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Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust Copyright Line does not match the current year -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (April 13, 2007) is 6216 days in the past. Is this intentional? Checking references for intended status: Experimental ---------------------------------------------------------------------------- -- Looks like a reference, but probably isn't: '1' on line 468 == Outdated reference: A later version (-10) exists of draft-ietf-hip-base-07 -- Obsolete informational reference (is this intentional?): RFC 4423 (Obsoleted by RFC 9063) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 9 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group P. Nikander 3 Internet-Draft Ericsson Research Nomadic Lab 4 Intended status: Experimental J. Laganier 5 Expires: October 15, 2007 DoCoMo Euro-Labs 6 April 13, 2007 8 Host Identity Protocol (HIP) Domain Name System (DNS) Extensions 9 draft-ietf-hip-dns-09 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on October 15, 2007. 36 Copyright Notice 38 Copyright (C) The IETF Trust (2007). 40 Abstract 42 This document specifies a new resource record (RR) for the Domain 43 Name System (DNS), and how to use it with the Host Identity Protocol 44 (HIP). This RR allows a HIP node to store in the DNS its Host 45 Identity (HI, the public component of the node public-private key 46 pair), Host Identity Tag (HIT, a truncated hash of its public key), 47 and the Domain Names of its rendezvous servers (RVS). 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 52 2. Conventions used in this document . . . . . . . . . . . . . . 4 53 3. Usage Scenarios . . . . . . . . . . . . . . . . . . . . . . . 5 54 3.1. Simple static singly homed end-host . . . . . . . . . . . 6 55 3.2. Mobile end-host . . . . . . . . . . . . . . . . . . . . . 7 56 4. Overview of using the DNS with HIP . . . . . . . . . . . . . . 9 57 4.1. Storing HI, HIT and RVS in the DNS . . . . . . . . . . . . 9 58 4.2. Initiating connections based on DNS names . . . . . . . . 9 59 5. HIP RR Storage Format . . . . . . . . . . . . . . . . . . . . 10 60 5.1. HIT length format . . . . . . . . . . . . . . . . . . . . 10 61 5.2. PK algorithm format . . . . . . . . . . . . . . . . . . . 10 62 5.3. PK length format . . . . . . . . . . . . . . . . . . . . . 11 63 5.4. HIT format . . . . . . . . . . . . . . . . . . . . . . . . 11 64 5.5. Public key format . . . . . . . . . . . . . . . . . . . . 11 65 5.6. Rendezvous servers format . . . . . . . . . . . . . . . . 11 66 6. HIP RR Presentation Format . . . . . . . . . . . . . . . . . . 12 67 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 68 8. Security Considerations . . . . . . . . . . . . . . . . . . . 14 69 8.1. Attacker tampering with an insecure HIP RR . . . . . . . . 14 70 8.2. Hash and HITs Collisions . . . . . . . . . . . . . . . . . 15 71 8.3. DNSSEC . . . . . . . . . . . . . . . . . . . . . . . . . . 15 72 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 73 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 74 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 75 11.1. Normative references . . . . . . . . . . . . . . . . . . . 18 76 11.2. Informative references . . . . . . . . . . . . . . . . . . 19 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20 78 Intellectual Property and Copyright Statements . . . . . . . . . . 21 80 1. Introduction 82 This document specifies a new resource record (RR) for the Domain 83 Name System (DNS) [RFC1034], and how to use it with the Host Identity 84 Protocol (HIP) [I-D.ietf-hip-base]. This RR allows a HIP node to 85 store in the DNS its Host Identity (HI, the public component of the 86 node public-private key pair), Host Identity Tag (HIT, a truncated 87 hash of its HI), and the Domain Names of its rendezvous servers (RVS) 88 [I-D.ietf-hip-rvs]. 90 Currently, most of the Internet applications that need to communicate 91 with a remote host first translate a domain name (often obtained via 92 user input) into one or more IP address(es). This step occurs prior 93 to communication with the remote host, and relies on a DNS lookup. 