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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (June 3, 2020) is 1422 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 2845 (Obsoleted by RFC 8945) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 DNSOP Working Group P. van Dijk 3 Internet-Draft PowerDNS 4 Intended status: Standards Track L. Peltan 5 Expires: December 5, 2020 CZ.NIC 6 O. Sury 7 Internet Systems Consortium 8 W. Toorop 9 NLnet Labs 10 L. Vandewoestijne 11 June 3, 2020 13 DNS Catalog Zones 14 draft-ietf-dnsop-dns-catalog-zones-00 16 Abstract 18 This document describes a method for automatic DNS zone provisioning 19 among DNS primary and secondary nameservers by storing and 20 transferring the catalog of zones to be provisioned as one or more 21 regular DNS zones. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on December 5, 2020. 40 Copyright Notice 42 Copyright (c) 2020 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 3. Description . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 4. Catalog Zone Structure . . . . . . . . . . . . . . . . . . . 4 61 4.1. SOA and NS Records . . . . . . . . . . . . . . . . . . . 4 62 4.2. Catalog Zone Schema Version . . . . . . . . . . . . . . . 4 63 4.3. List of Member Zones . . . . . . . . . . . . . . . . . . 4 64 5. Nameserver Behavior . . . . . . . . . . . . . . . . . . . . . 5 65 5.1. General Requirements . . . . . . . . . . . . . . . . . . 5 66 6. Updating Catalog Zones . . . . . . . . . . . . . . . . . . . 7 67 6.1. Implementation Notes . . . . . . . . . . . . . . . . . . 7 68 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 69 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 70 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 71 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 72 10.1. Normative References . . . . . . . . . . . . . . . . . . 8 73 10.2. Informative References . . . . . . . . . . . . . . . . . 9 74 Appendix A. Change History (to be removed before final 75 publication) . . . . . . . . . . . . . . . . . . . . 9 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 78 1. Introduction 80 The data in a DNS zone is synchronized amongst its primary and 81 secondary nameservers using AXFR and IXFR. However, the list of 82 zones served by the primary (called a catalog in [RFC1035]) is not 83 automatically synchronized with the secondaries. To add or remove a 84 zone, the administrator of a DNS nameserver farm not only has to add 85 or remove the zone from the primary, they must also add/remove the 86 zone from all secondaries, either manually or via an external 87 application. This can be both inconvenient and error-prone; it is 88 also dependent on the nameserver implementation. 90 This document describes a method in which the catalog is represented 91 as a regular DNS zone (called a "catalog zone" here), and transferred 92 using DNS zone transfers. As zones are added to or removed from the 93 catalog zone, the changes are propagated to the secondary nameservers 94 in the normal way. The secondary nameservers then add/remove/modify 95 the zones they serve in accordance with the changes to the zone. 97 The contents and representation of catalog zones are described in 98 Section 3. Nameserver behavior is described in Section 5. 100 2. Terminology 102 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 103 "SHOULD", "SHOULD NOT", "RECOMMENDED", "*NOT RECOMMENDED*", "MAY", 104 and "OPTIONAL" in this document are to be interpreted as described in 105 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all 106 capitals, as shown here. 108 Catalog zone 109 A DNS zone containing a DNS catalog, that is, a list of DNS zones. 111 Member zone 112 A DNS zone whose configuration is published inside a catalog zone. 114 $CATZ 115 Used in examples as a placeholder to represent the domain name of 116 the catalog zone itself (c.f. $ORIGIN). 118 3. Description 120 A catalog zone is a specially crafted DNS zone that contains, as DNS 121 zone data: 123 o A list of DNS zones (called "member zones"). 125 Implementations of catalog zones SHOULD ignore any RR in the catalog 126 zone which is meaningless or useless to the implementation. 128 Authoritative servers may be preconfigured with multiple catalog 129 zones, each associated with a different set of configurations. A 130 member zone can as such be reconfigured with a different set of 131 preconfigured settings by removing it as a member of one catalog zone 132 and making it a member of another. 134 An implementation of catalog zones MAY allow the catalog to contain 135 other catalog zones as member zones. 