IOTOPS

Summary

The IOTOPS Working Group met at IETF 126 in Vienna. The session covered updates on active working group drafts, potential new adoption items, security baselines for IoT devices, and specialized presentations on DNS privacy for constrained environments and privacy preference declarations. Key outcomes included planning a three-week Working Group Last Call (WGLC) for the YANG licensing draft, coordinating integration between the IoT DNS guidelines draft and DNS over CoAP (DoC) research, and exploring further interest in a security-enabling technologies summary document.

Key Discussion Points

1. Welcome and Administration

Chairs: Alexey Melnikov, Henk Birkholz
Slides: Chair's Slides
The meeting began with agenda bashing to allow Elliot Lear to present early. Daniel Rice announced a post-session demonstration of his privacy preference implementation.

2. Ownership and Licensing Statements in YANG

Presenter: Elliot Lear
Slides: draft-ietf-iotops-ol
Draft Reference: draft-ietf-iotops-ol
Technical Content: The draft addresses the difficulty of sharing YANG-based serializations (such as MUD files) across jurisdictions due to missing copyright/licensing statements. It provides a simple mechanism using either SPDX tags or free text. Recent updates addressed YANG doctor feedback, changing the name from the short ol to owner-license, requiring at least one license, and adopting standard YANG security considerations.
Discussion: Elliot requested progression to Working Group Last Call (WGLC). Jim Mosley agreed to review. The chairs decided to start a three-week WGLC on the mailing list to allow for reviews during and immediately after the IETF week.

3. MUD Extensions and Clarifications

Presenter: Elliot Lear
Slides: MUD extensions and clarifications
Technical Content: This draft represents the start of an update to RFC 8520 (Manufacturer Usage Description). It introduces extensions and clarifications based on deployment experience:
1. IP Addresses: Allowing IP addresses in MUD files despite fragility, as some devices hardcode IPs in firmware.
2. Multicast: Declaring multicast needs that propagate beyond the local link so network operators can provision routing.
3. Directed Broadcasts: Introducing support for directed broadcasts for controllers targeting multiple devices without multicast.
4. Normal Broadcasts: Clarifying that standard broadcasts should be permitted without explicit MUD file rules.
Discussion: Elliot suggested targeting a formal adoption call around the San Francisco meeting, encouraging the working group to read, critique, and propose additional extensions (such as links to SDF models). Alexey Melnikov noted that adoption could proceed sooner if the list is ready. Elliot invited interested participants to join as co-authors or editors.

4. A Summary of Security-Enabling Technologies for IoT Devices

Presenter: Jim Mosley (on behalf of Brendan Moran)
Slides: A Summary of Security-Enabling Technologies for IoT Devices
Technical Content: This expired draft serves as a guide pointing IoT designers to technologies capable of solving specific security requirements derived from ENISA, ETSI, and NIST baselines. The draft mentions creating a threat model, which is currently absent from the text.
Discussion:
- Carsten Bormann suggested limiting the draft's scope strictly to summarizing the three baseline documents to avoid chasing a constantly shifting regulatory landscape.
- Hannes Tschofenig questioned the utility of a manual summary document in the era of AI and new frameworks like the Cyber Resiliency Act (CRA).
- Jim Mosley clarified that the document's true intent is to act as a practical "how-to" implementation guide for manufacturers trying to meet these baselines, rather than just a passive summary.
- Alexey Melnikov characterized the draft as a roadmap pointing to relevant IETF RFCs and external standards.
- The group discussed whether to progress it as-is, split it into modular drafts (e.g., access control, logging), or keep it purely as a reference.

