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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: October 18, 2014 Shinkuro Inc. 6 G. Barwood 8 April 16, 2014 10 Automating DNSSEC Delegation Trust Maintenance 11 draft-ietf-dnsop-delegation-trust-maintainance-09 13 Abstract 15 This document describes a method to allow DNS operators to more 16 easily update DNSSEC Key Signing Keys using the 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 October 18, 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 . . . . . . . . . . . . . . . 8 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. 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 . . . . . . . . . . . . . . . . . . . . . . 14 80 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 81 11.1. Normative References . . . . . . . . . . . . . . . . . . 14 82 11.2. Informative References . . . . . . . . . . . . . . . . . 15 83 Appendix A. RRR background . . . . . . . . . . . . . . . . . . . 15 84 Appendix B. Changes / Author Notes. . . . . . . . . . . . . . . 16 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 87 1. Introduction 89 The first time a DNS operator signs a zone, they need to communicate 90 the keying material to their parent through some out-of-band method 91 to complete the chain of trust. Depending on the desires of the 92 parent, the child might send their DNSKEY record, a DS record, or 93 both. 95 Each time the child changes the key that is represented in the 96 parent, the updated and/or deleted key information has to be 97 communicated to the parent and published in the parent's zone. How 98 this information is sent to the parent depends on the relationship 99 the child has with the parent. In many cases this is a manual 100 process, and not an easy one. For each key change, there may be up 101 to two interactions with the parent. Any manual process is 102 susceptible to mistakes and/or errors. In addition, due to the 103 annoyance factor of the process, operators may avoid changing keys or 104 skip needed steps to publish the new DS at the parent. 106 DNSSEC provides data integrity to information published in DNS; thus 107 DNS publication can be used to automate maintenance of delegation 108 information. This document describes a method to automate 109 publication of subsequent DS records, after the initial one has been 110 published. 112 Readers are expected to be familiar with DNSSEC, including [RFC4033], 113 [RFC4034], [RFC4035], [RFC5011] and [RFC6781]. 115 This document is a compilation of two earlier drafts: draft-barwood- 116 dnsop-ds-publish[I-D.ds-publish] and draft-wkumari-dnsop-ezkeyroll. 118 This document outlines a technique in which the parent periodically 119 (or upon request) polls its signed children and automatically publish 120 new DS records. To a large extent, the procedures this document 121 follows are as described in [RFC6781] section 4.1.2. 123 This technique is designed to be friendly both to fully automated 124 tools and humans. Fully automated tools can perform all the actions 125 needed without human intervention, and thus can monitor when it is 126 safe to move to the next step. 128 The solution described in this document only allows transferring 129 information about DNSSEC keys (DS and DNSKEY) from the child to the 130 parental agent. It lists exactly what the parent should publish, and 131 allows for publication of stand-by keys. A different protocol, 132 [I-D.csync], can be used to maintain other important delegation 133 information, such as NS and glue. These two protocols have been kept 134 as separate solutions because the problems are fundamentally 135 different, and a combined solution is overly complex. 137 This document describes a method for automating maintanance of the 138 delegation trust information, and proposes a polled / periodic 139 trigger for simplicity. Some users may prefer a different trigger, 140 for example a button on a webpage, a REST interface or a DNS NOTIFY. 141 These alternate / additional triggers are not discussed in this 142 document. 144 This proposal does not include all operations needed for the 145 maintenance of DNSSEC key material, specifically the initial 146 introduction or complete removal of all keys. Because of this, 147 alternate communications mechanisms must always exist, potentially 148 introducing more complexity. 150 1.1. Terminology 152 The terminology we use is defined in this section. 