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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 DNSOP G. Huston 3 Internet-Draft J. Damas 4 Intended status: Standards Track APNIC 5 Expires: October 7, 2018 W. Kumari 6 Google 7 April 5, 2018 9 A Root Key Trust Anchor Sentinel for DNSSEC 10 draft-ietf-dnsop-kskroll-sentinel-11 12 Abstract 14 The DNS Security Extensions (DNSSEC) were developed to provide origin 15 authentication and integrity protection for DNS data by using digital 16 signatures. These digital signatures can be verified by building a 17 chain of trust starting from a trust anchor and proceeding down to a 18 particular node in the DNS. This document specifies a mechanism that 19 will allow an end user and third parties to determine the trusted key 20 state for the root key of the resolvers that handle that user's DNS 21 queries. Note that this method is only applicable for determing 22 which keys are in the trust store for the root key. 24 There is an example / toy implementation of this at http://www.ksk- 25 test.net . 27 [ This document is being collaborated on in Github at: 28 https://github.com/APNIC-Labs/draft-kskroll-sentinel. The most 29 recent version of the document, open issues, etc should all be 30 available here. The authors (gratefully) accept pull requests. Text 31 in square brackets will be removed before publication. ] 33 [ NOTE: This version uses the labels "root-key-sentinel-is-ta-", and 34 "root-key-sentinel-not-ta-".; older versions of this document used 35 "kskroll-sentinel-is-ta-", "kskroll-sentinel-not-ta-", and before that, "_is-ta-", "_not-ta-". 37 Also note that the format of the tag-index is now zero-filled 38 decimal. Apolgies to those who have began implmenting.] 40 Status of This Memo 42 This Internet-Draft is submitted in full conformance with the 43 provisions of BCP 78 and BCP 79. 45 Internet-Drafts are working documents of the Internet Engineering 46 Task Force (IETF). Note that other groups may also distribute 47 working documents as Internet-Drafts. The list of current Internet- 48 Drafts is at https://datatracker.ietf.org/drafts/current/. 50 Internet-Drafts are draft documents valid for a maximum of six months 51 and may be updated, replaced, or obsoleted by other documents at any 52 time. It is inappropriate to use Internet-Drafts as reference 53 material or to cite them other than as "work in progress." 55 This Internet-Draft will expire on October 7, 2018. 57 Copyright Notice 59 Copyright (c) 2018 IETF Trust and the persons identified as the 60 document authors. All rights reserved. 62 This document is subject to BCP 78 and the IETF Trust's Legal 63 Provisions Relating to IETF Documents 64 (https://trustee.ietf.org/license-info) in effect on the date of 65 publication of this document. Please review these documents 66 carefully, as they describe your rights and restrictions with respect 67 to this document. Code Components extracted from this document must 68 include Simplified BSD License text as described in Section 4.e of 69 the Trust Legal Provisions and are provided without warranty as 70 described in the Simplified BSD License. 72 Table of Contents 74 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 75 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 76 2. Protocol Walkthrough Example . . . . . . . . . . . . . . . . 4 77 3. Sentinel Mechanism in Resolvers . . . . . . . . . . . . . . . 7 78 3.1. Preconditions . . . . . . . . . . . . . . . . . . . . . . 7 79 3.2. Special processing . . . . . . . . . . . . . . . . . . . 8 80 4. Processing Sentinel Results . . . . . . . . . . . . . . . . . 8 81 5. Sentinel Test Result Considerations . . . . . . . . . . . . . 10 82 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 83 7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 12 84 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 85 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 86 10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 12 87 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 88 11.1. Normative References . . . . . . . . . . . . . . . . . . 15 89 11.2. Informative References . . . . . . . . . . . . . . . . . 15 90 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 92 1. Introduction 94 The DNS Security Extensions (DNSSEC) [RFC4033], [RFC4034] and 95 [RFC4035] were developed to provide origin authentication and 96 integrity protection for DNS data by using digital signatures. 