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Versions: (draft-mglt-homenet-front-end-naming-delegation) 00 01 02 03 04 05 06 07 08 09

Homenet                                                       D. Migault
Internet-Draft                                                  Ericsson
Intended status: Informational                                  R. Weber
Expires: May 20, 2020                                            Nominum
                                                           M. Richardson
                                                Sandelman Software Works
                                                               R. Hunter
                                                    Globis Consulting BV
                                                            C. Griffiths

                                                             W. Cloetens
                                                              SoftAtHome
                                                       November 17, 2019


         Outsourcing Home Network Authoritative Naming Service
           draft-ietf-homenet-front-end-naming-delegation-09

Abstract

   The Homenet Naming authority is responsible for making devices within
   the home network accessible by name within the home network as well
   as from outside the home network (e.g. the Internet).  The names of
   the devices accessible from the Internet are stored in the Public
   Homenet Zone, served by a DNS authoritative server.  It is unlikely
   that home networks will contain sufficiently robust platforms
   designed to host a service such as the DNS on the Internet and as
   such would expose the home network to DDoS attacks.

   This document describes a mechanism that enables the Home Network
   Authority (HNA) to outsource the naming service to the Outsourcing
   Infrastructure via a Distribution Master (DM).

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."




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   This Internet-Draft will expire on May 20, 2020.

Copyright Notice

   Copyright (c) 2019 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 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.  Requirements notation . . . . . . . . . . . . . . . . . . . .   3
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Alternative solutions . . . . . . . . . . . . . . . . . .   5
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Architecture Description  . . . . . . . . . . . . . . . . . .   7
     4.1.  Architecture Overview . . . . . . . . . . . . . . . . . .   7
     4.2.  Distribution Master Communication Channels  . . . . . . .  10
   5.  Control Channel between HNA and DM  . . . . . . . . . . . . .  11
     5.1.  Information to build the Public Homenet Zone. . . . . . .  11
     5.2.  Information to build the DNSSEC chain of trust. . . . . .  12
     5.3.  Information to set the Synchronization Channel, . . . . .  12
     5.4.  Deleting the delegation . . . . . . . . . . . . . . . . .  13
     5.5.  Messages Exchange Description . . . . . . . . . . . . . .  13
       5.5.1.  Retrieving information for the Public Homenet Zone. .  13
       5.5.2.  Providing information for the DNSSEC chain of trust .  14
       5.5.3.  Providing information for the Synchronization Channel  14
       5.5.4.  HNA instructing deleting the delegation . . . . . . .  15
     5.6.  Securing the Control Channel between HNA and DM . . . . .  15
     5.7.  Implementation Tips . . . . . . . . . . . . . . . . . . .  16
   6.  DM Synchronization Channel between HNA and DM . . . . . . . .  17
     6.1.  Securing the Synchronization Channel between HNA and DM .  18
   7.  DM Distribution Channel . . . . . . . . . . . . . . . . . . .  18
   8.  HNA Security Policies . . . . . . . . . . . . . . . . . . . .  18
   9.  DNSSEC compliant Homenet Architecture . . . . . . . . . . . .  19
   10. Homenet Reverse Zone  . . . . . . . . . . . . . . . . . . . .  19
   11. Renumbering . . . . . . . . . . . . . . . . . . . . . . . . .  20
     11.1.  Hidden Primary . . . . . . . . . . . . . . . . . . . . .  20
     11.2.  Distribution Master  . . . . . . . . . . . . . . . . . .  21
   12. Operational considerations for Offline/Disconnected



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       resolution  . . . . . . . . . . . . . . . . . . . . . . . . .  22
   13. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  22
   14. Security Considerations . . . . . . . . . . . . . . . . . . .  23
     14.1.  HNA DM channels  . . . . . . . . . . . . . . . . . . . .  23
     14.2.  Names are less secure than IP addresses  . . . . . . . .  23
     14.3.  Names are less volatile than IP addresses  . . . . . . .  23
     14.4.  DNS Reflection Attacks . . . . . . . . . . . . . . . . .  23
     14.5.  Reflection Attack involving the Hidden Primary . . . . .  24
     14.6.  Reflection Attacks involving the DM  . . . . . . . . . .  25
     14.7.  Reflection Attacks involving the Public Authoritative
            Servers  . . . . . . . . . . . . . . . . . . . . . . . .  26
     14.8.  Flooding Attack  . . . . . . . . . . . . . . . . . . . .  26
     14.9.  Replay Attack  . . . . . . . . . . . . . . . . . . . . .  27
   15. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  27
   16. Acknowledgment  . . . . . . . . . . . . . . . . . . . . . . .  28
   17. Annex . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
     17.1.  Envisioned deployment scenarios  . . . . . . . . . . . .  28
       17.1.1.  CPE Vendor . . . . . . . . . . . . . . . . . . . . .  28
       17.1.2.  Agnostic CPE . . . . . . . . . . . . . . . . . . . .  29
     17.2.  Example: Homenet Zone  . . . . . . . . . . . . . . . . .  29
     17.3.  Example: HNA necessary parameters for outsourcing  . . .  31
   18. References  . . . . . . . . . . . . . . . . . . . . . . . . .  32
     18.1.  Normative References . . . . . . . . . . . . . . . . . .  33
     18.2.  Informative References . . . . . . . . . . . . . . . . .  36
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  36

1.  Requirements notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  Introduction

   IPv6 provides global end to end IP connectivity.  End users prefer to
   use names instead of long and complex IPv6 addresses when accessing
   services hosted in the home network.

   [RFC7368] recommends that home networks be resilient to connectivity
   disruption from the ISP.  The public names should be resolvable
   within the home network and on the Internet, even when there are
   disruptions.  This could be achieved by a device inside the home
   network that builds, publishes, and manages a Public Homenet Zone,
   thus providing bindings between public names, IP addresses, and other
   RR types.

   The management of the names can be a role that the Customer Premises
   Equipment (CPE) does.  Other devices in the home network could



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   fulfill this role e.g. a NAS server, but for simplicity, this
   document assumes the function is located on one of the CPE devices.

   A home network may have multiple CPEs.  Since management of the
   Public Homenet Zone involves DNS specific mechanisms that cannot be
   distributed over multiple servers (primary server), when multiple
   nodes can potentially manage the Public Homenet Zone, a single node
   needs to be selected per outsourced zone.  This selected node is
   designated as providing the Homenet Naming Authority (HNA) function.

   The process by which a single HNA is selected per zone is not in
   scope for this document.

   CPEs, which may host the HNA function, as well as home network
   devices, are usually low powered devices not designed for terminating
   heavy traffic.  As a result, hosting an authoritative DNS service
   visible to the Internet may expose the home network to resource
   exhaustion and other attacks.  Additionally, the names could become
   unavailable during disruptions of the upstream Internet connectivity.

   In order to avoid resource exhaustion and other attacks, this
   document describes an architecture that outsources the authoritative
   naming service of the home network.  More specifically, the HNA
   builds the Public Homenet Zone and outsources it to an Outsourcing
   Infrastructure via a Distribution Master (DM).  The Outsourcing
   Infrastructure is in charge of publishing the corresponding Public
   Homenet Zone on the Internet.  The transfer of DNS zone information
   is achieved using standard DNS mechanisms involving primary and
   secondary DNS servers, with the HNA hosted primary being a stealth
   primary, and the Distribution Master a secondary.

   Section 4.1 provides an architecture description that describes the
   relation between the HNA and the Outsourcing Architecture.  In order
   to keep the Public Homenet Zone up-to-date Section 6 describes how
   the HNA and the Outsourcing Infrastructure synchronizes the Pubic
   Homenet Zone.

   The proposed architecture is explicitly designed to enable fully
   functional DNSSEC, and the Public Homenet Zone is expected to be
   signed with a secure delegation.  DNSSEC key management and zone
   signing is handled by the HNA.

   Section 10 discusses management of one or more reverse zones.
   Section 11 discusses how renumbering should be handled.  Finally,
   Section 13 and Section 14 respectively discuss privacy and security
   considerations when outsourcing the Public Homenet Zone.





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   The Public Homenet Zone is expected to contain public information
   only in a single universal view.  This document does not define how
   the information required to construct this view is derived.

   It is also not in the scope of this document to define names for
   exclusive use within the boundaries of the local home network.
   Instead, local scope information is expected to be provided to the
   home network using local scope naming services. mDNS [RFC6762] DNS-SD
   [RFC6763] are two examples of these services.  Currently mDNS is
   limited to a single link network.  However, future protocols and
   architectures [I-D.ietf-homenet-simple-naming] are expected to
   leverage this constraint as pointed out in [RFC7558].

2.1.  Alternative solutions

   An alternative existing solution in IPv4 is to have a single zone,
   where a host uses a RESTful HTTP service to register a single name
   into a common public zone.  This is often called "Dynamic DNS", and
   there are a number of commercial providers, including Dyn, Gandi etc.
   These solutions were typically used by a host behind the CPE to make
   it's CPE IPv4 address visible, usually in order to enable incoming
   connections.

   For a small number (one to three) of hosts, use of such a system
   provides an alternative to the architecture described in this
   document.

