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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group J. Laganier 3 Internet-Draft Luminate Wireless, Inc. 4 Obsoletes: 5205 (if approved) December 11, 2013 5 Intended status: Standards Track 6 Expires: June 14, 2014 8 Host Identity Protocol (HIP) Domain Name System (DNS) Extension 9 draft-ietf-hip-rfc5205-bis-03 11 Abstract 13 This document specifies a new resource record (RR) for the Domain 14 Name System (DNS), and how to use it with the Host Identity Protocol 15 (HIP). This RR allows a HIP node to store in the DNS its Host 16 Identity (HI, the public component of the node public-private key 17 pair), Host Identity Tag (HIT, a truncated hash of its public key), 18 and the Domain Names of its rendezvous servers (RVSs). This document 19 obsoletes RFC5205. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on June 14, 2014. 38 Copyright Notice 40 Copyright (c) 2013 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 57 3. Usage Scenarios . . . . . . . . . . . . . . . . . . . . . . . 3 58 3.1. Simple Static Singly Homed End-Host . . . . . . . . . . . 5 59 3.2. Mobile end-host . . . . . . . . . . . . . . . . . . . . . 6 60 4. Overview of Using the DNS with HIP . . . . . . . . . . . . . 7 61 4.1. Storing HI, HIT, and RVS in the DNS . . . . . . . . . . . 8 62 4.2. Initiating Connections Based on DNS Names . . . . . . . . 8 63 5. HIP RR Storage Format . . . . . . . . . . . . . . . . . . . . 9 64 5.1. HIT Length Format . . . . . . . . . . . . . . . . . . . . 9 65 5.2. PK Algorithm Format . . . . . . . . . . . . . . . . . . . 9 66 5.3. PK Length Format . . . . . . . . . . . . . . . . . . . . 10 67 5.4. HIT Format . . . . . . . . . . . . . . . . . . . . . . . 10 68 5.5. Public Key Format . . . . . . . . . . . . . . . . . . . . 10 69 5.6. Rendezvous Servers Format . . . . . . . . . . . . . . . . 10 70 6. HIP RR Presentation Format . . . . . . . . . . . . . . . . . 10 71 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 11 72 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 73 8.1. Attacker Tampering with an Insecure HIP RR . . . . . . . 12 74 8.2. Hash and HITs Collisions . . . . . . . . . . . . . . . . 13 75 8.3. DNSSEC . . . . . . . . . . . . . . . . . . . . . . . . . 13 76 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 77 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 14 78 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 79 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 80 12.1. Normative references . . . . . . . . . . . . . . . . . . 14 81 12.2. Informative references . . . . . . . . . . . . . . . . . 15 82 Appendix A. Changes from RFC 5205 . . . . . . . . . . . . . . . 15 84 1. Introduction 86 This document specifies a new resource record (RR) for the Domain 87 Name System (DNS) [RFC1034], and how to use it with the Host Identity 88 Protocol (HIP) [I-D.ietf-hip-rfc5201-bis]. This RR allows a HIP node 89 to store in the DNS its Host Identity (HI, the public component of 90 the node public-private key pair), Host Identity Tag (HIT, a 91 truncated hash of its HI), and the Domain Names of its rendezvous 92 servers (RVSs) [I-D.ietf-hip-rfc5204-bis]. 94 Currently, most of the Internet applications that need to communicate 95 with a remote host first translate a domain name (often obtained via 96 user input) into one or more IP address(es). This step occurs prior 97 to communication with the remote host, and relies on a DNS lookup. 99 With HIP, IP addresses are intended to be used mostly for on-the-wire 100 communication between end hosts, while most Upper Layer Protocols 101 (ULP) and applications use HIs or HITs instead (ICMP might be an 102 example of an ULP not using them). Consequently, we need a means to 103 translate a domain name into an HI. Using the DNS for this 104 translation is pretty straightforward: We define a new HIP resource 105 record. Upon query by an application or ULP for a name to IP address 106 lookup, the resolver would then additionally perform a name to HI 107 lookup, and use it to construct the resulting HI to IP address 108 mapping (which is internal to the HIP layer). The HIP layer uses the 109 HI to IP address mapping to translate HIs and HITs into IP addresses 110 and vice versa. 