RADIUS Extensions for DHCP Configured Services
draft-ietf-opsawg-add-encrypted-dns-10

opsawg                                                      M. Boucadair
Internet-Draft                                                    Orange
Updates: 4014 (if approved)                                     T. Reddy
Intended status: Standards Track                                   Nokia
Expires: 27 August 2023                                         A. DeKok
                                                              FreeRADIUS
                                                        23 February 2023

             RADIUS Extensions for DHCP Configured Services
                 draft-ietf-opsawg-add-encrypted-dns-10

Abstract

   This document specifies two new Remote Authentication Dial-In User
   Service (RADIUS) attributes that carry DHCP options.  Even if the
   specification was initially motivated by the configuration of
   encrypted DNS resolvers, the specification is generic and can be
   applicable to any service that relies upon DHCP.  Both DHCPv4 and
   DHCPv6 configured services are covered.

   Also, this document updates RFC 4014 by relaxing a constraint on
   permitted RADIUS Attributes in the RADIUS Attributes DHCP suboption.

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
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   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
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   This Internet-Draft will expire on 27 August 2023.

Copyright Notice

   Copyright (c) 2023 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  DHCP Options RADIUS Attributes  . . . . . . . . . . . . . . .   4
     3.1.  DHCPv6-Options Attribute  . . . . . . . . . . . . . . . .   5
     3.2.  DHCPv4-Options Attribute  . . . . . . . . . . . . . . . .   6
   4.  Passing DHCP Options RADIUS Attributes to DHCP Servers  . . .   7
     4.1.  Context . . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Updates to RFC 4014 . . . . . . . . . . . . . . . . . . .   7
       4.2.1.  Section 3 of RFC 4014 . . . . . . . . . . . . . . . .   8
       4.2.2.  Section 4 of RFC 4014 . . . . . . . . . . . . . . . .   8
   5.  Applicability to Encrypted DNS Provisioning . . . . . . . . .   9
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   7.  Table of Attributes . . . . . . . . . . . . . . . . . . . . .  11
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
     8.1.  New RADIUS Attributes . . . . . . . . . . . . . . . . . .  12
     8.2.  New RADIUS Attribute Permitted in DHCPv6 RADIUS Option  .  12
     8.3.  RADIUS Attributes Permitted in RADIUS Attributes DHCP
           Sub-option  . . . . . . . . . . . . . . . . . . . . . . .  12
     8.4.  DHCP Options Permitted in the RADIUS DHCP*-Options
           Attribute . . . . . . . . . . . . . . . . . . . . . . . .  13
       8.4.1.  DHCPv6  . . . . . . . . . . . . . . . . . . . . . . .  13
       8.4.2.  DHCPv4  . . . . . . . . . . . . . . . . . . . . . . .  14
       8.4.3.  Guidelines for the Designated Experts . . . . . . . .  14
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  15
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  15
     10.2.  Informative References . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

   In the context of broadband services, Internet Service Providers
   (ISPs) usually provide DNS resolvers to their customers.  To that
   aim, ISPs deploy dedicated mechanisms (e.g., DHCP [RFC2132]
   [RFC8415], IPv6 Router Advertisement [RFC4861]) to advertise a list
   of DNS recursive servers to their customers.  Typically, the
   information used to populate DHCP messages and/or IPv6 Router

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   Advertisements relies upon specific Remote Authentication Dial-In
   User Service (RADIUS) [RFC2865] attributes, such as the DNS-Server-
   IPv6-Address Attribute specified in [RFC6911].

   With the advent of encrypted DNS (e.g., DNS-over-HTTPS (DoH)
   [RFC8484], DNS-over-TLS (DoT) [RFC7858], or DNS-over-QUIC (DoQ)
   [RFC9250]), additional means are required to provision hosts with
   network-designated encrypted DNS.  To fill that void,
   [I-D.ietf-add-dnr] leverages existing protocols such as DHCP to
   provide hosts with the required information to connect to an
   encrypted DNS resolver.  However, there are no RADIUS attributes that
   can be used to populate the discovery messages discussed in
   [I-D.ietf-add-dnr].  The same concern is likely to be encountered for
   future services that are configured using DHCP.

