draft-ietf-homenet-front-end-naming-delegation-04.txt   draft-ietf-homenet-front-end-naming-delegation-05.txt 
HOMENET D. Migault (Ed) HOMENET D. Migault (Ed)
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track R. Weber Intended status: Standards Track R. Weber
Expires: March 26, 2016 Nominum Expires: February 16, 2017 Nominum
R. Hunter R. Hunter
Globis Consulting BV Globis Consulting BV
C. Griffiths C. Griffiths
W. Cloetens W. Cloetens
SoftAtHome SoftAtHome
September 23, 2015 August 15, 2016
Outsourcing Home Network Authoritative Naming Service Outsourcing Home Network Authoritative Naming Service
draft-ietf-homenet-front-end-naming-delegation-04.txt draft-ietf-homenet-front-end-naming-delegation-05.txt
Abstract Abstract
RFC7368 'IPv6 Home Networking Architecture Principles' section 3.7 Designation of services and devices of a home network is not user
describes architecture principles related to naming and service friendly, and mechanisms should enable a user to designate services
discovery in residential home networks. and devices inside a home network using names.
Customer Edge Routers and other Customer Premises Equipment (CPEs)
are designed to provide IP connectivity to home networks. Most CPEs
assign IP addresses to the nodes of the home network which makes them
good candidates for hosting the naming service. IPv6 provides global
connectivity, and nodes from the home network will be reachable from
the global Internet. As a result, the naming service is expected to
be exposed on the Internet.
However, CPEs have not been designed to host such a naming service
exposed on the Internet. Running a naming service visible on the
Internet may expose the CPEs to resource exhaustion and other
attacks, which could make the home network unreachable, and most
probably would also affect the internal communications of the home
network.
In addition, regular end users may not understand, or possess the In order to enable internal communications while the home network
necessary skills to be able to perform, DNSSEC management and experiments Internet connectivity shortage, the naming service should
configuration. Misconfiguration may also result in naming service be hosted on a device inside the home network. On the other hand,
disruption, thus these end users may prefer to rely on third party home networks devices have not been designed to handle heavy loads.
name service providers. As a result, hosting the naming service on such home network device,
visible on the Internet exposes this device to resource exhaustion
and other attacks, which could make the home network unreachable, and
most probably would also affect the internal communications of the
home network.
This document describes a homenet naming architecture, where the CPEs As result, home networks may prefer not serving the naming service
manage the DNS zones associated with its own home network, and for the Internet, but instead prefer outsourcing it to a third party.
outsource elements of the naming service (possibly including DNSSEC This document describes a mechanisms that enables the Home Network
management) to a third party running on the Internet. Authority (HNA) to outsource the naming service to the Outsourcing
Infrastructure.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 26, 2016. This Internet-Draft will expire on February 16, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Scope of the Document . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Architecture Description . . . . . . . . . . . . . . . . . . 6
4. Architecture Description . . . . . . . . . . . . . . . . . . 7 4.1. Architecture Overview . . . . . . . . . . . . . . . . . . 6
4.1. Architecture Overview . . . . . . . . . . . . . . . . . . 7 4.2. Example: Homenet Zone . . . . . . . . . . . . . . . . . . 8
4.2. Example: Homenet Zone . . . . . . . . . . . . . . . . . . 9 4.3. Example: HNA necessary parameters for outsourcing . . . . 10
4.3. Example: CPE necessary parameters for outsourcing . . . . 11 5. Synchronization between HNA and the Synchronization Server . 11
5. Synchronization between CPE and the Synchronization Server . 12 5.1. Synchronization with a Hidden Primary . . . . . . . . . . 11
5.1. Synchronization with a Hidden Primary . . . . . . . . . . 12 5.2. Securing Synchronization . . . . . . . . . . . . . . . . 12
