draft-ietf-dnsop-extended-error-08.txt   draft-ietf-dnsop-extended-error-09.txt 
Network Working Group W. Kumari Network Working Group W. Kumari
Internet-Draft Google Internet-Draft Google
Intended status: Standards Track E. Hunt Intended status: Standards Track E. Hunt
Expires: February 10, 2020 ISC Expires: March 13, 2020 ISC
R. Arends R. Arends
ICANN ICANN
W. Hardaker W. Hardaker
USC/ISI USC/ISI
D. Lawrence D. Lawrence
Oracle + Dyn Oracle + Dyn
August 09, 2019 September 10, 2019
Extended DNS Errors Extended DNS Errors
draft-ietf-dnsop-extended-error-08 draft-ietf-dnsop-extended-error-09
Abstract Abstract
This document defines an extensible method to return additional This document defines an extensible method to return additional
information about the cause of DNS errors. Though created primarily information about the cause of DNS errors. Though created primarily
to extend SERVFAIL to provide additional information about the cause to extend SERVFAIL to provide additional information about the cause
of DNS and DNSSEC failures, the Extended DNS Errors option defined in of DNS and DNSSEC failures, the Extended DNS Errors option defined in
this document allows all response types to contain extended error this document allows all response types to contain extended error
information. information.
skipping to change at page 1, line 42 skipping to change at page 1, line 42
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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 February 10, 2020. This Internet-Draft will expire on March 13, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction and background . . . . . . . . . . . . . . . . . 3 1. Introduction and background . . . . . . . . . . . . . . . . . 3
1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 4
2. Extended Error EDNS0 option format . . . . . . . . . . . . . 4 2. Extended Error EDNS0 option format . . . . . . . . . . . . . 4
3. Use of the Extended DNS Error option . . . . . . . . . . . . 4 3. Defined Extended DNS Errors . . . . . . . . . . . . . . . . . 5
3.1. The INFO-CODE field . . . . . . . . . . . . . . . . . . . 5 3.1. Extended DNS Error Code 0 - Other . . . . . . . . . . . . 5
3.2. The EXTRA-TEXT field . . . . . . . . . . . . . . . . . . 5 3.2. Extended DNS Error Code 1 -
4. Defined Extended DNS Errors . . . . . . . . . . . . . . . . . 5
4.1. Extended DNS Error Code 0 - Other . . . . . . . . . . . . 5
4.2. Extended DNS Error Code 1 -
Unsupported DNSKEY Algorithm . . . . . . . . . . . . . . 5 Unsupported DNSKEY Algorithm . . . . . . . . . . . . . . 5
4.3. Extended DNS Error Code 2 - Unsupported 3.3. Extended DNS Error Code 2 - Unsupported
DS Algorithm . . . . . . . . . . . . . . . . . . . . . . 5 DS Algorithm . . . . . . . . . . . . . . . . . . . . . . 5
4.4. Extended DNS Error Code 3 - Stale Answer . . . . . . . . 5 3.4. Extended DNS Error Code 3 - Stale Answer . . . . . . . . 5
4.5. Extended DNS Error Code 4 - Forged Answer . . . . . . . . 6 3.5. Extended DNS Error Code 4 - Forged Answer . . . . . . . . 5
4.6. Extended DNS Error Code 5 - DNSSEC Indeterminate . . . . 6 3.6. Extended DNS Error Code 5 - DNSSEC Indeterminate . . . . 5
4.7. Extended DNS Error Code 6 - DNSSEC Bogus . . . . . . . . 6 3.7. Extended DNS Error Code 6 - DNSSEC Bogus . . . . . . . . 6
4.8. Extended DNS Error Code 7 - Signature Expired . . . . . . 6 3.8. Extended DNS Error Code 7 - Signature Expired . . . . . . 6
4.9. Extended DNS Error Code 8 - Signature Not Yet Valid . . . 6 3.9. Extended DNS Error Code 8 - Signature Not Yet Valid . . . 6
4.10. Extended DNS Error Code 9 - DNSKEY Missing . . . . . . . 6 3.10. Extended DNS Error Code 9 - DNSKEY Missing . . . . . . . 6
