idnits 2.17.1 draft-ietf-dnsop-delegation-trust-maintainance-01.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Line 512 has weird spacing: '... full i.e. ...' == Line 515 has weird spacing: '...augment i.e. ...' -- The document date (January 4, 2014) is 3757 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-06) exists of draft-ietf-dnsop-dnssec-key-timing-03 Summary: 0 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 dnsop W. Kumari 3 Internet-Draft Google 4 Intended status: Informational O. Gudmundsson 5 Expires: July 8, 2014 Shinkuro Inc. 6 G. Barwood 8 January 4, 2014 10 Automating DNSSEC delegation trust maintenance 11 draft-ietf-dnsop-delegation-trust-maintainance-01 13 Abstract 15 This document describes a method to allow DNS operators to more 16 easily update DNSSEC Key Signing Keys using DNS as communication 17 channel. This document does not address the initial configuration of 18 trust anchors for a domain. The technique described is aimed at 19 delegations in which it is currently hard to move information from 20 the child to parent. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on July 8, 2014. 39 Copyright Notice 41 Copyright (c) 2014 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 58 1.2. Requirements notation . . . . . . . . . . . . . . . . . . 4 59 2. Background . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 2.1. DNS delegations . . . . . . . . . . . . . . . . . . . . . 4 61 2.2. Relationship between Parent and Child DNS operator . . . 5 62 2.2.1. Solution Space . . . . . . . . . . . . . . . . . . . 6 63 2.2.2. DNSSEC key change process . . . . . . . . . . . . . . 7 64 3. CDS / CDNSKEY (Child DS/ Child DNSKEY) record definitions . . 7 65 3.1. CDS Resource Record Format . . . . . . . . . . . . . . . 7 66 3.2. CDNSKEY Resource Record Format . . . . . . . . . . . . . 8 67 4. Automating DS maintainance with CDS/CDNSKEY records . . . . . 8 68 4.1. CDS / CDNSKEY processing rules . . . . . . . . . . . . . 8 69 5. Child's CDS / CDNSKEY Publication . . . . . . . . . . . . . . 9 70 6. Parent side CDS / CDNSKEY Consumption . . . . . . . . . . . . 9 71 6.1. Detecting a changed CDS / CDNSKEY . . . . . . . . . . . . 9 72 6.1.1. CDS / CDNSKEY Polling . . . . . . . . . . . . . . . . 10 73 6.1.2. Other mechanisms . . . . . . . . . . . . . . . . . . 10 74 6.2. Using the new CDS / CDNSKEY records . . . . . . . . . . . 10 75 6.2.1. Parent calculates DS . . . . . . . . . . . . . . . . 11 76 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 77 8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 12 78 9. Security Considerations . . . . . . . . . . . . . . . . . . . 12 79 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 80 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 81 11.1. Normative References . . . . . . . . . . . . . . . . . . 14 82 11.2. Informative References . . . . . . . . . . . . . . . . . 14 83 Appendix A. RRR background . . . . . . . . . . . . . . . . . . . 15 84 Appendix B. Changes / Author Notes. . . . . . . . . . . . . . . 15 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 87 1. Introduction 89 When a DNS operator first signs their zone, they need to communicate 90 their DS record(s) (or DNSKEY(s)) to their parent through some out- 91 of-band method to complete the chain of trust. 93 Each time the child changes/rolls the key that is represented in the 94 parent, the new and/or deleted key information has to be communicated 95 to the parent and published there. How this information is sent to 96 the parent depends on the relationship the child has with the parent. 98 In many cases this is a manual process, and not an easy one. For 99 each key roll, there may be two interactions with the parent. Any 100 manual process is susceptible to mistakes and/or errors. In 101 addition, due to the annoyance factor of the process, operators may 102 avoid performing key rollovers or skip needed steps to publish the 103 new DS at the parent. 105 DNSSEC provides data integrity to information published in DNS; thus 106 DNS publication can be used to automate maintenance of delegation 107 information. This document describes a method to automate 108 publication of subsequent DS records, after the initial one has been 109 published. 