   This document specifies two new RADIUS attributes: DHCPv6-Options
   (Section 3.1) and DHCPv4-Options (Section 3.2) Attributes.  These
   attributes can include DHCP options that are listed under the IANA
   registries that are created in Sections 8.4.1 and 8.4.2.  These two
   attributes are specified in order to accommodate both IPv4 and IPv6
   deployment contexts while taking into account the constraints in
   Section 3.4 of [RFC6158].

   The mechanism specified in this document is a generic mechanism and
   might be employed in network scenarios where the DHCP server and the
   RADIUS client are located in the same device.  The new attributes can
   also be used in deployments that rely upon the mechanisms defined in
   [RFC4014] or [RFC7037], which allow a DHCP relay agent that is
   collocated with a RADIUS client to pass attributes obtained from a
   RADIUS server to a DHCP server.  However, an update to [RFC4014] is
   required so that a DHCP relay agent can pass the DHCPv4-Options
   Attribute obtained from a RADIUS server to a DHCP server (Section 4).

   DHCP options that are included in the new RADIUS attributes can be
   controlled by a deployment specific policy.  Discussing such as
   policy is out of scope.

   This document adheres to [RFC8044] for defining the new attributes.

   A sample deployment usage of the DHCPv6-Options and DHCPv4-Options
   RADIUS attributes is described in Section 5.

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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 [RFC2865], [RFC8415],
   and [RFC8499].  The following additional terms are used:

   DHCP:  refers to both DHCPv4 [RFC2132] and DHCPv6 [RFC8415].

   Encrypted DNS:  refers to a scheme where DNS exchanges are
      transported over an encrypted channel.  Examples of encrypted DNS
      are DoT, DoH, and DoQ.

   Encrypted DNS resolver:  refers to a resolver (Section 6 of
      [RFC8499]) that supports encrypted DNS.

   DHCP*-Options:  refers to DHCPv4-Options and DHCPv6-Options
      Attributes (Section 3).

3.  DHCP Options RADIUS Attributes

   This section specifies two new RADIUS attributes for RADIUS clients
   and servers to exchange DHCP-encoded data.  This data is then used to
   feed the DHCP procedure between a DHCP client and a DHCP server.

   Both DHCPv4-Options and DHCPv6-Options Attributes use the "Long
   Extended Type" format (Section 2.2 of [RFC6929]).  The description of
   the fields is provided in Sections 3.1 and 3.2.

   These attributes use the "Long Extended Type" format in order to
   permit the transport of attributes encapsulating more than 253 octets
   of data.  DHCP options that can be included in the DHCP*-Options
   RADIUS attributes are limited by the maximum packet size of 4096
   bytes (Section 3 of [RFC2865]).  In order to accommodate deployments
   with large DHCP options, RADIUS implementations are RECOMMENDED to
   support a packet size up to 65535 bytes.  Such a recommendation can
   be met if RADIUS implementations support a mechanism that relaxes the
   4096 bytes limit (e.g., [RFC7499] or [RFC7930]).

   The value fields of DHCP*-Options Attributes are encoded in clear and
   not encrypted as, for example, Tunnel-Password Attribute [RFC2868].

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   RADIUS implementations may support a configuration parameter to
   control the DHCP options that can be included in a DHCP*-Options
   RADIUS attribute.  Likewise, DHCP server implementations may support
   a configuration parameter to control the permitted DHCP options in a
   DHCP*-Options RADIUS attribute.

   For ease of administrator configuration, the RADIUS server SHOULD
   expose the DHCP options and allow administrators to configure them,
   instead of requiring them to be entered as opaque data.

   RADIUS supplied data is specific configuration data that is returned
   as a function of authentication and authorization checks.  As such,
   absent any explicit configuration on the DHCP server, RADIUS supplied
   data by means of DHCP*-Options Attributes take precedence over any
   local configuration.