5. IoT DNS Security and Privacy Guidelines

Presenter: Jim Mosley
Slides: IoT DNS Security and Privacy Guidelines
Draft Reference: draft-ietf-iotops-iot-dns-guidelines
Technical Content: This document provides guidance for IoT manufacturers implementing DNS stub resolvers. Version 03 and 04 incorporated early DNS Directorate feedback, separated local network operator guidelines from manufacturer advice, and revised the DNSSEC section.
Discussion:
- Jim outlined areas needing feedback: direct academic paper references for each threat, fingerprinting avoidance, and the addition of a threat-mitigation summary table.
- Regarding DNSSEC, most IoT devices do not perform validation locally; the draft will clarify resource constraints and typical deployment scenarios.
- Addressing hardcoded DNS resolvers (like Google DNS) is planned due to operational fragility.
- Carsten Bormann highlighted the relevance of RFC 9953 (DNS over CoAP). Martin Lenders and Jim Mosley agreed to collaborate to integrate DNS over CoAP recommendations into this document.

6. DNS Privacy Enhancements for the Constrained IoT

Presenter: Martin Lenders
Slides: DNS Privacy Enhancements for the Constrained IoT: DNS over CoAP, SCHC, and Onion CoAP
Technical Content: The presentation analyzed how traditional encrypted DNS protocols (DoH, DoT, DoQ) fail in constrained IoT environments due to TCP and TLS resource overhead. Martin presented an evaluation of RFC 9953 (DNS over CoAP / DoC) and methods to prevent attackers from distinguishing DNS from normal data traffic using machine learning classifiers (Random Forest).
- Information leaks: IP addresses, CoAP URIs, transaction/message IDs, sequence numbers, and OSCORE partial IVs can leak identity.
- Mitigations evaluated: Equalizing block sizes using CoAP blockwise transfer (instead of EDNS(0) padding), using Static Context Header Compression (SCHC) peer-based rules to compress destination headers, and employing Onion CoAP/OSCORE with randomized IDs.
Discussion:
- Christian Amsüss asked which mitigations are practical today. Martin noted that implementing DoC and CoAP blockwise transfer is highly realistic, whereas Onion CoAP is still far from deployment.
- Hannes Tschofenig noted from past IPsec/IPDFS experiments that packet padding alone often fails to hide traffic types from ML classifiers due to packet pacing, but Martin clarified that combining equalized block lengths with header compression yields better results.
- Martin committed to reviewing draft-ietf-iotops-iot-dns-guidelines to assist with WGLC.

7. Privacy Preference Declarations (PPD)

Presenter: Daniel Rice
Slides: Privacy Preference Declarations
Technical Content: This work defines a participant-facing mechanism for households to express unified privacy preferences to IoT devices and services, reducing fragmentation. The work has been split into three documents:
1. Architecture: Focuses on roles, trust boundaries, and lifecycle.
2. Protocol: Specifies operations (discovery, trust establishment, policy retrieval, receipt acknowledgment, and conflict signaling).
3. Taxonomy: Provides a shared semantic core to map diverse vendor vocabularies into a single comparable format.
- Daniel announced a fully functional reference implementation running on OpenWRT with a smart bulb.
Discussion:
- Jim Mosley asked how PPD interacts with regional regulatory frameworks (like GDPR). Daniel noted the protocol is transport-agnostic but designed to allow automatic encoding and deconfliction of regulatory norms.
- Hannes Tschofenig asked about manufacturer requirements. Daniel explained that the baseline requires no action from non-participating vendors. For participating vendors, they register, fetch the policy, and acknowledge it. If a device does not implement PPD, the home router can choose to isolate or segment it based on local policy.

Decisions and Action Items

Decisions:
- Initiate a three-week Working Group Last Call (WGLC) on the mailing list for draft-ietf-iotops-ol.
Action Items:
- Jim Mosley: Post a call to the mailing list seeking co-authors and determining the path forward for the expired draft A Summary of Security-Enabling Technologies for IoT Devices.
- Jim Mosley & Martin Lenders: Collaborate to integrate DNS over CoAP (DoC) considerations (RFC 9953) into draft-ietf-iotops-iot-dns-guidelines.

Next Steps

draft-ietf-iotops-ol: Progress through WGLC; Jim Mosley to submit a review.
draft-ietf-iotops-iot-dns-guidelines: Martin Lenders and other WG members to review before the end of the meeting week to finalize WGLC feedback.
MUD Extensions: WG members to review the newly introduced MUD extensions and clarifications draft on the mailing list to prepare for future adoption.

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