97 DNSSEC uses Key Tags to efficiently match signatures to the keys from 98 which they are generated. The Key Tag is a 16-bit value computed 99 from the RDATA portion of a DNSKEY RR using a formula similar to a 100 ones-complement checksum. RRSIG RRs contain a Key Tag field whose 101 value is equal to the Key Tag of the DNSKEY RR that validates the 102 signature. 104 This document specifies how validating resolvers can respond to 105 certain queries in a manner that allows a querier to deduce whether a 106 particular key for the root has been loaded into that resolver's 107 trusted key store. In particular, this response mechanism can be 108 used to determine whether a certain root zone KSK is ready to be used 109 as a trusted key within the context of a key roll by this resolver. 111 There are two primary use cases for this mechanism: 113 o Users want to know whether the resolvers they use are ready for an 114 upcoming root KSK rollover 116 o Researchers want to perform Internet-wide studies about the 117 percentage of users who will be ready for an upcoming root KSK 118 rollover 120 The mechanism described in this document meets both of these use 121 cases. This new mechanism is OPTIONAL to implement and use, although 122 for reasons of supporting broad-based measurement techniques, it is 123 strongly preferred that configurations of DNSSEC-validating resolvers 124 enabled this mechanism by default, allowing for local configuration 125 directives to disable this mechanism if desired. 127 The sentinel test described in this document determines whether a 128 user's browser or operating system looking up the special names that 129 are used in this protocol would be able to validate using the root 130 KSK indicated by the special names. The protocol uses the DNS 131 SERVFAIL response code (RCODE 2) for this purpose because that is the 132 response code that is returned by resolvers when DNSSEC validation 133 fails. If a browser or operating system has multiple resolvers 134 configured, and those resolvers have different properties (for 135 example, one performs DNSSEC validation and one does not), the 136 sentinel mechanism might search among the different resolvers, or 137 might not, depending on how the browser or operating system is 138 configured. 140 Note that the sentinel mechanism described here measures a very 141 different (and likely more useful) metric than [RFC8145]. RFC 8145 142 relies on resolvers reporting towards the root servers a list of 143 locally cached trust anchors for the root zone. Those reports can be 144 used to infer how many resolvers may be impacted by a KSK roll, but 145 not what the user impact of the KSK roll will be. 147 1.1. Terminology 149 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 150 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 151 document are to be interpreted as described in RFC 2119. 153 2. Protocol Walkthrough Example 155 [Ed note: This is currently towards the front of the document; we 156 will make it an appendix at publication time, but until then it is 157 worth having up front, as it makes the rest of the document much 158 easier to understand ] 160 This section provides a non-normative example of how the sentinel 161 mechanism could be used, and what each participant does. It is 162 provided in a conversational tone to be easier to follow. 164 Alice is in charge of the DNS root KSK (Key Signing Key), and would 165 like to roll / replace the key with a new one. She publishes the new 166 KSK, but would like to be able to predict / measure what the impact 167 will be before removing/revoking the old key. The current KSK has a 168 Key Tag of 11112, the new KSK has a Key Tag of 02323. Users want to 169 verify that their resolver will not break after Alice rolls the root 170 KSK key (that is, starts signing with just the KSK whose Key Tag is 171 02323). 173 Bob, Charlie, Dave, Ed are all users. They use the DNS recursive 174 resolvers supplied by their ISPs. They would like to confirm that 175 their ISPs have picked up the new KSK. Bob's ISP does not perform 176 validation. Charlie's ISP does validate, but the resolvers have not 177 yet been upgraded to support this mechanism. Dave and Ed's resolvers 178 have been upgraded to support this mechanism; Dave's resolver has the 179 new KSK, Ed's resolver hasn't managed to install the 02323 KSK in its 180 trust store yet. 182 Geoff is a researcher, and would like to both provide a means for 183 Bob, Charlie, Dave and Ed to be able to perform tests, and also would 184 like to be able to perform Internet-wide measurements of what the 185 impact will be (and report this back to Alice). 