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BMPS: Transport Layer Security for BGP Monitoring Protocol
draft-hmntsharma-bmp-over-tls-00

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Author Hemant Sharma
Last updated 2024-06-30
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draft-hmntsharma-bmp-over-tls-00
GROW                                                           H. Sharma
Internet-Draft                                                  Vodafone
Updates: 7854 (if approved)                                  1 July 2024
Intended status: Informational                                          
Expires: 2 January 2025

       BMPS: Transport Layer Security for BGP Monitoring Protocol
                    draft-hmntsharma-bmp-over-tls-00

Abstract

   The BGP Monitoring Protocol (BMP) defines the communication between a
   BMP station and multiple routers.  This document describes BMP over
   TLS, which uses Transport Layer Security (TLS) to ensure secure
   transport between the router and the BMP monitoring station.  It
   updates [RFC7854] regarding BMP session establishment and
   termination.

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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 2 January 2025.

Copyright Notice

   Copyright (c) 2024 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.

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Table of Contents

   1.  Requirements Language . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  BMP over TLS (BMPS) . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Operational Summary . . . . . . . . . . . . . . . . . . .   3
     3.2.  Transport Layer Security  . . . . . . . . . . . . . . . .   4
     3.3.  Operational Recommendations for BMPS  . . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

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.  Introduction

   The BGP Monitoring Protocol (BMP), as defined in [RFC7854],
   facilitates communication between routers and a BMP station.  Keeping
   this communication secure is important because it includes sharing
   sensitive information about BGP peers and monitored prefixes.

   The Section 11 of [RFC7854] , "Security Considerations" acknowledges
   that while routes in public networks are generally not confidential,
   BGP is also utilized in private L3VPN [RFC4364] networks where
   confidentiality is crucial.  It highlights that without mutual
   authentication through secure transport mechanisms, the channel is
   vulnerable to various attacks and recommends using IPSec [RFC4303] in
   tunnel mode with pre-shared keys for enhanced security in such
   scenarios.

   Additionally, a recent draft proposal, draft-hmntsharma-bmp-tcp-ao,
   titled "TCP-AO Protection for BGP Monitoring Protocol (BMP)" suggests
   an alternative approach using the TCP Authentication Option
   [RFC5925].  This method authenticates the endpoints of the TCP
   session, thereby safeguarding its integrity.  TCP-AO is beneficial in
   situations where full IPSec security may not be feasible, although
   unlike IPSec, it does not encrypt the session traffic.

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   Alternatively, Transport Layer Security (TLS), offers endpoint
   authentication, data encryption, and data integrity defined in The
   Transport Layer Security (TLS) Protocol Version 1.2 [RFC5246] and The
   Transport Layer Security (TLS) Protocol Version 1.3 [RFC8446].

   This document describes how to utilize TLS to secure BMP sessions
   between a monitoring station (acting as the server) and a router
   (acting as the client).  Unlike BGP, where either side can act as the
   server, BMP's role distinction simplifies the implementation of TLS
   in a client-server model.  Henceforth, the term BMP over TLS will be
   referred to as BMPS.

3.  BMP over TLS (BMPS)

3.1.  Operational Summary

   The operation of BMPS is virtually the same as the original BMP
   specification defined in [RFC7854], but with an additional layer of
   security using TLS.

   In BMPS, the BMP station functions as the TLS server, while routers
   act as TLS clients.  Following the completion of the TCP three-way
   handshake, as defined in Section 3.4 of [RFC793], each router,
   functioning as a TLS client, initiates a TLS handshake with the BMP
   monitoring station, acting as the TLS server.  Once the TLS
   connection is successfully established, routers can immediately start
   transmitting BMP messages, as there is no separate BMP initiation or
   handshake phase.

   The following steps summarize the operational flow of BMPS:

   1.  Configure a TLS client profile on the router(s).

   2.  Configure a TLS server profile on the BMP monitoring station(s).

   3.  The router initiates and completes a TCP handshake.

   4.  The router initiates and completes a TLS handshake with the BMP
       monitoring station.

   5.  BMP messages are transmitted by the router according to
       [RFC7854].

   A BMPS session ends when the underlying TCP session utilizing TLS, is
   terminated for any reason.