   These attributes are defined with globally unique names.  The naming
   of the attributes follows the guidelines in Section 2.7.1 of
   [RFC6929].

3.1.  DHCPv6-Options Attribute

   This attribute is of type "string" as defined in Section 3.5 of
   [RFC8044].

   The DHCPv6-Options Attribute MAY appear in a RADIUS Access-Accept
   packet.  It MAY also appear in a RADIUS Access-Request packet as a
   hint to the RADIUS server to indicate a preference.  However, the
   server is not required to honor such a preference.

   The DHCPv6-Options Attribute MAY appear in a RADIUS CoA-Request
   packet.

   The DHCPv6-Options Attribute MAY appear in a RADIUS Accounting-
   Request packet.

   The DHCPv6-Options Attribute MUST NOT appear in any other RADIUS
   packet.

   The DHCPv6-Options Attribute is structured as follows:

   Type

      245

   Length

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      This field indicates the total length, in octets, of all fields of
      this attribute, including the Type, Length, Extended-Type, and
      "Value".

   Extended-Type

      TBA1 (see Section 8.1).

   Value

      This field contains a list of DHCPv6 options (Section 21 of
      [RFC8415]).  Multiple instances of the same DHCPv6 option MAY be
      included.  If an option appears multiple times, each instance is
      considered separate and the data areas of the options MUST NOT be
      concatenated or otherwise combined.  Consistent with Section 17 of
      [RFC7227], this document does not impose any option order when
      multiple options are present.

      Permitted DHCPv6 options in the DHCPv6-Options Attribute are
      maintained by IANA in the registry created in Section 8.4.1.

   The DHCPv6-Options Attribute is associated with the following
   identifier: 245.TBA1.

3.2.  DHCPv4-Options Attribute

   This attribute is of type "string" as defined in Section 3.5 of
   [RFC8044].

   The DHCPv4-Options Attribute MAY appear in a RADIUS Access-Accept
   packet.  It MAY also appear in a RADIUS Access-Request packet as a
   hint to the RADIUS server to indicate a preference.  However, the
   server is not required to honor such a preference.

   The DHCPv4-Options Attribute MAY appear in a RADIUS CoA-Request
   packet.

   The DHCPv4-Options Attribute MAY appear in a RADIUS Accounting-
   Request packet.

   The DHCPv4-Options Attribute MUST NOT appear in any other RADIUS
   packet.

   The DHCPv4-Options Attribute is structured as follows:

   Type

      245

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   Length

      This field indicates the total length, in octets, of all fields of
      this attribute, including the Type, Length, Extended-Type, and
      "Value".

   Extended-Type

      TBA2 (see Section 8.1).

   Value

      This field contains a list of DHCPv4 options.  Multiple instances
      of the same DHCPv4 option MAY be included, especially for
      concatenation-requiring options that exceed the maximum DHCPv4
      option size of 255 octets.  The mechanism specified in [RFC3396]
      MUST be used for splitting and concatenating the instances of a
      concatenation-requiring option.

      Permitted DHCPv4 options in the DHCPv4-Options Attribute are
      maintained by IANA in the registry created in Section 8.4.2.

   The DHCPv4-Options Attribute is associated with the following
   identifier: 245.TBA2.

4.  Passing DHCP Options RADIUS Attributes to DHCP Servers

4.1.  Context

   The RADIUS Attributes suboption [RFC4014] enables a DHCPv4 relay
   agent to pass identification and authorization attributes received
   during RADIUS authentication to a DHCPv4 server.  However, [RFC4014]
   defines a frozen set of RADIUS attributes that can be included in
   such a suboption.  This limitation is suboptimal in contexts where
   new services are deployed (e.g., support of encrypted DNS
   [I-D.ietf-add-dnr]).

   Section 4.2 updates [RFC4014] by relaxing that constraint and
   allowing to tag additional RADIUS attributes as permitted in the
   RADIUS Attributes DHCP suboption.  Section 8.3 creates a new IANA
   registry to maintain the set of permitted attributes in the RADIUS
   Attributes DHCP suboption.