5.2. Securing Synchronization . . . . . . . . . . . . . . . . 13 5.3. HNA Security Policies . . . . . . . . . . . . . . . . . . 14
5.3. CPE Security Policies . . . . . . . . . . . . . . . . . . 15 6. DNSSEC compliant Homenet Architecture . . . . . . . . . . . . 14
6. DNSSEC compliant Homenet Architecture . . . . . . . . . . . . 15 6.1. Zone Signing . . . . . . . . . . . . . . . . . . . . . . 14
6.1. Zone Signing . . . . . . . . . . . . . . . . . . . . . . 15 6.2. Secure Delegation . . . . . . . . . . . . . . . . . . . . 16
6.2. Secure Delegation . . . . . . . . . . . . . . . . . . . . 17 7. Handling Different Views . . . . . . . . . . . . . . . . . . 17
7. Handling Different Views . . . . . . . . . . . . . . . . . . 18 7.1. Misleading Reasons for Local Scope DNS Zone . . . . . . . 17
7.1. Misleading Reasons for Local Scope DNS Zone . . . . . . . 18 7.2. Consequences . . . . . . . . . . . . . . . . . . . . . . 18
7.2. Consequences . . . . . . . . . . . . . . . . . . . . . . 19 7.3. Guidance and Recommendations . . . . . . . . . . . . . . 18
7.3. Guidance and Recommendations . . . . . . . . . . . . . . 19 8. Homenet Reverse Zone . . . . . . . . . . . . . . . . . . . . 19
8. Homenet Reverse Zone . . . . . . . . . . . . . . . . . . . . 20 9. Renumbering . . . . . . . . . . . . . . . . . . . . . . . . . 19
9. Renumbering . . . . . . . . . . . . . . . . . . . . . . . . . 20 9.1. Hidden Primary . . . . . . . . . . . . . . . . . . . . . 20
9.1. Hidden Primary . . . . . . . . . . . . . . . . . . . . . 21 9.2. Synchronization Server . . . . . . . . . . . . . . . . . 21
9.2. Synchronization Server . . . . . . . . . . . . . . . . . 22 10. Privacy Considerations . . . . . . . . . . . . . . . . . . . 22
10. Privacy Considerations . . . . . . . . . . . . . . . . . . . 23 11. Security Considerations . . . . . . . . . . . . . . . . . . . 22
11. Security Considerations . . . . . . . . . . . . . . . . . . . 23 11.1. Names are less secure than IP addresses . . . . . . . . 22
11.1. Names are less secure than IP addresses . . . . . . . . 23 11.2. Names are less volatile than IP addresses . . . . . . . 23
11.2. Names are less volatile than IP addresses . . . . . . . 24 11.3. DNS Reflection Attacks . . . . . . . . . . . . . . . . . 23
11.3. DNS Reflection Attacks . . . . . . . . . . . . . . . . . 24 11.3.1. Reflection Attack involving the Hidden Primary . . . 23
11.3.1. Reflection Attack involving the Hidden Primary . . . 24
11.3.2. Reflection Attacks involving the Synchronization 11.3.2. Reflection Attacks involving the Synchronization
Server . . . . . . . . . . . . . . . . . . . . . . . 26 Server . . . . . . . . . . . . . . . . . . . . . . . 25
11.3.3. Reflection Attacks involving the Public 11.3.3. Reflection Attacks involving the Public
Authoritative Servers . . . . . . . . . . . . . . . 27 Authoritative Servers . . . . . . . . . . . . . . . 26
11.4. Flooding Attack . . . . . . . . . . . . . . . . . . . . 27 11.4. Flooding Attack . . . . . . . . . . . . . . . . . . . . 26
11.5. Replay Attack . . . . . . . . . . . . . . . . . . . . . 27 11.5. Replay Attack . . . . . . . . . . . . . . . . . . . . . 26
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27
13. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 28 13. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 27
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 28 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 27
14.1. Normative References . . . . . . . . . . . . . . . . . . 28 14.1. Normative References . . . . . . . . . . . . . . . . . . 27
14.2. Informational References . . . . . . . . . . . . . . . . 31 14.2. Informational References . . . . . . . . . . . . . . . . 30
Appendix A. Document Change Log . . . . . . . . . . . . . . . . 32 Appendix A. Document Change Log . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
1. Requirements notation 1. Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Introduction 2. Introduction
IPv6 provides global end to end IP reachability. End users prefer to IPv6 provides global end to end IP reachability. End users prefer to
use names instead of long and complex IPv6 addresses when accessing use names instead of long and complex IPv6 addresses when accessing
services hosted in the home network. services hosted in the home network.