112 The HIP Rendezvous Extension [I-D.ietf-hip-rfc5204-bis] allows a HIP 113 node to be reached via the IP address(es) of a third party, the 114 node's rendezvous server (RVS). An Initiator willing to establish a 115 HIP association with a Responder served by an RVS would typically 116 initiate a HIP exchange by sending an I1 towards the RVS IP address 117 rather than towards the Responder IP address. Consequently, we need 118 a means to find the name of a rendezvous server for a given host 119 name. 121 This document introduces the new HIP DNS resource record to store the 122 Rendezvous Server (RVS), Host Identity (HI), and Host Identity Tag 123 (HIT) information. 125 2. Conventions Used in This Document 127 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 128 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 129 document are to be interpreted as described in RFC 2119 [RFC2119]. 131 3. Usage Scenarios 133 In this section, we briefly introduce a number of usage scenarios 134 where the DNS is useful with the Host Identity Protocol. 136 With HIP, most applications and ULPs are unaware of the IP addresses 137 used to carry packets on the wire. Consequently, a HIP node could 138 take advantage of having multiple IP addresses for fail-over, 139 redundancy, mobility, or renumbering, in a manner that is transparent 140 to most ULPs and applications (because they are bound to HIs; hence, 141 they are agnostic to these IP address changes). 143 In these situations, for a node to be reachable by reference to its 144 Fully Qualified Domain Name (FQDN), the following information should 145 be stored in the DNS: 147 o A set of IP address(es) via A [RFC1035] and AAAA [RFC3596] RR sets 148 (RRSets [RFC2181]). 150 o A Host Identity (HI), Host Identity Tag (HIT), and possibly a set 151 of rendezvous servers (RVS) through HIP RRs. 153 The HIP RR is class independent. 155 When a HIP node wants to initiate communication with another HIP 156 node, it first needs to perform a HIP base exchange to set up a HIP 157 association towards its peer. Although such an exchange can be 158 initiated opportunistically, i.e., without prior knowledge of the 159 Responder's HI, by doing so both nodes knowingly risk man-in-the- 160 middle attacks on the HIP exchange. To prevent these attacks, it is 161 recommended that the Initiator first obtain the HI of the Responder, 162 and then initiate the exchange. This can be done, for example, 163 through manual configuration or DNS lookups. Hence, a new HIP RR is 164 introduced. 166 When a HIP node is frequently changing its IP address(es), the 167 natural DNS latency for propagating changes may prevent it from 168 publishing its new IP address(es) in the DNS. For solving this 169 problem, the HIP Architecture [RFC4423] introduces rendezvous servers 170 (RVSs) [I-D.ietf-hip-rfc5204-bis]. A HIP host uses a rendezvous 171 server as a rendezvous point to maintain reachability with possible 172 HIP initiators while moving [RFC5206]. Such a HIP node would publish 173 in the DNS its RVS domain name(s) in a HIP RR, while keeping its RVS 174 up-to-date with its current set of IP addresses. 176 When a HIP node wants to initiate a HIP exchange with a Responder, it 177 will perform a number of DNS lookups. Depending on the type of 178 implementation, the order in which those lookups will be issued may 179 vary. For instance, implementations using HIT in APIs may typically 180 first query for HIP resource records at the Responder FQDN, while 181 those using an IP address in APIs may typically first query for A and 182 /or AAAA resource records. 