DNS-over-HTTPS and DNS-over-TLS Server Discovery and Deployment Considerations for Home Networks
draft-btw-add-home-05
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Mohamed Boucadair , Tirumaleswar Reddy.K , Dan Wing , Neil Cook | ||
| Last updated | 2020-04-02 | ||
| Replaced by | draft-ietf-add-dnr, RFC 9463 | ||
| RFC stream | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-btw-add-home-05
ADD M. Boucadair
Internet-Draft Orange
Intended status: Standards Track T. Reddy
Expires: October 4, 2020 McAfee
D. Wing
Citrix
N. Cook
Open-Xchange
April 2, 2020
DNS-over-HTTPS and DNS-over-TLS Server Discovery and Deployment
Considerations for Home Networks
draft-btw-add-home-05
Abstract
This document discusses DoT/DoH deployment considerations for home
networks. It particularly sketches the required steps to use DoT/DoH
capabilities provided by local networks.
One of the goals of this document is to assess to what extent
existing tools can be used to provide a DoT/DoH service. As an
outcome, new DHCP and Router Advertisement Options are specified in
order to convey a DNS Authentication Domain Name.
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 October 4, 2020.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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 and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Sample Deployment Scenarios . . . . . . . . . . . . . . . . . 5
3.1. Managed CPEs . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Unmanaged CPEs . . . . . . . . . . . . . . . . . . . . . 7
4. DNS Reference Identifier Option . . . . . . . . . . . . . . . 8
4.1. DHCPv6 DNS Reference Identifier Option . . . . . . . . . 9
4.2. DHCP DNS Reference Identifier Option . . . . . . . . . . 10
4.3. RA DNS Reference Identifier Option . . . . . . . . . . . 12
5. DoH URI Templates . . . . . . . . . . . . . . . . . . . . . . 13
5.1. Define a Dedicated DHCP/RA Option . . . . . . . . . . . . 13
5.2. Retrieve the List Directly from the DoH Server . . . . . 14
6. Locating DoH/DoT Servers . . . . . . . . . . . . . . . . . . 14
6.1. DoT/DoH Auto-Upgrade . . . . . . . . . . . . . . . . . . 16
6.2. Other Deployment Options . . . . . . . . . . . . . . . . 17
7. Hosting DoH/DoT Forwarder in the CPE . . . . . . . . . . . . 17
7.1. Managed CPEs . . . . . . . . . . . . . . . . . . . . . . 18
7.1.1. ACME . . . . . . . . . . . . . . . . . . . . . . . . 18
7.1.2. Redirection . . . . . . . . . . . . . . . . . . . . . 18
7.1.2.1. Server-Driven Redirection . . . . . . . . . . . . 18
7.1.2.2. Client-Initiated Redirection . . . . . . . . . . 19
7.1.3. Auto-Upgrade based on Domains and their Sub-domains . 21
7.2. Unmanaged CPEs . . . . . . . . . . . . . . . . . . . . . 22
8. Security Considerations . . . . . . . . . . . . . . . . . . . 23
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
9.1. DHCPv6 Option . . . . . . . . . . . . . . . . . . . . . . 24
9.2. DHCP Option . . . . . . . . . . . . . . . . . . . . . . . 25
9.3. RA Option . . . . . . . . . . . . . . . . . . . . . . . . 25
9.4. Service Name . . . . . . . . . . . . . . . . . . . . . . 25
9.5. Encrypted DNS Types . . . . . . . . . . . . . . . . . . . 26
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
11.1. Normative References . . . . . . . . . . . . . . . . . . 26
11.2. Informative References . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30
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1. Introduction
Internet Service Providers (ISPs) traditionally provide DNS resolvers
to their customers. Typically, ISPs deploy the following mechanisms
to advertise a list of DNS Recursive DNS server(s) to their
customers:
o Protocol Configuration Options in cellular networks [TS.24008].
o DHCP [RFC2132] (Domain Name Server Option) or DHCPv6
[RFC8415][RFC3646] (OPTION_DNS_SERVERS).
o IPv6 Router Advertisement [RFC4861][RFC8106] (Type 25 (Recursive
DNS Server Option)).
The communication between a customer's device (possibly via Customer
Premises Equipment (CPE)) and an ISP-supplied DNS resolver takes
place by using cleartext DNS messages (Do53,
[I-D.ietf-dnsop-terminology-ter]). Some examples are depicted in
Figure 1. In the case of cellular networks, the cellular network
will provide connectivity directly to a host (e.g., smartphone,
tablet) or via a CPE. Do53 mechanisms used within the Local Area
Network (LAN) are similar in both fixed and cellular CPE-based
broadband service offerings.
(a) Fixed Networks
,--,--,--. ,--,--,--.
,-' +--+ `-. ,-' ISP `-.
( LAN |H | CPE----( )
`-. +--+ ,-' `-. ,-'
`--'|-'--' `--'--'--'
| |
|<=======Do53========>|
(b) Cellular Networks
|<===========Do53=========>|
,--,-|,--. |
,-' +--+ `-. ,--,--,--.
( LAN |H | CPE------------+ \
`-. +--+ ,-' ,' ISP `-.
`--'--'--' ( )
+-----+-. ,-'
+--+ | `--'--'--'
|H +------------+
+--+
Legend:
* H: refers to a host.
Figure 1: Sample Legacy Deployments
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ISPs use DNS to provide additional services such as (but not limited
to) malware filtering, parental control, or VoD (Video on Demand)
optimization. DNS is also a central component for mastering the
quality of experience for current latency-sensitive services, but
also emerging ones (such as those services that pertain to the Ultra
Reliability and Low Latency Communications (uRLLC) or Enhanced Mobile
Broadband (eMBB).
For example, the latency targets set in the context of 5G are 1ms
(uRLLC) and 4ms (eMBB). An ISP will be able to address such
demanding latency requirements assuming the corresponding services
rely upon resources (network, compute, storage) that are located
as close to the user as possible (e.g., by means of Edge Computing
techniques and resources). Such latency requirements are likely
to be addressed by means of optimized designs (DNS, in
particular), too.