   The alternative does suffer from some severe limitations:

   o  the CPE/HNA router is unaware of the process, and cannot respond
      to queries for these names when there are disruptions in
      connectivity.  This makes the home user or application dependent
      on having to resolve different names in the event of outages or
      disruptions.

   o  the CPE/HNA router cannot control the process.  Any host can do
      this regardless of whether or not the home network administrator
      wants the name published or not.  There is therefore no possible
      audit trail.

   o  the credentials for the dynamic DNS server need to be securely
      transferred to all hosts that wish to use it.  This is not a
      problem for a technical user to do with one or two hosts, but it
      does not scale to multiple hosts and becomes a problem for non-
      technical users.

   o  "all the good names are taken" - current services put everyone's
      names into some small set of zones, and there are often conflicts.



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      Distinguishing similar names by delegation of zones was among the
      primary design goals of the DNS system.

   o  The RESTful services do not always support all RR types.  The
      homenet user is dependent on the service provider supporting new
      types.  By providing full DNS delegation, this document enables
      all RR types and also future extensions.

   There is no technical reason why a RESTful cloud service could not
   provide solutions to many of these problems, but this document
   describes a DNS based solution.

3.  Terminology

   o  Customer Premises Equipment: (CPE) is a router providing
      connectivity to the home network.

   o  Homenet Zone: is the DNS zone for use within the boundaries of the
      home network: home.arpa, see [RFC8375]).  This zone is not
      considered public and is out of scope for this document.

   o  Registered Homenet Domain: is the Domain Name associated with the
      home network.

   o  Public Homenet Zone: contains the names in the home network that
      are expected to be publicly resolvable on the Internet.

   o  Homenet Naming Authority: (HNA) is a function responsible for
      managing the Public Homenet Zone.  This includes populating the
      Public Homenet Zone, signing the zone for DNSSEC, as well as
      managing the distribution of that Homenet Zone to the Outsourcing
      Infrastructure.

   o  Outsourcing Infrastructure: is the infrastructure responsible for
      receiving the Public Homenet Zone and publishing it on the
      Internet.  It is mainly composed of a Distribution Master and
      Public Authoritative Servers.

   o  Public Authoritative Servers: are the authoritative name servers
      for the Public Homenet Zone.  Name resolution requests for the
      Homenet Domain are sent to these servers.  For resiliency the
      Public Homenet Zone SHOULD be hosted on multiple servers.

   o  Homenet Authoritative Servers: are authoritative name servers
      within the Homenet network.

   o  Distribution Master (DM): is the (set of) server(s) to which the
      HNA synchronizes the Public Homenet Zone, and which then



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      distributes the relevant information to the Public Authoritative
      Servers.

   o  Homenet Reverse Zone: The reverse zone file associated with the
      Public Homenet Zone.

   o  Reverse Public Authoritative Servers: equivalent to Public
      Authoritative Servers specifically for reverse resolution.

   o  Reverse Distribution Master: equivalent to Distribution Master
      specifically for reverse resolution.

   o  Homenet DNSSEC Resolver: a resolver that performs a DNSSEC
      resolution on the home network for the Public Homenet Zone.  The
      resolution is performed requesting the Homenet Authoritative
      Servers.

   o  DNSSEC Resolver: a resolver that performs a DNSSEC resolution on
      the Internet for the Public Homenet Zone.  The resolution is
      performed requesting the Public Authoritative Servers.

4.  Architecture Description

   This section provides an overview of the architecture for outsourcing
   the authoritative naming service from the HNA to the Outsourcing
   Infrastructure in Section 4.1.  Section Section 17.2 and Section 17.3
   illustrates this architecture with the example of a Public Homenet
   Zone as well as necessary parameter to configure the HNA.

4.1.  Architecture Overview

   Figure Figure 1 illustrates the architecture where the HNA outsources
   the publication of the Public Homenet Zone to the Outsourcing
   Infrastructure.

   The Public Homenet Zone is identified by the Registered Homenet
   Domain Name - example.com.

   ".local" as well as ".home.arpa" are explicitly not considered as
   Public Homenet zones.

   The HNA SHOULD build the Public Homenet Zone in a single view
   populated with all resource records that are expected to be published
   on the Internet.

   Resource records associated with services or devices that are not
   expected to be resolvable from outside the home network, or resource




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   records bound to non-globally reachable IP addresses e.g.  ULA, MUST
   NOT be part of the Public Homenet Zone.

   How the Public Homenet Zone is populated is out of the scope of this
   document.  The node providing the HNA function may also host or
   interact with multiple services to determine name-to-address
   mappings, such as a web GUI, DHCP [RFC6644] or mDNS [RFC6762].  These
   services may coexist and may be used to populate the Public Homenet
   Zone.

   The HNA also signs the Public Homenet Zone.  The HNA handles all
   operations and keying material required for DNSSEC, so there is no
   provision made in this architecture for transferring private DNSSEC
   related keying material between the HNA and the DM.

   Once the Public Homenet Zone has been built, the HNA outsources it to
   the Outsourcing Infrastructure as described in Figure 1.

   The HNA acts as a hidden primary while the DM behaves as a secondary
   responsible to distribute the Public Homenet Zone to the multiple
   Public Authoritative Servers that Outsourcing Infrastructure is
   responsible for.

   The DM has 3 communication channels: * a DM Control Channel (see
   section Section 5) to configure the HNA and the Outsourcing
   Infrastructure, * a DM Synchronization Channel (see section Section 6
   to synchronize the Public Homenet Zone on the HNA and on the DM.  *
   one or more Distribution Channels (see section Section 7 that
   distributes the Public Homenet Zone from the DM to the Public
   Authoritative Server serving the Public Homenet Zone on the Internet.

   There MAY be multiple DM's, and multiple servers per DM.  This text
   assumes a single DM server for simplicity, but there is no reason why
   each channel need to be implemented on the same server, or indeed use
   the same code base.

   It is important to note that while the HNA is configured as an
   authoritative server, it is not expected to answer to DNS requests
   from the public Internet for the Public Homenet Zone.  The function
   of the HNA is limited to building the zone and synchronization with
   the DM.

   The addresses associated with the HNA SHOULD NOT be mentioned in the
   NS records of the Public Homenet zone, unless additional security
   provisions necessary to protect the HNA from external attack have
   been taken.





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   The Outsourcing Infrastructure is also responsible for ensuring the
   DS record has been updated in the parent zone.

   Resolution is performed by the DNSSEC resolvers.  When the resolution
   is performed outside the home network, the DNSSEC Resolver resolves
   the DS record on the Global DNS and the name associated to the Public
   Homenet Zone (example.com) on the Public Authoritative Servers.

   When the resolution is performed from within the home network, the
   Homenet DNSSEC Resolver may proceed similarly.  On the other hand, to
   provide resilience to the Public Homenet Zone in case of disruption,
   the Homenet DNSSEC Resolver SHOULD be able to perform the resolution
   on the authoritative name service of the home network implemented by
   the Homenet Authoritative Servers.  These servers are not expected to
   be mentioned in the Public Homenet Zone, nor to be accessible from
   the Internet.  As such their information as well as the corresponding
   signed DS record MAY be provided by the HNA to the Homenet DNSSEC
   Resolvers e.g. using HNCP.  Such configuration is outside the scope
   of this document.

   How the Homenet Authoritative Servers are provisioned is also out of
   scope of this specification.  It could be implemented using primary
   secondaries servers, or via rsync.  In some cases, the HNA and
   Homenet Authoritative Servers may be combined together which would
   result in a common instantiation of an authoritative server on the
   WAN and inner interface.  Other mechanisms may also be used.

























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           Home network                 |         Internet
                                        |
                                        | +----------------------------+
                                        | | Outsourcing Infrastructure |
                             Control    | |                            |
    +-----------------------+Channel    | |  +-----------------------+ |
    |         HNA           |<-------------->| Distribution Master   | |
    |+---------------------+|           | |  |+---------------------+| |
    || Public Homenet Zone ||Synchronization || Public Homenet Zone || |
    || (example.com)       ||Channel    | |  ||  (example.com)      || |
    |+---------------------+|<-------------->|+---------------------+| |
    +----------------------+|           | |  +-----------------------+ |
                                        | |           ^ Distribution   |
                                        | |           | Channel        |
    +-----------------------+           | |           v                |
    | Homenet Authoritative |           | |  +-----------------------+ |
    | Server(s)             |           | |  | Public Authoritative  | |
    |+---------------------+|           | |  | Server(s)             | |
    ||Public Homenet Zone  ||           | |  |+---------------------+| |
    || (example.com)       ||           | |  || Public Homenet Zone || |
    |+---------------------+|           | |  ||  (example.com)      || |
    +-----------------------+           | |  |+---------------------+| |
               ^   |                    | |  +-----------------------+ |
               |   |                    | +----------^---|-------------+
               |   |                    |            |   |
               |   |           name resolution       |   |
               |   v                    |            |   v
     +----------------------+           | +-----------------------+
     |       Homenet        |           | |       Internet        |
     |    DNSSEC Resolver   |           | |    DNSSEC Resolver    |
     +----------------------+           | +-----------------------+

           Figure 1: Homenet Naming Architecture Name Resolution

4.2.  Distribution Master Communication Channels

   This section details the interfaces and channels of the DM, that is
   the Control Channel, the Synchronization Channel and the Distribution
   Channel.

