draft-ietf-dnsop-extended-error-02.txt   draft-ietf-dnsop-extended-error-03.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: March 25, 2019 ISC Expires: June 23, 2019 ISC
R. Arends R. Arends
ICANN ICANN
W. Hardaker W. Hardaker
USC/ISI USC/ISI
D. Lawrence D. Lawrence
Oracle + Dyn Oracle + Dyn
September 21, 2018 December 20, 2018
Extended DNS Errors Extended DNS Errors
draft-ietf-dnsop-extended-error-02 draft-ietf-dnsop-extended-error-03
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. The primary use case is 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. of DNS and DNSSEC failures, the Extended DNS Errors option defined in
this document allows all response types to contain extended error
information.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 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 March 25, 2019. This Internet-Draft will expire on June 23, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction and background . . . . . . . . . . . . . . . . . 2 1. Introduction and background . . . . . . . . . . . . . . . . . 3
1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3
2. Extended Error EDNS0 option format . . . . . . . . . . . . . 3 2. Extended Error EDNS0 option format . . . . . . . . . . . . . 3
3. Use of the Extended DNS Error option . . . . . . . . . . . . 5 3. Use of the Extended DNS Error option . . . . . . . . . . . . 4
3.1. The R (Retry) flag . . . . . . . . . . . . . . . . . . . 5
3.2. The RESPONSE-CODE field . . . . . . . . . . . . . . . . . 5
3.3. The INFO-CODE field . . . . . . . . . . . . . . . . . . . 5
3.4. The EXTRA-TEXT field . . . . . . . . . . . . . . . . . . 5
4. Defined Extended DNS Errors . . . . . . . . . . . . . . . . . 5 4. Defined Extended DNS Errors . . . . . . . . . . . . . . . . . 5
4.1. SERVFAIL(2) extended information codes . . . . . . . . . 5 4.1. INFO-CODEs for use with RESPONSE-CODE: SERVFAIL(2) . . . 6
4.1.1. Extended DNS Error Code 1 - DNSSEC Bogus . . . . . . 6 4.1.1. SERVFAIL Extended DNS Error Code 1 - DNSSEC Bogus . . 6
4.1.2. Extended DNS Error Code 2 - DNSSEC Indeterminate . . 6 4.1.2. SERVFAIL Extended DNS Error Code 2 - DNSSEC
4.1.3. Extended DNS Error Code 3 - Signature Expired . . . . 6 Indeterminate . . . . . . . . . . . . . . . . . . . . 6
4.1.4. Extended DNS Error Code 4 - Signature Not Yet Valid . 6 4.1.3. SERVFAIL Extended DNS Error Code 3 - Signature
4.1.5. Extended DNS Error Code 5 - Unsupported Expired . . . . . . . . . . . . . . . . . . . . . . . 6
4.1.4. SERVFAIL Extended DNS Error Code 4 - Signature Not
Yet Valid . . . . . . . . . . . . . . . . . . . . . . 6
4.1.5. SERVFAIL Extended DNS Error Code 5 - Unsupported
DNSKEY Algorithm . . . . . . . . . . . . . . . . . . 6 DNSKEY Algorithm . . . . . . . . . . . . . . . . . . 6
4.1.6. Extended DNS Error Code 6 - Unsupported 4.1.6. SERVFAIL Extended DNS Error Code 6 - Unsupported
DS Algorithm . . . . . . . . . . . . . . . . . . . . 6 DS Algorithm . . . . . . . . . . . . . . . . . . . . 6
4.1.7. Extended DNS Error Code 7 - DNSKEY missing . . . . . 6 4.1.7. SERVFAIL Extended DNS Error Code 7 - DNSKEY missing . 6
4.1.8. Extended DNS Error Code 8 - RRSIGs missing . . . . . 6 4.1.8. SERVFAIL Extended DNS Error Code 8 - RRSIGs missing . 7
4.1.9. Extended DNS Error Code 9 - No Zone Key Bit Set . . . 6 4.1.9. SERVFAIL Extended DNS Error Code 9 - No Zone Key Bit
4.2. REFUSED(5) extended information codes . . . . . . . . . . 7 Set . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2.1. Extended DNS Error Code 1 - Lame . . . . . . . . . . 7 4.2. INFO-CODEs for use with RESPONSE-CODE: REFUSED(5) . . . . 7
4.2.2. Extended DNS Error Code 2 - Prohibited . . . . . . . 7 4.2.1. REFUSED Extended DNS Error Code 1 - Lame . . . . . . 7
4.3. NXDOMAIN(3) extended information codes . . . . . . . . . 7 4.2.2. REFUSED Extended DNS Error Code 2 - Prohibited . . . 7
4.3.1. Extended DNS Error Code 1 - Blocked . . . . . . . . . 7 4.3. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3) . . . 7
4.3.1. NXDOMAIN Extended DNS Error Code 1 - Blocked . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5.1. new Extended Error Code EDNS Option . . . . . . . . . . . 7 5.1. new Extended Error Code EDNS Option . . . . . . . . . . . 7