95 With HIP, IP addresses are intended to be used mostly for on-the-wire 96 communication between end hosts, while most Upper Layer Protocols 97 (ULP) and applications use HIs or HITs instead (ICMP might be an 98 example of an ULP not using them). Consequently, we need a means to 99 translate a domain name into an HI. Using the DNS for this 100 translation is pretty straightforward: We define a new HIP resource 101 record. Upon query by an application or ULP for a name to IP address 102 lookup, the resolver would then additionally perform a name to HI 103 lookup, and use it to construct the resulting HI to IP address 104 mapping (which is internal to the HIP layer). The HIP layer uses the 105 HI to IP address mapping to translate HIs and HITs into IP addresses 106 and vice versa. 108 The HIP rendezvous extensions [I-D.ietf-hip-rvs] proposal allows a 109 HIP node to be reached via the IP address(es) of a third party, the 110 node's rendezvous server (RVS). An initiator willing to establish a 111 HIP association with a responder served by a RVS would typically 112 initiate a HIP exchange by sending an I1 towards the RVS IP address 113 rather than towards the responder IP address. Consequently, we need 114 a means to to find the name of a rendezvous server for a given host 115 name. 117 This document introduces the new HIP DNS Resource Record to store 118 Rendezvous Server (RVS), Host Identity (HI) and Host Identity Tag 119 (HIT) information. 121 2. Conventions used in this document 123 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 124 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 125 document are to be interpreted as described in RFC2119 [RFC2119]. 127 3. Usage Scenarios 129 In this section, we briefly introduce a number of usage scenarios 130 where the DNS is useful with the Host Identity Protocol. 132 With HIP, most application and ULPs are unaware of the IP addresses 133 used to carry packets on the wire. Consequently, a HIP node could 134 take advantage of having multiple IP addresses for fail-over, 135 redundancy, mobility, or renumbering, in a manner which is 136 transparent to most ULPs and applications (because they are bound to 137 HIs, hence they are agnostic to these IP address changes). 139 In these situations, for a node to be reachable by reference to its 140 Fully Qualified Domain Name (FQDN), the following information should 141 be stored in the DNS: 143 o A set of IP address(es) through A [RFC1035] and AAAA [RFC3596] RR 144 sets (RRSets [RFC2181]). 146 o A Host Identity (HI), Host Identity Tag (HIT) and possibly a set 147 of rendezvous servers (RVS) through HIP RRs. 149 When a HIP node wants to initiate a communication with another HIP 150 node, it first needs to perform a HIP base exchange to set up a HIP 151 association towards its peer. Although such an exchange can be 152 initiated opportunistically, i.e., without prior knowledge of the 153 responder's HI, by doing so both nodes knowingly risk man-in-the- 154 middle attacks on the HIP exchange. To prevent these attacks, it is 155 recommended that the initiator first obtain the HI of the responder, 156 and then initiate the exchange. This can be done, for example, 157 through manual configuration or DNS lookups. Hence, a new HIP RR is 158 introduced. 160 When a HIP node is frequently changing its IP address(es), the 161 natural DNS latency for propagating changes may prevent it from 162 publishing its new IP address(es) in the DNS. For solving this 163 problem, the HIP architecture [RFC4423] introduces rendezvous servers 164 (RVS). A HIP host uses a rendezvous server as a rendezvous point, to 165 maintain reachability with possible HIP initiators while moving 166 [I-D.ietf-hip-mm]. Such a HIP node would publish in the DNS its RVS 167 domain name(s) in a HIP RR, while keeping its RVS up-to-date with its 168 current set of IP addresses. 170 When a HIP node wants to initiate a HIP exchange with a responder it 171 will perform a number of DNS lookups. Depending on the type of the 172 implementation, the order in which those lookups will be issued may 173 vary. For instance, implementations using HIT in APIs may typically 174 first query for HIP resource records at the responder FQDN, while 175 those using IP address in APIs may typically first query for A and/or 176 AAAA resource records. 