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   It is RECOMMENDED to adhere to the guidelines in [RFC7525] by
   employing Strict TLS, ensuring that only TLS-secured BMP sessions are
   permitted once the BMP station is configured with a TLS server
   profile.  Furthermore, it is advised to maintain the same TCP port
   for incoming BMP session requests on the BMP station after the TLS
   server profile is applied, for simplified operation.

3.2.  Transport Layer Security

   In regular TLS connections, the server has a TLS certificate along
   with a public/private key pair, whereas the client does not.

   For BMP over TLS (BMPS), it is REQUIRED to implement mutual TLS
   (mTLS), wherein both the server (BMP station) and the client (router)
   have certificates, and both sides authenticate each other using their
   respective public/private key pairs.

   The organizations implementing mTLS SHOULD be their own Certification
   Authority (CA), to create their own self-signed "root" certificate.
   The certificates issued to both the BMP station and routers should
   correspond to this root certificate.

   The operational flow of BMP over TLS is similar to standard TLS
   operations:

   1.  The router initiates the connection to the BMP station.

   2.  The station presents its TLS certificate.

   3.  The router verifies the station's certificate.

   4.  The router presents its TLS certificate.

   5.  The station verifies the router's certificate.

   6.  The TLS connection is established.

   7.  The router begins transmitting BMP data to the station over the
       encrypted TLS channel.

   TLS version 1.3, defined in [RFC8446], streamlines the handshake
   process and supports more robust cipher suites compared to TLS
   version 1.2 [RFC5246], enhancing both speed and security.  However,
   widespread support for TLS 1.3 remains limited, with many systems
   still primarily utilizing TLS 1.2.

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3.3.  Operational Recommendations for BMPS

   The BMP over TLS (BMPS) is RECOMMENDED as an alternative mechanism to
   safeguard BMP sessions in scenarios where alternative protections
   like IPSec may not be feasible or deployed.

4.  Security Considerations

   The BMPS implementation increases computational demands due to
   continuous encryption and decryption processes, resulting in high CPU
   utilization and potential vulnerability to denial-of-service attacks.

   The TLS cipher suites that provide only data integrity validation
   without encryption SHOULD NOT be used by default.

   It is RECOMMENDED to adhere to the Recommendations for Secure Use of
   Transport Layer Security (TLS) and Datagram Transport Layer Security
   (DTLS) as defined in [RFC7525].

5.  IANA Considerations

   This document has no IANA actions.

6.  References

6.1.  Normative References

   [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/rfc/rfc2119>.

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818,
              DOI 10.17487/RFC2818, May 2000,
              <https://www.rfc-editor.org/rfc/rfc2818>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <https://www.rfc-editor.org/rfc/rfc5246>.

   [RFC7854]  Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
              Monitoring Protocol (BMP)", RFC 7854,
              DOI 10.17487/RFC7854, June 2016,
              <https://www.rfc-editor.org/rfc/rfc7854>.

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   [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/rfc/rfc8174>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/rfc/rfc8446>.

6.2.  Informative References

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, DOI 10.17487/RFC4303, December 2005,
              <https://www.rfc-editor.org/rfc/rfc4303>.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <https://www.rfc-editor.org/rfc/rfc4364>.

   [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/rfc/rfc5925>.

   [RFC7525]  Sheffer, Y., Holz, R., and P. Saint-Andre,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", RFC 7525, DOI 10.17487/RFC7525, May 2015,
              <https://www.rfc-editor.org/rfc/rfc7525>.

   [RFC793]   Postel, J., "Transmission Control Protocol", RFC 793,
              DOI 10.17487/RFC0793, September 1981,
              <https://www.rfc-editor.org/rfc/rfc793>.

   [RFC8253]  Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
              "PCEPS: Usage of TLS to Provide a Secure Transport for the
              Path Computation Element Communication Protocol (PCEP)",
              RFC 8253, DOI 10.17487/RFC8253, October 2017,
              <https://www.rfc-editor.org/rfc/rfc8253>.

Acknowledgments

   This document is the result of studying HTTP Over TLS [RFC2818] and
   drawing parallels from PCEPS [RFC8253], leading to the specification
   for BMP over TLS (BMPS).

   We are grateful to the contributors of the RFCs referenced in the
   References section.  Their work has been instrumental in shaping and
   inspiring the development of this specification.

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Author's Address

   Hemant Sharma
   Vodafone
   Email: hemant.sharma@vodafone.com

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