   The Control Channel and the Synchronization Channel are the
   interfaces used between the HNA and the Outsourcing Infrastructure.
   The entity within the Outsourcing Infrastructure responsible to
   handle these communications is the DM and communications between the
   HNA and the DM SHOULD be protected and mutually authenticated.  While
   section Section 5.6 discusses in more depth the different security
   protocols that could be used to secure, this specification RECOMMENDS




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   the use of TLS with mutually authentication based on certificates to
   secure the channel between the HNA and the DM.

   The Control Channel is used to set up the Synchronization Channel.
   We assume that the HNA initiates the Control Channel connection with
   the DM and as such has a prior knowledge of the DM identity (X509
   certificate), the IP address and port to use and protocol to set
   secure session.  We also assume the DM has knowledge of the identity
   of the HNA (X509 certificate) as well as the Registered Homenet
   Domain.

   The information exchanged between the HNA and the DM is using DNS
   messages.  DNS messages can be protected using various kind of
   transport layers, among others, UDP:53/DTLS, TLS/TCP:53, HTTPS:443.
   There was consideration to using a standard TSIG [RFC2845] or SIG(0)
   [RFC2931] to perform a dynamic DNS update to the DM.  There are a
   number of issues with this.  The main one is that the Dynamic DNS
   update would also update the zone's NS records, while the goal is to
   update the Distribution Master's configuration files.  The visible NS
   records SHOULD remain pointing at the cloud provider's anycast
   addresses.  Revealing the address of the HNA in the DNS is not
   desireable.

   This specification also assumes the same transport protocol and ports
   used by the DM to serve the Control Channel and by the HNA to serve
   the Synchronization Channel are the same.

   The Distribution Channel is internal to the Outsourcing
   Infrastructure and as such is not the primary concern of this
   specification.

5.  Control Channel between HNA and DM

   The DM Control Channel is used by the HNA and the Outsourcing
   Infrastructure to exchange information related to the configuration
   of the delegation which includes:

5.1.  Information to build the Public Homenet Zone.

   More specifically, the Public Homenet Zone contains information that
   is related to the infrastructure serving the zone.  In our case, the
   infrastructure serving the Public Homenet Zone is the Outsourcing
   Infrastructure, so this information MUST reflect that Outsourcing
   Infrastructure and MUST be provided to the HNA.

   The information includes at least names and IP addresses of the
   Public Authoritative Servers.  In term of RRset information this
   corresponds, for the Registered Homenet Domain the MNAME of the SOA,



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   the NS and associated A and AAA RRsets.  Optionally the Outsourcing
   Infrastructure MAY also provide operational parameters such as other
   fields of SOA (SERIAL, RNAME, REFRESH, RETRY, EXPIRE and MINIMUM).
   As the information is necessary for the HNA to proceed and the
   information is associated to the Outsourcing Infrastructure, this
   information exchange is mandatory.

5.2.  Information to build the DNSSEC chain of trust.

   The HNA SHOULD provide the hash of the KSK (DS RRset), so the that
   Outsourcing Infrastructure provides this value to the parent zone.  A
   common deployment use case is that the Outsourcing Infrastructure is
   the registrar of the Registered Homenet Domain, and as such, its
   relationship with the registry of the parent zone enables it to
   update the parent zone.  When such relation exists, the HNA should be
   able to request the Outsourcing Infrastructure to update the DS RRset
   in the parent zone.  A direct update is especially necessary to
   initialize the chain of trust.

   Though the HNA may also later directly update the values of the DS
   via the Control Channel, it is RECOMMENDED to use other mechanisms
   such as CDS and CDNSKEY [RFC7344] are used for key roll overs.

   As some deployment may not provide an Outsourcing Infrastructure that
   will be able to update the DS in the parent zone, this information
   exchange is OPTIONAL.

   By accepting the DS, the DM commits in taking care of advertising the
   DS to the parent zone.  Upon refusal, the DM MUST clearly indicate
   the DM does not have the capacity to proceed to the update.

5.3.  Information to set the Synchronization Channel,

   That information sets the primary/secondary relation between the HNA
   and the DM.  The HNA works as a primary authoritative DNS server, and
   MUST provide the corresponding IP address.

   The specified IP address on the HNA side and the currently used IP
   address of the DM defines the IP addresses involved in the
   Synchronization Channel.  Ports and transport protocol are the same
   as those used by the Control Channel.  By default, the same IP
   address used by the HNA is considered by the DM.  Exchange of this
   information is OPTIONAL.








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5.4.  Deleting the delegation

   The purpose of the previous sections were to exchange information in
   order to set a delegation.  The HNA MUST also be able to delete a
   delegation with a specific DM.  Upon an instruction of deleting the
   delegation, the DM MUST stop serving the Public Homenet Zone.

5.5.  Messages Exchange Description

   There are multiple ways these information could be exchanged between
   the HNA and the DM.  This specification defines a mechanism that re-
   use the DNS exchanges format.  The intention is to reuse standard
   libraries especially to check the format of the exchanged fields as
   well as to minimize the additional libraries needed for the HNA.  The
   re-use of DNS exchanges achieves these goals.  Note that while
   information is provided using DNS exchanges, the exchanged
   information is not expected to be set in any zone file, instead this
   information is expected to be processed appropriately.

   The Control Channel is not expected to be a long term session.  After
   a predefined timer the Control Channel is expected to be terminated.
   The Control Channel MAY Be re-opened at any time later.

   The provisioning process SHOULD provide a method of securing the
   control channel, so that the content of messages can be
   authenticated.  This authentication MAY be based on certificates for
   both the DM and each HNA.  The DM may also create the initial
   configuration for the delegation zone in the parent zone during the
   provisioning process.

5.5.1.  Retrieving information for the Public Homenet Zone.

   The information provided by the DM to the HNA is retrieved by the HNA
   with a AXFR exchange.  The AXFR message enables the response to
   contain any type of RRsets.  The response might be extended in the
   future if additional information will be needed.  Alternatively, the
   information provided by the HNA to the DM is pushed by the HNA via a
   DNS update exchange.

   To retrieve the necessary information to build the Public Homenet
   Zone, the HNA MUST send an DNS request of type AXFR associated to the
   Registered Homenet Domain.  The DM MUST respond with a zone template.
   The zone template MUST contain a RRset of type SOA, one or multiple
   RRset of type NS and at least one RRset of type A or AAAA.  The SOA
   RR is used to indicate to the HNA the value of the MNAME of the
   Public Homenet Zone.  The NAME of the SOA RR MUST be the Registered
   Homenet Domain.  The MNAME value of the SOA RDATA is the value
   provided by the Outsourcing Infrastructure to the HNA.  Other RDATA



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   values (RNAME, REFRESH, RETRY, EXPIRE and MINIMUM) are provided by
   the Outsourcing Infrastructure as suggestions.  The NS RRsets are
   used to carry the Public Authoritative Servers of the Outsourcing
   Infrastructure.  Their associated NAME MUST be the Registered Homenet
   Domain.  The TTL and RDATA are those expected to be published on the
   Public Homenet Zone.  The RRsets of Type A and AAAA MUST have their
   NAME matching the NSDNAME of one of the NS RRsets.

   Upon receiving the response, the HNA MUST validate the conditions on
   the SOA, NS and A or AAAA RRsets.  If an error occurs, the HNA MUST
   stop proceeding and MUST report an error.  Otherwise, the HNA builds
   the Public Homenet Zone by setting the MNAME value of the SOA as
   indicated by the SOA provided by the AXFR response.  The HNA SHOULD
   set the value of NAME, REFRESH, RETRY, EXPIRE and MINIMUM of the SOA
   to those provided by the AXFR response.  The HNA MUST insert the NS
   and corresponding A or AAAA RRset in its Public Homenet Zone.  The
   HNA MUST ignore other RRsets.  If an error message is returned by the
   DM, the HNA MUST proceed as a regular DNS resolution.  Error messages
   SHOULD be logged for further analysis.  If the resolution does not
   succeed, the outsourcing operation is aborted and the HNA MUST close
   the Control Channel.

5.5.2.  Providing information for the DNSSEC chain of trust

   To provide the DS RRset to initialize the DNSSEC chain of trust the
   HNA MAY send a DNS UPDATE [RFC2136] message.  The NAME in the SOA
   MUST be set to the parent zone of the Registered Homenet Domain -
   that is where the DS records should be inserted.  The DS RRset MUST
   be placed in the Update section of the UPDATE query, and the NAME
   SHOULD be set to the Registered Homenet Domain.  The rdata of the DS
   RR SHOULD correspond to the DS record to be inserted in the parent
   zone.

   A NOERROR response from the MD is a commitment to update the parent
   zone with the provided DS.  An error indicates the MD will not update
   the DS, and other method should be used by the HNA.

5.5.3.  Providing information for the Synchronization Channel

   To provide the IP address of the primary, the HNA MAY send a DNS
   UPDATE message.  The NAME in the SOA MUST be the parent zone of the
   Registered Homenet Domain.  The Update section MUST be a RRset of
   Type NS.  The NAME associated to the NS RRSet MUST be the Registered
   Domain Name.  The RDATA MUST be a FQDN that designates the IP
   addresses associated to the primary.  There may be multiple IP
   addresses.  These IP addresses MUST be provided in the additional
   section.  The reason to provide these IP addresses is that it is NOT
   RECOMMENDED to publish these IP addresses.  As a result, it is not



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   expected to resolve them.  IP addresses are provided via RRsets of
   type A or AAAA.  The NAME associated to RRsets of type A and AAAA
   MUST be the Registered Homenet Domain.