154 Highlighted roles: 156 o Child: "The entity on record that has the delegation of the domain 157 from the parent" 159 o Parent: "The domain in which the child is registered" 161 o Child DNS Operator: "The entity that maintains and publishes the 162 zone information for the child DNS" 164 o Parental Agent: "The entity that the child has relationship with, 165 to change its delegation information" 167 o Provisioning system: "A system that the operator of the master DNS 168 server operates to maintain the information published in the DNS. 169 This includes the systems that sign the DNS data" 171 RRR is our shorthand for Registry/Registrar/Registrant model of 172 parent child relationship see Appendix A for more. 174 1.2. Requirements Notation 176 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 177 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 178 document are to be interpreted as described in [RFC2119]. 180 2. Background 182 2.1. DNS Delegations 184 DNS operation consists of delegations of authority. For each 185 delegation there are (most of the time) two parties: the parent and 186 the child. 188 The parent publishes information about the delegations to the child; 189 for the name servers it publishes an NS [RFC1035] RRset that lists a 190 hint for name servers that are authoritative for the child. The 191 child also publishes a NS RRset, and this set is the authoritative 192 list of name servers to the child zone. 194 The second RRset the parent sometimes publishes is the DS [RFC4034] 195 set. The DS RRset provides information about the DNSKEY(s) that the 196 child has told the parent it will use to sign its DNSKEY RRset. In 197 DNSSEC trust relationship between zones is provided by the following 198 chain: 200 parent DNSKEY --> DS --> child DNSKEY. 202 A prior proposal [I-D.auto-cpsync] suggested that the child send an 203 "update" to the parent via a mechanism similar to Dynamic Update. 204 The main issue became: How does the child find the actual parental 205 agent/server to send the update to? While that could have been 206 solved via technical means, it failed to each consensus. There is 207 also a similar proposal in [I-D.parent-zones]. 209 As the DS record can only be present at the parent ( [RFC4034]), some 210 other method is needed to automate which DNSKEYs are picked to be 211 represented in the parent zone's DS records. One possibility is to 212 use flags in the DNSKEY record. If the SEP bit is set, this 213 indicates that the DNSKEY is intended for use as a secure entry 214 point. This DNSKEY signs the DNSKEY RRset, and the Parental Agent 215 can calculate DS records based on that. But this fails to meet some 216 operating needs, including the child having no influence what DS 217 digest algorithms are used and DS records can only be published for 218 keys that are in the DNSKEY RRset, and thus this technique would not 219 be compatible with Double-DS ( [RFC6781] ) key rollover. 221 2.2. Relationship Between Parent and Child DNS Operator 223 In practical application, there are many different relationships 224 between the parent and Child DNS Operators. The type of relationship 225 affects how the Child DNS Operator communicates with the parent. 226 This section will highlight some of the different situations, but is 227 by no means a complete list. 229 Different communication paths: 231 o Direct/API: The child can change the delegation information via 232 automated/scripted means. EPP[RFC5730], used by many TLDs is an 233 example of this. Another example is the web service's 234 programmatic interfaces that Registrars make available to their 235 Resellers. 237 o User Interface: The Child uses a (web) site set up by the Parental 238 Agent for updating delegation information. 240 o Indirect: The communication has to be transmitted via out-of-band 241 between two parties, such as by email or telephone. This is 242 common when the Child's DNS operator is neither the child itself 243 nor the Registrar for the domain but a third party. 245 o Multi-step Combinations: The information flows through an 246 intermediary. It is possible, but unlikely, that all the steps 247 are automated via API's and there are no humans are involved. 249 A domain name holder (Child) may operate its own DNS servers or 250 outsource the operation. While we use the word parent as a singular, 251 parent can consist of single entity or a composite of many discrete 252 parts that have rules and roles. We refer to the entity that the 253 child corresponds with as the Parent. 