Customer Edge Routers and other Customer Premises Equipment (CPEs) Customer Edge Routers and other Customer Premises Equipment (CPEs)
are already providing IPv6 connectivity to the home network, and are already providing IPv6 connectivity to the home network, and
generally provide IPv6 addresses or prefixes to the nodes of the home generally provide IPv6 addresses or prefixes to the nodes of the home
network. This makes CPEs good candidates to manage the binding network. In addition, [RFC7368] recommends that home networks be
between names and IP addresses of nodes. In addition, [RFC7368] resilient to connectivity disruption from the ISP. This could be
recommends that home networks be resilient to connectivity disruption achieved by a dedicated device inside the home network that builds,
from the ISP. This could be achieved by a dedicated device inside serves or manage the Homenet Zone, thus providing bindings between
the home network that builds the Homenet Zone, thus providing names and IP addresses.
bindings between names and IP addresses. All this makes the CPE the
natural candidate for populating the Homenet zone.
CPEs are usually low powered devices designed for the home network, CPEs are of course good candidates to manage the binding between
but not for terminating heavy traffic. As a result, hosting an names and IP addresses of nodes. However, this could also be
authoritative DNS service on the Internet may expose the home network performed by another device in the home network that is not a CPE.
to resource exhaustion and other attacks. This may isolate the home In addition, a given home network may have multiple nodes that may
network from the Internet and also impact the services hosted by the implement this functionality. Since management of the Homenet Zone
CPEs, thus affecting overall home network communication. involves DNS specific mechanisms that cannot be distributed (primary
server), when multiple nodes can potentially manage the Homenet Zone,
a single node needs to be selected. This selected node is designated
as the Homenet Naming Authority (HNA).
CPEs, Homenet Naming Authority, as well as home network devices are
usually low powered devices not designed not for terminating heavy
traffic. As a result, hosting an authoritative DNS service on the
Internet may expose the home network to resource exhaustion and other
attacks. This may isolate the home network from the Internet and
also impact the services hosted by the such an home network device,
thus affecting overall home network communication.
In order to avoid resource exhaustion and other attacks, this In order to avoid resource exhaustion and other attacks, this
document describes an architecture that outsources the authoritative document describes an architecture that outsources the authoritative
naming service of the home network. More specifically, the Homenet naming service of the home network. More specifically, the Homenet
Zone built by the CPE is outsourced to an Outsourcing Infrastructure. Naming Authority builds the Homenet Zone and outsources it to an
The Outsourcing Infrastructure publishes the corresponding Public Outsourcing Infrastructure. The Outsourcing Infrastructure in in
Homenet Zone on the Internet. Section 4.1 describes the charge of publishing the corresponding Public Homenet Zone on the
architecture. In order to keep the Public Homenet Zone up-to-date Internet.
Section 4.1 provides an architecture description that describes the
relation between the Homenet Naming Authority and the Outsourcing
Architecture. In order to keep the Public Homenet Zone up-to-date
Section 5 describes how the Homenet Zone and the Public Homenet Zone Section 5 describes how the Homenet Zone and the Public Homenet Zone
can be synchronized. The proposed architecture aims at deploying can be synchronized. The proposed architecture aims at deploying
DNSSEC, and the Public Homenet Zone is expected to be signed with a DNSSEC, and the Public Homenet Zone is expected to be signed with a
secure delegation. The zone signing and secure delegation may be secure delegation. The zone signing and secure delegation may be
performed either by the CPE or by the Outsourcing Infrastructure. performed either by the Homenet Naming Authority or by the
Section 6 discusses these two alternatives. Section 7 discusses the Outsourcing Infrastructure. Section 6 discusses these two
consequences of publishing multiple representations of the same zone alternatives. Section 7 discusses the consequences of publishing
also commonly designated as views. This section provides guidance to multiple representations of the same zone also commonly designated as
limit the risks associated with multiple views. Section 8 discusses views. This section provides guidance to limit the risks associated
management of the reverse zone. Section 9 discusses how renumbering with multiple views. Section 8 discusses management of the reverse
should be handled. Finally, Section 10 and Section 11 respectively zone. Section 9 discusses how renumbering should be handled.
discuss privacy and security considerations when outsourcing the Finally, Section 10 and Section 11 respectively discuss privacy and
Homenet Zone. security considerations when outsourcing the Homenet Zone.
