Operational Considerations for use of DNS in IoT devices
draft-richardson-opsawg-mud-iot-dns-considerations-02

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OPSAWG Working Group                                       M. Richardson
Internet-Draft                                  Sandelman Software Works
Intended status: Best Current Practice                     19 March 2020
Expires: 20 September 2020

        Operational Considerations for use of DNS in IoT devices
         draft-richardson-opsawg-mud-iot-dns-considerations-02

Abstract

   This document details concerns about how Internet of Things devices
   use IP addresses and DNS names.  The issue becomes acute as network
   operators begin deploying RFC8520 Manufacturer Usage Description
   (MUD) definitions to control device access.

   This document explains the problem through a series of examples of
   what can go wrong, and then provides some advice on how a device
   manufacturer can best make deal with these issues.  The
   recommendations have an impact upon device and network protocol
   design.

   {RFC-EDITOR, please remove.  Markdown and issue tracker for this
   document is at https://github.com/mcr/iot-mud-dns-considerations.git
   }

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 20 September 2020.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Strategies to map names . . . . . . . . . . . . . . . . . . .   3
   3.  DNS and IP Anti-Patterns for IoT device Manufacturers . . . .   5
     3.1.  Use of IP address literals in-protocol  . . . . . . . . .   5
     3.2.  Use of non-deterministic DNS names in-protocol  . . . . .   6
     3.3.  Use of a too inclusive DNS name . . . . . . . . . . . . .   7
   4.  DNS privacy and outsourcing vs MUD controllers  . . . . . . .   7
   5.  Recommendations to IoT device manufacturer on MUD and DNS
           usage . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Consistently use DNS  . . . . . . . . . . . . . . . . . .   8
     5.2.  Use primary DNS names controlled by the manufacturer  . .   8
     5.3.  Use Content-Distribution Network with stable names  . . .   8
     5.4.  Prefer DNS servers learnt from DHCP/Route
           Advertisements  . . . . . . . . . . . . . . . . . . . . .   8
   6.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Appendix A.  Appendices . . . . . . . . . . . . . . . . . . . . .  12
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   [RFC8520] provides a standardized way to describe how a specific
   purpose device makes use of Internet resources.  Access Control Lists
   (ACLs) can be defined in an RFC8520 Manufacturer Usage Description
   (MUD) file that permit a device to access Internet resources by DNS
   name.

   Use of a DNS name rather than IP address in the ACL has many
   advantages: not only does the layer of indirection permit the mapping
   of name to IP address to be changed over time, it also generalizes
   automatically to IPv4 and IPv6 addresses, as well as permitting
   loading balancing of traffic by many different common ways, including
   geography.

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   At the MUD policy enforcement point - the firewall - there is a
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