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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IPv6 maintenance Working Group (6man) F. Gont 3 Internet-Draft SI6 Networks / UTN-FRH 4 Updates: 2464, 2467, 2470, 2491, 2492, A. Cooper 5 2497, 2590, 3146, 3315, 3572, Cisco 6 4291, 4338, 4391, 5072, 5121 D. Thaler 7 (if approved) Microsoft 8 Intended status: Standards Track W. Liu 9 Expires: February 19, 2017 Huawei Technologies 10 August 18, 2016 12 Recommendation on Stable IPv6 Interface Identifiers 13 draft-ietf-6man-default-iids-14 15 Abstract 17 This document changes the recommended default IID generation scheme 18 for cases where SLAAC is used to generate a stable IPv6 address. It 19 recommends using the mechanism specified in RFC7217 in such cases, 20 and recommends against embedding stable link-layer addresses in IPv6 21 Interface Identifiers. It formally updates RFC2464, RFC2467, 22 RFC2470, RFC2491, RFC2492, RFC2497, RFC2590, RFC3146, RFC3572, 23 RFC4291, RFC4338, RFC4391, RFC5072, and RFC5121. This document does 24 not change any existing recommendations concerning the use of 25 temporary addresses as specified in RFC 4941. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at http://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on February 19, 2017. 44 Copyright Notice 46 Copyright (c) 2016 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (http://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 63 3. Generation of IPv6 Interface Identifiers with SLAAC . . . . . 4 64 4. Future Work . . . . . . . . . . . . . . . . . . . . . . . . . 4 65 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 66 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 67 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 68 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 71 1. Introduction 73 [RFC4862] specifies Stateless Address Autoconfiguration (SLAAC) for 74 IPv6 [RFC2460], which typically results in hosts configuring one or 75 more "stable" addresses composed of a network prefix advertised by a 76 local router, and an Interface Identifier (IID) [RFC4291] that 77 typically embeds a stable link-layer address (e.g., an IEEE LAN MAC 78 address). 80 In some network technologies and adaptation layers, the use of an IID 81 based on a link-layer address may offer some advantages. For 82 example, the IP-over-IEEE802.15.4 standard in [RFC6775] allows for 83 compression of IPv6 addresses when the IID is based on the underlying 84 link-layer address. 86 The security and privacy implications of embedding a stable link- 87 layer address in an IPv6 IID have been known for some time now, and 88 are discussed in great detail in [RFC7721]. They include: 90 o Network activity correlation 92 o Location tracking 94 o Address scanning 96 o Device-specific vulnerability exploitation 97 More generally, the reuse of identifiers that have their own 98 semantics or properties across different contexts or scopes can be 99 detrimental for security and privacy 100 [I-D.gont-predictable-numeric-ids]. In the case of traditional 101 stable IPv6 IIDs, some of the security and privacy implications are 102 dependent on the properties of the underlying link-layer addresses 103 (e.g., whether the link-layer address is ephemeral or randomly 104 generated), while other implications (e.g., reduction of the entropy 105 of the IID) depend on the algorithm for generating the IID itself. 106 In standardized recommendations for stable IPv6 IID generation meant 107 to achieve particular security and privacy properties, it is 108 therefore necessary to recommend against embedding stable link-layer 109 addresses in IPv6 IIDs. 111 Furthermore, some popular IPv6 implementations have already deviated 112 from the traditional stable IID generation scheme to mitigate the 113 aforementioned security and privacy implications [Microsoft]. 115 As a result of the aforementioned issues, this document changes the 116 recommended default IID generation scheme for generating stable IPv6 117 addresses with SLAAC to that specified in [RFC7217], and recommends 118 against embedding stable link-layer addresses in IPv6 Interface 119 Identifiers, such that the aforementioned issues are mitigated. That 120 is, this document simply replaces the default algorithm that is 121 recommended to be employed when generating stable IPv6 IIDs. 123 NOTE: [RFC4291] defines the "Modified EUI-64 format" for IIDs. 124 Appendix A of [RFC4291] then describes how to transform an IEEE 125 EUI-64 identifier, or an IEEE 802 48-bit MAC address from which an 126 EUI-64 identifier is derived, into an IID in the Modified EUI-64 127 format. 129 In a variety of scenarios, addresses that remain stable for the 130 lifetime of a host's connection to a single subnet, are viewed as 131 desirable. For example, stable addresses may be viewed as beneficial 132 for network management, event logging, enforcement of access control, 133 provision of quality of service, or for server or routing interfaces. 