184 In the following, we assume that the Initiator first queries for HIP 185 resource records at the Responder FQDN. 187 If the query for the HIP type was responded to with a DNS answer with 188 RCODE=3 (Name Error), then the Responder's information is not present 189 in the DNS and further queries for the same owner name SHOULD NOT be 190 made. 192 In case the query for the HIP records returned a DNS answer with 193 RCODE=0 (No Error) and an empty answer section, it means that no HIP 194 information is available at the responder name. In such a case, if 195 the Initiator has been configured with a policy to fallback to 196 opportunistic HIP (initiating without knowing the Responder's HI) or 197 plain IP, it would send out more queries for A and AAAA types at the 198 Responder's FQDN. 200 Depending on the combinations of answers, the situations described in 201 Section 3.1 and Section 3.2 can occur. 203 Note that storing HIP RR information in the DNS at an FQDN that is 204 assigned to a non-HIP node might have ill effects on its reachability 205 by HIP nodes. 207 3.1. Simple Static Singly Homed End-Host 209 A HIP node (R) with a single static network attachment, wishing to be 210 reachable by reference to its FQDN (www.example.com), would store in 211 the DNS, in addition to its IP address(es) (IP-R), its Host Identity 212 (HI-R) and Host Identity Tag (HIT-R) in a HIP resource record. 214 An Initiator willing to associate with a node would typically issue 215 the following queries: 217 o QNAME=www.example.com, QTYPE=HIP 219 o (QCLASS=IN is assumed and omitted from the examples) 221 Which returns a DNS packet with RCODE=0 and one or more HIP RRs with 222 the HIT and HI (e.g., HIT-R and HI-R) of the Responder in the answer 223 section, but no RVS. 225 o QNAME=www.example.com, QTYPE=A QNAME=www.example.com, QTYPE=AAAA 227 Which returns DNS packets with RCODE=0 and one or more A or AAAA RRs 228 containing IP address(es) of the Responder (e.g., IP-R) in the answer 229 section. 231 Caption: In the remainder of this document, for the sake of keeping 232 diagrams simple and concise, several DNS queries and answers 233 are represented as one single transaction, while in fact 234 there are several queries and answers flowing back and 235 forth, as described in the textual examples. 237 [HIP? A? ] 238 [www.example.com] +-----+ 239 +-------------------------------->| | 240 | | DNS | 241 | +-------------------------------| | 242 | | [HIP? A? ] +-----+ 243 | | [www.example.com] 244 | | [HIP HIT-R HI-R ] 245 | | [A IP-R ] 246 | v 247 +-----+ +-----+ 248 | |--------------I1------------->| | 249 | I |<-------------R1--------------| R | 250 | |--------------I2------------->| | 251 | |<-------------R2--------------| | 252 +-----+ +-----+ 254 Static Singly Homed Host 256 The Initiator would then send an I1 to the Responder's IP addresses 257 (IP-R). 259 3.2. Mobile end-host 261 A mobile HIP node (R) wishing to be reachable by reference to its 262 FQDN (www.example.com) would store in the DNS, possibly in addition 263 to its IP address(es) (IP-R), its HI (HI-R), HIT (HIT-R), and the 264 domain name(s) of its rendezvous server(s) (e.g., rvs.example.com) in 265 HIP resource record(s). The mobile HIP node also needs to notify its 266 rendezvous servers of any change in its set of IP address(es). 268 An Initiator willing to associate with such a mobile node would 269 typically issue the following queries: 271 o QNAME=www.example.com, QTYPE=HIP 273 Which returns a DNS packet with RCODE=0 and one or more HIP RRs with 274 the HIT, HI, and RVS domain name(s) (e.g., HIT-R, HI-R, and 275 rvs.example.com) of the Responder in the answer section. 277 o QNAME=rvs.example.com, QTYPE=A QNAME=www.example.com, QTYPE=AAAA 278 Which returns DNS packets with RCODE=0 and one or more A or AAAA RRs 279 containing IP address(es) of the Responder's RVS (e.g., IP-RVS) in 280 the answer section. 