2.1. Scope of the Document
The scope of the document is to describe an architecture that
outsources the authoritative naming service of the home network and
more specifically the interactions between the home network and the
Outsourcing Infrastructure. Considerations or descriptions on inner
communications or organization of the home network are provided for
completeness and for clarifying the interface between the home
network and the Outsourcing Infrastructure
For sake of simplicity, this document designates by "CPE" that
connects the home network with the Outsourcing Infrastructure - and
so performs most of the operations for outsourcing the home network
naming architecture. On the other hand, CPE are usually associated
to home router. These two functions - e.g routing and naming - are
not correlated and could be split in multiple devices. More
specifically, this document does not consider the home network has a
single CPE nor a single ISP.
In fact this document considers the CPE as a set of functionalities
that can be collocated on a single device or split between multiple
devices. The split of these functions between different devices as
well as their potential associated communications is considered as
implementation dependent and out of scope of the architecture. The
only limitation this architecture considers is that the Hidden
Primary be located in a single place as long as the distributed
Primary architecture has not been defined. As a result, if there are
multiple candidates for hosting the Hidden Primary, the home network
should select a single device.
3. Terminology 3. Terminology
- Customer Premises Equipment: (CPE) is a router providing - Customer Premises Equipment: (CPE) is a router providing
connectivity to the home network. It might be configured and connectivity to the home network.
managed by the end user. In this document, the CPE might also
host services such as DHCPv6. This device might be provided by - Homenet Naming Authority: (HNA) is a home network node
the ISP. A home network may have multiple CPE, and each of responsible to manage the Homenet Zone. This includes building
them may be connected to an Internet Service Provider. In this the Homenet Zone, as well as managing the distribution of that
document, the CPE represents the set of functions involved in Homenet Zone through the Outsourcing Infrastructure.
the naming architecture. These functions may be collocated on
a single device, or distributed between multiple devices. How
these functions communicate is out of the scope of this
document and is left for implementation. See Section 2.1 for
more details.
- Registered Homenet Domain: is the Domain Name associated to the - Registered Homenet Domain: is the Domain Name associated to the
home network. home network.
- Homenet Zone: is the DNS zone associated with the home network. - Homenet Zone: is the DNS zone associated with the home network.
It is designated by its Registered Homenet Domain. This zone It is designated by its Registered Homenet Domain. This zone
is built by the CPE and contains the bindings between names and is built by the HNA and contains the bindings between names and
IP addresses of the nodes in the home network. The CPE IP addresses of the nodes in the home network. The HNA
synchronizes the Homenet Zone with the Synchronization Server synchronizes the Homenet Zone with the Synchronization Server
via a hidden primary / secondary architecture. The Outsourcing via a hidden primary / secondary architecture. The Outsourcing
Infrastructure may process the Homenet Zone - for example Infrastructure may process the Homenet Zone - for example
providing DNSSEC signing - to generate the Public Homenet Zone. providing DNSSEC signing - to generate the Public Homenet Zone.
This Public Homenet Zone is then transmitted to the Public This Public Homenet Zone is then transmitted to the Public
Authoritative Server(s) that publish it on the Internet. Authoritative Server(s) that publish it on the Internet.
- Public Homenet Zone: is the public version of the Homenet Zone. - Public Homenet Zone: is the public version of the Homenet Zone.
It is expected to be signed with DNSSEC. It is hosted by the It is expected to be signed with DNSSEC. It is hosted by the
Public Authoritative Server(s), which are authoritative for Public Authoritative Server(s), which are authoritative for
skipping to change at page 6, line 17 skipping to change at page 5, line 31
Homenet Zone is not signed. Homenet Zone is not signed.
- Outsourcing Infrastructure: is the combination of the - Outsourcing Infrastructure: is the combination of the
Synchronization Server and the Public Authoritative Server(s). Synchronization Server and the Public Authoritative Server(s).
- Public Authoritative Servers: are the authoritative name servers - Public Authoritative Servers: are the authoritative name servers
hosting the Public Homenet Zone. Name resolution requests for hosting the Public Homenet Zone. Name resolution requests for
the Homenet Domain are sent to these servers. For resiliency the Homenet Domain are sent to these servers. For resiliency
the Public Homenet Zone SHOULD be hosted on multiple servers. the Public Homenet Zone SHOULD be hosted on multiple servers.
