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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (February 27, 2017) is 2616 days in the past. Is this intentional? Checking references for intended status: Best Current Practice ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 3315 (Obsoleted by RFC 8415) ** Obsolete normative reference: RFC 6106 (Obsoleted by RFC 8106) Summary: 2 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IPv6 Operations Working Group (v6ops) F. Gont 3 Internet-Draft SI6 Networks / UTN-FRH 4 Intended status: Best Current Practice G. Doering 5 Expires: August 31, 2017 SpaceNet AG 6 M. Garcia Corbo 7 SITRANS 8 G. Gont 9 SI6 Networks 10 February 27, 2017 12 On the Dynamic/Automatic Configuration of IPv6 Hosts 13 draft-gont-v6ops-host-configuration-00 15 Abstract 17 IPv6 has two different mechanisms for dynamic/automatic host 18 configuration: SLAAC and DHCPv6. These two mechanisms allow for the 19 configuration of IPv6 addresses and a number of network parameters. 20 While there is overlap in the parameters that can be configured via 21 these two protocols, different implementations support only subsets 22 of such parameters with either mechanism, or have no support for 23 DHCPv6 at all. This document analyzes a problem that arises from 24 this situation, and mandates that all host implementations support 25 RFC 6105 (DNS options for SLAAC) and the stateless DHCPv6 26 functionality in RFC 3315. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at http://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on August 31, 2017. 45 Copyright Notice 47 Copyright (c) 2017 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 This document may not be modified, and derivative works of it may not 61 be created, and it may not be published except as an Internet-Draft. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 66 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 67 3. Requirements for IPv6 Hosts . . . . . . . . . . . . . . . . . 4 68 4. Requirements for IPv6 Routers . . . . . . . . . . . . . . . . 4 69 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 70 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 71 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 72 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 73 8.1. Normative References . . . . . . . . . . . . . . . . . . 4 74 8.2. Informative References . . . . . . . . . . . . . . . . . 5 75 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 77 1. Introduction 79 IPv6 has two different mechanisms for dynamic/automatic host 80 configuration: Stateless Address Autoconfiguration (SLAAC) [RFC4862] 81 and Dynamic Host Configuration Protocol for IPv6 (DHCPv6) [RFC3315]. 82 SLAAC allows for distributed address assignment (where each host 83 automatically configures its own IPv6 addresses) and basic network 84 configuration (such as recursive DNS servers and DNS search lists). 85 On the other hand, DHCPv6 provides for centralized address assignment 86 (the DHCPv6 server leases IPv6 addresses to hosts) and richer network 87 configuration (NTP servers, web proxys, etc.). 89 Traditionally, SLAAC has been seen as a more lightweight mechanism, 90 suitable for resource-constrained devices, while DHCPv6 has been seen 91 more as heavy-weight and full-fledged mechanism. We note that this 92 distinction is rather questionable, and is essentially meaningless 93 for typical mobile devices or home appliances. 95 Among the possible configuration information that can be conveyed 96 with both SLAAC and DHCPv6 is DNS related configuration: recursive 97 DNS servers and DNS search lists. Configuring this information is 98 probably as vital in practice as configuring IPv6 addresses, since 99 for obvious reasons both humans and popular applications operate on 100 names (rather than on IPv6 addresses). The ability to convey this 101 information has always been part of DHCPv6, while for the SLAAC case, 102 support was added in a separate document that standardizes "IPv6 103 Router Advertisement Options for DNS Configuration" [RFC6106]. 105 Unfortunately, different host and router implementations provide 106 support for only a subset of these options. For example, some host 107 implementations (e.g., Android) support SLAAC DNS options [RFC6106], 108 but do not support stateless DHCPv6. On the other hand, other host 109 implementations (e.g., Microsoft Windows) support stateless DHCPv6, 110 but do not support [RFC6106]. Similarly, some router implementations 111 support [RFC6106], while others do not. 113 This represents a problem for IPv6 deployment, since: 115 1. in order to support most popular IPv6 host implementations, IPv6 116 networks are required to support *both* SLAAC and DHCPv6. 