entirely since at least source addresses in unallocated and bogon
   space are rejected.

7.  IANA Considerations

   This document includes no request to IANA.

8.  Security Considerations

   The security considerations described in [RFC8704], [RFC6811],
   [I-D.ietf-sidrops-aspa-profile], and
   [I-D.ietf-sidrops-aspa-verification] also apply to this document.

   The security and robustness of BAR-SAV are strengthened by supporting
   mechanisms for detecting and dropping BGP routes that are
   misoriginations or leaks.  Section 4 stated the requirement of
   validating BGP route origins using RPKI-ROV [RFC6811].  It further
   helps if route origin validation using trusted IRR route objects and
   prefix filtering are also deployed (see [RFC7454] [NIST-800-189]).
   It is also advised that one or more of the available methods to
   prevent, detect, and mitigate route leaks are deployed (e.g.,
   [RFC9234] [I-D.ietf-grow-route-leak-detection-mitigation]
   [I-D.ietf-sidrops-aspa-verification] [sriram1]).

9.  References

9.1.  Normative References




Sriram, et al.            Expires 20 June 2023                 [Page 11]

Internet-Draft                   BAR-SAV                   December 2022


   [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>.

   [RFC3704]  Baker, F. and P. Savola, "Ingress Filtering for Multihomed
              Networks", BCP 84, RFC 3704, DOI 10.17487/RFC3704, March
              2004, <https://www.rfc-editor.org/info/rfc3704>.

   [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>.

   [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>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8704]  Sriram, K., Montgomery, D., and J. Haas, "Enhanced
              Feasible-Path Unicast Reverse Path Forwarding", BCP 84,
              RFC 8704, DOI 10.17487/RFC8704, February 2020,
              <https://www.rfc-editor.org/info/rfc8704>.

9.2.  Informative References

   [RFC7454]  Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations
              and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454,
              February 2015, <https://www.rfc-editor.org/info/rfc7454>.

   [RFC7908]  Sriram, K., Montgomery, D., McPherson, D., Osterweil, E.,
              and B. Dickson, "Problem Definition and Classification of
              BGP Route Leaks", RFC 7908, DOI 10.17487/RFC7908, June
              2016, <https://www.rfc-editor.org/info/rfc7908>.




Sriram, et al.            Expires 20 June 2023                 [Page 12]

Internet-Draft                   BAR-SAV                   December 2022


   [RFC8210]  Bush, R. and R. Austein, "The Resource Public Key
              Infrastructure (RPKI) to Router Protocol, Version 1",
              RFC 8210, DOI 10.17487/RFC8210, September 2017,
              <https://www.rfc-editor.org/info/rfc8210>.

   [RFC9234]  Azimov, A., Bogomazov, E., Bush, R., Patel, K., and K.
              Sriram, "Route Leak Prevention and Detection Using Roles
              in UPDATE and OPEN Messages", RFC 9234,
              DOI 10.17487/RFC9234, May 2022,
              <https://www.rfc-editor.org/info/rfc9234>.

   [RFC9286]  Austein, R., Huston, G., Kent, S., and M. Lepinski,
              "Manifests for the Resource Public Key Infrastructure
              (RPKI)", RFC 9286, DOI 10.17487/RFC9286, June 2022,
              <https://www.rfc-editor.org/info/rfc9286>.

   [RFC9319]  Gilad, Y., Goldberg, S., Sriram, K., Snijders, J., and B.
              Maddison, "The Use of maxLength in the Resource Public Key
              Infrastructure (RPKI)", BCP 185, RFC 9319,
              DOI 10.17487/RFC9319, October 2022,
              <https://www.rfc-editor.org/info/rfc9319>.

   [I-D.ietf-sidrops-aspa-profile]
              Azimov, A., Uskov, E., Bush, R., Snijders, J., Housley,
              R., and B. Maddison, "A Profile for Autonomous System
              Provider Authorization", Work in Progress, Internet-Draft,
              draft-ietf-sidrops-aspa-profile-11, 24 October 2022,
              <https://www.ietf.org/archive/id/draft-ietf-sidrops-aspa-
              profile-11.txt>.

   [I-D.ietf-sidrops-aspa-verification]
              Azimov, A., Bogomazov, E., Bush, R., Patel, K., Snijders,
              J., and K. Sriram, "BGP AS_PATH Verification Based on
              Resource Public Key Infrastructure (RPKI) Autonomous
              System Provider Authorization (ASPA) Objects", Work in
              Progress, Internet-Draft, draft-ietf-sidrops-aspa-
              verification-11, 24 October 2022,
              <https://www.ietf.org/archive/id/draft-ietf-sidrops-aspa-
              verification-11.txt>.

   [I-D.ietf-grow-route-leak-detection-mitigation]
              Sriram, K. and A. Azimov, "Methods for Detection and
              Mitigation of BGP Route Leaks", Work in Progress,
              Internet-Draft, draft-ietf-grow-route-leak-detection-
              mitigation-08, 24 October 2022,
              <https://www.ietf.org/archive/id/draft-ietf-grow-route-
              leak-detection-mitigation-08.txt>.




Sriram, et al.            Expires 20 June 2023                 [Page 13]

Internet-Draft                   BAR-SAV                   December 2022


   [I-D.ietf-sidrops-8210bis]
              Bush, R. and R. Austein, "The Resource Public Key
              Infrastructure (RPKI) to Router Protocol, Version 2", Work
              in Progress, Internet-Draft, draft-ietf-sidrops-8210bis-
              10, 16 June 2022, <https://www.ietf.org/archive/id/draft-
              ietf-sidrops-8210bis-10.txt>.

   [sriram1]  Sriram, K. and J. Heitz, "On the Accuracy of Algorithms
              for ASPA Based Route Leak Detection", IETF SIDROPS
              Meeting, Proceedings of the IETF 110, March 2021,
              <https://datatracker.ietf.org/meeting/110/materials/
              slides-110-sidrops-sriram-aspa-alg-accuracy-01>.

   [Monitor]  "NIST RPKI Monitor", National Institute of Standards and
              Technology, accessed June 2022,
              <https://rpki-monitor.antd.nist.gov/>.

   [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>.

Acknowledgements

   The authors would like to thank Oliver Borchert, Job Snijders, Ben
   Maddison, and Geoff Huston for comments and discussion.

Authors' Addresses

   Kotikalapudi Sriram
   USA National Institute of Standards and Technology
   100 Bureau Drive
   Gaithersburg, MD 20899
   United States of America
   Email: ksriram@nist.gov


   Igor Lubashev
   Akamai Technologies
   145 Broadway
   Cambridge , MA 02142
   United States of America
   Email: ilubashe@akamai.com






Sriram, et al.            Expires 20 June 2023                 [Page 14]

Internet-Draft                   BAR-SAV                   December 2022


   Doug Montgomery
   USA National Institute of Standards and Technology
   100 Bureau Drive
   Gaithersburg, MD 20899
   United States of America
   Email: dougm@nist.gov













































Sriram, et al.            Expires 20 June 2023                 [Page 15]