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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Line 518 has weird spacing: '... full it on...' == Line 520 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 14, 2014) is 2959 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for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: draft-ietf-dnsop-dnssec-key-timing has been published as RFC 7583 Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--).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 16, 2014 Shinkuro Inc. 6 G. Barwood 8 April 14, 2014 10 Automating DNSSEC Delegation Trust Maintenance 11 draft-ietf-dnsop-delegation-trust-maintainance-07 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 16, 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 . . . . . . . . . . . 11 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 . . . . . . . . . . . . . . . . . . . . . . . 19 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 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 roll, there may be up to 99 two interactions with the parent. Any manual process is susceptible 100 to mistakes and/or errors. In addition, due to the annoyance factor 101 of the process, operators may avoid performing key rollovers or skip 102 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 maintanance of the 136 delegation trust information, and proposes a polled / periodic 137 trigger for simplicity. Some users may prefer a different trigger, 138 such as a button on a webpage, a REST interface, DNS NOTIFY, etc. 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 Parent DNS Operator: "The entity that maintains and publishes the 163 zone information for the parent DNS" 165 o Parental Agent: "The entity that the child has relationship with, 166 to change its delegation information" 168 o Provisioning system: "A system that the operator of the master DNS 169 server operates to maintain the information published in the DNS. 170 This includes the systems that sign the DNS data" 172 RRR is our shorthand for Registry/Registrar/Registrant model of 173 parent child relationship see Appendix A for more. 175 1.2. Requirements Notation 177 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 178 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 179 document are to be interpreted as described in [RFC2119]. 181 2. Background 183 2.1. DNS Delegations 185 DNS operation consists of delegations of authority. For each 186 delegation there are (most of the time) two parties: the parent and 187 the child. 189 The parent publishes information about the delegations to the child; 190 for the name servers it publishes an NS [RFC1035] RRset that lists a 191 hint for name servers that are authoritative for the child. The 192 child also publishes a NS RRset, and this set is the authoritative 193 list of name servers to the child zone. 195 The second RRset the parent sometimes publishes is the DS [RFC4034] 196 set. The DS RRset provides information about the DNSKEY(s) that the 197 child has told the parent it will use to sign its DNSKEY RRset. In 198 DNSSEC trust relationship between zones is provided by the following 199 chain: 201 parent DNSKEY --> DS --> child DNSKEY. 203 A prior proposal [I-D.auto-cpsync] suggested that the child send an 204 "update" to the parent via a mechanism similar to Dynamic Update. 205 The main issue became: How does the child find the actual parental 206 agent/server to send the update to? While that could have been 207 solved via technical means, it failed to each consensus. There is 208 also a similar proposal in [I-D.parent-zones]. 210 As the DS record can only be present at the parent ( [RFC4034]), some 211 other method is needed to automate which DNSKEYs are picked to be 212 represented in the parent zone's DS records. One possibility is to 213 use flags in the DNSKEY record. If the SEP bit is set, this 214 indicates that the DNSKEY is intended for use as a secure entry 215 point. This DNSKEY signs the DNSKEY RRset, and the Parental Agent 216 can calculate DS records based on that. But this fails to meet some 217 operating needs, including the child having no influence what DS 218 digest algorithms are used and DS records can only be published for 219 keys that are in the DNSKEY RRset, and thus this technique would not 220 be compatible with Double-DS key rollover. 222 2.2. Relationship Between Parent and Child DNS Operator 224 In practical application, there are many different relationships 225 between the parent and child DNS operators. The type of relationship 226 affects how the Child DNS Operator communicates with the parent. 