4.11. Extended DNS Error Code 10 - RRSIGs Missing . . . . . . . 6 3.11. Extended DNS Error Code 10 - RRSIGs Missing . . . . . . . 6
4.12. Extended DNS Error Code 11 - No Zone Key Bit Set . . . . 6 3.12. Extended DNS Error Code 11 - No Zone Key Bit Set . . . . 6
4.13. Extended DNS Error Code 12 - NSEC Missing . . . . . . . . 6 3.13. Extended DNS Error Code 12 - NSEC Missing . . . . . . . . 6
4.14. Extended DNS Error Code 13 - Cached Error . . . . . . . . 7 3.14. Extended DNS Error Code 13 - Cached Error . . . . . . . . 6
4.15. Extended DNS Error Code 14 - Not Ready . . . . . . . . . 7 3.15. Extended DNS Error Code 14 - Not Ready . . . . . . . . . 6
4.16. Extended DNS Error Code 15 - Blocked . . . . . . . . . . 7 3.16. Extended DNS Error Code 15 - Blocked . . . . . . . . . . 7
4.17. Extended DNS Error Code 16 - Censored . . . . . . . . . . 7 3.17. Extended DNS Error Code 16 - Censored . . . . . . . . . . 7
4.18. Extended DNS Error Code 17 - Prohibited . . . . . . . . . 7 3.18. Extended DNS Error Code 17 - Prohibited . . . . . . . . . 7
4.19. Extended DNS Error Code 18 - Stale Answer . . . . . . . . 7 3.19. Extended DNS Error Code 18 - Filtered . . . . . . . . . . 7
4.20. Extended DNS Error Code 19 - Lame . . . . . . . . . . . . 7 3.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer . . . 7
4.21. Extended DNS Error Code 20 - Deprecated . . . . . . . . . 8 3.21. Extended DNS Error Code 20 - Lame . . . . . . . . . . . . 7
4.22. Extended DNS Error Code 21 - No Reachable Authority . . . 8 3.22. Extended DNS Error Code 21 - Deprecated . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 3.23. Extended DNS Error Code 22 - No Reachable Authority . . . 8
5.1. A New Extended Error Code EDNS Option . . . . . . . . . . 8 3.24. Extended DNS Error Code 23 - Network Error . . . . . . . 8
5.2. New Double-Index Registry Table for Extended Error Codes 8 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 4.1. A New Extended DNS Error Code EDNS Option . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 4.2. New Registry Table for Extended DNS Error Codes . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References . . . . . . . . . . . . . . . . . . 11 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
8.2. Informative References . . . . . . . . . . . . . . . . . 11 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1. Normative References . . . . . . . . . . . . . . . . . . 11
7.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction and background 1. Introduction and background
There are many reasons that a DNS query may fail, some of them There are many reasons that a DNS query may fail, some of them
transient, some permanent; some can be resolved by querying another transient, some permanent; some can be resolved by querying another
server, some are likely best handled by stopping resolution. server, some are likely best handled by stopping resolution.
Unfortunately, the error signals that a DNS server can return are Unfortunately, the error signals that a DNS server can return are
very limited, and are not very expressive. This means that very limited, and are not very expressive. This means that
applications and resolvers often have to "guess" at what the issue is applications and resolvers often have to "guess" at what the issue is
- e.g. was the answer marked REFUSED because of a lame delegation, or - e.g. was the answer marked REFUSED because of a lame delegation, or
because the nameserver is still starting up and loading zones? Is a because the nameserver is still starting up and loading zones? Is a
SERVFAIL a DNSSEC validation issue, or is the nameserver experiencing SERVFAIL a DNSSEC validation issue, or is the nameserver experiencing
a bad hair day? some other failure?
