Internet-Draft Owner and Licensing Statements April 2022
Lear & Bormann Expires 26 October 2022 [Page]
Network Working Group
8520 (if approved)
Intended Status:
Standards Track
E. Lear
Cisco Systems
C. Bormann
Universität Bremen TZI

Ownership and licensing statements in YANG


This memo provides for an extension to RFC 8520 that allows MUD file authors to specify ownership and licensing of MUD files themselves. This memo updates RFC 8520. However, it can also be used for purposes outside of MUD, and the grouping is structured as such.

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Table of Contents

1. Introduction

[RFC8520] Manufacturer Usage Descriptions (MUD) can be used to describe devices and their requirements to the network infrastructure. The original version of the specification does not provide for a means to specify ownership and licensing of the MUD file itself. This can hinder those wishing to use, modify, or adapt MUD files for the purpose of offering them, when the manufacturer is not involved.

To avoid any confusion, we define an extension that allows for specifying of owners and licensing terms for MUD files.

Those generating MUD files SHOULD use this extension, and thus this extension updates RFC 8520.

There are two ways to specify a license: a URL pointing to the license itself or an SPDX tag [SPDX]. If an SPDX tag is supplied consumers MUST interpret that tag through its meaning as specified by [SPDX].

This grouping may be used for other YANG models that reside as static objects.

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. The owner-license extension and model

Because the model is primarily motivated by MUD, and based on the way that YANG trees are formed, the model appears as an augmentation for MUD.

module: ietf-ol

  augment /mud:mud:
    +--rw ol
       +--rw owners*               string
       +--rw (license-type)?
          |  +--rw spdx-tag?       string
             +--rw license-info?   inet:uri

3. The YANG schema for ownership and licensing

The following grouping and augmentation are proposed.

<CODE BEGINS>file "ietf-ol@2021-05-21.yang"
module ietf-ol {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-ol";
  prefix ol;

  import ietf-inet-types {
    prefix inet;

  import ietf-mud {
    prefix mud;

    "IETF OPSAWG (Ops Area) Working Group";
     WG List:
     Author: Eliot Lear
     Author: Carsten Bormann <>";
    "This YANG module to indicate ownership and licensing.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject to
     the license terms contained in, the Simplified BSD License set
     forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents

     This version of this YANG module is part of RFC XXXX
     see the RFC itself for full legal notices.

     The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
     'MAY', and 'OPTIONAL' in this document are to be interpreted as
     described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
     they appear in all capitals, as shown here.  ";

  revision 2021-05-21 {
      "Initial proposed standard.";
      "RFC XXXX: Extension for ownership and licensing";

  grouping ol-extension {
      "OL extension grouping";
    container ol {
        "container relating to ownership and licensing.";
      leaf-list owners {
      type string;
          "A list of owners, may be in the form of a copyright
           Example: Copyright (c) Jane Smith.  All rights Reserved.";
      choice license-type {
        description "Either choose a standard license type or point
                     to one of your own.";
        case spdx-lt {
          leaf spdx-tag {
            type string;
            description "SPDX License Identifier, as indicated at
        case url {
          leaf license-info {
            type inet:uri;
            description "A URL pointing to licensing information.";

  augment "/mud:mud" {
      "Add extension for Ownership and licensing.";
    uses ol-extension;


4. Extension for MUD

MUD files using this extension MUST include "ol" in the extensions array, as specified by [RFC8520].

5. Example

In this example, the Frobmaster company is using the 0BSD SPDX tag to indicate a relatively open license. The "ol" extension and container are present. There is a single owner listed.

  "ietf-mud:mud": {
    "mud-version": 1,
    "extensions": [
    "ol": {
      "owners": [
        "Copyright (c) FrobMaster 2021. All Rights Reserved"
      "spdx-tag": "0BSD"
    "mud-url": "",
    "mud-signature": "",
    "last-update": "2021-05-24T11:26:04+00:00",
    "cache-validity": 48,
    "is-supported": true,
    "systeminfo": "This device helps produce frobs",
    "mfg-name": "FrobMaster",
    "documentation": "",
    "model-name": "Frobinator"

6. Security Considerations

The security considerations of Section 16 of [RFC8520] with respect to obtaining validation for information claimed in a MUD file do apply. While the information described in this specification is not intended to directly influence the behavior of protective infrastructure, it may be used by an aggregator as input for deciding the legal basis that enables providing aggregated information; depending on the juridical environment, false information in the MUD file may thus expose the aggregator to additional legal risk.

7. IANA Considerations

7.1. MUD Extension

The IANA is requested to add "ol" to the MUD extensions registry of [IANA.mud] as follows:

Extension Name:


Standard reference:

This document

8. Normative References

IANA, "Manufacturer Usage Description (MUD)", <>.
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage Description Specification", RFC 8520, DOI 10.17487/RFC8520, , <>.
The Linux Foundation, "SPDX Specification 2.1", .

Appendix A. Changes from Earlier Versions

Draft -01:

Draft -00:

Individual Draft -01:

Individual Draft -00:

Authors' Addresses

Eliot Lear
Cisco Systems
Richtistrasse 7
CH-8304 Wallisellen
Carsten Bormann
Universität Bremen TZI
Postfach 330440
D-28359 Bremen