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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Line 519 has weird spacing: '... full it on...' == Line 521 has weird spacing: '...augment it wi...' == The document seems to use 'NOT RECOMMENDED' as an RFC 2119 keyword, but does not include the phrase in its RFC 2119 key words list. -- The document date (April 16, 2014) is 2957 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: draft-ietf-dnsop-dnssec-key-timing has been published as RFC 7583 Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--).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: 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-11 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. The technique described is aimed at delegations in which it 18 is currently hard to move information from the child to parent. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on October 18, 2014. 37 Copyright Notice 39 Copyright (c) 2014 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 56 1.2. Requirements Notation . . . . . . . . . . . . . . . . . . 4 57 2. Background . . . . . . . . . . . . . . . . . . . . . . . . . 4 58 2.1. DNS Delegations . . . . . . . . . . . . . . . . . . . . . 4 59 2.2. Relationship Between Parent and Child DNS Operator . . . 5 60 2.2.1. Solution Space . . . . . . . . . . . . . . . . . . . 6 61 2.2.2. DNSSEC key change process . . . . . . . . . . . . . . 7 62 3. CDS / CDNSKEY (Child DS/ Child DNSKEY) Record Definitions . . 7 63 3.1. CDS Resource Record Format . . . . . . . . . . . . . . . 8 64 3.2. CDNSKEY Resource Record Format . . . . . . . . . . . . . 8 65 4. Automating DS Maintainance With CDS/CDNSKEY records . . . . . 8 66 4.1. CDS / CDNSKEY Processing Rules . . . . . . . . . . . . . 8 67 5. CDS / CDNSKEY Publication . . . . . . . . . . . . . . . . . . 9 68 6. Parent Side CDS / CDNSKEY Consumption . . . . . . . . . . . . 9 69 6.1. Detecting a Changed CDS / CDNSKEY . . . . . . . . . . . . 9 70 6.1.1. CDS / CDNSKEY Polling . . . . . . . . . . . . . . . . 10 71 6.1.2. Other Mechanisms . . . . . . . . . . . . . . . . . . 10 72 6.2. Using the New CDS / CDNSKEY Records . . . . . . . . . . . 11 73 6.2.1. Parent Calculates DS . . . . . . . . . . . . . . . . 11 74 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 75 8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 12 76 9. Security Considerations . . . . . . . . . . . . . . . . . . . 12 77 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 78 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 79 11.1. Normative References . . . . . . . . . . . . . . . . . . 14 80 11.2. Informative References . . . . . . . . . . . . . . . . . 15 81 Appendix A. RRR background . . . . . . . . . . . . . . . . . . . 15 82 Appendix B. Changes / Author Notes. . . . . . . . . . . . . . . 16 83 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 85 1. Introduction 87 The first time a DNS operator signs a zone, they need to communicate 88 the keying material to their parent through some out-of-band method 89 to complete the chain of trust. Depending on the desires of the 90 parent, the child might send their DNSKEY record, a DS record, or 91 both. 93 Each time the child changes the key that is represented in the 94 parent, the updated and/or deleted key information has to be 95 communicated to the parent and published in the parent's zone. How 96 this information is sent to the parent depends on the relationship 97 the child has with the parent. In many cases this is a manual 98 process, and not an easy one. For each key change, there may be up 99 to two interactions with the parent. Any manual process is 100 susceptible to mistakes and/or errors. In addition, due to the 101 annoyance factor of the process, operators may avoid changing keys or 102 skip needed steps to publish the new DS at the parent. 104 DNSSEC provides data integrity to information published in DNS; thus 105 DNS publication can be used to automate maintenance of delegation 106 information. This document describes a method to automate 107 publication of subsequent DS records, after the initial one has been 108 published. 110 Readers are expected to be familiar with DNSSEC, including [RFC4033], 111 [RFC4034], [RFC4035], [RFC5011] and [RFC6781]. 113 This document is a compilation of two earlier drafts: draft-barwood- 114 dnsop-ds-publish[I-D.ds-publish] and draft-wkumari-dnsop-ezkeyroll. 116 This document outlines a technique in which the parent periodically 117 (or upon request) polls its signed children and automatically publish 118 new DS records. To a large extent, the procedures this document 119 follows are as described in [RFC6781] section 4.1.2. 