A good example of issues that would benefit by additional error A good example of issues that would benefit by additional error
information are errors caused by DNSSEC validation issues. When a information are errors caused by DNSSEC validation issues. When a
stub resolver queries a DNSSEC bogus name (using a validating stub resolver queries a name which is DNSSEC bogus (using a
resolver), the stub resolver receives only a SERVFAIL in response. validating resolver), the stub resolver receives only a SERVFAIL in
Unfortunately, SERVFAIL is used to signal many sorts of DNS errors, response. Unfortunately, the SERVFAIL Response Code (RCODE) is used
and so the stub resolver simply asks the next configured DNS to signal many sorts of DNS errors, and so the stub resolvers only
resolver. The result of trying the next resolver is one of two option is to ask the next configured DNS resolver. The result of
outcomes: either the next resolver also validates, a SERVFAIL is trying the next resolver is one of two outcomes: either the next
returned again, and the user gets an (largely) incomprehensible error resolver also validates, and a SERVFAIL is returned again or the next
message; or the next resolver is not a validating resolver, and the resolver is not a validating resolver, and the user is returned a
user is returned a potentially harmful result. potentially harmful result. With an Extended DNS Error (EDE) option
enclosed in the response message, the resolver is able to return a
more descriptive reason as to why any failures happened, or add
additional context to a message containing a NOERROR RCODE.
This document specifies a mechanism to extend (or annotate) DNS This document specifies a mechanism to extend DNS errors to provide
errors to provide additional information about the cause of the additional information about the cause of an error. These extended
error. These extended error codes are specially useful when received DNS error codes described in this document and can be used by any
by resolvers, to return to stub resolvers or to downstream resolvers. system that sends DNS queries and receives a response containing an
Authoritative servers MAY parse and use them, but most error codes EDE option.. Different codes are useful in different circumstances,
would make no sense for them. Authoritative servers may need to and thus different systems (stub resolvers, recursive resolvers, and
generate extended error codes though. authoritative resolvers) might receive and use them.
This document does not allow or prohibit any particular extended
error codes and information be matched with any particular RCODEs.
Some combinations of extended error codes and RCODEs may seem
nonsensical (such as resolver-specific extended error codes in
responses from authoritative servers), so systems interpreting the
extended error codes MUST NOT assume that a combination will make
sense. Receivers MUST be able to accept EDE codes and EXTRA-TEXT in
all messages, including even those with a NOERROR RCODE.
1.1. Requirements notation 1.1. Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Extended Error EDNS0 option format 2. Extended Error EDNS0 option format
This draft uses an EDNS0 ([RFC2671]) option to include Extended DNS This draft uses an EDNS0 ([RFC2671]) option to include Extended DNS
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Field definition details: Field definition details:
o OPTION-CODE, 2 octets (defined in [RFC6891]]), for EDE is TBD. o OPTION-CODE, 2 octets (defined in [RFC6891]]), for EDE is TBD.
[RFC Editor: change TBD to the proper code once assigned by IANA.] [RFC Editor: change TBD to the proper code once assigned by IANA.]
o OPTION-LENGTH, 2 octets ((defined in [RFC6891]]) contains the o OPTION-LENGTH, 2 octets ((defined in [RFC6891]]) contains the
length of the payload (everything after OPTION-LENGTH) in octets length of the payload (everything after OPTION-LENGTH) in octets
and should be 4 plus the length of the EXTRA-TEXT section (which and should be 4 plus the length of the EXTRA-TEXT section (which
may be a zero-length string). may be a zero-length string).
o INFO-CODE, 16-bits, which is the principal contribution of this o INFO-CODE, 16-bits, which is the principal contribution of this
document. document. This 16-bit value, encoded in network (MSB) byte order,
provides the additional context for the RESPONSE-CODE of the DNS
message. The INFO-CODE serves as an index to the "Extended DNS
Errors" registry Section 4.1.
o EXTRA-TEXT, a variable length, UTF-8 encoded, text field that may o EXTRA-TEXT, a variable length, UTF-8 encoded, text field that may
hold additional textual information. Note: EXTRA-TEXT may be zero hold additional textual information. Note: EXTRA-TEXT may be zero
octets in length, indicating there is no EXTRA-TEXT included. octets in length, indicating there is no EXTRA-TEXT included.
Care should be take not to leak private information that an
observer would not otherwise have access to, such as account
numbers.
3. Use of the Extended DNS Error option The Extended DNS Error (EDE) option can be included in any response
(SERVFAIL, NXDOMAIN, REFUSED, and even NOERROR, etc) to a query that
The Extended DNS Error (EDE) is an EDNS option. It can be included
in any response (SERVFAIL, NXDOMAIN, REFUSED, etc) to a query that
includes OPT Pseudo-RR [RFC6891]. This document includes a set of includes OPT Pseudo-RR [RFC6891]. This document includes a set of
initial codepoints (and requests to the IANA to add them to the initial codepoints (and requests to the IANA to add them to the
registry), but is extensible via the IANA registry to allow registry), but is extensible via the IANA registry to allow
additional error and information codes to be defined in the future. additional error and information codes to be defined in the future.
