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Versions: (draft-mglt-homenet-naming-architecture-dhc-options) 00 01 02 03 04 05 06

HOMENET                                                  D. Migault (Ed)
Internet-Draft                                                  Ericsson
Intended status: Standards Track                             W. Cloetens
Expires: November 20, 2015                                    SoftAtHome
                                                            C. Griffiths
                                                                     Dyn
                                                                R. Weber
                                                                 Nominum
                                                            May 19, 2015


              DHCP Options for Homenet Naming Architecture
       draft-ietf-homenet-naming-architecture-dhc-options-02.txt

Abstract

   CPEs are usually constraint devices with reduced network and CPU
   capacities.  As such, a CPE hosting on the Internet the authoritative
   naming service for its home network may become vulnerable to resource
   exhaustion attacks.  One way to avoid exposing CPE is to outsource
   the authoritative service to a third party.  This third party can be
   the ISP or any other independent third party.

   Outsourcing the authoritative naming service to a third party
   requires setting up an architecture which may be unappropriated for
   most end users.  To leverage this issue, this document proposes DHCP
   Options so any agnostic CPE can automatically proceed to the
   appropriated configuration and outsource the authoritative naming
   service for the home network.  This document shows that in most
   cases, these DHCP Options make outsourcing to a third party (be it
   the ISP or any ISP independent service provider) transparent for the
   end user.

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 http://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 November 20, 2015.

Copyright Notice

   Copyright (c) 2015 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
   (http://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.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Protocol Overview . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Architecture and DHCP Options Overview  . . . . . . . . .   7
     4.2.  Mechanisms Securing DNS Transactions  . . . . . . . . . .  10
     4.3.  Primary / Secondary Synchronization versus DNS Update . .  11
   5.  CPE Configuration . . . . . . . . . . . . . . . . . . . . . .  11
     5.1.  CPE Primary / Secondary Synchronization Configurations  .  11
       5.1.1.  CPE / Public Authoritative Name Server Set  . . . . .  12
       5.1.2.  CPE / Reverse Public Authoritative Name Server Set  .  12
     5.2.  CPE DNS Data Handling and Update Policies . . . . . . . .  12
       5.2.1.  DNS Homenet Zone Template . . . . . . . . . . . . . .  12
       5.2.2.  DNS (Reverse) Homenet Zone  . . . . . . . . . . . . .  13
   6.  Payload Description . . . . . . . . . . . . . . . . . . . . .  13
     6.1.  Security Field  . . . . . . . . . . . . . . . . . . . . .  14
     6.2.  Update Field  . . . . . . . . . . . . . . . . . . . . . .  14
     6.3.  DHCP Public Key Option  . . . . . . . . . . . . . . . . .  15
     6.4.  DHCP Zone Template Option . . . . . . . . . . . . . . . .  16
     6.5.  DHCP Public Authoritative Name Server Set Option  . . . .  16
     6.6.  DHCP Reverse Public Authoritative Name Server Set Option   17
   7.  DHCP Behavior . . . . . . . . . . . . . . . . . . . . . . . .  18
     7.1.  DHCPv6 Server Behavior  . . . . . . . . . . . . . . . . .  18
     7.2.  DHCPv6 Client Behavior  . . . . . . . . . . . . . . . . .  19
     7.3.  DHCPv6 Relay Behavior . . . . . . . . . . . . . . . . . .  19
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  19
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  19
     9.1.  DNSSEC is recommended to authenticate DNS hosted data . .  19
     9.2.  Channel between the CPE and ISP DHCP Server MUST be



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           secured . . . . . . . . . . . . . . . . . . . . . . . . .  19
     9.3.  CPEs are sensitive to DoS . . . . . . . . . . . . . . . .  20
   10. Acknowledgment  . . . . . . . . . . . . . . . . . . . . . . .  20
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  20
     11.2.  Informational References . . . . . . . . . . . . . . . .  22
   Appendix A.  Scenarios and impact on the End User . . . . . . . .  22
     A.1.  Base Scenario . . . . . . . . . . . . . . . . . . . . . .  22
     A.2.  Third Party Registered Homenet Domain . . . . . . . . . .  23
     A.3.  Third Party DNS Infrastructure  . . . . . . . . . . . . .  23
     A.4.  Multiple ISPs . . . . . . . . . . . . . . . . . . . . . .  25
   Appendix B.  Document Change Log  . . . . . . . . . . . . . . . .  26
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27

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.  Terminology

   - Customer Premises Equipment:   (CPE) is the router providing
         connectivity to the home network.  It is configured and managed
         by the end user.  In this document, the CPE might also hosts
         services such as DHCPv6.  This device might be provided by the
         ISP.

   - Public Key:   designates a public Key generated by the CPE.  This
         key is used as an authentication credential for the CPE.

   - Registered Homenet Domain:   is the Domain Name associated to the
         home network.

   - DNS Homenet Zone:   is the DNS zone associated to the home network.
         This zone is set by the CPE and essentially contains the
         bindings between names and IP addresses of the nodes of the
         home network.  In this document, the CPE does neither perform
         any DNSSEC management operations such as zone signing nor
         provide an authoritative service for the zone.  Both are
         delegated to the Public Authoritative Server.  The CPE
         synchronizes the DNS Homenet Zone with the Public Authoritative
         Server via a hidden primary / secondary architecture.  The
         Public Authoritative Server might use specific servers for the
         synchronization of the DNS Homenet Zone: the Public
         Authoritative Name Server Set.





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   - DNS Homenet Zone Template:   The template used as a basis to
         generate the DNS Homenet Zone.

   - DNS Template Server:   The DNS server that hosts the DNS Homenet
         Zone Template.

   - DNS Homenet Reverse Zone:   The reverse zone file associated to the
         DNS Homenet Zone.

   - Public Authoritative Primary(ies):   are the visible name server
         hosting the DNS Homenet Zone.  End users' resolutions for the
         Homenet Domain are sent to this server, and this server is a
         primary for the zone.

   - Public Authoritative Name Server Set:   is the server the CPE
         synchronizes the DNS Homenet Zone.  It is configured as a
         secondary and the CPE acts as primary.  The CPE sends
         information so the DNSSEC zone can be set and served.

   - Reverse Public Authoritative Primary(ies):   are the visible name
         server hosting the DNS Homenet Reverse Zone.  End users'
         resolutions for the Homenet Domain are sent to this server, and
         this server is a primary for the zone.

