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Ebersman 3 Internet-Draft Comcast 4 Intended status: Informational C. Griffiths 5 Expires: November 10, 2015 6 W. Kumari 7 Google 8 J. Livingood 9 Comcast 10 R. Weber 11 Nominum 12 May 9, 2015 14 Definition and Use of DNSSEC Negative Trust Anchors 15 draft-ietf-dnsop-negative-trust-anchors-07 17 Abstract 19 DNS Security Extensions (DNSSEC) is now entering widespread 20 deployment. However, domain signing tools and processes are not yet 21 as mature and reliable as those for non-DNSSEC-related domain 22 administration tools and processes. Negative Trust Anchors 23 (described in this document) can be used to mitigate DNSSEC 24 validation failures. 26 [RFC Editor: Please remove this before publication. This document is 27 being stored in github at https://github.com/wkumari/draft-livingood- 28 dnsop-negative-trust-anchors . Authors accept pull requests, and keep 29 the latest (edit buffer) versions there, so commenters can follow 30 along at home.] 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at http://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on November 10, 2015. 49 Copyright Notice 51 Copyright (c) 2015 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (http://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 Table of Contents 66 1. Introduction and motivation . . . . . . . . . . . . . . . . . 3 67 1.1. Definition of a Negative Trust Anchor . . . . . . . . . . 3 68 1.2. Domain Validation Failures . . . . . . . . . . . . . . . 4 69 1.3. End User Reaction . . . . . . . . . . . . . . . . . . . . 4 70 1.4. Switching to a Non-Validating Resolver is Not Recommended 5 71 2. Use of a Negative Trust Anchor . . . . . . . . . . . . . . . 5 72 3. Managing Negative Trust Anchors . . . . . . . . . . . . . . . 7 73 3.1. Alerting Users to NTA Use . . . . . . . . . . . . . . . . 7 74 4. Removal of a Negative Trust Anchor . . . . . . . . . . . . . 7 75 5. Comparison to Other DNS Misconfigurations . . . . . . . . . . 8 76 6. Intentionally Broken Domains . . . . . . . . . . . . . . . . 8 77 7. Discovering broken domains . . . . . . . . . . . . . . . . . 9 78 8. Other Considerations . . . . . . . . . . . . . . . . . . . . 11 79 8.1. Security Considerations . . . . . . . . . . . . . . . . . 11 80 8.2. Privacy Considerations . . . . . . . . . . . . . . . . . 11 81 8.3. IANA Considerations . . . . . . . . . . . . . . . . . . . 11 82 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 83 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 84 10.1. Normative References . . . . . . . . . . . . . . . . . . 12 85 10.2. Informative References . . . . . . . . . . . . . . . . . 12 86 Appendix A. Configuration Examples . . . . . . . . . . . . . . . 13 87 A.1. NLNet Labs Unbound . . . . . . . . . . . . . . . . . . . 13 88 A.2. ISC BIND . . . . . . . . . . . . . . . . . . . . . . . . 13 89 A.3. Nominum Vantio . . . . . . . . . . . . . . . . . . . . . 13 90 Appendix B. Document Change Log . . . . . . . . . . . . . . . . 14 91 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 93 1. Introduction and motivation 95 This document defines a Negative Trust Anchor, which can be used 96 during the transition to ubiquitous DNSSEC deployment. Negative 97 Trust Anchors (NTAs) are configured locally on a validating DNS 98 recursive resolver to shield end users from DNSSEC-related 99 authoritative name server operational errors. Negative Trust Anchors 100 are intended to be temporary, and should not be distributed by IANA 101 or any other organization outside of the administrative boundary of 102 the organization locally implementing a Negative Trust Anchor. 103 Finally, Negative Trust Anchors pertain only to DNSSEC and not to 104 Public Key Infrastructures (PKI) such as X.509. 106 DNSSEC has now entered widespread deployment. However, the DNSSEC 107 signing tools and processes are less mature and reliable than those 108 for non-DNSSEC-related administration. As a result, operators of DNS 109 recursive resolvers, such as Internet Service Providers (ISPs), 110 occasionally observe domains incorrectly managing DNSSEC-related 111 resource records. This mismanagement triggers DNSSEC validation 112 failures, and then causes large numbers of end users to be unable to 113 reach a domain. Many end users tend to interpret this as a failure 114 of their ISP or resolver operator, and may switch to a non-validating 115 resolver or contact their ISP to complain, rather than seeing this as 116 a failure on the part of the domain they wanted to reach. Without 117 the techniques in this document, this pressure may cause the resolver 118 operator to disable (or simply not deploy) DNSSEC validation. Use of 119 a Negative Trust Anchor to temporarily disable DNSSEC validation for 120 a specific misconfigured domain name immediately restores access for 121 end users. This allows the domain's administrators to fix their 122 misconfiguration, while also allowing the organization using the 123 Negative Trust Anchor to keep DNSSEC validation enabled and still 124 reach the misconfigured domain. 