178 In the following we assume that the initiator first queries for HIP 179 resource records at the responder FQDN. 181 If the query for the HIP type was responded to with a DNS answer with 182 RCODE=3 (Name Error), then the responder's information is not present 183 in the DNS and further queries for the same owner name SHOULD NOT be 184 made. 186 In case the query for the HIP records returned a DNS answer with 187 RCODE=0 (No Error) and an empty answer section, it means that no HIP 188 information is avalaible at the responder name. In such a case, if 189 the initiator has been configured with a policy to fallback to 190 opportunistic HIP (initiating without knowing the responder's HI) or 191 plain IP, it would sends out more queries for A and AAAA types at the 192 responder's FQDN. 194 Depending on the combinations of answers the situations described in 195 Section 3.1 and Section 3.2 can occur. 197 Note that storing HIP RR information in the DNS at a FQDN which is 198 assigned to a non-HIP node might have ill effects on its reachability 199 by HIP nodes. 201 3.1. Simple static singly homed end-host 203 A HIP node (R) with a single static network attachment, wishing to be 204 reachable by reference to its FQDN (www.example.com), would store in 205 the DNS, in addition to its IP address(es) (IP-R), its Host Identity 206 (HI-R) and Host Identity Tag (HIT-R) in a HIP resource record. 208 An initiator willing to associate with a node would typically issue 209 the following queries: 211 o QNAME=www.example.com, QTYPE=HIP 213 o (QCLASS=IN is assumed and omitted from the examples) 215 Which returns a DNS packet with RCODE=0 and one or more HIP RRs with 216 the HIT and HI (e.g. HIT-R and HI-R) of the responder in the answer 217 section, but no RVS. 219 o QNAME=www.example.com, QTYPE=A QNAME=www.example.com, QTYPE=AAAA 221 Which returns DNS packets with RCODE=0 and one or more A or AAAA RRs 222 containing IP address(es) of the responder (e.g. IP-R) in the answer 223 section. 225 Caption: In the remainder of this document, for the sake of keeping 226 diagrams simple and concise, several DNS queries and answers 227 are represented as one single transaction, while in fact 228 there are several queries and answers flowing back and 229 forth, as described in the textual examples. 231 [HIP? A? ] 232 [www.example.com] +-----+ 233 +-------------------------------->| | 234 | | DNS | 235 | +-------------------------------| | 236 | | [HIP? A? ] +-----+ 237 | | [www.example.com] 238 | | [HIP HIT-R HI-R ] 239 | | [A IP-R ] 240 | v 241 +-----+ +-----+ 242 | |--------------I1------------->| | 243 | I |<-------------R1--------------| R | 244 | |--------------I2------------->| | 245 | |<-------------R2--------------| | 246 +-----+ +-----+ 248 Static Singly Homed Host 250 The initiator would then send an I1 to the responder's IP addresses 251 (IP-R). 253 3.2. Mobile end-host 255 A mobile HIP node (R) wishing to be reachable by reference to its 256 FQDN (www.example.com) would store in the DNS, possibly in addition 257 to its IP address(es) (IP-R), its HI (HI-R), HIT (HIT-R) and the 258 domain name(s) of its rendezvous server(s) (e.g. rvs.example.com) in 259 HIP resource record(s). The mobile HIP node also needs to notify its 260 rendezvous servers of any change in its set of IP address(es). 262 An initiator willing to associate with such mobile node would 263 typically issue the following queries: 265 o QNAME=www.example.com, QTYPE=HIP 267 Which returns a DNS packet with RCODE=0 and one or more HIP RRs with 268 the HIT, HI and RVS domain name(s) (e.g. HIT-R, HI-R, and 269 rvs.example.com) of the responder in the answer section. 271 o QNAME=rvs.example.com, QTYPE=A QNAME=www.example.com, QTYPE=AAAA 273 Which returns DNS packets with RCODE=0 and one or more A or AAAA RRs 274 containing IP address(es) of the responder's RVS (e.g. IP-RVS) in 275 the answer section. 277 [HIP? ] 278 [www.example.com] 280 [A? ] 281 [rvs.example.com] +-----+ 282 +----------------------------------------->| | 283 | | DNS | 284 | +----------------------------------------| | 285 | | [HIP? ] +-----+ 286 | | [www.example.com ] 287 | | [HIP HIT-R HI-R rvs.example.com] 288 | | 289 | | [A? ] 290 | | [rvs.example.com] 291 | | [A IP-RVS ] 292 | | 293 | | +-----+ 294 | | +------I1----->| RVS |-----I1------+ 295 | | | +-----+ | 296 | | | | 297 | | | | 298 | v | v 299 +-----+ +-----+ 300 | |<---------------R1------------| | 301 | I |----------------I2----------->| R | 302 | |<---------------R2------------| | 303 +-----+ +-----+ 305 Mobile End-Host 307 The initiator would then send an I1 to the RVS IP address (IP-RVS). 