Relying upon local DNS resolvers will therefore contribute to meet
the aforementioned service requirements. The use of external
resolvers is likely to induce an extra service delay which exceeds by
far the service target.
This document focuses on the support of DNS-over-HTTPS (DoH)
[RFC8484] or DNS-over-TLS (DoT) [RFC7858] in local networks. In
particular, the document describes how a local DoH/DoT server can be
discovered and used by connected hosts. This document specifies
options that allow DNS clients to discover local DoT/DoH servers.
Section 4 describes DHCP, DHCPv6, and RA options to convey the
Authentication Domain Name (ADN, defined in [RFC8310]).
Some ISPs rely upon external resolvers (e.g., outsourced service or
public resolvers); these ISPs provide their customers with the IP
addresses of these resolvers. These addresses are typically
configured on CPEs using the same mechanisms listed above. Likewise,
users can modify the default DNS configuration of their CPEs (e.g.,
supplied by their ISP) to configure their favorite DNS servers. This
document permits such deployments.
Both managed and unmanaged CPEs are discussed in the document
(Section 3). Also, considerations related to hosting a DNS forwarder
in the CPE are described (Section 7).
Hosts and/or CPEs may be connected to multiple networks; each
providing their own DNS configuration using the discovery mechanisms
specified in this document. Nevertheless, it is out of the scope of
this specification to discuss DNS selection of multi-interface
devices. The reader may refer to [RFC6731] for a discussion of
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issues and an example of DNS server selection for multi-interfaced
devices.
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 makes use of the terms defined in [RFC8499] and
[I-D.ietf-dnsop-terminology-ter].
Do53 refers to unencrypted DNS.
'DoH/DoT' refers to DNS-over-HTTPS and/or DNS-over-TLS.
3. Sample Deployment Scenarios
3.1. Managed CPEs
ISPs have developed an expertise in managing service-specific
configuration information (e.g., CPE WAN Management Protocol
[TR-069]). For example, these tools may be used to provision the
authentication domain name information (ADN) to managed CPEs if DoH/
DoT is supported by a local network similar to what is depicted in
Figure 2.
DoH-capable (or DoT) clients establish the DoH (or DoT) session with
the discovered DoH (or DoT) server.
The DNS client discovers whether the DNS server in the local network
supports DoH/DoT by using a dedicated field in the discovery message:
Encrypted DNS Type (Section 4).
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(a) Fixed Networks
,--,--,--. ,--,--,--.
,-' +--+ `-. ,-' ISP `-.
( LAN |H | CPE----( DNS Server )
`-. +--+ ,-' `-. ,-'
`--'|-'--' `--'--'--'
| |
|<=======DoH/DoT=====>|
(b) Cellular Networks
|<===========DoH/DoT======>|
,--,-|,--. |
,-' +--+ `-. ,--,--,--.
( LAN |H | CPE------------+ \
`-. +--+ ,-' ,' ISP `-.
`--'--'--' ( DNS Server )
+-----+-. ,-'
+--+ | `--'--'--'
|H +-----------+
+--+
Figure 2: DoH/DoT in the WAN
Figure 2 shows the scenario where the CPE relays the list of DoT/DoH
servers it learns for the network by using mechanisms like DHCP or a
specific Router Advertisement message. In such context, direct DoH/
DoT sessions will be established between a host serviced by a CPE and
an ISP-supplied DoT/DoH server (see the example depicted in Figure 3
for a DoH/DoT-capable host).
,--,--,--. ,--,--,--.
,-' `-. ,-' ISP `-.
Host---( LAN CPE----( DNS Server )
| `-. ,-' `-. ,-'
| `--'--'--' `--'--'--'
| |
|<==============DoT/DoH============>|
Figure 3: Direct DoH/DoT Sessions
Figure 4 shows a deployment where the CPE embeds a caching DNS
forwarder. The CPE advertises itself as the default DNS server to
the hosts it serves. The CPE relies upon DHCP or RA to advertise
itself to internal hosts as the default DoT/DoH/Do53 server. When
receiving a DNS request it cannot handle locally, the CPE forwards
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the request to an upstream DoH/DoT/Do53 resolver. Such deployment is
required for IPv4 service continuity purposes (e.g.,
[I-D.ietf-v6ops-rfc7084-bis]) or for supporting advanced services
within the home (e.g., malware filtering, parental control,
Manufacturer Usage Description (MUD, [RFC8520] to only allow intended
communications to and from an IoT device)). When the CPE behaves as
a DNS forwarder, DNS communications can be decomposed into two legs:
o The leg between an internal host and the CPE.
o The leg between the CPE and an upstream DNS resolver.
An ISP that offers DoH/DoT to its customers may enable DoH/DoT in
both legs as shown in Figure 4. Additional considerations related to
this deployment are discussed in Section 7.
,--,--,--. ,--,--,--.
,-' `-. ,-' ISP `-.
Host---( LAN CPE----( DNS Server )
| `-. ,-'| `-. ,-'
| `--'--'--' | `--'--'--'
| | |
|<======DoT/DoH======>|<==DoT/DoH==>|
Figure 4: Proxied DoH/DoT Sessions
3.2. Unmanaged CPEs
Customers may decide to deploy unmanaged CPEs (assuming the CPE is
compliant with the network access technical specification that is
usually published by ISPs). Upon attachment to the network, an
unmanaged CPE receives from the network its service configuration
(including the DNS information) by means of, e.g., DHCP. That DNS
information is shared within the LAN following the same mechanisms as
those discussed in Section 3.1. A host can thus establish DoH/DoT
session with a DoH/DoT server similar to what is depicted in
Figure 3.
Customers may also decide to deploy internal home routers (called
hereafter, Internal CPEs) for a variety of reasons that are not
detailed here. Absent any explicit configuration on the internal CPE
to override the DNS configuration it receives from the ISP-supplied
CPE, an Internal CPE relays the DNS information it receives via DHCP/
RA from the ISP-supplied CPE to connected hosts. DoH/DoT sessions
can be established by a host with the DoH/DoT servers of the ISP (see
Figure 5).