4.2.  Updates to RFC 4014

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4.2.1.  Section 3 of RFC 4014

   This document updates Section 3 of [RFC4014] as follows:

   OLD:
      To avoid dependencies between the address allocation and other
      state information between the RADIUS server and the DHCP server,
      the DHCP relay agent SHOULD include only the attributes in the
      table below in an instance of the RADIUS Attributes suboption.
      The table, based on the analysis in RFC 3580 [8], lists attributes
      that MAY be included:

                 #   Attribute
               ---   ---------
                 1   User-Name (RFC 2865 [3])
                 6   Service-Type (RFC 2865)
                26   Vendor-Specific (RFC 2865)
                27   Session-Timeout (RFC 2865)
                88   Framed-Pool (RFC 2869)
               100   Framed-IPv6-Pool (RFC 3162 [7])

   NEW:
      To avoid dependencies between the address allocation and other
      state information between the RADIUS server and the DHCP server,
      the DHCP relay agent SHOULD include only the attributes in the
      IANA-maintained registry (Section 8.3 of [This-Document]) in an
      instance of the RADIUS Attributes suboption.

4.2.2.  Section 4 of RFC 4014

   This document updates Section 4 of [RFC4014] as follows:

   OLD:
      If the relay agent relays RADIUS attributes not included in the
      table in Section 4, the DHCP server SHOULD ignore them.

   NEW:
      If the relay agent relays RADIUS attributes not included in the
      IANA-maintained registry (Section 8.3 of [This-Document]), the
      DHCP server SHOULD ignore them.

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5.  Applicability to Encrypted DNS Provisioning

   Typical deployment scenarios are similar to those described, for
   instance, in Section 2 of [RFC6911].  For illustration purposes,
   Figure 1 shows an example where a Customer Premises Equipment (CPE)
   is provided with an encrypted DNS resolver.  This example assumes
   that the Network Access Server (NAS) embeds both RADIUS client and
   DHCPv6 server capabilities.

   +-------------+           +-------------+             +-------+
   |     CPE     |           |     NAS     |             |  AAA  |
   |DHCPv6 client|           |DHCPv6 server|             |Server |
   |             |           |RADIUS client|             |       |
   +------+------+           +------+------+             +---+---+
          |                         |                        |
          o-----DHCPv6 Solicit----->|                        |
          |                         o----Access-Request ---->|
          |                         |                        |
          |                         |<----Access-Accept------o
          |                         |     DHCPv6-Options     |
          |<----DHCPv6 Advertise----o    (OPTION_V6_DNR)     |
          |     (OPTION_V6_DNR)     |                        |
          |                         |                        |
          o-----DHCPv6 Request----->|                        |
          |                         |                        |
          |<------DHCPv6 Reply------o                        |
          |     (OPTION_V6_DNR)     |                        |
          |                         |                        |

                   DHCPv6                     RADIUS

         Figure 1: An Example of RADIUS IPv6 Encrypted DNS Exchange

   Upon receipt of the DHCPv6 Solicit message from a CPE, the NAS sends
   a RADIUS Access-Request message to the Authentication, Authorization,
   and Accounting (AAA) server.  Once the AAA server receives the
   request, it replies with an Access-Accept message (possibly after
   having sent a RADIUS Access-Challenge message and assuming the CPE is
   entitled to connect to the network) that carries a list of parameters
   to be used for this session, and which include the encrypted DNS
   information.  Such an information is encoded as OPTION_V6_DNR (144)
   instances ([I-D.ietf-add-dnr]) in the DHCPv6-Options RADIUS
   attribute.  These instances are then used by the NAS to complete the
   DHCPv6 procedure that the CPE initiated to retrieve information about
   the encrypted DNS service to use.  The Discovery of Network-
   designated Resolvers (DNR) procedure defined in [I-D.ietf-add-dnr] is
   then followed between the DHCPv6 client and the DHCPv6 server.