126 It is worth noting the following text from [RFC4033] - "In the final 127 analysis, however, authenticating both DNS keys and data is a matter 128 of local policy, which may extend or even override the protocol 129 extensions defined in this document set." A responsibility (one of 130 many) of a caching server operator is to "protect the integrity of 131 the cache." 133 1.1. Definition of a Negative Trust Anchor 135 Trust Anchors are defined in [RFC5914]. A trust anchor should be 136 used by a validating caching resolver as a starting point for 137 building the authentication chain for a signed DNS response. By way 138 of analogy, negative trust anchors stop validation of the 139 authentication chain. Instead, the validator treats any upstream 140 responses as if the zone is unsigned and does not set the AD bit in 141 responses it sends to clients. Note that this is a behavior, and not 142 a separate resource record. This Negative Trust Anchor can 143 potentially be implemented at any level within the chain of trust and 144 would stop validation from that point in the chain down. Validation 145 starts again if there is a positive trust anchor further down in the 146 chain. For example, if there is a NTA at example.com, and a positive 147 trust anchor at foo.bar.example.com, then validation resumes for 148 foo.bar.example.com and anything below it. 150 1.2. Domain Validation Failures 152 A domain name can fail validation for two general reasons: a 153 legitimate security failure such as due to an attack or compromise of 154 some sort, or as a result of misconfiguration on the part of an 155 domain administrator. As domains transition to DNSSEC, the most 156 common reason for a validation failure has been misconfiguration. 157 Thus, domain administrators should be sure to read [RFC6781] in full. 158 They should also pay special attention to Section 4.2, pertaining to 159 key rollovers, which appear to be the cause of many recent validation 160 failures. 162 It is also possible that some DNSSEC validation failures could arise 163 due to differences in how different software developers interpret 164 DNSSEC standards and/or how those developers choose to implement 165 support for DNSSEC. For example, it is conceivable that a domain may 166 be DNSSEC signed properly, and one vendor's DNS recursive resolvers 167 will validate the domain but other vendors' software may fail to 168 validate the domain. 170 1.3. End User Reaction 172 End users generally do not know of, understand, or care about the 173 resolution process that causes connections to happen. This is by 174 design: the point of the DNS is to insulate users from having to 175 remember IP addresses through a friendlier way of naming systems. It 176 follows from this that end users do not, and should not, be expected 177 to know about DNSSEC, validation, or anything of the sort. As a 178 result, end users may misinterpret the failure to reach a domain due 179 to DNSSEC-related misconfiguration . They may (incorrectly) assume 180 that their ISP is purposely blocking access to the domain or that it 181 is a performance failure on the part of their ISP (especially of the 182 ISP's DNS servers). They may contact their ISP to complain, which 183 will incur cost for their ISP. In addition, they may use online 184 tools and sites to complain of this problem, such as via a blog, web 185 forum, or social media site, which may lead to dissatisfaction on the 186 part of other end users or general criticism of an ISP or operator of 187 a DNS recursive resolver. 189 As end users publicize these failures, others may recommend they 190 switch from security-aware DNS resolvers to resolvers not performing 191 DNSSEC validation. This is a shame since the ISP or other DNS 192 recursive resolver operator is actually doing exactly what they are 193 supposed to do in failing to resolve a domain name; this is the 194 expected result when a domain can no longer be validated and it 195 protects end users from a potential security threat. Use of a 196 Negative Trust Anchor would allow the ISP to specifically remedy the 197 failure to reach that domain, without compromising security for other 198 sites. This would result in a satisfied end user, with minimal 199 impact to the ISP, while maintaining the security of DNSSEC for 200 correctly maintained domains. 