idnits 2.17.1 draft-ietf-dnsop-delegation-trust-maintainance-02.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- == There are 1 instance of lines with non-RFC2606-compliant FQDNs in the document. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Line 515 has weird spacing: '... full i.e. ...' == Line 518 has weird spacing: '...augment i.e. ...' -- The document date (February 5, 2014) is 3732 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-06) exists of draft-ietf-dnsop-dnssec-key-timing-03 -- No information found for draft-parent-zones - is the name correct? Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 2 comments (--). 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: August 9, 2014 Shinkuro Inc. 6 G. Barwood 8 February 5, 2014 10 Automating DNSSEC delegation trust maintenance 11 draft-ietf-dnsop-delegation-trust-maintainance-02 13 Abstract 15 This document describes a method to allow DNS operators to more 16 easily update DNSSEC Key Signing Keys using DNS as communication 17 channel. This document does not address the initial configuration of 18 trust anchors for a domain. The technique described is aimed at 19 delegations in which it is currently hard to move information from 20 the child to parent. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on August 9, 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 . . . . . . . . . . . . . 9 69 5. Child's CDS / CDNSKEY Publication . . . . . . . . . . . . . . 9 70 6. Parent side CDS / CDNSKEY Consumption . . . . . . . . . . . . 9 71 6.1. Detecting a changed CDS / CDNSKEY . . . . . . . . . . . . 10 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 . . . . . . . . . . . . . . . . . . . . . . 13 80 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 81 11.1. Normative References . . . . . . . . . . . . . . . . . . 14 82 11.2. Informative References . . . . . . . . . . . . . . . . . 14 83 Appendix A. RRR background . . . . . . . . . . . . . . . . . . . 15 84 Appendix B. Changes / Author Notes. . . . . . . . . . . . . . . 16 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 87 1. Introduction 89 When a DNS operator first signs their zone, they need to communicate 90 their DS record(s) (or DNSKEY(s)) to their parent through some out- 91 of-band method to complete the chain of trust. 93 Each time the child changes/rolls the key that is represented in the 94 parent, the new and/or deleted key information has to be communicated 95 to the parent and published there. How this information is sent to 96 the parent depends on the relationship the child has with the parent. 98 In many cases this is a manual process, and not an easy one. For 99 each key roll, there may be two interactions with the parent. Any 100 manual process is susceptible to mistakes and/or errors. In 101 addition, due to the annoyance factor of the process, operators may 102 avoid performing key rollovers or skip needed steps to publish the 103 new DS at the parent. 105 DNSSEC provides data integrity to information published in DNS; thus 106 DNS publication can be used to automate maintenance of delegation 107 information. This document describes a method to automate 108 publication of subsequent DS records, after the initial one has been 109 published. 111 Readers are expected to be familiar with DNSSEC, including [RFC4033], 112 [RFC4034], [RFC4035], [RFC5011] and [RFC6781]. 114 This document is a compilation of two earlier drafts: draft-barwood- 115 dnsop-ds-publish[I-D.ds-publish] and draft-wkumari-dnsop-ezkeyroll. 117 This document outlines a technique in which the parent periodically 118 (or upon request) polls its signed children and automatically publish 119 new DS records. To a large extent, the procedures this document 120 follows are as described in [RFC6781] section 4.1.2. 122 This technique is in some ways similar to RFC 5011 style rollovers, 123 but for sub-domains DS records, instead of trust anchors. 