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   Should any encrypted DNS-related information (e.g., Authentication
   Domain Name (ADN), IPv6 address) change, the RADIUS server sends a
   RADIUS Change-of-Authorization (CoA) message [RFC5176] that carries
   the DHCPv6-Options Attribute with the updated OPTION_V6_DNR
   information to the NAS.  Once that message is received and validated
   by the NAS, it replies with a RADIUS CoA ACK message.  The NAS
   replaces the old encrypted DNS resolver information with the new one
   and sends a DHCPv6 Reconfigure message which leads the DHCPv6 client
   to initiate a Renew/Reply message exchange with the DHCPv6 server.

   In deployments where the NAS behaves as a DHCPv6 relay agent, the
   procedure discussed in Section 3 of [RFC7037] can be followed.  To
   that aim, Section 8.2 updates the "RADIUS Attributes Permitted in
   DHCPv6 RADIUS Option" registry ([DHCP-RADIUS]).

   Figure 2 shows another example where a CPE is provided with an
   encrypted DNS resolver, but the CPE uses DHCPv4 to retrieve its
   encrypted DNS resolver.

   +-------------+           +-------------+             +-------+
   |     CPE     |           |     NAS     |             |  AAA  |
   |DHCPv4 client|           |DHCPv4 server|             |Server |
   |             |           |RADIUS client|             |       |
   +------+------+           +------+------+             +---+---+
          |                         |                        |
          o------DHCPDISCOVER------>|                        |
          |                         o----Access-Request ---->|
          |                         |                        |
          |                         |<----Access-Accept------o
          |                         |     DHCPv4_Options     |
          |<-----DHCPOFFER----------o    (OPTION_V4_DNR)     |
          |     (OPTION_V4_DNR)     |                        |
          |                         |                        |
          o-----DHCPREQUEST-------->|                        |
          |     (OPTION_V4_DNR)     |                        |
          |                         |                        |
          |<-------DHCPACK----------o                        |
          |     (OPTION_V4_DNR)     |                        |
          |                         |                        |

                  DHCPv4                      RADIUS

         Figure 2: An Example of RADIUS IPv4 Encrypted DNS Exchange

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   Other deployment scenarios can be envisaged, such as returning
   customized service parameters (e.g., different DoH URI Templates) as
   a function of the service/policies/preferences that are set by a
   network administrator.  How an administrator indicates its
   service/policies/preferences to an AAA server is out of scope.

6.  Security Considerations

   RADIUS-related security considerations are discussed in [RFC2865].

   This document targets deployments where a trusted relationship is in
   place between the RADIUS client and server with communication
   optionally secured by IPsec or Transport Layer Security (TLS)
   [RFC6614].

   Security considerations specific to the DHCP options that are carried
   in RADIUS are discussed in relevant documents that specify these
   options.  For example, security considerations (including traffic
   theft) are discussed in Section 7 of [I-D.ietf-add-dnr].

   The considerations discussed in Section 7 of [RFC4014] and Section 8
   of [RFC7037] should be taken into account in deployments where DHCP
   relay agents pass the DHCP*-Options Attributes to DHCP servers.

7.  Table of Attributes

   The following table provides a guide as what type of RADIUS packets
   that may contain these attributes, and in what quantity.

   Access- Access- Access-  Challenge Acct.    #        Attribute
   Request Accept  Reject             Request
    0+      0+      0        0         0+      245.TBA1 DHCPv6-Options
    0+      0+      0        0         0+      245.TBA2 DHCPv4-Options

   CoA-Request CoA-ACK CoA-NACK #        Attribute
     0+          0       0      245.TBA1 DHCPv6-Options
     0+          0       0      245.TBA2 DHCPv4-Options

   The following table defines the meaning of the above table entries:

   0  This attribute MUST NOT be present in packet.
   0+ Zero or more instances of this attribute MAY be present in packet.