- Synchronization Server: is the server with which the CPE - Synchronization Server: is the server with which the HNA
synchronizes the Homenet Zone. The Synchronization Server is synchronizes the Homenet Zone. The Synchronization Server is
configured as a secondary and the CPE acts as primary. There configured as a secondary and the HNA acts as primary. There
MAY be multiple Synchronization Servers, but the text assumes a MAY be multiple Synchronization Servers, but the text assumes a
single server. In addition, the text assumes the single server. In addition, the text assumes the
Synchronization Server is a separate entity. This is not a Synchronization Server is a separate entity. This is not a
requirement, and when the CPE signs the zone, the requirement, and when the HNA signs the zone, the
synchronization function might also be operated by the Public synchronization function might also be operated by the Public
Authoritative Servers. Authoritative Servers.
- Homenet Reverse Zone: The reverse zone file associated with the - Homenet Reverse Zone: The reverse zone file associated with the
Homenet Zone. Homenet Zone.
- Reverse Public Authoritative Servers: are the authoritative name - Reverse Public Authoritative Servers: are the authoritative name
server(s) hosting the Public Homenet Reverse Zone. Queries for server(s) hosting the Public Homenet Reverse Zone. Queries for
reverse resolution of the Homenet Domain are sent to this reverse resolution of the Homenet Domain are sent to this
server. Similarly to Public Authoritative Servers, for server. Similarly to Public Authoritative Servers, for
resiliency, the Homenet Reverse Zone SHOULD be hosted on resiliency, the Homenet Reverse Zone SHOULD be hosted on
multiple servers. multiple servers.
- Reverse Synchronization Server: is the server with which the CPE - Reverse Synchronization Server: is the server with which the HNA
synchronizes the Homenet Reverse Zone. It is configured as a synchronizes the Homenet Reverse Zone. It is configured as a
secondary and the CPE acts as primary. There MAY be multiple secondary and the HNA acts as primary. There MAY be multiple
Reverse Synchronization Servers, but the text assumes a single Reverse Synchronization Servers, but the text assumes a single
server. In addition, the text assumes the Reverse server. In addition, the text assumes the Reverse
Synchronization Server is a separate entity. This is not a Synchronization Server is a separate entity. This is not a
requirement, and when the CPE signs the zone, the requirement, and when the HNA signs the zone, the
synchronization function might also be operated by the Reverse synchronization function might also be operated by the Reverse
Public Authoritative Servers. Public Authoritative Servers.
- Hidden Primary: designates the primary server of the CPE, that - Hidden Primary: designates the primary server of the HNA, that
synchronizes the Homenet Zone with the Synchronization Server. synchronizes the Homenet Zone with the Synchronization Server.
A primary / secondary architecture is used between the CPE and A primary / secondary architecture is used between the HNA and
the Synchronization Server. The hidden primary is not expected the Synchronization Server. The hidden primary is not expected
to serve end user queries for the Homenet Zone as a regular to serve end user queries for the Homenet Zone as a regular
primary server would. The hidden primary is only known to its primary server would. The hidden primary is only known to its
associated Synchronization Server. associated Synchronization Server.
4. Architecture Description 4. Architecture Description
This section describes the architecture for outsourcing the This section describes the architecture for outsourcing the
authoritative naming service from the CPE to the Outsourcing authoritative naming service from the HNA to the Outsourcing
Infrastructure. Section 4.1 describes the architecture, Section 4.2 Infrastructure. Section 4.1 describes the architecture, Section 4.2
and Section 4.3 illustrates this architecture and shows how the and Section 4.3 illustrates this architecture and shows how the
Homenet Zone should be built by the CPE. It also lists the necessary Homenet Zone should be built by the HNA. It also lists the necessary
parameters the CPE needs to be able to outsource the authoritative parameters the HNA needs to be able to outsource the authoritative
naming service. These two sections are informational and non- naming service. These two sections are informational and non-
normative. normative.
4.1. Architecture Overview 4.1. Architecture Overview
Figure 1 provides an overview of the architecture. Figure 1 provides an overview of the architecture.