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,--,--,--. ,--,--,--.
,-' Internal ,-' ISP `-.
Host--( Network#A CPE----CPE---( DNS Server )
| `-. ,-' `-. ,-'
| `--'--'--' `--'--'--'
| |
|<===================DoT/DoH==============>|
Figure 5: Direct DoH/DoT Sessions with the ISP DNS Resolver (Internal
CPE)
Similar to managed CPEs, a user may modify the default DNS
configuration of an unmanaged CPE to use his/her favorite DNS servers
instead. DoH/DoT sessions can be established directly between a host
and a 3rd Party DNS server (see Figure 6).
,--,--,--. ,--,
,' Internal ,-' '- 3rd Party
Host--( Network#A CPE----CPE---( ISP )--- DNS Server
| `. ,-' `-. -' |
| `-'--'--' `--' |
| |
|<======================DoT/DoH===================>|
Figure 6: Direct DoH/DoT Sessions with a Third Party DNS Resolver
Section 7.2 discusses considerations related to hosting a forwarder
in the Internal CPE.
4. DNS Reference Identifier Option
This section describes how a DNS client can discover the ADN of local
DoH/DoT server(s) using DHCP (Sections 4.1 and 4.2) and Neighbor
Discovery protocol (Section 4.3).
As reported in Section 1.7.2 of [RFC6125]:
"few certification authorities issue server certificates based on
IP addresses, but preliminary evidence indicates that such
certificates are a very small percentage (less than 1%) of issued
certificates".
In order to allow for PKIX-based authentication between a DNS client
and a DoH/DoT server while accommodating the current best practices
for issuing certificates, this document allows for configuring an
authentication domain name to be presented as a reference identifier
for DNS authentication purposes.
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The DNS client establishes a DoH/DoT session with the discovered DNS
IP address(es) (Section 6) and uses the mechanism discussed in
Section 8 of [RFC8310] to authenticate the DNS server certificate
using the authentication domain name conveyed in the DNS Reference
Identifier.
If the DNS Reference Identifier is discovered by a host using both RA
and DHCP, the rules discussed in Section 5.3.1 of [RFC8106] MUST be
followed.
4.1. DHCPv6 DNS Reference Identifier Option
The DHCPv6 DNS Reference Identifier option is used to configure an
authentication domain name of the DoH/DoT server. The format of this
option is shown in Figure 7.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_V6_DNS_RI | Option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|F|Encr DNS Type| |
+-+-------------+ |
| |
~ Authentication Domain Name ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: DHCPv6 DNS Reference Identifier Option
The fields of the option shown in Figure 7 are as follows:
o Option-code: OPTION_V6_DNS_RI (TBA1, see Section 9.1)
o Option-length: Length of the enclosed data in octets.
o F bit: Forwarder bit. If set, it instructs the DNS client to
retrieve the forwarder identifier from the resolver identified by
the Authentication Domain Name (Section 7).
o Encr DNS Type (Encrypted DNS Type): Indicates the type of the
encrypted DNS server conveyed in this attribute. The following
values are defined:
0: Any encrypted DNS
1: DoT
2: DoH
See Section 9.5 for future assignment considerations.
o Authentication Domain Name: A fully qualified domain name of the
DoH/DoT server. This field is formatted as specified in
Section 10 of [RFC8415].
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An example of the Authentication Domain Name encoding is shown in
Figure 8. This example conveys the FQDN "doh1.example.com.".
+------+------+------+------+------+------+------+------+------+
| 0x04 | d | o | h | 1 | 0x07 | e | x | a |
+------+------+------+------+------+------+------+------+------+
| m | p | l | e | 0x03 | c | o | m | 0x00 |
+------+------+------+------+------+------+------+------+------+
Figure 8: An example of the authentication-domain-name Encoding
Multiple instances of OPTION_V6_DNS_RI may be returned to a DHCPv6
client; each pointing to a distinct encrypted DNS server type.
To discover an encrypted DNS server, the DHCPv6 client including
OPTION_V6_DNS_RI in an Option Request Option (ORO), as in Sections
18.2.1, 18.2.2, 18.2.4, 18.2.5, 18.2.6, and 21.7 of [RFC8415]. The
DHCPv6 client sets the Encrypted DNS Type field to the requested
encrypted DNS server.
If the DHCPv6 client requested any encrypted DNS server, the DHCP
client MUST be prepared to receive multiple DHCP OPTION_V6_DNS_RI
options; each option is to be treated as a separate encrypted DNS
server.
4.2. DHCP DNS Reference Identifier Option
The DHCP DNS Reference Identifier option is used to configure an
authentication domain name of the DoH/DoT server. The format of this
option is illustrated in Figure 9.
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TBA2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|F|Encr DNS Type| |
+-+-+-+-+-+-+-+-+ |
| |
~ Authentication Domain Name ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
with:
Authentication Domain Name
+-----+-----+-----+-----+-----+--
| s1 | s2 | s3 | s4 | s5 | ...
+-----+-----+-----+-----+-----+--
The values s1, s2, s3, etc. represent the domain name labels in the
domain name encoding.
Figure 9: DHCP DNS Reference Identifier Option
The fields of the option shown in Figure 9 are as follows:
o Code: OPTION_V4_DNS_RI (TBA2, see Section 9.2).
o Length: Length of the enclosed data in octets.
o F bit: Forwarder bit. If set, it instructs the DNS client to
retrieve the forwarder identifier from the resolver identified by
the Authentication Domain Name (Section 7).
o Encr DNS Type (Encrypted DNS Type): Indicates the type of the
encrypted DNS server conveyed in this attribute. The following
values are defined:
0: Any encrypted DNS
1: DoT
2: DoH
See Section 9.5 for future assignment considerations.
o Authentication Domain Name: The domain name of the DoH/DoT server.
This field is formatted as specified in Section 10 of [RFC8415].
OPTION_V4_DNS_RI is a concatenation-requiring option. As such, the
mechanism specified in [RFC3396] MUST be used if OPTION_V4_DNS_RI
exceeds the maximum DHCP option size of 255 octets.