8.  IANA Considerations

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8.1.  New RADIUS Attributes

   IANA is requested to assign two new RADIUS attribute types from the
   IANA registry "Radius Attribute Types" [RADIUS-Types]:

         +==========+================+===========+===============+
         | Value    | Description    | Data Type | Reference     |
         +==========+================+===========+===============+
         | 245.TBA1 | DHCPv6-Options | string    | This-Document |
         +----------+----------------+-----------+---------------+
         | 245.TBA2 | DHCPv4-Options | string    | This-Document |
         +----------+----------------+-----------+---------------+

                       Table 1: New RADIUS Attributes

8.2.  New RADIUS Attribute Permitted in DHCPv6 RADIUS Option

   IANA is requested to add the following entry to the "RADIUS
   Attributes Permitted in DHCPv6 RADIUS Option" subregistry in the
   "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)" registry
   [DHCP-RADIUS]:

              +===========+================+===============+
              | Type Code | Attribute      | Reference     |
              +===========+================+===============+
              | 245.TBA1  | DHCPv6-Options | This-Document |
              +-----------+----------------+---------------+

                Table 2: New RADIUS Attribute Permitted in
                           DHCPv6 RADIUS Option

8.3.  RADIUS Attributes Permitted in RADIUS Attributes DHCP Sub-option

   IANA is requested to create a new sub-registry entitled "RADIUS
   Attributes Permitted in RADIUS Attributes Sub-option" in the "Dynamic
   Host Configuration Protocol (DHCP) and Bootstrap Protocol (BOOTP)
   Parameters" registry [BOOTP].

   The allocation policy of this new sub-registry is Expert Review
   (Section 4.5 of [RFC8126]).  Designated experts should carefully
   consider the security implications of allowing the relay agent to
   include new RADIUS attributes to this registry.  Additional
   considerations are provided in Section 8.4.3.

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   The initial content of this sub-registry is listed in Table 3.  The
   reference may include the document that registers or specifies the
   Attribute.

             +===========+==================+===============+
             | Type Code | Attribute        | Reference     |
             +===========+==================+===============+
             | 1         | User-Name        | [RFC2865]     |
             +-----------+------------------+---------------+
             | 6         | Service-Type     | [RFC2865]     |
             +-----------+------------------+---------------+
             | 26        | Vendor-Specific  | [RFC2865]     |
             +-----------+------------------+---------------+
             | 27        | Session-Timeout  | [RFC2865]     |
             +-----------+------------------+---------------+
             | 88        | Framed-Pool      | [RFC2869]     |
             +-----------+------------------+---------------+
             | 100       | Framed-IPv6-Pool | [RFC3162]     |
             +-----------+------------------+---------------+
             | 245.TBA2  | DHCPv4-Options   | This-Document |
             +-----------+------------------+---------------+

                 Table 3: RADIUS Attributes Permitted in
                     RADIUS Attributes DHCP Suboption

8.4.  DHCP Options Permitted in the RADIUS DHCP*-Options Attribute

8.4.1.  DHCPv6

   IANA is requested to create a new sub-registry entitled "DHCPv6
   Options Permitted in the RADIUS DHCPv6-Options Attribute" in the
   "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)" registry
   [DHCP-RADIUS].

   The registration policy for this new sub-registry is Expert Review
   (Section 4.5 of [RFC8126]).  See more details in Section 8.4.3.

   The initial content of this sub-registry is listed in Table 4.  The
   Value and Description fields echo those of [DHCPv6].  The reference
   may include the document that registers the option or the document
   that specifies the option.

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                 +=======+===============+===============+
                 | Value | Description   | Reference     |
                 +=======+===============+===============+
                 | 144   | OPTION_V6_DNR | This-Document |
                 +-------+---------------+---------------+

                      Table 4: Initial DHCPv6 Options
                          Permitted in the RADIUS
                          DHCPv6-Options Attribute

8.4.2.  DHCPv4

   IANA is requested to create a new sub-registry entitled "DHCP Options
   Permitted in the RADIUS DHCPv4-Options Attribute" in the "Dynamic
   Host Configuration Protocol (DHCP) and Bootstrap Protocol (BOOTP)
   Parameters" registry [BOOTP].

