Internet DRAFT - draft-wing-dnsop-structured-dns-error-page
draft-wing-dnsop-structured-dns-error-page
DNSOP WG D. Wing
Internet-Draft Citrix
Updates: 8914 (if approved) T. Reddy
Intended status: Standards Track Nokia
Expires: 25 March 2023 N. Cook
Open-Xchange
M. Boucadair
Orange
21 September 2022
Structured Data for Filtered DNS
draft-wing-dnsop-structured-dns-error-page-05
Abstract
DNS filtering is widely deployed for network security, but filtered
DNS responses lack information for the end user to understand the
reason for the filtering. Existing mechanisms to provide detail to
end users cause harm especially if the blocked DNS response is to an
HTTPS website.
This document updates the EXTRA-TEXT field of Extended DNS Error to
provide details on the DNS filtering. This information can be parsed
by the client and displayed, logged, or used for other purposes.
This document updates RFC 8914.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 25 March 2023.
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Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Limitations of Filtering techniques . . . . . . . . . . . . . 4
4. I-JSON in EXTRA-TEXT field . . . . . . . . . . . . . . . . . 6
5. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 7
5.1. Client Generating Request . . . . . . . . . . . . . . . . 7
5.2. Server Generating Response . . . . . . . . . . . . . . . 7
5.3. Client Processing Response . . . . . . . . . . . . . . . 7
6. Interoperation with RPZ Servers . . . . . . . . . . . . . . . 9
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10
9. IANA Considerationsd . . . . . . . . . . . . . . . . . . . . 10
9.1. New registry for SubError Codes . . . . . . . . . . . . . 11
10. Initial Sub-errors . . . . . . . . . . . . . . . . . . . . . 12
11. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
12.1. Normative References . . . . . . . . . . . . . . . . . . 13
12.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
DNS filters are deployed for a variety of reasons including endpoint
security, parental filtering, and filtering required by law
enforcement. Network-based security solutions such as firewalls and
Intrusion Prevention Systems (IPS) rely upon network traffic
inspection to implement perimeter-based security policies and operate
by filtering DNS responses. In a home, DNS filtering is used for the
same reasons as above and additionally for parental control.
Internet Service Providers typically block access to some DNS domains
due to a requirement imposed by an external entity (e.g., law
enforcement agency) also performed using DNS-based content filtering.
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Users of DNS services which perform filtering may wish to receive
more information about such filtering to resolve problems with the
filter -- for example to contact the administrator to allowlist a
domain that was erroneously filtered or to understand the reason a
particular domain was filtered. With that information, the user can
choose another network, open a trouble ticket with the DNS
administrator to resolve erroneous filtering, log the information, or
other uses.
For both DNS filtering mechanisms described in Section 4 of
(Section 3), the DNS server can return extended error codes Blocked,
Censored, Filtered, or Forged Answer defined in Section 4 of
[RFC8914]. However, these codes only explain that filtering occurred
but lack detail for the user to diagnose erroneous filtering.
No matter which type of response is generated (forged IP address(es),
NXDOMAIN or empty answer, even with an extended error code), the user
who triggered the DNS query has little chance to understand which
entity filtered the query, how to report a mistake in the filter, or
why the entity filtered it at all. This document describes a
mechanism to provide such detail.
One of the other benefits of this approach is to eliminate the need
to "spoof" block pages for HTTPS resources. This is achieved since
clients implementing this approach would be able to display a
meaningful error message, and would not need to connect to such a
block page. This approach thus avoids the need to install a local
root certificate authority on those IT-managed devices.
This document describes a format for computer-parsable data in the
EXTRA-TEXT field of Extended DNS Errors [RFC8914].
This document does not recommend DNS filtering but provides a
mechanism for better transparency to explain to the users why some
DNS queries are filtered.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document uses terms defined in DNS Terminology [RFC8499].
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"Requestor" refers to the side that sends a request. "Responder"
refers to an authoritative, recursive resolver or other DNS component
that responds to questions. Other terminology is used here as
defined in the RFCs cited by this document.