   - Reverse Public Authoritative Name Server Set:   is the server the
         CPE synchronizes the DNS Homenet Reverse Zone.  It is
         configured as a secondary and the CPE acts as primary.  The CPE
         sends information so the DNSSEC zone can be set and served.

3.  Introduction

   CPEs are usually constraint devices with reduced network and CPU
   capacities.  As such, a CPE hosting on the Internet the authoritative
   naming service for its home network may become vulnerable to resource
   exhaustion attacks.  One way to avoid exposing CPE is to outsource
   the authoritative service to a third party.  This third party can be
   the ISP or any other independent third party.

   Outsourcing the authoritative naming service to a third party
   requires setting up an architecture which may be unappropriated for
   most end users.  To leverage this issue, this document proposes DHCP
   Options so any agnostic CPE can automatically proceed to the
   appropriated configuration and outsource the authoritative naming
   service for the home network.  This document shows that in most
   cases, these DHCP Options make outsourcing to a third party (be it
   the ISP or any ISP independent service provider) transparent for the
   end user.




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   When the CPE is plugged, the DHCP Options described in the document
   enable the CPE:

   - 1.  To build the DNS Homenet Zone: Building the DNS Homenet Zone
         requires filling the zone with appropriated bindings likes name
         / IP addresses of the different devices in the home networks.
         Such information can be provided for example by the DHCP Server
         hosted on the CPE.  On the other hand, it also requires
         configuration parameters like the name of the Registered Domain
         Name associated to the home network or the Public Authoritative
         Primary(ies) the DNS Homenet Zone is outsourced to.  These
         configuration parameters are stored in the DNS Homenet Zone
         Template.  This document describes the DHCP Zone Template
         Option.  This option carries a DNS Homenet Zone Template FQDN.
         In order to retrieve the DNS Homenet Zone Template, the CPE
         sends a query of type AXFR [RFC1034] [RFC5936]for the DNS
         Homenet Zone Template FQDN.

   - 2.  To upload the DNS(SEC) Homenet Zone to the appropriated server:
         This server is designated as the Public Authoritative Name
         Server Set. It is in charge of publishing the DNS(SEC) Homenet
         Zone on the Public Authoritative Primary(ies).  This document
         describes the DHCP Public Authoritative Name Server Set Option
         that provides the FQDN of the appropriated server.  Note that,
         in the document we do not consider whether the DNS(SEC) Homenet
         Zone is signed or not and if signed who signs it.  Such
         questions are out of the scope of the current document.

   - 3.  To upload the DNS Homenet Reverse Zone to the appropriated
         server: This server is designated as the Reverse Public
         Authoritative Name Server Set. It is in charge of publishing
         the DNS Homenet Reverse Zone on the Reverse Public
         Authoritative Primary(ies).  This document describes the DHCP
         Reverse Public Authoritative Name Server Set Option that
         provides the FQDN of the appropriated server.  Similarly to
         item 2., we do not consider in this document if the DNS Homenet
         Reverse Zone is signed or not, and if signed who signs it.

   - 4.  To provide authentication credential (a public key) to the DHCP
         Server: Information stored in the DNS Homenet Zone Template,
         the DNS(SEC) Homenet Zone and DNS Homenet Reverse Zone belongs
         to the CPE, and only the CPE should be able to update or upload
         these zones.  To authenticate the CPE, this document defines
         the DHCP Public Key Option.  This option is sent by the CPE to
         the DHCP Server and provides the Public Key the CPE uses to
         authenticate itself.  The DHCP Server is then responsible to
         provide the Public Key to the various DNS servers.




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   As a result, the DHCP Options described in this document enable an
   agnostic CPE to outsource its naming infrastructure without any
   configuration from the end user.  The main reason no configuration is
   required by the end user is that there are privileged links: first
   between the CPE and the DHCP Server and then between the DHCP Server
   and the various DNS servers (DNS Homenet Zone Server, the Reverse
   Public Authoritative Name Server Set, Public Authoritative Name
   Server Set).  This enables the CPE to send its authentication
   credentials (a Public Key) to the DHCP Server that in turn forward it
   to the various DNS servers.  With the authentication credential on
   the DNS servers set, the CPE is able to update the various zones in a
   secure way.

   If the DHCP Server cannot provide the public key to one of these
   servers (most likely the Public Authoritative Name Server Set) and
   the CPE needs to interact with the server, then, the end user is
   expected to provide the CPE's public key to these servers (the
   Reverse Public Authoritative Name Server Set or the Public
   Authoritative Name Server Set) either manually or using other
   mechanisms.  Such mechanisms are outside the scope of this document.
   In that case, the authentication credentials need to be provided
   every time the key is modified.  Appendix A provides more details on
   how different scenarios impact the end users.

   The remaining of this document is as follows.  Section 4 provides an
   overview of the DHCP Options as well as the expected interactions
   between the CPE and the various involved entities.  This section also
   provides an overview of available mechanisms to secure DNS
   transactions and update DNS Data.  Section 5 describes how the CPE
   may securely synchronize and update DNS data.  Section 6 describes
   the payload of the DHCP Options and Section 7 details how DHCP Client
   DHCP Server and DHCP Relay behave.  Section 8 lists the new
   parameters to be registered at the IANA, Section 9 provides security
   considerations.  Finally, Appendix A describes how the CPE may behave
   and be configured regarding various scenarios.

4.  Protocol Overview

   This section provides an overview of the how the CPE is expect to
   interact with various entities, as well as how the CPE is expected to
   be configured via DHCP Options.  Section 4.1 describes the entities
   the CPE is expected to interact with.  Interaction with each entities
   is defined via DHCP Options that are expected to configure the CPE.
   Once configured, the CPE is expected to be able to update some DNS
   Data hosted by the different entities.  As a result security and
   updating mechanisms play an important role in the specification.
   Section 4.2 provides an overview of the different security mechanisms
   considered for securing the CPE transactions and Section 4.3



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   considers the different update mechanisms considered for the CPE to
   update the DNS Data.

4.1.  Architecture and DHCP Options Overview

   This section illustrates how a CPE configures its naming
   infrastructure to outsource its authoritative naming service.  All
   configurations and settings are performed using DHCP Options.  This
   section, for the sake of simplicity, assumes that the DHCP Server is
   able to communicate to the various DNS servers and to provide them
   the public key associated to the CPE.  Once each server got the
   public key, the CPE can proceed to updates in a authenticated and
   secure way.