121 This technique is designed to be friendly both to fully automated 122 tools and humans. Fully automated tools can perform all the actions 123 needed without human intervention, and thus can monitor when it is 124 safe to move to the next step. 126 The solution described in this document only allows transferring 127 information about DNSSEC keys (DS and DNSKEY) from the child to the 128 parental agent. It lists exactly what the parent should publish, and 129 allows for publication of stand-by keys. A different protocol, 130 [I-D.csync], can be used to maintain other important delegation 131 information, such as NS and glue. These two protocols have been kept 132 as separate solutions because the problems are fundamentally 133 different, and a combined solution is overly complex. 135 This document describes a method for automating maintenance of the 136 delegation trust information, and proposes a polled / periodic 137 trigger for simplicity. Some users may prefer a different trigger, 138 for example a button on a webpage, a REST interface or a DNS NOTIFY. 139 These alternate / additional triggers are not discussed in this 140 document. 142 This proposal does not include all operations needed for the 143 maintenance of DNSSEC key material, specifically the initial 144 introduction or complete removal of all keys. Because of this, 145 alternate communications mechanisms must always exist, potentially 146 introducing more complexity. 148 1.1. Terminology 150 The terminology we use is defined in this section. 152 Highlighted roles: 154 o Child: "The entity on record that has the delegation of the domain 155 from the parent" 157 o Parent: "The domain in which the child is registered" 159 o Child DNS Operator: "The entity that maintains and publishes the 160 zone information for the child DNS" 162 o Parental Agent: "The entity that the child has relationship with, 163 to change its delegation information" 165 o Provisioning system: "A system that the operator of the master DNS 166 server operates to maintain the information published in the DNS. 167 This includes the systems that sign the DNS data" 169 RRR is our shorthand for Registry/Registrar/Registrant model of 170 parent child relationship see Appendix A for more. 172 1.2. Requirements Notation 174 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 175 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 176 document are to be interpreted as described in [RFC2119]. 178 2. Background 180 2.1. DNS Delegations 182 DNS operation consists of delegations of authority. For each 183 delegation there are (most of the time) two parties: the parent and 184 the child. 186 The parent publishes information about the delegations to the child; 187 for the name servers it publishes an NS [RFC1035] RRset that lists a 188 hint for name servers that are authoritative for the child. The 189 child also publishes a NS RRset, and this set is the authoritative 190 list of name servers to the child zone. 192 The second RRset the parent sometimes publishes is the DS [RFC4034] 193 set. The DS RRset provides information about the DNSKEY(s) that the 194 child has told the parent it will use to sign its DNSKEY RRset. In 195 DNSSEC trust relationship between zones is provided by the following 196 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, it failed to reach consensus. There is 205 also a similar proposal in [I-D.parent-zones]. 207 As the DS record can only be present at the parent ( [RFC4034]), some 208 other method is needed to automate which DNSKEYs are picked to be 209 represented in the parent zone's DS records. One possibility is to 210 use flags in the DNSKEY record. If the SEP bit is set, this 211 indicates that the DNSKEY is intended for use as a secure entry 212 point. This DNSKEY signs the DNSKEY RRset, and the Parental Agent 213 can calculate DS records based on that. But this fails to meet some 214 operating needs, including the child having no influence what DS 215 digest algorithms are used and DS records can only be published for 216 keys that are in the DNSKEY RRset, and thus this technique would not 217 be compatible with Double-DS ( [RFC6781] ) key rollover. 219 2.2. Relationship Between Parent and Child DNS Operator 221 In practical application, there are many different relationships 222 between the parent and Child DNS Operators. The type of relationship 223 affects how the Child DNS Operator communicates with the parent. 224 This section will highlight some of the different situations, but is 225 by no means a complete list. 227 Different communication paths: 229 o Direct/API: The child can change the delegation information via 230 automated/scripted means. EPP[RFC5730], used by many TLDs is an 231 example of this. Another example is the web service's 232 programmatic interfaces that Registrars make available to their 233 Resellers. 