The home network is designated by the Registered Homenet Domain Name The home network is designated by the Registered Homenet Domain Name
-- example.com in Figure 1. The CPE builds the Homenet Zone -- example.com in Figure 1. The HNA builds the Homenet Zone
associated with the home network. How the Homenet Zone is built is associated with the home network. How the Homenet Zone is built is
out of the scope of this document. The CPE may host or interact with out of the scope of this document. The HNA may host or interact with
multiple services to determine name-to-address mappings, such as a multiple services to determine name-to-address mappings, such as a
web GUI, DHCP [RFC6644] or mDNS [RFC6762]. These services may web GUI, DHCP [RFC6644] or mDNS [RFC6762]. These services may
coexist and may be used to populate the Homenet Zone. This document coexist and may be used to populate the Homenet Zone. This document
assumes the Homenet Zone has been populated with domain names that assumes the Homenet Zone has been populated with domain names that
are intended to be publicly published and that are publicly are intended to be publicly published and that are publicly
reachable. More specifically, names associated with services or reachable. More specifically, names associated with services or
devices that are not expected to be reachable from outside the home devices that are not expected to be reachable from outside the home
network or names bound to non-globally reachable IP addresses MUST network or names bound to non-globally reachable IP addresses MUST
NOT be part of the Homenet Zone. NOT be part of the Homenet Zone.
Once the Homenet Zone has been built, the CPE does not host an Once the Homenet Zone has been built, the HNA does not host an
authoritative naming service, but instead outsources it to the authoritative naming service, but instead outsources it to the
Outsourcing Infrastructure. The Outsourcing Infrastructure takes the Outsourcing Infrastructure. The Outsourcing Infrastructure takes the
Homenet Zone as an input and publishes the Public Homenet Zone. If Homenet Zone as an input and publishes the Public Homenet Zone. If
the CPE does not sign the Homenet Zone, the Outsourcing the HNA does not sign the Homenet Zone, the Outsourcing
Infrastructure may instead sign it on behalf of the CPE. Figure 1 Infrastructure may instead sign it on behalf of the HNA. Figure 1
provides a more detailed description of the Outsourcing provides a more detailed description of the Outsourcing
Infrastructure, but overall, it is expected that the CPE provides the Infrastructure, but overall, it is expected that the HNA provides the
Homenet Zone. Then the Public Homenet Zone is derived from the Homenet Zone. Then the Public Homenet Zone is derived from the
Homenet Zone and published on the Internet. Homenet Zone and published on the Internet.
As a result, DNS queries from the DNS resolvers on the Internet are As a result, DNS queries from the DNS resolvers on the Internet are
answered by the Outsourcing Infrastructure and do not reach the CPE. answered by the Outsourcing Infrastructure and do not reach the HNA.
Figure 1 illustrates the case of the resolution of node1.example.com. Figure 1 illustrates the case of the resolution of node1.example.com.
home network +-------------------+ Internet home network +-------------------+ Internet
| | | |
| CPE | | HNA |
| | +-----------------------+ | | +-----------------------+
+-------+ |+-----------------+| | Public Authoritative | +-------+ |+-----------------+| | Public Authoritative |
| | || Homenet Zone || | Server(s) | | | || Homenet Zone || | Server(s) |
| node1 | || || |+---------------------+| | node1 | || || |+---------------------+|
| | || || || Public Homenet Zone || | | || || || Public Homenet Zone ||
+-------+ || Homenet Domain ||=========|| || +-------+ || Homenet Domain ||=========|| ||
|| Name || ^ || (example.com) || || Name || ^ || (example.com) ||
node1.\ || (example.com) || | |+---------------------+| node1.\ || (example.com) || | |+---------------------+|
example.com |+-----------------+| | +-----------------------+ example.com |+-----------------+| | +-----------------------+
+-------------------+ | ^ | +-------------------+ | ^ |
skipping to change at page 8, line 34 skipping to change at page 7, line 49
| | | |
+-----------------------+ +-----------------------+
Figure 1: Homenet Naming Architecture Description Figure 1: Homenet Naming Architecture Description
The Outsourcing Infrastructure is described in Figure 2. The The Outsourcing Infrastructure is described in Figure 2. The
Synchronization Server receives the Homenet Zone as an input. The Synchronization Server receives the Homenet Zone as an input. The
received zone may be transformed to output the Public Homenet Zone. received zone may be transformed to output the Public Homenet Zone.