   This scenario has been chosen as it is believed to be the most
   popular scenario.  This document does not ignore that scenarios where
   the DHCP Server does not have privileged relations with the Public
   Authoritative Name Server Set must be considered.  These cases are
   discussed latter in Appendix A.  Such scenario does not necessarily
   require configuration for the end user and can also be Zero Config.

   The scenario is represented in Figure 1.

   - 1:  The CPE provides its Public Key to the DHCP Server using a DHCP
         Public Key Option (OPTION_PUBLIC_KEY) and sends a DHCP Option
         Request Option (ORO) for the DHCP Zone Template Option
         (OPTION_DNS_ZONE_TEMPLATE), the DHCP Public Authoritative Name
         Server Set Option (OPTION_NAME_SERVER_SET) and the DHCP Reverse
         Public Authoritative Name Server Set Option
         (OPTION_REVERSE_NAME_SERVER_SET).

   - 2:  The DHCP Server makes the Public Key available to the DNS
         servers, so the CPE can secure its DNS transactions.  Note that
         the Public Key alone is not sufficient to perform the
         authentication and the key should be, for example, associated
         with an identifier, or the concerned domain name.  How the
         binding is performed is out of scope of the document.  It can
         be a centralized database or various bindings may be sent to
         the different servers.  Figure 1 represents the specific case
         were the DHCP Server forwards the set (Public Key, Zone
         Template FQDN) to the DNS Template Server, the set (Public Key,
         IPv6 subnet) to the Reverse Public Authoritative Name Server
         Set and the set (Public Key, Registered Homenet Domain) to the
         Public Authoritative Name Server Set.

   - 3.:   The DHCP Server responds to the CPE with the requested DHCP
         Options, i.e. the DHCP Public Key Option (OPTION_PUBLIC_KEY),
         DHCP Zone Template Option OPTION_DNS_ZONE_TEMPLATE, DHCP Public



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         Authoritative Name Server Set Option (OPTION_NAME_SERVER_SET),
         DHCP Reverse Public Authoritative Name Server Set Option
         (OPTION_REVERSE_NAME_SERVER_SET).

   - 4.:   Upon receiving the DHCP Zone Template Option
         (OPTION_DNS_ZONE_TEMPLATE), the CPE performs an AXFR DNS query
         for the Zone Template FQDN.  The exchange is secured according
         to the security protocols defined in the Security field of the
         DHCP option.  Once the CPE has retrieved the DNS Zone Template,
         the CPE can build the DNS Homenet Zone and the DNS Homenet
         Reverse Zone.  Eventually the CPE signs these zones.

   - 5.:   Once the DNS(SEC) Homenet Reverse Zone has been set, the CPE
         uploads the zone to the Reverse Public Authoritative Name
         Server Set. The DHCP Reverse Public Authoritative Name Server
         Set Option (OPTION_REVERSE_NAME_SERVER_SET) provides the
         Reverse Public Authoritative Name Server Set FQDN as well as
         the upload method, and the security protocol to secure the
         upload.

   - 6.:   Once the DNS(SEC) Homenet Zone has been set, the CPE uploads
         the zone to the Public Authoritative Name Server Set. The DHCP
         Public Authoritative Name Server Set Option
         (OPTION_NAME_SERVER_SET) provides the Public Authoritative Name
         Server Set FQDN as well as the upload method and the security
         protocol to secure the upload.

























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      +----------------------+
      |     DHCP Server      |
      +----------------------+
            ^   ^         ^
            |   |         |2.
          1.|   |3.       |
            v   v         |
           +------+       |    +--------------------------------+
           |      |  4.   +--->|  DNS Template Server           |
           |      |<---------->|                                |
           |      |       |    +--------------------------------+
           | CPE  |       |
           |      |       |    +--------------------------------+
           |      | 5./6. +--->|  Reverse Public Authoritative  |
           |      |<---------->|  Name Server Set               |
           |      |       |    +--------------------------------+
    -------|      |-------|--------------------------------------
           |      |       |    +--------------------------------+
           +------+       +--->|  Public Authoritative          |
                               |  Name Server Set               |
                               +--------------------------------+

                        Figure 1: Protocol Overview

   As described above, the CPE is likely to interact with various DNS
   content.  This section is focused on DNS Data the CPE is likely to
   update.  More specifically, the CPE is likely to update the:

   - DNS Homenet Zone Template:   may be updated by the CPE if the
         configuration of the zone may be changed.  This can include
         additional Public Authoritative Primary(ies), a different
         Registered Homenet Domain as the one initially proposed, or a
         redirection to another domain.

   - DNS Homenet Reverse Zone:   may be updated every time a new device
         is connected or dis-connected.

   - DNS Homenet Zone:   may be updated every time a new device is
         connected, dis-connected.

   In fact, the CPE must be able to perform these updates in a secure
   manner.  There are multiple ways to secure a DNS transaction and this
   document considers two mechanisms to update a DNS Data (nsupdate and
   primary/secondary synchronization).  Which security mechanism to use
   to secure a DNS transaction depends on the expected security
   (authentication of the authoritative server, mutual authentication,
   confidentiality...).  The expected security may also depends on the
   kind of transaction performed by the CPE.  Section 4.2 describes the



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   different security mechanisms considered in the document as well as
   their respective goals.  Which mechanism to use to update the DNS
   Data depends on the kind of update.  Frequency of the update, size of
   the DNS Data to update may be some useful criteria.  Section 4.3
   positions the nsupdate and primary/secondary synchronization
   mechanisms.

4.2.  Mechanisms Securing DNS Transactions

   Multiple protocols like IPsec [RFC4301] or TLS / DTLS [RFC5246] /
   [RFC6347] may be used to secure DNS transactions between the CPE and
   the DNS servers.  This document restricts the scope of security
   protocols to those that have been designed specifically for DNS.
   This includes DNSSEC [RFC4033], [RFC4034], [RFC4035] that
   authenticates and provides integrity protection of DNS data, TSIG
   [RFC2845], [RFC2930] that use a shared secret to secure a transaction
   between two end points and SIG(0) [RFC2931] authenticates the DNS
   packet exchanged.

   The key issue with TSIG is that a shared secret must be negotiated
   between the CPE and the server.  On the other hand, TSIG performs
   symmetric cryptography which is light in comparison with asymmetric
   cryptography used by SIG(0).  As a result, over large zone transfer,
   TSIG may be preferred to SIG(0).