134 Similarly, stable addresses (as opposed to temporary addresses 135 [RFC4941]) allow for long-lived TCP connections, and are also usually 136 desirable when performing server-like functions (i.e., receiving 137 incoming connections). 139 The recommendations in this document apply only in cases where 140 implementations otherwise would have configured a stable IPv6 IID 141 containing a link layer address. For example, this document does not 142 change any existing recommendations concerning the use of temporary 143 addresses as specified in [RFC4941], nor do the recommendations apply 144 to cases where SLAAC is employed to generate non-stable IPv6 145 addresses (e.g. by embedding a link-layer address that is 146 periodically randomized), nor does it introduce any new requirements 147 regarding when stable addresses are to be configured. Thus, the 148 recommendations in this document simply improve the security and 149 privacy properties of stable addresses. 151 2. Terminology 153 Stable address: 154 An address that does not vary over time within the same network 155 (as defined in [RFC7721]). 157 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 158 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 159 document are to be interpreted as described in RFC 2119 [RFC2119]. 161 3. Generation of IPv6 Interface Identifiers with SLAAC 163 Nodes SHOULD implement and employ [RFC7217] as the default scheme for 164 generating stable IPv6 addresses with SLAAC. A link layer MAY also 165 define a mechanism for stable IPv6 address generation that is more 166 efficient and does not address the security and privacy 167 considerations discussed in Section 1. The choice of whether to 168 enable the security- and privacy-preserving mechanism or not SHOULD 169 be configurable in such a case. 171 By default, nodes SHOULD NOT employ IPv6 address generation schemes 172 that embed a stable link-layer address in the IID. In particular, 173 this document RECOMMENDS that nodes do not generate stable IIDs with 174 the schemes specified in [RFC2464], [RFC2467], [RFC2470], [RFC2491], 175 [RFC2492], [RFC2497], [RFC2590], [RFC3146], [RFC3572], [RFC4338], 176 [RFC4391], [RFC5121], and [RFC5072]. 178 4. Future Work 180 At the time of this writing, the mechanisms specified in the 181 following documents might require updates to be fully compatible with 182 the recommendations in this document: 184 o "Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based 185 Networks" [RFC6282] 187 o "Transmission of IPv6 Packets over IEEE 802.15.4 Networks" 188 [RFC4944] 190 o "Neighbor Discovery Optimization for IPv6 over Low-Power Wireless 191 Personal Area Networks (6LoWPANs)"[RFC6775] 193 o "Transmission of IPv6 Packets over ITU-T G.9959 Networks"[RFC7428] 195 Future revisions or updates of these documents should take the issues 196 of privacy and security mentioned in Section 1 and explain any design 197 and engineering considerations that lead to the use of stable IIDs 198 based on a node's link-layer address. 200 5. IANA Considerations 202 There are no IANA registries within this document. The RFC-Editor 203 can remove this section before publication of this document as an 204 RFC. 206 6. Security Considerations 208 This recommends against the (default) use of predictable Interface 209 Identifiers in IPv6 addresses. It recommends [RFC7217] as the 210 default scheme for generating IPv6 stable addresses with SLAAC, such 211 that the security and privacy issues of IIDs that embed stable link- 212 layer addresses are mitigated. 214 7. Acknowledgements 216 The authors would like to thank (in alphabetical order) Bob Hinden, 217 Ray Hunter and Erik Nordmark, for providing a detailed review of this 218 document. 220 The authors would like to thank (in alphabetical order) Fred Baker, 221 Carsten Bormann, Scott Brim, Brian Carpenter, Samita Chakrabarti, Tim 222 Chown, Lorenzo Colitti, Jean-Michel Combes, Greg Daley, Esko Dijk, 223 Ralph Droms, David Farmer, Brian Haberman, Ulrich Herberg, Philip 224 Homburg, Jahangir Hossain, Jonathan Hui, Christian Huitema, Ray 225 Hunter, Erik Kline, Sheng Jiang, Roger Jorgensen, Dan Luedtke, Kerry 226 Lynn, George Mitchel, Gabriel Montenegro, Erik Nordmark, Simon 227 Perreault, Tom Petch, Alexandru Petrescu, Michael Richardson, Arturo 228 Servin, Mark Smith, Tom Taylor, Ole Troan, Tina Tsou, Glen Turner, 229 Randy Turner, James Woodyatt, and Juan Carlos Zuniga, for providing 230 valuable comments on earlier versions of this document. 232 8. References 234 8.1. Normative References 236 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 237 Requirement Levels", BCP 14, RFC 2119, 238 DOI 10.17487/RFC2119, March 1997, 239 . 241 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 242 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 243 December 1998, . 