111 Readers are expected to be familiar with DNSSEC, including [RFC4033], 112 [RFC4034], [RFC4035], [RFC5011] and [RFC6781]. 114 This document is a compilation of two earlier drafts: draft-barwood- 115 dnsop-ds-publish[I-D.ds-publish] and draft-wkumari-dnsop-ezkeyroll 117 This document outlines a technique in which the parent periodically 118 (or upon request) polls its signed children and automatically publish 119 new DS records. To a large extent, the procedures this document 120 follows are as described in [RFC6781] section 4.1.2 122 This technique is in some ways similar to RFC 5011 style rollovers, 123 but for sub-domains DS records, instead of trust anchors 125 This technique is designed to be friendly both to fully automated 126 tools and humans. Fully automated tools can perform all the actions 127 needed without human intervention, and thus can monitor when it is 128 safe to move to the next step. 130 CDS only allows transferring information about DNSSEC keys (DS and 131 DNSKEY) from the child to the parental agent. It lists exactly what 132 the parent should publish, and allows for publication of stand-by 133 keys. A different protocol, [I-D.csync], can be used to maintain 134 other important delegation information, such as NS and glue. These 135 two protocols have been kept as separate solutions because the 136 problems are fundamentally different, and a combined solution is 137 overly complex. 139 This document describes a method for automating maintanance of the 140 delegation trust information, and proposes a polled / periodic 141 trigger for simplicity. Some users may prefer a different trigger, 142 such as a button on a webpage, a REST interface, DNS NOTIFY, etc. 143 These alternate / additional triggers are not discussed in this 144 document. 146 1.1. Terminology 148 There terminology we use is defined in this section 150 Highlighted roles 152 o Child: "The entity on record that has the delegation of the domain 153 from the parent" 155 o Parent: "The domain in which the child is registered" 157 o Child DNS operator: "The entity that maintains and publishes the 158 zone information for the child DNS" 160 o Parent DNS operator: "The entity that maintains and publishes the 161 zone information for the parent DNS" 163 o Parental Agent: "The entity that the child has relationship with, 164 to change its delegation information." 166 o Provisioning system: "A system that the operator of the master DNS 167 server operates to maintain the information published in the DNS. 168 This includes the systems that sign the DNS data." 170 RRR is our shorthand for Registry/Registrar/Registrant model of 171 parent child relationship see Appendix A for more. 173 1.2. Requirements notation 175 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 176 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 177 document are to be interpreted as described in [RFC2119]. 179 2. Background 181 2.1. DNS delegations 183 DNS operation consists of delegations of authority. For each 184 delegation there are (most of the time) two parties, the parent and 185 the child. 187 The parent publishes information about the delegations to the child; 188 for the name-servers it publishes an NS RRset that lists a hint for 189 name-servers that are authoritative for the child. The child also 190 publishes a NS RRset, and this set is the authoritative list of name- 191 servers to the child zone. 193 The second RRset the parent sometimes publishes is the DS set. The 194 DS RRset provides information about the key(s) that the child has 195 told the parent it will use to sign its DNSKEY RRset. In DNSSEC 196 trust relationship between zones is provided by the following chain: 198 parent DNSKEY --> DS --> child DNSKEY. 200 A prior proposal [I-D.auto-cpsync] suggested that the child send an 201 "update" to the parent via a mechanism similar to Dynamic Update. 