187 Geoff sets an authoritative DNS server for example.com, and also a 188 webserver (www.example.com). He adds three address records to 189 example.com: 191 invalid.example.com. IN AAAA 2001:db8::1 193 root-key-sentinel-is-ta-02323.example.com. IN AAAA 2001:db8::1 194 root-key-sentinel-not-ta-02323.example.com. IN AAAA 2001:db8::1 196 Note that the use of "example.com" names and the addresses here are 197 examples. In a real deployment, the domain names need to be under 198 control of the researcher, and the addresses must be real, reachable 199 addresses. 201 Geoff then DNSSEC signs the example.com zone, and intentionally makes 202 the invalid.example.com record invalid/bogus (for example, by editing 203 the signed zone and entering garbage for the signature). Geoff also 204 configures his webserver to listen on 2001:db8::1 and serve a 205 resource (for example, a 1x1 GIF, 1x1.gif) for all of these names. 206 The webserver also serves a webpage (www.example.com) which contains 207 links to these 3 resources (http://invalid.example.com/1x1.gif, 208 http://root-key-sentinel-is-ta-02323.example.com/1x1.gif, 209 http://root-key-sentinel-not-ta-02323.example.com/1x1.gif). 211 Geoff then asks Bob, Charlie, Dave and Ed to browse to 212 www.example.com. Using the methods described in this document, the 213 users can figure out what their fate will be when the 11112 KSK is 214 removed. 216 Bob is not using a validating resolver. This means that he will be 217 able to resolve invalid.example.com (and fetch the 1x1 GIF) - this 218 tells him that the KSK roll does not affect him, and so he will be 219 OK. 221 Charlie's resolvers are validating, but they have not been upgraded 222 to support the KSK sentinel mechanism. Charlie will not be able to 223 fetch the http://invalid.example.com/1x1.gif resource (the 224 invalid.example.com record is bogus, and none of his resolvers will 225 resolve it). He is able to fetch both of the other resources - from 226 this he knows (see the logic below) that he is using legacy, 227 validating resolvers. The KSK sentinel method cannot provided him 228 with a definitive answer to the question of what root trust anchors 229 this resolver is using. 231 Dave's resolvers implement the sentinel method, and have picked up 232 the new KSK. For the same reason as Charlie, he cannot fetch the 233 "invalid" resource. His resolver resolves the root-key-sentinel-is- 234 ta-02323.example.com name normally (it contacts the example.com 235 authoritative servers, etc); as it supports the sentinel mechanism, 236 just before Dave's recursive server send the reply to Dave's stub, it 237 performs the KSK Sentinel check (see below). The QNAME starts with 238 "root-key-sentinel-is-ta-", and the recursive resolver does indeed 239 have a key with the Key Tag of 02323 in its root trust store. This 240 means that that this part of the KSK Sentinel check passes (it is 241 true that Key Tag 02323 is in the trust anchor store), and the 242 recursive resolver replies normally (with the answer provided by the 243 authoritative server). Dave's recursive resolver then resolves the 244 root-key-sentinel-not-ta-02323.example.com name. Once again, it 245 performs the normal resolution process, but because it implements KSK 246 Sentinel (and the QNAME starts with "root-key-sentinel-not-ta-"), 247 just before sending the reply, it performs the KSK Sentinel check. 248 As it has 02323 in it's trust anchor store, the answer to "is this 249 *not* a trust anchor" is false, and so the recursive resolver does 250 not reply with the answer from the authoritative server - instead, it 251 replies with a SERVFAIL (note that replying with SERVFAIL instead of 252 the original answer is the only mechanism that KSK Sentinel uses). 253 This means that Dave cannot fetch "invalid", he can fetch "root-key- 254 sentinel-is-ta-02323", but he cannot fetch "root-key-sentinel-not-ta- 255 02323". From this, Dave knows that he is behind an upgraded, 256 validating resolver, which has successfully installed the new, 02323 257 KSK. 259 Just like Charlie and Dave, Ed cannot fetch the "invalid" record. 260 This tells him that his resolvers are validating. When his 261 (upgraded) resolver performs the KSK Sentinel check for "root-key- 262 sentinel-is-ta-02323", it does *not* have the (new, 02323) KSK in 263 it's trust anchor store. This means check fails, and Ed's recursive 264 resolver converts the (valid) answer into a SERVFAIL error response. 