   A NOERROR response indicates the DM has configured the secondary and
   is committed to serve as a secondary.  An error indicates the DM is
   not configured as a secondary.

   The regular DNS error message SHOULD be returned to the HNA when an
   error occurs.  In particular a FORMERR is returned when a format
   error is found, this error includes when unexpected RRSets are added
   or when RRsets are missing.  A SERVFAIL error is returned when a
   internal error is encountered. a NOTZONE error is returned when
   update and Zone sections are not coherent, a NOTAUTH error is
   returned when the DM is not authoritative for the Zone section.  A
   REFUSED error is returned when the DM refuses to proceed to the
   configuration and the requested action.

5.5.4.  HNA instructing deleting the delegation

   To instruct to delete the delegation the HNA MAY send a DNS UPDATE
   Delete message.  The NAME in the SOA MUST be the parent zone of the
   Registered Homenet Domain.  The Update section MUST be a RRset of
   Type NS.  The NAME associated to the NS RRSet MUST be the Registered
   Domain Name.  As indictaed by [RFC2136] section 2.5.2 the delete
   instruction is set by setting the TTL to 0, the CLass to ANY, the
   RDLENGTH to 0 and the RDATA MUST be empty.

5.6.  Securing the Control Channel between HNA and DM

   The control channel between the HNA and the DM MUST be secured at
   both the HNA and the DM.

   Secure protocols (like TLS [RFC5246] / DTLS [RFC6347]) SHOULD be used
   to secure the transactions between the DM and the HNA.

   The advantage of TLS/DTLS is that this technology is widely deployed,
   and most of the devices already embed TLS/DTLS libraries, possibly
   also taking advantage of hardware acceleration.  Further, TLS/DTLS
   provides authentication facilities and can use certificates to
   authenticate the DM and the HNA.  On the other hand, using TLS/DTLS
   requires implementing DNS exchanges over TLS/DTLS, as well as a new
   service port.  This document RECOMMENDS this option.

   The HNA SHOULD authenticate inbound connections from the DM using
   standard mechanisms, such as a public certificate with baked-in root
   certificates on the HNA, or via DANE {!RFC6698}}.




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   The DM SHOULD authenticate the HNA and check that inbound messages
   are from the appropriate client.  The DM MAY use a self-signed CA
   certificate mechanism per HNA, or public certificates for this
   purpose.

   IPsec [RFC4301] IKEv2 [RFC7296] MAY also be used to secure
   transactions between the HNA and the DM.  Similarly to TLS/DTLS, most
   HNAs already embed an IPsec stack, and IKEv2 supports multiple
   authentication mechanisms via the EAP framework.  In addition, IPsec
   can be used to protect DNS exchanges between the HNA and the DM
   without any modifications of the DNS server or client.  DNS
   integration over IPsec only requires an additional security policy in
   the Security Policy Database (SPD).  One disadvantage of IPsec is
   that NATs and firewall traversal may be problematic.  However, in our
   case, the HNA is connected to the Internet, and IPsec communication
   between the HNA and the DM should not be impacted by middle boxes.

   How the PSK can be used by any of the TSIG, TLS/DTLS or IPsec
   protocols: Authentication based on certificates implies a mutual
   authentication and thus requires the HNA to manage a private key, a
   public key, or certificates, as well as Certificate Authorities.
   This adds complexity to the configuration especially on the HNA side.
   For this reason, we RECOMMEND that the HNA MAY use PSK or certificate
   based authentication, and that the DM MUST support PSK and
   certificate based authentication.

   Note also that authentication of message exchanges between the HNA
   and the DM SHOULD NOT use the external IP address of the HNA to index
   the appropriate keys.  As detailed in Section 11, the IP addresses of
   the DM and the Hidden Primary are subject to change, for example
   while the network is being renumbered.  This means that the necessary
   keys to authenticate transaction SHOULD NOT be indexed using the IP
   address, and SHOULD be resilient to IP address changes.

5.7.  Implementation Tips

   The Hidden Primary Server on the HNA differs from a regular
   authoritative server for the home network due to:

   o  Interface Binding: the Hidden Primary Server will almost certainly
      listen on the WAN Interface, whereas a regular authoritative
      server for the home network would listen on the internal home
      network interface.

   o  Limited exchanges: the purpose of the Hidden Primary Server is to
      synchronize with the DM, not to serve any zones to end users, or
      the public Internet.




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   As a result, exchanges are performed with specific nodes (the DM).
   Further, exchange types are limited.  The only legitimate exchanges
   are: NOTIFY initiated by the Hidden Primary and IXFR or AXFR
   exchanges initiated by the DM.  On the other hand, regular
   authoritative servers would respond to any hosts, and any DNS query
   would be processed.  The HNA SHOULD filter IXFR/AXFR traffic and drop
   traffic not initiated by the DM.  The HNA MUST listen for DNS on TCP
   and UDP and MUST at least allow SOA lookups of the Homenet Zone.

6.  DM Synchronization Channel between HNA and DM

   The DM Synchronization Channel is used for communication between the
   HNA and the DM for synchronizing the Public Homenet Zone.  Note that
   the Control Channel and the Synchronization Channel are by
   construction different channels even though there they MAY use the
   same IP addresses.  In fact the Control Channel is set between the
   HNA working as a client using port YYYY (a high range port) toward a
   service provided by the MD at port XX (well known port).  On the
   other hand, the Synchronization Channel is set between the MD working
   as a client using port ZZZZ ( a high range port) toward a service a
   service provided by the HNA at port XX.  As a result, even though the
   same couple of IP addresses may be involved the Control Channel and
   the Synchronization Channel are always disc tint channels.

   Uploading and dynamically updating the zone file on the DM can be
   seen as zone provisioning between the HNA (Hidden Primary) and the DM
   (Secondary Server).  This can be handled via AXFR + DNS UPDATE.

   This document RECOMMENDS use of a primary / secondary mechanism
   instead of the use of DNS UPDATE.  The primary / secondary mechanism
   is RECOMMENDED as it scales better and avoids DoS attacks.  Note that
   even when UPDATE messages are used, these messages are using a
   distinct channel as those used to set the configuration.

   Note that there is no standard way to distribute a DNS primary
   between multiple devices.  As a result, if multiple devices are
   candidate for hosting the Hidden Primary, some specific mechanisms
   should be designed so the home network only selects a single HNA for
   the Hidden Primary.  Selection mechanisms based on HNCP [RFC7788] are
   good candidates.

   The HNA acts as a Hidden Primary Server, which is a regular
   authoritative DNS Server listening on the WAN interface.

   The DM is configured as a secondary for the Homenet Domain Name.
   This secondary configuration has been previously agreed between the
   end user and the provider of the Outsourcing Infrastructure as part




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   of either the provisioning or due to receipt of UPDATE messages on
   the DM Control Channel.

   The Homenet Reverse Zone MAY also be updated either with DNS UPDATE
   [RFC2136] or using a primary / secondary synchronization.

6.1.  Securing the Synchronization Channel between HNA and DM

   The Synchronization Channel used standard DNS request.

   First the primary notifies the secondary that the zone must be
   updated and eaves the secondary to proceed with the update when
   possible/ convenient.

   Then, a NOTIFY message is sent by the primary, which is a small
   packet that is less likely to load the secondary.

   Finally, the AXFR [RFC1034] or IXFR [RFC1995] query performed by the
   secondary is a small packet sent over TCP (section 4.2 [RFC5936]),
   which mitigates reflection attacks using a forged NOTIFY.

   The AXFR request from the DM to the HNA SHOULD be secured.  DNS over
   TLS [RFC7858] is RECOMMENDED.

   When using TLS, the HNA MAY authenticate inbound connections from the
   DM using standard mechanisms, such as a public certificate with
   baked-in root certificates on the HNA, or via DANE {!RFC6698}}

   The HNA MAY apply a simple IP filter on inbound AXFR requests to
   ensure they only arrive from the DM Synchronization Channel.  In this
   case, the HNA SHOULD regularly check (via DNS resolution) that the
   address of the DM in the filter is still valid.

7.  DM Distribution Channel

   The DM Distribution Channel is used for communication between the DM
   and the Public Authoritative Servers.  The architecture and
   communication used for the DM Distribution Channels is outside the
   scope of this document, and there are many existing solutions
   available e.g. rsynch, DNS AXFR, REST, DB copy.

8.  HNA Security Policies

   This section details security policies related to the Hidden Primary
   / Secondary synchronization.

   The Hidden Primary, as described in this document SHOULD drop any
   queries from the home network.  This could be implemented via port



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   binding and/or firewall rules.  The precise mechanism deployed is out
   of scope of this document.  The Hidden Primary SHOULD drop any DNS
   queries arriving on the WAN interface that are not issued from the
   DM.  The Hidden Primary SHOULD drop any outgoing packets other than
   DNS NOTIFY query, SOA response, IXFR response or AXFR responses.  The
   Hidden Primary SHOULD drop any incoming packets other than DNS NOTIFY
   response, SOA query, IXFR query or AXFR query.  The Hidden Primary
   SHOULD drop any non protected IXFR or AXFR exchange,depending on how
   the synchronization is secured.