227 This section will highlight some of the different situations, but is 228 by no means a complete list. 230 Different communication paths: 232 o Direct/API: The child can change the delegation information via 233 automated/scripted means. EPP[RFC5730], used by many TLDs is an 234 example of this. Another example is the web service's 235 programmatic interfaces that Registrars make available to their 236 Resellers. 238 o User Interface: The Child uses a (web) site set up by the Parental 239 Agent for updating delegation information. 241 o Indirect: The communication has to be transmitted via out-of-band 242 between two parties, such as email, telephone etc.. This is common 243 when the Child's DNS operator is neither the child itself nor the 244 Registrar for the domain but a third party. 246 o Multi-step Combinations: The information flows through an 247 intermediary. It is possible, but unlikely, that all the steps 248 are automated via API's and there are no humans are involved. 250 A domain name holder (Child) may operate its own DNS servers or 251 outsource the operation. While we use the word parent as a singular, 252 parent can consist of single entity or a composite of many discrete 253 parts that have rules and roles. We refer to the entity that the 254 child corresponds with as the Parent. 256 IIn another common case an organization may delegate parts of its 257 name-space to be operated by a group that is not the same as that 258 which operates the organization's DNS servers. In this case the flow 259 of information is frequently handled in either an ad hoc manner or 260 via some corporate mechanism; this can range from email to fully- 261 automated operation. 263 2.2.1. Solution Space 265 This document is aimed at the cases in which there is a separation 266 between the child and parent. 268 A further complication is when the Child DNS Operator is not the 269 Child. There are two common cases of this: 271 a) The Parental Agent (e.g. registrar) handles the DNS operation. 273 b) A third party takes care of the DNS operation. 275 If the Parental Agent is the DNS operator, life is much easier; the 276 Parental Agent can inject any delegation changes directly into the 277 Parent's Provisioning system. The techniques described below are not 278 needed in the case when Parental Agent is the DNS operator. 280 In the case of a third party DNS operator, the Child either needs to 281 relay changes in DNS delegation or give the Child DNS Operator access 282 to its delegation/registration account. 284 Some parents want the child to express their DNSKEYS in the form of 285 DS records, while others want to receive the DNSKEY records and 286 calculate the DS records themselves. There is no consensus on which 287 method is better; both have good reasons to exist. This solution is 288 DS vs DNSKEY agnostic, and allows operation with either. 290 2.2.2. DNSSEC key change process 292 After a Child DNS Operator first signs the zone, there is a need to 293 interact with the Parent, for example via a delegation account 294 interface, to "upload / paste-in the zone's DS information". This 295 action of logging in through the delegation account user interface 296 authenticates that the user is authorized to change delegation 297 information for the child published in the parent zone. In the case 298 where the "Child DNS Operator" does not have access to the 299 registration account, the Child needs to perform the action. 301 At a later date, the Child DNS Operator may want to publish a new DS 302 record in the parent, either because they are rolling keys, or 303 because they want to publish a stand-by key. This involves 304 performing the same process as before. Furthermore when this is a 305 manual process with cut and paste, operational mistakes will happen 306 -- or worse, the update action is not performed at all. 308 The Child DNS Operator may also introduce new keys, and can do so 309 when old keys exist and can be used. The Child may also remove old 310 keys, but this document does not support removing all keys. This is 311 to avoid making signed zones unsigned. The Child may not enroll the 312 initial key or introduce a new key when there are no old keys that 313 can be used (without some additional, out of band, validation of the 314 keys), because there is no way to validate the information. 316 3. CDS / CDNSKEY (Child DS/ Child DNSKEY) Record Definitions 318 This document specifies two new DNS resource records, CDS and 319 CDNSKEY. These records are used to convey, from one zone to its 320 parent, the desired contents of the zone's DS resource record set 321 residing in the parent zone. 323 The CDS / CDNSKEY resource records are published in the child zone 324 and gives the child control of what is published for it in the 325 parental zone. The CDS / CDNSKEY RRset expresses what the child 326 would like the DS RRset to look like after the change; it is a 327 "replace" operation, and it is up to the consumer of the records to 328 translate that into the appropriate add/delete operations in the 329 registration systems (and in the case of CDNSKEY, to generate the DS 330 from the DNSKEY). If no CDS / CDNSKEY RRset is present in child, 331 this means that no change is needed. 