   This document does not provides means to distribute shared secret for
   example using a specific DHCP Option.  The only assumption made is
   that the CPE generates or is assigned a public key.

   As a result, when the document specifies the transaction is secured
   with TSIG, it means that either the CPE and the DNS Server have been
   manually configured with a shared secret, or the shared secret has
   been negotiated using TKEY [RFC2930], and the TKEY exchanged are
   secured with SIG(0).

   Exchange with the DNS Template Server to retrieve the DNS Homenet
   Zone Template may be protected by SIG(0), TSIG or DNSSEC.  When
   DNSSEC is used, it means the DNS Template Server only provides
   integrity protection, and does not necessarily prevents someone else
   to query the DNS Homenet Zone Template.  In addition, DNSSEC is only
   a way to protect the AXFR queries transaction, in other words, DNSSEC
   cannot be used to secure updates.  If DNSSEC is used to provide
   integrity protection for the AXFR response, the CPE should proceed to
   the DNSSEC signature checks.  If signature check fails, it MUST
   reject the response.  If the signature check succeeds, the CPE
   removes all DNSSEC related RRsets (DNSKEY, RRSIG, NSEC* ...) before
   building the DNS Homenet Zone.  In fact, these DNSSEC related fields




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   are associated to the DNS Homenet Zone Template and not the DNS
   Homenet Zone.

   Any update exchange should use SIG(0) or TSIG to authenticate the
   exchange.

4.3.  Primary / Secondary Synchronization versus DNS Update

   As updates only concern DNS zones, this document only considers DNS
   update mechanisms such as DNS update [RFC2136]  [RFC3007] or a
   primary / secondary synchronization.

   The DNS Homenet Zone Template can only be updated with DNS update.
   The reason is that the DNS Homenet Zone Template contains static
   configuration data that is not expected to evolve over time.

   The DNS Homenet Reverse Zone and the DNS Homenet Zone can be updated
   either with DNS update or using a primary / secondary
   synchronization.  As these zones may be large, with frequent updates,
   we recommend to use the primary / secondary architecture as described
   in [I-D.ietf-homenet-front-end-naming-delegation].  The primary /
   secondary mechanism is preferred as it better scales and avoids DoS
   attacks: First the primary notifies the secondary the zone must be
   updated, and leaves the secondary to proceed to the update when
   possible.  Then, the NOTIFY message sent by the primary is a small
   packet that is less likely to load the secondary.  At last, the AXFR
   query performed by the secondary is a small packet sent over TCP
   (section 4.2 [RFC5936]) which makes unlikely the secondary to perform
   reflection attacks with a forged NOTIFY.  On the other hand, DNS
   updates can use UDP, packets require more processing then a NOTIFY,
   and they do not provide the server the opportunity to post-pone the
   update.

5.  CPE Configuration

5.1.  CPE Primary / Secondary Synchronization Configurations

   The primary / secondary architecture is described in
   [I-D.ietf-homenet-front-end-naming-delegation].  The CPE is
   configured as a primary whereas the DNS Server is configured as a
   secondary.  The DNS Server represents the Public Authoritative Name
   Server Set or the Reverse Public Authoritative Name Server Set.

   When the CPE is plugged its IP address may be unknown to the
   secondary.  The section details how the CPE or primary communicate
   the necessary information to set up the secondary.





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   In order to set the primary / secondary configuration, both primary
   and secondaries must agree on 1) the zone to be synchronized, 2) the
   IP address and ports used by both primary and secondary.

5.1.1.  CPE / Public Authoritative Name Server Set

   The CPE knows the zone to be synchronized by reading the Registered
   Homenet Domain in the DNS Homenet Zone Template provided by the DHCP
   Zone Template Option (OPTION_DNS_ZONE_TEMPLATE).  The IP address of
   the secondary is provided by the DHCP Public Authoritative Name
   Server Set Option (OPTION_NAME_SERVER_SET).

   The Public Authoritative Name Server Set has been configured with the
   Registered Homenet Domain and the Public Key that identifies the CPE.
   The only thing missing is the IP address of the CPE.  This IP address
   is provided by the CPE by sending a NOTIFY [RFC1996].

   When the CPE has built its DNS Homenet Zone, it sends a NOTIFY
   message to the Public Authoritative Name Server Sets.  Upon receiving
   the NOTIFY message, the secondary reads the Registered Homenet Domain
   and checks the NOTIFY is sent by the authorized primary.  This can be
   done using the shared secret (TSIG) or the public key (SIG(0)).  Once
   the NOTIFY has been authenticated, the Public Authoritative Name
   Server Sets might consider the source IP address of the NOTIFY query
   to configure the primaries attributes.

5.1.2.  CPE / Reverse Public Authoritative Name Server Set

   The CPE knows the zone to be synchronized by looking at its assigned
   prefix.  The IP address of the secondary is provided by the DHCP
   Reverse Public Authoritative Name Server Set Option
   (OPTION_REVERSE_NAME_SERVER_SET).

   Configuration of the secondary is performed as illustrated in
   Section 5.1.1.

5.2.  CPE DNS Data Handling and Update Policies

5.2.1.  DNS Homenet Zone Template

   The DNS Homenet Zone Template contains at least the related fields of
   the Public Authoritative Primary(ies) as well as the Homenet
   Registered Domain, that is SOA, and NS fields.  This template might
   be generated automatically by the owner of the DHCP Server.  For
   example, an ISP might provide a default Homenet Registered Domain as
   well as default Public Authoritative Primary(ies).  This default
   settings should provide the CPE the necessary pieces of information
   to set the homenet naming architecture.



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   If the DNS Homenet Zone Template is not subject to modifications or
   updates, the owner of the template might only use DNSSEC to enable
   integrity check.

   The DNS Homenet Zone Template might be subject to modification by the
   CPE.  The advantage of using the standard DNS zone format is that
   standard DNS update mechanism can be used to perform updates.  These
   updates might be accepted or rejected by the owner of the DNS Homenet
   Zone Template.  Policies that defines what is accepted or rejected is
   out of scope of this document.  However, in this document we assume
   the Registered Homenet Domain is used as an index by the Public
   Authoritative Name Server Set, and SIG(0), TSIG are used to
   authenticate the CPE.  As a result, the Registered Homenet Domain
   should not be modified unless the Public Authoritative Name Server
   Set can handle with it.