202 The main issue became: How does the child find the actual parental 203 agent/server to send the update to? While that could have been 204 solved via technical means, the proposal died. 206 As the DS record can only be present at the parent RFC4034 [RFC4034], 207 some other record/method is needed to automate the expression of what 208 the parental zone DS records contents ought to be. One possibility 209 is to use flags in the DNSKEY record. If the SEP bit is set, this 210 indicates that the DNSKEY is intended for use as a secure entry 211 point. This DNSKEY signs the DNSKEY RRset, and the Parental Agent 212 can calculate DS records based on that. But this fails to meet some 213 operating needs, including the child having no influence what DS 214 digest algorithms are used and DS records can only be published for 215 keys that are in the DNSKEY RRset. 217 2.2. Relationship between Parent and Child DNS operator 219 In the real world, there are many different relationships between the 220 parent and child DNS operators. The type of relationship affects how 221 the child operator communicates with the parent. This section will 222 highlight some of the different situations, but is by no means a 223 complete list. 225 Different communication paths: 227 o Direct/API: The child can change the delegation information via 228 automated/scripted means EPP[RFC5730] used by many TLDs is an 229 example of this. Another example is the web service's 230 programmatic interfaces that Registrars make available to their 231 Reseller's. 233 o User Interface: The Child uses a (web) site set up by the Parental 234 Agent for updating delegation information. 236 o Indirect: The communication has to be transmitted via out-of-band 237 between two parties, such as email, telephone etc.. This is common 238 when the Child's DNS operator is neither the child itself nor the 239 Registrar for the domain but a third party. 241 o Multi-step Combinations: The information flows through an 242 intermediary. It is possible, but unlikely, that all the steps 243 are automated via API's and there are no humans are involved. 245 A domain name holder (Child) may operate its own DNS servers or 246 outsource the operation. While we use the word parent as a singular, 247 parent can consist of single entity or a composite of many discrete 248 parts that have rules and roles. We refer to the entity that the 249 child corresponds with as the Parent. 251 Another common case is the enterprise case in which an organization 252 may delegate parts of its name-space to be operated by a group that 253 is not the same as that which operates the enterprise's DNS servers. 254 In this case the flow of information is frequently handled in either 255 an ad hoc manner or via some corporate mechanism; this can range from 256 email to fully-automated operation. The word enterprise above covers 257 all organizations where the domains are not sold on the open market 258 and there is some relationship between the entities. 260 2.2.1. Solution Space 262 This document is aimed at the cases in which there is an 263 organizational separation of the child and parent. 265 A further complication is when the Child DNS Operation is not the 266 Child. There are two common cases of this, 268 a) The Parental Agent (e.g. registrar) handles the DNS operation 270 b) A third party takes care of the DNS operation. 272 If the Parental Agent is the DNS operator, life is much easier, as 273 the Parental Agent can inject any delegation changes directly into 274 the Parents Provisioning system. The techniques described below are 275 not needed in the case when Parental Agent is the DNS operator. 277 In the case of a third party DNS operator, the Child either needs to 278 relay changes in DNS delegation or give the Child Operator access to 279 its delegation/registration account. 281 Some parents want the child to express the changes in trust anchors 282 via DS records, while others want to receive DNSKEY records and 283 calculate the DS records themselves. There is no consensus on which 284 method is better; both have good reasons to exist. The proposal 285 below can operate with both models, but the child needs to be aware 286 of the parental policies. 288 2.2.2. DNSSEC key change process 290 After a Child DNS operator first signs the zone, there is a need to 291 interact with the Parent, for example via the delegation account 292 interface, to "upload / paste-in the zone's DS information". The 293 action of logging in through the delegation account user interface 294 authenticates that the user is authorized to change delegation 295 information published in the parent zone. In the case where the 296 "Child DNS Operator" does not have access to the registration 297 account, the Child needs to perform the action. 