



Internet Engineering Task Force (IETF)                      M. Boucadair
Request for Comments: 9445                                        Orange
Updates: 4014                                                 T. Reddy.K
Category: Standards Track                                          Nokia
ISSN: 2070-1721                                                 A. DeKok
                                                              FreeRADIUS
                                                             August 2023


             RADIUS Extensions for DHCP-Configured Services

Abstract

   This document specifies two new Remote Authentication Dial-In User
   Service (RADIUS) attributes that carry DHCP options.  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 is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9445.

Copyright Notice

   Copyright (c) 2023 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 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.  Terminology
   3.  RADIUS DHCP Options Attributes
     3.1.  DHCPv6-Options Attribute
     3.2.  DHCPv4-Options Attribute
   4.  Passing RADIUS DHCP Options Attributes by DHCP Relay Agents to
           DHCP Servers
     4.1.  Context
     4.2.  Updates to RFC 4014
       4.2.1.  Section 3 of RFC 4014
       4.2.2.  Section 4 of RFC 4014
   5.  An Example: Applicability to Encrypted DNS Provisioning
   6.  Security Considerations
   7.  Table of Attributes
   8.  IANA Considerations
     8.1.  New RADIUS Attributes
     8.2.  New RADIUS Attribute Permitted in DHCPv6 RADIUS Option
     8.3.  RADIUS Attributes Permitted in RADIUS Attributes DHCP
           Suboption
     8.4.  DHCP Options Permitted in the RADIUS DHCP*-Options
           Attributes
       8.4.1.  DHCPv6
       8.4.2.  DHCPv4
       8.4.3.  Guidelines for the Designated Experts
   9.  References
     9.1.  Normative References
     9.2.  Informative References
   Acknowledgements
   Authors' Addresses

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]
   and 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 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, [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 [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).  These attributes can
   include DHCP options that are listed in the "DHCPv6 Options Permitted
   in the RADIUS DHCPv6-Options Attribute" registry (Section 8.4.1) and
   the "DHCP Options Permitted in the RADIUS DHCPv4-Options Attribute"
   registry (Section 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 a policy
   is out of scope.

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

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

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 the DHCPv4-Options and DHCPv6-Options
      Attributes (Section 3).

3.  RADIUS DHCP Options 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 the 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 RADIUS DHCP*-
   Options 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
   limit of 4096 bytes (e.g., the mechanisms described in [RFC7499] or
   [RFC7930]).

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

   RADIUS implementations may support a configuration parameter to
   control the DHCP options that can be included in a RADIUS DHCP*-
   Options Attribute.  Likewise, DHCP server implementations may support
   a configuration parameter to control the permitted DHCP options in a
   RADIUS DHCP*-Options Attribute.  Absent explicit configuration,
   RADIUS implementations and DHCP server implementations SHOULD ignore
   non-permitted DHCP options received in a RADIUS DHCP*-Options
   Attribute.

   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 the 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].  Invalid attributes are handled as per Section 2.8 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
      This field indicates the total length, in octets, of all fields of
      this attribute, including the Type, Length, Extended-Type, and
      Value fields.

   Extended-Type
      3 (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.

      The permitted DHCPv6 options are listed in the "DHCPv6 Options
      Permitted in the RADIUS DHCPv6-Options Attribute" registry
      (Section 8.4.1).

   The DHCPv6-Options Attribute is associated with the following
   identifier: 245.3.

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

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

   Extended-Type
      4 (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.

      The permitted DHCPv4 options are listed in the "DHCP Options
      Permitted in the RADIUS DHCPv4-Options Attribute" registry
      (Section 8.4.2).

   The DHCPv4-Options Attribute is associated with the following
   identifier: 245.4.

4.  Passing RADIUS DHCP Options Attributes by DHCP Relay Agents to DHCP
    Servers

4.1.  Context

   The RADIUS Attributes DHCP 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 [DNR]).

   Section 4.2 updates [RFC4014] by relaxing that constraint and
   allowing additional RADIUS attributes to be tagged as permitted in
   the RADIUS Attributes DHCP suboption.  The permitted attributes are
   registered in the new "RADIUS Attributes Permitted in RADIUS
   Attributes DHCP Suboption" registry (Section 8.3).