235 o User Interface: The Child uses a (web) site set up by the Parental 236 Agent for updating delegation information. 238 o Indirect: The communication has to be transmitted via out-of-band 239 between two parties, such as by email or telephone. This is 240 common when the Child's DNS operator is neither the child itself 241 nor the Registrar for the domain but a third party. 243 o Multi-step Combinations: The information flows through an 244 intermediary. It is possible, but unlikely, that all the steps 245 are automated via API's and there are no humans are involved. 247 A domain name holder (Child) may operate its own DNS servers or 248 outsource the operation. While we use the word parent as a singular, 249 parent can consist of single entity or a composite of many discrete 250 parts that have rules and roles. We refer to the entity that the 251 child corresponds with as the Parent. 253 An organization (such as an enterprise) may delegate parts of its 254 name-space to be operated by a group that is not the same as that 255 which operates the organization's DNS servers. In some of these 256 cases the flow of information is handled in either an ad hoc manner 257 or via some corporate mechanism; this can range from email to fully- 258 automated operation. 260 2.2.1. Solution Space 262 This document is aimed at the cases in which there is a separation 263 between the child and parent. 265 A further complication is when the Child DNS Operator 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; the 273 Parental Agent can inject any delegation changes directly into the 274 Parent's Provisioning system. The techniques described below are not 275 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 DNS Operator access 279 to its delegation/registration account. 281 Some parents want the child to express their DNSKEYS in the form of 282 DS records, while others want to receive the 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. This solution is 285 DS vs DNSKEY agnostic, and allows operation with either. 287 2.2.2. DNSSEC key change process 289 After a Child DNS Operator first signs the zone, there is a need to 290 interact with the Parent, for example via a delegation account 291 interface, to "upload / paste-in the zone's DS information". This 292 action of logging in through the delegation account user interface 293 authenticates that the user is authorized to change delegation 294 information for the child published in the parent zone. In the case 295 where the Child DNS Operator does not have access to the registration 296 account, the Child needs to perform the action. 298 At a later date, the Child DNS Operator may want to publish a new DS 299 record in the parent, either because they are changing keys, or 300 because they want to publish a stand-by key. This involves 301 performing the same process as before. Furthermore when this is a 302 manual process with cut and paste, operational mistakes will happen 303 -- or worse, the update action is not performed at all. 305 The Child DNS Operator may also introduce new keys, and can do so 306 when old keys exist and can be used. The Child may also remove old 307 keys, but this document does not support removing all keys. This is 308 to avoid making signed zones unsigned. The Child may not enroll the 309 initial key or introduce a new key when there are no old keys that 310 can be used (without some additional, out of band, validation of the 311 keys), because there is no way to validate the information. 313 3. CDS / CDNSKEY (Child DS/ Child DNSKEY) Record Definitions 315 This document specifies two new DNS resource records, CDS and 316 CDNSKEY. These records are used to convey, from one zone to its 317 parent, the desired contents of the zone's DS resource record set 318 residing in the parent zone. 320 The CDS / CDNSKEY resource records are published in the child zone 321 and gives the child control of what is published for it in the 322 parental zone. The CDS / CDNSKEY RRset expresses what the child 323 would like the DS RRset to look like after the change; it is a 324 "replace" operation, and it is up to the consumer of the records to 325 translate that into the appropriate add/delete operations in the 326 provisioning systems (and in the case of CDNSKEY, to generate the DS 327 from the DNSKEY). If no CDS / CDNSKEY RRset is present in child, 328 this means that no change is needed. 330 [[RFC Editor: Please remove this paragraph before publication] 331 Version -04 of the ID that became this working group document (http:/ 332 /tools.ietf.org/id/draft-kumari-ogud-dnsop-cds-04.txt) defined a new 333 record (CTA) that could hold either a DS or a DNSKEY record (with a 334 selector to differentiate between them). In a shocking development, 335 there was almost full consensus that this was horrid :-) ] 337 3.1. CDS Resource Record Format 339 The wire and presentation format of the CDS ("Child DS") resource 340 record is identical to the DS record [RFC4034]. IANA has allocated 341 RR code 59 for the CDS resource record via expert review 342 [I-D.ds-publish]. The CDS RR uses the same registries as DS for its 343 fields. 