282 [HIP? ] 283 [www.example.com] 285 [A? ] 286 [rvs.example.com] +-----+ 287 +----------------------------------------->| | 288 | | DNS | 289 | +----------------------------------------| | 290 | | [HIP? ] +-----+ 291 | | [www.example.com ] 292 | | [HIP HIT-R HI-R rvs.example.com] 293 | | 294 | | [A? ] 295 | | [rvs.example.com] 296 | | [A IP-RVS ] 297 | | 298 | | +-----+ 299 | | +------I1----->| RVS |-----I1------+ 300 | | | +-----+ | 301 | | | | 302 | | | | 303 | v | v 304 +-----+ +-----+ 305 | |<---------------R1------------| | 306 | I |----------------I2----------->| R | 307 | |<---------------R2------------| | 308 +-----+ +-----+ 310 Mobile End-Host 312 The Initiator would then send an I1 to the RVS IP address (IP-RVS). 313 Following, the RVS will relay the I1 up to the mobile node's IP 314 address (IP-R), which will complete the HIP exchange. 316 4. Overview of Using the DNS with HIP 317 4.1. Storing HI, HIT, and RVS in the DNS 319 For any HIP node, its Host Identity (HI), the associated Host 320 Identity Tag (HIT), and the FQDN of its possible RVSs can be stored 321 in a DNS HIP RR. Any conforming implementation may store a Host 322 Identity (HI) and its associated Host Identity Tag (HIT) in a DNS HIP 323 RDATA format. HI and HIT are defined in Section 3 of the HIP 324 specification [I-D.ietf-hip-rfc5201-bis]. 326 Upon return of a HIP RR, a host MUST always calculate the HI- 327 derivative HIT to be used in the HIP exchange, as specified in 328 Section 3 of the HIP specification [I-D.ietf-hip-rfc5201-bis], while 329 the HIT possibly embedded along SHOULD only be used as an 330 optimization (e.g., table lookup). 332 The HIP resource record may also contain one or more domain name(s) 333 of rendezvous server(s) towards which HIP I1 packets might be sent to 334 trigger the establishment of an association with the entity named by 335 this resource record [I-D.ietf-hip-rfc5204-bis]. 337 The rendezvous server field of the HIP resource record stored at a 338 given owner name MAY include the owner name itself. A semantically 339 equivalent situation occurs if no rendezvous server is present in the 340 HIP resource record stored at that owner name. Such situations occur 341 in two cases: 343 o The host is mobile, and the A and/or AAAA resource record(s) 344 stored at its host name contain the IP address(es) of its 345 rendezvous server rather than its own one. 347 o The host is stationary, and can be reached directly at the IP 348 address(es) contained in the A and/or AAAA resource record(s) 349 stored at its host name. This is a degenerated case of rendezvous 350 service where the host somewhat acts as a rendezvous server for 351 itself. 353 An RVS receiving such an I1 would then relay it to the appropriate 354 Responder (the owner of the I1 receiver HIT). The Responder will 355 then complete the exchange with the Initiator, typically without 356 ongoing help from the RVS. 358 4.2. Initiating Connections Based on DNS Names 360 On a HIP node, a Host Identity Protocol exchange SHOULD be initiated 361 whenever a ULP attempts to communicate with an entity and the DNS 362 lookup returns HIP resource records. 364 5. HIP RR Storage Format 366 The RDATA for a HIP RR consists of a public key algorithm type, the 367 HIT length, a HIT, a public key, and optionally one or more 368 rendezvous server(s). 370 0 1 2 3 371 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 372 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 373 | HIT length | PK algorithm | PK length | 374 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 375 | | 376 ~ HIT ~ 377 | | 378 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 379 | | | 380 +-+-+-+-+-+-+-+-+-+-+-+ + 381 | Public Key | 382 ~ ~ 383 | | 384 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 385 | | | 386 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + 387 | | 388 ~ Rendezvous Servers ~ 389 | | 390 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 391 | | 392 +-+-+-+-+-+-+-+ 394 The HIT length, PK algorithm, PK length, HIT, and Public Key fields 395 are REQUIRED. The Rendezvous Servers field is OPTIONAL. 397 5.1. HIT Length Format 399 The HIT length indicates the length in bytes of the HIT field. This 400 is an 8-bit unsigned integer. 