299 At a later date, the Child Operator may want to publish a new DS 300 record in the parent, either because they are rolling keys, or 301 because they want to publish a stand-by key. This involves 302 performing the same process as before. Furthermore when this is a 303 manual process with cut and paste; operational mistakes will happen. 304 Or worse the update action in not performed at all. 306 3. CDS / CDNSKEY (Child DS/ Child DNSKEY) record definitions 308 This document specifies two new DNS RRtypes (CDS and CDNSKEY) that 309 indicates what the Child wants to be in the parents DS RRset. It 310 allows the Child to present DS records and / or DNSKEY records (for 311 those parents who would rather generate the DS records for their 312 children). 314 The CDS / CDNSKEY record is published in the child zone and gives the 315 child control of what is published for it in the parental zone. The 316 CDS / CDNSKEY RRset expresses what the child would like the DS RRset 317 to look like after the change; it is a "replace" operation, and it is 318 up to the consumer of the records to translate that into the 319 appropriate add/delete operations in the registration systems (and in 320 the case of CDNSKEY, to generate the DS from the DNSKEY). 322 [RFC Editor: Please remove this paragraph before publication] Version 323 -04 of this document defined a new record (CTA) that could hold 324 either a DS or a DNSKEY record (with a selector to differentiate 325 between them). ] 327 3.1. CDS Resource Record Format 329 The wire and presentation format of the CDS ("Child DS") record is 330 identical to the DS record [RFC4034]. IANA has allocated RR code 59 331 for the CDS record via expert review [I-D.ds-publish]. 333 No special processing is performed by authoritative servers or by 334 revolvers, when serving or resolving. For all practical purposes CDS 335 is a regular RR type. 337 3.2. CDNSKEY Resource Record Format 339 The wire and presentation format of the CDNSKEY ("Child DNSKEY") 340 record is identical to the DNSKEY record. 342 No special processing is performed by authoritative servers or by 343 revolvers, when serving or resolving. For all practical purposes 344 CDNSKEY is a regular RR type. 346 4. Automating DS maintainance with CDS/CDNSKEY records 348 CDS/CDNSKEY records are intended to be "consumed" by delegation trust 349 maintainers. The use of CDS/CDNSKEY is optional. 351 Some parents prefer to accept DNSSEC key information in DS format, 352 some parents prefer to accept it in DNSKEY format, and calculate the 353 DS record on the child's behalf. Each method has pros and cons, both 354 technical and policy. This solution is DS vs DNSKEY agnostic, and 355 allows operation with either. 357 If the child knows what the parent prefers, they can publish the 358 parent's preferred record type. If the child does not know (or 359 simply chooses to), they can publish both CDS and CDNSKEY. If the 360 child publishes both, they SHOULD have matching CDS records for each 361 CDNSKEY record. The parent should use whichever one they choose, but 362 SHOULD NOT query for both and perform consistency checks between the 363 CDS and CDNSKEY records. 365 [Editor note: It is not an error for a child to have published CDS 366 records and not have CDNSKEYs that hash to those records, nor for 367 there to be CDNSKEY records without matching DS records. This is 368 because a child might have been publishing CDS records and then the 369 parent's policy changes to require CDNSKEY records. The child might 370 forget to remove the CDS, etc. This avoids all sorts of error 371 conditions / complexity, etc.] 373 4.1. CDS / CDNSKEY processing rules 375 Absence of CDS / CDNSKEY in child signals "No change" to the current 376 DS set. Following acceptance rules are placed on the CDS / CDNSKEY 377 records as follows: 379 o Location: "the CDS / CDNSKEY record MUST be at the child zone 380 apex". 