9.  DNSSEC compliant Homenet Architecture

   [RFC7368] in Section 3.7.3 recommends DNSSEC to be deployed on both
   the authoritative server and the resolver.  The resolver side is out
   of scope of this document, and only the authoritative part of the
   server is considered.

   This document assumes the HNA signs the Public Homenet Zone.

   Secure delegation is achieved only if the DS RRset is properly set in
   the parent zone.  Secure delegation is performed by the HNA or the
   Outsourcing Infrastructures.

   The DS RRset can be updated manually with nsupdate for example.  This
   requires the HNA or the Outsourcing Infrastructure to be
   authenticated by the DNS server hosting the parent of the Public
   Homenet Zone.  Such a trust channel between the HNA and the parent
   DNS server may be hard to maintain with HNAs, and thus may be easier
   to establish with the Outsourcing Infrastructure.  In fact, the
   Public Authoritative Server(s) may use Automating DNSSEC Delegation
   Trust Maintenance [RFC7344].

10.  Homenet Reverse Zone

   This section is focused on the Homenet Reverse Zone.

   Firstly, all considerations for the Public Homenet Zone apply to the
   Homenet Reverse Zone.  The main difference between the Homenet
   Reverse Zone and the Homenet Zone is that the parent zone of the
   Homenet Reverse Zone is most likely managed by the ISP.  As the ISP
   also provides the IP prefix to the HNA, it may be able to
   authenticate the HNA using mechanisms outside the scope of this
   document e.g. the physical attachment point to the ISP network.  If
   the Reverse DM is managed by the ISP, credentials to authenticate the
   HNA for the zone synchronization may be set automatically and
   transparently to the end user.
   [I-D.ietf-homenet-naming-architecture-dhc-options] describes how
   automatic configuration may be performed.



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   With IPv6, the domain space for IP addresses is so large that reverse
   zone may be confronted with scalability issues.  How the reverse zone
   is generated is out of scope of this document.
   [I-D.howard-dnsop-ip6rdns] provides guidance on how to address
   scalability issues.

11.  Renumbering

   This section details how renumbering is handled by the Hidden Primary
   server or the DM.  Both types of renumbering are discussed i.e.
   "make-before-break" and "break-before-make".

   In the make-before-break renumbering scenario, the new prefix is
   advertised, the network is configured to prepare the transition to
   the new prefix.  During a period of time, the two prefixes old and
   new coexist, before the old prefix is completely removed.  In the
   break-before-make renumbering scenario, the new prefix is advertised
   making the old prefix obsolete.

   Renumbering has been extensively described in [RFC4192] and analyzed
   in [RFC7010] and the reader is expected to be familiar with them
   before reading this section.

11.1.  Hidden Primary

   In a renumbering scenario, the Hidden Primary is informed it is being
   renumbered.  In most cases, this occurs because the whole home
   network is being renumbered.  As a result, the Public Homenet Zone
   will also be updated.  Although the new and old IP addresses may be
   stored in the Public Homenet Zone, we recommend that only the newly
   reachable IP addresses be published.

   To avoid reachability disruption, IP connectivity information
   provided by the DNS SHOULD be coherent with the IP plane.  In our
   case, this means the old IP address SHOULD NOT be provided via the
   DNS when it is not reachable anymore.  Let for example TTL be the TTL
   associated with a RRset of the Public Homenet Zone, it may be cached
   for TTL seconds.  Let T_NEW be the time the new IP address replaces
   the old IP address in the Homenet Zone, and T_OLD_UNREACHABLE the
   time the old IP is not reachable anymore.

   In the case of the make-before-break, seamless reachability is
   provided as long as T_OLD_UNREACHABLE - T_NEW > 2 * TTL.  If this is
   not satisfied, then devices associated with the old IP address in the
   home network may become unreachable for 2 * TTL - (T_OLD_UNREACHABLE
   - T_NEW).  In the case of a break-before-make, T_OLD_UNREACHABLE =
   T_NEW, and the device may become unreachable up to 2 * TTL.




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   Once the Public Homenet Zone file has been updated on the Hidden
   Primary, the Hidden Primary needs to inform the Outsourcing
   Infrastructure that the Public Homenet Zone has been updated and that
   the IP address to use to retrieve the updated zone has also been
   updated.  Both notifications are performed using regular DNS
   exchanges.  Mechanisms to update an IP address provided by lower
   layers with protocols like SCTP [RFC4960], MOBIKE [RFC4555] are not
   considered in this document.

   The Hidden Primary SHOULD inform the DM that the Public Homenet Zone
   has been updated by sending a NOTIFY payload with the new IP address.
   In addition, this NOTIFY payload SHOULD be authenticated using SIG(0)
   or TSIG.  When the DM receives the NOTIFY payload, it MUST
   authenticate it.  Note that the cryptographic key used for the
   authentication SHOULD be indexed by the Registered Homenet Domain
   contained in the NOTIFY payload as well as the RRSIG.  In other
   words, the IP address SHOULD NOT be used as an index.  If
   authentication succeeds, the DM MUST also notice the IP address has
   been modified and perform a reachability check before updating its
   primary configuration.  The routability check MAY performed by
   sending a SOA request to the Hidden Primary using the source IP
   address of the NOTIFY.  This exchange is also secured, and if an
   authenticated response is received from the Hidden Primary with the
   new IP address, the DM SHOULD update its configuration file and
   retrieve the Public Homenet Zone using an AXFR or a IXFR exchange.

   Note that the primary reason for providing the IP address is that the
   Hidden Primary is not publicly announced in the DNS.  If the Hidden
   Primary were publicly announced in the DNS, then the IP address
   update could have been performed using the DNS as described in
   Section 11.2.

11.2.  Distribution Master

   Renumbering of the Distribution Master results in it changing its IP
   address.  As the DM is a secondary, the destination of DNS NOTIFY
   payloads MUST be changed, and any configuration/firewalling that
   restricts DNS AXFR/IXFR operations MUST be updated.

   If the DM is configured in the Hidden Primary configuration file
   using a FQDN, then the update of the IP address is performed by DNS.
   More specifically, before sending the NOTIFY, the Hidden Primary
   performs a DNS resolution to retrieve the IP address of the
   secondary.

   As described in Section 11.1, the DM DNS information SHOULD be
   coherent with the IP plane.  The TTL of the Distribution Master name
   SHOULD be adjusted appropriately prior to changing the IP address.



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   Some DNS infrastructure uses the IP address to designate the
   secondary, in which case, other mechanisms must be found.  The reason
   for using IP addresses instead of names is generally to reach an
   internal interface that is not designated by a FQDN, and to avoid
   potential bootstrap problems.  Such scenarios are considered as out
   of scope in the case of home networks.

12.  Operational considerations for Offline/Disconnected resolution

   This section is non-normative.  It provides suggestions on
   operational consideration.  TBD.

13.  Privacy Considerations

   Outsourcing the DNS Authoritative service from the HNA to a third
   party raises a few privacy related concerns.

   The Public Homenet Zone contains a full description of the services
   hosted in the network.  These services may not be expected to be
   publicly shared although their names remain accessible through the
   Internet.  Even though DNS makes information public, the DNS does not
   expect to make the complete list of services public.  In fact, making
   information public still requires the key (or FQDN) of each service
   to be known by the resolver in order to retrieve information about
   the services.  More specifically, making mywebsite.example.com public
   in the DNS, is not sufficient to make resolvers aware of the
   existence web site.  However, an attacker may walk the reverse DNS
   zone, or use other reconnaissance techniques to learn this
   information as described in [RFC7707].

   In order to prevent the complete Public Homenet Zone being published
   on the Internet, AXFR queries SHOULD be blocked on the Public
   Authoritative Server(s).  Similarly, to avoid zone-walking NSEC3
   [RFC5155] SHOULD be preferred over NSEC [RFC4034].  When the Public
   Homenet Zone is outsourced, the end user should be aware that it
   provides a complete description of the services available on the home
   network.  More specifically, names usually provides a clear
   indication of the service and possibly even the device type, and as
   the Public Homenet Zone contains the IP addresses associated with the
   service, they also limit the scope of the scan space.

   In addition to the Public Homenet Zone, the third party can also
   monitor the traffic associated with the Public Homenet Zone.  This
   traffic may provide an indication of the services an end user
   accesses, plus how and when they use these services.  Although,
   caching may obfuscate this information inside the home network, it is
   likely that outside your home network this information will not be
   cached.



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14.  Security Considerations

   The Homenet Naming Architecture described in this document solves
   exposing the HNA's DNS service as a DoS attack vector.

14.1.  HNA DM channels

   The HNA DM channels are specified to include their own security
   mechanisms that are designed to provide the minimum attacke surface,
   and to authenticate transactions where necessary.

14.2.  Names are less secure than IP addresses

   This document describes how an end user can make their services and
   devices from his home network reachable on the Internet by using
   names rather than IP addresses.  This exposes the home network to
   attackers, since names are expected to include less entropy than IP
   addresses.  In fact, with IP addresses, the Interface Identifier is
   64 bits long leading to up to 2^64 possibilities for a given
   subnetwork.  This is not to mention that the subnet prefix is also of
   64 bits long, thus providing up to 2^64 possibilities.  On the other
   hand, names used either for the home network domain or for the
   devices present less entropy (livebox, router, printer, nicolas,
   jennifer, ...) and thus potentially exposes the devices to dictionary
   attacks.