5.2. new Extended Error Code EDNS Option . . . . . . . . . . . 7 5.2. New Extended Error Code EDNS Option . . . . . . . . . . . 8
6. Open questions . . . . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 8.1. Normative References . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . 9 8.2. Informative References . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . 9 Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 11
Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
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 the answer was marked REFUSED because of a lame delegation, or - e.g. was the answer marked REFUSED because of a lame delegation, or
because of a lame delegation or because the nameserver is still because the nameserver is still starting up and loading zones? Is a
starting up and loading zones? Is a SERVFAIL a DNSSEC validation SERVFAIL a DNSSEC validation issue, or is the nameserver experiencing
issue, or is the nameserver experiencing a bad hair day? a bad hair day?
A good example of issues that would benefit by additional error A good example of issues that would benefit by additional error
information is an error caused by a DNSSEC validation issue. 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 DNSSEC bogus name (using a validating
resolver), the stub resolver receives only a SERVFAIL in response. resolver), the stub resolver receives only a SERVFAIL in response.
Unfortunately, SERVFAIL is used to signal many sorts of DNS errors, Unfortunately, SERVFAIL is used to signal many sorts of DNS errors,
and so the stub resolver simply asks the next configured DNS and so the stub resolver simply asks the next configured DNS
resolver. The result of trying the next resolver is one of two resolver. The result of trying the next resolver is one of two
outcomes: either the next resolver also validates, a SERVFAIL is outcomes: either the next resolver also validates, a SERVFAIL is
returned again, and the user gets an (largely) incomprehensible error returned again, and the user gets an (largely) incomprehensible error
message; or the next resolver is not a validating resolver, and the message; or the next resolver is not a validating resolver, and the
user is returned a potentially harmful result. user is returned a potentially harmful result.
This document specifies a mechanism to extend (or annotate) DNS This document specifies a mechanism to extend (or annotate) DNS
errors to provide additional information about the cause of the errors to provide additional information about the cause of the
error. This information can be used by the resolver to make a error. When properly authenticated, this information can be used by
decision regarding whether or not to retry, or by technical users the resolver to make a decision regarding whether or not to retry or
attempting to debug issues. it can be used or by technical users attempting to debug issues.
Here is a reference to an "external" (non-RFC / draft) thing:
([IANA.AS_Numbers]). And this is a link to an
ID:[I-D.ietf-sidr-iana-objects].
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 error This draft uses an EDNS0 ([RFC2671]) option to include Extended DNS
(ExtError) information in DNS messages. The option is structured as Error (EDE) information in DNS messages. The option is structured as
follows: follows:
1 1 1 1 1 1 1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
0: | OPTION-CODE | 0: | OPTION-CODE |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
2: | OPTION-LENGTH | 2: | OPTION-LENGTH |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
4: | R | RESERVED | 4: | R | RESERVED |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
6: | RESPONSE-CODE | 6: | RESPONSE-CODE | INFO-CODE |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
8: | INFO-CODE |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
A: | EXTRA-TEXT | 8: | EXTRA-TEXT |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
o OPTION-CODE, 2 octets (defined in [RFC6891]), for ExtError is TBD. Field definition details:
o OPTION-CODE, 2 octets (defined in [RFC6891]), for EDE is TBD.