345 No special processing is performed by authoritative servers or by 346 revolvers, when serving or resolving. For all practical purposes CDS 347 is a regular RR type. 349 3.2. CDNSKEY Resource Record Format 351 The wire and presentation format of the CDNSKEY ("Child DNSKEY") 352 resource record is identical to the DNSKEY record. IANA has 353 allocated RR code TBA1 for the CDNSKEY resource record via expert 354 review. The CDNSKEY RR uses the same registries as DNSKEY for its 355 fields. 357 No special processing is performed by authoritative servers or by 358 revolvers, when serving or resolving. For all practical purposes 359 CDNSKEY is a regular RR type. 361 4. Automating DS Maintainance With CDS/CDNSKEY records 363 CDS/CDNSKEY resource records are intended to be "consumed" by 364 delegation trust maintainers. The use of CDS/CDNSKEY is optional. 366 The child SHOULD publish both CDS and CDNSKEY resource records. If 367 the child knows which the parent consumes, it MAY choose to only 368 publish that record type (for example, some children wish the parent 369 to publish a DS, but they wish to keep the DNSKEY "hidden" until 370 needed). If the child publishes both, the two RRsets MUST match in 371 content. 373 4.1. CDS / CDNSKEY Processing Rules 375 If there are no CDS / CDNSKEY RRset in the child, this signals that 376 no change should be made to the current DS set. This means that, 377 once the child and parent are in sync, the Child DNS Operator MAY 378 remove all CDS and CDNSKEY resource records from the zone The Child 379 DNS Operator may choose to do this to decrease the size of the zone, 380 or to decrease the workload for the parent (if the parent receives no 381 CDS / CDNSKEY records it can go back to sleep. If it does receive a 382 CDS or CDNSKEY RRset it needs to check them against what is currently 383 published - see Section 5) 385 Following acceptance rules are placed on the CDS / CDNSKEY resource 386 records as follows: 388 o Location: "the CDS / CDNSKEY resource records MUST be at the child 389 zone apex". 391 o Signer: "MUST be signed with a key that is represented in both the 392 current DNSKEY and DS RRset's" (unless the parent uses the CDS / 393 CDNSKEY RRset for initial enrollment, in that case the parent 394 validates the CDS / CDNSKEY though some other means (see 395 Section 6.1 and the Security Considerations.)) 397 o Continuity: "MUST NOT break the current delegation if applied to 398 DS RRset" 400 If any these conditions fail the CDS / CDNSKEY resource record MUST 401 be ignored. 403 5. CDS / CDNSKEY Publication 405 Child DNS Operator publishes CDS and / or CDNSKEY resource records. 406 In order to be valid, the CDS / CDNSKEY RRset MUST be compliant with 407 the rules in Section 4.1. When the Parent DS is "in-sync" with the 408 CDS / CDNSKEY resource records, the Child DNS Operator MAY delete the 409 CDS / CDNSKEY record(s); the child can determine if this is the case 410 by querying for DS records in the parent. 412 6. Parent Side CDS / CDNSKEY Consumption 414 The CDS / CDNSKEY RRset SHOULD be used by the Parental Agent to 415 update the DS RRset in the parent zone. The Parental Agent for this 416 uses a tool that understands the CDS / CDNSKEY signing rules from 417 Section 4.1 so it might not be able to use a standard validator. 419 The parent MUST choose to use either CDNSKEY or CDS resource records 420 as their default updating mechanism. The parent MAY only accept 421 either CDNSKEY or CDS, but it MAY also accept both, so it can use the 422 other in the absence of the default updating mechanism, but it MUST 423 NOT expect there to be both. 425 6.1. Detecting a Changed CDS / CDNSKEY 427 How the Parental Agent gets the CDS / CDNSKEY RRset may differ, below 428 are two examples as how this can take place. 430 Polling The Parental Agent operates a tool that periodically checks 431 each of the children that has a DS record to see if there is a 432 CDS or CDNSKEY RRset. 434 Pushing The delegation user interface has a button {Fetch DS} when 435 pushed preforms the CDS / CDNSKEY processing. If the Parent 436 zone does not contain DS for this delegation then the "push" 437 SHOULD be ignored. If the Parental Agent displays the contents 438 of the CDS / CDSNKEY to the user and gets confirmation that 439 this represents their key, the Parental Agent MAY use this for 440 initial enrolment (when the Parent zone does not contain the DS 441 for this delegation). 