< draft-ietf-dnsop-nsec-ttl-03.txt		draft-ietf-dnsop-nsec-ttl-04.txt >
	dnsop P. van Dijk		dnsop P. van Dijk
	Internet-Draft PowerDNS		Internet-Draft PowerDNS
	Updates: 4034, 4035, 5155, 8198 (if approved) 9 February 2021		Updates: 4034, 4035, 5155, 8198 (if approved) 18 February 2021
	Intended status: Standards Track		Intended status: Standards Track
	Expires: 13 August 2021		Expires: 22 August 2021
	NSEC and NSEC3 TTLs and NSEC Aggressive Use		NSEC and NSEC3 TTLs and NSEC Aggressive Use
	draft-ietf-dnsop-nsec-ttl-03		draft-ietf-dnsop-nsec-ttl-04
	Abstract		Abstract
	Due to a combination of unfortunate wording in earlier documents,		Due to a combination of unfortunate wording in earlier documents,
	aggressive use of NSEC and NSEC3 records may deny names far beyond		aggressive use of NSEC and NSEC3 records may deny names far beyond
	the intended lifetime of a denial. This document changes the		the intended lifetime of a denial. This document changes the
	definition of the NSEC and NSEC3 TTL to correct that situation. This		definition of the NSEC and NSEC3 TTL to correct that situation. This
	document updates RFC 4034, RFC 4035, RFC 5155, and RFC 8198.		document updates RFC 4034, RFC 4035, RFC 5155, and RFC 8198.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 35 ¶		skipping to change at page 1, line 35 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on 13 August 2021.		This Internet-Draft will expire on 22 August 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2021 IETF Trust and the persons identified as the		Copyright (c) 2021 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents (https://trustee.ietf.org/		Provisions Relating to IETF Documents (https://trustee.ietf.org/
	license-info) in effect on the date of publication of this document.		license-info) in effect on the date of publication of this document.
	Please review these documents carefully, as they describe your rights		Please review these documents carefully, as they describe your rights
	skipping to change at page 2, line 11 ¶		skipping to change at page 2, line 11 ¶
	extracted from this document must include Simplified BSD License text		extracted from this document must include Simplified BSD License text
	as described in Section 4.e of the Trust Legal Provisions and are		as described in Section 4.e of the Trust Legal Provisions and are
	provided without warranty as described in the Simplified BSD License.		provided without warranty as described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Conventions and Definitions . . . . . . . . . . . . . . . . . 4		2. Conventions and Definitions . . . . . . . . . . . . . . . . . 4
	3. NSEC and NSEC3 TTL changes . . . . . . . . . . . . . . . . . 4		3. NSEC and NSEC3 TTL changes . . . . . . . . . . . . . . . . . 4
	3.1. Updates to RFC4034 . . . . . . . . . . . . . . . . . . . 4		3.1. Updates to RFC4034 . . . . . . . . . . . . . . . . . . . 4
	3.2. Updates to RFC4035 . . . . . . . . . . . . . . . . . . . 4		3.2. Updates to RFC4035 . . . . . . . . . . . . . . . . . . . 5
	3.3. Updates to RFC5155 . . . . . . . . . . . . . . . . . . . 5		3.3. Updates to RFC5155 . . . . . . . . . . . . . . . . . . . 5
	3.4. Updates to RFC8198 . . . . . . . . . . . . . . . . . . . 5		3.4. Updates to RFC8198 . . . . . . . . . . . . . . . . . . . 6
	3.5. A note on incremental signers . . . . . . . . . . . . . . 6
	4. Zone Operator Considerations . . . . . . . . . . . . . . . . 6		4. Zone Operator Considerations . . . . . . . . . . . . . . . . 6
	4.1. A Note On Wildcards . . . . . . . . . . . . . . . . . . . 6		4.1. A Note On Wildcards . . . . . . . . . . . . . . . . . . . 6
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 6		5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
	7. Normative References . . . . . . . . . . . . . . . . . . . . 6		7. Normative References . . . . . . . . . . . . . . . . . . . . 7
	8. Informative References . . . . . . . . . . . . . . . . . . . 7		8. Informative References . . . . . . . . . . . . . . . . . . . 7
	Appendix A. Implementation Status . . . . . . . . . . . . . . . 7		Appendix A. Implementation Status . . . . . . . . . . . . . . . 7
	Appendix B. Document history . . . . . . . . . . . . . . . . . . 8		Appendix B. Document history . . . . . . . . . . . . . . . . . . 8
	Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 9		Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 9
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10
	1. Introduction		1. Introduction
	[RFC editor: please remove this block before publication.		[RFC editor: please remove this block before publication.