"Encrypted DNS" refers to any encrypted scheme to convey DNS
messages, for example, DNS-over-HTTPS [RFC8484], DNS-over-TLS
[RFC7858], or DNS-over-QUIC [RFC9250].
3. Limitations of Filtering techniques
DNS responses can be filtered by sending a bogus (also called,
"forged") A or AAAA response, NXDOMAIN error or empty answer, or an
extended DNS error (EDE) code defined in [RFC8914]. Each of these
methods have advantages and disadvantages that are discussed below:
1. The DNS response is forged to provide a list of IP addresses that
points to an HTTP(S) server alerting the end user about the
reason for blocking access to the requested domain (e.g.,
malware). When an HTTP(S) enabled domain name is blocked, the
network security device (e.g., CPE, firewall) presents a block
page instead of the HTTP response from the content provider
hosting that domain. If an HTTP enabled domain name is blocked,
the network security device intercepts the HTTP request and
returns a block page over HTTP. If an HTTPS enabled domain is
blocked, the block page is also served over HTTPS. In order to
return a block page over HTTPS, man in the middle (MITM) is
enabled on endpoints by generating a local root certificate and
an accompanying (local) public/private key pair. The local root
certificate is installed on the endpoint while the network
security device(s) stores a copy of the private key. During the
TLS handshake, the network security device modifies the
certificate provided by the server and (re)signs it using the
private key from the local root certificate.
* However, configuring the local root certificate on endpoints
is not a viable option in several deployments like home
networks, schools, Small Office/Home Office (SOHO), and Small/
Medium Enterprise (SME). In these cases, the typical behavior
is that the filtered DNS response points to a server that will
display the block page. If the client is using HTTPS (via web
browser or another application) this results in a certificate
validation error which gives no information to the end-user
about the reason for the DNS filtering. Browsers will display
errors such as "The security certificate presented by this
website was not issued by a trusted certificate authority"
(Internet Explorer/Edge"), "The site's security certificate is
not trusted" (Chrome), "This Connection is Untrusted"
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(Firefox), "Safari can't verify the identity of the
website..." (Safari on MacOS). Applications might display
even more cryptic error messages.
* Enterprise networks do not assume that all the connected
devices are managed by the IT team or Mobile Device Management
(MDM) devices, especially in the quite common Bring Your Own
Device (BYOD) scenario. In addition, the local root
certificate cannot be installed on IoT devices without a
device management tool.
* An end user does not know why the connection was prevented
and, consequently, may repeatedly try to reach the domain but
with no success. Frustrated, the end user may switch to an
alternate network that offers no DNS filtering against malware
and phishing, potentially compromising both security and
privacy. Furthermore, certificate errors train users to click
through certificate errors, which is a bad security practice.
To eliminate the need for an end user to click through
certificate errors, an end user may manually install a local
root certificate on a host device. Doing so, however, is also
a bad security practice as it creates a security vulnerability
that may be exploited by a MITM attack. When a manually
installed local root certificate expires, the user has to
(again) manually install the new local root certificate.
2. The DNS response is forged to provide a NXDOMAIN response to
cause the DNS lookup to terminate in failure. In this case, an
end user does not know why the domain cannot be reached and may
repeatedly try to reach the domain but with no success.
Frustrated, the end user may use insecure connections to reach
the domain, potentially compromising both security and privacy.
3. The extended error codes Blocked, Censored, and Filtered defined
in Section 4 of [RFC8914] can be returned by a DNS server to
provide additional information about the cause of an DNS error.
If the extended error code "Forged Answer" defined in Section 4.5
of [RFC8914] is returned by the DNS server, the client can
identify the DNS response is forged together with the reason for
HTTPS certificate error.
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4. These extended error codes do not suffer from the limitations
discussed in bullets (1) and (2), but the user still does not
know the exact reason nor he/she is aware of the exact entity
blocking the access to the domain. For example, a DNS server may
block access to a domain based on the content category such as
"Malware" to protect the endpoint from malicious software,
"Phishing" to prevent the user from revealing sensitive
information to the attacker, etc. A user needs to know the
contact details of the IT/InfoSec team to raise a complaint.