443 In either case the Parental Agent MAY apply additional rules that 444 defer the acceptance of a CDS / CDNSKEY change, these rules may 445 include a condition that the CDS / CDNSKEY remains in place and valid 446 for some time period before it is accepted. It may be appropriate in 447 the "Pushing" case to assume that the Child is ready and thus accept 448 changes without delay. 450 6.1.1. CDS / CDNSKEY Polling 452 This is the only defined use of CDS / CDNSKEY resource records in 453 this document. There are limits to the scaleability of polling 454 techniques, thus some other mechanism is likely to be specified later 455 that addresses CDS / CDNSKEY resource record usage in the situation 456 where polling does not scale to. Having said that Polling will work 457 in many important cases such as enterprises, universities and smaller 458 TLDs. In many regulatory environments the registry is prohibited 459 from talking to the registrant. In most of these cases the 460 registrant has a business relationship with the registrar, and so the 461 registrar can offer this as a service. 463 If the CDS / CDNSKEY RRset does not exist, the Parental Agent MUST 464 take no action. Specifically it MUST NOT delete or alter the 465 existing DS RRset. 467 6.1.2. Other Mechanisms 469 It is assumed that other mechanisms will be implemented to trigger 470 the parent to look for an updated CDS / CDNSKEY RRsets. As the CDS / 471 CDNSKEY resource records are validated with DNSSEC, these mechanisms 472 can be unauthenticated (for example, a child could telephone its 473 parent and request that they process the new CDS or CDNSKEY resource 474 records or an unauthenticated POST could be made to a webserver (with 475 rate-limiting).) 477 Other documents can specify the trigger conditions. 479 6.2. Using the New CDS / CDNSKEY Records 481 Regardless of how the Parental Agent detected changes to a CDS / 482 CDNSKEY RRset, the Parental Agent SHOULD use a DNSSEC validator to 483 obtain a validated CDS / CDNSKEY RRset from the Child zone. The only 484 exception to this is if the parent performs some additional 485 validation on the data to confirm that it is the "correct" key. This 486 behavior is NOT RECOMMENDED. 488 The Parental Agent MUST ensure that previous versions of the CDS / 489 CDNSKEY RRset do not overwrite more recent versions. This MAY be 490 accomplished by checking that the signature inception in the RRSIG 491 for CDS / CDNSKEY RRset is later and/or the serial number on the 492 child's SOA is greater. This may require the Parental Agent to 493 maintain some state information. 495 The Parental Agent MAY take extra security measures. For example, to 496 mitigate the possibility that a Child's key signing key has been 497 compromised, the Parental Agent may, for example, inform (by email or 498 other methods ) the Child DNS Operator of the change. However the 499 precise out-of-band measures that a parent zone SHOULD take are 500 outside the scope of this document. 502 Once the Parental Agent has obtained a valid CDS / CDNSKEY RRset it 503 MUST check the publication rules from section 4.1. In particular the 504 Parental Agent MUST check the Continuity rule and do its best not to 505 invalidate the Child zone. Once checked and if the information in 506 the CDS / CDNSKEY and DS differ it may apply the changes to the 507 parent zone. If the parent consumes CDNSKEY, the parent should 508 calculate the DS before doing this comparison. 510 6.2.1. Parent Calculates DS 512 There are cases where the Parent wants to calculate the DS record due 513 to policy reasons. In this case, the Child publishes CDNSKEY records 514 and the parent calculates the DS records on behalf of the children. 516 When a Parent operates in "calculate DS" mode it can operate in one 517 of two sub-modes 519 full it only publishes DS records it calculates from DNSKEY records, 521 augment it will make sure there are DS records for the digest 522 algorithm(s) it requires(s). 524 In the case where the parent fetches the CDNSKEY RRset and calculate 525 the DS it MAY be the case that the DS published in the parent zone is 526 not identical with the data in the CDS resource record made available 527 by the child. 529 7. IANA Considerations 531 IANA has assigned RR Type code 59 for the CDS resource record. This 532 was done for an earlier version of this document[I-D.ds-publish] This 533 document is to become the reference for CDS RRtype. 535 IANA is requested to assign another RR Type for the CDNSKEY, and to 536 replace TBA1 with this value (currently 60 is still free, it would be 537 nice if that were assigned...) 