402 5.2. PK Algorithm Format 404 The PK algorithm field indicates the public key cryptographic 405 algorithm and the implied public key field format. This is an 8-bit 406 unsigned integer. This document reuses the values defined for the 407 'algorithm type' of the IPSECKEY RR [RFC4025]. 409 Presently defined values are listed in Section 9 for reference. 411 5.3. PK Length Format 413 The PK length indicates the length in bytes of the Public key field. 414 This is a 16-bit unsigned integer in network byte order. 416 5.4. HIT Format 418 The HIT is stored as a binary value in network byte order. 420 5.5. Public Key Format 422 Both of the public key types defined in this document (RSA and DSA) 423 reuse the public key formats defined for the IPSECKEY RR [RFC4025]. 425 The DSA key format is defined in RFC 2536 [RFC2536]. 427 The RSA key format is defined in RFC 3110 [RFC3110] and the RSA key 428 size limit (4096 bits) is relaxed in the IPSECKEY RR [RFC4025] 429 specification. 431 5.6. Rendezvous Servers Format 433 The Rendezvous Servers field indicates one or more variable length 434 wire-encoded domain names of rendezvous server(s), as described in 435 Section 3.3 of RFC 1035 [RFC1035]. The wire-encoded format is self- 436 describing, so the length is implicit. The domain names MUST NOT be 437 compressed. The rendezvous server(s) are listed in order of 438 preference (i.e., first rendezvous server(s) are preferred), defining 439 an implicit order amongst rendezvous servers of a single RR. When 440 multiple HIP RRs are present at the same owner name, this implicit 441 order of rendezvous servers within an RR MUST NOT be used to infer a 442 preference order between rendezvous servers stored in different RRs. 444 6. HIP RR Presentation Format 446 This section specifies the representation of the HIP RR in a zone 447 master file. 449 The HIT length field is not represented, as it is implicitly known 450 thanks to the HIT field representation. 452 The PK algorithm field is represented as unsigned integers. 454 The HIT field is represented as the Base16 encoding [RFC4648] (a.k.a. 455 hex or hexadecimal) of the HIT. The encoding MUST NOT contain 456 whitespaces to distinguish it from the public key field. 458 The Public Key field is represented as the Base64 encoding [RFC4648] 459 of the public key. The encoding MUST NOT contain whitespace(s) to 460 distinguish it from the Rendezvous Servers field. 462 The PK length field is not represented, as it is implicitly known 463 thanks to the Public key field representation containing no 464 whitespaces. 466 The Rendezvous Servers field is represented by one or more domain 467 name(s) separated by whitespace(s). 469 The complete representation of the HPIHI record is: 471 IN HIP ( pk-algorithm 472 base16-encoded-hit 473 base64-encoded-public-key 474 rendezvous-server[1] 475 ... 476 rendezvous-server[n] ) 478 When no RVSs are present, the representation of the HPIHI record is: 480 IN HIP ( pk-algorithm 481 base16-encoded-hit 482 base64-encoded-public-key ) 484 7. Examples 486 In the examples below, the public key field containing no whitespace 487 is wrapped since it does not fit in a single line of this document. 489 Example of a node with HI and HIT but no RVS: 491 www.example.com. IN HIP ( 2 200100107B1A74DF365639CC39F1D578 492 AwEAAbdxyhNuSutc5EMzxTs9LBPCIkOFH8cIvM4p 493 9+LrV4e19WzK00+CI6zBCQTdtWsuxKbWIy87UOoJTwkUs7lBu+Upr1gsNrut79ryra+bSRGQ 494 b1slImA8YVJyuIDsj7kwzG7jnERNqnWxZ48AWkskmdHaVDP4BcelrTI3rMXdXF5D ) 496 Example of a node with a HI, HIT, and one RVS: 498 www.example.com. IN HIP ( 2 200100107B1A74DF365639CC39F1D578 499 AwEAAbdxyhNuSutc5EMzxTs9LBPCIkOFH8cIvM4p 500 9+LrV4e19WzK00+CI6zBCQTdtWsuxKbWIy87UOoJTwkUs7lBu+Upr1gsNrut79ryra+bSRGQ 501 b1slImA8YVJyuIDsj7kwzG7jnERNqnWxZ48AWkskmdHaVDP4BcelrTI3rMXdXF5D 502 rvs.example.com. ) 504 Example of a node with a HI, HIT, and two RVSs: 506 www.example.com. IN HIP ( 2 200100107B1A74DF365639CC39F1D578 507 AwEAAbdxyhNuSutc5EMzxTs9LBPCIkOFH8cIvM4p 508 9+LrV4e19WzK00+CI6zBCQTdtWsuxKbWIy87UOoJTwkUs7lBu+Upr1gsNrut79ryra+bSRGQ 509 b1slImA8YVJyuIDsj7kwzG7jnERNqnWxZ48AWkskmdHaVDP4BcelrTI3rMXdXF5D 510 rvs1.example.com. 511 rvs2.example.com. ) 513 8. Security Considerations 515 This section contains a description of the known threats involved 516 with the usage of the HIP DNS Extension. 