14.3.  Names are less volatile than IP addresses

   IP addresses may be used to locate a device, a host or a service.
   However, home networks are not expected to be assigned a time
   invariant prefix by ISPs.  As a result, observing IP addresses only
   provides some ephemeral information about who is accessing the
   service.  On the other hand, names are not expected to be as volatile
   as IP addresses.  As a result, logging names over time may be more
   valuable than logging IP addresses, especially to profile an end
   user's characteristics.

   PTR provides a way to bind an IP address to a name.  In that sense,
   responding to PTR DNS queries may affect the end user's privacy.  For
   that reason end users may choose not to respond to PTR DNS queries
   and MAY instead return a NXDOMAIN response.

14.4.  DNS Reflection Attacks

   An attacker performs a reflection attack when it sends traffic to one
   or more intermediary nodes (reflectors), that in turn send back
   response traffic to the victim.  Motivations for using an
   intermediary node might be anonymity of the attacker, as well as



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   amplification of the traffic.  Typically, when the intermediary node
   is a DNSSEC server, the attacker sends a DNSSEC query and the victim
   is likely to receive a DNSSEC response.  This section analyzes how
   the different components may be involved as a reflector in a
   reflection attack.  Section 14.5 considers the Hidden Primary,
   Section 14.6 the Synchronization Server, and Section 14.7 the Public
   Authoritative Server(s).

14.5.  Reflection Attack involving the Hidden Primary

   With the specified architecture, the Hidden Primary is only expected
   to receive DNS queries of type SOA, AXFR or IXFR.  This section
   analyzes how these DNS queries may be used by an attacker to perform
   a reflection attack.

   DNS queries of type AXFR and IXFR use TCP and as such are less
   subject to reflection attacks.  This makes SOA queries the only
   remaining practical vector of attacks for reflection attacks, based
   on UDP.

   SOA queries are not associated with a large amplification factor
   compared to queries of type "ANY" or to query of non existing FQDNs.
   This reduces the probability a DNS query of type SOA will be involved
   in a DDoS attack.

   SOA queries are expected to follow a very specific pattern, which
   makes rate limiting techniques an efficient way to limit such
   attacks, and associated impact on the naming service of the home
   network.

   Motivations for such a flood might be a reflection attack, but could
   also be a resource exhaustion attack performed against the Hidden
   Primary.  The Hidden Primary only expects to exchange traffic with
   the DM, that is its associated secondary.  Even though secondary
   servers may be renumbered as mentioned in Section 11, the Hidden
   Primary is likely to perform a DNSSEC resolution and find out the
   associated secondary's IP addresses in use.  As a result, the Hidden
   Primary is likely to limit the origin of its incoming traffic based
   on the origin IP address.

   With filtering rules based on IP address, SOA flooding attacks are
   limited to forged packets with the IP address of the secondary
   server.  In other words, the only victims are the Hidden Primary
   itself or the secondary.  There is a need for the Hidden Primary to
   limit that flood to limit the impact of the reflection attack on the
   secondary, and to limit the resource needed to carry on the traffic
   by the HNA hosting the Hidden Primary.  On the other hand, mitigation




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   should be performed appropriately, so as to limit the impact on the
   legitimate SOA sent by the secondary.

   The main reason for the DM sending a SOA query is to update the SOA
   RRset after the TTL expires, to check the serial number upon the
   receipt of a NOTIFY query from the Hidden Primary, or to re-send the
   SOA request when the response has not been received.  When a flood of
   SOA queries is received by the Hidden Primary, the Hidden Primary may
   assume it is involved in an attack.

   There are few legitimate time slots when the secondary is expected to
   send a SOA query.  Suppose T_NOTIFY is the time a NOTIFY is sent by
   the Hidden Primary, T_SOA the last time the SOA has been queried, TTL
   the TTL associated to the SOA, and T_REFRESH the refresh time defined
   in the SOA RRset.  The specific time SOA queries are expected can be
   for example T_NOTIFY, T_SOA + 2/3 TTL, T_SOA + TTL, T_SOA +
   T_REFRESH., and.  Outside a few minutes following these specific time
   slots, the probability that the HNA discards a legitimate SOA query
   is very low.  Within these time slots, the probability the secondary
   may have its legitimate query rejected is higher.  If a legitimate
   SOA is discarded, the secondary will re-send SOA query every "retry
   time" second until "expire time" seconds occurs, where "retry time"
   and "expire time" have been defined in the SOA.

   As a result, it is RECOMMENDED to set rate limiting policies to
   protect HNA resources.  If a flood lasts more than the expired time
   defined by the SOA, it is RECOMMENDED to re-initiate a
   synchronization between the Hidden Primary and the secondaries.

14.6.  Reflection Attacks involving the DM

   The DM acts as a secondary coupled with the Hidden Primary.  The
   secondary expects to receive NOTIFY query, SOA responses, AXFR and
   IXFR responses from the Hidden Primary.

   Sending a NOTIFY query to the secondary generates a NOTIFY response
   as well as initiating an SOA query exchange from the secondary to the
   Hidden Primary.  As mentioned in [RFC1996], this is a known "benign
   denial of service attack".  As a result, the DM SHOULD enforce rate
   limiting on sending SOA queries and NOTIFY responses to the Hidden
   Primary.  Most likely, when the secondary is flooded with valid and
   signed NOTIFY queries, it is under a replay attack which is discussed
   in Section 14.9.  The key thing here is that the secondary is likely
   to be designed to be able to process much more traffic than the
   Hidden Primary hosted on a HNA.

   This paragraph details how the secondary may limit the NOTIFY
   queries.  Because the Hidden Primary may be renumbered, the secondary



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   SHOULD NOT perform permanent IP filtering based on IP addresses.  In
   addition, a given secondary may be shared among multiple Hidden
   Primaries which make filtering rules based on IP harder to set.  The
   time at which a NOTIFY is sent by the Hidden Primary is not
   predictable.  However, a flood of NOTIFY messages may be easily
   detected, as a NOTIFY originated from a given Homenet Zone is
   expected to have a very limited number of unique source IP addresses,
   even when renumbering is occurring.  As a result, the secondary, MAY
   rate limit incoming NOTIFY queries.

   On the Hidden Primary side, it is recommended that the Hidden Primary
   sends a NOTIFY as long as the zone has not been updated by the
   secondary.  Multiple SOA queries may indicate the secondary is under
   attack.

14.7.  Reflection Attacks involving the Public Authoritative Servers

   Reflection attacks involving the Public Authoritative Server(s) are
   similar to attacks on any Outsourcing Infrastructure.  This is not
   specific to the architecture described in this document, and thus are
   considered as out of scope.

   In fact, one motivation of the architecture described in this
   document is to expose the Public Authoritative Server(s) to attacks
   instead of the HNA, as it is believed that the Public Authoritative
   Server(s) will be better able to defend itself.

14.8.  Flooding Attack

   The purpose of flooding attacks is mostly resource exhaustion, where
   the resource can be bandwidth, memory, or CPU for example.

   One goal of the architecture described in this document is to limit
   the surface of attack on the HNA.  This is done by outsourcing the
   DNS service to the Public Authoritative Server(s).  By doing so, the
   HNA limits its DNS interactions between the Hidden Primary and the
   DM.  This limits the number of entities the HNA interacts with as
   well as the scope of DNS exchanges - NOTIFY, SOA, AXFR, IXFR.

   The use of an authenticated channel with SIG(0) or TSIG between the
   HNA and the DM, enables detection of illegitimate DNS queries, so
   appropriate action may be taken - like dropping the queries.  If
   signatures are validated, then most likely, the HNA is under a replay
   attack, as detailed in Section 14.9

   In order to limit the resource required for authentication, it is
   recommended to use TSIG that uses symmetric cryptography over SIG(0)
   that uses asymmetric cryptography.



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14.9.  Replay Attack

   Replay attacks consist of an attacker either resending or delaying a
   legitimate message that has been sent by an authorized user or
   process.  As the Hidden Primary and the DM use an authenticated
   channel, replay attacks are mostly expected to use forged DNS queries
   in order to provide valid traffic.

   From the perspective of an attacker, using a correctly authenticated
   DNS query may not be detected as an attack and thus may generate a
   response.  Generating and sending a response consumes more resources
   than either dropping the query by the defender, or generating the
   query by the attacker, and thus could be used for resource exhaustion
   attacks.  In addition, as the authentication is performed at the DNS
   layer, the source IP address could be impersonated in order to
   perform a reflection attack.

   Section 14.4 details how to mitigate reflection attacks and
   Section 14.8 details how to mitigate resource exhaustion.  Both
   sections assume a context of DoS with a flood of DNS queries.  This
   section suggests a way to limit the attack surface of replay attacks.

   As SIG(0) and TSIG use inception and expiration time, the time frame
   for replay attack is limited.  SIG(0) and TSIG recommends a fudge
   value of 5 minutes.  This value has been set as a compromise between
   possibly loose time synchronization between devices and the valid
   lifetime of the message.  As a result, better time synchronization
   policies could reduce the time window of the attack.

   [](<!- <section title="DNSSEC is recommended to authenticate DNS
   hosted data

   Deploying DNSSEC is recommended, since in some cases the information
   stored in the DNS is used by the ISP or an IT department to grant
   access.  For example some servers may perform PTR DNS queries to
   grant access based on host names.  DNSSEC mitigates lack of trust in
   DNS, and it is RECOMMENDED to deploy DNSSEC on HNAs.