255 In some cases an organization may delegate parts of its name-space to 256 be operated by a group that is not the same as that which operates 257 the organization's DNS servers. In this case the flow of information 258 is frequently handled in either an ad hoc manner or via some 259 corporate mechanism; this can range from email to fully-automated 260 operation. 262 2.2.1. Solution Space 264 This document is aimed at the cases in which there is a separation 265 between the child and parent. 267 A further complication is when the Child DNS Operator is not the 268 Child. There are two common cases of this: 270 a) The Parental Agent (e.g. registrar) handles the DNS operation. 272 b) A third party takes care of the DNS operation. 274 If the Parental Agent is the DNS operator, life is much easier; the 275 Parental Agent can inject any delegation changes directly into the 276 Parent's Provisioning system. The techniques described below are not 277 needed in the case when Parental Agent is the DNS operator. 279 In the case of a third party DNS operator, the Child either needs to 280 relay changes in DNS delegation or give the Child DNS Operator access 281 to its delegation/registration account. 283 Some parents want the child to express their DNSKEYS in the form of 284 DS records, while others want to receive the DNSKEY records and 285 calculate the DS records themselves. There is no consensus on which 286 method is better; both have good reasons to exist. This solution is 287 DS vs DNSKEY agnostic, and allows operation with either. 289 2.2.2. DNSSEC key change process 291 After a Child DNS Operator first signs the zone, there is a need to 292 interact with the Parent, for example via a delegation account 293 interface, to "upload / paste-in the zone's DS information". This 294 action of logging in through the delegation account user interface 295 authenticates that the user is authorized to change delegation 296 information for the child published in the parent zone. In the case 297 where the Child DNS Operator does not have access to the registration 298 account, the Child needs to perform the action. 300 At a later date, the Child DNS Operator may want to publish a new DS 301 record in the parent, either because they are changing keys, or 302 because they want to publish a stand-by key. This involves 303 performing the same process as before. Furthermore when this is a 304 manual process with cut and paste, operational mistakes will happen 305 -- or worse, the update action is not performed at all. 307 The Child DNS Operator may also introduce new keys, and can do so 308 when old keys exist and can be used. The Child may also remove old 309 keys, but this document does not support removing all keys. This is 310 to avoid making signed zones unsigned. The Child may not enroll the 311 initial key or introduce a new key when there are no old keys that 312 can be used (without some additional, out of band, validation of the 313 keys), because there is no way to validate the information. 315 3. CDS / CDNSKEY (Child DS/ Child DNSKEY) Record Definitions 317 This document specifies two new DNS resource records, CDS and 318 CDNSKEY. These records are used to convey, from one zone to its 319 parent, the desired contents of the zone's DS resource record set 320 residing in the parent zone. 322 The CDS / CDNSKEY resource records are published in the child zone 323 and gives the child control of what is published for it in the 324 parental zone. The CDS / CDNSKEY RRset expresses what the child 325 would like the DS RRset to look like after the change; it is a 326 "replace" operation, and it is up to the consumer of the records to 327 translate that into the appropriate add/delete operations in the 328 provisioning systems (and in the case of CDNSKEY, to generate the DS 329 from the DNSKEY). If no CDS / CDNSKEY RRset is present in child, 330 this means that no change is needed. 332 [[RFC Editor: Please remove this paragraph before publication] 333 Version -04 of the ID that became this working group document (http:/ 334 /tools.ietf.org/id/draft-kumari-ogud-dnsop-cds-04.txt) defined a new 335 record (CTA) that could hold either a DS or a DNSKEY record (with a 336 selector to differentiate between them). In a shocking development, 337 there was almost full consensus that this was horrid :-) ] 339 3.1. CDS Resource Record Format 341 The wire and presentation format of the CDS ("Child DS") resource 342 record is identical to the DS record [RFC4034]. IANA has allocated 343 RR code 59 for the CDS resource record via expert review 344 [I-D.ds-publish]. The CDS RR uses the same registries as DS for its 345 fields. 