333 [[RFC Editor: Please remove this paragraph before publication] 334 Version -04 of the ID that became this working group document (http:/ 335 /tools.ietf.org/id/draft-kumari-ogud-dnsop-cds-04.txt) defined a new 336 record (CTA) that could hold either a DS or a DNSKEY record (with a 337 selector to differentiate between them). In a shocking development, 338 there was almost full consensus that this was horrid :-) ] 340 3.1. CDS Resource Record Format 342 The wire and presentation format of the CDS ("Child DS") resource 343 record is identical to the DS record [RFC4034]. IANA has allocated 344 RR code 59 for the CDS resource record via expert review 345 [I-D.ds-publish]. The CDS RR uses the same registries as DS for its 346 fields. 348 No special processing is performed by authoritative servers or by 349 revolvers, when serving or resolving. For all practical purposes CDS 350 is a regular RR type. 352 3.2. CDNSKEY Resource Record Format 354 The wire and presentation format of the CDNSKEY ("Child DNSKEY") 355 resource record is identical to the DNSKEY record. IANA has 356 allocated RR code TBA1 for the CDNSKEY resource record via expert 357 review. The CDNSKEY RR uses the same registries as DNSKEY for its 358 fields. 360 No special processing is performed by authoritative servers or by 361 revolvers, when serving or resolving. For all practical purposes 362 CDNSKEY is a regular RR type. 364 4. Automating DS Maintainance With CDS/CDNSKEY records 366 CDS/CDNSKEY resource records are intended to be "consumed" by 367 delegation trust maintainers. The use of CDS/CDNSKEY is optional. 369 The child SHOULD publish both CDS and CDNSKEY resource records. If 370 the child knows which the parent consumes, it MAY choose to only 371 publish that record type (for example, some children wish the parent 372 to publish a DS, but they wish to keep the DNSKEY "hidden" until 373 needed). If the child publishes both, the two RRsets MUST match in 374 content. The parent should use whichever one they choose, but MUST 375 NOT query for both and perform consistency checks between the CDS and 376 CDNSKEY resource records. 378 4.1. CDS / CDNSKEY Processing Rules 380 If there are no CDS / CDNSKEY RRset in the child, this signals that 381 no change should be made to the current DS set. This means that, 382 once the child and parent are in sync, the child DNS operator MAY 383 remove all CDS and CDNSKEY resource records from the zone. 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." 394 o Continuity: "MUST NOT break the current delegation if applied to 395 DS RRset" 397 If any these conditions fail the CDS / CDNSKEY resource record MUST 398 be ignored. 400 5. CDS / CDNSKEY Publication 402 Child DNS Operator publishes a CDS and / or CDNSKEY resource records. 403 In order to be valid, the CDS / CDNSKEY RRset MUST be compliant with 404 the rules in Section 4.1. When the Parent DS is "in-sync" with the 405 CDS / CDNSKEY resource records, the Child DNS Operator MAY delete the 406 CDS / CDNSKEY record(s); the child can determine if this is the case 407 by quering for DS records in the parent. Note that if the child has 408 published a CDNSKEY RR, the Parent will have to calculate the DS 409 (using the requested digest algorithm) to do the comparison. 411 6. Parent Side CDS / CDNSKEY Consumption 413 The CDS / CDNSKEY RRset SHOULD be used by the Parental Agent to 414 update the DS RRset in the parent zone. The Parental Agent for this 415 uses a tool that understands the CDS / CDNSKEY signing rules from 416 Section 4.1 so it may not be able to use a standard validator. 418 The parent MUST choose to accept either CDS or CDNSKEY resource 419 records (based upon local policy), and MUST NOT expect there to be 420 both. A parent MUST NOT perform a consistency check between CDS and 421 CDNSKEY (other than for informational / debugging use) resource 422 records. 424 6.1. Detecting a Changed CDS / CDNSKEY 426 How the Parental Agent gets the CDS / CDNSKEY RRset may differ, below 427 are two examples as how this can take place. 429 Polling The Parental Agent operates a tool that periodically checks 430 each of the children that has a DS record to see if there is a 431 CDS or CDNSKEY RRset. 