       -->)

15.  IANA Considerations

   This document has no actions for IANA.








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16.  Acknowledgment

   The authors wish to thank Philippe Lemordant for its contributions on
   the early versions of the draft; Ole Troan for pointing out issues
   with the IPv6 routed home concept and placing the scope of this
   document in a wider picture; Mark Townsley for encouragement and
   injecting a healthy debate on the merits of the idea; Ulrik de Bie
   for providing alternative solutions; Paul Mockapetris, Christian
   Jacquenet, Francis Dupont and Ludovic Eschard for their remarks on
   HNA and low power devices; Olafur Gudmundsson for clarifying DNSSEC
   capabilities of small devices; Simon Kelley for its feedback as
   dnsmasq implementer; Andrew Sullivan, Mark Andrew, Ted Lemon, Mikael
   Abrahamson, Michael Richardson and Ray Bellis for their feedback on
   handling different views as well as clarifying the impact of
   outsourcing the zone signing operation outside the HNA; Mark Andrew
   and Peter Koch for clarifying the renumbering.

17.  Annex

17.1.  Envisioned deployment scenarios

   A number of deployment have been envisionned, this section aims at
   providing a brief description.  The use cases are not limitatives and
   this section is not normative.

17.1.1.  CPE Vendor

   A specific vendor with specific relations with a registrar or a
   registry may sell a CPE that is provisioned with provisioned domain
   name.  Such domain name does not need to be necessary human readable.

   One possible way is that the vendor also provisions the HNA with a
   private and public keys as well as a certificate.  Note that these
   keys are not expected to be used for DNSSEC signing.  Instead these
   keys are solely used by the HNA to proceed to the authentication.
   Normally the keys should be necessary and sufficient to proceed to
   the authentication.  The reason to combine the domain name and the
   key is that outsourcing infrastructure are likely handle names better
   than keys and that domain names might be used as a login which
   enables the key to be regenerated.

   When the home network owner plugs the CPE at home, the relation
   between HNA and DM is expected to work out-of-the-box.








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17.1.2.  Agnostic CPE

   An CPE that is not preconfigured may also take advanatge to the
   protocol defined in this document but some configuration steps will
   be needed.

   1.  The owner of the home network buys a domain name to a registrar,
       and as such creates an account on that registrar

   2.  Either the registrar is also providing the outsourcing
       infrastructure or the home network needs to create a specific
       account on the outsourcing infrastructure.  * If the outsourcing
       provider is the registrar, the outsourcing has by design a proof
       of ownership of the domain name by the homenet owner.  In this
       case, it is expected the infrastructure provides the necessary
       parameters to the home network owner to configure the HNA.  A
       good way to provide the parameters would be the home network be
       able to copy/paste a JSON object.  What matters at that point is
       the outsourcing infrastructure being able to generate
       authentication credentials for the HNA to authenticate itself to
       the outsourcing infrastructure.  This obviously requires the home
       network to provide the public key gnerated by the HNA in a CSR.

   o  If the outsourcing infrastructure is not the registrar, then the
      proof of ownership needs to be established using protocols like
      ACME for example that will end in the generation of a certificate.
      ACME is used here to the purpose of automating the generation of
      the certificate, the CA may be a specific CA or the outsourcing
      infrastructure.  With that being done, the outsourcing
      infrastructure has a roof of ownership and can proceed as above.

17.2.  Example: Homenet Zone

   This section is not normative and intends to illustrate how the HNA
   builds the Homenet Zone.

   As depicted in Figure 1, the Public Homenet Zone is hosted on the
   Public Authoritative Server(s), whereas the Homenet Zone is hosted on
   the HNA.  This section considers that the HNA builds the zone that
   will be effectively published on the Public Authoritative Server(s).
   In other words "Homenet to Public Zone transformation" is the
   identity also commonly designated as "no operation" (NOP).

   In that case, the Homenet Zone should configure its Name Server RRset
   (NS) and Start of Authority (SOA) with the values associated with the
   Public Authoritative Server(s).  This is illustrated in Figure 2.
   public.primary.example.net is the FQDN of the Public Authoritative
   Server(s), and IP1, IP2, IP3, IP4 are the associated IP addresses.



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   Then the HNA should add the additional new nodes that enter the home
   network, remove those that should be removed, and sign the Homenet
   Zone.

   $ORIGIN example.com
   $TTL 1h

   @  IN  SOA  public.primary.example.net
          hostmaster.example.com. (
          2013120710 ; serial number of this zone file
          1d         ; secondary refresh
          2h         ; secondary retry time in case of a problem
          4w         ; secondary expiration time
          1h         ; maximum caching time in case of failed
                     ; lookups
          )

   @   NS  public.authoritative.servers.example.net

   public.primary.example.net   A @IP1
   public.primary.example.net   A @IP2
   public.primary.example.net   AAAA @IP3
   public.primary.example.net   AAAA @IP4

                          Figure 2: Homenet Zone

   The SOA RRset is defined in [RFC1033], [RFC1035] and [RFC2308].  This
   SOA is specific, as it is used for the synchronization between the
   Hidden Primary and the DM and published on the DNS Public
   Authoritative Server(s)..

   o  MNAME: indicates the primary.  In our case the zone is published
      on the Public Authoritative Server(s), and its name MUST be
      included.  If multiple Public Authoritative Server(s) are
      involved, one of them MUST be chosen.  More specifically, the HNA
      MUST NOT include the name of the Hidden Primary.

   o  RNAME: indicates the email address to reach the administrator.
      [RFC2142] recommends using hostmaster@domain and replacing the '@'
      sign by '.'.

   o  REFRESH and RETRY: indicate respectively in seconds how often
      secondaries need to check the primary, and the time between two
      refresh when a refresh has failed.  Default values indicated by
      [RFC1033] are 3600 (1 hour) for refresh and 600 (10 minutes) for
      retry.  This value might be too long for highly dynamic content.
      However, the Public Authoritative Server(s) and the HNA are
      expected to implement NOTIFY [RFC1996].  So whilst shorter refresh



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      timers might increase the bandwidth usage for secondaries hosting
      large number of zones, it will have little practical impact on the
      elapsed time required to achieve synchronization between the
      Outsourcing Infrastructure and the Hidden Master.  As a result,
      the default values are acceptable.

   o  EXPIRE: is the upper limit data SHOULD be kept in absence of
      refresh.  The default value indicated by [RFC1033] is 3600000
      (approx. 42 days).  In home network architectures, the HNA
      provides both the DNS synchronization and the access to the home
      network.  This device may be plugged and unplugged by the end user
      without notification, thus we recommend a long expiry timer.

   o  MINIMUM: indicates the minimum TTL.  The default value indicated
      by [RFC1033] is 86400 (1 day).  For home network, this value MAY
      be reduced, and 3600 (1 hour) seems more appropriate.

   <<!-- ## Considerations on multiple Registered Homenet Domain Names
   ## are left for future versions When multiple Registered Homenet
   Domains are used -like example.com, example.net, example.org, a DNS
   Homenet Zone file per Registered Homenet Domain SHOULD be generated.
   In order to synchronize the zone contents, the HNA may provide all
   bindings in each zone files.  As a result, any update MUST be
   performed on all zone files, i.e. for all Registered Homenet Domains.
   To limit thees updates when multiple Registered Homenet Domains are
   involved, the HNA MAY fill all bindings in a specific zone file and
   redirect all other zones to that zone.  This can be achieved with
   redirecting mechanisms like CNAME {{RFC2181}}, {{RFC1034}}, DNAME
   {{RFC6672}} or CNAME+DNAME {{I-D.sury-dnsext-cname-dname}}. This is
   an implementation issue to determine whether redirection mechanisms
   MAY be preferred for large Homenet Zones, or when the number of
   Registered Homenet Domain becomes quite large. -->>

17.3.  Example: HNA necessary parameters for outsourcing

   This section specifies the various parameters required by the HNA to
   configure the naming architecture of this document.  This section is
   informational, and is intended to clarify the information handled by
   the HNA and the various settings to be done.

   DM may be configured with the following parameters.  These parameters
   are necessary to establish a secure channel between the HNA and the
   DM as well as to specify the DNS zone that is in the scope of the
   communication:

   o  DM: The associated FQDNs or IP addresses of the DM.  IP addresses
      are optional and the FQDN is sufficient.  To secure the binding




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      name and IP addresses, a DNSSEC exchange is required.  Otherwise,
      the IP addresses should be entered manually.

   o  Authentication Method: How the HNA authenticates itself to the DM.
      This MAY depend on the implementation but this should cover at
      least IPsec, DTLS and TSIG

   o  Authentication data: Associated Data.  PSK only requires a single
      argument.  If other authentication mechanisms based on
      certificates are used, then HNA private keys, certificates and
      certification authority should be specified.

   o  Public Authoritative Server(s): The FQDN or IP addresses of the
      Public Authoritative Server(s).  It MAY correspond to the data
      that will be set in the NS RRsets and SOA of the Homenet Zone.  IP
      addresses are optional and the FQDN is sufficient.  To secure the
      binding between name and IP addresses, a DNSSEC exchange is
      required.  Otherwise, the IP addresses should be entered manually.

   o  Registered Homenet Domain: The domain name used to establish the
      secure channel.  This name is used by the DM and the HNA for the
      primary / secondary configuration as well as to index the NOTIFY
      queries of the HNA when the HNA has been renumbered.