5.2.2.  DNS (Reverse) Homenet Zone

   The DNS Homenet Zone might be generated from the DNS Homenet Zone
   Template.  How the DNS Homenet Zone is generated is out of scope of
   this document.  In some cases, the DNS Homenet Zone might be the
   exact copy of the DNS Homenet Zone Template.  In other cases, it
   might be generated from the DNS Homenet Zone Template with additional
   RRsets.  In some other cases, the DNS Homenet Zone might be generated
   without considering the DNS Homenet Zone Template, but only
   considering specific configuration rules.

   In the current document the CPE only sets a single zone that is
   associated with one single Homenet Registered Domain.  The domain
   might be assigned by the owner of the DNS Homenet Zone Template.
   This constrain does not prevent the CPE to use multiple domain names.
   How additional domains are considered is out of scope of this
   document.  One way to handle these additional zones is to configure
   static redirections to the DNS Homenet Zone using CNAME [RFC2181],
   [RFC1034], DNAME [RFC6672] or CNAME+DNAME
   [I-D.sury-dnsext-cname-dname].

6.  Payload Description

   This section details the payload of the DHCP Options.  A few DHCP
   Options are used to advertise a server the CPE may be expect to
   interact with.  Interaction may require to define how the update is
   expected to be performed as well as how the communication is secured.
   Security and Update are shared by multiple DHCP Options and are
   described in separate sections.  Section 6.1 describes the security
   field, Section 6.2 describes the update fields, the remaining
   sections Section 6.3, Section 6.4, Section 6.5, Section 6.6 describe
   the DHCP Options.



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6.1.  Security Field

   The Security Field of the DHCP Option is represented in Figure 2.  It
   indicates the security mechanism supported by the DNS Server.  One of
   these mechanism MUST be chosen by the CPE in order to perform a
   transaction with the DNS server.  See Section 4.2 for more details.

    0                   1
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Security           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         Figure 2: Security Field

   - DNS (Bit 0):   indicates, when set to 1, that DNS without any
         security extension is supported.

   - DNSSEC (Bit 1):   indicates, when set to 1, that DNSSEC provides
         integrity protection.  This can only be used for read
         operations like retrieving the DNS Homenet Zone Template.

   - SIG(0) (Bit 2):   indicates, when set to 1, that transaction
         protected by SIG(0) are supported.

   - TSIG (Bit 3):   indicates, when set to 1, that transaction using
         TSIG is supported.  Note that if a shared secret has not been
         previously negotiated between the two party, it should be
         negotiated using TKEY.  The TKEY exchanges MUST be protected
         with SIG(0) even though SIG(0) is not supported.

   - Remaining Bits (Bit 4-15):   MUST be set to 0 by the DHCP Server
         and ignored by the DHCP Client.

   A Security field with all bits set to zero indicates the operation is
   not permitted.  The Security field may be set to zero when updates
   operations are not permitted for the DNS Homenet Template.  In any
   other case this is an error.

6.2.  Update Field

   The Update Field of the DHCP Option is represented in Figure 3.  It
   indicates the update mechanism supported by the DNS server.  See
   Section 4.3 for more details.







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    0
    0 1 2 3 4 5 6 7
   +-+-+-+-+-+-+-+-+
   |    Update     |
   +-+-+-+-+-+-+-+-+

                          Figure 3: Update Field

   - Primary / Secondary (Bit 0):   indicates, when set to 1, that DNS
         Server supports data synchronization using a Primary /
         Secondary mechanism.

   - DNS Update (Bit 1):   indicates, when set to 1, that DNS Server
         supports data synchronization using DNS Updates.

   - Remaining Bits (Bit 2-7):   MUST be set to 0 by the DHCP Server and
         ignored by the DHCP Client.

6.3.  DHCP Public Key Option

   The DHCP Public Key Option (OPTION_PUBLIC_KEY) indicates the Public
   Key that is used to authenticate the CPE.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       OPTION_PUBLIC_KEY       |          option-len           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   /                      Public Key Data                          /
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 4: DHCP Public Key Option

   - OPTION_PUBLIC_KEY (variable):  the option code for the DHCP Public
         Key Option.

   - option-len (16 bits):  length in octets of the option-data field as
         described in [RFC3315].

   - Public Key Data:  contains the Public Key. The format is the DNSKEY
         RDATA format as defined in [RFC4034].








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6.4.  DHCP Zone Template Option

   The DHCP Zone Template Option (OPTION_DNS_ZONE_TEMPLATE) Option
   indicates the CPE how to retrieve the DNS Homenet Zone Template.  It
   provides a FQDN the CPE SHOULD query with a DNS query of type AXFR.
   The option also specifies which security protocols are available on
   the authoritative server.  DNS Homenet Zone Template update, if
   permitted MUST use the DNS Update mechanism.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    OPTION_DNS_ZONE_TEMPLATE   |          option-len           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Security  (axfr)        |            Security           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   /                    Zone Template FQDN                         /
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 5: DHCP Zone Template Option

   - OPTION_DNS_ZONE_TEMPLATE (variable):  the option code for the DHCP
         Zone Template Option.

   - option-len (16 bits):  length in octets of the option-data field as
         described in [RFC3315].

   - Security (axfr) (16 bits):  defines which security protocols are
         supported by the DNS server.  This field concerns the AXFR and
         consultation queries, not the update queries.  See Section 6.1
         for more details.

   - Security (16 bits):  defines which security protocols are supported
         by the DNS server.  This field concerns the update.  See
         Section 6.1 for more details.

   - Zone Template FQDN FQDN (variable):  the FQDN of the DNS server
         hosting the DNS Homenet Zone Template.

6.5.  DHCP Public Authoritative Name Server Set Option

   The DHCP Public Authoritative Name Server Set Option
   (OPTION_NAME_SERVER_SET) provides information so the CPE can upload
   the DNS Homenet Zone to the Public Authoritative Name Server Set.
   Finally, the option provides the security mechanisms that are




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   available to perform the upload.  The upload is performed via a DNS
   primary / secondary architecture or DNS updates.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    OPTION_NAME_SERVER_SET     |          option-len           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Security           |    Update   |     Server      /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /     Port        |                                             |
   +-+-+-+-+-+-+-+-+-+                                             |
   |                                                               |
   /           Public Authoritative Name Server Set FQDN           /
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 6: DHCP Public Authoritative Name Server Set Option

   - OPTION_NAME_SERVER_SET (16 bits):  the option code for the DHCP
         Public Authoritative Name Server Set Option.