125 This technique is designed to be friendly both to fully automated 126 tools and humans. Fully automated tools can perform all the actions 127 needed without human intervention, and thus can monitor when it is 128 safe to move to the next step. 130 The solution described in this document only allows transferring 131 information about DNSSEC keys (DS and DNSKEY) from the child to the 132 parental agent. It lists exactly what the parent should publish, and 133 allows for publication of stand-by keys. A different protocol, 134 [I-D.csync], can be used to maintain other important delegation 135 information, such as NS and glue. These two protocols have been kept 136 as separate solutions because the problems are fundamentally 137 different, and a combined solution is overly complex. 139 This document describes a method for automating maintanance of the 140 delegation trust information, and proposes a polled / periodic 141 trigger for simplicity. Some users may prefer a different trigger, 142 such as a button on a webpage, a REST interface, DNS NOTIFY, etc. 143 These alternate / additional triggers are not discussed in this 144 document. 146 1.1. Terminology 148 The terminology we use is defined in this section 150 Highlighted roles 152 o Child: "The entity on record that has the delegation of the domain 153 from the parent" 155 o Parent: "The domain in which the child is registered" 157 o Child DNS operator: "The entity that maintains and publishes the 158 zone information for the child DNS" 160 o Parent DNS operator: "The entity that maintains and publishes the 161 zone information for the parent DNS" 163 o Parental Agent: "The entity that the child has relationship with, 164 to change its delegation information" 166 o Provisioning system: "A system that the operator of the master DNS 167 server operates to maintain the information published in the DNS. 168 This includes the systems that sign the DNS data" 170 RRR is our shorthand for Registry/Registrar/Registrant model of 171 parent child relationship see Appendix A for more. 173 1.2. Requirements notation 175 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 176 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 177 document are to be interpreted as described in [RFC2119]. 179 2. Background 181 2.1. DNS delegations 183 DNS operation consists of delegations of authority. For each 184 delegation there are (most of the time) two parties: the parent and 185 the child. 187 The parent publishes information about the delegations to the child; 188 for the name-servers it publishes an NS [RFC1035] RRset that lists a 189 hint for name-servers that are authoritative for the child. The 190 child also publishes a NS RRset, and this set is the authoritative 191 list of name-servers to the child zone. 193 The second RRset the parent sometimes publishes is the DS [RFC4034] 194 set. The DS RRset provides information about the DNSKEY(s) that the 195 child has told the parent it will use to sign its DNSKEY RRset. In 196 DNSSEC trust relationship between zones is provided by the following 197 chain: 199 parent DNSKEY --> DS --> child DNSKEY. 201 A prior proposal [I-D.auto-cpsync] suggested that the child send an 202 "update" to the parent via a mechanism similar to Dynamic Update. 203 The main issue became: How does the child find the actual parental 204 agent/server to send the update to? While that could have been 205 solved via technical means, the proposal died. There is also a 206 similar proposal in [I-D.parent-zones] 208 As the DS record can only be present at the parent (RFC4034 209 [RFC4034]), some other record/method is needed to automate which 210 DNSKEYs are picked to be represented in the parent zone's DS records. 211 One possibility is to use flags in the DNSKEY record. If the SEP bit 212 is set, this indicates that the DNSKEY is intended for use as a 213 secure entry point. This DNSKEY signs the DNSKEY RRset, and the 214 Parental Agent can calculate DS records based on that. But this 215 fails to meet some operating needs, including the child having no 216 influence what DS digest algorithms are used and DS records can only 217 be published for keys that are in the DNSKEY RRset. 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 email, telephone etc.. This is common 240 when the Child's DNS operator is neither the child itself nor the 241 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 In another common case an enterprise may delegate parts of its name- 254 space to be operated by a group that is not the same as that which 255 operates the enterprise's DNS servers. In this case the flow of 256 information is frequently handled in either an ad hoc manner or via 257 some corporate mechanism; this can range from email to fully- 258 automated operation. The word enterprise above covers all 259 organizations in which the domains are not sold on the open market 260 and there is some relationship between the entities. 