202 1.4. Switching to a Non-Validating Resolver is Not Recommended 204 As noted in Section 1.3, some people may consider switching to an 205 alternative, non-validating resolver themselves, or may recommend 206 that others do so. But if a domain fails DNSSEC validation and is 207 inaccessible, this could very well be due to a security-related 208 issue. In order to be as safe and secure as possible, end users 209 should not change to DNS servers that do not perform DNSSEC 210 validation as a workaround, and people should not recommend that 211 others do so either. Domains that fail DNSSEC for legitimate reasons 212 (versus misconfiguration) may be in control of hackers or there could 213 be other significant security issues with the domain. 215 Thus, switching to a non-validating resolver to restore access to a 216 domain that fails DNSSEC validation is not a recommended practice, is 217 bad advice to others, is potentially harmful to end user security. 219 2. Use of a Negative Trust Anchor 221 Technical personnel trained in the operation of DNS servers MUST 222 confirm that a failure is due to misconfiguration, as a similar 223 breakage could have occurred if an attacker gained access to a 224 domain's authoritative servers and modified those records or had the 225 domain pointed to their own rogue authoritative servers. They should 226 also confirm that the domain is not intentionally broken, such as for 227 testing purposes as noted in Section 6. Finally, they should make a 228 reasonable attempt to contact the domain owner of the misconfigured 229 zone, preferably prior to implementing the Negative Trust Anchor. 230 Involving trained technical personnel is costly, but operational 231 experience suggests that this is a very rare event, usually on the 232 order of once per quarter (or even less). 234 It is important to confirm that the comains is still under the 235 ownership / control of the legitimate owner of the domain - this is 236 to ensure that disabling validation for a specific domain does not 237 direct users to an address under an attackers control. Contacting 238 the domain owner allows the resolver operator to determine if the 239 issue is a DNSSEC misconfiguration or an attack. 241 In the case of a validation failure due to misconfiguration of a TLD 242 or popular domain name (such as a top 100 website), content or 243 services in the affected TLD or domain could be inaccessible for a 244 large number of users. In such cases, it may be appropriate to use a 245 Negative Trust Anchor as soon as the misconfiguration is confirmed. 246 An example of a list of "top N" websites is the "Alexa Top 500 Sites 247 on the Web" [Alexa], another example would be to look through 248 historical query logs. 250 Once a domain has been confirmed to fail DNSSEC validation due to a 251 DNSSEC-related misconfiguration, an ISP or other DNS recursive 252 resolver operator may elect to use a Negative Trust Anchor for that 253 domain or sub-domain. This instructs their DNS recursive resolver to 254 temporarily NOT perform DNSSEC validation at or in the misconfigured 255 domain. This immediately restores access to the domain for end users 256 while the domain's administrator corrects the misconfiguration(s). 257 It does not and should not involve turning off validation more 258 broadly. 260 A Negative Trust Anchor MUST only be used for a limited duration. 261 Implementors SHOULD allow the operator using the Negative Trust 262 Anchor to set an end time and date associated with any Negative Trust 263 Anchor. Optimally, this time and date is set in a DNS recursive 264 resolver's configuration, though in the short-term this may also be 265 achieved via other systems or supporting processes. Use of a 266 Negative Trust Anchor MUST NOT be automatic. 268 Finally, a Negative Trust Anchor SHOULD be used only in a specific 269 domain or sub-domain and MUST NOT affect validation of other names up 270 the authentication chain. For example, a Negative Trust Anchor for 271 zone1.example.com would affect only names at or below 272 zone1.example.com, and validation would still be performed on 273 example.com, .com, and the root ("."). This Negative Trust Anchor 274 also SHOULD NOT affect names in another branch of the tree (such as 275 example.net). In another example, a Negative Trust Anchor for 276 example.com would affect only names within example.com, and 277 validation would still be performed on .com, and the root ("."). In 278 this scenario, if there is a (probably manually configured) trust 279 anchor for zone1.example.com, validation would be performed for 280 zone1.example.com and subdomains of zone1.example.com. 282 3. Managing Negative Trust Anchors 284 While Negative Trust Anchors have proven useful during the early 285 stages of DNSSEC adoption, domain owners are ultimately responsible 286 for managing and ensuring their DNS records are configured correctly. 