To discover an encrypted DNS server, the DHCP client requests the
Encrypted DNS Reference Identifier by including OPTION_V4_DNS_RI in a
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Parameter Request List option [RFC2132]. The DHCP client sets the
Encrypted DNS Type field to the requested encrypted DNS server.
If the DHCP client requested any encrypted DNS server, the DHCP
client MUST be prepared to receive multiple DHCP OPTION_V4_DNS_RI
options; each option is to be treated as a separate encrypted DNS
server.
4.3. RA DNS Reference Identifier Option
The IPv6 Router Advertisement (RA) DNS Reference Identifier option is
used to configure an authentication domain name of the DoH/DoT
server. The format of this option is illustrated in Figure 10.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |F|Encr DNS Type| Unassigned |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: Authentication Domain Name :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: RA DNS Reference Identifier Option
The fields of the option shown in Figure 10 are as follows:
o Type: 8-bit identifier of the DNS Reference Identifier Option as
assigned by IANA (TBA3, see Section 9.3).
o Length: 8-bit unsigned integer. The length of the option
(including the Type and Length fields) is in units of 8 octets.
o F bit: Forwarder bit. If set, it instructs the DNS client to
retrieve the forwarder identifier from the resolver identified by
the Authentication Domain Name (Section 7).
o Encr DNS Type (Encrypted DNS Type): Indicates the type of the
encrypted DNS server conveyed in this attribute. The following
values are defined:
0: Any encrypted DNS
1: DoT
2: DoH
See Section 9.5 for future assignment considerations.
o Unassigned: This field is unused. It MUST be initialized to zero
by the sender and MUST be ignored by the receiver.
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o Lifetime: 32-bit unsigned integer. The maximum time in seconds
(relative to the time the packet is received) over which the
authentication domain name MAY be used as a DNS Reference
Identifier.
The value of Lifetime SHOULD by default be at least 3 *
MaxRtrAdvInterval, where MaxRtrAdvInterval is the maximum RA
interval as defined in [RFC4861].
A value of all one bits (0xffffffff) represents infinity.
A value of zero means that the DNS Reference Identifier MUST no
longer be used.
o Authentication Domain Name: The domain name of the DoH/DoT server.
This field is formatted as specified in Section 10 of [RFC8415].
This field MUST be padded with zeros so that its size is a
multiple of 8 octets.
5. DoH URI Templates
DoH servers may support more than one URI Template [RFC8484]. The
following sub-sections discuss some candidate solutions for a DoH
client to retrieve the list of supported templates by a DoH server.
Also, if the resolver hosts several DoH services (e.g., no-filtering,
blocking adult content, blocking malware), these services can be
discovered as templates.
How a DoH client makes use of the configured DoH services is out of
scope of this document.
o DISCUSSION: More feedback is needed to assess whether URI RA/DHCP
options have to be specified.
5.1. Define a Dedicated DHCP/RA Option
This solution assumes that DHCP servers and access routers maintain
an updated list of the templates used by DoH resolvers.
The following observations can be made:
o In order to avoid that stale DoH information is supplied to
connected devices, each time the URI templates are updated at a
DoH resolver (e.g., add a new DoH service, withdraw a DoH
service), DHCP servers (or access routers for the RA case) have to
be updated accordingly to reflect the DNS service change.
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o This dependency may be affordable if the ISP providing the
connectivity service is also the one operating the DoH resolver.
o Nevertheless, if the DNS service is provided by a distinct entity
than the ISP, an out-of-band mechanism is required to synchronize
the list of DoH services that are active on a DoH resolver vs. the
list maintained locally by the ISP.
o Also, it is not clear how enclosed URI templates will be validated
by DHCP clients given that future specifications may allow for
other variables in the URI.
o Including a large list of templates may cause the size of an RA to
exceed the link MTU. In such case, multiple RAs must be used.
RA/DHCP has the following advantages:
o Notify clients whenever there is a change in the DoH service
configuration.
o The DoH client can immediately use available DoH services.
o It is convenient if very few (stable) URIs are in use.
o It allows for customized configuration within the home network.
For example, a child host can be provided by the CPE with a DoH
server that supports parental filtering, while other hosts can be
provisioned with a DoH server that does not enable such
capabilities.
5.2. Retrieve the List Directly from the DoH Server
Upon discovery of a DoH resolver (Section 4), the DoH client contacts
that DoH resolver to retrieve the list of supported DoH services
(e.g., use of a well-known URI). That information is cached by the
DoH client for a given period (e.g., 24h). DoH clients re-iterates
that request regularly (e.g., 24h) to retrieve an updated list of
supported DoH services. Note that a "push" mode can be considered
using the mechanism defined in [I-D.ietf-dnssd-push].
This approach allows to avoid adherence of DoH servers with DHCP
servers (or access routers) for (de)activating new DoH services.
6. Locating DoH/DoT Servers
A CPE or a host relies upon discovery mechanisms (such as PCO, DHCP,
or RA) to retrieve DoH/DoT servers' reachability information. In the
various scenarios sketched in Section 3, Do53, DoH, and DoT may
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terminate on the same IP address (or distinct IP addresses as
depicted in Figure 12). Terminating Do53/DoH/DoT on the same or
distinct IP addresses is deployment-specific.
From an IP reachability standpoint, DoH/DoT servers SHOULD be located
by their address literals rather than their names. This avoids
adding a dependency on another server to resolve the DoH/DoT name.
Concretely, if Do53/DoH/DoT terminate on same IP addresses, existing
discovery mechanisms [RFC2132][RFC3646][RFC8106] can be leveraged to
learn the IP addresses of DoT/DoH servers while an authentication
domain name is supplied by one of the options discussed in Section 4.
An example is depicted in Figure 11.
Legacy Do53
client
|<===DHCP===>|
| {@1} | |
| | |
|======Do53 Query===>|
| | | --,--,-
,+-,--,--. | |,/ ISP \.
,-' `-. | ,-' `-.