262 2.2.1. Solution Space 264 This document is aimed at the cases in which there is an 265 organizational separation of 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. The proposal 287 below can operate with both models, but the child needs to be aware 288 of the parental policies. 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 the delegation account 294 interface, to "upload / paste-in the zone's DS information". The 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 3. CDS / CDNSKEY (Child DS/ Child DNSKEY) record definitions 310 This document specifies two new DNS RRtypes (CDS and CDNSKEY) that 311 indicates what the Child wants the parent's DS RRset to contain. It 312 allows the Child to present DS records and / or DNSKEY records (for 313 those parents who would rather generate the DS records for their 314 children). 316 The CDS / CDNSKEY record is published in the child zone and gives the 317 child control of what is published for it in the parental zone. The 318 CDS / CDNSKEY RRset expresses what the child would like the DS RRset 319 to look like after the change; it is a "replace" operation, and it is 320 up to the consumer of the records to translate that into the 321 appropriate add/delete operations in the registration systems (and in 322 the case of CDNSKEY, to generate the DS from the DNSKEY). 324 [[RFC Editor: Please remove this paragraph before publication] 325 Version -04 of the ID that became this document (http:// 326 tools.ietf.org/id/draft-kumari-ogud-dnsop-cds-04.txt) defined a new 327 record (CTA) that could hold either a DS or a DNSKEY record (with a 328 selector to differentiate between them). In a shocking development, 329 there was almost full consensus that this was horrid :-) ] 331 3.1. CDS Resource Record Format 333 The wire and presentation format of the CDS ("Child DS") record is 334 identical to the DS record [RFC4034]. IANA has allocated RR code 59 335 for the CDS record via expert review [I-D.ds-publish]. 337 No special processing is performed by authoritative servers or by 338 revolvers, when serving or resolving. For all practical purposes CDS 339 is a regular RR type. 341 3.2. CDNSKEY Resource Record Format 343 The wire and presentation format of the CDNSKEY ("Child DNSKEY") 344 record is identical to the DNSKEY record. 346 No special processing is performed by authoritative servers or by 347 revolvers, when serving or resolving. For all practical purposes 348 CDNSKEY is a regular RR type. 350 4. Automating DS maintainance with CDS/CDNSKEY records 352 CDS/CDNSKEY records are intended to be "consumed" by delegation trust 353 maintainers. The use of CDS/CDNSKEY is optional. 355 Some parents prefer to accept DNSSEC key information in DS format, 356 some parents prefer to accept it in DNSKEY format, and calculate the 357 DS record on the child's behalf. Each method has pros and cons, both 358 technical and policy. This solution is DS vs DNSKEY agnostic, and 359 allows operation with either. 361 If the child knows what the parent prefers, they can publish the 362 parent's preferred record type. If the child does not know (or 363 simply chooses to), they can publish both CDS and CDNSKEY. If the 364 child publishes both, they SHOULD have matching CDS records for each 365 CDNSKEY record. The parent should use whichever one they choose, but 366 SHOULD NOT query for both and perform consistency checks between the 367 CDS and CDNSKEY records. 369 [Editor note: It is not an error for a child to have published CDS 370 records and not have CDNSKEYs that hash to those records, nor for 371 there to be CDNSKEY records without matching DS records. This is 372 because a child might have been publishing CDS records and then the 373 parent's policy changes to require CDNSKEY records. The child might 374 forget to remove the CDS, etc. This avoids all sorts of error 375 conditions / complexity, etc.] 377 4.1. CDS / CDNSKEY processing rules 379 Absence of CDS / CDNSKEY in child signals "No change" to the current 380 DS set. Following acceptance rules are placed on the CDS / CDNSKEY 381 records as follows: 383 o Location: "the CDS / CDNSKEY record MUST be at the child zone 384 apex". 