288 Most current implementations of DNS validating resolvers currently 289 follow [RFC4033] on configuring a Trust Anchor using either a public 290 key as in a DNSKEY RR or a hash of a public key as in a DS RR. 292 Different DNS validators may have different configuration names for a 293 Negative Trust Anchor. For examples see Appendix A. 295 It is RECOMMENDED that implmentations warn operators (or treat as an 296 error) if they attempt to add an NTA for a domain that has a 297 configured positive trust anchor. 299 3.1. Alerting Users to NTA Use 301 End users of a DNS recursive resolver or other people may wonder why 302 a domain that fails DNSSEC validation resolves with a supposedly 303 validating resolver. As a result, implementors should consider 304 transparently disclosing those Negative Trust Anchors which are 305 currently in place or were in place in the past, such as on a website 306 [Disclosure-Example]. 308 This is particularly important since there is currently no special 309 DNS query response code that could indicate to end users or 310 applications that a Negative Trust Anchor is in place. Such 311 disclosures should optimally include both the data and time that the 312 Negative Trust Anchor was put in place and when it was removed. 314 4. Removal of a Negative Trust Anchor 316 As explored in Section 8.1, using an NTA once the zone correctly 317 validates can have security considerations. It is therefore 318 RECOMMENDED that NTA implementors SHOULD periodically attempt to 319 validate the domain in question, for the period of time that the 320 Negative Trust Anchor is in place, until such validation is again 321 successful. NTAs MUST expire automatically when their configured 322 lifetime ends. The lifetime MUST NOT exceed a week. Before removing 323 the Negative Trust Anchor, all authoritative resolvers listed in the 324 zone should be checked (due to anycast and load balancers it may not 325 be possible to check all instances). 327 Once all testing succeeds, a Negative Trust Anchor should be removed 328 as soon as is reasonably possible. One possible method to 329 automatically determine when the NTA can be removed is to send a 330 periodic query for type SOA at the NTA node; if it gets a response 331 that it can validate (whether the response was an actual SOA answer 332 or a NOERROR/NODATA with appropriate NSEC/NSEC3 records), the NTA is 333 presumed no longer to be necessary and is removed. Implementations 334 SHOULD, by default, perform this operation. Note that under some 335 circumstances this is undesirable behavior (for example, if 336 www.example.com has a bad signature, but example.com/SOA is fine) and 337 so implementations may wish to allow the operator to override this 338 spot-check / behavior. 340 When removing the NTA, the implementation SHOULD remove all cached 341 entries at and below the NTA node. 343 5. Comparison to Other DNS Misconfigurations 345 Domain administrators are ultimately responsible for managing and 346 ensuring their DNS records are configured correctly. ISPs or other 347 DNS recursive resolver operators cannot and should not correct 348 misconfigured A, CNAME, MX, or other resource records of domains for 349 which they are not authoritative. Expecting non-authoritative 350 entities to protect domain administrators from any misconfiguration 351 of resource records is therefore unrealistic and unreasonable, and in 352 the long-term is harmful to the delegated design of the DNS and could 353 lead to extensive operational instability and/or variation. 355 With DNSSEC breakage, it is often possible to tell that there is a 356 misconfiguration by looking at the data and not needing to guess what 357 it should have been. 359 6. Intentionally Broken Domains 361 Some domains, such as dnssec-failed.org, have been intentionally 362 broken for testing purposes 363 [Measuring-DNSSEC-Validation-of-Website-Visitors] [Netalyzr]. For 364 example, dnssec-failed.org is a DNSSEC-signed domain that is broken. 365 If an end user is querying a validating DNS recursive resolver, then 366 this or other similarly intentionally broken domains should fail to 367 resolve and should result in a "Server Failure" error (RCODE 2, also 368 known as 'SERVFAIL'). If such a domain resolved successfully, then 369 it is a sign that the DNS recursive resolver is not fully validating. 371 Organizations that utilize Negative Trust Anchors should not add a 372 Negative Trust Anchor for any intentionally broken domain. Such 373 additions are prevented by the requirement that the operator attempt 374 to contact the administrators for the zone that has broken DNSSEC. 