     Setting the Homenet Zone requires the following information.

   o  Registered Homenet Domain: The Domain Name of the zone.  Multiple
      Registered Homenet Domains may be provided.  This will generate
      the creation of multiple Public Homenet Zones.

   o  Public Authoritative Server(s): The Public Authoritative Server(s)
      associated with the Registered Homenet Domain.  Multiple Public
      Authoritative Server(s) may be provided.

   Two possible methods of providing the required information would be:

   JSON for forward zones [should be standardized in a similar way to
   zone file layout in RFC1035]

   DHCP for reverse zones [needs a separate draft]

18.  References







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18.1.  Normative References

   [RFC1033]  Lottor, M., "Domain Administrators Operations Guide",
              RFC 1033, DOI 10.17487/RFC1033, November 1987,
              <https://www.rfc-editor.org/info/rfc1033>.

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
              <https://www.rfc-editor.org/info/rfc1034>.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
              November 1987, <https://www.rfc-editor.org/info/rfc1035>.

   [RFC1995]  Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995,
              DOI 10.17487/RFC1995, August 1996,
              <https://www.rfc-editor.org/info/rfc1995>.

   [RFC1996]  Vixie, P., "A Mechanism for Prompt Notification of Zone
              Changes (DNS NOTIFY)", RFC 1996, DOI 10.17487/RFC1996,
              August 1996, <https://www.rfc-editor.org/info/rfc1996>.

   [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>.

   [RFC2136]  Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,
              "Dynamic Updates in the Domain Name System (DNS UPDATE)",
              RFC 2136, DOI 10.17487/RFC2136, April 1997,
              <https://www.rfc-editor.org/info/rfc2136>.

   [RFC2142]  Crocker, D., "Mailbox Names for Common Services, Roles and
              Functions", RFC 2142, DOI 10.17487/RFC2142, May 1997,
              <https://www.rfc-editor.org/info/rfc2142>.

   [RFC2181]  Elz, R. and R. Bush, "Clarifications to the DNS
              Specification", RFC 2181, DOI 10.17487/RFC2181, July 1997,
              <https://www.rfc-editor.org/info/rfc2181>.

   [RFC2308]  Andrews, M., "Negative Caching of DNS Queries (DNS
              NCACHE)", RFC 2308, DOI 10.17487/RFC2308, March 1998,
              <https://www.rfc-editor.org/info/rfc2308>.

   [RFC2845]  Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
              Wellington, "Secret Key Transaction Authentication for DNS
              (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000,
              <https://www.rfc-editor.org/info/rfc2845>.



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   [RFC2931]  Eastlake 3rd, D., "DNS Request and Transaction Signatures
              ( SIG(0)s )", RFC 2931, DOI 10.17487/RFC2931, September
              2000, <https://www.rfc-editor.org/info/rfc2931>.

   [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Resource Records for the DNS Security Extensions",
              RFC 4034, DOI 10.17487/RFC4034, March 2005,
              <https://www.rfc-editor.org/info/rfc4034>.

   [RFC4192]  Baker, F., Lear, E., and R. Droms, "Procedures for
              Renumbering an IPv6 Network without a Flag Day", RFC 4192,
              DOI 10.17487/RFC4192, September 2005,
              <https://www.rfc-editor.org/info/rfc4192>.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
              December 2005, <https://www.rfc-editor.org/info/rfc4301>.

   [RFC4555]  Eronen, P., "IKEv2 Mobility and Multihoming Protocol
              (MOBIKE)", RFC 4555, DOI 10.17487/RFC4555, June 2006,
              <https://www.rfc-editor.org/info/rfc4555>.

   [RFC4960]  Stewart, R., Ed., "Stream Control Transmission Protocol",
              RFC 4960, DOI 10.17487/RFC4960, September 2007,
              <https://www.rfc-editor.org/info/rfc4960>.

   [RFC5155]  Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
              Security (DNSSEC) Hashed Authenticated Denial of
              Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008,
              <https://www.rfc-editor.org/info/rfc5155>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <https://www.rfc-editor.org/info/rfc5246>.

   [RFC5936]  Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol
              (AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010,
              <https://www.rfc-editor.org/info/rfc5936>.

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
              January 2012, <https://www.rfc-editor.org/info/rfc6347>.

   [RFC6644]  Evans, D., Droms, R., and S. Jiang, "Rebind Capability in
              DHCPv6 Reconfigure Messages", RFC 6644,
              DOI 10.17487/RFC6644, July 2012,
              <https://www.rfc-editor.org/info/rfc6644>.



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   [RFC6672]  Rose, S. and W. Wijngaards, "DNAME Redirection in the
              DNS", RFC 6672, DOI 10.17487/RFC6672, June 2012,
              <https://www.rfc-editor.org/info/rfc6672>.

   [RFC6762]  Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
              DOI 10.17487/RFC6762, February 2013,
              <https://www.rfc-editor.org/info/rfc6762>.

   [RFC6763]  Cheshire, S. and M. Krochmal, "DNS-Based Service
              Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
              <https://www.rfc-editor.org/info/rfc6763>.

   [RFC7010]  Liu, B., Jiang, S., Carpenter, B., Venaas, S., and W.
              George, "IPv6 Site Renumbering Gap Analysis", RFC 7010,
              DOI 10.17487/RFC7010, September 2013,
              <https://www.rfc-editor.org/info/rfc7010>.

   [RFC7296]  Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
              Kivinen, "Internet Key Exchange Protocol Version 2
              (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
              2014, <https://www.rfc-editor.org/info/rfc7296>.

   [RFC7344]  Kumari, W., Gudmundsson, O., and G. Barwood, "Automating
              DNSSEC Delegation Trust Maintenance", RFC 7344,
              DOI 10.17487/RFC7344, September 2014,
              <https://www.rfc-editor.org/info/rfc7344>.

   [RFC7368]  Chown, T., Ed., Arkko, J., Brandt, A., Troan, O., and J.
              Weil, "IPv6 Home Networking Architecture Principles",
              RFC 7368, DOI 10.17487/RFC7368, October 2014,
              <https://www.rfc-editor.org/info/rfc7368>.

   [RFC7558]  Lynn, K., Cheshire, S., Blanchet, M., and D. Migault,
              "Requirements for Scalable DNS-Based Service Discovery
              (DNS-SD) / Multicast DNS (mDNS) Extensions", RFC 7558,
              DOI 10.17487/RFC7558, July 2015,
              <https://www.rfc-editor.org/info/rfc7558>.

   [RFC7707]  Gont, F. and T. Chown, "Network Reconnaissance in IPv6
              Networks", RFC 7707, DOI 10.17487/RFC7707, March 2016,
              <https://www.rfc-editor.org/info/rfc7707>.

   [RFC7788]  Stenberg, M., Barth, S., and P. Pfister, "Home Networking
              Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April
              2016, <https://www.rfc-editor.org/info/rfc7788>.






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   [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>.

   [RFC8375]  Pfister, P. and T. Lemon, "Special-Use Domain
              'home.arpa.'", RFC 8375, DOI 10.17487/RFC8375, May 2018,
              <https://www.rfc-editor.org/info/rfc8375>.

18.2.  Informative References

   [I-D.howard-dnsop-ip6rdns]
              Howard, L., "Reverse DNS in IPv6 for Internet Service
              Providers", draft-howard-dnsop-ip6rdns-00 (work in
              progress), June 2014.

   [I-D.ietf-homenet-naming-architecture-dhc-options]
              Migault, D., Mrugalski, T., Griffiths, C., Weber, R., and
              W. Cloetens, "DHCPv6 Options for Homenet Naming
              Architecture", draft-ietf-homenet-naming-architecture-dhc-
              options-06 (work in progress), June 2018.

   [I-D.ietf-homenet-simple-naming]
              Lemon, T., Migault, D., and S. Cheshire, "Homenet Naming
              and Service Discovery Architecture", draft-ietf-homenet-
              simple-naming-03 (work in progress), October 2018.

   [I-D.sury-dnsext-cname-dname]
              Sury, O., "CNAME+DNAME Name Redirection", draft-sury-
              dnsext-cname-dname-00 (work in progress), April 2010.

Authors' Addresses

   Daniel Migault
   Ericsson
   8275 Trans Canada Route
   Saint Laurent, QC  4S 0B6
   Canada

   EMail: daniel.migault@ericsson.com











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   Ralf Weber
   Nominum
   2000 Seaport Blvd
   Redwood City  94063
   US

   EMail: ralf.weber@nominum.com


   Michael Richardson
   Sandelman Software Works
   470 Dawson Avenue
   Ottawa, ON  K1Z 5V7
   Canada

   EMail: mcr+ietf@sandelman.ca


   Ray Hunter
   Globis Consulting BV
   Weegschaalstraat 3
   Eindhoven  5632CW
   NL

   EMail: v6ops@globis.net


   Chris Griffiths

   EMail: cgriffiths@gmail.com


   Wouter Cloetens
   SoftAtHome
   vaartdijk 3 701
   Wijgmaal  3018
   BE

   EMail: wouter.cloetens@softathome.com












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