The fields of the Extended DNS Error option are defined further in 3. Defined Extended DNS Errors
the following sub-sections.
3.1. The INFO-CODE field
This 16-bit value, encoded in network (MSB) byte order, provides the
additional context for the RESPONSE-CODE of the DNS message. The
INFO-CODE serves as an index to the "Extended DNS Errors" registry
Section 5.1.
3.2. The EXTRA-TEXT field
The UTF-8-encoded, EXTRA-TEXT field may be zero-length, or may hold
additional information useful to network operators.
4. Defined Extended DNS Errors
This document defines some initial EDE codes. The mechanism is This document defines some initial EDE codes. The mechanism is
intended to be extensible, and additional code-points can be intended to be extensible, and additional code-points can be
registered in the "Extended DNS Errors" registry Section 5.1. The registered in the "Extended DNS Errors" registry Section 4.1. The
INFO-CODE from the EDE EDNS option is used to serve as an index into INFO-CODE from the EDE EDNS option is used to serve as an index into
the "Extended DNS Error codes" IANA registry, the initial values for the "Extended DNS Error" IANA registry, the initial values for which
which are defined in the following sub-sections. are defined in the following sub-sections.
4.1. Extended DNS Error Code 0 - Other 3.1. Extended DNS Error Code 0 - Other
The error in question falls into a category that does not match known The error in question falls into a category that does not match known
extended error codes. Implementations SHOULD include a EXTRA-TEXT extended error codes. Implementations SHOULD include a EXTRA-TEXT
value to augment this error code with additional information. value to augment this error code with additional information.
4.2. Extended DNS Error Code 1 - Unsupported DNSKEY Algorithm 3.2. Extended DNS Error Code 1 - Unsupported DNSKEY Algorithm
The resolver attempted to perform DNSSEC validation, but a DNSKEY The resolver attempted to perform DNSSEC validation, but a DNSKEY
RRSET contained only unknown algorithms. RRSET contained only unknown algorithms.
4.3. Extended DNS Error Code 2 - Unsupported DS Algorithm 3.3. Extended DNS Error Code 2 - Unsupported DS Algorithm
The resolver attempted to perform DNSSEC validation, but a DS RRSET The resolver attempted to perform DNSSEC validation, but a DS RRSET
contained only unknown algorithms. contained only unknown algorithms.
4.4. Extended DNS Error Code 3 - Stale Answer 3.4. Extended DNS Error Code 3 - Stale Answer
The resolver was unable to resolve answer within its time limits and The resolver was unable to resolve answer within its time limits and
decided to answer with a previously cached data instead of answering decided to answer with previously cached data instead of answering
with an error. This is typically caused by problems on authoritative with an error. This is typically caused by problems communicating
side, possibly as result of a DoS attack. with an authoritative serever, possibly as result of a DoS attack
against another network.
4.5. Extended DNS Error Code 4 - Forged Answer 3.5. Extended DNS Error Code 4 - Forged Answer
For policy reasons (legal obligation, or malware filtering, for For policy reasons (legal obligation, or malware filtering, for
instance), an answer was forged. instance), an answer was forged.
4.6. Extended DNS Error Code 5 - DNSSEC Indeterminate 3.6. Extended DNS Error Code 5 - DNSSEC Indeterminate
The resolver attempted to perform DNSSEC validation, but validation The resolver attempted to perform DNSSEC validation, but validation
ended in the Indeterminate state. ended in the Indeterminate state.
4.7. Extended DNS Error Code 6 - DNSSEC Bogus 3.7. Extended DNS Error Code 6 - DNSSEC Bogus
The resolver attempted to perform DNSSEC validation, but validation The resolver attempted to perform DNSSEC validation, but validation
ended in the Bogus state. ended in the Bogus state.
4.8. Extended DNS Error Code 7 - Signature Expired 3.8. Extended DNS Error Code 7 - Signature Expired
The resolver attempted to perform DNSSEC validation, a signature in The resolver attempted to perform DNSSEC validation, but a signature
the validation chain was expired. in the validation chain was expired.