	Earlier notes on this:		Earlier notes on this:
	* https://indico.dns-oarc.net/event/29/sessions/98/#20181013		* https://indico.dns-oarc.net/event/29/sessions/98/#20181013
	(https://indico.dns-oarc.net/event/29/sessions/98/#20181013)		(https://indico.dns-oarc.net/event/29/sessions/98/#20181013)
	skipping to change at page 4, line 21 ¶		skipping to change at page 4, line 21 ¶
	2. Conventions and Definitions		2. Conventions and Definitions
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	3. NSEC and NSEC3 TTL changes		3. NSEC and NSEC3 TTL changes
			The existing texts in [RFC4034], [RFC4035], and [RFC5155] use the
			SHOULD requirement level, but they were written when [RFC4035] still
			said 'However, it seems prudent for resolvers to avoid blocking new
			authoritative data or synthesizing new data on their own'. [RFC8198]
			updated that text to contain 'DNSSEC-enabled validating resolvers
			SHOULD use wildcards and NSEC/NSEC3 resource records to generate
			positive and negative responses until the effective TTLs or
			signatures for those records expire'. This means that correctness of
			NSEC and NSEC3 records, and their TTLs, has become much more
			important. Because of that, the updates in this document upgrade the
			requirement level to MUST.
	3.1. Updates to RFC4034		3.1. Updates to RFC4034
	Where [RFC4034] says:		Where [RFC4034] says:
	| The NSEC RR SHOULD have the same TTL value as the SOA minimum TTL		| The NSEC RR SHOULD have the same TTL value as the SOA minimum TTL
	| field. This is in the spirit of negative caching ([RFC2308]).		| field. This is in the spirit of negative caching ([RFC2308]).
	This is updated to say:		This is updated to say:
	| The TTL of the NSEC RR that is returned MUST be the lesser of the		| The TTL of the NSEC RR that is returned MUST be the lesser of the
	| MINIMUM field of the SOA record and the TTL of the SOA itself.		| MINIMUM field of the SOA record and the TTL of the SOA itself.
	| This matches the definition of the TTL for negative responses in		| This matches the definition of the TTL for negative responses in
	| [RFC2308].		| [RFC2308]. A signer MAY cause the TTL of the NSEC RR to have a
			| deviating value after the SOA record has been updated, to allow
			| for an incremental update of the NSEC chain.
	3.2. Updates to RFC4035		3.2. Updates to RFC4035
	Where [RFC4035] says:		Where [RFC4035] says:
	| The TTL value for any NSEC RR SHOULD be the same as the minimum		| The TTL value for any NSEC RR SHOULD be the same as the minimum
	| TTL value field in the zone SOA RR.		| TTL value field in the zone SOA RR.
	This is updated to say:		This is updated to say:
	| The TTL of the NSEC RR that is returned MUST be the lesser of the		| The TTL of the NSEC RR that is returned MUST be the lesser of the
	| MINIMUM field of the SOA record and the TTL of the SOA itself.		| MINIMUM field of the SOA record and the TTL of the SOA itself.
	| This matches the definition of the TTL for negative responses in		| This matches the definition of the TTL for negative responses in
	| [RFC2308].		| [RFC2308]. A signer MAY cause the TTL of the NSEC RR to have a
			| deviating value after the SOA record has been updated, to allow
			| for an incremental update of the NSEC chain.
	3.3. Updates to RFC5155		3.3. Updates to RFC5155
	Where [RFC5155] says:		Where [RFC5155] says:
	| The NSEC3 RR SHOULD have the same TTL value as the SOA minimum TTL		| The NSEC3 RR SHOULD have the same TTL value as the SOA minimum TTL
	| field. This is in the spirit of negative caching [RFC2308].		| field. This is in the spirit of negative caching [RFC2308].
	This is updated to say:		This is updated to say:
	| The TTL of the NSEC3 RR that is returned MUST be the lesser of the		| The TTL of the NSEC3 RR that is returned MUST be the lesser of the
	| MINIMUM field of the SOA record and the TTL of the SOA itself.		| MINIMUM field of the SOA record and the TTL of the SOA itself.
	| This matches the definition of the TTL for negative responses in		| This matches the definition of the TTL for negative responses in
	| [RFC2308].		| [RFC2308]. A signer MAY cause the TTL of the NSEC RR to have a
			| deviating value after the SOA record has been updated, to allow
			| for an incremental update of the NSEC chain.
	Where [RFC5155] says:		Where [RFC5155] says:
	| o The TTL value for any NSEC3 RR SHOULD be the same as the minimum		| o The TTL value for any NSEC3 RR SHOULD be the same as the minimum
	| TTL value field in the zone SOA RR.		| TTL value field in the zone SOA RR.