382 o Signer: "MUST be signed with a key that is represented in both the 383 current DNSKEY and DS RRset's." 385 o Continuity: "SHOULD NOT break the current delegation if applied to 386 DS RRset" 388 If any these conditions fail the CDS / CDNSKEY record MUST be 389 ignored. 391 5. Child's CDS / CDNSKEY Publication 393 Child DNS Operator SHOULD only publish a CDS or CDNSKEY RRset when it 394 wants to make a change to the DS RRset in the Parent. The CDS / 395 CDNSKEY RRset SHOULD be compliant with the rules in Section 4.1. 396 When the Parent DS is "in-sync" with the CDS, the Child DNS Operator 397 SHOULD/MUST delete the CDS RRset. Note that if the child has 398 published a DNSKEY RR in the CDS, it will have to calculate the DS 399 (using the requested digest algorithm) to do the comparison. 401 A child MAY publish both CDS and CDNSKEY. If a child chooses to 402 publish both, it SHOULD attempt to maintain consistency (a matching 403 CDS for each CDNSKEY) 405 6. Parent side CDS / CDNSKEY Consumption 407 The CDS / CDNSKEY RRset MAY be used by the Parental Agent to update 408 the DS RRset in the parent zone. The Parental Agent for this uses a 409 tool that understands the CDS / CDNSKEY signing rules from 410 Section 4.1 so it may not be able to use a standard validator. 411 Parent SHOULD treat the Continuity rule as "MUST". 413 The parent MUST choose to accept either CDS or CDNSKEY records, and 414 MUST NOT expect there to be both. A parent SHOULD NOT perform a 415 consistency check between CDS and CDNSKEY (other than for 416 informational / debugging use). 418 6.1. Detecting a changed CDS / CDNSKEY 420 How the Parental Agent gets the CDS / CDNSKEY record may differ, 421 below are two examples as how this can take place. 423 Polling The Parental Agent operates a tool that periodically checks 424 each of the children that has a DS record to see if there is a 425 CDS or CDNSKEY record. 427 Pushing The delegation user interface has a button {Fetch DS} when 428 pushed preforms the CDS / CDNSKEY processing. If the Parent 429 zone does not contain DS for this delegation then the "push" 430 MUST be ignored. 432 In either case the Parental Agent MAY apply additional rules that 433 defer the acceptance of a CDS / CDNSKEY change, these rules may 434 include a condition that the CDS / CDNSKEY remains in place and valid 435 for some time period before it is accepted. It may be appropriate in 436 the "Pushing" case to assume that the Child is ready and thus accept 437 changes without delay. 439 6.1.1. CDS / CDNSKEY Polling 441 This is the only defined use of CDS / CDNSKEY in this document. 442 There are limits to the saleability of polling techniques, thus some 443 other mechanism is likely to be specified later that addresses CDS / 444 CDNSKEY usage in the situation where polling does not scale to. 445 Having said that Polling will work in many important cases like 446 enterprises, universities, small TLDs etc. In many regulatory 447 environments the registry is prohibited from talking to the 448 registrant. In most these cases the registrant has a business 449 relationship with the registrar, and so the registrar can offer this 450 as a service. 452 If the CDS / CDNSKEY RRset does not exist, the Parental Agent MUST 453 take no action. Specifically it MUST NOT delete or alter the 454 existing DS RRset. 456 6.1.2. Other mechanisms 458 It is assume that other mechanisms will be implemented to trigger the 459 parent to look for an updated CDS. As the CDS RR is validated with 460 DNSSEC, these mechanisms can be unauthenticated (for example, a child 461 could call his parent and request the CDS action be performed, an 462 unauthenticated POST could be made to a webserver (with rate- 463 limiting), etc.) 465 Other documents can specify the trigger conditions. 467 6.2. Using the new CDS / CDNSKEY records 469 Regardless of how the Parental Agent detected changes to a CDS / 470 CDNSKEY RR, the Parental Agent MUST use a DNSSEC validator to obtain 471 a validated CDS / CDNSKEY RRset from the Child zone. It would be a 472 good idea if the Parental Agent checked all NS RRs listed at the 473 delegation. However, due to the use of technologies such as load 474 balancing and anycast, this should not be taken as proof that the new 475 CDS / CDNSKEY is present on all nodes serving the Child zone. 477 The Parental Agent MUST ensure that old versions of the CDS / CDNSKEY 478 RRset do not overwrite newer versions. This MAY be accomplished by 479 checking that the signature inception in the RRSIG for CDS / CDNSKEY 480 is newer and/or the serial number on the child's SOA is greater. 