4.9. Extended DNS Error Code 8 - Signature Not Yet Valid 3.9. Extended DNS Error Code 8 - Signature Not Yet Valid
The resolver attempted to perform DNSSEC validation, but the The resolver attempted to perform DNSSEC validation, but the
signatures received were not yet valid. signatures received were not yet valid.
4.10. Extended DNS Error Code 9 - DNSKEY Missing 3.10. Extended DNS Error Code 9 - DNSKEY Missing
A DS record existed at a parent, but no supported matching DNSKEY A DS record existed at a parent, but no supported matching DNSKEY
record could be found for the child. record could be found for the child.
4.11. Extended DNS Error Code 10 - RRSIGs Missing 3.11. Extended DNS Error Code 10 - RRSIGs Missing
The resolver attempted to perform DNSSEC validation, but no RRSIGs The resolver attempted to perform DNSSEC validation, but no RRSIGs
could be found for at least one RRset where RRSIGs were expected. could be found for at least one RRset where RRSIGs were expected.
4.12. Extended DNS Error Code 11 - No Zone Key Bit Set 3.12. Extended DNS Error Code 11 - No Zone Key Bit Set
The resolver attempted to perform DNSSEC validation, but no Zone Key The resolver attempted to perform DNSSEC validation, but no Zone Key
Bit was set in a DNSKEY. Bit was set in a DNSKEY.
4.13. Extended DNS Error Code 12 - NSEC Missing 3.13. Extended DNS Error Code 12 - NSEC Missing
The resolver attempted to perform DNSSEC validation, but the The resolver attempted to perform DNSSEC validation, but the
requested data was missing and a covering NSEC or NSEC3 was not requested data was missing and a covering NSEC or NSEC3 was not
provided. provided.
4.14. Extended DNS Error Code 13 - Cached Error 3.14. Extended DNS Error Code 13 - Cached Error
The resolver has cached SERVFAIL for this query without additional The resolver has cached SERVFAIL for this query.
information.
4.15. Extended DNS Error Code 14 - Not Ready 3.15. Extended DNS Error Code 14 - Not Ready
The server is unable to answer the query as it is not fully up and The server is unable to answer the query as it is not fully
functional yet. functional (yet).
4.16. Extended DNS Error Code 15 - Blocked 3.16. Extended DNS Error Code 15 - Blocked
The resolver attempted to perfom a DNS query but the domain is The resolver attempted to perfom a DNS query but the domain is
blacklisted due to a security policy implemented on the server being blacklisted due to a security policy implemented on the server being
directly talked to. directly talked to.
4.17. Extended DNS Error Code 16 - Censored 3.17. Extended DNS Error Code 16 - Censored
The resolver attempted to perfom a DNS query but the domain was The resolver attempted to perfom a DNS query but the domain was
blacklisted by a security policy imposed upon the server being talked blacklisted by a security policy imposed upon the server being talked
to. Note that how the imposed policy is applied is irrelevant (in- to. Note that how the imposed policy is applied is irrelevant (in-
band DNS somehow, court order, etc). band DNS filtering, court order, etc).
4.18. Extended DNS Error Code 17 - Prohibited 3.18. Extended DNS Error Code 17 - Prohibited
An authoritative or recursive resolver that receives a query from an An authoritative or recursive resolver that receives a query from an
"unauthorized" client can annotate its REFUSED message with this "unauthorized" client can annotate its REFUSED message with this
code. Examples of "unauthorized" clients are recursive queries from code. Examples of "unauthorized" clients are recursive queries from
IP addresses outside the network, blacklisted IP addresses, local IP addresses outside the network, blacklisted IP addresses, local
policy, etc. policy, etc.
4.19. Extended DNS Error Code 18 - Stale Answer 3.19. Extended DNS Error Code 18 - Filtered
The resolver was unable to resolve answer within its time limits and An authoritative or recursive resolver that receives a query from a
decided to answer with a previously cached NXDOMAIN answer instead of client that had requested certain domains be filtered can annotate
answering with an error. This is typically caused by problems on its REFUSED message with this code. Functionally, this amounts to
authoritative side, possibly as result of a DoS attack. "you requested that we filter domains like this one."