347 No special processing is performed by authoritative servers or by 348 revolvers, when serving or resolving. For all practical purposes CDS 349 is a regular RR type. 351 3.2. CDNSKEY Resource Record Format 353 The wire and presentation format of the CDNSKEY ("Child DNSKEY") 354 resource record is identical to the DNSKEY record. IANA has 355 allocated RR code TBA1 for the CDNSKEY resource record via expert 356 review. The CDNSKEY RR uses the same registries as DNSKEY for its 357 fields. 359 No special processing is performed by authoritative servers or by 360 revolvers, when serving or resolving. For all practical purposes 361 CDNSKEY is a regular RR type. 363 4. Automating DS Maintainance With CDS/CDNSKEY records 365 CDS/CDNSKEY resource records are intended to be "consumed" by 366 delegation trust maintainers. The use of CDS/CDNSKEY is optional. 368 The child SHOULD publish both CDS and CDNSKEY resource records. If 369 the child knows which the parent consumes, it MAY choose to only 370 publish that record type (for example, some children wish the parent 371 to publish a DS, but they wish to keep the DNSKEY "hidden" until 372 needed). If the child publishes both, the two RRsets MUST match in 373 content. 375 4.1. CDS / CDNSKEY Processing Rules 377 If there are no CDS / CDNSKEY RRset in the child, this signals that 378 no change should be made to the current DS set. This means that, 379 once the child and parent are in sync, the Child DNS Operator MAY 380 remove all CDS and CDNSKEY resource records from the zone. 382 Following acceptance rules are placed on the CDS / CDNSKEY resource 383 records as follows: 385 o Location: "the CDS / CDNSKEY resource records MUST be at the child 386 zone apex". 388 o Signer: "MUST be signed with a key that is represented in both the 389 current DNSKEY and DS RRset's." 391 o Continuity: "MUST NOT break the current delegation if applied to 392 DS RRset" 394 If any these conditions fail the CDS / CDNSKEY resource record MUST 395 be ignored. 397 5. CDS / CDNSKEY Publication 399 Child DNS Operator publishes a CDS and / or CDNSKEY resource records. 400 In order to be valid, the CDS / CDNSKEY RRset MUST be compliant with 401 the rules in Section 4.1. When the Parent DS is "in-sync" with the 402 CDS / CDNSKEY resource records, the Child DNS Operator MAY delete the 403 CDS / CDNSKEY record(s); the child can determine if this is the case 404 by quering for DS records in the parent. Note that if the child has 405 published a CDNSKEY RR, the Parent will have to calculate the DS 406 (using the requested digest algorithm) to do the comparison. 408 6. Parent Side CDS / CDNSKEY Consumption 410 The CDS / CDNSKEY RRset SHOULD be used by the Parental Agent to 411 update the DS RRset in the parent zone. The Parental Agent for this 412 uses a tool that understands the CDS / CDNSKEY signing rules from 413 Section 4.1 so it may not be able to use a standard validator. 415 The parent MUST choose to use either CDNSKEY or CDS resource records 416 as their default updating mechanism. The parent MAY only accept 417 either CDNSKEY or CDS, but it MAY also accept both, so it can use the 418 other in the absence of the default updating mechanism, but it MUST 419 NOT expect there to be both. 421 6.1. Detecting a Changed CDS / CDNSKEY 423 How the Parental Agent gets the CDS / CDNSKEY RRset may differ, below 424 are two examples as how this can take place. 426 Polling The Parental Agent operates a tool that periodically checks 427 each of the children that has a DS record to see if there is a 428 CDS or CDNSKEY RRset. 430 Pushing The delegation user interface has a button {Fetch DS} when 431 pushed preforms the CDS / CDNSKEY processing. If the Parent 432 zone does not contain DS for this delegation then the "push" 433 SHOULD be ignored. If the Parental Agent displays the contents 434 of the CDS / CDSNKEY to the user and gets confirmation that 435 this represents their key, the Parental Agent MAY use this for 436 initial enrolment (when the Parent zone does not contain the DS 437 for this delgation). 439 In either case the Parental Agent MAY apply additional rules that 440 defer the acceptance of a CDS / CDNSKEY change, these rules may 441 include a condition that the CDS / CDNSKEY remains in place and valid 442 for some time period before it is accepted. It may be appropriate in 443 the "Pushing" case to assume that the Child is ready and thus accept 444 changes without delay. 