481 This may require the Parental Agent to maintain some state 482 information. 484 The Parental Agent MAY take extra security measures. For example, to 485 mitigate the possibility that a Child's key signing key has been 486 compromised, the Parental Agent may, for example, inform (by email or 487 other methods ) the Child DNS operator of the change. However the 488 precise out-of-band measures that a parent zone SHOULD take are 489 outside the scope of this document. 491 Once the Parental Agent has obtained a valid CDS / CDNSKEY it MAY 492 double check the publication rules from section 4.1. In particular 493 the Parental Agent MUST double check the Continuity rule and do its 494 best not to invalidate the Child zone. Once checked and if the CDS / 495 CDNSKEY and DS "differ" it may apply the changes to the parent zone. 496 If the parent consumes CDNSKEY, the parent should calculate the DS 497 before doing this comparison. 499 6.2.1. Parent calculates DS 501 There are cases where the Parent wants to calculate the DS record due 502 to policy reasons. In this case, the Child publishes CDNSKEY records 503 containing DNSKEYs. 505 The parent calculates the DS records on behalf of the children. The 506 DNS Parent needs to publish guidelines for the children as to what 507 digest algorithms are acceptable in the CDS record. 509 When a Parent operates in "calculate DS" mode it can operate in one 510 of two sub-modes 512 full i.e. it only publishes DS records it calculates from DNSKEY 513 records, 515 augment i.e. it will make sure there are DS records for the digest 516 algorithm(s) it requires(s). 518 Implications on Parental Agent are that the CDNSKEY and DS are not 519 exactly the same after update thus it needs to take that into 520 consideration when checking CDNSKEY records. Same goes for the Child 521 Operator, it needs to be able to detect that the new DS RRset is 522 "equivalent" to the current CDNSKEY RRset, thus it can remove the 523 CDNSKEY RRset. 525 7. IANA Considerations 527 IANA has assigned RR Type code 59 for CDS. This was done for an 528 earlier version of this document[I-D.ds-publish] This document is to 529 become the reference for CDS RRtype. 531 IANA is requested to assign another RR Type for the CDNSKEY. 533 8. Privacy Considerations 535 All of the information handled / transmitted by this protocol is 536 public information published in the DNS. 538 9. Security Considerations 540 This work is for the normal case, when things go wrong there is only 541 so much that automation can fix. 543 If child breaks DNSSEC validation by removing all the DNSKEYs that 544 are represented in the DS set its only repair actions are to contact 545 the parent or restore the DNSKEYs in the DS set. 547 In the event of a compromise of the server or system generating 548 signatures for a zone, an attacker might be able to generate and 549 publish new CDS records. The modified CDS records will be picked up 550 by this technique and so may allow the attacker to extend the 551 effective time of his attack. If there a delay in accepting changes 552 to DS, as in RFC5011, then the attacker needs to hope his activity is 553 not detected before the DS in parent is changed. If this type of 554 change takes place, the child need to contact the parent (possibly 555 via a registrar web interface) and remove any compromised DS keys. 557 A compromise of the account with the parent (e.g. registrar) will not 558 be mitigated by this technique, as the "new registrant" can delete/ 559 modify the DS records at will. 561 While it may be tempting, this SHOULD NOT be used for initial 562 enrollment of keys since there is no way to ensure that the initial 563 key is the correct one. If is used, strict rules for inclusion of 564 keys like hold down times, challenge data inclusion etc., ought to be 565 used, along with some kind of challenge mechanism. 