265 It performs the same check for root-key-sentinel-not-ta- 266 02323.example.com; as it does not have the 02323 KSK, it is true that 267 this is not a trust anchor for it, and so it replies normally. This 268 means that Ed cannot fetch the "invalid" resource, he also cannot 269 fetch the "root-key-sentinel-is-ta-02323" resource, but he can fetch 270 the "root-key-sentinel-not-ta-02323" resource. This tells Ed that 271 his resolvers have not installed the new KSK. 273 Geoff would like to do a large scale test and provide the information 274 back to Alice. He uses some mechanism such as causing users to go to 275 a web page to cause a large number of users to attempt to resolve the 276 three resources, and then analyzes the results of the tests to 277 determine what percentage of users will be affected by the KSK 278 rollover event. 280 The above description is a simplified example - it is not anticipated 281 that Bob, Charlie, Dave and Ed will actually look for the absence or 282 presence of web resources; instead, the webpage that they load would 283 likely contain JavaScript (or similar) which displays the result of 284 the tests, sends the results to Geoff, or both. This sentinel 285 mechanism does not rely on the web: it can equally be used by trying 286 to resolve the names (for example, using the common "dig" command) 287 and checking which result in a SERVFAIL. 289 3. Sentinel Mechanism in Resolvers 291 DNSSEC-Validating resolvers that implement this mechanism MUST 292 perform validation of responses in accordance with the DNSSEC 293 response validation specification [RFC4035]. 295 This sentinel mechanism makes use of two special labels: 297 o root-key-sentinel-is-ta- 299 o root-key-sentinel-not-ta- 301 Note that the is specified in the DNS label as unsigned 302 decimal integer (as described in [RFC4034], section 5.3), but zero- 303 padded to five digits (for example, a Key Tag 42 would be represented 304 in the label as 00042). 306 These labels trigger special processing in the resolver when 307 responses from authoritative servers are received. Labels containing 308 "root-key-sentinel-is-ta-" is used to answer the question 309 "Is this the Key Tag a trust anchor which the validating DNS resolver 310 is currently trusting?" Labels containing "root-key-sentinel-not-ta- 311 " is used to answer the question "Is this the Key Tag *not* 312 a trust anchor which the validating DNS resolver is currently 313 trusting?" 315 3.1. Preconditions 317 All of the following conditions must be met to trigger special 318 processing inside resolver code: 320 o The DNS response is DNSSEC validated. 322 o The result of validation is "Secure". 324 o The Checking Disabled (CD) bit in the query is not set. 326 o The QTYPE is either A or AAAA (Query Type value 1 or 28) 328 o The OPCODE is QUERY 330 o The leftmost label of the original QNAME (the name sent in the 331 Question Section in the original query) is either "root-key- 332 sentinel-is-ta-" or "root-key-sentinel-not-ta-" 334 If any one of the preconditions is not met, the resolver MUST NOT 335 alter the DNS response based on the mechanism in this document. 337 3.2. Special processing 339 Responses which fullfill all of the preconditions in Section 3.1 340 require special processing, depending on leftmost label in the QNAME. 342 First, the resolver determines if the numerical value of is 343 equal to any of the Key Tags of an active root zone KSK which is 344 currently trusted by the local resolver and is stored in its store of 345 trusted keys. An active key is one which could currently be used for 346 validation (that is, a key that is not in either the AddPend or 347 Revoked state as described in [RFC5011]). 349 Second, the resolver alters the response being sent to the original 350 query based on both the left-most label and the presence of a key 351 with given Key Tag in the trust anchor store. Two labels and two 352 possible states of the keytag generate four possible combinations 353 summarized in the table: 355 Label | Key Tag is trusted | Key Tag is not trusted 356 ------------------------------------------------------------------ 357 is-ta | return original answer | return SERVFAIL 358 not-ta | return SERVFAIL | return original answer 360 Instruction "return SERVFAIL" means that the resolver MUST set 361 RCODE=SERVFAIL (value 2) and MUST empty the ANSWER section of the DNS 362 response, ignoring all other documents which specify content of the 363 ANSWER section. 