5. When a resolver or forwarder forwards the received EDE option,
the EXTRA-TEXT field only conveys the source of the error
(Section 3 of [RFC8914]) and does not provide additional textual
information about the cause of the error.
4. I-JSON in EXTRA-TEXT field
Servers that are compliant with this specification send I-JSON data
in the EXTRA-TEXT field [RFC8914] using the Internet JSON (I-JSON)
message format [RFC7493].
| Note that [RFC7493] was based on [RFC7159], but [RFC7159] was
| replaced by [RFC8259].
This document defines the following JSON names:
c: (contact) The contact details of the IT/InfoSec team to report
mis-classified DNS filtering. This field is structured as an
array of contact URIs (e.g., tel, sips, https). At least one
contact URI MUST be included. This field is mandatory.
j: (justification) the textual justification for this particular DNS
filtering. The field should be treated only as diagnostic
information for IT staff. This field is mandatory.
s: (suberror) the suberror code for this particular DNS filtering.
This field is optional.
o: (organization) human-friendly name of the organization that
filtered this particular DNS query. This field is optional.
New JSON names MUST be defined in the IANA registry (Section 9),
consist only of lower-case ASCII characters, digits, and hyphens
(that is, Unicode characters U+0061 through 007A, U+0030 through
U+0039, and U+002D). These names MUST be 63 characters or shorter
and it is RECOMMENDED they be as short as possible.
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To reduce packet overhead the generated JSON SHOULD be as short as
possible: short domain names, concise text in the values for the "j"
and "o" names, and minified JSON (that is, without spaces or line
breaks between JSON elements).
The JSON data can be parsed to display to the user, logged, or
otherwise used to assist the end-user or IT staff with
troubleshooting and diagnosing the cause of the DNS filtering.
5. Protocol Operation
5.1. Client Generating Request
When generating a DNS query, the client includes the Extended DNS
Error option Section 2 of [RFC8914] in the OPT pseudo-RR [RFC6891] to
elicit the Extended DNS Error option in the DNS response.
5.2. Server Generating Response
When the DNS server filters its DNS response to an A or AAAA record
query, the DNS response MAY contain an empty answer, NXDOMAIN, or a
forged A or AAAA response, as desired by the DNS server. In
addition, if the query contained the OPT pseudo-RR the DNS server MAY
return more detail in the EXTRA-TEXT field as described in
Section 5.3.
Servers may decide to return small TTL values in filtered DNS
responses (e.g., 2 seconds) to handle domain category and reputation
updates.
5.3. Client Processing Response
On receipt of a DNS response with an Extended DNS Error option, the
following actions are performed if the EXTRA-TEXT field contains
valid JSON:
* The response MUST be received over an encrypted DNS channel. If
not, the requestor MUST discard data in the EXTRA-TEXT field.
* The response MUST be received from a DNS server which advertised
EDE support via a trusted channel, e.g., RESINFO
[I-D.reddy-add-resolver-info].
* Servers which don't support this specification might use plain
text in the EXTRA-TEXT field so that requestors SHOULD properly
handle both plaintext and JSON text in the EXTRA-TEXT field.
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* The DNS response MUST also contain an extended error code of
"Censored", "Blocked", "Filtered" or "Forged" [RFC8914], otherwise
the EXTRA-TEXT field is discarded.
* If either of the mandatory JSON names "c" and "j" are missing or
have empty values in the EXTRA-TEXT field, the entire JSON is
discarded.
* The JSON name "s" MUST NOT be present with the extended error code
"Censored".