539 8. Privacy Considerations 541 All of the information handled / transmitted by this protocol is 542 public information published in the DNS. 544 9. Security Considerations 546 This work is for the normal case; when things go wrong there is only 547 so much that automation can fix. 549 If child breaks DNSSEC validation by removing all the DNSKEYs that 550 are represented in the DS set its only repair actions are to contact 551 the parent or restore the DNSKEYs in the DS set. 553 In the event of a compromise of the server or system generating 554 signatures for a zone, an attacker might be able to generate and 555 publish new CDS resource records. The modified CDS recourse records 556 will be picked up by this technique and so may allow the attacker to 557 extend the effective time of his attack. If there a delay in 558 accepting changes to DS, as in [RFC5011], then the attacker needs to 559 hope his activity is not detected before the DS in parent is changed. 560 If this type of change takes place, the child needs to contact the 561 parent (possibly via a registrar web interface) and remove any 562 compromised DS keys. 564 A compromise of the account with the parent (e.g. registrar) will not 565 be mitigated by this technique, as the "new registrant" can delete/ 566 modify the DS records at will. 568 While it may be tempting, this SHOULD NOT be used for initial 569 enrollment of keys since there is no way to ensure that the initial 570 key is the correct one. If is used, strict rules for inclusion of 571 keys such as hold down times, challenge data inclusion or similar, 572 ought to be used, along with some kind of challenge mechanism. A 573 child cannot use this mechanism to go from signed to unsigned 574 (publishing an empty CDS / CDNSKEY RRset means no-change should be 575 made in the parent). 577 The CDS RR type should allow for enhanced security by simplifying 578 process. Since key change is automated, updating a DS RRset by other 579 means may be regarded as unusual and subject to extra security 580 checks. 582 As this introduces a new mechanism to update information in the 583 parent it MUST be clear who is fetching the records and creating the 584 appropriate records in the parent zone. Specifically some operations 585 may use other mechanisms than what is described here. For example, a 586 registrar may assume that it is maintaining the DNSSEC key 587 information in the registry, and may have this cached. If the 588 registry is fetching the CDS / CDNSKEY RRset then the registry and 589 registrar may have different views of the DNSSEC key material and the 590 result of such a situation is unclear. Therefore, this mechanism 591 SHOULD NOT be use to bypass intermediaries that might cache 592 information and because of that get the wrong state. 594 If there is a failure in applying changes in child zone to all DNS 595 servers listed in either parent or child NS set it is possible that 596 the Parental agent may get confused, either because it gets different 597 answers on different checks or CDS RR validation fails. In the worst 598 case, the Parental Agent performs an action reversing a prior action 599 but after the child signing system decides to take the next step in 600 the key change process, resulting in a broken delegation. 602 DNS is a loosely coherent distributed database with local caching; 603 therefore, it is important to allow old information to expire from 604 caches before deleting DS or DNSKEY records. Similarly, it is 605 important to allow new records to propagate through the DNS before 606 use, see [RFC6781] and [I-D.key-time] 608 It is common practice for users to outsource their DNS hosting to a 609 3rd party DNS provider. In order for that provider to be able to 610 maintain the DNSSEC information some users give the provider their 611 registrar login credentials (which obviously has negative security 612 implications). Deploying the solution described in this document 613 allows the 3rd party DNS provider to maintain the DNSSEC information 614 without giving them the registrar credentials, thereby improving 615 security. 617 By automating the maintenance of the DNSSEC key information (and 618 removing humans from the process), we expect to decrease the number 619 of DNSSEC related outages, which should increase DNSSEC deployment. 621 10. Acknowledgements 623 We would like to thank a large number of folk, including: Mark 624 Andrews, Joe Abley, Jaap Akkerhuis, Roy Arends, Doug Barton, Brian 625 Dickson, Paul Ebersman, Tony Finch, Jim Galvin, Paul Hoffman, Samir 626 Hussain, Tatuya Jinmei, Olaf Kolkman, Stephan Lagerholm, Cricket Liu, 627 Matt Larson, Marco Sanz, Antoin Verschuren, Suzanne Woolf, Paul 628 Wouters, John Dickinson, Timothe Litt and Edward Lewis. 630 Special thanks to Wes Hardaker for contributing significant text and 631 creating the complementary (CSYNC) solution, and to Patrik Faltstrom, 632 Paul Hoffman, Matthijs Mekking and Mukund Sivaraman for text and in- 633 depth review. 