365 4. Processing Sentinel Results 367 This proposed test that uses the sentinel detection mechanism 368 described in this document is based on the use of three DNS names 369 that have three distinct DNS resolution behaviours. The test is 370 intended to allow a user or a third party to determine the state of 371 their DNS resolution system, and, in particular, whether or not they 372 are using one or more validating DNS resolvers that use a particular 373 trust anchor for the root zone. 375 The critical aspect of the DNS names used in this mechanism is that 376 they contain the specified label for either the positive and negative 377 test as the left-most label in the query name. 379 The sentinel detection process uses a test with three query names: 381 o A query name containing the left-most label "root-key-sentinel-is- 382 ta-". This corresponds to a a validly-signed RRset in 383 the zone, so that responses associated with queried names in this 384 zone can be authenticated by a DNSSEC-validating resolver. Any 385 validly-signed DNS zone can be used for this test. 387 o A query name containing the left-most label "root-key-sentinel- 388 not-ta-". This is also a validly-signed name. Any 389 validly-signed DNS zone can be used for this test. 391 o A query name that is signed with a DNSSEC signature that cannot be 392 validated (such as if the corresponding RRset is not signed with a 393 valid RRSIG record). 395 The responses received from queries to resolve each of these names 396 would allow us to infer a trust key state of the resolution 397 environment. The techniques describes in this document rely on 398 (DNSSEC validating) resolvers responding with SERVFAIL to valid 399 answers. Note that a slew of other issues can also cause SERVFAIL 400 responses, and so the sentinel processing may sometimes result in 401 incorrect conclusions. 403 To describe this process of classification, we can classify resolvers 404 into four distinct behavior types, for which we will use the labels: 405 "Vnew", "Vold", "Vleg", and "nonV". These labels correspond to 406 resolver behaviour types as follows: 408 Vnew: A DNSSEC-Validating resolver that is configured to implement 409 this mechanism has loaded the nominated key into its local trusted 410 key store will respond with an A or AAAA RRset response for "root- 411 key-sentinel-is-ta" queries, SERVFAIL for "root-key-sentinel-not- 412 ta" queries and SERVFAIL for the invalidly signed name queries. 414 Vold: A DNSSEC-Validating resolver that is configured to implement 415 this mechanism that has not loaded the nominated key into its 416 local trusted key store will respond with an SERVFAIL for "root- 417 key-sentinel-is-ta" queries, an A or AAAA RRset response for 418 "root-key-sentinel-not-ta" queries and SERVFAIL for the invalidly 419 signed name queries. 421 Vleg: A DNSSEC-Validating resolver that does not implement this 422 mechanism will respond with an A or AAAA RRset response for "root- 423 key-sentinel-is-ta", an A or AAAA RRset response for "root-key- 424 sentinel-not-ta" and SERVFAIL for the invalid name. 426 nonV: A non-DNSSEC-Validating resolver will respond with an A or 427 AAAA record response for "root-key-sentinel-is-ta", an A record 428 response for "root-key-sentinel-not-ta" and an A or AAAA RRset 429 response for the invalid name. 431 Given the clear delineation amongst these three cases, if a client 432 directs these three queries to a simple resolver, the variation in 433 response to the three queries should allow the client to determine 434 the category of the resolver, and if it supports this mechanism, 435 whether or not it has a particular key in its trust anchor store. 437 Query 438 +----------+-----------+------------+ 439 | is-ta | not-ta | invalid | 440 +-------+----------+-----------+------------+ 441 | Vnew | A | SERVFAIL | SERVFAIL | 442 | Vold | SERVFAIL | A | SERVFAIL | 443 Type | Vleg | A | A | SERVFAIL | 444 | nonV | A | A | A | 445 +-------+----------+-----------+------------+ 447 A "Vnew" type says that the nominated key is trusted by the resolver 448 and has been loaded into its local trusted key stash. A "Vold" type 449 says that the nominated key is not yet trusted by the resolver in its 450 own right. A "Vleg" type does not give any information about the 451 trust anchors, and a "nonV" type indicates that the resolver does not 452 perform DNSSEC validation. 454 5. Sentinel Test Result Considerations 456 The description in the previous section describes a simple situation 457 where the test queries were being passed to a single recursive 458 resolver that directly queried authoritative name servers, including 459 the root servers. 461 There is also the common case where the end client's browser or 462 operating system is configured to use multiple resolvers. In these 463 cases, a SERVFAIL response from one resolver may cause the end client 464 to repeat the query against one of the other configured resolvers. 465 If the client's browser or operating system does not try the 466 additional resolvers, the sentinel test will effectively only be for 467 the first resolver. 