4.2.  Updates to RFC 4014


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 only include the attributes in the
   |  "RADIUS Attributes Permitted in RADIUS Attributes DHCP Suboption"
   |  registry (Section 8.3 of [RFC9445]) in an instance of the RADIUS
   |  Attributes DHCP suboption.  The DHCP relay agent may support a
   |  configuration parameter to control the attributes in a RADIUS
   |  Attributes DHCP 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
   |  "RADIUS Attributes Permitted in RADIUS Attributes DHCP Suboption"
   |  registry (Section 8.3 of [RFC9445]) and explicit configuration is
   |  absent, the DHCP server SHOULD ignore them.

5.  An Example: 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, which includes the encrypted DNS
   information.  Such information is encoded as OPTION_V6_DNR (144)
   instances [DNR] in the RADIUS DHCPv6-Options 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 [DNR] is then followed between the DHCPv6
   client and the DHCPv6 server.

   Should any encrypted DNS-related information (e.g., Authentication
   Domain Name (ADN) and 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, the "RADIUS Attributes Permitted in DHCPv6 RADIUS Option"
   registry has been updated (Section 8.2).  CoA-Requests can be used
   following the procedure specified in [RFC6977].

   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

   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, and preferences that are set by
   a network administrator.  How an administrator indicates its service,
   policies, and preferences to a AAA server is out of scope.

6.  Security Considerations

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

   DHCPv6-related security issues are discussed in Section 22 of
   [RFC8415], while DHCPv4-related security issues are discussed in
   Section 7 of [RFC2131].  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 [DNR].

   RADIUS servers have conventionally tolerated the input of arbitrary
   data via the "string" data type (Section 3.5 of [RFC8044]).  This
   practice allows RADIUS servers to support newer standards without
   software upgrades, by allowing administrators to manually create
   complex attribute content and then pass that content to a RADIUS
   server as opaque strings.  While this practice is useful, it is
   RECOMMENDED that RADIUS servers that implement the present
   specification are updated to understand the format and encoding of
   DHCP options.  Administrators can thus enter the DHCP options as
   options instead of manually encoded opaque strings.  This
   recommendation increases security and interoperability by ensuring
   that the options are encoded correctly.  It also increases usability
   for administrators.

   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.
   Additional considerations specific to the use of Reconfigure messages
   are discussed in Section 9 of [RFC6977].

7.  Table of Attributes

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

   +=============+=======+=========+===========+=====+================+
   | Access-     |Access-| Access- | Challenge |#    | Attribute      |
   | Request     |Accept | Reject  |           |     |                |
   +=============+=======+=========+===========+=====+================+
   | 0+          |0+     | 0       | 0         |245.3| DHCPv6-Options |
   +-------------+-------+---------+-----------+-----+----------------+
   | 0+          |0+     | 0       | 0         |245.4| DHCPv4-Options |
   +=============+=======+=========+===========+=====+================+
   | Accounting- |CoA-   | CoA-ACK | CoA-NACK  |#    | Attribute      |
   | Request     |Request|         |           |     |                |
   +=============+=======+=========+===========+=====+================+
   | 0+          |0+     | 0       | 0         |245.3| DHCPv6-Options |
   +-------------+-------+---------+-----------+-----+----------------+
   | 0+          |0+     | 0       | 0         |245.4| DHCPv4-Options |
   +-------------+-------+---------+-----------+-----+----------------+

                       Table 1: Table of Attributes

   Notation for Table 1:

   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

8.1.  New RADIUS Attributes

   IANA has assigned two new RADIUS attribute types in the "Radius
   Attribute Types" [RADIUS-Types] registry:

            +=======+================+===========+===========+
            | Value | Description    | Data Type | Reference |
            +=======+================+===========+===========+
            | 245.3 | DHCPv6-Options | string    | RFC 9445  |
            +-------+----------------+-----------+-----------+
            | 245.4 | DHCPv4-Options | string    | RFC 9445  |
            +-------+----------------+-----------+-----------+

                      Table 2: New RADIUS Attributes


8.2.  New RADIUS Attribute Permitted in DHCPv6 RADIUS Option

   IANA has added the following entry to the "RADIUS Attributes
   Permitted in DHCPv6 RADIUS Option" subregistry in the "Dynamic Host
   Configuration Protocol for IPv6 (DHCPv6)" registry [DHCPv6]:

                +===========+================+===========+
                | Type Code | Attribute      | Reference |
                +===========+================+===========+
                | 245.3     | DHCPv6-Options | RFC 9445  |
                +-----------+----------------+-----------+

                      Table 3: New RADIUS Attribute
                    Permitted in DHCPv6 RADIUS Option


8.3.  RADIUS Attributes Permitted in RADIUS Attributes DHCP Suboption

   IANA has created a new subregistry entitled "RADIUS Attributes
   Permitted in RADIUS Attributes DHCP Suboption" in the "Dynamic Host
   Configuration Protocol (DHCP) and Bootstrap Protocol (BOOTP)
   Parameters" registry [BOOTP].

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

   The initial contents of this subregistry are listed in Table 4.  The
   Reference field includes 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] |
               +-----------+------------------+-----------+
               | 245.4     | DHCPv4-Options   | RFC 9445  |
               +-----------+------------------+-----------+

                   Table 4: Initial Contents of RADIUS
                      Attributes Permitted in RADIUS
                    Attributes DHCP Suboption Registry


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


8.4.1.  DHCPv6

   IANA has created a new subregistry entitled "DHCPv6 Options Permitted
   in the RADIUS DHCPv6-Options Attribute" in the "Dynamic Host
   Configuration Protocol for IPv6 (DHCPv6)" registry [DHCPv6].

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

   The initial content of this subregistry is listed in Table 5.  The
   Value and Description fields echo those in the "Option Codes"
   subregistry of [DHCPv6].  The Reference field includes the document
   that registers or specifies the option.

                   +=======+===============+===========+
                   | Value | Description   | Reference |
                   +=======+===============+===========+
                   | 144   | OPTION_V6_DNR | RFC 9445  |
                   +-------+---------------+-----------+

                        Table 5: Initial Content of
                      DHCPv6 Options Permitted in the
                      RADIUS DHCPv6-Options Attribute
                                  Registry


8.4.2.  DHCPv4

   IANA has created a new subregistry 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 subregistry is Expert Review
   (Section 4.5 of [RFC8126]).  See more details in Section 8.4.3.

   The initial content of this subregistry is listed in Table 6.  The
   Tag and Name fields echo those in the "BOOTP Vendor Extensions and
   DHCP Options" subregistry of [BOOTP].  The Reference field includes
   the document that registers or specifies the option.

                    +=====+===============+===========+
                    | Tag | Name          | Reference |
                    +=====+===============+===========+
                    | 162 | OPTION_V4_DNR | RFC 9445  |
                    +-----+---------------+-----------+

                        Table 6: Initial Content of
                      DHCPv4 Options Permitted in the
                      RADIUS DHCPv4-Options Attribute
                                  Registry


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.

   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.  References

9.1.  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>.

   [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>.

9.2.  Informative References

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

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

   [DNR]      Boucadair, M., Ed., Reddy.K, T., Ed., Wing, D., Cook, N.,
              and T. Jensen, "DHCP and Router Advertisement Options for
              the Discovery of Network-designated Resolvers (DNR)", Work
              in Progress, Internet-Draft, draft-ietf-add-dnr-16, 27
              April 2023, <https://datatracker.ietf.org/doc/html/draft-
              ietf-add-dnr-16>.

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

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, DOI 10.17487/RFC2131, March 1997,
              <https://www.rfc-editor.org/info/rfc2131>.

   [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>.

   [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>.

   [RFC6977]  Boucadair, M. and X. Pougnard, "Triggering DHCPv6
              Reconfiguration from Relay Agents", RFC 6977,
              DOI 10.17487/RFC6977, July 2013,
              <https://www.rfc-editor.org/info/rfc6977>.

   [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>.

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 reviews, Robert Sparks for the
   genart review, and Tatuya Jinmei for the intdir review.

   Thanks to Éric Vyncke, Paul Wouters, and Warren Kumari for the IESG
   review.

Authors' Addresses

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


   Tirumaleswar Reddy.K
   Nokia
   India
   Email: kondtir@gmail.com


   Alan DeKok
   FreeRADIUS
   Email: aland@freeradius.org