4.20. Extended DNS Error Code 19 - Lame 3.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer
The resolver was unable to resolve an answer within its configured
time limits and decided to answer with a previously cached NXDOMAIN
answer instead of answering with an error. This is typically caused
by problems communicating with an authoritative serever, possibly as
result of a DoS attack against another network.
3.21. Extended DNS Error Code 20 - Lame
An authoritative server that receives a query (with the RD bit clear) An authoritative server that receives a query (with the RD bit clear)
for a domain for which it is not authoritative SHOULD include this for a domain for which it is not authoritative SHOULD include this
EDE code in the SERVFAIL response. A resolver that receives a query EDE code in the SERVFAIL response. A resolver that receives a query
(with the RD bit clear) SHOULD include this EDE code in the REFUSED (with the RD bit clear) SHOULD include this EDE code in the REFUSED
response. response.
4.21. Extended DNS Error Code 20 - Deprecated 3.22. Extended DNS Error Code 21 - Deprecated
The requested operation or query is not supported as its use has been The requested operation or query is not supported as its use has been
deprecated. deprecated.
4.22. Extended DNS Error Code 21 - No Reachable Authority 3.23. Extended DNS Error Code 22 - No Reachable Authority
The resolver could not reach any of the authoritative name servers The resolver could not reach any of the authoritative name servers
(or they refused to reply). (or they refused to reply).
5. IANA Considerations 3.24. Extended DNS Error Code 23 - Network Error
5.1. A New Extended Error Code EDNS Option An unrecoverable error occurred while communicating with another
server.
4. IANA Considerations
4.1. A New Extended DNS Error Code EDNS Option
This document defines a new EDNS(0) option, entitled "Extended DNS This document defines a new EDNS(0) option, entitled "Extended DNS
Error", assigned a value of TBD1 from the "DNS EDNS0 Option Codes Error", assigned a value of TBD1 from the "DNS EDNS0 Option Codes
(OPT)" registry [to be removed upon publication: (OPT)" registry [to be removed upon publication:
[http://www.iana.org/assignments/dns-parameters/dns- [http://www.iana.org/assignments/dns-parameters/dns-
parameters.xhtml#dns-parameters-11] parameters.xhtml#dns-parameters-11]
Value Name Status Reference Value Name Status Reference
----- ---------------- ------ ------------------ ----- ---------------- ------ ------------------
TBD Extended DNS Error TBD [ This document ] TBD Extended DNS Error TBD [ This document ]
5.2. New Double-Index Registry Table for Extended Error Codes 4.2. New Registry Table for Extended DNS Error Codes
This document defines a new double-index IANA registry table, where This document defines a new IANA registry table, where the index
the index value is the INFO-CODE from the Extended DNS Error EDNS value is the INFO-CODE from the "Extended DNS Error" EDNS option
option defined in this document. The IANA is requested to create and defined in this document. The IANA is requested to create and
maintain this "Extended DNS Error codes" registry. The code-point maintain this "Extended DNS Error" codes registry. The code-point
space for each INFO-CODE index is to be broken into 3 ranges: space for the INFO-CODE index is to be broken into 3 ranges:
o 0 - 32767: Specification required. o 0 - 32767: Expert Review [RFC2434].
o 32768 - 49151: First come, first served. o 32768 - 49151: First come, first served.
o 49152 - 65535: Experimental / Private use o 49152 - 65535: Experimental / Private use.