* If a DNS client has enabled opportunistic privacy profile
(Section 5 of [RFC8310]) for DoT, the DNS client will either
fallback to an encrypted connection without authenticating the DNS
server provided by the local network or fallback to clear text
DNS, and cannot exchange encrypted DNS messages. Both of these
fallback mechanisms adversely impacts security and privacy. If
the DNS client has enabled opportunistic privacy profile for DoT,
the DNS client MUST ignore the EXTRA-TEXT field of the EDE
responses, but SHOULD process other parts of the response.
* If a DNS client has enabled strict privacy profile (Section 5 of
[RFC8310]) for DoT, the DNS client requires an encrypted
connection and successful authentication of the DNS server; this
mitigates both passive eavesdropping and client redirection (at
the expense of providing no DNS service if an encrypted,
authenticated connection is not available). If the DNS client has
enabled strict privacy profile for DoT, the client MAY process the
EXTRA-TEXT field of the DNS response. Note that the strict and
opportunistic privacy profiles as defined in [RFC8310] only apply
to DoT; there has been no such distinction made for DoH.
* If the DNS client determines that the encrypted DNS server does
not offer DNS filtering service, it MUST discard the EXTRA-TEXT
field of the EDE response. For example, the DNS client can learn
whether the encrypted DNS resolver performs DNS-based content
filtering or not by retrieving resolver information using the
method defined in [I-D.reddy-add-resolver-info].
* When a forwarder receives an EDE option, whether or not (and how)
to pass along JSON information in the EXTRA-TEXT on to their
client is implementation dependent [RFC5625]. Implementations MAY
choose to not forward the JSON information, or they MAY choose to
create a new EDE option that conveys the information in the "c",
"s" and "j" fields encoded in the JSON object.
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6. Interoperation with RPZ Servers
This section discusses operation with an RPZ server [RPZ] that
indicates filtering with a NXDOMAIN response with the Recursion
Available bit cleared (RA=0).
When the DNS client supports this specification but the server does
not, the server will continue replying when a query is RPZ filtered
with NXDOMAIN and RA=0. An DNS client upgraded to support this
specification can continue to accept responses with NXDOMAIN and RA=0
from the RPZ server that does not support this specification.
When the DNS client supports this specification and the server
supports this specification, the client learns of the server's
support via [I-D.reddy-add-resolver-info] and the client includes the
EDE OPT pseudo-RR in the query. This allows the server to
differentiate EDE-aware clients from EDE-unaware clients and respond
appropriately.
7. Examples
An example showing the nameserver at 'ns.example.net' that filtered a
DNS "A" record query for 'example.org' is shown in Figure 1.
{
"c": ["tel:+358-555-1234567", "sips:bob@bobphone.example.com",
"https://ticket.example.com?d=example.org&t=1650560748"],
"j": "malware present for 23 days",
"s": 1,
"o": "example.net Filtering Service"
}
Figure 1: JSON returned in EXTRA-TEXT field of Extended DNS Error
response
In Figure 2 the same content is shown with minified JSON (no
whitespace, no blank lines) with '\' line wrapping per [RFC8792].
============== NOTE: '\' line wrapping per RFC 8792 ===============
{"c":["tel:+358-555-1234567","sips:bob@bobphone.example.com", \
"https://ticket.example.com?d=example.org&t=1650560748"],"s":1, \
"j":"malware present for 23 days","o":"example.net Filtering \
Service"}
Figure 2: Minified response
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8. Security Considerations
Security considerations in Section 6 of [RFC8914] apply to this
document.
To minimize impact of active on-path attacks on the DNS channel, the
client validates the response as described in Section 5.3.
A client might choose to display the information in the EXTRA-TEXT
field if and only if the encrypted resolver has sufficient
reputation, according to some local policy (e.g. user configuration,
administrative configuration, or a built-in list of respectable
resolvers). This limits the ability of a malicious encrypted
resolver to cause harm. If the client decides not to display the all
of the information in the EXTRA-TEXT field, it can be logged for
diagnostics purpose and the client can only display the resolver
hostname that blocked the domain, error description for the EDE code
and the suberror description for the "s'" field to the end-user.
When displaying the free-form text of "c" and "o", the browser SHOULD
NOT make any of those elements into actionable (clickable) links.