DoH/DoT --( LAN CPE----( S (@1) )
capable client `-. ,-'| `-. ,-'
| `--'--'--' | | `--'--'--'
|<========DHCP========>| |
| {RI, @1} | |
| |
|<=========DoT/DoH============>|
Legend:
* S: DNS server
* {@1}: IP address of S; returned in a DHCP
Domain Name Server option
* RI: DNS Reference Identifier
Figure 11: Locating DoH/DoT/Do53 (Same DNS Server)
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Legacy Do53
client
|<===RA======|
| {RI,@1,@2} | |
| | |
|========Do53 Query=======>|
| | --,--,-
,+-,--,--. | ,/ S1 (@1)\.
,-' `-. | ,-' ISP `-.
DoH/DoT --( LAN CPE----( )
capable client `-. ,-'| `-. S2 (@2) ,-'
| `--'--'--' | `--'--'--'
|<=========RA==========| |
| {RI,@1,@2} | |
| |
|<===============DoT/DoH============>|
Legend:
* S1: Do53 server
* S2: DoH/DoT server
* @1: IP address of S1
* @1: IP address of S2
* RI: DNS Reference Identifier
Figure 12: Locating DoH/DoT/Do53 (Distinct Servers)
The following sub-sections discusses the conditions under which
discovered DoT/DoH server can be used.
6.1. DoT/DoH Auto-Upgrade
Additional considerations are discussed below for the use of DoH and
DoT servers provided by local networks:
o If the DNS server's IP address discovered by using DHCP/RA is pre-
configured in the OS or Browser as a verified resolver (e.g., part
of an auto-upgrade program such as [Auto-upgrade]), the DNS client
auto-upgrades to use the pre-configured DoH/DoT server tied to the
discovered DNS server IP address. In such a case the DNS client
will perform additional checks out of band, such as confirming
that the Do53 IP address and the DoH server are owned and operated
by the same organisation.
o Similarly, if the ADN conveyed in DHCP/RA (Section 4) is pre-
configured in the OS or browser as a verified resolver, the DNS
client auto-upgrades to establish a DoH/DoT session with the ADN.
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In such case, the DNS client matches the domain name in the DNS
Reference Identifier DHCP/RA option with the 'DNS-ID' identifier
type within subjectAltName entry in the server certificate
conveyed in the TLS handshake.
Such an auto-upgrade mechanism would be compatible with the
Redirection method of Section 7.1.2, for managed CPEs hosting a DoT/
DoH forwarder.
6.2. Other Deployment Options
Some deployment options to securely configure hosts are discussed
below. These options are provided for the sake of completeness.
o If Device Provisioning Protocol (DPP) [DPP] is used, the
configurator can securely configure devices in the home network
with the local DoT/DoH server using DPP. If the DoT/DoH servers
use raw public keys [RFC7250], the Subject Public Key Info (SPKI)
pin set [RFC7250] of raw public keys may be encoded in a QR code.
The configurator (e.g., mobile device) can scan the QR code and
provision SPKI pin set in OS/Browser. The configurator can in-
turn securely configure devices (e.g., thermostat) in the home
network with the SPKI pin set using DPP.
o If a CPE is co-located with security services within the home
network, the CPE can use WPA-PSK but with unique pre-shared keys
for different endpoints to deal with security issues. In such
networks, [I-D.reddy-dprive-bootstrap-dns-server] may be used to
securely bootstrap endpoint devices with the authentication domain
name and DNS server certificate of the local network's DoH/DoT
server.
The OS would not know if the WPA pre-shared-key is the same for
all clients or a unique pre-shared key is assigned to the host.
Hence, the user has to indicate to the system that a unique pre-
shared key is assigned to trigger the bootstrapping procedure.
If the device joins a home network using a single shared password
among all the attached devices, a compromised device can host a
fake access point, and the device cannot be securely bootstrapped
with the home network's DoH/DoT server.
7. Hosting DoH/DoT Forwarder in the CPE
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7.1. Managed CPEs
The following mechanisms can be used to host a DoH/DoT forwarder in a
managed CPE (Section 3.1).
7.1.1. ACME
The ISP can assign a unique FQDN (e.g., cpe1.example.com) and a
domain-validated public certificate to the DoH/DoT forwarder hosted
on the CPE. Automatic Certificate Management Environment (ACME)
[RFC8555] can be used by the ISP to automate certificate management
functions such as domain validation procedure, certificate issuance
and certificate revocation.
The managed CPE should support a configuration parameter to instruct
the CPE whether it has to relay the encrypted DNS server received
from the ISP's network or has to announce itself as a forwarder
within the local network. The default behavior of the CPE is to
supply the encrypted DNS server received from the ISP's network.
If the CPE announces itself as a DNS forwarder, the F-bit MUST NOT be
set.
7.1.2. Redirection
7.1.2.1. Server-Driven Redirection
The mechanism specified in this section is specific to DoH.
An ISP-managed CPE can be configured with the ISP's DoH resolver IP
addresses and ADN, which it will communicate to internal hosts using
DHCP/RA (Section 4). Upon joining the network, a DoH client follows
the procedure specified in Section 6.1 to upgrade to DoH.
Once the DoH session is established, the ISP DoH server uses HTTP
redirection (Section 6.4.4 in [RFC7231] and [RFC7538]) to redirect
the DNS client to the DoH forwarder hosted on the CPE (e.g.,
cpe1-internal.example.net). The DNS client either uses Do53 to
resolve the domain name in the redirected URI and eventually
establishes DoH session with the DoH forwarder in the CPE reachable
on the LAN interface. A simplified example is illustrated in
Figure 13.
PKIX authentication [RFC6125] based upon the domain name in the
redirected URI will detect rogue DNS servers.
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A DNS client that successfully connects to a redirected DoH server
may choose to locally cache the server host IP addresses in order to
not have to repeat the Do53 query.
--,--,-
,+-,--,--. ,/ ISP \.
,-' `-. ,-' `-.