308 Following, the RVS will relay the I1 up to the mobile node's IP 309 address (IP-R), which will complete the HIP exchange. 311 4. Overview of using the DNS with HIP 313 4.1. Storing HI, HIT and RVS in the DNS 315 For any HIP node its Host Identity (HI), the associated Host Identity 316 Tag (HIT), and the FQDN of its possible RVSs can be stored in a DNS 317 HIP RR. Any conforming implementation may store a Host Identity (HI) 318 and its associated Host Identity Tag (HIT) in a DNS HIP RDATA format. 319 HI and HIT are defined in Section 3 of [I-D.ietf-hip-base]. 321 Upon return of a HIP RR, a host MUST always calculate the HI- 322 derivative HIT to be used in the HIP exchange, as specified in 323 Section 3 of the HIP base specification [I-D.ietf-hip-base], while 324 the HIT possibly embedded along SHOULD only be used as an 325 optimization (e.g. table lookup). 327 The HIP resource record may also contain one or more domain name(s) 328 of rendezvous server(s) towards which HIP I1 packets might be sent to 329 trigger the establishment of an association with the entity named by 330 this resource record [I-D.ietf-hip-rvs]. 332 The rendezvous server field of the HIP resource record stored at a 333 given owner name MAY include the owner name itself. A semantically 334 equivalent situation occurs if no rendezvous server is present in the 335 HIP resource record stored at that owner name. Such situations 336 occurs in two cases: 338 o The host is mobile, and the A and/or AAAA resource record(s) 339 stored at its host name contains the IP address(es) of its 340 rendezvous server rather than its own one. 342 o The host is stationary, and can be reached directly at IP 343 address(es) contained in A and/or AAAA resource record(s) stored 344 at its host name. This a degenerated case of rendezvous service 345 where the host somewhat acts as a rendezvous server for itself. 347 An RVS receiving such an I1 would then relay it to the appropriate 348 responder (the owner of the I1 receiver HIT). The responder will 349 then complete the exchange with the initiator, typically without 350 ongoing help from the RVS. 352 4.2. Initiating connections based on DNS names 354 On a HIP node, a Host Identity Protocol exchange SHOULD be initiated 355 whenever an ULP attempts to communicate with an entity and the DNS 356 lookup returns HIP resource records. 358 5. HIP RR Storage Format 360 The RDATA for a HIP RR consists of a public key algorithm type, the 361 HIT length, a HIT, a public key, and optionally one or more 362 rendezvous server(s). 364 0 1 2 3 365 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 1 366 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 367 | HIT length | PK algorithm | PK length | 368 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 369 | | 370 ~ HIT ~ 371 | | 372 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 373 | | | 374 +-+-+-+-+-+-+-+-+-+-+-+ + 375 | Public Key | 376 ~ ~ 377 | | 378 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 379 | | | 380 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + 381 | | 382 ~ Rendezvous Servers ~ 383 | | 384 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 385 | | 386 +-+-+-+-+-+-+-+ 388 The HIT length, PK algorithm, PK length, HIT and Public Key field are 389 REQUIRED. The Rendezvous Servers field is OPTIONAL. 391 5.1. HIT length format 393 The HIT length indicates the length in bytes of the HIT field. This 394 is an 8 bits unsigned integer. 396 5.2. PK algorithm format 398 The PK algorithm field indicates the public key cryptographic 399 algorithm and the implied public key field format. This is an 8 bits 400 unsigned integer. This document reuses the values defined for the 401 'algorithm type' of the IPSECKEY RR [RFC4025]. 403 Presently defined values are listed in Section 9 for reference. 405 5.3. PK length format 407 The PK length indicates the length in bytes of the Public key field. 408 This is a 16 bits unsigned integer in network byte order. 410 5.4. HIT format 412 The HIT is stored, as a binary value, in network byte order. 