433 Pushing The delegation user interface has a button {Fetch DS} when 434 pushed preforms the CDS / CDNSKEY processing. If the Parent 435 zone does not contain DS for this delegation then the "push" 436 SHOULD be ignored. If the Parental Agent displays the contents 437 of the CDS / CDSNKEY to the user and gets confirmation that 438 this represents their key, the Parental Agent MAY use this for 439 initial enrolment (when the Parent zone does not contain the DS 440 for this delgation). 442 In either case the Parental Agent MAY apply additional rules that 443 defer the acceptance of a CDS / CDNSKEY change, these rules may 444 include a condition that the CDS / CDNSKEY remains in place and valid 445 for some time period before it is accepted. It may be appropriate in 446 the "Pushing" case to assume that the Child is ready and thus accept 447 changes without delay. 449 6.1.1. CDS / CDNSKEY Polling 451 This is the only defined use of CDS / CDNSKEY resource records in 452 this document. There are limits to the scaleability of polling 453 techniques, thus some other mechanism is likely to be specified later 454 that addresses CDS / CDNSKEY resource recod usage in the situation 455 where polling does not scale to. Having said that Polling will work 456 in many important cases like enterprises, universities, small TLDs 457 etc. In many regulatory environments the registry is prohibited from 458 talking to the registrant. In most of these cases the registrant has 459 a business relationship with the registrar, and so the registrar can 460 offer this as a service. 462 If the CDS / CDNSKEY RRset does not exist, the Parental Agent MUST 463 take no action. Specifically it MUST NOT delete or alter the 464 existing DS RRset. 466 6.1.2. Other Mechanisms 468 It is assumed that other mechanisms will be implemented to trigger 469 the parent to look for an updated CDS / CDNSKEY RRsets. As the CDS / 470 CDNSKEY resource records are validated with DNSSEC, these mechanisms 471 can be unauthenticated (for example, a child could telephone its 472 parent and request that they process the new CDS or CDNSKEY resource 473 records, an unauthenticated POST could be made to a webserver (with 474 rate-limiting), etc.) 476 Other documents can specify the trigger conditions. 478 6.2. Using the New CDS / CDNSKEY Records 480 Regardless of how the Parental Agent detected changes to a CDS / 481 CDNSKEY RRset, the Parental Agent SHOULD use a DNSSEC validator to 482 obtain a validated CDS / CDNSKEY RRset from the Child zone. The only 483 exception to this is if the parent perfoms some additional validation 484 on the data to confirm that it is the "correct" key. This behavior 485 is NOT RECOMMENDED. 487 The Parental Agent MUST ensure that old versions of the CDS / CDNSKEY 488 RRset do not overwrite newer versions. This MAY be accomplished by 489 checking that the signature inception in the RRSIG for CDS / CDNSKEY 490 RRset is newer and/or the serial number on the child's SOA is 491 greater. This may require the Parental Agent to maintain some state 492 information. 494 The Parental Agent MAY take extra security measures. For example, to 495 mitigate the possibility that a Child's key signing key has been 496 compromised, the Parental Agent may, for example, inform (by email or 497 other methods ) the Child DNS Operator of the change. However the 498 precise out-of-band measures that a parent zone SHOULD take are 499 outside the scope of this document. 501 Once the Parental Agent has obtained a valid CDS / CDNSKEY RRset it 502 MUST check the publication rules from section 4.1. In particular the 503 Parental Agent MUST double check the Continuity rule and do its best 504 not to invalidate the Child zone. Once checked and if the 505 information in the CDS / CDNSKEY and DS differ it may apply the 506 changes to the parent zone. If the parent consumes CDNSKEY, the 507 parent should calculate the DS before doing this comparison. 509 6.2.1. Parent Calculates DS 511 There are cases where the Parent wants to calculate the DS record due 512 to policy reasons. In this case, the Child publishes CDNSKEY records 513 and the parent calculates the DS records on behalf of the children. 515 When a Parent operates in "calculate DS" mode it can operate in one 516 of two sub-modes 518 full it only publishes DS records it calculates from DNSKEY records, 520 augment it will make sure there are DS records for the digest 521 algorithm(s) it requires(s). 523 In the case where the parent fetches the CDNSKEY RRset and calculate 524 the DS it MAY be the case that the DS published in the parent zone is 525 not identical with the data in the CDS resource record made available 526 by the child. 