386 o Signer: "MUST be signed with a key that is represented in both the 387 current DNSKEY and DS RRset's." 389 o Continuity: "SHOULD NOT break the current delegation if applied to 390 DS RRset" 392 If any these conditions fail the CDS / CDNSKEY record MUST be 393 ignored. 395 5. Child's CDS / CDNSKEY Publication 397 Child DNS Operator SHOULD only publish a CDS or CDNSKEY RRset when it 398 wants to make a change to the DS RRset in the Parent. The CDS / 399 CDNSKEY RRset SHOULD be compliant with the rules in Section 4.1. 400 When the Parent DS is "in-sync" with the CDS, the Child DNS Operator 401 MAY delete the CDS RRset. Note that if the child has published a 402 DNSKEY RR in the CDS, it will have to calculate the DS (using the 403 requested digest algorithm) to do the comparison. 405 A child MAY publish both CDS and CDNSKEY. If a child chooses to 406 publish both, it SHOULD attempt to maintain consistency (a matching 407 CDS for each CDNSKEY) 409 6. Parent side CDS / CDNSKEY Consumption 411 The CDS / CDNSKEY RRset MAY be used by the Parental Agent to update 412 the DS RRset in the parent zone. The Parental Agent for this uses a 413 tool that understands the CDS / CDNSKEY signing rules from 414 Section 4.1 so it may not be able to use a standard validator. 415 Parent SHOULD treat the Continuity rule as "MUST". 417 The parent MUST choose to accept either CDS or CDNSKEY records, and 418 MUST NOT expect there to be both. A parent SHOULD NOT perform a 419 consistency check between CDS and CDNSKEY (other than for 420 informational / debugging use). 422 6.1. Detecting a changed CDS / CDNSKEY 424 How the Parental Agent gets the CDS / CDNSKEY record may differ, 425 below are two examples as how this can take place. 427 Polling The Parental Agent operates a tool that periodically checks 428 each of the children that has a DS record to see if there is a 429 CDS or CDNSKEY record. 431 Pushing The delegation user interface has a button {Fetch DS} when 432 pushed preforms the CDS / CDNSKEY processing. If the Parent 433 zone does not contain DS for this delegation then the "push" 434 MUST be ignored. 436 In either case the Parental Agent MAY apply additional rules that 437 defer the acceptance of a CDS / CDNSKEY change, these rules may 438 include a condition that the CDS / CDNSKEY remains in place and valid 439 for some time period before it is accepted. It may be appropriate in 440 the "Pushing" case to assume that the Child is ready and thus accept 441 changes without delay. 443 6.1.1. CDS / CDNSKEY Polling 445 This is the only defined use of CDS / CDNSKEY in this document. 446 There are limits to the saleability of polling techniques, thus some 447 other mechanism is likely to be specified later that addresses CDS / 448 CDNSKEY usage in the situation where polling does not scale to. 449 Having said that Polling will work in many important cases like 450 enterprises, universities, small TLDs etc. In many regulatory 451 environments the registry is prohibited from talking to the 452 registrant. In most of these cases the registrant has a business 453 relationship with the registrar, and so the registrar can offer this 454 as a service. 456 If the CDS / CDNSKEY RRset does not exist, the Parental Agent MUST 457 take no action. Specifically it MUST NOT delete or alter the 458 existing DS RRset. 460 6.1.2. Other mechanisms 462 It is assumed that other mechanisms will be implemented to trigger 463 the parent to look for an updated CDS / CDNSKEY record. As the CDS / 464 CDNSKEY records are validated with DNSSEC, these mechanisms can be 465 unauthenticated (for example, a child could telephone its parent and 466 request that they process the new CDS or CDNSKEY record, an 467 unauthenticated POST could be made to a webserver (with rate- 468 limiting), etc.) 469 Other documents can specify the trigger conditions. 