137 Although the contents of a catalog zone are interpreted and acted 138 upon by nameservers, a catalog zone is a regular DNS zone and so must 139 adhere to the standards for such zones. 141 A catalog zone is primarily intended for the management of a farm of 142 authoritative nameservers. It is not expected that the content of 143 catalog zones will be accessible from any recursive nameserver. 145 4. Catalog Zone Structure 147 4.1. SOA and NS Records 149 As with any other DNS zone, a catalog zone MUST have a syntactically 150 correct SOA record and at least one NS record at its apex. 152 The SOA record's SERIAL, REFRESH, RETRY and EXPIRE fields [RFC1035] 153 are used during zone transfer. A catalog zone's SOA SERIAL field 154 MUST increase when an update is made to the catalog zone's contents 155 as per serial number arithmetic defined in [RFC1982]. Otherwise, 156 secondary nameservers might not notice updates to the catalog zone's 157 contents. 159 Should the zone be made available for querying, the SOA record's 160 MINIMUM field's value is the negative cache time (as defined in 161 [RFC2308]). Since recursive nameservers are not expected to be able 162 to access (and subsequently cache) entries from a catalog zone a 163 value of zero (0) is RECOMMENDED. 165 There is no requirement to be able to query the catalog zone via 166 recursive nameservers. Implementations of catalog zones MUST ignore 167 and MUST NOT assume or require NS records at the apex. However, at 168 least one is still required so that catalog zones are syntactically 169 correct DNS zones. A single NS RR with an NSDNAME field containing 170 the absolute name "invalid." is RECOMMENDED [RFC2606]. 172 4.2. Catalog Zone Schema Version 174 The catalog zone schema version is specified by an integer value 175 embeded in a TXT RR named "version.$CATZ". All catalog zones MUST 176 have a TXT RRset named "version.$CATZ" with at least one RR. Primary 177 and secondary nameservers MUST NOT use catalog zones without the 178 expected value in one of the RRs in the "version.$CATZ" TXT RRset, 179 but they may be transferred as ordinary zones. For this memo, the 180 value of one of the RRs in the "version.$CATZ" TXT RRset MUST be set 181 to "2", i.e. 183 version.$CATZ 0 IN TXT "2" 185 NB: Version 1 was used in a draft version of this memo and reflected 186 the implementation first found in BIND 9.11. 188 4.3. List of Member Zones 190 The list of member zones is specified as a collection of domain names 191 under the owner name "zones" where "zones" is a direct child domain 192 of the catalog zone. 194 The names of member zones are represented on the RDATA side (instead 195 of as a part of owner names) so that all valid domain names may be 196 represented regardless of their length [RFC1035]. 198 For example, if a catalog zone lists three zones "example.com.", 199 "example.net." and "example.org.", the RRs would appear as follows: 201 .zones.$CATZ 0 IN PTR example.com. 202 .zones.$CATZ 0 IN PTR example.net. 203 .zones.$CATZ 0 IN PTR example.org. 205 where "" is a label that tags each record in the 206 collection. Nameservers MUST accept catalog zones even with those 207 labels not really unique; they MAY warn the user in such case. 209 Having a large number of member zones in a single RRset may cause the 210 RRset to be too large to be conveyed via DNS messages which make up a 211 zone transfer. Having the zones uniquely tagged with the "" label ensures the list of member zones can be split over multiple 213 DNS messages in a zone transfer. 215 The "" label also enables the state for a zone to be 216 reset. (see Section 6) As long as no zone state needs to be reset at 217 the authoritative nameservers, the unique label associated with a 218 zone SHOULD remain the same. 220 The CLASS field of every RR in a catalog zone MUST be IN (1). 222 The TTL field's value is not specially defined by this memo. Catalog 223 zones are for authoritative nameserver management only and are not 224 intended for general querying via recursive resolvers and therefore a 225 value of zero (0) is RECOMMENDED. 227 Each RRSet of catalog zone, with the exception of zone apex, SHOULD 228 consist of just one RR. It's acceptable to generate owner names with 229 the help of sufficiently strong hash function, with small probablity 230 that unrelated records fall within the same RRSet. 232 5. Nameserver Behavior 234 5.1. General Requirements 236 As it is a regular DNS zone, a catalog zone can be transferred using 237 DNS zone transfers among nameservers. 239 Although they are regular DNS zones, catalog zones contain only 240 information for the management of a set of authoritative nameservers. 