635 There were a number of other folk with whom we discussed this, 636 apologies for not remembering everyone. 638 11. References 640 11.1. Normative References 642 [RFC1035] Mockapetris, P., "Domain names - implementation and 643 specification", STD 13, RFC 1035, November 1987. 645 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 646 Requirement Levels", BCP 14, RFC 2119, March 1997. 648 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 649 Rose, "DNS Security Introduction and Requirements", RFC 650 4033, March 2005. 652 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 653 Rose, "Resource Records for the DNS Security Extensions", 654 RFC 4034, March 2005. 656 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 657 Rose, "Protocol Modifications for the DNS Security 658 Extensions", RFC 4035, March 2005. 660 [RFC5011] StJohns, M., "Automated Updates of DNS Security (DNSSEC) 661 Trust Anchors", STD 74, RFC 5011, September 2007. 663 [RFC6781] Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC 664 Operational Practices, Version 2", RFC 6781, December 665 2012. 667 11.2. Informative References 669 [I-D.auto-cpsync] 670 Mekking, W., "Automated (DNSSEC) Child Parent 671 Synchronization using DNS UPDATE", draft-mekking-dnsop- 672 auto-cpsync-01 (work in progress), December 2010. 674 [I-D.csync] 675 Hardaker, W., "Child To Parent Synchronization in DNS", 676 draft-hardaker-dnsop-csync-02 (work in progress), July 677 2013. 679 [I-D.ds-publish] 680 Barwood, G., "DNS Transport", draft-barwood-dnsop-ds- 681 publish-02 (work in progress), June 2011. 683 [I-D.key-time] 684 Mekking, W., "DNSSEC Key Timing Considerations", draft- 685 ietf-dnsop-dnssec-key-timing-03 (work in progress), July 686 2012. 688 [I-D.parent-zones] 689 Andrews, M., "Updating Parent Zones", draft-andrews-dnsop- 690 update-parent-zones-04 (work in progress), November 2013. 692 [RFC5730] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)", 693 STD 69, RFC 5730, August 2009. 695 [RFC5910] Gould, J. and S. Hollenbeck, "Domain Name System (DNS) 696 Security Extensions Mapping for the Extensible 697 Provisioning Protocol (EPP)", RFC 5910, May 2010. 699 Appendix A. RRR background 701 In the RRR world, the different parties are frequently from different 702 organizations. In the single enterprise world there are also 703 organizational/geographical/cultural separations that affect how 704 information flows from a Child to the parent. 706 Due to the complexity of the different roles and interconnections, 707 automation of delegation information Expolhas not yet occurred. 708 There have been proposals to automate this, in order to improve the 709 reliability of the DNS. These proposals have not gained enough 710 traction to become standards. 712 For example in many of the TLD cases there is the RRR model 713 (Registry, Registrar and Registrant). The Registry operates DNS for 714 the TLD, the Registrars accept registrations and place information 715 into the Registries database. The Registrant only communicates with 716 the Registrar; frequently the Registry is not allowed to communicate 717 with the Registrant. In that case as far as the registrant is 718 concerned the Registrar == Parent. 720 In many RRR cases the Registrar and Registry communicate via 721 EPP[RFC5730] and use the EPP DNSSEC extension [RFC5910]. In a number 722 of ccTLDs there are other mechanisms in use as well as EPP, but in 723 general there seems to be a movement towards EPP usage when DNSSEC is 724 enabled in the TLD. 726 Appendix B. Changes / Author Notes. 728 [RFC Editor: Please remove this section before publication ] 730 WG-10 to WG-11 732 o More useful text from Matthijs. 734 o Explained why the child might want to remove the CDS / CDNSKEY 735 Records. 737 WG-09 to WG-10 739 o Incorporated off list comments from Stephan Lagerholm. Largest 740 change is fixing discrepancy between parent MAY perform OOB 741 validation and the Signer rule in 4.1. Clarified by updating 742 signer rule to allow 744 WG-08 to WG-09 746 o New text from Paul Hoffman for the first paragraph of the intro. 748 o ... with a modification from Jaap. 750 WG-07 to WG-08 752 o Incorporated text from Antoin Verschuren at the end of Section 6. 754 o Comments from Paul Hoffman and Tim W 756 WG-06 to WG-07 758 o Incorporated nits / editorial comments from Tim Wicinski. 760 o 761 * Reference for Mark's draft was incorrect, Wes Hardaker doesn't 762 work for ISC :-P 764 * Normalized CDS record / CDS resource record / records / etc. 766 * Language cleanup / nits / poor grammar. 768 * removed "punted" colloquialism. 770 WG-05 to WG-06 772 o Consensus (according to me!) was that mail thread said "Child MAY 773 remove the CDS record". Changed to accomodate. 