414 5.5. Public key format 416 Both of the public key types defined in this document (RSA and DSA) 417 reuse the public key formats defined for the IPSECKEY RR [RFC4025]. 419 The DSA key format is defined in RFC2536 [RFC2536]. 421 The RSA key format is defined in RFC3110 [RFC3110] and the RSA key 422 size limit (4096 bits) is relaxed in the IPSECKEY RR [RFC4025] 423 specification. 425 5.6. Rendezvous servers format 427 The Rendezvous servers field indicates one or more variable length 428 wire-encoded domain names of rendezvous server(s), as described in 429 Section 3.3 of RFC1035 [RFC1035]. The wire-encoded format is self- 430 describing, so the length is implicit. The domain names MUST NOT be 431 compressed. The rendezvous server(s) are listed in order of 432 preference (i.e. first rendezvous server(s) are preferred), defining 433 an implicit order amongst rendezvous server of a single RR. When 434 multiple HIP RRs are present at the same owner name, this implicit 435 order of rendezvous servers within an RR MUST NOT be used to infer a 436 preference order between rendezvous servers stored in different RRs. 438 6. HIP RR Presentation Format 440 This section specifies the representation of the HIP RR in a zone 441 master file. 443 The HIT length field is not represented as it is implicitly known 444 thanks to the HIT field representation. 446 The PK algorithm field is represented as unsigned integers. 448 The HIT field is represented as the Base16 encoding [RFC4648] (a.k.a. 449 hex or hexadecimal) of the HIT. The encoding MUST NOT contain 450 whitespaces to be able to distinguish it from the public key field. 452 The Public Key field is represented as the Base64 encoding [RFC4648] 453 of the public key. The encoding MUST NOT contain whitespace(s) to be 454 able to distinguish from the Rendezvous Servers field. 456 The PK length field is not represented as it is implicitly known 457 thanks to the Public key field representation containing no 458 whitespaces. 460 The Rendezvous Servers field is represented by one or more domain 461 name(s) separated by whitespace(s). 463 The complete representation of the HPIHI record is: 465 IN HIP ( pk-algorithm 466 base16-encoded-hit 467 base64-encoded-public-key 468 rendezvous-server[1] 469 ... 470 rendezvous-server[n] ) 472 When no RVS are present, the representation of the HPIHI record is: 474 IN HIP ( pk-algorithm 475 base16-encoded-hit 476 base64-encoded-public-key ) 478 7. Examples 480 In the examples below, the public key field containing no whitespace 481 is wrapped since it does not fit in a single line of this document. 483 Example of a node with HI and HIT but no RVS: 485 www.example.com. IN HIP ( 2 200100107B1A74DF365639CC39F1D578 486 AwEAAbdxyhNuSutc5EMzxTs9LBPCIkOFH8cIvM4p 487 9+LrV4e19WzK00+CI6zBCQTdtWsuxKbWIy87UOoJTwkUs7lBu+Upr1gsNrut79ryra+bSRGQ 488 b1slImA8YVJyuIDsj7kwzG7jnERNqnWxZ48AWkskmdHaVDP4BcelrTI3rMXdXF5D ) 490 Example of a node with a HI, HIT and one RVS: 492 www.example.com. IN HIP ( 2 200100107B1A74DF365639CC39F1D578 493 AwEAAbdxyhNuSutc5EMzxTs9LBPCIkOFH8cIvM4p 494 9+LrV4e19WzK00+CI6zBCQTdtWsuxKbWIy87UOoJTwkUs7lBu+Upr1gsNrut79ryra+bSRGQ 495 b1slImA8YVJyuIDsj7kwzG7jnERNqnWxZ48AWkskmdHaVDP4BcelrTI3rMXdXF5D 496 rvs.example.com. ) 498 Example of a node with a HI, HIT and two RVS: 500 www.example.com. IN HIP ( 2 200100107B1A74DF365639CC39F1D578 501 AwEAAbdxyhNuSutc5EMzxTs9LBPCIkOFH8cIvM4p 502 9+LrV4e19WzK00+CI6zBCQTdtWsuxKbWIy87UOoJTwkUs7lBu+Upr1gsNrut79ryra+bSRGQ 503 b1slImA8YVJyuIDsj7kwzG7jnERNqnWxZ48AWkskmdHaVDP4BcelrTI3rMXdXF5D 504 rvs1.example.com. 505 rvs2.example.com. ) 507 8. Security Considerations 509 This section contains a description of the known threats involved 510 with the usage of the HIP DNS extensions. 512 In a manner similar to the IPSECKEY RR [RFC4025], the HIP DNS 513 Extensions allows to provision two HIP nodes with the public keying 514 material (HI) of their peer. These HIs will be subsequently used in 515 a key exchange between the peers. Hence, the HIP DNS Extensions 516 introduce the same kind of threats that IPSECKEY does, plus threats 517 caused by the possibility given to a HIP node to initiate or accept a 518 HIP exchange using "opportunistic" or "unpublished initiator HI" 519 modes. 