376 Organizations operating an intentionally broken domain may wish to 377 consider adding a TXT record for the domain to the effect of "This 378 domain is purposely DNSSEC broken for testing purposes". 380 7. Discovering broken domains 382 Discovering that a domain is DNSSEC broken as result of an operator 383 error instead of an attack is not trivial, and the examples here 384 should be vetted by an experienced professional before taking the 385 decision on implementing an negative trust anchor. 387 One of the key thing to look for when looking at a DNSSEC broken 388 domain is consistency and history. It therefore is good if you have 389 the ability to look at the server's DNS traffic over a long period of 390 time or have a database that stores DNS names associated answers 391 (this is often referred to as a "passive DNS database"). Another 392 invaluable tool is dnsviz (http://www.dnsivz.net) which also stores 393 DNSSEC related data historically. The drawback here is that you need 394 to have it test the domain before the incident occurs. 396 The first and easiest thing to check is if the failure of the domain 397 is consistent across different software implementations. If not, you 398 want to inform the vendor where it fails so that the vendor can look 399 more deeply into the issue. 401 The next thing is to figure out what the actual failure mode is. 402 There are several tools to do this, an incomplete list includes: 404 o DNSViz (http://dnsviz.net) 406 o Verisign DNSSEC debugger (http://dnssec-debugger.verisignlabs.com) 408 o iis.se DNS check (http://dnscheck.iis.se) 410 most of these tools are open source and can be installed locally. 411 However, using the tools over the Internet has the advantage of 412 providing visibility from a different point. 414 Once you figure out what the error is, you need to check if it shows 415 consistently around the world and from all authoritative servers. 416 Use DNS Tools (dig) or DNS looking glasses to verify this. An error 417 that is consistently the same is more likely to be operator caused 418 than an attack. Also if the output from the authoritative server is 419 consistently different from the resolvers output this hints to an 420 attack rather then an error, unless there is EDNS0 client subnet 421 (draft-ietf-dnsop-edns-client-subnet) applied to the domain. 423 A last check is to look at the actual DNS data. Is the result of the 424 query still the same or has it changed? While a lot of DNSSEC errors 425 occur on events that change DNSSEC data, the actual record someone 426 wants to go to often stays the same. If the data is the same, this 427 is an indication (not a guarantee) that the error is operator caused. 428 Keep in mind that with DNS being used to globally balance traffic the 429 data associated to a name might be different in different parts of 430 the Internet. 432 Here are some examples of common DNSSEC failures that have been seen 433 as operator signing errors on the Internet: 435 o RRSIG timing issue. Each signature has an inception time and 436 expiry time, between which it is valid. Letting this time expire 437 without creating a new signature is one of the most common DNSSEC 438 errors. To a lesser extent, this also occurs if signatures were 439 made active before the inception time. For all of these errors 440 your primary check is to check on the data. Signature expiration 441 is also about the only error we see on actual data (like 442 www.example.com). All other errors are more or less related to 443 dealing with the chain of trust established by DS records in the 444 parent zone and DNSKEYs in the child zones. These mostly occur 445 during key rollovers, but are not limited to that. 447 o DNSKEYs in child zone don't match the DS record in the parent 448 zone. There is a big variation of this that can happen at any 449 point in the key lifecycle. DNSViz is the best tools to show 450 problems in the chain. If you debug yourself use dig +multiline 451 so that you can see the key id of a DNSKEY. Common Variations of 452 this can be: 454 * DS pointing to a non existent key in the child zone. Questions 455 for consideration here include: Has there ever been a key (and, 456 if so, was it used)? Has there been a recent change in the 457 DNSKEY RRSet (indicating a key rollover)? Has the actual data 458 in the zone changed? Is the zone DNSSEC signed at all and has 459 it been in the past? 461 * DS pointing to an existent key, but no signatures are made with 462 the key. The checks above should be done, with the addition of 463 checking if another key in the DNSKEY RRSet is now used to sign 464 the records. 466 * Data in DS or DNSKEY doesn't match the other. This is more 467 common in initial setup when there was a copy and paste error. 468 Again checking history on data is the best you can do there. 