471 6.2. Using the new CDS / CDNSKEY records 473 Regardless of how the Parental Agent detected changes to a CDS / 474 CDNSKEY RR, the Parental Agent MUST use a DNSSEC validator to obtain 475 a validated CDS / CDNSKEY RRset from the Child zone. It would be a 476 good idea if the Parental Agent checked all NS RRs listed at the 477 delegation. However, due to the use of technologies such as load 478 balancing and anycast, this should not be taken as proof that the new 479 CDS / CDNSKEY is present on all nodes serving the Child zone. 481 The Parental Agent MUST ensure that old versions of the CDS / CDNSKEY 482 RRset do not overwrite newer versions. This MAY be accomplished by 483 checking that the signature inception in the RRSIG for CDS / CDNSKEY 484 is newer and/or the serial number on the child's SOA is greater. 485 This may require the Parental Agent to maintain some state 486 information. 488 The Parental Agent MAY take extra security measures. For example, to 489 mitigate the possibility that a Child's key signing key has been 490 compromised, the Parental Agent may, for example, inform (by email or 491 other methods ) the Child DNS operator of the change. However the 492 precise out-of-band measures that a parent zone SHOULD take are 493 outside the scope of this document. 495 Once the Parental Agent has obtained a valid CDS / CDNSKEY it MAY 496 double check the publication rules from section 4.1. In particular 497 the Parental Agent MUST double check the Continuity rule and do its 498 best not to invalidate the Child zone. Once checked and if the CDS / 499 CDNSKEY and DS "differ" it may apply the changes to the parent zone. 500 If the parent consumes CDNSKEY, the parent should calculate the DS 501 before doing this comparison. 503 6.2.1. Parent calculates DS 505 There are cases where the Parent wants to calculate the DS record due 506 to policy reasons. In this case, the Child publishes CDNSKEY records 507 containing DNSKEYs. 509 The parent calculates the DS records on behalf of the children. The 510 DNS Parent needs to publish guidelines for the children as to what 511 digest algorithms are acceptable in the CDS record. 513 When a Parent operates in "calculate DS" mode it can operate in one 514 of two sub-modes 515 full i.e. it only publishes DS records it calculates from DNSKEY 516 records, 518 augment i.e. it will make sure there are DS records for the digest 519 algorithm(s) it requires(s). 521 Implications on Parental Agent are that the CDNSKEY and DS are not 522 exactly the same after update thus it needs to take that into 523 consideration when checking CDNSKEY records. Same goes for the Child 524 DNS Operator, it needs to be able to detect that the new DS RRset is 525 "equivalent" to the current CDNSKEY RRset, thus it can remove the 526 CDNSKEY RRset. 528 7. IANA Considerations 530 IANA has assigned RR Type code 59 for CDS. This was done for an 531 earlier version of this document[I-D.ds-publish] This document is to 532 become the reference for CDS RRtype. 534 IANA is requested to assign another RR Type for the CDNSKEY. 536 8. Privacy Considerations 538 All of the information handled / transmitted by this protocol is 539 public information published in the DNS. 541 9. Security Considerations 543 This work is for the normal case; when things go wrong there is only 544 so much that automation can fix. 546 If child breaks DNSSEC validation by removing all the DNSKEYs that 547 are represented in the DS set its only repair actions are to contact 548 the parent or restore the DNSKEYs in the DS set. 550 In the event of a compromise of the server or system generating 551 signatures for a zone, an attacker might be able to generate and 552 publish new CDS records. The modified CDS records will be picked up 553 by this technique and so may allow the attacker to extend the 554 effective time of his attack. If there a delay in accepting changes 555 to DS, as in RFC5011, then the attacker needs to hope his activity is 556 not detected before the DS in parent is changed. If this type of 557 change takes place, the child needs to contact the parent (possibly 558 via a registrar web interface) and remove any 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 like hold down times, challenge data inclusion etc., ought to be 568 used, along with some kind of challenge mechanism. 570 The CDS RR type should allow for enhanced security by simplifying 571 process. Since rollover is automated, updating a DS RRset by other 572 means may be regarded as unusual and subject to extra security 573 checks. 