   - option-len (16 bits):  length in octets of the option-data field as
         described in [RFC3315].

   - Security (16 bits):  defines which security protocols are supported
         by the DNS server.  See Section 6.1 for more details.

   - Update (8 bits):  defines which update mechanisms are supported by
         the DNS server.  See Section 4.3 for more details.

   - Server Port (16 bits):  defines the port the Public Authoritative
         Name Server Set is listening.

   - Public Authoritative Name Server Set FQDN (variable):  the FQDN of
         the Public Authoritative Name Server Set.

6.6.  DHCP Reverse Public Authoritative Name Server Set Option

   The DHCP Reverse Public Authoritative Name Server Set Option
   (OPTION_REVERSE_NAME_SERVER_SET) provides information so the CPE can
   upload the DNS Homenet Zone to the Public Authoritative Name Server
   Set. The option provides the security mechanisms that are available
   to perform the upload.  The upload is performed via a DNS primary /
   secondary architecture or DNS updates.






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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | OPTION_REVERSE_NAME_SERVER_SET|          option-len           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Security           |    Update   |     Server      /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /     Port        |                                             |
   +-+-+-+-+-+-+-+-+-+                                             |
   |                                                               |
   /      Reverse Public Authoritative Name Server Set FQDN        /
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Figure 7: DHCP Reverse Public Authoritative Name Server Set Option

   - OPTION_REVERSE_NAME_SERVER_SET (16 bits):  the option code for the
         DHCP Reverse Public Authoritative Name Server Set Option.

   - option-len (16 bits):  length in octets of the option-data field as
         described in [RFC3315].

   - Security (16 bits):  defines which security protocols are supported
         by the DNS server.  See Section 6.1 for more details.

   - Update (8 bits):  defines which update mechanisms are supported by
         the DNS server.  See Section 4.3 for more details.

   - Server Port (16 bits):  defines the port the Public Authoritative
         Name Server Set is listening.

   - Reverse Public Authoritative Name Server Set FQDN (variable):  The
         FQDN of the Reverse Public Authoritative Name Server Set.

7.  DHCP Behavior

7.1.  DHCPv6 Server Behavior

   The DHCP Server sends the DHCP Zone Template Option
   (OPTION_DNS_ZONE_TEMPLATE), DHCP Public Authoritative Name Server Set
   Option (OPTION_NAME_SERVER_SET), DHCP Reverse Public Authoritative
   Name Server Set Option (OPTION_REVERSE_NAME_SERVER_SET) upon request
   by the DHCP Client.

   The DHCP Server MAY receive a DHCP Public Key Option
   (OPTION_PUBLIC_KEY) from the CPE.  Upon receipt of this DHCP Option,
   the DHCP Sever is expect to communicate this credential to the
   available DNS Servers like the DNS Template Server, the Public



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   Authoritative Name Server Set and the Reverse Public Authoritative
   Name Server Set.

7.2.  DHCPv6 Client Behavior

   The DHCP Client MAY send a DHCP Public Key Option (OPTION_PUBLIC_KEY)
   to the DHCP Server.  This Public Key authenticates the CPE.

   The DHCP Client sends a DHCP Option Request Option (ORO) with the
   necessary DHCP options.

   A CPE SHOULD only send the an ORO request for DHCP Options it needs
   or for information that needs to be up-to-date.

   Upon receiving a DHCP option described in this document, the CPE
   SHOULD retrieve or update DNS zones using the associated security and
   update protocols.

7.3.  DHCPv6 Relay Behavior

   DHCP Relay behavior are not modified by this document.

8.  IANA Considerations

   The DHCP options detailed in this document is:

   - OPTION_DNS_ZONE_TEMPLATE:  TBD

   - OPTION_NAME_SERVER_SET:  TBD

   - OPTION_REVERSE_NAME_SERVER_SET:  TBD

   - OPTION_PUBLIC_KEY:  TBD

9.  Security Considerations

9.1.  DNSSEC is recommended to authenticate DNS hosted data

   It is recommended that the (Reverse) DNS Homenet Zone is signed with
   DNSSEC.  The zone may be signed by the CPE or by a third party.  We
   recommend the zone to be signed by the CPE, and that the signed zone
   is uploaded.

9.2.  Channel between the CPE and ISP DHCP Server MUST be secured

   The document considers that the channel between the CPE and the ISP
   DHCP Server is trusted.  More specifically, the CPE is authenticated
   and the exchanged messages are protected.  The current document does



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   not specify how to secure the channel.  [RFC3315] proposes a DHCP
   authentication and message exchange protection, [RFC4301], [RFC7296]
   propose to secure the channel at the IP layer.

   In fact, the channel MUST be secured because the CPE provides
   authentication credentials.  Unsecured channel may result in CPE
   impersonation attacks.

9.3.  CPEs are sensitive to DoS

   CPE have not been designed for handling heavy load.  The CPE are
   exposed on the Internet, and their IP address is publicly published
   on the Internet via the DNS.  This makes the Home Network sensitive
   to Deny of Service Attacks.  The resulting outsourcing architecture
   is described in [I-D.ietf-homenet-front-end-naming-delegation].  This
   document shows how the outsourcing architecture can be automatically
   set.

10.  Acknowledgment

   We would like to thank Tomasz Mrugalski, Marcin Siodelski and Bernie
   Volz for their comments on the design of the DHCP Options.  We would
   also like to thank Mark Andrews, Andrew Sullivan and Lorenzo Colliti
   for their remarks on the architecture design.  The designed solution
   has been largely been inspired by Mark Andrews's document
   [I-D.andrews-dnsop-pd-reverse] as well as discussions with Mark.

11.  References

11.1.  Normative References

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, November 1987.

   [RFC1996]  Vixie, P., "A Mechanism for Prompt Notification of Zone
              Changes (DNS NOTIFY)", RFC 1996, August 1996.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2136]  Vixie, P., Thomson, S., Rekhter, Y., and J. Bound,
              "Dynamic Updates in the Domain Name System (DNS UPDATE)",
              RFC 2136, April 1997.

   [RFC2181]  Elz, R. and R. Bush, "Clarifications to the DNS
              Specification", RFC 2181, July 1997.





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   [RFC2845]  Vixie, P., Gudmundsson, O., Eastlake, D., and B.
              Wellington, "Secret Key Transaction Authentication for DNS
              (TSIG)", RFC 2845, May 2000.

   [RFC2930]  Eastlake, D., "Secret Key Establishment for DNS (TKEY
              RR)", RFC 2930, September 2000.