   The registration policy for this new sub-registry is Expert Review
   (Section 4.5 of [RFC8126]).  See more details in Section 8.4.3.

   The initial content of this sub-registry is listed in Table 5.  The
   Tag and Name fields echo those of [BOOTP].  The reference may include
   the document that registers the option or the document that specifies
   the option.

                  +=====+===============+===============+
                  | Tag | Name          | Reference     |
                  +=====+===============+===============+
                  | 162 | OPTION_V4_DNR | This-Document |
                  +-----+---------------+---------------+

                      Table 5: Initial DHCPv4 Options
                          Permitted in the RADIUS
                          DHCPv4-Options Attribute

8.4.3.  Guidelines for the Designated Experts

   It is suggested that multiple designated experts be appointed for
   registry change requests.

   Criteria that should be applied by the designated experts include
   determining whether the proposed registration duplicates existing
   entries and whether the registration description is clear and fits
   the purpose of this registry.

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   Registration requests are to be sent to radius-dhcp-review@ietf.org
   and are evaluated within a three-week review period on the advice of
   one or more designated experts.  Within the review period, the
   designated experts will either approve or deny the registration
   request, communicating this decision to the review list and IANA.
   Denials should include an explanation and, if applicable, suggestions
   as to how to make the request successful.

9.  Acknowledgements

   Thanks to Christian Jacquenet, Neil Cook, Joe Clarke, Qin Wu, Dirk
   von-Hugo, Tom Petch, and Chongfeng Xie for the review and
   suggestions.

   Thanks to Ben Schwartz and Bernie Volz for the comments.

   Thanks to Rob Wilton for the careful AD review.

   Thanks to Ralf Weber for the dnsdir review and Robert Sparks for
   genart review.

10.  References

10.1.  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>.

   [RFC2865]  Rigney, C., Willens, S., Rubens, A., and W. Simpson,
              "Remote Authentication Dial In User Service (RADIUS)",
              RFC 2865, DOI 10.17487/RFC2865, June 2000,
              <https://www.rfc-editor.org/info/rfc2865>.

   [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>.

   [RFC4014]  Droms, R. and J. Schnizlein, "Remote Authentication Dial-
              In User Service (RADIUS) Attributes Suboption for the
              Dynamic Host Configuration Protocol (DHCP) Relay Agent
              Information Option", RFC 4014, DOI 10.17487/RFC4014,
              February 2005, <https://www.rfc-editor.org/info/rfc4014>.

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   [RFC6158]  DeKok, A., Ed. and G. Weber, "RADIUS Design Guidelines",
              BCP 158, RFC 6158, DOI 10.17487/RFC6158, March 2011,
              <https://www.rfc-editor.org/info/rfc6158>.

   [RFC6929]  DeKok, A. and A. Lior, "Remote Authentication Dial In User
              Service (RADIUS) Protocol Extensions", RFC 6929,
              DOI 10.17487/RFC6929, April 2013,
              <https://www.rfc-editor.org/info/rfc6929>.

   [RFC8044]  DeKok, A., "Data Types in RADIUS", RFC 8044,
              DOI 10.17487/RFC8044, January 2017,
              <https://www.rfc-editor.org/info/rfc8044>.

   [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>.

   [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>.

10.2.  Informative References

   [BOOTP]    IANA, "Dynamic Host Configuration Protocol (DHCP) and
              Bootstrap Protocol (BOOTP) Parameters",
              <https://www.iana.org/assignments/bootp-dhcp-parameters/
              bootp-dhcp-parameters.xhtml>.

   [DHCP-RADIUS]
              IANA, "Dynamic Host Configuration Protocol for IPv6
              (DHCPv6)", <https://www.iana.org/assignments/dhcpv6-
              parameters/dhcpv6-parameters.xhtml>.