245 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 246 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 247 . 249 [RFC2467] Crawford, M., "Transmission of IPv6 Packets over FDDI 250 Networks", RFC 2467, DOI 10.17487/RFC2467, December 1998, 251 . 253 [RFC2470] Crawford, M., Narten, T., and S. Thomas, "Transmission of 254 IPv6 Packets over Token Ring Networks", RFC 2470, 255 DOI 10.17487/RFC2470, December 1998, 256 . 258 [RFC2491] Armitage, G., Schulter, P., Jork, M., and G. Harter, "IPv6 259 over Non-Broadcast Multiple Access (NBMA) networks", 260 RFC 2491, DOI 10.17487/RFC2491, January 1999, 261 . 263 [RFC2492] Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM 264 Networks", RFC 2492, DOI 10.17487/RFC2492, January 1999, 265 . 267 [RFC2497] Souvatzis, I., "Transmission of IPv6 Packets over ARCnet 268 Networks", RFC 2497, DOI 10.17487/RFC2497, January 1999, 269 . 271 [RFC2590] Conta, A., Malis, A., and M. Mueller, "Transmission of 272 IPv6 Packets over Frame Relay Networks Specification", 273 RFC 2590, DOI 10.17487/RFC2590, May 1999, 274 . 276 [RFC3146] Fujisawa, K. and A. Onoe, "Transmission of IPv6 Packets 277 over IEEE 1394 Networks", RFC 3146, DOI 10.17487/RFC3146, 278 October 2001, . 280 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 281 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 282 2006, . 284 [RFC4338] DeSanti, C., Carlson, C., and R. Nixon, "Transmission of 285 IPv6, IPv4, and Address Resolution Protocol (ARP) Packets 286 over Fibre Channel", RFC 4338, DOI 10.17487/RFC4338, 287 January 2006, . 289 [RFC4391] Chu, J. and V. Kashyap, "Transmission of IP over 290 InfiniBand (IPoIB)", RFC 4391, DOI 10.17487/RFC4391, April 291 2006, . 293 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 294 Address Autoconfiguration", RFC 4862, 295 DOI 10.17487/RFC4862, September 2007, 296 . 298 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 299 Extensions for Stateless Address Autoconfiguration in 300 IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007, 301 . 303 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 304 "Transmission of IPv6 Packets over IEEE 802.15.4 305 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 306 . 308 [RFC5072] Varada, S., Ed., Haskins, D., and E. Allen, "IP Version 6 309 over PPP", RFC 5072, DOI 10.17487/RFC5072, September 2007, 310 . 312 [RFC5121] Patil, B., Xia, F., Sarikaya, B., Choi, JH., and S. 313 Madanapalli, "Transmission of IPv6 via the IPv6 314 Convergence Sublayer over IEEE 802.16 Networks", RFC 5121, 315 DOI 10.17487/RFC5121, February 2008, 316 . 318 [RFC5453] Krishnan, S., "Reserved IPv6 Interface Identifiers", 319 RFC 5453, DOI 10.17487/RFC5453, February 2009, 320 . 322 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 323 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 324 DOI 10.17487/RFC6282, September 2011, 325 . 327 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 328 Bormann, "Neighbor Discovery Optimization for IPv6 over 329 Low-Power Wireless Personal Area Networks (6LoWPANs)", 330 RFC 6775, DOI 10.17487/RFC6775, November 2012, 331 . 333 [RFC7217] Gont, F., "A Method for Generating Semantically Opaque 334 Interface Identifiers with IPv6 Stateless Address 335 Autoconfiguration (SLAAC)", RFC 7217, 336 DOI 10.17487/RFC7217, April 2014, 337 . 339 [RFC7428] Brandt, A. and J. Buron, "Transmission of IPv6 Packets 340 over ITU-T G.9959 Networks", RFC 7428, 341 DOI 10.17487/RFC7428, February 2015, 342 . 344 8.2. Informative References 346 [I-D.gont-predictable-numeric-ids] 347 Gont, F. and I. Arce, "Security and Privacy Implications 348 of Numeric Identifiers Employed in Network Protocols", 349 draft-gont-predictable-numeric-ids-00 (work in progress), 350 February 2016. 352 [IANA-RESERVED-IID] 353 IANA, "Reserved IPv6 Interface Identifiers", 354 . 356 [Microsoft] 357 Davies, J., "Understanding IPv6, 3rd. ed", page 83, 358 Microsoft Press, 2012, . 360 [RFC3572] Ogura, T., Maruyama, M., and T. Yoshida, "Internet 361 Protocol Version 6 over MAPOS (Multiple Access Protocol 362 Over SONET/SDH)", RFC 3572, DOI 10.17487/RFC3572, July 363 2003, . 365 [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy 366 Considerations for IPv6 Address Generation Mechanisms", 367 RFC 7721, DOI 10.17487/RFC7721, March 2016, 368 . 370 Authors' Addresses 372 Fernando Gont 373 SI6 Networks / UTN-FRH 374 Evaristo Carriego 2644 375 Haedo, Provincia de Buenos Aires 1706 376 Argentina 378 Phone: +54 11 4650 8472 379 Email: fgont@si6networks.com 380 URI: http://www.si6networks.com 381 Alissa Cooper 382 Cisco 383 707 Tasman Drive 384 Milpitas, CA 95035 385 US 387 Phone: +1-408-902-3950 388 Email: alcoop@cisco.com 389 URI: https://www.cisco.com/ 391 Dave Thaler 392 Microsoft 393 Microsoft Corporation 394 One Microsoft Way 395 Redmond, WA 98052 397 Phone: +1 425 703 8835 398 Email: dthaler@microsoft.com 400 Will Liu 401 Huawei Technologies 402 Bantian, Longgang District 403 Shenzhen 518129 404 P.R. China 406 Email: liushucheng@huawei.com