241 For this reason, operators may want to limit the systems able to 242 query these zones. It may be inconvenient to serve some contents of 243 catalog zones via DNS queries anyway due to the nature of their 244 representation. A separate method of querying entries inside the 245 catalog zone may be made available by nameserver implementations (see 246 Section 6.1). 248 Catalog updates should be automatic, i.e., when a nameserver that 249 supports catalog zones completes a zone transfer for a catalog zone, 250 it SHOULD apply changes to the catalog within the running nameserver 251 automatically without any manual intervention. 253 As with regular zones, primary and secondary nameservers for a 254 catalog zone may be operated by different administrators. The 255 secondary nameservers may be configured to synchronize catalog zones 256 from the primary, but the primary's administrators may not have any 257 administrative access to the secondaries. 259 A catalog zone can be updated via DNS UPDATE on a reference primary 260 nameserver, or via zone transfers. Nameservers MAY allow loading and 261 transfer of broken zones with incorrect catalog zone syntax (as they 262 are treated as regular zones), but nameservers MUST NOT process such 263 broken zones as catalog zones. For the purpose of catalog 264 processing, the broken catalogs MUST be ignored. If a broken catalog 265 zone was transferred, the newly transferred catalog zone MUST be 266 ignored (but the older copy of the catalog zone SHOULD be left 267 running subject to values in SOA fields). 269 If there is a clash between an existing member zone's name and an 270 incoming member zone's name (via transfer or update), the new 271 instance of the zone MUST be ignored and an error SHOULD be logged. 273 When zones are introduced into a catalog zone, a primary SHOULD first 274 make the new zones available for transfers before making the updated 275 catalog zone available for transfer, or sending NOTIFY for the 276 catalog zone to secondaries. Note that secondary nameservers may 277 attempt to transfer the catalog zone upon refresh timeout, so care 278 must be taken to make the member zones available before any update to 279 the list of member zones is visible in the catalog zone. 281 When zones are deleted from a catalog zone, a primary MAY delete the 282 member zone immediately after notifying secondaries. It is up to the 283 secondary nameserver to handle this condition correctly. 285 When the "" label of a member zone changes, all its 286 associated state MUST be reset, including the zone itself. This can 287 be relevant for example when zone ownership is changed. In that case 288 one does not want the new owner to inherit the metadata. Other 289 situations might be resetting DNSSEC state, or forcing a new zone 290 transfer. A simple removal followed by an addition of the member 291 zone would be insufficient for this purpose because it is infeasible 292 for secondaries to track, due to missed notifies or being offline 293 during the removal/addition. 295 6. Updating Catalog Zones 297 TBD: Explain updating catalog zones using DNS UPDATE. 299 6.1. Implementation Notes 301 Catalog zones on secondary nameservers would have to be setup 302 manually, perhaps as static configuration, similar to how ordinary 303 DNS zones are configured. Members of such catalog zones will be 304 automatically synchronized by the secondary after the catalog zone is 305 configured. 307 An administrator may want to look at data inside a catalog zone. 308 Typical queries might include dumping the list of member zones, 309 dumping a member zone's effective configuration, querying a specific 310 property value of a member zone, etc. Because of the structure of 311 catalog zones, it may not be possible to perform these queries 312 intuitively, or in some cases, at all, using DNS QUERY. For example 313 it is not possible to enumerate the contents of a multi-valued 314 property (such as the list of member zones) with a single QUERY. 315 Implementations are therefore advised to provide a tool that uses 316 either the output of AXFR or an out-of-band method to perform queries 317 on catalog zones. 319 7. Security Considerations 321 As catalog zones are transmitted using DNS zone transfers, it is key 322 for these transfers to be protected from unexpected modifications on 323 the route. So, catalog zone transfers SHOULD be authenticated using 324 TSIG [RFC2845]. A primary nameserver SHOULD NOT serve a catalog zone 325 for transfer without using TSIG and a secondary nameserver SHOULD 326 abandon an update to a catalog zone that was received without using 327 TSIG. 329 Use of DNS UPDATE [RFC2136] to modify the content of catalog zones 330 SHOULD similarly be authenticated using TSIG. 332 Zone transfers of member zones SHOULD similarly be authenticated 333 using TSIG [RFC2845]. The TSIG shared secrets used for member zones 334 MUST NOT be mentioned anywhere in the catalog zone data. However, 335 key identifiers may be shared within catalog zones. 