470 All of the above is just a starting point for consideration when 471 deciding whether or not to deploy a trust anchor. It is not possible 472 to provide a simple checklist to run through to determine if a domain 473 is broken because of an attack or an operator error. 475 8. Other Considerations 477 8.1. Security Considerations 479 End to end DNSSEC validation will be disabled during the time that a 480 Negative Trust Anchor is used. In addition, the Negative Trust 481 Anchor may be in place after the point in time when the DNS 482 misconfiguration that caused validation to break has been fixed. 483 Thus, there may be a gap between when a domain has been re-secured 484 and when a Negative Trust Anchor is removed. In addition, a Negative 485 Trust Anchor may be put in place by DNS recursive resolver operators 486 without the knowledge of the authoritative domain administrator for a 487 given domain name. However, attempts SHOULD be made to contact and 488 inform the domain administrator prior to putting the NTA in place. 490 One side effect of implementing an NTA is that it may break client 491 applications that assume that a domain is signed and expect an AD bit 492 in the response. It is expected that many application that require 493 DNSSEC for a domain will perform their own validation, and so this 494 should not be a major issue. 496 8.2. Privacy Considerations 498 There are no privacy considerations in this document. 500 8.3. IANA Considerations 502 There are no IANA considerations in this document. 504 9. Acknowledgements 506 Several people made contributions of text to this document and/or 507 played an important role in the development and evolution of this 508 document. This in some cases included performing a detailed review 509 of this document and then providing feedback and constructive 510 criticism for future revisions, or engaging in a healthy debate over 511 the subject of the document. All of this was helpful and therefore 512 the following individuals merit acknowledgement: Joe Abley,John 513 Barnitz, Tom Creighton, Marco Davids, Brian Dickson, Patrik Falstrom, 514 Tony Finch, Chris Ganster, Olafur Gudmundsson, Peter Hagopian, Wes 515 Hardaker, Paul Hoffman, Shane Kerr, Murray Kucherawy, Rick Lamb, Marc 516 Lampo, Scott Rose, Ted Lemon, Antoin Verschuren, Paul Vixie, Patrik 517 Wallstrom, Nick Weaver 518 Edward Lewis, Evan Hunt, Andew Sullivan and Tatuya Jinmei provided 519 especially large amounts of text and / or detailed review. 521 10. References 523 10.1. Normative References 525 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 526 Rose, "DNS Security Introduction and Requirements", RFC 527 4033, March 2005. 529 [RFC5914] Housley, R., Ashmore, S., and C. Wallace, "Trust Anchor 530 Format", RFC 5914, June 2010. 532 [RFC6781] Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC 533 Operational Practices, Version 2", RFC 6781, December 534 2012. 536 10.2. Informative References 538 [Alexa] Alexa, an Amazon.com Company, "Alexa "The top 500 sites on 539 the web. "", , May 2015, . 541 [Disclosure-Example] 542 Comcast, "faa.gov Failing DNSSEC Validation (Fixed)", 543 Comcast , February 2013, 544 . 547 [Measuring-DNSSEC-Validation-of-Website-Visitors] 548 Mens, J., "Is my Web site being used via a DNSSEC- 549 validator?", July 2012, . 552 [Netalyzr] 553 Weaver, N., Kreibich, C., Nechaev, B., and V. Paxson, 554 "Implications of Netalyzr's DNS Measurements", Securing 555 and Trusting Internet Names, SATIN 2011 SATIN 2011, April 556 2011, . 559 [Unound-Configuration] 560 Wijngaards, W., "Unbound: How to Turn Off DNSSEC", June 561 2010, . 564 Appendix A. Configuration Examples 566 The section contains example configurations to achieve Negative Trust 567 Anchor functionality for the zone foo.example.com. 569 Note: These are simply examples - nameserver operators are expected 570 to test and understand the implications of these operations. Note 571 also that some of available implementations may not implement all 572 recommended functionality in this document. In that case it is 573 advisable to request the developer or vendor of the implementation to 574 support the missing feature, rather than start using the incomplete 575 implementation. 577 A.1. NLNet Labs Unbound 579 Unbound lets us simply disable validation checking for a specific 580 zone. 582 For additional information see [Unound-Configuration] 584 server: 585 domain-insecure: "foo.example.com" 587 A.2. ISC BIND 589 Use the "rndc" command: 591 nta -dump 592 List all negative trust anchors. 593 nta [-lifetime duration] [-force] domain [view] 594 Set a negative trust anchor, disabling DNSSEC validation 595 for the given domain. 