469 If any of the client's resolvers are non-validating resolvers, the 470 tests will result in the client reporting that it has a non- 471 validating DNS environment ("nonV"), which is effectively the case. 473 If all of the client resolvers are DNSSEC-validating resolvers, but 474 some do not support this trusted key mechanism, then the result will 475 be indeterminate with respect to trusted key status ("Vleg"). 476 Simlarly, if all the client's resolvers support this mechanism, but 477 some have loaded the key into the trusted key stash and some have 478 not, then the result is indeterminate ("Vleg"). 480 There is also the common case of a recursive resolver using a 481 forwarder. 483 If the resolver is non-validating, and it has a single forwarder 484 clause, then the resolver will presumably mirror the capabilities of 485 the forwarder target resolver. If this non-validating resolver it 486 has multiple forwarders, then the above considerations will apply. 488 If the validating resolver has a forwarding configuration, and uses 489 the CD bit on all forwarded queries, then this resolver is acting in 490 a manner that is identical to a standalone resolver. The same 491 consideration applies if any one of the forwarder targets is a non- 492 validating resolver. Similarly, if all the forwarder targets do not 493 apply this trusted key mechanism, the same considerations apply. 495 A more complex case is where all of the following conditions all 496 hold: 498 o Both the validating resolver and the forwarder target resolver 499 support this trusted key sentinel mechanism 501 o The local resolver's queries do not have the CD bit set 503 o The trusted key state differs between the forwarding resolver and 504 the forwarder target resolver 506 In such a case, either the outcome is indeterminate validating 507 ("Vleg"), or a case of mixed signals (SERVFAIL in all three 508 responses), which is similarly an indeterminate response with respect 509 to the trusted key state. 511 Please note that SERVFAIL might be cached according to [RFC2308] 512 section 7 for up to 5 minutes and a positive answer for up to its 513 TTL. 515 6. Security Considerations 517 This document describes a mechanism to allow users and third parties 518 to determine the trust state of root zone key signing keys in the DNS 519 resolution system that they use. 521 The mechanism does not require resolvers to set otherwise 522 unauthenticated responses to be marked as authenticated, and does not 523 alter the security properties of DNSSEC with respect to the 524 interpretation of the authenticity of responses that are so marked. 526 The mechanism does not require any further significant processing of 527 DNS responses, and queries of the form described in this document do 528 not impose any additional load that could be exploited in an attack 529 over the the normal DNSSEC validation processing load. 531 7. Privacy Considerations 533 The mechansim in this document enables third parties (with either 534 good or bad intentions) to learn something about the security 535 configuration of recursive name servers. That is, someone who can 536 cause an Internet user to make specific DNS queries (e.g. via web- 537 based advertisements or javascript in web pages), can then determine 538 which trust anchors are configured in the user's resolver. 540 8. IANA Considerations 542 [Note to IANA, to be removed prior to publication: there are no IANA 543 considerations stated in this version of the document.] 545 9. Acknowledgements 547 This document has borrowed extensively from [RFC8145] for the 548 introductory text, and the authors would like to acknowledge and 549 thank the authors of that document both for some text excerpts and 550 for the more general stimulation of thoughts about monitoring the 551 progress of a roll of the KSK of the root zone of the DNS. 553 The authors would like to thank Joe Abley, Mehmet Akcin, Mark 554 Andrews, Richard Barnes, Ray Bellis, Stephane Bortzmeyer, David 555 Conrad, Ralph Dolmans, John Dickinson, Steinar Haug, Bob Harold, Wes 556 Hardaker, Paul Hoffman, Matt Larson, Jinmei Tatuya, Edward Lewis, 557 George Michaelson, Benno Overeinder, Matthew Pounsett, Andreas 558 Schulze, Mukund Sivaraman, Petr Spacek, Andrew Sullivan, Paul Vixie, 559 Duane Wessels and Paul Wouters for their helpful feedback. 561 The authors would like to especially call out Paul Hoffman and Duane 562 Wessels for providing comments in the form of a pull request. Petr 563 Spacek implemented early versions of this technique into the Knot 564 resolver, identified a number of places where it wasn't clear, and 565 provided very helpful text to address this. 567 10. Change Log 569 RFC Editor: Please remove this section! 