575 If there is a failure in applying changes in child zone to all DNS 576 servers listed in either parent or child NS set it is possible that 577 the Parental agent may get confused either not perform action because 578 it gets different answers on different checks or CDS validation 579 fails. In the worst case, Parental Agent performs an action 580 reversing a prior action but after the child signing system decides 581 to take the next step in rollover, resulting in a broken delegation. 583 DNS is a loosely coherent distributed database with local caching; 584 therefore, it is important to allow old information to expire from 585 caches before deleting DS or DNSKEY records. Similarly, it is 586 important to allow new records to propagate through the DNS before 587 use, see [RFC6781] and [I-D.key-time] 589 It is common practice for users to outsource their DNS hosting to a 590 3rd party DNS provider. In order for that provider to be able to 591 maintain the DNSSEC information some users give the provider their 592 registrar login credentials (which obviously has negative security 593 implications). Deploying the solution described in this document 594 allows the 3rd party DNS provider to maintain the DNSSEC information 595 without giving them the registrar credentials, thereby improving 596 security. 598 By automating the maintenance of the DNSSEC key information (and 599 removing humans from the process) we expect to decrease the number of 600 DNSSEC related outages, which should increase DNSSEC deployment. 602 10. Acknowledgements 604 We would like to thank a large number of folk, including: Mark 605 Andrews, Joe Abley, Jaap Akkerhuis, Roy Arends, Doug Barton, Brian 606 Dickinson, Paul Ebersman, Tony Finch, Patrik Faltsrom, Jim Galvin, 607 Paul Hoffman, Olaf Kolkman, Cricket Liu, Stephan Lagerholm, Matt 608 Larson, Marco Sanz, Antoin Verschuren, Suzanne Woolf, Paul Wouters, 609 Matthijs Meeking, John Dickinson, Timothe Litt and Edward Lewis. 611 Special thanks to Wes Hardaker for contributing significant text and 612 creating the complementary (CSYNC) solution, and to Paul Hoffman and 613 Mukund Sivaraman for text and review. 615 There were a number of other folk with whom we discussed this, 616 apologies for not remembering everyone. 618 11. References 620 11.1. Normative References 622 [RFC1035] Mockapetris, P., "Domain names - implementation and 623 specification", STD 13, RFC 1035, November 1987. 625 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 626 Requirement Levels", BCP 14, RFC 2119, March 1997. 628 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 629 Rose, "DNS Security Introduction and Requirements", RFC 630 4033, March 2005. 632 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 633 Rose, "Resource Records for the DNS Security Extensions", 634 RFC 4034, March 2005. 636 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 637 Rose, "Protocol Modifications for the DNS Security 638 Extensions", RFC 4035, March 2005. 640 [RFC5011] StJohns, M., "Automated Updates of DNS Security (DNSSEC) 641 Trust Anchors", STD 74, RFC 5011, September 2007. 643 [RFC6781] Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC 644 Operational Practices, Version 2", RFC 6781, December 645 2012. 647 11.2. Informative References 649 [I-D.auto-cpsync] 650 Mekking, W., "Automated (DNSSEC) Child Parent 651 Synchronization using DNS UPDATE", draft-mekking-dnsop- 652 auto-cpsync-01 (work in progress), December 2010. 654 [I-D.csync] 655 Hardaker, W., "Child To Parent Synchronization in DNS", 656 draft-hardaker-dnsop-csync-02 (work in progress), July 657 2013. 659 [I-D.ds-publish] 660 Barwood, G., "DNS Transport", draft-barwood-dnsop-ds- 661 publish-02 (work in progress), June 2011. 663 [I-D.key-time] 664 Mekking, W., "DNSSEC Key Timing Considerations", draft- 665 ietf-dnsop-dnssec-key-timing-03 (work in progress), July 666 2012. 668 [I-D.parent-zones] 669 Andrews, M., "Updating Parent Zones", November 2013. 671 [RFC5730] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)", 672 STD 69, RFC 5730, August 2009. 674 [RFC5910] Gould, J. and S. Hollenbeck, "Domain Name System (DNS) 675 Security Extensions Mapping for the Extensible 676 Provisioning Protocol (EPP)", RFC 5910, May 2010. 