[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. and should be 4 plus the length of the EXTRA-TEXT section (which
may be a zero-length string).
o The RETRY flag, 1 bit; the RETRY bit (R) indicates a flag defined
for use in this specification.
o The RESERVED bits, 15 bits: these bits are reserved for future
use, potentially as additional flags. The RESERVED bits MUST be
set to 0 by the sender and SHOULD be ignored by the receiver.
o RESPONSE-CODE, 4 bits.
o INFO-CODE, 12-bits.
o EXTRA-TEXT, a variable length, ASCII encoded, text field that may
hold additional textual information.
o RESERVED, 2 octets; the first bit (R) indicates a flag defined in 3. Use of the Extended DNS Error option
this specification. The remaining bits are reserved for future
use, potentially as additional flags.
o RESPONSE-CODE, 2 octets: this SHOULD be a copy of the RCODE from The Extended DNS Error (EDE) is an EDNS option. It can be included
the primary DNS packet. When including multiple extended error in any response (SERVFAIL, NXDOMAIN, REFUSED, etc) to a query that
EDNS0 records in a response in order to provide additional error includes an EDNS option. This document includes a set of initial
information, the RESPONSE-CODE MAY be a different RCODE. codepoints (and requests to the IANA to add them to the registry),
but is extensible via the IANA registry to allow additional error and
information codes to be defined in the future.
o INFO-CODE, 2 octets. The fields of the Extended DNS Error option are defined further in
the following sub-sections.
o A variable length EXTRA-TEXT field holding additional textual 3.1. The R (Retry) flag
information. It may be zero length when no additional textual
information is included.
Currently the only defined flag is the R flag. The R (Retry) flag provides a hint as to what the receiver may want
to do with this annotated error. Specifically, the R (or Retry) flag
provides a hint to the receiver that it should retry the query to
another server. If the R bit is set (1), the sender believes that
retrying the query may provide a successful answer next time; if the
R bit is clear (0), the sender believes that the resolver should not
ask another server.
R - Retry The R (or Retry) flag provides a hint to the receiver that The mechanism is specifically designed to be extensible, and so
it should retry the query, probably by querying another server. implementations may receive EDE codes that it does not understand.
If the R bit is set (1), the sender believes that retrying the The R flag allows implementations to make a decision as to what to do
query may provide a successful answer next time; if the R bit is if it receives a response with an unknown code - retry or drop the
clear (0), the sender believes that it should not ask another query. Note that this flag is only a suggestion. Unless a
server. protective transport mechanism (like TSIG [RFC2845] or TLS [RFC8094])
is used, the bit's value could have have been altered by a person-in-
the-middle. Receivers can choose to ignore this hint. See the
security considerations for additional considerations.
The remaining bits in the RESERVED field are reserved for future use 3.2. The RESPONSE-CODE field
and MUST be set to 0 by the sender and SHOULD be ignored by the
receiver.
INFO-CODE: A code point that, when combined with the RCODE from the This 4-bit value SHOULD be a copy of the RCODE from the primary DNS
DNS packet, serve as a joint-index into the IANA "Extended DNS packet. Multiple EDNS0/EDE records may be included in the response.
Errors" registry. When including multiple EDNS0/EDE records in a response in order to
provide additional error information, other RESPONSE-CODEs MAY use a
different RCODE.
3. Use of the Extended DNS Error option 3.3. The INFO-CODE field
The Extended DNS Error (EDE) is an EDNS option. It can be included This 12-bit value provides the additional context for the RESPONSE-
in any error response (SERVFAIL, NXDOMAIN, REFUSED, etc) to a query CODE value. This combination of the RESPONSE-CODE and the INFO-CODE
that includes an EDNS option. This document includes a set of serve as a joint-index into the IANA "Extended DNS Errors" registry.
initial codepoints (and requests to the IANA to add them to the
registry), but is extensible via the IANA registry to allow
additional error and information codes to be defined in the future.
The R (Retry) flag provides a hint (or suggestion) as to what the 3.4. The EXTRA-TEXT field
receiver may want to do with this annotated error. The mechanism is
specifically designed to be extensible, and so implementations may
receive EDE codes that it does not understand. The R flag allows
implementations to make a decision as to what to do if it receives a
response with an unknown code - retry or drop the query. Note that
this flag is only a suggestion or hint. Receivers can choose to
ignore this hint.
The EXTRA-INFO textual field may be zero-length, or may hold The ASCII-encoded, EXTRA-TEXT field may be zero-length, or may hold
additional information useful to network operators. additional information useful to network operators.