446 6.1.1. CDS / CDNSKEY Polling 448 This is the only defined use of CDS / CDNSKEY resource records in 449 this document. There are limits to the scaleability of polling 450 techniques, thus some other mechanism is likely to be specified later 451 that addresses CDS / CDNSKEY resource recod usage in the situation 452 where polling does not scale to. Having said that Polling will work 453 in many important cases such as enterprises, universities and smaller 454 TLDs. In many regulatory environments the registry is prohibited 455 from talking to the registrant. In most of these cases the 456 registrant has a business relationship with the registrar, and so the 457 registrar can offer this as a service. 459 If the CDS / CDNSKEY RRset does not exist, the Parental Agent MUST 460 take no action. Specifically it MUST NOT delete or alter the 461 existing DS RRset. 463 6.1.2. Other Mechanisms 465 It is assumed that other mechanisms will be implemented to trigger 466 the parent to look for an updated CDS / CDNSKEY RRsets. As the CDS / 467 CDNSKEY resource records are validated with DNSSEC, these mechanisms 468 can be unauthenticated (for example, a child could telephone its 469 parent and request that they process the new CDS or CDNSKEY resource 470 records or an unauthenticated POST could be made to a webserver (with 471 rate-limiting).) 473 Other documents can specify the trigger conditions. 475 6.2. Using the New CDS / CDNSKEY Records 477 Regardless of how the Parental Agent detected changes to a CDS / 478 CDNSKEY RRset, the Parental Agent SHOULD use a DNSSEC validator to 479 obtain a validated CDS / CDNSKEY RRset from the Child zone. The only 480 exception to this is if the parent perfoms some additional validation 481 on the data to confirm that it is the "correct" key. This behavior 482 is NOT RECOMMENDED. 484 The Parental Agent MUST ensure that previous versions of the CDS / 485 CDNSKEY RRset do not overwrite more recent versions. This MAY be 486 accomplished by checking that the signature inception in the RRSIG 487 for CDS / CDNSKEY RRset is later and/or the serial number on the 488 child's SOA is greater. This may require the Parental Agent to 489 maintain some state information. 491 The Parental Agent MAY take extra security measures. For example, to 492 mitigate the possibility that a Child's key signing key has been 493 compromised, the Parental Agent may, for example, inform (by email or 494 other methods ) the Child DNS Operator of the change. However the 495 precise out-of-band measures that a parent zone SHOULD take are 496 outside the scope of this document. 498 Once the Parental Agent has obtained a valid CDS / CDNSKEY RRset it 499 MUST check the publication rules from section 4.1. In particular the 500 Parental Agent MUST check the Continuity rule and do its best not to 501 invalidate the Child zone. Once checked and if the information in 502 the CDS / CDNSKEY and DS differ it may apply the changes to the 503 parent zone. If the parent consumes CDNSKEY, the parent should 504 calculate the DS before doing this comparison. 506 6.2.1. Parent Calculates DS 508 There are cases where the Parent wants to calculate the DS record due 509 to policy reasons. In this case, the Child publishes CDNSKEY records 510 and the parent calculates the DS records on behalf of the children. 512 When a Parent operates in "calculate DS" mode it can operate in one 513 of two sub-modes 515 full it only publishes DS records it calculates from DNSKEY records, 517 augment it will make sure there are DS records for the digest 518 algorithm(s) it requires(s). 520 In the case where the parent fetches the CDNSKEY RRset and calculate 521 the DS it MAY be the case that the DS published in the parent zone is 522 not identical with the data in the CDS resource record made available 523 by the child. 525 7. IANA Considerations 527 IANA has assigned RR Type code 59 for the CDS resource record. This 528 was done for an earlier version of this document[I-D.ds-publish] This 529 document is to become the reference for CDS RRtype. 531 IANA is requested to assign another RR Type for the CDNSKEY, and to 532 replace TBA1 with this value (currntly 60 is still free, it would be 533 nice if that were assigned...) 