| Internet-Draft | IKv2 for BEET mode ESP | April 2024 |
| Antony & Klassert | Expires 25 October 2024 | [Page] |
This document specifies a new Notify Message Type Payload for the Internet Key Exchange Protocol Version 2 (IKEv2), to negotiate IPsec ESP Bound End-to-End Tunnel (BEET) mode. BEET mode combines the benefits of tunnel mode with reduced overhead, making it suitable for applications requiring minimalistic end-to-end tunnels, mobility support, and multi-address multi-homing capabilities. The introduction of the USE_BEET_MODE Notify Message enables the negotiation and establishment of BEET mode security associations.¶
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The Bound End-to-End Tunnel (BEET) mode, specified in the appendix B of [RFC7402] (Author's note: we propose to write BIZ document for RFC7402 Appendix B, an updated document only for ESP BEET mode) presents an optimized approach for deploying IPsec Encapsulating Security Payload (ESP) by blending the benefits of tunnel and transport modes while minimizing their overhead. The current, [RFC7402] does not specify the negotiation process for establishing BEET mode using the Internet Key Exchange Protocol Version 2 (IKEv2). This document addresses this gap by proposing a new Notify Message Type Payload, USE_BEET_MODE, specifically designed to enable the negotiation and establishment of BEET mode security associations in IKEv2.¶
The introduction of a negotiation mechanism for BEET mode aims to enhance the flexibility and applicability of IPsec, particularly in environments that demand efficient end-to-end security with minimal overhead, such as mobile and multi-homed networks. By providing a standardized method for negotiating BEET mode, this document seeks to facilitate wider adoption and integration into the broader IPsec framework.¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].¶
For over a decade, a minimalist IPsec tunnel mode, BEET, has been in use for end-to-end security in HIP environments without IKE negotiation, [RFC7401] and in many environments using IKE negotiation using a private Notification. (strongSWAN ref)¶
Once IKEv2 negotiation for BEET mode is standardized its potential for enhancing secure communications would increase along with interoperability.¶
Additionally, BEET is valuable for low-power devices, as it reduces power consumption [RFC9333] and complexity. In situations where devices or IPsec connections are dedicated to a single application or transport protocol. In this use case BEET mode simplifies packet processing and conserves energy, especially for lower-powered devices.¶
When negotiating a Child SA using using IKEv2, the initiator may use the new "USE_BEET_MODE" Notify Message to request a Child SA pair with BEET mode support. The method used is similar to how USE_TRANSPORT_MODE is negotiated, as described in [RFC7296]¶
To request a BEET-mode SA on the Child SA pair, the initiator MUST include the USE_BEET_MODE Notify Message when requesting a new Child SA, either during the IKE_AUTH or CREATE_CHILD_SA exchanges. If the request is accepted, the response MUST also include a USE_BEET_MODE Notification. If the responder declines and does not include the USE_BEET_MODE notification in the response, the child SA may be established without BEET mode enabled. If this is unacceptable to the initiator, the initiator MUST delete the child SA.¶
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-----------------------------+-------------------------------+ ! Next Payload !C! RESERVED ! Payload Length ! +---------------+---------------+-------------------------------+ ! Protocol ID ! SPI Size ! Notify Message Type ! +---------------+---------------+-------------------------------+
As the use of the USE_BEET_MODE mode payload is currently only defined for non-transport-mode tunnels, the USE_BEET_MODE notification MUST NOT be combined with the USE_TRANSPORT notification.¶
This document defines a new IKEv2 Notify Message Type payloads for the IANA "IKEv2 Notify Message Types - Status Types" registry.¶
Value Notify Type Messages - Status Types Reference
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[TBD1] USE_BEET_MODE [this document]
In this section we discuss the security properties of the BEET mode, discussing some and point out some of its limitations [RFC3552].¶
There are no known new vulnerabilities that the addition of the BEET mode to IKEv2 would create.¶
Since the BEET security associations have the semantics of a fixed, point-to-point tunnel between two IP addresses, it is possible to place one or both of the tunnel end points into other nodes but those that actually "possess" the inner IP addresses, i.e., to implement a BEET mode proxy. However, since such usage defeats the security benefits of combined ESP processing, as discussed in [I-D.nikander-esp-beet-mode], the implementations SHOULD NOT support such usage.¶
[Note to RFC Editor: Please remove this section and the reference to [RFC6982] before publication.]¶
This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in [RFC7942]. The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist.¶
According to [RFC7942], "this will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. It is up to the individual working groups to use this information as they see fit".¶
Authors are requested to add a note to the RFC Editor at the top of this section, advising the Editor to remove the entire section before publication, as well as the reference to [RFC7942].¶
Linux¶
We extend our sincere gratitude to the authors and contributors who contributed to the standardization of BEET mode. Their insights and dedication have significantly influenced our work, as well as their contributions to the implementation of BEET mode many years ago.¶
This becomes an Appendix.¶