An attacker might inject (or modify) the EDE EXTRA-TEXT field with an
DNS proxy or DNS forwarder that is unaware of EDE. Such a DNS proxy
or DNS forwarder will forward that attacker-controlled EDE option.
To prevent such an attack, clients supporting this document MUST
discard the EDE option if their DNS server does not signal EDE
support via RESINFO [I-D.reddy-add-resolver-info]. As recommended in
[I-D.reddy-add-resolver-info], RESINFO should be retrieved over an
encrypted DNS channel or integrity protected with DNSSEC.
9. IANA Considerationsd
This document requests IANA to register the "application/
json+structured-dns-error" media type in the "Media Types" registry
[IANA-MediaTypes]. This registration follows the procedures
specified in [RFC6838]:
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Type name: application
Subtype name: json+structured-dns-error
Required parameters: N/A
Optional parameters: N/A
Encoding considerations: as defined in Section NN of [RFCXXXX].
Security considerations: See Section NNN of [RFCXXXX].
Interoperability considerations: N/A
Published specification: [RFCXXXX]
Applications that use this media type: Section NNNN of [RFCXXXX].
Fragment identifier considerations: N/A
Additional information: N/A
Person & email address to contact for further information: IETF,
iesg@ietf.org
Intended usage: COMMON
Restrictions on usage: none
Author: See Authors' Addresses section.
Change controller: IESG
Provisional registration? No
9.1. New registry for SubError Codes
IANA is requested to create a new registry, entitled "SubError Codes"
under "Domain Name System (DNS) Parameters, Extended DNS Error Codes"
registry. A registration procedure for suberror codes MUST include
the following fields:
* Number: wire format suberror code (range 0-255)
* Meaning: a short description
* Reference: pointer to the specification text
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* Change Controller: Person or entity, with contact information if
appropriate.
New entries in this registry are subject to an Expert Review
registration policy [RFC8126]. The designated expert MUST ensure
that the Reference is stable and publicly available, and that it
specifies the suberror code and a short description. The Format
Reference may be any individual's Internet-Draft, or a document from
any other source with similar assurances of stability and
availability.
10. Initial Sub-errors
The registry shall initially be populated with the following suberror
codes. :
+========+=============================+===========+============+
| Number | Meaning | Reference | Change |
| | | | Controller |
+========+=============================+===========+============+
| 0 | Reserved | This | IETF |
| | | document | |
+--------+-----------------------------+-----------+------------+
| 1 | Malware | This | IETF |
| | | document | |
+--------+-----------------------------+-----------+------------+
| 2 | Phishing | This | IETF |
| | | document | |
+--------+-----------------------------+-----------+------------+
| 3 | Spam | This | IETF |
| | | document | |
+--------+-----------------------------+-----------+------------+
| 4 | Spyware | This | IETF |
| | | document | |
+--------+-----------------------------+-----------+------------+
| 5 | Adware | This | IETF |
| | | document | |
+--------+-----------------------------+-----------+------------+
| 6 | Network policy imposed by | This | IETF |
| | the operator of the network | document | |
+--------+-----------------------------+-----------+------------+
Table 1
11. Changes
This section is to be removed before publishing as an RFC.
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11.1. Changes from 03 to 04
* Clarified text content is for IT staff
* Introduced 'suberror' terminology and associated IANA registration
11.2. Changes from 02 to 03
* Require using RESINFO [I-D.reddy-add-resolver-info] in client
processing and added discussion of attack mitigation of using
RESINFO.
* Removed validation of URI domain suffix, which we can't do for
some URLs (e.g., tel:), is difficult/impossible for others when
3rd party is handling level one support (e.g., sips:). Instead
rely on RESINFO telling us if EDE is supported by the DNS server
and, if so, expect it to properly support EDE rather than blindly
forward an unknown DNS option.