	This is updated to say:		This is updated to say:
	| o The TTL value for each NSEC3 RR MUST be the lesser of the		| o The TTL value for each NSEC3 RR MUST be the lesser of the
	| MINIMUM field of the zone SOA RR and the TTL of the zone SOA RR		| MINIMUM field of the zone SOA RR and the TTL of the zone SOA RR
	| itself.		| itself. A signer MAY cause the TTL of the NSEC RR to have a
			| deviating value after the SOA record has been updated, to allow
			| for an incremental update of the NSEC chain.
	3.4. Updates to RFC8198		3.4. Updates to RFC8198
	[RFC8198] section 5.4 (Consideration on TTL) is completely replaced		[RFC8198] section 5.4 (Consideration on TTL) is completely replaced
	by the following text:		by the following text:
	| The TTL value of negative information is especially important,		| The TTL value of negative information is especially important,
	| because newly added domain names cannot be used while the negative		| because newly added domain names cannot be used while the negative
	| information is effective.		| information is effective.
	|		|
	skipping to change at page 6, line 5 ¶		skipping to change at page 6, line 29 ¶
	| A resolver that supports aggressive use of NSEC and NSEC3 MAY		| A resolver that supports aggressive use of NSEC and NSEC3 MAY
	| limit the TTL of NSEC and NSEC3 records to the lesser of the		| limit the TTL of NSEC and NSEC3 records to the lesser of the
	| SOA.MINIMUM field and the TTL of the SOA in a response, if		| SOA.MINIMUM field and the TTL of the SOA in a response, if
	| present. It MAY also use a previously cached SOA for a zone to		| present. It MAY also use a previously cached SOA for a zone to
	| find these values.		| find these values.
	(The third paragraph of the original is removed, and the fourth		(The third paragraph of the original is removed, and the fourth
	paragraph is updated to allow resolvers to also take the lesser of		paragraph is updated to allow resolvers to also take the lesser of
	the SOA TTL and SOA MINIMUM.)		the SOA TTL and SOA MINIMUM.)
	3.5. A note on incremental signers
	Some DNSSEC signer implementations might not (re-)sign whole zones in
	one go, instead spreading the work of updating inception/expiration
	times over some period. Such implementations would not be able to
	update all NSEC or NSEC3 records in the zone instantly either. To
	aid these implementations, we additionally specify the following:
	| If an implementation cannot update all NSEC or NSEC3 TTLs after a
	| SOA change immediately, it MUST still attempt to do so as soon as
	| possible during the signing process.
	4. Zone Operator Considerations		4. Zone Operator Considerations
	If signers & DNS servers for a zone cannot immediately be updated to		If signers & DNS servers for a zone cannot immediately be updated to
	conform to this document, zone operators are encouraged to consider		conform to this document, zone operators are encouraged to consider
	setting their SOA record TTL and the SOA MINIMUM field to the same		setting their SOA record TTL and the SOA MINIMUM field to the same
	value. That way, the TTL used for aggressive NSEC and NSEC3 use		value. That way, the TTL used for aggressive NSEC and NSEC3 use
	matches the SOA TTL for negative responses.		matches the SOA TTL for negative responses.
	4.1. A Note On Wildcards		4.1. A Note On Wildcards
	skipping to change at page 6, line 50 ¶		skipping to change at page 7, line 13 ¶
	than the zone operator intended.		than the zone operator intended.
	6. IANA Considerations		6. IANA Considerations
	IANA is requested to add a reference to this document in the		IANA is requested to add a reference to this document in the
	"Resource Record (RR) TYPEs" subregistry of the "Domain Name System		"Resource Record (RR) TYPEs" subregistry of the "Domain Name System
	(DNS) Parameters" registry, for the NSEC and NSEC3 types.		(DNS) Parameters" registry, for the NSEC and NSEC3 types.
	7. Normative References		7. Normative References
			[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
			Rose, "Protocol Modifications for the DNS Security
			Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
			<https://www.rfc-editor.org/info/rfc4035>.
			[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
			Requirement Levels", BCP 14, RFC 2119,
			DOI 10.17487/RFC2119, March 1997,
			<https://www.rfc-editor.org/info/rfc2119>.
	[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS		[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS
	NCACHE)", RFC 2308, DOI 10.17487/RFC2308, March 1998,		NCACHE)", RFC 2308, DOI 10.17487/RFC2308, March 1998,
	<https://www.rfc-editor.org/info/rfc2308>.		<https://www.rfc-editor.org/info/rfc2308>.