DoH/DoT --( LAN CPE----( S (@1) )
capable client `-. ,-'| `-. ,-'
| `--'--'--' | | `--'--'--'
|<========DHCP========>| |
| {RI, @1} | |
| |
|<============DoH=============>|
|<--308 Permanent Redirect-----|
| |
|--------Do53 Query----------->|
|<--------CPE's LAN @----------|
| |
|<========DoH=========>|
| |
Legend:
* S: DoH/DoT server
* @1: IP address of S
Figure 13: A Simplified Example of Server-Driven Redirection
Notes:
* As an optimization, the redirect response can be modified to
include a list of IPv4/IPv6 addresses in addition to the CPE's
name.
[RFC7838] allows an origin's resource to be authoritatively
available at a separate network location, nevertheless it
requires the alternative service to present a certificate for
the origin's host name. This is not acceptable for the case
discussed in this section.
* Clients not caching the redirect information may experience an
extra delay for each request.
7.1.2.2. Client-Initiated Redirection
This section assumes that the procedure discussed in Section 7.1.2.1
is disabled.
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An ISP-managed CPE can be configured with the ISP's DoH/DoT resolver
IP addresses and ADN, which it will communicate to internal hosts
using DHCP/RA (Section 4). In addition, the CPE sets the F-bit to
inform the client that a forwarder is available locally.
Upon joining the LAN, a DoH/DoT client follows the procedure
specified in Section 6.1 to upgrade to DoH/DoT.
Once the DoH/DoT session is established, and given that F-bit is set,
the DoH/DoT client uses SRV resource record lookup for discovering
the DoH/DoT forwarder available in the local network to redirect the
DNS client to the DoH/DoT forwarder hosted on the CPE (e.g.,
cpe1-internal.example.net). A simplified example is illustrated in
Figure 14.
_domain-s._tcp.example.net SRV 0 0 853 cpe1-internal.example.net
cpe1-internal.example.net AAAA 2001:db8:8:4::2
cpe1-internal.example.net A 198.51.100.2
Figure 14: DoT Redirect Example
The <Service> portion of the DNS service instance name MUST be
"_domain-s._tcp" (Section 6 of [RFC7858]) or "_doh._tcp"
(Section 9.4).
The SRV record can only convey a sub-domain of the parent domain
otherwise the SRV record MUST be rejected by the DoH/DoT client.
A DNS client that successfully connects to a redirected DoH/DoT
server may choose to locally cache the server IP addresses in order
to avoid repeating the SRV lookup.
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--,--,-
,+-,--,--. ,/ ISP \.
,-' `-. ,-' `-.
DoH/DoT --( LAN CPE----( S (@1) )
capable client `-. ,-'| `-. ,-'
| `--'--'--' | | `--'--'--'
|<========DHCP========>| |
| {ADN, F=1, @1} | |
| |
| /==========================\ |
|| DoH: SRV Lookup (ADN) ||
|| cpe1-internal.example.net ||
|| AAAA ==> 2001:db8:8:4::2 ||
|| A ==> 198.51.100.2 ||
| \==========================/ |
|
|
|<========DoH=========>|
| |
Legend:
* S: DoH/DoT server
* @1: IP address of S
* F: Forwarding bit
Figure 15: A Simplified Example of Client-Initiated Redirection
7.1.3. Auto-Upgrade based on Domains and their Sub-domains
If the ADN conveyed in DHCP/RA (Section 4) is pre-configured in
popular OSes or browsers as a verified resolver and the auto-upgrade
(Section 6.1) is allowed for both the pre-configured ADN and its sub-
domains, the redirection mechanisms discussed in Section 7.1.2 can be
avoided. Concretely, the CPE can communicate the ADN of the local
DoH forwarder (Section 7.1.1) to internal hosts using DHCP/RA
(Section 4).
Let's suppose that "example.net" is pre-configured as a verified
resolved in the browser or OS. If the DoH/DoT client discovers a
local forwarder "cpe1-internal.example.net", the DoH/DoT client will
auto-upgrade because the pre-configured ADN would match
subjectAltName value "cpe1-internal.example.net" of type dNSName. As
shown in Figure 16, the auto-upgrade to a rogue server advertising
"rs.example.org" will fail.
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Rogue Server
| |
X<==DHCP=======|
| {ADN= |
| rs.example.org, F=0, @rs}
| | --,--,-
| ,+-,--+--. ,/ ISP \.
| ,-' `-. ,-' `-.
DoH/DoT --( LAN CPE----( S (@1) )
capable client `-. ,-'| `-. ,-'
| `--'--'--' | `--'--'--'
|<========DHCP========>|
|{ADN= |
| cpe1-internal.example.net, F=0, @i}
|
|<========DoH=========>|
| |
Legend:
* S: DoH/DoT server
* @1: IP address of S
* @i: internal IP address of the CPE
* @rs: IP address of a rogue server
Figure 16: A Simplified Example of Auto-upgrade based on Sub-domains
7.2. Unmanaged CPEs
The approach specified in Section 7.1 does not apply for hosting a
DNS forwarder in an unmanaged CPE.
The unmanaged CPE administrator (referred to as administrator) can
host a DoH/DoT forwarder on the unmanaged CPE. This assumes the
following:
o The DoH/DoT server certificate is managed by the entity in-charge
of hosting the DoT/DoH forwarder.
Alternatively, a security service provider can assign a unique
FQDN to the CPE. The DoH/DoT forwarder will act like a private
DoT/DoH server only be accessible from within the home network.
o The DoH/DoT forwarder will either be configured to use the ISP's
or a 3rd party DoH/DoT server.
o The unmanaged CPE will advertise the DoH/DoT forwarder ADN using
DHCP/RA to internal hosts.
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Figure 17 illustrates an example of an unmanaged CPE hosting a
forwarder which connects to a 3rd party DoH/DoT server. In this
example, the DNS information received from the managed CPE (and
therefore from the ISP) is ignored by the Internal CPE hosting the
forwarder.