518 In a manner similar to the IPSECKEY RR [RFC4025], the HIP DNS 519 Extension allows for the provision of two HIP nodes with the public 520 keying material (HI) of their peer. These HIs will be subsequently 521 used in a key exchange between the peers. Hence, the HIP DNS 522 Extension introduces the same kind of threats that IPSECKEY does, 523 plus threats caused by the possibility given to a HIP node to 524 initiate or accept a HIP exchange using "opportunistic" or 525 "unpublished Initiator HI" modes. 527 A HIP node SHOULD obtain HIP RRs from a trusted party trough a secure 528 channel ensuring data integrity and authenticity of the RRs. DNSSEC 529 [RFC4033] [RFC4034] [RFC4035] provides such a secure channel. 530 However, it should be emphasized that DNSSEC only offers data 531 integrity and authenticity guarantees to the channel between the DNS 532 server publishing a zone and the HIP node. DNSSEC does not ensure 533 that the entity publishing the zone is trusted. Therefore, the RRSIG 534 signature of the HIP RRSet MUST NOT be misinterpreted as a 535 certificate binding the HI and/or the HIT to the owner name. 537 In the absence of a proper secure channel, both parties are 538 vulnerable to MitM and DoS attacks, and unrelated parties might be 539 subject to DoS attacks as well. These threats are described in the 540 following sections. 542 8.1. Attacker Tampering with an Insecure HIP RR 544 The HIP RR contains public keying material in the form of the named 545 peer's public key (the HI) and its secure hash (the HIT). Both of 546 these are not sensitive to attacks where an adversary gains knowledge 547 of them. However, an attacker that is able to mount an active attack 548 on the DNS, i.e., tampers with this HIP RR (e.g., using DNS 549 spoofing), is able to mount Man-in-the-Middle attacks on the 550 cryptographic core of the eventual HIP exchange (Responder's HIP RR 551 rewritten by the attacker). 553 The HIP RR may contain a rendezvous server domain name resolved into 554 a destination IP address where the named peer is reachable by an I1, 555 as per the HIP Rendezvous Extension [I-D.ietf-hip-rfc5204-bis]. 556 Thus, an attacker able to tamper with this RR is able to redirect I1 557 packets sent to the named peer to a chosen IP address for DoS or MitM 558 attacks. Note that this kind of attack is not specific to HIP and 559 exists independently of whether or not HIP and the HIP RR are used. 560 Such an attacker might tamper with A and AAAA RRs as well. 562 An attacker might obviously use these two attacks in conjunction: It 563 will replace the Responder's HI and RVS IP address by its own in a 564 spoofed DNS packet sent to the Initiator HI, then redirect all 565 exchanged packets to him and mount a MitM on HIP. In this case, HIP 566 won't provide confidentiality nor Initiator HI protection from 567 eavesdroppers. 569 8.2. Hash and HITs Collisions 571 As with many cryptographic algorithms, some secure hashes (e.g., 572 SHA1, used by HIP to generate a HIT from an HI) eventually become 573 insecure, because an exploit has been found in which an attacker with 574 reasonable computation power breaks one of the security features of 575 the hash (e.g., its supposed collision resistance). This is why a 576 HIP end-node implementation SHOULD NOT authenticate its HIP peers 577 based solely on a HIT retrieved from the DNS, but SHOULD rather use 578 HI-based authentication. 580 8.3. DNSSEC 582 In the absence of DNSSEC, the HIP RR is subject to the threats 583 described in RFC 3833 [RFC3833]. 585 9. IANA Considerations 587 IANA has allocated one new RR type code (55) for the HIP RR from the 588 standard RR type space. 