BGP Operations and Security

Internet-Draft	BGP OPSEC	October 2025
Fiebig & Hilliard	Expires 7 April 2026	[Page]

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. 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

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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 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.¶
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.¶

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 neighbor permission to announce default routes towards them.¶
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.¶
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 NLRI

When processing NLRI, an operator MUST ensure that basic properties of these NLRI are not altered:¶

An operator MUST NOT change or remove immutable transitive BGP attributes, e.g., ORIGIN as per [RFC4271]. If an attribute is unknown to the operator it must be considered immutable. In selected cases, if a specific attribute is known to be malicious, an operator MAY either temporarily remove that specific attribute from NLRI when importing them or filter NLRI carrying the attribute.¶
NLRI carried on BGP 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].¶

7. References

7.1. 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/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-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/>.