571 Note that this document is being worked on in GitHub - see Abstract. 572 The below is mainly large changes, and is not authoritative. 574 From -10 to -11: 576 o Clarified the preconditions for this mechanism as per Working 577 Group mailing list discussion. 579 o Corrected minor typo. 581 From -09 to -10: 583 o Clarified the precondition list to specify that the resolver had 584 performed DNSSEC-validation by setting the AD bit in the response 586 o Clarified the language referring to the operation of RFC8145 587 signalling. 589 From -08 to -09: 591 o Incorporated Paul Hoffman's PR # 15 (Two issues from the 592 Hackathon) - https://github.com/APNIC-Labs/draft-kskroll-sentinel/ 593 pull/15 595 o Clarifies that the match is on the *original* QNAME. 597 From -08 to -07: 599 o Changed title from "A Sentinel for Detecting Trusted Keys in 600 DNSSEC" to "A Root Key Trust Anchor Sentinel for DNSSEC". 602 o Changed magic string from "kskroll-sentinel-" to "root-key- 603 sentinel-" -- this time for sure, Rocky! 605 From -07 to -06: 607 o Addressed GitHub PR #14: Clarifications regarding caching and 608 SERVFAIL responses 610 o Addressed GitHub PR #12, #13: Clarify situation with multiple 611 resolvers, Fix editorial nits. 613 From -05 to -06: 615 o Paul improved my merging of Petr's text to make it more readable. 616 Minor change, but this is just before the cut-off, so I wanted it 617 maximally readable. 619 From -04 to -05: 621 o Incorporated Duane's #10 622 o Integrated Petr Spacek's Issue - https://github.com/APNIC-Labs/ 623 draft-kskroll-sentinel/issues/9 (note that commit-log incorrectly 624 referred to Duane's PR as number 9, it is actually 10). 626 From -03 to -04: 628 o Addressed GitHub pull requests #4, #5, #6, #7 #8. 630 o Added Duane's privacy concerns 632 o Makes the use cases clearer 634 o Fixed some A/AAAA stuff 636 o Changed the example numbers 638 o Made it clear that names and addresses must be real 640 From -02 to -03: 642 o Integrated / published comments from Paul in GitHub PR #2 - 643 https://github.com/APNIC-Labs/draft-kskroll-sentinel/pull/2 645 o Made the keytag be decimal, not hex (thread / consensus in 646 https://mailarchive.ietf.org/arch/msg/dnsop/ 647 Kg7AtDhFRNw31He8n0_bMr9hBuE ) 649 From -01 to 02: 651 o Removed Address Record definition. 653 o Clarified that many things can cause SERVFAIL. 655 o Made examples FQDN. 657 o Fixed a number of typos. 659 o Had accidentally said that Charlie was using a non-validating 660 resolver in example. 662 o [ TODO(WK): Doc says keytags are hex, is this really what the WG 663 wants? ] 665 o And active key is one that can be used *now* (not e.g AddPend) 667 From -00 to 01: 669 o Added a conversational description of how the system is intended 670 to work. 672 o Clarification that this is for the root. 674 o Changed the label template from _is-ta- to kskroll- 675 sentinel-is-ta-. This is because BIND (at least) will 676 not allow records which start with an underscore to have address 677 records (CNAMEs, yes, A/AAAA no). Some browsers / operating 678 systems also will not fetch resources from names which start with 679 an underscore. 681 11. References 683 11.1. Normative References 685 [RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS 686 NCACHE)", RFC 2308, DOI 10.17487/RFC2308, March 1998, 687 . 689 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 690 Rose, "DNS Security Introduction and Requirements", 691 RFC 4033, DOI 10.17487/RFC4033, March 2005, 692 . 694 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 695 Rose, "Resource Records for the DNS Security Extensions", 696 RFC 4034, DOI 10.17487/RFC4034, March 2005, 697 . 699 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 700 Rose, "Protocol Modifications for the DNS Security 701 Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005, 702 . 704 [RFC5011] StJohns, M., "Automated Updates of DNS Security (DNSSEC) 705 Trust Anchors", STD 74, RFC 5011, DOI 10.17487/RFC5011, 706 September 2007, . 708 11.2. Informative References 710 [RFC8145] Wessels, D., Kumari, W., and P. Hoffman, "Signaling Trust 711 Anchor Knowledge in DNS Security Extensions (DNSSEC)", 712 RFC 8145, DOI 10.17487/RFC8145, April 2017, 713 . 715 Authors' Addresses 717 Geoff Huston 719 Email: gih@apnic.net 720 URI: http://www.apnic.net 722 Joao Silva Damas 724 Email: joao@apnic.net 725 URI: http://www.apnic.net 727 Warren Kumari 729 Email: warren@kumari.net