535 8. Privacy Considerations 537 All of the information handled / transmitted by this protocol is 538 public information published in the DNS. 540 9. Security Considerations 542 This work is for the normal case; when things go wrong there is only 543 so much that automation can fix. 545 If child breaks DNSSEC validation by removing all the DNSKEYs that 546 are represented in the DS set its only repair actions are to contact 547 the parent or restore the DNSKEYs in the DS set. 549 In the event of a compromise of the server or system generating 550 signatures for a zone, an attacker might be able to generate and 551 publish new CDS resource records. The modified CDS recourse records 552 will be picked up by this technique and so may allow the attacker to 553 extend the effective time of his attack. If there a delay in 554 accepting changes to DS, as in [RFC5011], then the attacker needs to 555 hope his activity is not detected before the DS in parent is changed. 556 If this type of change takes place, the child needs to contact the 557 parent (possibly via a registrar web interface) and remove any 558 compromised DS keys. 560 A compromise of the account with the parent (e.g. registrar) will not 561 be mitigated by this technique, as the "new registrant" can delete/ 562 modify the DS records at will. 564 While it may be tempting, this SHOULD NOT be used for initial 565 enrollment of keys since there is no way to ensure that the initial 566 key is the correct one. If is used, strict rules for inclusion of 567 keys such as hold down times, challenge data inclusion or similar, 568 ought to be used, along with some kind of challenge mechanism. A 569 child cannot use this mechanism to go from signed to unsigned 570 (publishing an empty CDS / CDNSKEY RRset means no-change should be 571 made in the parent). 573 The CDS RR type should allow for enhanced security by simplifying 574 process. Since key change is automated, updating a DS RRset by other 575 means may be regarded as unusual and subject to extra security 576 checks. 578 As this introduces a new mechanism to update information in the 579 parent it MUST be clear who is fetching the records and creating the 580 appropriate records in the parent zone. Specifically some operations 581 may use other mechanisms than what is described here. For example, a 582 registrar may assume that it is maintaining the DNSSEC key 583 information in the registry, and may have this cached. If the 584 registry is fetching the CDS / CDNSKEY RRset then the registry and 585 registrar may have different views of the DNSSEC key material and the 586 result of such a situation is unclear. Therefore, this mechanism 587 SHOULD NOT be use to bypass intermediaries that might cache 588 information and because of that get the wrong state. 590 If there is a failure in applying changes in child zone to all DNS 591 servers listed in either parent or child NS set it is possible that 592 the Parental agent may get confused, either because it gets different 593 answers on different checks or CDS RR validation fails. In the worst 594 case, the Parental Agent performs an action reversing a prior action 595 but after the child signing system decides to take the next step in 596 the key change process, resulting in a broken delegation. 598 DNS is a loosely coherent distributed database with local caching; 599 therefore, it is important to allow old information to expire from 600 caches before deleting DS or DNSKEY records. Similarly, it is 601 important to allow new records to propagate through the DNS before 602 use, see [RFC6781] and [I-D.key-time] 604 It is common practice for users to outsource their DNS hosting to a 605 3rd party DNS provider. In order for that provider to be able to 606 maintain the DNSSEC information some users give the provider their 607 registrar login credentials (which obviously has negative security 608 implications). Deploying the solution described in this document 609 allows the 3rd party DNS provider to maintain the DNSSEC information 610 without giving them the registrar credentials, thereby improving 611 security. 613 By automating the maintenance of the DNSSEC key information (and 614 removing humans from the process), we expect to decrease the number 615 of DNSSEC related outages, which should increase DNSSEC deployment. 617 10. Acknowledgements 619 We would like to thank a large number of folk, including: Mark 620 Andrews, Joe Abley, Jaap Akkerhuis, Roy Arends, Doug Barton, Brian 621 Dickinson, Paul Ebersman, Tony Finch, Jim Galvin, Paul Hoffman, Samir 622 Hussain, Tatuya Jinmei, Olaf Kolkman, Cricket Liu, Stephan Lagerholm, 623 Matt Larson, Marco Sanz, Antoin Verschuren, Suzanne Woolf, Paul 624 Wouters, John Dickinson, Timothe Litt and Edward Lewis. 626 Special thanks to Wes Hardaker for contributing significant text and 627 creating the complementary (CSYNC) solution, and to Patrik Faltstrom, 628 Paul Hoffman, Matthijs Mekking and Mukund Sivaraman for text and in- 629 depth review. 