775 o "The proposal below can operate with both models, but the child 776 needs to be aware of the parental policies." - removed "but the 777 child needs to be aware of the parental policies.". This is no 778 longer true, as we suggest publishing both CDS and CDSNKEY. 780 o Added: "without some additional out of band process" to "The Child 781 may not enroll the initial key or introduce a new key when there 782 are no old keys that can be used (without some additional, out of 783 band, validation of the keys), because there is no way to validate 784 the information." 786 o Added a bit to the IANA section, requesting that TBA1 be replaced 787 with the IANA allocated code. 789 o Removed" Some parents prefer to accept DNSSEC key information in 790 DS format, some parents prefer to accept it in DNSKEY format, and 791 calculate the DS record on the child's behalf. Each method has 792 pros and cons, both technical and policy. This solution is DS vs 793 DNSKEY agnostic, and allows operation with either." from Section 4 794 as it is covered in Section 2.2.1 796 o Remove a bunch of comments from the XML. I was getting tired of 797 scrolling past them. If the authors need them back, they are in 798 SVN commit 47. 800 WG-04 to WG-05 802 o More comments from Patrik, Paul and Ed. 804 o Many nits and fixes from Matthijs Mekking. 806 o Outstanding question: Should we remove the "Child SHOULD remove 807 the CDS record" text? Mail sent to list. 809 WG-03 to WG-04 811 o Large number of comments and changes from Patrik. 813 WG-02 to WG-03 815 o Fixed some references to RFC 5011 - from Samir Hussain. 817 o Fixed some spelling / typos - from Samir Hussain. 819 o A number of clarifiations on the meaning on an empty / non- 820 existant CDS RRset - thanks to JINMEI, Tatuya 822 o Be consistent in mentioning both CDS and CDNSKEY throughout the 823 document. 825 WG-01 to WG-02 827 o Many nits and suggestions from Mukund. 829 o Matthijs: " I still think that it is too strong that the Child DNS 830 Operator SHOULD/MUST delete the CDS RRset when the Parent DS is 831 "in-sync". This should be a MAY" 833 WG-00 to WG-01 835 o Addressed Vancouver: "Paul Hoffmann: NOT ready for WGLC. None of 836 the 2 documents explain why there is a split between the two 837 strategies." Thanks to Paul for providing text. 839 From -05 to WG-00: 841 o Nothing rchanged, resubmit under new name. 843 From 04 to 05 845 o Renamed the record back to CDS. 847 From 03 to 04. 849 o Added text explaining that CDS and CSYNC complement each other, 850 not replace or compete. 852 o Changed format of record to be to allow the 853 publication of DS **or** DNSKEY. 855 o Bunch of text changed to cover the above. 857 o Added a bit more text on the polling scaling stuff, expectation 858 that other triggers will be documented. 860 From 02 to 03 862 o Applied comments by Matthijs Mekking 864 o Incorporated suggestions from Edward Lewis about structure 866 o Reworked structure to be easier for implementors to follow 868 o Applied many suggestions from a wonderful thorough review by John 869 Dickinson 871 o Removed the going Unsigned option 873 From 01 to 02 875 o Major restructuring to facilitate easier discussion 877 o Lots of comments from DNSOP mailing list incorporated, including 878 making draft DNSKEY/DS neutral, explain different relationships 879 that exists, 881 o added more people to acks. 883 o added description of enterprise situations 885 o Unified on using Parental Agent over Parental Representative 887 o Removed redundant text when possible 889 o Added text to explain what can go wrong if not all child DNS 890 servers are in sync. 892 o Reference prior work by Matthijs Mekking 894 o Added text when parent calculates DS from DNSKEY 896 From - to -1. 898 o Removed from section .1: "If a child zone has gone unsigned, i.e. 899 no DNSKEY and no RRSIG in the zone, the parental representative 900 MAY treat that as intent to go unsigned. (NEEDS DISCUSSION)." 901 Added new text at end. -- suggestion by Scott Rose 20/Feb/13. 903 o Added some background on the different DNS Delegation operating 904 situations and how they affect interaction of parties. This moved 905 some blocks of text from later sections into here. 907 o Number of textual improvements from Stephan Lagerholm 909 o Added motivation why CDS is needed in CDS definition section 911 o Unified terminology in the document. 913 o Much more background 915 Authors' Addresses 917 Warren Kumari 918 Google 919 1600 Amphitheatre Parkway 920 Mountain View, CA 94043 921 US 923 Email: warren@kumari.net 925 Olafur Gudmundsson 926 Shinkuro Inc. 927 4922 Fairmont Av, Suite 250 928 Bethesda, MD 20814 929 USA 931 Email: ogud@ogud.com 933 George Barwood 934 33 Sandpiper Close 935 Gloucester GL2 4LZ 936 United Kingdom 938 Email: george.barwood@blueyonder.co.uk