	[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.		[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
	Rose, "Resource Records for the DNS Security Extensions",		Rose, "Resource Records for the DNS Security Extensions",
	RFC 4034, DOI 10.17487/RFC4034, March 2005,		RFC 4034, DOI 10.17487/RFC4034, March 2005,
	<https://www.rfc-editor.org/info/rfc4034>.		<https://www.rfc-editor.org/info/rfc4034>.
	[RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS		[RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
	Security (DNSSEC) Hashed Authenticated Denial of		Security (DNSSEC) Hashed Authenticated Denial of
	Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008,		Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008,
	<https://www.rfc-editor.org/info/rfc5155>.		<https://www.rfc-editor.org/info/rfc5155>.
	[RFC8198] Fujiwara, K., Kato, A., and W. Kumari, "Aggressive Use of		[RFC8198] Fujiwara, K., Kato, A., and W. Kumari, "Aggressive Use of
	DNSSEC-Validated Cache", RFC 8198, DOI 10.17487/RFC8198,		DNSSEC-Validated Cache", RFC 8198, DOI 10.17487/RFC8198,
	July 2017, <https://www.rfc-editor.org/info/rfc8198>.		July 2017, <https://www.rfc-editor.org/info/rfc8198>.
	[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
	Rose, "Protocol Modifications for the DNS Security
	Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
	<https://www.rfc-editor.org/info/rfc4035>.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.
	8. Informative References		8. Informative References
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	Appendix A. Implementation Status		Appendix A. Implementation Status
	[RFC Editor: please remove this section before publication]		[RFC Editor: please remove this section before publication]
	Implemented in PowerDNS Authoritative Server 4.3.0		Implemented in PowerDNS Authoritative Server 4.3.0
	https://doc.powerdns.com/authoritative/dnssec/		https://doc.powerdns.com/authoritative/dnssec/
	operational.html?highlight=ttl#some-notes-on-ttl-usage		operational.html?highlight=ttl#some-notes-on-ttl-usage
	(https://doc.powerdns.com/authoritative/dnssec/		(https://doc.powerdns.com/authoritative/dnssec/
	operational.html?highlight=ttl#some-notes-on-ttl-usage) .		operational.html?highlight=ttl#some-notes-on-ttl-usage) .
	Implemented in BIND 9.16 and up, to be released early 2021		Implemented in BIND 9.16 and up, to be released early 2021
	https://mailarchive.ietf.org/arch/msg/dnsop/ga41J2PPUbmc21--		https://mailarchive.ietf.org/arch/msg/dnsop/ga41J2PPUbmc21--
	dqf3i7_IY6M (https://mailarchive.ietf.org/arch/msg/dnsop/		dqf3i7_IY6M (https://mailarchive.ietf.org/arch/msg/dnsop/
	ga41J2PPUbmc21--dqf3i7_IY6M) https://gitlab.isc.org/isc-projects/		ga41J2PPUbmc21--dqf3i7_IY6M) https://gitlab.isc.org/isc-projects/
	skipping to change at page 9, line 4 ¶		skipping to change at page 9, line 17 ¶
	* reduced requirement level from MUST to SHOULD, like the original		* reduced requirement level from MUST to SHOULD, like the original
	texts		texts
	From draft-ietf-dnsop-nsec-ttl-01 to draft-ietf-dnsop-nsec-ttl-02:		From draft-ietf-dnsop-nsec-ttl-01 to draft-ietf-dnsop-nsec-ttl-02:
	* updated the second bit of wrong text in 5155		* updated the second bit of wrong text in 5155
	From draft-ietf-dnsop-nsec-ttl-02 to draft-ietf-dnsop-nsec-ttl-03:		From draft-ietf-dnsop-nsec-ttl-02 to draft-ietf-dnsop-nsec-ttl-03:
	* document now updates resolver behaviour in 8198		* document now updates resolver behaviour in 8198
	* lots of extra text to clarify what behaviour goes where (thanks		* lots of extra text to clarify what behaviour goes where (thanks
	Paul Hoffman)		Paul Hoffman)
	* replace 'any' with 'each' (thanks Duane)		* replace 'any' with 'each' (thanks Duane)
	* upgraded requirement level to MUST, plus a note on incremental		* upgraded requirement level to MUST, plus a note on incremental
	signers		signers
			From draft-ietf-dnsop-nsec-ttl-03 to draft-ietf-dnsop-nsec-ttl-04:
			* the 'incremental signer exception' is now part of all relevant
			document updates
			* added an explanation for the upgraded requirement level
	Acknowledgements		Acknowledgements
	This document was made possible with the help of the following		This document was made possible with the help of the following
	people:		people:
	* Ralph Dolmans		* Ralph Dolmans
	* Warren Kumari		* Warren Kumari
	* Matthijs Mekking		* Matthijs Mekking
End of changes. 19 change blocks.
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