596 Using -lifetime specifies the duration of the NTA, up 597 to one week. The default is one hour. 598 Using -force prevents the NTA from expiring before its 599 full lifetime, even if the domain can validate sooner. 600 nta -remove domain [view] 601 Remove a negative trust anchor, re-enabling validation 602 for the given domain. 604 A.3. Nominum Vantio 606 ** 608 *negative-trust-anchors* 610 _Format_: name 611 _Command Channel_: view.update name=world negative-trust- 612 anchors=(foo.example.com) 614 _Command Channel_: resolver.update name=res1 negative-trust- 615 anchors=(foo.example.com) 617 *Description*: Disables DNSSEC validation for a domain, even if the 618 domain is under an existing security root. 620 Appendix B. Document Change Log 622 [RFC Editor: This section is to be removed before publication] 624 -06 to 07 626 Addressed a large number of comments from Paul Hoffman, Scott Rose 627 and some more from Jinmei. 629 -05 to -06 631 o A bunch of comments from Tony Finch. 633 -04 to -05 635 o A large bunch of cleanups from Jinmei. Thanks! 637 o Also clarified that if there is an NTA at foo.bar.baz.example, and 638 a positive *trust anchor* at bar.baz.example, the most specific 639 wins. I'm not very happy with this text, any additional text 640 gratefully accepted... 642 -03 to -04: 644 o Addressed some comment from an email from Jinmei that I had 645 missed. Turns out others had made many of the same comments, and 646 so most had already been addressed. 648 -02 to -03: 650 o Included text from Ralph into Appendix B 652 o A bunch of comments from Andrew Sullivan ('[DNSOP] negative-trust- 653 anchors-02" - Mar 18th) 655 o Updated keywords 657 -01 to -02: 659 o Gah! I forgot to run spell check. And I type like a chimpanzee 660 with bad hand-eye coordination... 662 -00 to -01: 664 o Stole chunks of text from Ed Lewis' mailing list "tirade" :-) 666 o New rndc usage text from Evan. 668 o Deleted the (already resolved) open issues from Appendix C, moved 669 the unresolved issues into github, resolved them! 671 o Clarification that automated removal is best removal method, and 672 how to implement (Evan Hunt) 674 o Clarify that an NTA is not a RR (Rick Lamb) 676 o Grammar fixes. 678 Ind-07 - WG-00: 680 o Simply updated name to reflect WG doc. 682 Individual-00: First version published as an individual draft. 684 Individual-01: Fixed minor typos and grammatical nits. Closed all 685 open editorial items. 687 Individual-02: Simple date change to keep doc from expiring. 688 Substantive updates planned. 690 Individual-03: Changes to address feedback from Paul Vixie, by adding 691 a new section "Limited Time and Scope of Use". Changes to address 692 issues raised by Antoin Verschuren and Patrik Wallstrom, by adding a 693 new section "Intentionally Broken Domains" and added two related 694 references. Added text to address the need for manual investigation, 695 as suggested by Patrik Falstrom. Added a suggestion on notification 696 as suggested by Marc Lampo. Made several additions and changes 697 suggested by Ralf Weber, Wes Hardaker, Nick Weaver, Tony Finch, Shane 698 Kerr, Joe Abley, Murray Kucherawy, Olafur Gudmundsson. 700 Individual-04: Moved the section defining a NTA forward, and added 701 new text to the Abstract and Introduction per feedback from Paul 702 Hoffman. 704 Individual-05: Incorporated feedback from the DNSOP WG list received 705 on 2/17/13 and 2/18/13. This is likely the final version before the 706 IETF 86 draft cutoff date. Updated references to RFC6781 to RFC6781, 707 per March Davids. 709 Individual-06: Added more OPEN issues to continue tracking WG 710 discussion. No changes in the main document - just expanded issue 711 tracking. 713 Individual-07: Refresh document - needs revision and rework before 714 IETF-91. Planning to add more contributors. 716 o Using github issue tracker - go see https://github.com/wkumari/ 717 draft-livingood-dnsop-negative-trust-anchors for more details. 719 o A bunch of readability improvments. 721 o Issue: Notify the domain owner of the validation failure - 722 resolved. 724 o Issue: Make the NTA as specific as possible - resolved. 726 Authors' Addresses 728 Paul Ebersman 729 Comcast 730 One Comcast Center 731 1701 John F. Kennedy Boulevard 732 Philadelphia, PA 19103 733 US 735 Email: ebersman-ietf@dragon.net 737 Chris Griffiths 739 Email: cgriffiths@gmail.com 741 Warren Kumari 742 Google 743 1600 Amphitheatre Parkway 744 Mountain View, CA 94043 745 US 747 Email: warren@kumari.net 748 URI: http://www.google.com 749 Jason Livingood 750 Comcast 751 One Comcast Center 752 1701 John F. Kennedy Boulevard 753 Philadelphia, PA 19103 754 US 756 Email: jason_livingood@cable.comcast.com 757 URI: http://www.comcast.com 759 Ralf Weber 760 Nominum 762 Email: Ralf.Weber@nominum.com 763 URI: http://www.nominum.com