BMPS: Transport Layer Security for BGP Monitoring Protocol
draft-hmntsharma-bmp-over-tls-01
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Hemant Sharma , Steven Clarke | ||
| Last updated | 2024-08-05 | ||
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| Intended RFC status | (None) | ||
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| Stream | Stream state | (No stream defined) | |
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draft-hmntsharma-bmp-over-tls-01
GROW H. Sharma
Internet-Draft S. Clarke
Updates: 7854 (if approved) Vodafone
Intended status: Informational 5 August 2024
Expires: 6 February 2025
BMPS: Transport Layer Security for BGP Monitoring Protocol
draft-hmntsharma-bmp-over-tls-01
Abstract
The BGP Monitoring Protocol (BMP) defines the communication between a
BMP station and multiple routers, referred to as network elements
(NEs). This document describes BMP over TLS, which uses Transport
Layer Security (TLS) to ensure secure transport between the NE 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.
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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 6 February 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
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Please review these documents carefully, as they describe your rights
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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 . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 6
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 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 NEs 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 Network
Element (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 NEs act
as TLS clients. Following the completion of the TCP three-way
handshake, as defined in Section 3.4 of [RFC793], each NE,
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, NEs 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. The NE initiates and completes a TCP handshake.
2. The NE initiates and completes a TLS handshake with the BMP
monitoring station.
3. BMP messages are transmitted by the NE according to [RFC7854].
A BMPS session ends when the underlying TCP or TLS session is
terminated for any reason.
The Section 3.2 of [RFC7854] states, "No BMP message is ever sent
from the monitoring station to the router." To adhere to this
standard, the monitoring station MUST listen on separate ports for
BMP (non-TLS) and BMPS (TLS) sessions. This approach also offers a
simplified "make before break" migration from BMP to BMPS.
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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 (network
element) have certificates, and both sides authenticate each other
using their respective public/private key pairs.
A self-signed "root" TLS certificate is REQUIRED for mTLS, allowing
an organization to act as its own certificate authority. The
certificates issued to both the BMP station and NEs should correspond
to this root certificate.
The operational flow of BMP over TLS is similar to standard TLS
operations:
1. The NE initiates the connection to the BMP station.
2. The station presents its TLS certificate.
3. The NE verifies the station's certificate.
4. The NE presents its TLS certificate.
5. The station verifies the NE's certificate.
6. The TLS connection is established.
7. The NE 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.
The BMPS is REQUIRED to support TLS 1.2 or higher to ensure secure
communication.
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.
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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.
The BMPS implementation SHOULD follow the best practices and
recommendations for using TLS, as per 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>.
[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>.
[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>.
[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>.
[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>.
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[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
[draft-hmntsharma-bmp-tcp-ao]
Sharma, H. and J. Haas, "TCP-AO Protection for BGP
Monitoring Protocol (BMP)", Work in Progress, Internet-
Draft, draft-hmntsharma-bmp-tcp-ao-03, 11 April 2024,
<https://datatracker.ietf.org/doc/html/draft-hmntsharma-
bmp-tcp-ao-03>.
[I-D.hmntsharma-bmp-tcp-ao]
Sharma, H. and J. Haas, "TCP-AO Protection for BGP
Monitoring Protocol (BMP)", Work in Progress, Internet-
Draft, draft-hmntsharma-bmp-tcp-ao-03, 11 April 2024,
<https://datatracker.ietf.org/doc/html/draft-hmntsharma-
bmp-tcp-ao-03>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000,
<https://www.rfc-editor.org/rfc/rfc2818>.
[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>.
[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>.
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Acknowledgments
This document is the result of studying all the referenced RFCs and
drawing some parallels from PCEPS [RFC8253], leading to the
specification for BMP over TLS (BMPS).
We are grateful to the contributors of the RFCs listed in the
References section. Their work has been instrumental in shaping and
inspiring the development of this specification.
Authors' Addresses
Hemant Sharma
Vodafone
Email: hemant.sharma@vodafone.com
Steven Clarke
Vodafone
Email: steven.clarke@vodafone.com
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