,--,--,--. ,--,
,' Internal Managed ,-' '- 3rd Party
Host--( Network#A CPE--------CPE------( ISP )--- DNS Server
| `. ,-'| | `-. -' |
| `-'--'--' | |<==DHCP==>|`--' |
| |<==DHCP==>| | |
|<======DHCP=======>| | |
| {RI, @i} | |
|<=====DoT/DoH=====>|<=============DoT/DoH=============>|
Legend:
* @i: IP address of the DNS forwarder hosted in the Internal
CPE.
Figure 17: Example of an Internal CPE Hosting a Forwarder
8. Security Considerations
An attacker can get a domain name, domain-validated public
certificate from a CA, host a DoT/DoH server and claim the best DNS
privacy preservation policy. Also, an attacker within the home
network can use the public IP address, get an 'IP address'-validated
public certificate from a CA, host a DoT/DoH server and claim the
best DNS privacy preservation policy.
Because DHCP/RA messages are not encrypted or protected against
modification in any way, their content can be spoofed or modified by
compromised devices within the home network. An attacker can spoof
the DHCP/RA response to provide the attacker's DoT/DoH server. Note
that such an attacker can launch other attacks as discussed in
Section 22 of [RFC8415]. Furthermore, if the browser or the OS is
pre-configured with a list of DNS servers and some of which perform
malware filtering while others do not, an attacker can prevent
contacting the preferred filtering DNS servers causing a downgrade
attack to a non-filtering DNS server, which the attacker can leverage
to deliver malware.
The use of DoH/DoT also depends on the user's policies. For example,
the user may indicate his/her consent to use (or not) the locally-
discovered DoH/DoT server or request to review human-readable privacy
policy information of a selected DNS server and to assess whether
that DNS server performs DNS-based content filtering (e.g.,
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[I-D.reddy-dprive-dprive-privacy-policy]). The DNS client is assumed
to adhere to these policies. This document does not make any
assumption about the structure of such policies nor mandates specific
requirements. Such policies and their handling is out of scope.
DoH/DoT servers discovered using insecure discovery mechanisms like
DHCP/RA are used by a DNS client if the insecurely discovered DoH/DoT
server is pre-configured in the OS or the browser. Section 6.1
identifies a set of deployment options under which DHCP/RA RI options
can be used.
If the insecurely discovered DoH/DoT server is not pre-configured in
the OS or browser, the client may validate the signatory (e.g.,
cryptographically attested by the ISP). However, as discussed above,
the use of policies to select servers is out of scope of this
document.
DoT/DoH sessions with rogue servers spoofing the IP address of a DNS
server will fail because the DNS client will fail to authenticate
that rogue server based upon PKIX authentication [RFC6125] based upon
the authentication domain name in the Reference Identifier Option.
DNS clients that ignore authentication failures and accept spoofed
certificates will be subject to attacks (e.g., redirect to malicious
servers, intercept sensitive data).
The resolution of redirected domain using Do53 (Section 7.1.2.1) is a
minimal leakage (see Section 6.3 of [RFC8310]). To protect against
DNS-vectored attacks, DNSSEC can be used to ensure the validity of
the received DNS records received. Impersonation of a DoH/DoT
forwarder is prevented by validating the certificate presented by the
DoH/DoT forwarder.
TCP connections received outside the home network MUST be discarded
by the DoH/DoT forwarder in the CPE. This behavior adheres to REQ#8
in [RFC6092]; it MUST apply for both IPv4 and IPv6.
9. IANA Considerations
9.1. DHCPv6 Option
IANA is requested to assign the following new DHCPv6 Option Code in
the registry maintained in: https://www.iana.org/assignments/dhcpv6-
parameters/dhcpv6-parameters.xhtml#dhcpv6-parameters-2.
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+-------+------------------+---------+-------------+----------------+
| Value | Description | Client | Singleton | Reference |
| | | ORO | Option | |
+-------+------------------+---------+-------------+----------------+
| TBA1 | OPTION_V6_DNS_RI | Yes | Yes | [ThisDocument] |
+-------+------------------+---------+-------------+----------------+
9.2. DHCP Option
IANA is requested to assign the following new DHCP Option Code in the
registry maintained in: https://www.iana.org/assignments/bootp-dhcp-
parameters/bootp-dhcp-parameters.xhtml#options.
+------+------------------+-------+----------------+----------------+
| Tag | Name | Data | Meaning | Reference |
| | | Length| | |
+------+------------------+-------+----------------+----------------+
| TBA2 | OPTION_V4_DNS_RI | N | DoT/DoH server | [ThisDocument] |
| | | | authentication | |
| | | | domain name | |
+------+------------------+-------+----------------+----------------+
9.3. RA Option
IANA is requested to assign the following new IPv6 Neighbor Discovery
Option type in the "IPv6 Neighbor Discovery Option Formats" sub-
registry under the "Internet Control Message Protocol version 6
(ICMPv6) Parameters" registry maintained in
http://www.iana.org/assignments/icmpv6-parameters/
icmpv6-parameters.xhtml#icmpv6-parameters-5.
+------+---------------------------------+----------------+
| Type | Description | Reference |
+------+---------------------------------+----------------+
| TBA3 | DNS Reference Identifier Option | [ThisDocument] |
+------+---------------------------------+----------------+
9.4. Service Name
IANA is requested to allocate the following service name from the
registry available at: https://www.iana.org/assignments/service-
names-port-numbers/service-names-port-numbers.xhtml.
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Service Name: doh
Port Number: N/A
Transport Protocol(s): TCP
Description: DNS-over-HTTPS
Assignee: IESG <iesg@ietf.org>
Contact: IETF Chair <chair@ietf.org>
Reference: [ThisDocument]
9.5. Encrypted DNS Types
This document requests IANA to create a new registry called
"Encrypted DNS Types". The initial values of the registery is as
follows:
+-------+----------------------+-----------+
| Value | Description | Reference |
+-------+----------------------+-----------+
| 0 | Any | RFC XXXX |
| 1 | DNS-over-TLS (DoT) | RFC XXXX |
| 2 | DNS-over-HTTPs (DoH) | RFC XXXX |
+-------+----------------------+-----------+
New values are assigned on a First Come, First Served (FCFS) basis
(Section 4.4 of [RFC8126]).
