BGP Operations and Security
draft-ietf-grow-bgpopsecupd-12

Global Routing Operations                                      T. Fiebig
Internet-Draft                                                   MPI-INF
Obsoletes: 7454 (if approved)                                N. Hilliard
Intended status: Best Current Practice                              INEX
Expires: 16 May 2026                                    12 November 2025

                      BGP Operations and Security
                     draft-ietf-grow-bgpopsecupd-12

Abstract

   The Border Gateway Protocol (BGP) is a critical component in the
   Internet to exchange routing information between network domains.
   Due to this central nature, it is important to understand the
   security and reliability requirements that can and should be ensured
   to prevent accidental or intentional routing disturbances.

   Previously, security considerations for BGP have been described in
   RFC7454 / BCP194.  Since the publications of RFC7454, several
   developments and changes in operational practice took place that
   warrant an update of these best current practices.  This document
   obsoletes RFC7454, focusing on the overall goals, and providing a
   less implementation centric set of best practices.

   This document describes security requirements and goals when
   operating BGP for exchanging routing information with other networks,
   and explicitly does not focus on specific technical implementations
   and requirements.

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
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   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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 16 May 2026.

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Copyright Notice

   Copyright (c) 2025 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/
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   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Scope of the Document . . . . . . . . . . . . . . . . . . . .   3
   3.  Protection of the BGP Speaker and Session . . . . . . . . . .   3
     3.1.  BGP Session Protection  . . . . . . . . . . . . . . . . .   3
     3.2.  BGP Speaker Management Interface Protection . . . . . . .   4
   4.  NLRI Filtering  . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Importing NLRI  . . . . . . . . . . . . . . . . . . . . .   4
     4.2.  Originating and Redistributing NLRI . . . . . . . . . . .   5
     4.3.  Altering Attributes in Received BGP Updates . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The Border Gateway Protocol (BGP), specified in [RFC4271], is the
   protocol used in the Internet to exchange routing information between
   network domains.  BGP does not directly include mechanisms that
   control whether the routes exchanged conform to the various
   guidelines defined by the Internet community.  Furthermore, the BGP
   protocol itself, by its design, does not have any direct way to
   protect itself against threats to confidentiality, integrity, and
   availability.

   This document summarizes security properties and requirements when
   operating BGP for securing the infrastructure as well as for security
   considerations regarding the exchanged routing information.  The

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   document explicitly does not focus on specific technical
   implementations and requirements.  Operators are advised to consult
   documentation and contemporary informational documents concerning
   methods to ensure that these properties are sufficiently ensured in
   their network.

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.  Scope of the Document

   The guidelines defined in this document are intended for BGP when
   used to exchange generic Internet routing information within the
   Default-Free Zone (DFZ).  It specifically does not cover other uses
   of BGP, e.g., when using BGP for NLRI exchange in a data-center
   context.  This document does not specify how the outlined
   requirements and properties can be technically realized at a specific
   point in time.  Instead, operators are advised to consult applicable
   documentation and contemporary informational documents describing
   implementation specifics (e.g.,
   [I-D.ietf-grow-routing-ops-sec-inform] and
   [I-D.ietf-grow-routing-ops-terms]).

3.  Protection of the BGP Speaker and Session

   The BGP speaker, i.e., the node running BGP to exchange routing
   information, needs to be protected from external attempts to taint
   integrity or availability of the BGP session and node alike.

3.1.  BGP Session Protection

   To protect a BGP speaker on the network layer, an operator MUST
   ensure the following properties using technical or organizational
   measures:

   *  Prevent off-path attackers from injecting BGP messages into
      existing sessions.

   *  Prevent off-path attackers from interrupting existing sessions.

   *  Prevent off-path attackers from preventing the establishment of
      new sessions.

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   *  Prevent remote systems from overwhelming the BGP speaker by
      sending large volumes of unsolicited packets or BGP messages.

   *  Ensure that unstable sessions do not threaten the availability of
      BGP speakers within the network.