4. Defined Extended DNS Errors 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 codepoints will be intended to be extensible, and additional code-points can be
registered in the "Extended DNS Errors" registry. This document registered in the "Extended DNS Errors" registry. This document
provides suggestions for the R flag, but the originating server may provides suggestions for the R flag, but the originating server may
ignore these recommendations if it knows better. ignore these recommendations if it knows better.
The RESPONSE-CODE and the INFO-CODE from the EDE EDNS option is used The RESPONSE-CODE and the INFO-CODE from the EDE EDNS option is used
to serve as a double index into the "Extended DNS Error codes" IANA to serve as a double index into the "Extended DNS Error codes" IANA
registry, the initial values for which are defined in the following registry, the initial values for which are defined in the following
sub-sections. sub-sections.
4.1. SERVFAIL(2) extended information codes 4.1. INFO-CODEs for use with RESPONSE-CODE: SERVFAIL(2)
4.1.1. Extended DNS Error Code 1 - DNSSEC Bogus
4.1.1. SERVFAIL Extended DNS Error Code 1 - 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. The R flag should not be set. ended in the Bogus state. The R flag should not be set.
4.1.2. Extended DNS Error Code 2 - DNSSEC Indeterminate 4.1.2. SERVFAIL Extended DNS Error Code 2 - 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. The R flag should not be set. ended in the Indeterminate state. The R flag should not be set.
4.1.3. Extended DNS Error Code 3 - Signature Expired 4.1.3. SERVFAIL Extended DNS Error Code 3 - Signature Expired
The resolver attempted to perform DNSSEC validation, but the The resolver attempted to perform DNSSEC validation, but the
signature was expired. The R flag should not be set. signature was expired. The R flag should not be set.
4.1.4. Extended DNS Error Code 4 - Signature Not Yet Valid 4.1.4. SERVFAIL Extended DNS Error Code 4 - 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. The R flag should not be signatures received were not yet valid. The R flag should not be
set. set.
4.1.5. Extended DNS Error Code 5 - Unsupported DNSKEY Algorithm 4.1.5. SERVFAIL Extended DNS Error Code 5 - 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. The R flag should not be RRSET contained only unknown algorithms. The R flag should be set.
set.
4.1.6. Extended DNS Error Code 6 - Unsupported DS Algorithm 4.1.6. SERVFAIL Extended DNS Error Code 6 - 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. The R flag should not be set. contained only unknown algorithms. The R flag should be set.
4.1.7. Extended DNS Error Code 7 - DNSKEY missing 4.1.7. SERVFAIL Extended DNS Error Code 7 - DNSKEY missing
A DS record existed at a parent, but no DNSKEY record could be found A DS record existed at a parent, but no DNSKEY record could be found
for the child. The R flag should not be set. for the child. The R flag should not be set.
4.1.8. Extended DNS Error Code 8 - RRSIGs missing 4.1.8. SERVFAIL Extended DNS Error Code 8 - 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.
4.1.9. Extended DNS Error Code 9 - No Zone Key Bit Set 4.1.9. SERVFAIL Extended DNS Error Code 9 - 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.
4.2. REFUSED(5) extended information codes 4.2. INFO-CODEs for use with RESPONSE-CODE: REFUSED(5)
4.2.1. Extended DNS Error Code 1 - Lame 4.2.1. REFUSED Extended DNS Error Code 1 - Lame
An authoritative resolver that receives a query (with the RD bit An authoritative resolver that receives a query (with the RD bit
clear) for a domain for which it is not authoritative SHOULD include clear) for a domain for which it is not authoritative SHOULD include
this EDE code in the REFUSED response. Implementations should set this EDE code in the REFUSED response. Implementations should set
the R flag in this case (another nameserver might not be lame). the R flag in this case (another nameserver might not be lame).
4.2.2. Extended DNS Error Code 2 - Prohibited 4.2.2. REFUSED Extended DNS Error Code 2 - 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.
Implementations SHOULD allow operators to define what to set the R Implementations SHOULD allow operators to define what to set the R
flag to in this case. flag to in this case.
4.3. NXDOMAIN(3) extended information codes 4.3. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3)
4.3.1. Extended DNS Error Code 1 - Blocked 4.3.1. NXDOMAIN Extended DNS Error Code 1 - 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. The R flag should not be set. blacklisted due to a security policy. The R flag should not be set.