A starting set of entries, based on the contents of this document, is A starting set of entries, based on the contents of this document, is
as follows: as follows:
INFO-CODE: 0 INFO-CODE: 0
Purpose: Other Error Purpose: Other Error
Reference: Section 4.1 Reference: Section 3.1
INFO-CODE: 1 INFO-CODE: 1
Purpose: Unsupported DNSKEY Algorithm Purpose: Unsupported DNSKEY Algorithm
Reference: Section 4.2 Reference: Section 3.2
INFO-CODE: 2 INFO-CODE: 2
Purpose: Unsupported DS Algorithm Purpose: Unsupported DS Algorithm
Reference: Section 4.3 Reference: Section 3.3
INFO-CODE: 3 INFO-CODE: 3
Purpose: Answering with stale/cached data Purpose: Stale Answer
Reference: Section 4.4 Reference: Section 3.4
INFO-CODE: 4 INFO-CODE: 4
Purpose: Forged Answer Purpose: Forged Answer
Reference: Section 4.5 Reference: Section 3.5
INFO-CODE: 5 INFO-CODE: 5
Purpose: DNSSEC Indeterminate Purpose: DNSSEC Indeterminate
Reference: Section 4.6 Reference: Section 3.6
INFO-CODE: 6 INFO-CODE: 6
Purpose: DNSSEC Bogus Purpose: DNSSEC Bogus
Reference: Section 4.7 Reference: Section 3.7
INFO-CODE: 7 INFO-CODE: 7
Purpose: Signature Expired Purpose: Signature Expired
Reference: Section 4.8 Reference: Section 3.8
INFO-CODE: 8 INFO-CODE: 8
Purpose: Signature Not Yet Valid Purpose: Signature Not Yet Valid
Reference: Section 4.9 Reference: Section 3.9
INFO-CODE: 9 INFO-CODE: 9
Purpose: DNSKEY Missing Purpose: DNSKEY Missing
Reference: Section 4.10 Reference: Section 3.10
INFO-CODE: 10 INFO-CODE: 10
Purpose: RRSIGs Missing Purpose: RRSIGs Missing
Reference: Section 4.11 Reference: Section 3.11
INFO-CODE: 11 INFO-CODE: 11
Purpose: No Zone Key Bit Set Purpose: No Zone Key Bit Set
Reference: Section 4.12 Reference: Section 3.12
INFO-CODE: 12 INFO-CODE: 12
Purpose: No NSEC records could be obtained Purpose: NSEC Missing
Reference: Section 4.13 Reference: Section 3.13
INFO-CODE: 13 INFO-CODE: 13
Purpose: The SERVFAIL error comes from the cache Purpose: Cached Error
Reference: Section 4.14 Reference: Section 3.14
INFO-CODE: 14 INFO-CODE: 14
Purpose: Not Ready. Purpose: Not Ready.
Reference: Section 4.15 Reference: Section 3.15
INFO-CODE: 15 INFO-CODE: 15
Purpose: Blocked Purpose: Blocked
Reference: Section 4.16 Reference: Section 3.16
INFO-CODE: 16 INFO-CODE: 16
Purpose: Censored Purpose: Censored
Reference: Section 4.17 Reference: Section 3.17
INFO-CODE: 17 INFO-CODE: 17
Purpose: Prohibited Purpose: Prohibited
Reference: Section 4.18 Reference: Section 3.18
INFO-CODE: 18 INFO-CODE: 18
Purpose: Answering with stale/cached NXDOMAIN data Purpose: Filtered
Reference: Section 4.19 Reference: Section 3.19
INFO-CODE: 19 INFO-CODE: 19
Purpose: Lame Purpose: Stale NXDomain Answer
Reference: Section 4.20 Reference: Section 3.20
INFO-CODE: 20 INFO-CODE: 20
Purpose: Deprecated Purpose: Lame
Reference: Section 4.21 Reference: Section 3.21
INFO-CODE: 21 INFO-CODE: 21
Purpose: Deprecated
Reference: Section 3.22
INFO-CODE: 22
Purpose: No Reachable Authority Purpose: No Reachable Authority
Reference: Section 4.21 Reference: Section 3.23
6. Security Considerations INFO-CODE: 23
Purpose: Network Error
Reference: Section 3.24
5. Security Considerations
Though DNSSEC continues to be deployed, unfortunately a significant Though DNSSEC continues to be deployed, unfortunately a significant
number of clients (~11% according to [GeoffValidation]) that receive number of clients (~11% according to [GeoffValidation]) that receive
a SERVFAIL from a validating resolver because of a DNSSEC validaion a SERVFAIL from a validating resolver because of a DNSSEC validaion
issue will simply ask the next (potentially non-validating) resolver issue will simply ask the next (potentially non-validating) resolver
in their list, and thus don't get any of the protections which DNSSEC in their list, and thus don't get any of the protections which DNSSEC
should provide. This is very similar to a kid asking his mother if should provide.
he can have another cookie. When the mother says "No, it will ruin
your dinner!", going off and asking his (more permissive) father and
getting a "Yes, sure, have a cookie!".