528 7. IANA Considerations 530 IANA has assigned RR Type code 59 for the CDS resource record. This 531 was done for an earlier version of this document[I-D.ds-publish] This 532 document is to become the reference for CDS RRtype. 534 IANA is requested to assign another RR Type for the CDNSKEY, and to 535 replace TBA1 with this value (currntly 60 is still free, it would be 536 nice if that were assigned...) 538 8. Privacy Considerations 540 All of the information handled / transmitted by this protocol is 541 public information published in the DNS. 543 9. Security Considerations 545 This work is for the normal case; when things go wrong there is only 546 so much that automation can fix. 548 If child breaks DNSSEC validation by removing all the DNSKEYs that 549 are represented in the DS set its only repair actions are to contact 550 the parent or restore the DNSKEYs in the DS set. 552 In the event of a compromise of the server or system generating 553 signatures for a zone, an attacker might be able to generate and 554 publish new CDS resource records. The modified CDS recourse records 555 will be picked up by this technique and so may allow the attacker to 556 extend the effective time of his attack. If there a delay in 557 accepting changes to DS, as in [RFC5011], then the attacker needs to 558 hope his activity is not detected before the DS in parent is changed. 559 If this type of change takes place, the child needs to contact the 560 parent (possibly via a registrar web interface) and remove any 561 compromised DS keys. 563 A compromise of the account with the parent (e.g. registrar) will not 564 be mitigated by this technique, as the "new registrant" can delete/ 565 modify the DS records at will. 567 While it may be tempting, this SHOULD NOT be used for initial 568 enrollment of keys since there is no way to ensure that the initial 569 key is the correct one. If is used, strict rules for inclusion of 570 keys like hold down times, challenge data inclusion etc., ought to be 571 used, along with some kind of challenge mechanism. A child cannot 572 use this mechanism to go from signed to unsigned (publishing an empty 573 CDS / CDNSKEY RRset means no-change should be made in the parent). 575 The CDS RR type should allow for enhanced security by simplifying 576 process. Since rollover is automated, updating a DS RRset by other 577 means may be regarded as unusual and subject to extra security 578 checks. 580 As this introduces a new mechanism to update information in the 581 parent it MUST be clear who is fetching the records and creating the 582 appropriate records in the parent zone. Specifically some operations 583 may use other mechanisms than what is described here. For example, a 584 registrar may assume that it is maintaining the DNSSEC key 585 information in the registry, and may have this cached. If the 586 registry is fetching the CDS / CDNSKEY RRset then the registry and 587 registrar may have different views of the DNSSEC key material and the 588 result of such a situation is unclear. Therefore, this mechanism 589 SHOULD NOT be use to bypass intermediaries that might cache 590 information and because of that get the wrong state. 592 If there is a failure in applying changes in child zone to all DNS 593 servers listed in either parent or child NS set it is possible that 594 the Parental agent may get confused, either because it gets different 595 answers on different checks or CDS RR validation fails. In the worst 596 case, the Parental Agent performs an action reversing a prior action 597 but after the child signing system decides to take the next step in 598 rollover, resulting in a broken delegation. 600 DNS is a loosely coherent distributed database with local caching; 601 therefore, it is important to allow old information to expire from 602 caches before deleting DS or DNSKEY records. Similarly, it is 603 important to allow new records to propagate through the DNS before 604 use, see [RFC6781] and [I-D.key-time] 606 It is common practice for users to outsource their DNS hosting to a 607 3rd party DNS provider. In order for that provider to be able to 608 maintain the DNSSEC information some users give the provider their 609 registrar login credentials (which obviously has negative security 610 implications). Deploying the solution described in this document 611 allows the 3rd party DNS provider to maintain the DNSSEC information 612 without giving them the registrar credentials, thereby improving 613 security. 615 By automating the maintenance of the DNSSEC key information (and 616 removing humans from the process), we expect to decrease the number 617 of DNSSEC related outages, which should increase DNSSEC deployment. 