   [RFC2931]  Eastlake, D., "DNS Request and Transaction Signatures (
              SIG(0)s)", RFC 2931, September 2000.

   [RFC3007]  Wellington, B., "Secure Domain Name System (DNS) Dynamic
              Update", RFC 3007, November 2000.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements", RFC
              4033, March 2005.

   [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Resource Records for the DNS Security Extensions",
              RFC 4034, March 2005.

   [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Protocol Modifications for the DNS Security
              Extensions", RFC 4035, March 2005.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [RFC5936]  Lewis, E. and A. Hoenes, "DNS Zone Transfer Protocol
              (AXFR)", RFC 5936, June 2010.

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, January 2012.

   [RFC6672]  Rose, S. and W. Wijngaards, "DNAME Redirection in the
              DNS", RFC 6672, June 2012.

   [RFC7296]  Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
              Kivinen, "Internet Key Exchange Protocol Version 2
              (IKEv2)", STD 79, RFC 7296, October 2014.




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11.2.  Informational References

   [I-D.andrews-dnsop-pd-reverse]
              Andrews, M., "Automated Delegation of IP6.ARPA reverse
              zones with Prefix Delegation", draft-andrews-dnsop-pd-
              reverse-02 (work in progress), November 2013.

   [I-D.ietf-homenet-front-end-naming-delegation]
              Migault, D., Cloetens, W., Griffiths, C., and R. Weber,
              "Outsourcing Home Network Authoritative Naming Service",
              draft-ietf-homenet-front-end-naming-delegation-02 (work in
              progress), May 2015.

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

Appendix A.  Scenarios and impact on the End User

   This section details various scenarios and discuss their impact on
   the end user.

A.1.  Base Scenario

   The base scenario is the one described in Section 4.  It is typically
   the one of an ISP that manages the DHCP Server, and all DNS servers.

   The end user subscribes to the ISP (foo), and at subscription time
   registers for example.foo as its Registered Homenet Domain
   example.foo.  Since the ISP knows the Registered Homenet Domain and
   the Public Authoritative Primary(ies) the ISP is able to build the
   DNS Homenet Zone Template.

   The ISP manages the DNS Template Server, so it is able to load the
   DNS Homenet Zone Template on the DNS Template Server.

   When the CPE is plugged (at least the first time), it provides its
   Public Key to the DHCP Server.  In this scenario, the DHCP Server and
   the DNS Servers are managed by the ISP so the DHCP Server can provide
   authentication credentials of the CPE to enable secure authenticated
   transaction between the CPE and these DNS servers.  More
   specifically, credentials are provided to:

   -     Public Authoritative Name Server Set

   -     Reverse Public Authoritative Name Server Set

   -     DNS Template Server



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   The CPE can update the zone using DNS update or a primary / secondary
   configuration in a secure way.

   The main advantage of this scenario is that the naming architecture
   is configured automatically and transparently for the end user.

   The drawbacks are that the end user uses a Registered Homenet Domain
   managed by the ISP and that it relies on the ISP naming
   infrastructure.

A.2.  Third Party Registered Homenet Domain

   This section considers the case when the end user wants its home
   network to use example.com as a Registered Homenet Domain instead of
   example.foo that has been assigned by the ISP.  We also suppose that
   example.com is not managed by the ISP.

   This can also be achieved without any configuration.  When the end
   user buys the domain name example.com, it may request to redirect the
   name example.com to example.foo using static redirection with CNAME
   [RFC2181], [RFC1034], DNAME [RFC6672] or CNAME+DNAME
   [I-D.sury-dnsext-cname-dname].

   This configuration is performed once when the domain name example.com
   is registered.  The only information the end user needs to know is
   the domain name assigned by the ISP.  Once this configuration is done
   no additional configuration is needed anymore.  More specifically,
   the CPE may be changed, the zone can be updated as in Appendix A.1
   without any additional configuration from the end user.

   The main advantage of this scenario is that the end user benefits
   from the Zero Configuration of the Base Scenario Appendix A.1.  Then,
   the end user is able to register for its home network an unlimited
   number of domain names provided by an unlimited number of different
   third party providers.

   The drawback of this scenario may be that the end user still rely on
   the ISP naming infrastructure.  Note that the only case this may be
   inconvenient is when the DNS Servers provided by the ISPs results in
   high latency.

A.3.  Third Party DNS Infrastructure

   This scenario considers that the end user uses example.com as a
   Registered Homenet Domain, and does not want to rely on the
   authoritative servers provided by the ISP.





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   In this section we limit the outsourcing to the Public Authoritative
   Name Server Set and Public Authoritative Primary(ies) to a third
   party.  All other DNS Servers DNS Template Server, Reverse Public
   Authoritative Primary(ies) and Reverse Public Authoritative Name
   Server Set remain managed by the ISP.  The reason we consider that
   Reverse Public Authoritative Primary(ies) and Reverse Public
   Authoritative Name Server Set remains managed by the ISP are that the
   prefix is managed by the ISP, so outsourcing these resources requires
   some redirection agreement with the ISP.  More specifically the ISP
   will need to configure the redirection on one of its Reverse DNS
   Servers.  That said, outsourcing these resources is similar as
   outsourcing Public Authoritative Name Server Set and Public
   Authoritative Primary(ies) to a third party.  Similarly, the DNS
   Template Server can be easily outsourced as detailed in this section

   Outsourcing Public Authoritative Name Server Set and Public
   Authoritative Primary(ies) requires:

   - 1)  Updating the DNS Homenet Zone Template: this can be easily done
         as detailed in Section 4.3 as the DNS Template Server is still
         managed by the ISP.  Such modification can be performed once by
         any CPE.  Once this modification has been performed, the CPE
         can be changed, the Public Key of the CPE may be changed, this
         does not need to be done another time.  One can imagine a GUI
         on the CPE asking the end user to fill the field with
         Registered Homenet Domain, optionally Public Authoritative
         Primary(ies), with a button "Configure DNS Homenet Zone
         Template".

   - 2)  Updating the DHCP Server Information.  In fact the Reverse
         Public Authoritative Name Server Set returned by the ISP is
         modified.  One can imagine a GUI interface that enables the end
         user to modify its profile parameters.  Again, this
         configuration update is done once-for-ever.