5. IANA Considerations 5. IANA Considerations
[This section under construction, beware. ]
5.1. new Extended Error Code EDNS Option 5.1. new Extended 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 Extended Error Code EDNS Option 5.2. New Extended Error Code EDNS Option
This document defines a new double-index IANA registry table, where This document defines a new double-index IANA registry table, where
the first index value is the RCODE value and the second index value the first index value is the RCODE value and the second index value
is the INFO-CODE from the Extended DNS Error EDNS option defined in is the INFO-CODE from the Extended DNS Error EDNS option defined in
this document. The IANA is requested to create and maintain this this document. The IANA is requested to create and maintain this
"Extended DNS Error codes" registry. The codepoint space for each "Extended DNS Error codes" registry. The codepoint space for each
RCODE index is to be broken into 3 ranges: INFO-CODE index is to be broken into 3 ranges:
o 1 - 16384: Specification required. o 0 - 3583: Specification required.
o 3584 - 3839: First Come First Served.
o 3840 - 4095: Experimental / Private use
o 16385 - 65000: First Come First Served A starting set of entries, based on the contents of this document, is
as follows:
o 65000 - 65534: Experimental / Private use RESPONSE-CODE: 2 (SERVFAIL)
INFO-CODE: 1
Purpose: DNSSEC Bogus
Reference: Section 4.1.1
The codepoints 0, 65535 are reserved. RESPONSE-CODE: 2 (SERVFAIL)
INFO-CODE: 2
Purpose: DNSSEC Indeterminate
Reference: Section 4.1.2
A starting table, based on the contents of this document, is as RESPONSE-CODE: 2 (SERVFAIL)
follows: INFO-CODE: 3
Purpose: Signature Expired
Reference: Section 4.1.3
| RCODE | EDE-INFO-CODE | Meaning | Ref | RESPONSE-CODE: 2 (SERVFAIL)
|-------------+-------------------------+---------------------------------------------+------------------------------------------| INFO-CODE: 4
| SERVFAIL(2) | DNSSEC_BOGUS(1) | DNSSEC Validation resulted in Bogus | section <xref target="errbogus" /> | Purpose: Signature Not Yet Valid
| SERVFAIL(2) | DNSSEC_INDETERMINATE(2) | DNSSEC Validation resulted in Indeterminate | section <xref target="errindeterminate" /> | Reference: Section 4.1.4
[incomplete] RESPONSE-CODE: 2 (SERVFAIL)
INFO-CODE: 5
Purpose: Unsupported DNSKEY
Reference: Section 4.1.5
6. Open questions RESPONSE-CODE: 2 (SERVFAIL)
INFO-CODE: 6
Purpose: Unsupported DS Algorithm
Reference: Section 4.1.6
1 Can this be included in *any* response or only responses to RESPONSE-CODE: 2 (SERVFAIL)
requests that included an EDNS option? Resolvers are supposed to INFO-CODE: 7
ignore additional. EDNS capable ones are supposed to simply Purpose: DNSKEY missing
ignore unknown options. I know the spec says you can only include Reference: Section 4.1.7
EDNS0 in a response if in a request -- it is time to reevaluate
this?
7. Security Considerations RESPONSE-CODE: 2 (SERVFAIL)
INFO-CODE: 8
Purpose: RRSIGs missing
Reference: Section 4.1.8
DNSSEC is being deployed - unfortunately a significant number of RESPONSE-CODE: 2 (SERVFAIL)
clients (~11% according to [GeoffValidation]), when receiving a INFO-CODE: 9
SERVFAIL from a validating resolver because of a DNSSEC validaion Purpose: No Zone Key Bit Set
issue simply ask the next (non-validating) resolver in their list, Reference: Section 4.1.9
and don't get any of the protections which DNSSEC should provide.
This is very similar to a kid asking his mother if 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, cookie!".