619 10. Acknowledgements 621 We would like to thank a large number of folk, including: Mark 622 Andrews, Joe Abley, Jaap Akkerhuis, Roy Arends, Doug Barton, Brian 623 Dickinson, Paul Ebersman, Tony Finch, Jim Galvin, Paul Hoffman, Samir 624 Hussain, Tatuya Jinmei, Olaf Kolkman, Cricket Liu, Stephan Lagerholm, 625 Matt Larson, Marco Sanz, Antoin Verschuren, Suzanne Woolf, Paul 626 Wouters, John Dickinson, Timothe Litt and Edward Lewis. 628 Special thanks to Wes Hardaker for contributing significant text and 629 creating the complementary (CSYNC) solution, and to Patrik Faltstrom, 630 Paul Hoffman, Matthijs Mekking and Mukund Sivaraman for text and in- 631 depth review. 633 There were a number of other folk with whom we discussed this, 634 apologies for not remembering everyone. 636 11. References 638 11.1. Normative References 640 [RFC1035] Mockapetris, P., "Domain names - implementation and 641 specification", STD 13, RFC 1035, November 1987. 643 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 644 Requirement Levels", BCP 14, RFC 2119, March 1997. 646 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 647 Rose, "DNS Security Introduction and Requirements", RFC 648 4033, March 2005. 650 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 651 Rose, "Resource Records for the DNS Security Extensions", 652 RFC 4034, March 2005. 654 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 655 Rose, "Protocol Modifications for the DNS Security 656 Extensions", RFC 4035, March 2005. 658 [RFC5011] StJohns, M., "Automated Updates of DNS Security (DNSSEC) 659 Trust Anchors", STD 74, RFC 5011, September 2007. 661 [RFC6781] Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC 662 Operational Practices, Version 2", RFC 6781, December 663 2012. 665 11.2. Informative References 667 [I-D.auto-cpsync] 668 Mekking, W., "Automated (DNSSEC) Child Parent 669 Synchronization using DNS UPDATE", draft-mekking-dnsop- 670 auto-cpsync-01 (work in progress), December 2010. 672 [I-D.csync] 673 Hardaker, W., "Child To Parent Synchronization in DNS", 674 draft-hardaker-dnsop-csync-02 (work in progress), July 675 2013. 677 [I-D.ds-publish] 678 Barwood, G., "DNS Transport", draft-barwood-dnsop-ds- 679 publish-02 (work in progress), June 2011. 681 [I-D.key-time] 682 Mekking, W., "DNSSEC Key Timing Considerations", draft- 683 ietf-dnsop-dnssec-key-timing-03 (work in progress), July 684 2012. 686 [I-D.parent-zones] 687 Andrews, M., "Updating Parent Zones", draft-andrews-dnsop- 688 update-parent-zones-04 (work in progress), November 2013. 690 [RFC5730] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)", 691 STD 69, RFC 5730, August 2009. 693 [RFC5910] Gould, J. and S. Hollenbeck, "Domain Name System (DNS) 694 Security Extensions Mapping for the Extensible 695 Provisioning Protocol (EPP)", RFC 5910, May 2010. 697 Appendix A. RRR background 699 In the RRR world, the different parties are frequently from different 700 organizations. In the single enterprise world there are also 701 organizational/geographical/cultural separations that affect how 702 information flows from a Child to the parent. 704 Due to the complexity of the different roles and interconnections, 705 automation of delegation information has not yet occured. There have 706 been proposals to automate this, in order to improve the reliability 707 of the DNS. These proposals have not gained enough traction to 708 become standards. 710 For example in many of the TLD cases there is the RRR model 711 (Registry, Registrar and Registrant). The Registry operates DNS for 712 the TLD, the Registrars accept registrations and place information 713 into the Registries database. The Registrant only communicates with 714 the Registrar; frequently the Registry is not allowed to communicate 715 with the Registrant. In that case as far as the registrant is 716 concerned the Registrar == Parent. 718 In many RRR cases the Registrar and Registry communicate via 719 EPP[RFC5730] and use the EPP DNSSEC extension [RFC5910]. In a number 720 of ccTLDs there are other mechanisms in use as well as EPP, but in 721 general there seems to be a movement towards EPP usage when DNSSEC is 722 enabled in the TLD. 724 Appendix B. Changes / Author Notes. 726 [RFC Editor: Please remove this section before publication ] 728 WG-06 to WG-07 730 o Incorporated nits / editorial comments from Tim Wicinski. 732 o 734 * Reference for Mark's draft was incorrect, Wes Hardaker doesn't 735 work for ISC :-P 737 * Normalized CDS record / CDS resource record / records / etc. 739 * Language cleanup / nits / poor grammar. 741 * removed "punted" colloquialism. 743 WG-05 to WG-06 745 o Consensus (according to me!) was that mail thread said "Child MAY 746 remove the CDS record". Changed to accomodate. 