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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 OPSAWG Working Group M. Richardson 3 Internet-Draft Sandelman Software Works 4 Intended status: Best Current Practice July 08, 2019 5 Expires: January 9, 2020 7 Operational Considerations for use of DNS in IoT devices 8 draft-richardson-opsawg-mud-iot-dns-considerations-00 10 Abstract 12 This document details concerns about how Internet of Things devices 13 use IP addresses and DNS names. The issue becomes acute as network 14 operators begin deploying RFC8520 Manufacturer Usage Description 15 (MUD) definitions to control device access. 17 This document explains the problem through a series of examples of 18 what can go wrong, and then provides some advice on how a device 19 manufacturer can best make deal with these issues. The 20 recommendations have an impact upon device and network protocol 21 design. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on January 9, 2020. 40 Copyright Notice 42 Copyright (c) 2019 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Strategies to map names . . . . . . . . . . . . . . . . . . . 3 59 3. DNS and IP Anti-Patterns for IoT device Manufacturers . . . . 3 60 4. DNS privacy and outsourcing vs MUD controllers . . . . . . . 3 61 5. Recommendations on MUD and DNS co-existence . . . . . . . . . 3 62 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 3 63 7. Security Considerations . . . . . . . . . . . . . . . . . . . 3 64 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 3 65 8.1. Normative References . . . . . . . . . . . . . . . . . . 4 66 8.2. Informative References . . . . . . . . . . . . . . . . . 4 67 Appendix A. Appendices . . . . . . . . . . . . . . . . . . . . . 4 68 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4 70 1. Introduction 72 [RFC8520] provides a standardized way to describe how a specific 73 purpose device makes use of Internet resources. Access Control Lists 74 (ACLs) can be defined in an RFC8520 Manufacturer Usage Description 75 (MUD) file that permit a device to access Internet resources by DNS 76 name. 78 Use of a DNS name rather than IP address in the ACL has many 79 advantages: not only does the layer of indirection permit the mapping 80 of name to IP address to be changed over time, it also generalizes 81 automatically to IPv4 and IPv6 addresses, as well as permitting 82 loading balancing of traffic by many different common ways, including 83 geography. 85 At the MUD policy enforcement point - the firewall - there is a 86 problem. The firewall has only access to the layer-3 headers of the 87 packet. This includes the source and destination IP address, and if 88 not encrypted by IPsec, the destination UDP or TCP port number 89 present in the transport header. The DNS name is not present! 91 In order to implement this, there must be a mapping between the names 92 in the ACLs and layer-3 IP addresses. The first section of this 93 document details a few strategies that are used. 95 The second section of this document details how common manufacturer 96 anti-patterns get in the way this mapping. 98 The third section of this document details how current trends in DNS 99 resolution such as public DNS servers, DNS over TLS (DoT), and DNS 100 over HTTPS (DoH) cause problems for the strategies employed. Poor 101 interactions with content-distribution networks is a frequent 102 pathology that results. 104 The fourth section of this document makes a series of recommendations 105 ("best current practices") for manufacturers on how to use DNS, and 106 IP addresses with specific purpose IoT devices. 108 The Privacy Considerations section concerns itself with issues that 109 DNS-over-TLS and DNS-over-HTTPS are frequently used to deal with. 110 The question is how these concerns apply to IoT devices located 111 within a residence or enterprise is dealt with. 113 The Security Considerations section covers some of the negative 114 outcomes should MUD/firewall managers and IoT manufacturers choose 115 not to cooperate. 117 2. Strategies to map names 119 TBD 121 3. DNS and IP Anti-Patterns for IoT device Manufacturers 123 TBD 125 4. DNS privacy and outsourcing vs MUD controllers 127 TBD 129 5. Recommendations on MUD and DNS co-existence 131 TBD 133 6. Privacy Considerations 135 TBD 137 7. Security Considerations 139 TBD 141 8. References 142 8.1. Normative References 144 [RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., 145 and P. Hoffman, "Specification for DNS over Transport 146 Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May 147 2016, . 149 [RFC8520] Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage 150 Description Specification", RFC 8520, 151 DOI 10.17487/RFC8520, March 2019, 152 . 154 8.2. Informative References 156 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 157 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 158 . 160 Appendix A. Appendices 162 Author's Address 164 Michael Richardson 165 Sandelman Software Works 167 Email: mcr+ietf@sandelman.ca