   Example technologies to accomplish this include GTSM/TTL-security
   [RFC5082], BGP-MD5 / TCP-AO [RFC5925], limiting traffic to the
   control plane via Control Plane Policing (CoPP), and setting maximum
   prefix limits for the number of prefixes a neighbor may send.  When
   implementing prefix limits, operators SHOULD be aware of the
   operational implications of exceeding prefix limits, i.e., a loss of
   an established session.  Hence, operators SHOULD appropriately weigh
   this impact within the specific operational circumstances, and ensure
   appropriate prefix limits to not cause outages under normal
   operations.

3.2.  BGP Speaker Management Interface Protection

   In addition to the control plane / exchange of BGP protocol messages,
   the management plane of BGP speakers must be appropriately secured.
   Hence, operators MUST ensure that:

   *  No unauthorized third-parties can obtain access or connect to the
      management interface of a BGP speaker in a way that allows
      tainting confidentiality, integrity, or availability.

   *  External activity towards the management interface does not
      interfere with the integrity or availability of BGP sessions.

4.  NLRI Filtering

   The purpose of BGP is exchanging routing information, i.e., NLRI.
   Importing or exporting incorrect or malicious NLRI is a security risk
   for networks themselves, but may also form a threat for connected
   and/or remote networks.  As such, operators MUST ensure the following
   properties when importing or exporting routing information from their
   neighbors.

4.1.  Importing NLRI

   When importing NLRI from a neighbor, an operator MUST ensure that all
   imported NLRI conform to the following properties by implementing
   technical or organizational measures:

   *  The AS originating NLRI for a prefix MUST be globally authorized
      to originate that prefix.  Operators MAY deviate from this for
      default routes (::/0 and 0.0.0.0/0), if they granted the specific

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      neighbor permission to announce default routes towards them.
      Operators SHOULD be aware that ingesting a default route can have
      opaque negative operational impact, if the announcing upstream is
      not able to cover the more specific forwarding in the appropriate
      service provider context.  These limitations do not materialize
      when receiving a full BGP view.

   *  For received NLRI with an AS_PATH = {AS1, AS2, ..., ASn}, where
      AS1 is the neighbor that sent the UPDATE and ASn is the
      originator, for each k in 1..n−1, AS(k+1) MUST be authorized to
      export the NLRI to ASk according to their bilateral routing policy
      (e.g., provider–customer, peer, or lateral-peer).

   *  The AS_PATH MUST NOT contain AS numbers reserved for private
      [RFC6996] or special-use cases, except for those AS numbers
      explicitly dedicated to a special-use that requires their presence
      in the global routing table [IANAASNSpec].

   *  The number of NLRI received from a neighbor MUST NOT exceed the
      resources of the local router.

4.2.  Originating and Redistributing NLRI

   When originating NLRI or redistributing NLRI received from a
   neighbor, an operator MUST ensure that all NLRI they export conform
   to the following properties by implementing technical or
   organizational measures:

   *  The redistributing AS MUST be authorized to redistribute NLRI for
      the specific prefix when received from the AS directly to its
      right in the AS_PATH.  Additionally, each AS in the AS_PATH not
      originating the prefix MUST be authorized to redistribute the
      prefix when receiving it from the next AS to its right.

   *  The AS originating NLRI for a prefix MUST be globally authorized
      to originate that prefix.  Operators MAY deviate from this for
      default routes (::/0 and 0.0.0.0/0), if they originate the default
      route and the specific neighbor granted them permission to
      announce default routes towards them.  Operators SHOULD be aware
      that originating a default route without being able to cover the
      more specific forwarding in the appropriate service provider
      context can have opaque negative operational impact for a
      downstream, while sharing a full BGP view with a downstream does
      not carry this risk.

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   *  The AS_PATH MUST NOT contain AS numbers reserved for private
      [RFC6996] or special-use cases, except for those AS numbers
      explicitly dedicated to a special-use that requires their presence
      in the global routing table [IANAASNSpec].

4.3.  Altering Attributes in Received BGP Updates

   When processing received BGP updates, an operator SHOULD ensure that
   attributes which are considered immutable are not altered:

   *  An operator SHOULD NOT change or remove immutable transitive BGP
      attributes, e.g., ORIGIN as per [RFC4271].  Furthermore,
      incremental deployment of new features and technologies relies on
      the unaltered redistribution of unknown attributes by
      implementations not yet supporting this feature.  Hence, as
      gratuitously filtering such attributes would harm incremental
      deployment, filtering unknown attributes SHOULD be avoided by
      transit providers.