Various operations may be performed here, however this document only Various operations may be performed here, however this document only
considers zone signing as a potential operation. This should occur considers zone signing as a potential operation. This should occur
only when the CPE outsources this operation to the Synchronization only when the HNA outsources this operation to the Synchronization
Server. On the other hand, if the CPE signs the Homenet Zone itself, Server. On the other hand, if the HNA signs the Homenet Zone itself,
the zone would be collected by the Synchronization Server and the zone would be collected by the Synchronization Server and
directly transferred to the Public Authoritative Server(s). These directly transferred to the Public Authoritative Server(s). These
policies are discussed and detailed in Section 6 and Section 7. policies are discussed and detailed in Section 6 and Section 7.
Internet Internet
+------------------------------------------------------+ +------------------------------------------------------+
| Outsourcing Infrastructure | | Outsourcing Infrastructure |
+------------------------------------------------------+ +------------------------------------------------------+
skipping to change at page 9, line 25 skipping to change at page 8, line 27
| | | | | | | |
| +------------------+ | X |+--------------------+| | +------------------+ | X |+--------------------+|
| | Homenet Zone | | ^ || Public Homenet Zone|| | | Homenet Zone | | ^ || Public Homenet Zone||
=========>| | | | || || =========>| | | | || ||
^ | | | | | || || ^ | | | | | || ||
| | | (example.com) | | | || (example.com) || | | | (example.com) | | | || (example.com) ||
| | +------------------+ | | |+--------------------+| | | +------------------+ | | |+--------------------+|
| +----------------------+ | +----------------------+ | +----------------------+ | +----------------------+
| Homenet to Public Zone | Homenet to Public Zone
Synchronization transformation Synchronization transformation
from the CPE from the HNA
Figure 2: Outsourcing Infrastructure Description Figure 2: Outsourcing Infrastructure Description
4.2. Example: Homenet Zone 4.2. Example: Homenet Zone
This section is not normative and intends to illustrate how the CPE This section is not normative and intends to illustrate how the HNA
builds the Homenet Zone. builds the Homenet Zone.
As depicted in Figure 1 and Figure 2, the Public Homenet Zone is As depicted in Figure 1 and Figure 2, the Public Homenet Zone is
hosted on the Public Authoritative Server(s), whereas the Homenet hosted on the Public Authoritative Server(s), whereas the Homenet
Zone is hosted on the CPE. Motivations for keeping these two zones Zone is hosted on the HNA. Motivations for keeping these two zones
identical are detailed in Section 7, and this section considers that identical are detailed in Section 7, and this section considers that
the CPE builds the zone that will be effectively published on the the HNA builds the zone that will be effectively published on the
Public Authoritative Server(s). In other words "Homenet to Public Public Authoritative Server(s). In other words "Homenet to Public
Zone transformation" is the identity also commonly designated as "no Zone transformation" is the identity also commonly designated as "no
operation" (NOP). operation" (NOP).
In that case, the Homenet Zone should configure its Name Server RRset In that case, the Homenet Zone should configure its Name Server RRset
(NS) and Start of Authority (SOA) with the values associated with the (NS) and Start of Authority (SOA) with the values associated with the
Public Authoritative Server(s). This is illustrated in Figure 3. Public Authoritative Server(s). This is illustrated in Figure 3.
public.primary.example.net is the FQDN of the Public Authoritative public.primary.example.net is the FQDN of the Public Authoritative
Server(s), and IP1, IP2, IP3, IP4 are the associated IP addresses. Server(s), and IP1, IP2, IP3, IP4 are the associated IP addresses.
Then the CPE should add the additional new nodes that enter the home Then the HNA should add the additional new nodes that enter the home
network, remove those that should be removed, and sign the Homenet network, remove those that should be removed, and sign the Homenet
Zone. Zone.
$ORIGIN example.com $ORIGIN example.com
$TTL 1h $TTL 1h
@ IN SOA public.primary.example.net @ IN SOA public.primary.example.net
hostmaster.example.com. ( hostmaster.example.com. (
2013120710 ; serial number of this zone file 2013120710 ; serial number of this zone file
1d ; secondary refresh 1d ; secondary refresh
skipping to change at page 10, line 36 skipping to change at page 9, line 38
The SOA RRset is defined in [RFC1033], [RFC1035] and [RFC2308]. This The SOA RRset is defined in [RFC1033], [RFC1035] and [RFC2308]. This
SOA is specific, as it is used for the synchronization between the SOA is specific, as it is used for the synchronization between the
Hidden Primary and the Synchronization Server and published on the Hidden Primary and the Synchronization Server and published on the
DNS Public Authoritative Server(s).. DNS Public Authoritative Server(s)..