   - 3)  Upload the authentication credential of the CPE, that is the
         Public Key of the CPE, to the third party.  Unless we use
         specific mechanisms, like communication between the DHCP Server
         and the third party, or a specific token that is plugged into
         the CPE, this operation is likely to be performed every time
         the CPE is changed, and every time the Public Key generated by
         the CPE is changed.

   The main advantage of this scenario is that the DNS infrastructure is
   completely outsourced to the third party.  Most likely the Public Key
   that authenticate the CPE need to be configured for every CPE.
   Configuration is expected to be CPE live-long.




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A.4.  Multiple ISPs

   This scenario considers a CPE connected to multiple ISPs.

   Firstly, suppose the CPE has been configured with the based scenarios
   exposed in Appendix A.1.  The CPE has multiple interfaces, one for
   each ISP, and each of these interface is configured using DHCP.  The
   CPE sends to each ISP its DHCP Public Key Option as well as a request
   for a DHCP Zone Template Option, a DHCP Public Authoritative Name
   Server Set Option and a DHCP Reverse Public Authoritative Name Server
   Set Option.  Each ISP provides the requested DHCP options, with
   different values.  Note that this scenario assumes, the home network
   has a different Registered Homenet Domain for each ISP as it is
   managed by the ISP.  On the other hand, the CPE Public Key may be
   shared between the CPE and the multiple ISPs.  The CPE builds the
   associate DNS(SEC) Homenet Zone, and proceeds to the various settings
   as described in Appendix A.1.

   The protocol and DHCP Options described in this document are fully
   compatible with a CPE connected to multiple ISPs with multiple
   Registered Homenet Domains.  However, the CPE should be able to
   handle different Registered Homenet Domains.  This is an
   implementation issue which is outside the scope of the current
   document.  More specifically, multiple Registered Homenet Domains
   leads to multiple DNS(SEC) Homenet Zones.  A basic implementation may
   erase the DNS(SEC) Homenet Zone that exists when it receives DHCP
   Options, and rebuild everything from scratch.  This will work for an
   initial configuration but comes with a few drawbacks.  First, updates
   to the DNS(SEC) Homenet Zone may only push to one of the multiple
   Registered Homenet Domain, the latest Registered Homenet Domain that
   has been set, and this is most likely expected to be almost randomly
   chosen as it may depend on the latency on each ISP network at the
   boot time.  As a results, this leads to unsynchronized Registered
   Homenet Domains.  Secondly, if the CPE handles in some ways
   resolution, only the latest Registered Homenet Domain set may be able
   to provide naming resolution in case of network disruption.

   Secondly, suppose the CPE is connected to multiple ISP with a single
   Registered Homenet Domain.  In this case, the one party is chosen to
   host the Registered Homenet Domain.  This entity may be one of the
   ISP or a third party.  Note that having multiple ISPs can be
   motivated for bandwidth aggregation, or connectivity fail-over.  In
   the case of connectivity fail-over, the fail-over concerns the access
   network and a failure of the access network may not impact the core
   network where the Public Authoritative Name Server Set and Public
   Authoritative Primaries are hosted.  In that sense, choosing one of
   the ISP even in a scenario of multiple ISPs may make sense.  However,
   for sake of simplicity, this scenario assumes that a third party has



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   be chosen to host the Registered Homenet Domain.  The DNS settings
   for each ISP is described in Appendix A.2 and Appendix A.3.  With the
   configuration described in Appendix A.2, the CPE is expect to be able
   to handle multiple Homenet Registered Domain, as the third party
   redirect to one of the ISPs Servers.  With the configuration
   described in Appendix A.3, DNS zone are hosted and maintained by the
   third party.  A single DNS(SEC) Homenet Zone is built and maintained
   by the CPE.  This latter configuration is likely to match most CPE
   implementations.

   The protocol and DHCP Options described in this document are fully
   compatible with a CPE connected to multiple ISPs.  To configure or
   not and how to configure the CPE depends on the CPE facilities.
   Appendix A.1 and Appendix A.2 require the CPE to handle multiple
   Registered Homenet Domain, whereas Appendix A.3 does not have such
   requirement.

Appendix B.  Document Change Log

   [RFC Editor: This section is to be removed before publication]

   -05: changing Master to Primary, Slave to Secondary

   -04: Working Version Major modifications are:

   - Re-structuring the draft:  description and comparison of update and
         security mechanisms have been intergrated into the Overview
         section. a Configuration section has been created to describe
         both configuration and corresponding behavior of the CPE.

   - Adding Ports parameters:  Server Set can configure a port.  The
         Port Server parameter have been added in the DHCP Option
         payloads because middle boxes may not be configured to let port
         53 packets and it may also be useful to split servers among
         different ports, assigning each end user a different port.

   - Multiple ISP scenario:  In order to address comments, the multiple
         ISPs scenario has been described to explicitly show that the
         protocol and DHCP Options do not prevent a CPE connected to
         multiple independent ISPs.

   -03: Working Version Major modifications are:

   - Redesigning options/scope:  according to feed backs received from
         the IETF89 presentation in the dhc WG.






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   - Redesigning architecture:  according to feed backs received from
         the IETF89 presentation in the homenet WG, discussion with Mark
         and Lorenzo.

   -02: Working Version Major modifications are:

   - Redesigning options/scope:  As suggested by Bernie Volz

   -01: Working Version Major modifications are:

   - Remove the DNS Zone file construction:  As suggested by Bernie Volz

   - DHCPv6 Client behavior:  Following options guide lines

   - DHCPv6 Server behavior:  Following options guide lines

   -00: version published in the homenet WG.  Major modifications are:

   - Reformatting of DHCP Options:  Following options guide lines

   - DHCPv6 Client behavior:  Following options guide lines

   - DHCPv6 Server behavior:  Following options guide lines

   -00: First version published in dhc WG.

Authors' Addresses

   Daniel Migault
   Ericsson
   8400 boulevard Decarie
   Montreal, QC H4P 2N2
   Canada

   Email: daniel.migault@ericsson.com


   Wouter Cloetens
   SoftAtHome
   vaartdijk 3 701
   3018 Wijgmaal
   Belgium

   Email: wouter.cloetens@softathome.com







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   Chris Griffiths
   Dyn
   150 Dow Street
   Manchester, NH  03101
   US

   Email: cgriffiths@dyn.com
   URI:   http://dyn.com


   Ralf Weber
   Nominum
   2000 Seaport Blvd #400
   Redwood City, CA  94063
   US

   Email: ralf.weber@nominum.com
   URI:   http://www.nominum.com

































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