   *  Please note that occasionally unknown or malformed attributes may
      cause operational problems, e.g., due to implementation bugs.
      Hence, in selected cases, if a specific attribute is known to be
      malicious or disruptive, an operator MAY either temporarily remove
      that specific attribute from received BGP updates when importing
      them or filter the BGP update carrying the attribute.

   *  BGP updates MUST NOT be enriched with transitive attributes
      subject to change independent of the underlying NLRI, e.g.,
      encoding RPKI validation state in transitive attributes
      [I-D.ietf-sidrops-avoid-rpki-state-in-bgp].

5.  IANA Considerations

   This document does not require any IANA actions.

6.  Security Considerations

   This document is entirely about BGP operational security.  It lists
   requirements and properties operators MUST ensure using technical or
   organizational measures when operating BGP routers in the DFZ.

7.  References

7.1.  Normative References

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   [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>.

   [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>.

   [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>.

   [RFC6996]  Mitchell, J., "Autonomous System (AS) Reservation for
              Private Use", BCP 6, RFC 6996, DOI 10.17487/RFC6996, July
              2013, <https://www.rfc-editor.org/info/rfc6996>.

   [IANAASNSpec]
              IANA, "Special-Purpose Autonomous System (AS) Numbers",
              <https://www.iana.org/assignments/iana-as-numbers-special-
              registry/iana-as-numbers-special-registry.xhtml>.

7.2.  Informative References

   [RFC5082]  Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C.
              Pignataro, "The Generalized TTL Security Mechanism
              (GTSM)", RFC 5082, DOI 10.17487/RFC5082, October 2007,
              <https://www.rfc-editor.org/info/rfc5082>.

   [RFC5925]  Touch, J., Mankin, A., and R. Bonica, "The TCP
              Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
              June 2010, <https://www.rfc-editor.org/info/rfc5925>.

   [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>.

   [I-D.ietf-grow-routing-ops-sec-inform]
              Fiebig, T., "Current Options for Securing Global Routing",
              Work in Progress, Internet-Draft, draft-ietf-grow-routing-
              ops-sec-inform, 9 April 2025,
              <https://datatracker.ietf.org/doc/draft-ietf-grow-routing-
              ops-sec-inform/>.

   [I-D.ietf-grow-routing-ops-terms]
              Fiebig, T., "Currently Used Terminology in Global Routing
              Operations", Work in Progress, Internet-Draft, draft-ietf-

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              grow-routing-ops-terms, 9 April 2025,
              <https://datatracker.ietf.org/doc/draft-ietf-grow-routing-
              ops-terms/>.

   [I-D.ietf-sidrops-avoid-rpki-state-in-bgp]
              Snijders, J., Fiebig, T., and M. A. Stucchi, "Guidance to
              Avoid Carrying RPKI Validation States in Transitive BGP
              Path Attributes", Work in Progress, Internet-Draft, draft-
              ietf-sidrops-avoid-rpki-state-in-bgp, 3 October 2024,
              <https://datatracker.ietf.org/doc/draft-ietf-sidrops-
              avoid-rpki-state-in-bgp/>.

Acknowledgements

   This document has been originally based on [RFC7454] and we thank the
   original authors for their work.

   We thank the following people for reviewing this draft and suggesting
   changes:

   *  Gert Doerring

   *  Jeff Haas

   *  Geng Nan

   *  Martin Pels

   *  Job Snijders

   *  Berislav Todorovic

   *  Linda Dunbar

   *  Wolfgang Tremmel

   *  Florian Obser

   *  Ben Maddison

   *  Mohamed Boucadair

Authors' Addresses

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   Tobias Fiebig
   Max-Planck-Institut fuer Informatik
   Campus E14
   66123 Saarbruecken
   Germany
   Phone: +49 681 9325 3527
   Email: tfiebig@mpi-inf.mpg.de

   Nick Hilliard
   Internet Neutral Exchange Association
   4027 Kingswood Road
   Citywest, Dublin
   D24 AX96
   Ireland
   Phone: +353 1 433 205 2
   Email: nick@inex.ie

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