118 2. some router implementations do not support [RFC6106] and hence 119 support for the SLAAC DNS options may be impossible or require 120 yet an additional network element or network service to support 121 [RFC6106] 123 We note that, in most cases, this problem is currently masked by the 124 fact that most IPv6 deployments are actually dual-stack, and hence 125 hosts can currently rely DNS-related information being obtained via 126 IPv4-based DHCP. However, at the point such deployments disable IPv4 127 to become IPv6-only, the aforementioned problems will become evident, 128 possibly as a surprise to network operators. 130 2. Terminology 132 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 133 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 134 document are to be interpreted as described in RFC 2119 [RFC2119]. 136 3. Requirements for IPv6 Hosts 138 IPv6 hosts MUST support the SLAAC DNS options specified in [RFC6106], 139 and the stateless DHCPv6 mechanism specified in [RFC3315]. 141 4. Requirements for IPv6 Routers 143 IPv6 routers MUST support the SLAAC DNS options specified in 144 [RFC6106]. 146 5. IANA Considerations 148 This document has no actions for IANA. The RFC-Editor should remove 149 this section prior to publication of this document as an RFC. 151 6. Security Considerations 153 Host implementations supporting SLAAC are subject to a number of 154 attacks based on forged ICMPv6 Router Advertisement [RFC4861] 155 messages. Such attacks can be mitigated by means of RA-Guard 156 [RFC6105] [RFC7113]. Hosts supporting DHCPv6 are subject to a number 157 of attacks based on forged DHCPv6-server messages. Such attacks can 158 be mitigated by means of DHCPv6-Shield [RFC7610]. 160 7. Acknowledgements 162 The authors would like to thank Brian Carpenter for providing 163 valuable comments on earlier versions of this document. 165 Fernando Gont would like to thank Nelida Garcia and Jorge Oscar Gont 166 for their love and support, and Ivan Arce and Diego Armando Maradona 167 for their inspiration. 169 8. References 171 8.1. Normative References 173 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 174 Requirement Levels", BCP 14, RFC 2119, 175 DOI 10.17487/RFC2119, March 1997, 176 . 178 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 179 C., and M. Carney, "Dynamic Host Configuration Protocol 180 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 181 2003, . 183 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 184 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 185 DOI 10.17487/RFC4861, September 2007, 186 . 188 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 189 Address Autoconfiguration", RFC 4862, 190 DOI 10.17487/RFC4862, September 2007, 191 . 193 [RFC6106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, 194 "IPv6 Router Advertisement Options for DNS Configuration", 195 RFC 6106, DOI 10.17487/RFC6106, November 2010, 196 . 198 8.2. Informative References 200 [RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J. 201 Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105, 202 DOI 10.17487/RFC6105, February 2011, 203 . 205 [RFC7113] Gont, F., "Implementation Advice for IPv6 Router 206 Advertisement Guard (RA-Guard)", RFC 7113, 207 DOI 10.17487/RFC7113, February 2014, 208 . 210 [RFC7610] Gont, F., Liu, W., and G. Van de Velde, "DHCPv6-Shield: 211 Protecting against Rogue DHCPv6 Servers", BCP 199, 212 RFC 7610, DOI 10.17487/RFC7610, August 2015, 213 . 215 Authors' Addresses 217 Fernando Gont 218 SI6 Networks / UTN-FRH 219 Evaristo Carriego 2644 220 Haedo, Provincia de Buenos Aires 1706 221 Argentina 223 Phone: +54 11 4650 8472 224 Email: fgont@si6networks.com 225 URI: http://www.si6networks.com 226 Gert Doering 227 SpaceNet AG 228 Joseph-Dollinger-Bogen 14 229 Muenchen D-80807 230 Germany 232 Email: gert@space.net 234 Madelen Garcia Corbo 235 Servicios de Informacion del Transporte 236 Neptuno 358 237 Havana City 10400 238 Cuba 240 Email: madelen.garcia16@gmail.com 242 Guillermo Gont 243 SI6 Networks 244 Evaristo Carriego 2644 245 Haedo, Provincia de Buenos Aires 1706 246 Argentina 248 Phone: +54 11 4650 8472 249 Email: ggont@si6networks.com 250 URI: https://www.si6networks.com