This information is unauthenticated information, and an attacker (e.g This information is unauthenticated information, and an attacker (e.g
MITM or malicious recursive server) could insert an extended error a MITM or malicious recursive server) could insert an extended error
response into already untrusted data -- ideally clients and resolvers response into already untrusted data -- ideally clients and resolvers
would not trust any unauthenticated information, but until we live in would not trust any unauthenticated information, but until we live in
an era where all DNS answers are authenticated via DNSSEC or other an era where all DNS answers are authenticated via DNSSEC or other
mechanisms, there are some tradeoffs. As an example, an attacker who mechanisms [RFC2845] [RFC8094], there are some tradeoffs. As an
is able to insert the DNSSEC Bogus Extended Error into a packet could example, an attacker who is able to insert the DNSSEC Bogus Extended
instead simply reply with a fictitious address (A or AAAA) record. Error into a packet could instead simply reply with a fictitious
address (A or AAAA) record.
7. Acknowledgements 6. Acknowledgements
The authors wish to thank Joe Abley, Mark Andrews, Stephane The authors wish to thank Joe Abley, Mark Andrews, Vittorio Bertola,
Bortzmeyer, Vladimir Cunat, Ralph Dolmans, Peter DeVries, Peter van Stephane Bortzmeyer, Vladimir Cunat, Ralph Dolmans, Peter DeVries,
Dijk, Donald Eastlake, Bob Harold, Geoff Huston, Shane Kerr, Edward Peter van Dijk, Donald Eastlake, Bob Harold, Paul Hoffman, Geoff
Lewis, Carlos M. Martinez, George Michelson, Michael Sheldon, Puneet Huston, Shane Kerr, Edward Lewis, Carlos M. Martinez, George
Sood, Petr Spacek, Ondrej Sury, Loganaden Velvindron, and Paul Vixie. Michelson, Michael Sheldon, Puneet Sood, Petr Spacek, Ondrej Sury,
They also vaguely remember discussing this with a number of people Loganaden Velvindron, and Paul Vixie. They also vaguely remember
over the years, but have forgotten who all they were -- if you were discussing this with a number of people over the years, but have
one of them, and are not listed, please let us know and we'll forgotten who all they were -- if you were one of them, and are not
acknowledge you. listed, please let us know and we'll acknowledge you.
I also want to thank the band "Infected Mushroom" for providing a One author also wants to thank the band "Infected Mushroom" for
good background soundtrack (and to see if I can get away with this!) providing a good background soundtrack (and to see if he can get away
Another author would like to thank the band "Mushroom Infectors". with this in an RFC!) Another author would like to thank the band
This was funny at the time we wrote it, but we cannot remember why... "Mushroom Infectors". This was funny at the time we wrote it, but we
cannot remember why...
8. References 7. References
8.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, <https://www.rfc- DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
editor.org/info/rfc2119>. editor.org/info/rfc2119>.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 2434,
DOI 10.17487/RFC2434, October 1998, <https://www.rfc-
editor.org/info/rfc2434>.
[RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", [RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)",
RFC 2671, DOI 10.17487/RFC2671, August 1999, RFC 2671, DOI 10.17487/RFC2671, August 1999,
<https://www.rfc-editor.org/info/rfc2671>. <https://www.rfc-editor.org/info/rfc2671>.
[RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms
for DNS (EDNS(0))", STD 75, RFC 6891, for DNS (EDNS(0))", STD 75, RFC 6891,
DOI 10.17487/RFC6891, April 2013, <https://www.rfc- DOI 10.17487/RFC6891, April 2013, <https://www.rfc-
editor.org/info/rfc6891>. editor.org/info/rfc6891>.
8.2. Informative References 7.2. Informative References
[GeoffValidation] [GeoffValidation]
IANA, "A quick review of DNSSEC Validation in today's IANA, "A quick review of DNSSEC Validation in today's
Internet", June 2016, <http://www.potaroo.net/ Internet", June 2016, <http://www.potaroo.net/
presentations/2016-06-27-dnssec.pdf>. presentations/2016-06-27-dnssec.pdf>.
[RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
Wellington, "Secret Key Transaction Authentication for DNS Wellington, "Secret Key Transaction Authentication for DNS
(TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000,
<https://www.rfc-editor.org/info/rfc2845>. <https://www.rfc-editor.org/info/rfc2845>.
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