748 o "The proposal below can operate with both models, but the child 749 needs to be aware of the parental policies." - removed "but the 750 child needs to be aware of the parental policies.". This is no 751 longer true, as we suggest publishing both CDS and CDSNKEY. 753 o Added: "without some additional out of band process" to "The Child 754 may not enroll the initial key or introduce a new key when there 755 are no old keys that can be used (without some additional, out of 756 band, validation of the keys), because there is no way to validate 757 the information." 759 o Added a bit to the IANA section, requesting that TBA1 be replaced 760 with the IANA allocated code. 762 o Removed" Some parents prefer to accept DNSSEC key information in 763 DS format, some parents prefer to accept it in DNSKEY format, and 764 calculate the DS record on the child's behalf. Each method has 765 pros and cons, both technical and policy. This solution is DS vs 766 DNSKEY agnostic, and allows operation with either." from Section 4 767 as it is covered in Section 2.2.1 769 o Remove a bunch of comments from the XML. I was getting tired of 770 scrolling past them. If the authors need them back, they are in 771 SVN commit 47. 773 WG-04 to WG-05 775 o More comments from Patrik, Paul and Ed. 777 o Many nits and fixes from Matthijs Mekking. 779 o Outstanding question: Should we remove the "Child SHOULD remove 780 the CDS record" text? Mail sent to list. 782 WG-03 to WG-04 784 o Large number of comments and changes from Patrik. 786 WG-02 to WG-03 788 o Fixed some references to RFC 5011 - from Samir Hussain. 790 o Fixed some spelling / typos - from Samir Hussain. 792 o A number of clarifiations on the meaning on an empty / non- 793 existant CDS RRset - thanks to JINMEI, Tatuya 795 o Be consistent in mentioning both CDS and CDNSKEY throughout the 796 document. 798 WG-01 to WG-02 800 o Many nits and suggestions from Mukund. 802 o Matthijs: " I still think that it is too strong that the Child DNS 803 Operator SHOULD/MUST delete the CDS RRset when the Parent DS is 804 "in-sync". This should be a MAY" 806 WG-00 to WG-01 807 o Addressed Vancouver: "Paul Hoffmann: NOT ready for WGLC. None of 808 the 2 documents explain why there is a split between the two 809 strategies." Thanks to Paul for providing text. 811 From -05 to WG-00: 813 o Nothing rchanged, resubmit under new name. 815 From 04 to 05 817 o Renamed the record back to CDS. 819 From 03 to 04. 821 o Added text explaining that CDS and CSYNC complement each other, 822 not replace or compete. 824 o Changed format of record to be to allow the 825 publication of DS **or** DNSKEY. 827 o Bunch of text changed to cover the above. 829 o Added a bit more text on the polling scaling stuff, expectation 830 that other triggers will be documented. 832 From 02 to 03 834 o Applied comments by Matthijs Mekking 836 o Incorporated suggestions from Edward Lewis about structure 838 o Reworked structure to be easier for implementors to follow 840 o Applied many suggestions from a wonderful thorough review by John 841 Dickinson 843 o Removed the going Unsigned option 845 From 01 to 02 847 o Major restructuring to facilitate easier discussion 849 o Lots of comments from DNSOP mailing list incorporated, including 850 making draft DNSKEY/DS neutral, explain different relationships 851 that exists, 853 o added more people to acks. 855 o added description of enterprise situations 857 o Unified on using Parental Agent over Parental Representative 859 o Removed redundant text when possible 861 o Added text to explain what can go wrong if not all child DNS 862 servers are in sync. 864 o Reference prior work by Matthijs Mekking 866 o Added text when parent calculates DS from DNSKEY 868 From - to -1. 870 o Removed from section .1: "If a child zone has gone unsigned, i.e. 871 no DNSKEY and no RRSIG in the zone, the parental representative 872 MAY treat that as intent to go unsigned. (NEEDS DISCUSSION)." 873 Added new text at end. -- suggestion by Scott Rose 20/Feb/13. 875 o Added some background on the different DNS Delegation operating 876 situations and how they affect interaction of parties. This moved 877 some blocks of text from later sections into here. 879 o Number of textual improvements from Stephan Lagerholm 881 o Added motivation why CDS is needed in CDS definition section 883 o Unified terminology in the document. 885 o Much more background 887 Authors' Addresses 889 Warren Kumari 890 Google 891 1600 Amphitheatre Parkway 892 Mountain View, CA 94043 893 US 895 Email: warren@kumari.net 896 Olafur Gudmundsson 897 Shinkuro Inc. 898 4922 Fairmont Av, Suite 250 899 Bethesda, MD 20814 900 USA 902 Email: ogud@ogud.com 904 George Barwood 905 33 Sandpiper Close 906 Gloucester GL2 4LZ 907 United Kingdom 909 Email: george.barwood@blueyonder.co.uk