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Versions: 00

OPSAWG Working Group                                       M. Richardson
Internet-Draft                                  Sandelman Software Works
Intended status: Best Current Practice                     July 08, 2019
Expires: January 9, 2020


        Operational Considerations for use of DNS in IoT devices
         draft-richardson-opsawg-mud-iot-dns-considerations-00

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.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   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 January 9, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   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



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   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 . . . .   3
   4.  DNS privacy and outsourcing vs MUD controllers  . . . . . . .   3
   5.  Recommendations on MUD and DNS co-existence . . . . . . . . .   3
   6.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   3
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Appendix A.  Appendices . . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

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.

   At the MUD policy enforcement point - the firewall - there is a
   problem.  The firewall has only access to the layer-3 headers of the
   packet.  This includes the source and destination IP address, and if
   not encrypted by IPsec, the destination UDP or TCP port number
   present in the transport header.  The DNS name is not present!

   In order to implement this, there must be a mapping between the names
   in the ACLs and layer-3 IP addresses.  The first section of this
   document details a few strategies that are used.

   The second section of this document details how common manufacturer
   anti-patterns get in the way this mapping.



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   The third section of this document details how current trends in DNS
   resolution such as public DNS servers, DNS over TLS (DoT), and DNS
   over HTTPS (DoH) cause problems for the strategies employed.  Poor
   interactions with content-distribution networks is a frequent
   pathology that results.

   The fourth section of this document makes a series of recommendations
   ("best current practices") for manufacturers on how to use DNS, and
   IP addresses with specific purpose IoT devices.

   The Privacy Considerations section concerns itself with issues that
   DNS-over-TLS and DNS-over-HTTPS are frequently used to deal with.
   The question is how these concerns apply to IoT devices located
   within a residence or enterprise is dealt with.

   The Security Considerations section covers some of the negative
   outcomes should MUD/firewall managers and IoT manufacturers choose
   not to cooperate.

2.  Strategies to map names

   TBD

3.  DNS and IP Anti-Patterns for IoT device Manufacturers

   TBD

4.  DNS privacy and outsourcing vs MUD controllers

   TBD

5.  Recommendations on MUD and DNS co-existence

   TBD

6.  Privacy Considerations

   TBD

7.  Security Considerations

   TBD

8.  References







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8.1.  Normative References

   [RFC7858]  Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
              and P. Hoffman, "Specification for DNS over Transport
              Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
              2016, <https://www.rfc-editor.org/info/rfc7858>.

   [RFC8520]  Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage
              Description Specification", RFC 8520,
              DOI 10.17487/RFC8520, March 2019,
              <https://www.rfc-editor.org/info/rfc8520>.

8.2.  Informative References

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
              <https://www.rfc-editor.org/info/rfc1034>.

Appendix A.  Appendices

Author's Address

   Michael Richardson
   Sandelman Software Works

   Email: mcr+ietf@sandelman.ca

























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