521 A HIP node SHOULD obtain HIP RRs from a trusted party trough a secure 522 channel insuring data integrity and authenticity of the RRs. DNSSEC 523 [RFC4033] [RFC4034] [RFC4035] provides such a secure channel. 524 However, it should be emphasized that DNSSEC does only offer data 525 integrity and authenticty guarantees to the channel between the DNS 526 server publishing a zone and the HIP node. DNSSEC does not ensure 527 that the entity publishing the zone is trusted. Therefore, the RRSIG 528 signature of the HIP RRSet MUST NOT be misinterpreted as a 529 certificate binding the HI and/or the HIT to the owner name. 531 In the absence of a proper secure channel, both parties are 532 vulnerable to MitM and DoS attacks, and unrelated parties might be 533 subject to DoS attacks as well. These threats are described in the 534 following sections. 536 8.1. Attacker tampering with an insecure HIP RR 538 The HIP RR contains public keying material in the form of the named 539 peer's public key (the HI) and its secure hash (the HIT). Both of 540 these are not sensitive to attacks where an adversary gains knowledge 541 of them. However, an attacker that is able to mount an active attack 542 on the DNS, i.e., tampers with this HIP RR (e.g. using DNS spoofing) 543 is able to mount Man-in-the-Middle attacks on the cryptographic core 544 of the eventual HIP exchange (responder's HIP RR rewritten by the 545 attacker). 547 The HIP RR may contain a rendezvous server domain name resolved into 548 a destination IP address where the named peer is reachable by an I1 549 (HIP Rendezvous Extensions IPSECKEY RR [I-D.ietf-hip-rvs]). Thus, an 550 attacker able to tamper with this RR is able to redirect I1 packets 551 sent to the named peer to a chosen IP address, for DoS or MitM 552 attacks. Note that this kind of attack is not specific to HIP and 553 exists independently of whether or not HIP and the HIP RR are used. 554 Such an attacker might tamper with A and AAAA RRs as well. 556 An attacker might obviously use these two attacks in conjunction: It 557 will replace the responder's HI and RVS IP address by its own in a 558 spoofed DNS packet sent to the initiator HI, then redirect all 559 exchanged packets to him and mount a MitM on HIP. In this case HIP 560 won't provide confidentiality nor initiator HI protection from 561 eavesdroppers. 563 8.2. Hash and HITs Collisions 565 As many cryptographic algorithms, some secure hashes (e.g. SHA1, 566 used by HIP to generate a HIT from an HI) eventually become insecure, 567 because an exploit has been found in which an attacker with a 568 reasonable computation power breaks one of the security features of 569 the hash (e.g. its supposed collision resistance). This is why a HIP 570 end-node implementation SHOULD NOT authenticate its HIP peers based 571 solely on a HIT retrieved from the DNS, but SHOULD rather use HI- 572 based authentication. 574 8.3. DNSSEC 576 In the absence of DNSSEC, the HIP RR is subject to the threats 577 described in RFC 3833 [RFC3833]. 579 9. IANA Considerations 581 IANA should allocate one new RR type code (TBD, 55?) for the HIP RR 582 from the standard RR type space. 584 IANA does not need to open a new registry for public key algorithms 585 of the HIP RR because the HIP RR reuses "algorithms types" defined 586 for the IPSECKEY RR [RFC4025]. Presently defined values are shown 587 here for reference only: 589 0 is reserved 591 1 is RSA 593 2 is DSA 595 In the future, if a new algorithm is to be used for the HIP RR, a new 596 algorithm type and corresponding public key encoding should be 597 defined for the IPSECKEY RR. The HIP RR should reuse both the same 598 algorithm type and the same corresponding public key format as the 599 IPSECKEY RR. 601 10. Acknowledgments 603 As usual in the IETF, this document is the result of a collaboration 604 between many people. The authors would like to thanks the author 605 (Michael Richardson), contributors and reviewers of the IPSECKEY RR 606 [RFC4025] specification, which this document was framed after. The 607 authors would also like to thanks the following people, who have 608 provided thoughtful and helpful discussions and/or suggestions, that 609 have helped improving this document: Jeff Ahrenholz, Rob Austein, 610 Hannu Flinck, Olafur Gu[eth]mundsson, Tom Henderson, Peter Koch, Olaf 611 Kolkman, Miika Komu, Andrew McGregor, Erik Nordmark, and Gabriel 612 Montenegro. Some parts of this document stem from 613 [I-D.ietf-hip-base]. 