   [DHCPv6]   IANA, "Dynamic Host Configuration Protocol for IPv6
              (DHCPv6), Option Codes",
              <https://www.iana.org/assignments/dhcpv6-parameters/
              dhcpv6-parameters.xhtml#dhcpv6-parameters-2>.

   [I-D.ietf-add-dnr]
              Boucadair, M., Reddy.K, T., Wing, D., Cook, N., and T.
              Jensen, "DHCP and Router Advertisement Options for the

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              Discovery of Network-designated Resolvers (DNR)", Work in
              Progress, Internet-Draft, draft-ietf-add-dnr-13, 13 August
              2022, <https://datatracker.ietf.org/doc/html/draft-ietf-
              add-dnr-13>.

   [RADIUS-Types]
              IANA, "RADIUS Types",
              <http://www.iana.org/assignments/radius-types>.

   [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>.

   [RFC2868]  Zorn, G., Leifer, D., Rubens, A., Shriver, J., Holdrege,
              M., and I. Goyret, "RADIUS Attributes for Tunnel Protocol
              Support", RFC 2868, DOI 10.17487/RFC2868, June 2000,
              <https://www.rfc-editor.org/info/rfc2868>.

   [RFC2869]  Rigney, C., Willats, W., and P. Calhoun, "RADIUS
              Extensions", RFC 2869, DOI 10.17487/RFC2869, June 2000,
              <https://www.rfc-editor.org/info/rfc2869>.

   [RFC3162]  Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6",
              RFC 3162, DOI 10.17487/RFC3162, August 2001,
              <https://www.rfc-editor.org/info/rfc3162>.

   [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>.

   [RFC5176]  Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
              Aboba, "Dynamic Authorization Extensions to Remote
              Authentication Dial In User Service (RADIUS)", RFC 5176,
              DOI 10.17487/RFC5176, January 2008,
              <https://www.rfc-editor.org/info/rfc5176>.

   [RFC6614]  Winter, S., McCauley, M., Venaas, S., and K. Wierenga,
              "Transport Layer Security (TLS) Encryption for RADIUS",
              RFC 6614, DOI 10.17487/RFC6614, May 2012,
              <https://www.rfc-editor.org/info/rfc6614>.

   [RFC6911]  Dec, W., Ed., Sarikaya, B., Zorn, G., Ed., Miles, D., and
              B. Lourdelet, "RADIUS Attributes for IPv6 Access
              Networks", RFC 6911, DOI 10.17487/RFC6911, April 2013,
              <https://www.rfc-editor.org/info/rfc6911>.

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   [RFC7037]  Yeh, L. and M. Boucadair, "RADIUS Option for the DHCPv6
              Relay Agent", RFC 7037, DOI 10.17487/RFC7037, October
              2013, <https://www.rfc-editor.org/info/rfc7037>.

   [RFC7227]  Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and
              S. Krishnan, "Guidelines for Creating New DHCPv6 Options",
              BCP 187, RFC 7227, DOI 10.17487/RFC7227, May 2014,
              <https://www.rfc-editor.org/info/rfc7227>.

   [RFC7499]  Perez-Mendez, A., Ed., Marin-Lopez, R., Pereniguez-Garcia,
              F., Lopez-Millan, G., Lopez, D., and A. DeKok, "Support of
              Fragmentation of RADIUS Packets", RFC 7499,
              DOI 10.17487/RFC7499, April 2015,
              <https://www.rfc-editor.org/info/rfc7499>.

   [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>.

   [RFC7930]  Hartman, S., "Larger Packets for RADIUS over TCP",
              RFC 7930, DOI 10.17487/RFC7930, August 2016,
              <https://www.rfc-editor.org/info/rfc7930>.

   [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>.

   [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>.

Authors' Addresses

   Mohamed Boucadair
   Orange
   35000 Rennes
   France
   Email: mohamed.boucadair@orange.com

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   Tirumaleswar Reddy
   Nokia
   India
   Email: kondtir@gmail.com

   Alan DeKok
   FreeRADIUS
   Email: aland@freeradius.org

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