631 There were a number of other folk with whom we discussed this, 632 apologies for not remembering everyone. 634 11. References 636 11.1. Normative References 638 [RFC1035] Mockapetris, P., "Domain names - implementation and 639 specification", STD 13, RFC 1035, November 1987. 641 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 642 Requirement Levels", BCP 14, RFC 2119, March 1997. 644 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 645 Rose, "DNS Security Introduction and Requirements", RFC 646 4033, March 2005. 648 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 649 Rose, "Resource Records for the DNS Security Extensions", 650 RFC 4034, March 2005. 652 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 653 Rose, "Protocol Modifications for the DNS Security 654 Extensions", RFC 4035, March 2005. 656 [RFC5011] StJohns, M., "Automated Updates of DNS Security (DNSSEC) 657 Trust Anchors", STD 74, RFC 5011, September 2007. 659 [RFC6781] Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC 660 Operational Practices, Version 2", RFC 6781, December 661 2012. 663 11.2. Informative References 665 [I-D.auto-cpsync] 666 Mekking, W., "Automated (DNSSEC) Child Parent 667 Synchronization using DNS UPDATE", draft-mekking-dnsop- 668 auto-cpsync-01 (work in progress), December 2010. 670 [I-D.csync] 671 Hardaker, W., "Child To Parent Synchronization in DNS", 672 draft-hardaker-dnsop-csync-02 (work in progress), July 673 2013. 675 [I-D.ds-publish] 676 Barwood, G., "DNS Transport", draft-barwood-dnsop-ds- 677 publish-02 (work in progress), June 2011. 679 [I-D.key-time] 680 Mekking, W., "DNSSEC Key Timing Considerations", draft- 681 ietf-dnsop-dnssec-key-timing-03 (work in progress), July 682 2012. 684 [I-D.parent-zones] 685 Andrews, M., "Updating Parent Zones", draft-andrews-dnsop- 686 update-parent-zones-04 (work in progress), November 2013. 688 [RFC5730] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)", 689 STD 69, RFC 5730, August 2009. 691 [RFC5910] Gould, J. and S. Hollenbeck, "Domain Name System (DNS) 692 Security Extensions Mapping for the Extensible 693 Provisioning Protocol (EPP)", RFC 5910, May 2010. 695 Appendix A. RRR background 697 In the RRR world, the different parties are frequently from different 698 organizations. In the single enterprise world there are also 699 organizational/geographical/cultural separations that affect how 700 information flows from a Child to the parent. 702 Due to the complexity of the different roles and interconnections, 703 automation of delegation information has not yet occured. There have 704 been proposals to automate this, in order to improve the reliability 705 of the DNS. These proposals have not gained enough traction to 706 become standards. 708 For example in many of the TLD cases there is the RRR model 709 (Registry, Registrar and Registrant). The Registry operates DNS for 710 the TLD, the Registrars accept registrations and place information 711 into the Registries database. The Registrant only communicates with 712 the Registrar; frequently the Registry is not allowed to communicate 713 with the Registrant. In that case as far as the registrant is 714 concerned the Registrar == Parent. 716 In many RRR cases the Registrar and Registry communicate via 717 EPP[RFC5730] and use the EPP DNSSEC extension [RFC5910]. In a number 718 of ccTLDs there are other mechanisms in use as well as EPP, but in 719 general there seems to be a movement towards EPP usage when DNSSEC is 720 enabled in the TLD. 722 Appendix B. Changes / Author Notes. 724 [RFC Editor: Please remove this section before publication ] 726 WG-08 to WG-09 728 o New text from Paul Hoffman for the first paragraph of the intro. 730 o ... with a modification from Jaap. 732 WG-07 to WG-08 734 o Incorporated text from Antoin Verschuren at the end of Section 6. 736 o Comments from Paul Hoffman and Tim W 738 WG-06 to WG-07 740 o Incorporated nits / editorial comments from Tim Wicinski. 742 o 744 * Reference for Mark's draft was incorrect, Wes Hardaker doesn't 745 work for ISC :-P 747 * Normalized CDS record / CDS resource record / records / etc. 749 * Language cleanup / nits / poor grammar. 751 * removed "punted" colloquialism. 753 WG-05 to WG-06 755 o Consensus (according to me!) was that mail thread said "Child MAY 756 remove the CDS record". Changed to accomodate. 758 o "The proposal below can operate with both models, but the child 759 needs to be aware of the parental policies." - removed "but the 760 child needs to be aware of the parental policies.". This is no 761 longer true, as we suggest publishing both CDS and CDSNKEY. 