8. Acknowledgements RESPONSE-CODE: 3 (NXDOMAIN)
INFO-CODE: 1
Purpose: Blocked
Reference: Section 4.3.1
The authors wish to thank Geoff Huston and Bob Harold, Carlos M. RESPONSE-CODE: 5 (REFUSED)
Martinez, Peter DeVries, George Michelson, Mark Andrews, Ondrej Sury, INFO-CODE: 1
Edward Lewis, Paul Vixie, Shane Kerr, Loganaden Velvindron. They Purpose: Lame
also vaguely remember discussing this with a number of people over Reference: Section 4.2.1
the years, but have forgotten who all they were -- if you were one of
RESPONSE-CODE: 5 (REFUSED)
INFO-CODE: 2
Purpose: Prohibited
Reference: Section 4.2.2
6. Security Considerations
Though DNSSEC continues to be deployed, unfortunately a significant
number of clients (~11% according to [GeoffValidation]) that receive
a SERVFAIL from a validating resolver because of a DNSSEC validaion
issue will simply ask the next (potentially non-validating) resolver
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
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
MITM or malicious recursive server) could insert an extended error
response into already untrusted data -- ideally clients and resolvers
would not trust any unauthenticated information, but until we live in
an era where all DNS answers are authenticated via DNSSEC or other
mechanisms, there are some tradeoffs. As an example, an attacker who
is able to insert the DNSSEC Bogus Extended Error into a packet could
instead simply reply with a fictitious address (A or AAAA) record.
The R bit hint and extended error information are informational -
implementations can choose how much to trust this information and
validating resolvers / stubs may choose to put a different weight on
it.
7. Acknowledgements
The authors wish to thank Joe Abley, Mark Andrews, Peter DeVries,
Peter van Dijk, Donald Eastlake, Bob Harold, Evan Hunt, Geoff Huston,
Shane Kerr, Edward Lewis, Carlos M. Martinez, George Michelson, Petr
Spacek, Ondrej Sury, Loganaden Velvindron, and Paul Vixie. They also
vaguely remember discussing this with a number of people over the
years, but have forgotten who all they were -- if you were one of
them, and are not listed, please let us know and we'll acknowledge them, and are not listed, please let us know and we'll acknowledge
you. you.
I also want to thank the band "Infected Mushroom" for providing a I also want to thank the band "Infected Mushroom" for providing a
good background soundtrack (and to see if I can get away with this!) good background soundtrack (and to see if I can get away with this!)
Another author would like to thank the band "Mushroom Infectors". Another author would like to thank the band "Mushroom Infectors".
This was funny at the time we wrote it, but I cannot remember why... This was funny at the time we wrote it, but I cannot remember why...
We would like to especially thank Peter van Dijk, who sent GitHub 8. References
pull requests.
9. References
9.1. Normative References
[IANA.AS_Numbers] 8.1. Normative References
IANA, "Autonomous System (AS) Numbers",
<http://www.iana.org/assignments/as-numbers>.
[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, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
<https://www.rfc-editor.org/info/rfc2119>. editor.org/info/rfc2119>.
9.2. Informative References 8.2. 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>.
[I-D.ietf-sidr-iana-objects] [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
Manderson, T., Vegoda, L., and S. Kent, "RPKI Objects Wellington, "Secret Key Transaction Authentication for DNS
issued by IANA", draft-ietf-sidr-iana-objects-03 (work in (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000,
progress), May 2011. <https://www.rfc-editor.org/info/rfc2845>.
[RFC8094] Reddy, T., Wing, D., and P. Patil, "DNS over Datagram
Transport Layer Security (DTLS)", RFC 8094,
DOI 10.17487/RFC8094, February 2017, <https://www.rfc-
editor.org/info/rfc8094>.
Appendix A. Changes / Author Notes. Appendix A. Changes / Author Notes.
[RFC Editor: Please remove this section before publication ] [RFC Editor: Please remove this section before publication ]
From -00 to -01: From -00 to -01:
o Address comments from IETF meeting. o Address comments from IETF meeting.
o document copying the response code o document copying the response code
o mention zero length fields are ok o mention zero length fields are ok
o clarify lookup procedure o clarify lookup procedure
o mention that table isn't done o mention that table isn't done
From -03 to -IETF 00: From -03 to -IETF 00:
o Renamed to draft-ietf-dnsop-extended-error o Renamed to draft-ietf-dnsop-extended-error
From -02 to -03: From -02 to -03:
o Added David Lawrence -- I somehow missed that in last version. o Added David Lawrence -- I somehow missed that in last version.
 End of changes. 79 change blocks. 
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