567 The CDS RR type should allow for enhanced security by simplifying 568 process. Since rollover is automated, updating a DS RRset by other 569 means may be regarded as unusual and subject to extra security 570 checks. 572 If there is a failure in applying changes in child zone to all DNS 573 servers listed in either parent or child NS set it is possible that 574 the Parental agent may get confused either not perform action because 575 it gets different answers on different checks or CDS validation 576 fails. In the worst case Parental Agent performs an action reversing 577 a prior action but after the child signing system decides to take the 578 next step in rollover, resulting in a broken delegation. 580 DNS is a loosely coherent distributed database with local caching; 581 therefore it is important to allow old information to expire from 582 caches before deleting DS or DNSKEY records. Similarly, it is 583 important to allow new records to propagate through the DNS before 584 use, see [RFC6781] and [I-D.key-time] 586 It is common practice for users to outsource their DNS hosting to a 587 3rd party DNS provider. In order for that provider to be able to 588 maintain the DNSSEC information some users give the provider their 589 registrar login credentials (which obviously has negative security 590 implications). Deploying the solution described in this document 591 allows the 3rd party DNS provider to maintain the DNSSEC information 592 without giving them the registrar credentials, thereby improving 593 security. 595 By automating the maintenance of the DNSSEC key information (and 596 removing humans from the process) we expect to decrease the number of 597 DNSSEC related outages, which should increase DNSSEC deployment. 599 10. Acknowledgements 601 We would like to thank a large number of folk, including: Mark 602 Andrews, Joe Abley, Jaap Akkerhuis, Roy Arends, Doug Barton, Brian 603 Dickinson, Paul Ebersman, Tony Finch, Patrik Faltsrom, Jim Galvin, 604 Paul Hoffman, Olaf Kolkman, Cricket Liu, Stephan Lagerholm, Matt 605 Larson, Marco Sanz, Antoin Verschuren, Suzanne Woolf, Paul Wouters, 606 Matthijs Meeking, John Dickinson, Timothe Litt and Edward Lewis. 608 Special thanks to Wes Hardaker for contributing significant text and 609 creating the complementary (CSYNC) solution, and to Paul Hoffman for 610 some text. 612 There were a number of other folk with whom we discussed this, 613 apologies for not remembering everyone. 615 11. References 616 11.1. Normative References 618 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 619 Requirement Levels", BCP 14, RFC 2119, March 1997. 621 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 622 Rose, "DNS Security Introduction and Requirements", RFC 623 4033, March 2005. 625 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 626 Rose, "Resource Records for the DNS Security Extensions", 627 RFC 4034, March 2005. 629 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 630 Rose, "Protocol Modifications for the DNS Security 631 Extensions", RFC 4035, March 2005. 633 [RFC5011] StJohns, M., "Automated Updates of DNS Security (DNSSEC) 634 Trust Anchors", STD 74, RFC 5011, September 2007. 636 [RFC6781] Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC 637 Operational Practices, Version 2", RFC 6781, December 638 2012. 640 11.2. Informative References 642 [I-D.auto-cpsync] 643 Mekking, W., "Automated (DNSSEC) Child Parent 644 Synchronization using DNS UPDATE", draft-mekking-dnsop- 645 auto-cpsync-01 (work in progress), December 2010. 647 [I-D.csync] 648 Hardaker, W., "Child To Parent Synchronization in DNS", 649 draft-hardaker-dnsop-csync-02 (work in progress), July 650 2013. 652 [I-D.ds-publish] 653 Barwood, G., "DNS Transport", draft-barwood-dnsop-ds- 654 publish-02 (work in progress), June 2011. 656 [I-D.key-time] 657 Mekking, W., "DNSSEC Key Timing Considerations", draft- 658 ietf-dnsop-dnssec-key-timing-03 (work in progress), July 659 2012. 661 [RFC5730] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)", 662 STD 69, RFC 5730, August 2009. 664 [RFC5910] Gould, J. and S. Hollenbeck, "Domain Name System (DNS) 665 Security Extensions Mapping for the Extensible 666 Provisioning Protocol (EPP)", RFC 5910, May 2010. 