* Removed 'partial URI' text
11.3. Changes from 01 to 02
* repurpose Extended DNS Error's EXTRA-TEXT field to carry JSON,
which also means this document updates RFC8914
* clarified DNS forwarders might forward EXTRA-TEXT without change
or might rewrite "j" and "d"
11.4. Changes from 00 to 01
* removed support for multiple responsible parties
* one-character JSON names to minimize JSON length
* partial URI sent in "c" and "r" names, combined with "d" name sent
in JSON to minimize attack surface and minimize JSON length
* moved EDNS(0) forgery-mitigation text, some Security
Considerations text, and some other text from
[I-D.reddy-dnsop-error-page] to this document
12. References
12.1. Normative References
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[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>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/info/rfc6838>.
[RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms
for DNS (EDNS(0))", STD 75, RFC 6891,
DOI 10.17487/RFC6891, April 2013,
<https://www.rfc-editor.org/info/rfc6891>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <https://www.rfc-editor.org/info/rfc7159>.
[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493,
DOI 10.17487/RFC7493, March 2015,
<https://www.rfc-editor.org/info/rfc7493>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8310] Dickinson, S., Gillmor, D., and T. Reddy, "Usage Profiles
for DNS over TLS and DNS over DTLS", RFC 8310,
DOI 10.17487/RFC8310, March 2018,
<https://www.rfc-editor.org/info/rfc8310>.
12.2. Informative References
[I-D.reddy-add-resolver-info]
Reddy, T. and M. Boucadair, "DNS Resolver Information",
Work in Progress, Internet-Draft, draft-reddy-add-
resolver-info-06, 31 August 2022,
<https://www.ietf.org/archive/id/draft-reddy-add-resolver-
info-06.txt>.
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[I-D.reddy-dnsop-error-page]
Reddy, T., Cook, N., Wing, D., and M. Boucadair, "DNS
Access Denied Error Page", Work in Progress, Internet-
Draft, draft-reddy-dnsop-error-page-08, 4 June 2021,
<https://www.ietf.org/archive/id/draft-reddy-dnsop-error-
page-08.txt>.
[IANA-MediaTypes]
IANA, "Media Types",
<https://www.iana.org/assignments/media-types>.
[RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines",
BCP 152, RFC 5625, DOI 10.17487/RFC5625, August 2009,
<https://www.rfc-editor.org/info/rfc5625>.
[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
and P. Hoffman, "Specification for DNS over Transport
Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
2016, <https://www.rfc-editor.org/info/rfc7858>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
[RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS
(DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018,
<https://www.rfc-editor.org/info/rfc8484>.
[RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
January 2019, <https://www.rfc-editor.org/info/rfc8499>.
[RFC8792] Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
"Handling Long Lines in Content of Internet-Drafts and
RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
<https://www.rfc-editor.org/info/rfc8792>.
[RFC8914] Kumari, W., Hunt, E., Arends, R., Hardaker, W., and D.
Lawrence, "Extended DNS Errors", RFC 8914,
DOI 10.17487/RFC8914, October 2020,
<https://www.rfc-editor.org/info/rfc8914>.
[RFC9250] Huitema, C., Dickinson, S., and A. Mankin, "DNS over
Dedicated QUIC Connections", RFC 9250,
DOI 10.17487/RFC9250, May 2022,
<https://www.rfc-editor.org/info/rfc9250>.
Wing, et al. Expires 25 March 2023 [Page 15]
Internet-Draft Data for Filtered DNS September 2022
[RPZ] Wikipedia, "Response policy zone",
<https://en.wikipedia.org/w/index.php>.
Authors' Addresses
Dan Wing
Citrix Systems, Inc.
United States of America
Email: dwing-ietf@fuggles.com
Tirumaleswar Reddy
Nokia
Bangalore
Karnataka
India
Email: kondtir@gmail.com
Neil Cook
Open-Xchange
United Kingdom
Email: neil.cook@noware.co.uk
Mohamed Boucadair
Orange
35000 Rennes
France
Email: mohamed.boucadair@orange.com
Wing, et al. Expires 25 March 2023 [Page 16]