10. Acknowledgements
Many thanks to Christian Jacquenet for the review.
Thanks to Tommy Jensen, Stephen Farrell, Martin Thomson, Vittorio
Bertola, and Iain Sharp for the comments.
Thanks to Mark Nottingham for the feedback on HTTP redirection.
11. References
11.1. Normative References
[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>.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, DOI 10.17487/RFC2132, March 1997,
<https://www.rfc-editor.org/info/rfc2132>.
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[RFC3396] Lemon, T. and S. Cheshire, "Encoding Long Options in the
Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396,
DOI 10.17487/RFC3396, November 2002,
<https://www.rfc-editor.org/info/rfc3396>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>.
[RFC7538] Reschke, J., "The Hypertext Transfer Protocol Status Code
308 (Permanent Redirect)", RFC 7538, DOI 10.17487/RFC7538,
April 2015, <https://www.rfc-editor.org/info/rfc7538>.
[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>.
[RFC8106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
"IPv6 Router Advertisement Options for DNS Configuration",
RFC 8106, DOI 10.17487/RFC8106, March 2017,
<https://www.rfc-editor.org/info/rfc8106>.
[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>.
[RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
Richardson, M., Jiang, S., Lemon, T., and T. Winters,
"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/info/rfc8415>.
[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>.
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11.2. Informative References
[Auto-upgrade]
The Unicode Consortium, "DoH providers: criteria, process
for Chrome", <docs.google.com/document/
d/128i2YTV2C7T6Gr3I-81zlQ-_Lprnsp24qzy_20Z1Psw/edit>.
[DPP] The Wi-Fi Alliance, "Device Provisioning Protocol
Specification", <https://www.wi-fi.org/file/device-
provisioning-protocol-specification>.
[I-D.ietf-dnsop-terminology-ter]
Hoffman, P., "Terminology for DNS Transports and
Location", draft-ietf-dnsop-terminology-ter-01 (work in
progress), February 2020.
[I-D.ietf-dnssd-push]
Pusateri, T. and S. Cheshire, "DNS Push Notifications",
draft-ietf-dnssd-push-25 (work in progress), October 2019.
[I-D.ietf-v6ops-rfc7084-bis]
Palet, J., "Basic Requirements for IPv6 Customer Edge
Routers", draft-ietf-v6ops-rfc7084-bis-04 (work in
progress), June 2017.
[I-D.reddy-dprive-bootstrap-dns-server]
Reddy.K, T., Wing, D., Richardson, M., and M. Boucadair,
"A Bootstrapping Procedure to Discover and Authenticate
DNS-over-TLS and DNS-over-HTTPS Servers", draft-reddy-
dprive-bootstrap-dns-server-08 (work in progress), March
2020.
[I-D.reddy-dprive-dprive-privacy-policy]
Reddy.K, T., Wing, D., Richardson, M., and M. Boucadair,
"DNS Server Privacy Statement and Filtering Policy with
Assertion Token", draft-reddy-dprive-dprive-privacy-
policy-03 (work in progress), March 2020.
[RFC3646] Droms, R., Ed., "DNS Configuration options for Dynamic
Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3646,
DOI 10.17487/RFC3646, December 2003,
<https://www.rfc-editor.org/info/rfc3646>.
[RFC6092] Woodyatt, J., Ed., "Recommended Simple Security
Capabilities in Customer Premises Equipment (CPE) for
Providing Residential IPv6 Internet Service", RFC 6092,
DOI 10.17487/RFC6092, January 2011,
<https://www.rfc-editor.org/info/rfc6092>.
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Internet-Draft DoH/DoT in Home Networks April 2020
[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer
Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
2011, <https://www.rfc-editor.org/info/rfc6125>.
[RFC6731] Savolainen, T., Kato, J., and T. Lemon, "Improved
Recursive DNS Server Selection for Multi-Interfaced
Nodes", RFC 6731, DOI 10.17487/RFC6731, December 2012,
<https://www.rfc-editor.org/info/rfc6731>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC7250] Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J.,
Weiler, S., and T. Kivinen, "Using Raw Public Keys in
Transport Layer Security (TLS) and Datagram Transport
Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250,
June 2014, <https://www.rfc-editor.org/info/rfc7250>.
[RFC7838] Nottingham, M., McManus, P., and J. Reschke, "HTTP
Alternative Services", RFC 7838, DOI 10.17487/RFC7838,
April 2016, <https://www.rfc-editor.org/info/rfc7838>.
[RFC7969] Lemon, T. and T. Mrugalski, "Customizing DHCP
Configuration on the Basis of Network Topology", RFC 7969,
DOI 10.17487/RFC7969, October 2016,
<https://www.rfc-editor.org/info/rfc7969>.
[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>.
[RFC8520] Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage
Description Specification", RFC 8520,
DOI 10.17487/RFC8520, March 2019,
<https://www.rfc-editor.org/info/rfc8520>.
[RFC8555] Barnes, R., Hoffman-Andrews, J., McCarney, D., and J.
Kasten, "Automatic Certificate Management Environment
(ACME)", RFC 8555, DOI 10.17487/RFC8555, March 2019,
<https://www.rfc-editor.org/info/rfc8555>.
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[TR-069] The Broadband Forum, "CPE WAN Management Protocol",
December 2018, <https://www.broadband-
forum.org/technical/download/TR-069.pdf>.
[TS.24008]
3GPP, "Mobile radio interface Layer 3 specification; Core
network protocols; Stage 3 (Release 16)", December 2019,
<http://www.3gpp.org/DynaReport/24008.htm>.
Authors' Addresses
Mohamed Boucadair
Orange
Rennes 35000
France
Email: mohamed.boucadair@orange.com
Tirumaleswar Reddy
McAfee, Inc.
Embassy Golf Link Business Park
Bangalore, Karnataka 560071
India
Email: TirumaleswarReddy_Konda@McAfee.com
Dan Wing
Citrix Systems, Inc.
USA
Email: dwing-ietf@fuggles.com
Neil Cook
Open-Xchange
UK
Email: neil.cook@noware.co.uk
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