337 Catalog zones do not need to be signed using DNSSEC, their zone 338 transfers being authenticated by TSIG. Signed zones MUST be handled 339 normally by nameservers, and their contents MUST NOT be DNSSEC- 340 validated. 342 8. IANA Considerations 344 This document has no IANA actions. 346 9. Acknowledgements 348 Our deepest thanks and appreciation go to Stephen Morris, Ray Bellis 349 and Witold Krecicki who initiated this draft and did the bulk of the 350 work. 352 Catalog zones originated as the chosen method among various proposals 353 that were evaluated at ISC for easy zone management. The chosen 354 method of storing the catalog as a regular DNS zone was proposed by 355 Stephen Morris. 357 The initial authors discovered that Paul Vixie's earlier [Metazones] 358 proposal implemented a similar approach and reviewed it. Catalog 359 zones borrows some syntax ideas from Metazones, as both share this 360 scheme of representing the catalog as a regular DNS zone. 362 Thanks to Brian Conry, Tony Finch, Evan Hunt, Patrik Lundin, Victoria 363 Risk and Carsten Strettman for reviewing draft proposals and offering 364 comments and suggestions. 366 10. References 368 10.1. Normative References 370 [RFC1035] Mockapetris, P., "Domain names - implementation and 371 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 372 November 1987, . 374 [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, 375 DOI 10.17487/RFC1982, August 1996, 376 . 378 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 379 Requirement Levels", BCP 14, RFC 2119, 380 DOI 10.17487/RFC2119, March 1997, 381 . 383 [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, 384 "Dynamic Updates in the Domain Name System (DNS UPDATE)", 385 RFC 2136, DOI 10.17487/RFC2136, April 1997, 386 . 388 [RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS 389 NCACHE)", RFC 2308, DOI 10.17487/RFC2308, March 1998, 390 . 392 [RFC2606] Eastlake 3rd, D. and A. Panitz, "Reserved Top Level DNS 393 Names", BCP 32, RFC 2606, DOI 10.17487/RFC2606, June 1999, 394 . 396 [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. 397 Wellington, "Secret Key Transaction Authentication for DNS 398 (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, 399 . 401 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 402 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 403 May 2017, . 405 10.2. Informative References 407 [Metazones] 408 Vixie, P., "Federated Domain Name Service Using DNS 409 Metazones", 2005, . 411 Appendix A. Change History (to be removed before final publication) 413 o draft-muks-dnsop-dns-catalog-zones-00 415 Initial public draft. 417 o draft-muks-dnsop-dns-catalog-zones-01 419 Added Witold, Ray as authors. Fixed typos, consistency issues. 420 Fixed references. Updated Area. Removed newly introduced custom 421 RR TYPEs. Changed schema version to 1. Changed TSIG requirement 422 from MUST to SHOULD. Removed restrictive language about use of 423 DNS QUERY. When zones are introduced into a catalog zone, a 424 primary SHOULD first make the new zones available for transfers 425 first (instead of MUST). Updated examples, esp. use IPv6 in 426 examples per Fred Baker. Add catalog zone example. 428 o draft-muks-dnsop-dns-catalog-zones-02 430 Addressed some review comments by Patrik Lundin. 432 o draft-muks-dnsop-dns-catalog-zones-03 434 Revision bump. 436 o draft-muks-dnsop-dns-catalog-zones-04 438 Reordering of sections into more logical order. Separation of 439 multi-valued properties into their own category. 441 o draft-toorop-dnsop-dns-catalog-zones-00 443 New authors to pickup the editor pen on this draft 445 o draft-toorop-dnsop-dns-catalog-zones-01 447 Remove data type definitions for zone properties Removing 448 configuration of member zones through zone properties altogether 450 Remove Open issues and discussion Appendix, which was about zone 451 options (including primary/secondary relationships) only. 453 Authors' Addresses 455 Peter van Dijk 456 PowerDNS 457 Den Haag 458 Netherlands 460 Email: peter.van.dijk@powerdns.com 462 Libor Peltan 463 CZ.NIC 464 CZ 466 Email: libor.peltan@nic.cz 468 Ondrej Sury 469 Internet Systems Consortium 470 CZ 472 Email: ondrej@isc.org 473 Willem Toorop 474 NLnet Labs 475 Science Park 400 476 Amsterdam 1098 XH 477 Netherlands 479 Email: willem@nlnetlabs.nl 481 Leo Vandewoestijne 482 Netherlands 484 Email: leo@dns.company