763 o Added: "without some additional out of band process" to "The Child 764 may not enroll the initial key or introduce a new key when there 765 are no old keys that can be used (without some additional, out of 766 band, validation of the keys), because there is no way to validate 767 the information." 769 o Added a bit to the IANA section, requesting that TBA1 be replaced 770 with the IANA allocated code. 772 o Removed" Some parents prefer to accept DNSSEC key information in 773 DS format, some parents prefer to accept it in DNSKEY format, and 774 calculate the DS record on the child's behalf. Each method has 775 pros and cons, both technical and policy. This solution is DS vs 776 DNSKEY agnostic, and allows operation with either." from Section 4 777 as it is covered in Section 2.2.1 779 o Remove a bunch of comments from the XML. I was getting tired of 780 scrolling past them. If the authors need them back, they are in 781 SVN commit 47. 783 WG-04 to WG-05 785 o More comments from Patrik, Paul and Ed. 787 o Many nits and fixes from Matthijs Mekking. 789 o Outstanding question: Should we remove the "Child SHOULD remove 790 the CDS record" text? Mail sent to list. 792 WG-03 to WG-04 794 o Large number of comments and changes from Patrik. 796 WG-02 to WG-03 798 o Fixed some references to RFC 5011 - from Samir Hussain. 800 o Fixed some spelling / typos - from Samir Hussain. 802 o A number of clarifiations on the meaning on an empty / non- 803 existant CDS RRset - thanks to JINMEI, Tatuya 805 o Be consistent in mentioning both CDS and CDNSKEY throughout the 806 document. 808 WG-01 to WG-02 810 o Many nits and suggestions from Mukund. 812 o Matthijs: " I still think that it is too strong that the Child DNS 813 Operator SHOULD/MUST delete the CDS RRset when the Parent DS is 814 "in-sync". This should be a MAY" 816 WG-00 to WG-01 818 o Addressed Vancouver: "Paul Hoffmann: NOT ready for WGLC. None of 819 the 2 documents explain why there is a split between the two 820 strategies." Thanks to Paul for providing text. 822 From -05 to WG-00: 824 o Nothing rchanged, resubmit under new name. 826 From 04 to 05 828 o Renamed the record back to CDS. 830 From 03 to 04. 832 o Added text explaining that CDS and CSYNC complement each other, 833 not replace or compete. 835 o Changed format of record to be to allow the 836 publication of DS **or** DNSKEY. 838 o Bunch of text changed to cover the above. 840 o Added a bit more text on the polling scaling stuff, expectation 841 that other triggers will be documented. 843 From 02 to 03 845 o Applied comments by Matthijs Mekking 847 o Incorporated suggestions from Edward Lewis about structure 849 o Reworked structure to be easier for implementors to follow 851 o Applied many suggestions from a wonderful thorough review by John 852 Dickinson 854 o Removed the going Unsigned option 856 From 01 to 02 858 o Major restructuring to facilitate easier discussion 860 o Lots of comments from DNSOP mailing list incorporated, including 861 making draft DNSKEY/DS neutral, explain different relationships 862 that exists, 864 o added more people to acks. 866 o added description of enterprise situations 868 o Unified on using Parental Agent over Parental Representative 870 o Removed redundant text when possible 872 o Added text to explain what can go wrong if not all child DNS 873 servers are in sync. 875 o Reference prior work by Matthijs Mekking 877 o Added text when parent calculates DS from DNSKEY 879 From - to -1. 881 o Removed from section .1: "If a child zone has gone unsigned, i.e. 882 no DNSKEY and no RRSIG in the zone, the parental representative 883 MAY treat that as intent to go unsigned. (NEEDS DISCUSSION)." 884 Added new text at end. -- suggestion by Scott Rose 20/Feb/13. 886 o Added some background on the different DNS Delegation operating 887 situations and how they affect interaction of parties. This moved 888 some blocks of text from later sections into here. 890 o Number of textual improvements from Stephan Lagerholm 892 o Added motivation why CDS is needed in CDS definition section 894 o Unified terminology in the document. 896 o Much more background 898 Authors' Addresses 900 Warren Kumari 901 Google 902 1600 Amphitheatre Parkway 903 Mountain View, CA 94043 904 US 906 Email: warren@kumari.net 908 Olafur Gudmundsson 909 Shinkuro Inc. 910 4922 Fairmont Av, Suite 250 911 Bethesda, MD 20814 912 USA 914 Email: ogud@ogud.com 916 George Barwood 917 33 Sandpiper Close 918 Gloucester GL2 4LZ 919 United Kingdom 921 Email: george.barwood@blueyonder.co.uk