615 Julien Laganier is partly funded by Ambient Networks, a research 616 project supported by the European Commission under its Sixth 617 Framework Program. The views and conclusions contained herein are 618 those of the authors and should not be interpreted as necessarily 619 representing the official policies or endorsements, either expressed 620 or implied, of the Ambient Networks project or the European 621 Commission. 623 11. References 625 11.1. Normative references 627 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 628 STD 13, RFC 1034, November 1987. 630 [RFC1035] Mockapetris, P., "Domain names - implementation and 631 specification", STD 13, RFC 1035, November 1987. 633 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 634 Requirement Levels", BCP 14, RFC 2119, March 1997. 636 [RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS 637 Specification", RFC 2181, July 1997. 639 [RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, 640 "DNS Extensions to Support IP Version 6", RFC 3596, 641 October 2003. 643 [RFC4025] Richardson, M., "A Method for Storing IPsec Keying 644 Material in DNS", RFC 4025, March 2005. 646 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 647 Rose, "DNS Security Introduction and Requirements", 648 RFC 4033, March 2005. 650 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 651 Rose, "Resource Records for the DNS Security Extensions", 652 RFC 4034, March 2005. 654 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 655 Rose, "Protocol Modifications for the DNS Security 656 Extensions", RFC 4035, March 2005. 658 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 659 Encodings", RFC 4648, October 2006. 661 [I-D.ietf-hip-base] 662 Moskowitz, R., "Host Identity Protocol", 663 draft-ietf-hip-base-07 (work in progress), February 2007. 665 [I-D.ietf-hip-rvs] 666 Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) 667 Rendezvous Extension", draft-ietf-hip-rvs-05 (work in 668 progress), June 2006. 670 11.2. Informative references 672 [RFC2536] Eastlake, D., "DSA KEYs and SIGs in the Domain Name System 673 (DNS)", RFC 2536, March 1999. 675 [RFC3110] Eastlake, D., "RSA/SHA-1 SIGs and RSA KEYs in the Domain 676 Name System (DNS)", RFC 3110, May 2001. 678 [RFC4423] Moskowitz, R. and P. Nikander, "Host Identity Protocol 679 (HIP) Architecture", RFC 4423, May 2006. 681 [I-D.ietf-hip-mm] 682 Henderson, T., "End-Host Mobility and Multihoming with the 683 Host Identity Protocol", draft-ietf-hip-mm-05 (work in 684 progress), March 2007. 686 [RFC3833] Atkins, D. and R. Austein, "Threat Analysis of the Domain 687 Name System (DNS)", RFC 3833, August 2004. 689 Authors' Addresses 691 Pekka Nikander 692 Ericsson Research Nomadic Lab 693 JORVAS FIN-02420 694 FINLAND 696 Phone: +358 9 299 1 697 Email: pekka.nikander@nomadiclab.com 699 Julien Laganier 700 DoCoMo Communications Laboratories Europe GmbH 701 Landsberger Strasse 312 702 Munich 80687 703 Germany 705 Phone: +49 89 56824 231 706 Email: julien.ietf@laposte.net 707 URI: http://www.docomolab-euro.com/ 709 Full Copyright Statement 711 Copyright (C) The IETF Trust (2007). 713 This document is subject to the rights, licenses and restrictions 714 contained in BCP 78, and except as set forth therein, the authors 715 retain all their rights. 717 This document and the information contained herein are provided on an 718 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 719 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 720 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 721 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 722 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 723 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 725 Intellectual Property 727 The IETF takes no position regarding the validity or scope of any 728 Intellectual Property Rights or other rights that might be claimed to 729 pertain to the implementation or use of the technology described in 730 this document or the extent to which any license under such rights 731 might or might not be available; nor does it represent that it has 732 made any independent effort to identify any such rights. 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