668 Appendix A. RRR background 670 In the RRR world, the different parties are frequently from different 671 organizations. In the single enterprise world there are also 672 organizational/geographical/cultural separations that affect how 673 information flows from a Child to the parent. 675 Due to the complexity of the different roles and interconnections, 676 automation of delegation information has been punted in the past. 677 There have been some proposals to automate this, in order to improve 678 the reliability of the DNS. These proposals have not gained enough 679 traction to become standards. 681 For example in many of the TLD cases there is the RRR model 682 (Registry, Registrar and Registrant). The Registry operates DNS for 683 the TLD, the Registrars accept registrations and place information 684 into the Registries database. The Registrant only communicates with 685 the Registrar; frequently the Registry is not allowed to communicate 686 with the Registrant. In that case as far as the registrant is 687 concerned the Registrar == Parent. 689 In many RRR cases the Registrar and Registry communicate via 690 EPP[RFC5730] and use the EPP DNSSEC extension [RFC5910]. In a number 691 of ccTLDs there are other mechanisms in use as well as EPP, but in 692 general there seems to be a movement towards EPP usage when DNSSEC is 693 enabled in the TLD. 695 Appendix B. Changes / Author Notes. 697 [RFC Editor: Please remove this section before publication ] 699 WG-00 to WG-01 701 o Addressed Vancouver: "Paul Hoffmann: NOT ready for WGLC. None of 702 the 2 documents explain why there is a split between the two 703 strategies." Thanks to Paul for providing text. 705 From -05 to WG-00: 707 o Nothing rchanged, resubmit under new name. 709 From 04 to 05 711 o Renamed the record back to CDS. 713 o 715 From 03 to 04. 717 o Added text explaining that CDS and CSYNC complement each other, 718 not replace or compete. 720 o Changed format of record to be to allow the 721 publication of DS **or** DNSKEY. 723 o Bunch of text changed to cover the above. 725 o Added a bit more text on the polling scaling stuff, expecation 726 that other triggers will be documented, 728 From 02 to 03 730 o Applied comments by Matthijs Mekking 732 o Incorporated suggestions from Edward Lewis about structure 734 o Reworked structure to be easier for implementors to follow 736 o Applied many suggestions from a wonderful thorough review by John 737 Dickinson 739 o Removed the going Unsigned option 741 From 01 to 02 743 o Major restructuring to facilitate easier discussion 745 o Lots of comments from DNSOP mailing list incorporated, including 746 making draft DNSKEY/DS neutral, explain different relationships 747 that exists, 749 o added more people to acks. 751 o added description of enterprise situations 753 o Unified on using Parental Agent over Parental Representative 755 o Removed redundant text when possible 757 o Added text to explain what can go wrong if not all child DNS 758 servers are in sync. 760 o Reference prior work by Matthijs Mekking 761 o Added text when parent calculates DS from DNSKEY 763 From - to -1. 765 o Removed from section .1: "If a child zone has gone unsigned, i.e. 766 no DNSKEY and no RRSIG in the zone, the parental representative 767 MAY treat that as intent to go unsigned. (NEEDS DISCUSSION)." 768 Added new text at end. -- suggestion by Scott Rose 20/Feb/13. 770 o Added some background on the different DNS Delegation operating 771 situations and how they affect interaction of parties. This moved 772 some blocks of text from later sections into here. 774 o Number of textual improvements from Stephan Lagerholm 776 o Added motivation why CDS is needed in CDS definition section 778 o Unified terminology in the document. 780 o Much more background 782 Authors' Addresses 784 Warren Kumari 785 Google 786 1600 Amphitheatre Parkway 787 Mountain View, CA 94043 788 US 790 Email: warren@kumari.net 792 Olafur Gudmundsson 793 Shinkuro Inc. 794 4922 Fairmont Av, Suite 250 795 Bethesda, MD 20814 796 USA 798 Email: ogud@ogud.com 800 George Barwood 801 33 Sandpiper Close 802 Gloucester GL2 4LZ 803 United Kingdom 805 Email: george.barwood@blueyonder.co.uk