590 IANA does not need to open a new registry for public key algorithms 591 of the HIP RR because the HIP RR reuses "algorithms types" defined 592 for the IPSECKEY RR [RFC4025]. Presently defined values are shown 593 here for reference only: 595 0 is reserved 597 1 is DSA 599 2 is RSA 601 In the future, if a new algorithm is to be used for the HIP RR, a new 602 algorithm type and corresponding public key encoding should be 603 defined for the IPSECKEY RR. The HIP RR should reuse both the same 604 algorithm type and the same corresponding public key format as the 605 IPSECKEY RR. 607 10. Contributors 609 Pekka Nikander (pekka.nikander@nomadiclab.com) co-authored an 610 earlier, experimental version of this specification [RFC5205]. 612 11. Acknowledgments 614 As usual in the IETF, this document is the result of a collaboration 615 between many people. The authors would like to thank the author 616 (Michael Richardson), contributors, and reviewers of the IPSECKEY RR 617 [RFC4025] specification, after which this document was framed. The 618 authors would also like to thank the following people, who have 619 provided thoughtful and helpful discussions and/or suggestions, that 620 have helped improve this document: Jeff Ahrenholz, Rob Austein, Hannu 621 Flinck, Olafur Gudmundsson, Tom Henderson, Peter Koch, Olaf Kolkman, 622 Miika Komu, Andrew McGregor, Erik Nordmark, and Gabriel Montenegro. 623 Some parts of this document stem from the HIP specification 624 [I-D.ietf-hip-rfc5201-bis]. 626 12. References 628 12.1. Normative references 630 [I-D.ietf-hip-rfc5201-bis] 631 Moskowitz, R., Heer, T., Jokela, P., and T. Henderson, 632 "Host Identity Protocol Version 2 (HIPv2)", draft-ietf- 633 hip-rfc5201-bis-14 (work in progress), October 2013. 635 [I-D.ietf-hip-rfc5204-bis] 636 Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) 637 Rendezvous Extension", draft-ietf-hip-rfc5204-bis-02 (work 638 in progress), September 2012. 640 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 641 STD 13, RFC 1034, November 1987. 643 [RFC1035] Mockapetris, P., "Domain names - implementation and 644 specification", STD 13, RFC 1035, November 1987. 646 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 647 Requirement Levels", BCP 14, RFC 2119, March 1997. 649 [RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS 650 Specification", RFC 2181, July 1997. 652 [RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, 653 "DNS Extensions to Support IP Version 6", RFC 3596, 654 October 2003. 656 [RFC4025] Richardson, M., "A Method for Storing IPsec Keying 657 Material in DNS", RFC 4025, March 2005. 659 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 660 Rose, "DNS Security Introduction and Requirements", RFC 661 4033, March 2005. 663 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 664 Rose, "Resource Records for the DNS Security Extensions", 665 RFC 4034, March 2005. 667 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 668 Rose, "Protocol Modifications for the DNS Security 669 Extensions", RFC 4035, March 2005. 671 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 672 Encodings", RFC 4648, October 2006. 674 12.2. Informative references 676 [RFC2536] Eastlake, D., "DSA KEYs and SIGs in the Domain Name System 677 (DNS)", RFC 2536, March 1999. 679 [RFC3110] Eastlake, D., "RSA/SHA-1 SIGs and RSA KEYs in the Domain 680 Name System (DNS)", RFC 3110, May 2001. 682 [RFC3833] Atkins, D. and R. Austein, "Threat Analysis of the Domain 683 Name System (DNS)", RFC 3833, August 2004. 685 [RFC4423] Moskowitz, R. and P. Nikander, "Host Identity Protocol 686 (HIP) Architecture", RFC 4423, May 2006. 688 [RFC5205] Nikander, P. and J. Laganier, "Host Identity Protocol 689 (HIP) Domain Name System (DNS) Extensions", RFC 5205, 690 April 2008. 692 [RFC5206] Henderson, T., Ed., "End-Host Mobility and Multihoming 693 with the Host Identity Protocol", RFC 5206, April 2008. 695 Appendix A. Changes from RFC 5205 696 o Updated HIP references to revised HIP specifications. 698 Author's Address 700 Julien Laganier 701 Luminate Wireless, Inc. 702 Cupertino, CA 703 USA 705 EMail: julien.ietf@gmail.com