678 Appendix A. RRR background 680 In the RRR world, the different parties are frequently from different 681 organizations. In the single enterprise world there are also 682 organizational/geographical/cultural separations that affect how 683 information flows from a Child to the parent. 685 Due to the complexity of the different roles and interconnections, 686 automation of delegation information has been punted in the past. 687 There have been some proposals to automate this, in order to improve 688 the reliability of the DNS. These proposals have not gained enough 689 traction to become standards. 691 For example in many of the TLD cases there is the RRR model 692 (Registry, Registrar and Registrant). The Registry operates DNS for 693 the TLD, the Registrars accept registrations and place information 694 into the Registries database. The Registrant only communicates with 695 the Registrar; frequently the Registry is not allowed to communicate 696 with the Registrant. In that case as far as the registrant is 697 concerned the Registrar == Parent. 699 In many RRR cases the Registrar and Registry communicate via 700 EPP[RFC5730] and use the EPP DNSSEC extension [RFC5910]. In a number 701 of ccTLDs there are other mechanisms in use as well as EPP, but in 702 general there seems to be a movement towards EPP usage when DNSSEC is 703 enabled in the TLD. 705 Appendix B. Changes / Author Notes. 707 [RFC Editor: Please remove this section before publication ] 709 WG-01 to WG-02 711 o Many nits and suggestions from Mukund. 713 o Matthijs: " I still think that it is too strong that the Child DNS 714 Operator SHOULD/MUST delete the CDS RRset when the Parent DS is 715 "in-sync". This should be a MAY" 717 WG-00 to WG-01 719 o Addressed Vancouver: "Paul Hoffmann: NOT ready for WGLC. None of 720 the 2 documents explain why there is a split between the two 721 strategies." Thanks to Paul for providing text. 723 From -05 to WG-00: 725 o Nothing rchanged, resubmit under new name. 727 From 04 to 05 729 o Renamed the record back to CDS. 731 o 733 From 03 to 04. 735 o Added text explaining that CDS and CSYNC complement each other, 736 not replace or compete. 738 o Changed format of record to be to allow the 739 publication of DS **or** DNSKEY. 741 o Bunch of text changed to cover the above. 743 o Added a bit more text on the polling scaling stuff, expecation 744 that other triggers will be documented, 746 From 02 to 03 748 o Applied comments by Matthijs Mekking 750 o Incorporated suggestions from Edward Lewis about structure 752 o Reworked structure to be easier for implementors to follow 753 o Applied many suggestions from a wonderful thorough review by John 754 Dickinson 756 o Removed the going Unsigned option 758 From 01 to 02 760 o Major restructuring to facilitate easier discussion 762 o Lots of comments from DNSOP mailing list incorporated, including 763 making draft DNSKEY/DS neutral, explain different relationships 764 that exists, 766 o added more people to acks. 768 o added description of enterprise situations 770 o Unified on using Parental Agent over Parental Representative 772 o Removed redundant text when possible 774 o Added text to explain what can go wrong if not all child DNS 775 servers are in sync. 777 o Reference prior work by Matthijs Mekking 779 o Added text when parent calculates DS from DNSKEY 781 From - to -1. 783 o Removed from section .1: "If a child zone has gone unsigned, i.e. 784 no DNSKEY and no RRSIG in the zone, the parental representative 785 MAY treat that as intent to go unsigned. (NEEDS DISCUSSION)." 786 Added new text at end. -- suggestion by Scott Rose 20/Feb/13. 788 o Added some background on the different DNS Delegation operating 789 situations and how they affect interaction of parties. This moved 790 some blocks of text from later sections into here. 792 o Number of textual improvements from Stephan Lagerholm 794 o Added motivation why CDS is needed in CDS definition section 796 o Unified terminology in the document. 798 o Much more background 800 Authors' Addresses 802 Warren Kumari 803 Google 804 1600 Amphitheatre Parkway 805 Mountain View, CA 94043 806 US 808 Email: warren@kumari.net 810 Olafur Gudmundsson 811 Shinkuro Inc. 812 4922 Fairmont Av, Suite 250 813 Bethesda, MD 20814 814 USA 816 Email: ogud@ogud.com 818 George Barwood 819 33 Sandpiper Close 820 Gloucester GL2 4LZ 821 United Kingdom 823 Email: george.barwood@blueyonder.co.uk