- MNAME: indicates the primary. In our case the zone is published - MNAME: indicates the primary. In our case the zone is published
on the Public Authoritative Server(s), and its name MUST be on the Public Authoritative Server(s), and its name MUST be
included. If multiple Public Authoritative Server(s) are included. If multiple Public Authoritative Server(s) are
involved, one of them MUST be chosen. More specifically, the involved, one of them MUST be chosen. More specifically, the
CPE MUST NOT include the name of the Hidden Primary. HNA MUST NOT include the name of the Hidden Primary.
- RNAME: indicates the email address to reach the administrator. - RNAME: indicates the email address to reach the administrator.
[RFC2142] recommends using hostmaster@domain and replacing the [RFC2142] recommends using hostmaster@domain and replacing the
'@' sign by '.'. '@' sign by '.'.
- REFRESH and RETRY: indicate respectively in seconds how often - REFRESH and RETRY: indicate respectively in seconds how often
secondaries need to check the primary, and the time between two secondaries need to check the primary, and the time between two
refresh when a refresh has failed. Default values indicated by refresh when a refresh has failed. Default values indicated by
[RFC1033] are 3600 (1 hour) for refresh and 600 (10 minutes) [RFC1033] are 3600 (1 hour) for refresh and 600 (10 minutes)
for retry. This value might be too long for highly dynamic for retry. This value might be too long for highly dynamic
content. However, the Public Authoritative Server(s) and the content. However, the Public Authoritative Server(s) and the
CPE are expected to implement NOTIFY [RFC1996]. So whilst HNA are expected to implement NOTIFY [RFC1996]. So whilst
shorter refresh timers might increase the bandwidth usage for shorter refresh timers might increase the bandwidth usage for
secondaries hosting large number of zones, it will have little secondaries hosting large number of zones, it will have little
practical impact on the elapsed time required to achieve practical impact on the elapsed time required to achieve
synchronization between the Outsourcing Infrastructure and the synchronization between the Outsourcing Infrastructure and the
Hidden Master. As a result, the default values are acceptable. Hidden Master. As a result, the default values are acceptable.
EXPIRE: is the upper limit data SHOULD be kept in absence of EXPIRE: is the upper limit data SHOULD be kept in absence of
refresh. The default value indicated by [RFC1033] is 3600000 refresh. The default value indicated by [RFC1033] is 3600000
(approx. 42 days). In home network architectures, the CPE (approx. 42 days). In home network architectures, the HNA
provides both the DNS synchronization and the access to the provides both the DNS synchronization and the access to the
home network. This device may be plugged and unplugged by the home network. This device may be plugged and unplugged by the
end user without notification, thus we recommend a long expiry end user without notification, thus we recommend a long expiry
timer. timer.
MINIMUM: indicates the minimum TTL. The default value indicated by MINIMUM: indicates the minimum TTL. The default value indicated by
[RFC1033] is 86400 (1 day). For home network, this value MAY [RFC1033] is 86400 (1 day). For home network, this value MAY
be reduced, and 3600 (1 hour) seems more appropriate. be reduced, and 3600 (1 hour) seems more appropriate.
4.3. Example: CPE necessary parameters for outsourcing 4.3. Example: HNA necessary parameters for outsourcing
This section specifies the various parameters required by the CPE to This section specifies the various parameters required by the HNA to
configure the naming architecture of this document. This section is configure the naming architecture of this document. This section is
informational, and is intended to clarify the information handled by informational, and is intended to clarify the information handled by
the CPE and the various settings to be done. the HNA and the various settings to be done.
Synchronization Server may be configured with the following Synchronization Server may be configured with the following
parameters. These parameters are necessary to establish a secure parameters. These parameters are necessary to establish a secure
channel between the CPE and the Synchronization Server as well as to channel between the HNA and the Synchronization Server as well as to
specify the DNS zone that is in the scope of the communication: specify the DNS zone that is in the scope of the communication:
- Synchronization Server: The associated FQDNs or IP addresses of - Synchronization Server: The associated FQDNs or IP addresses of
the Synchronization Server. IP addresses are optional and the the Synchronization Server. IP addresses are optional and the
FQDN is sufficient. To secure the binding name and IP FQDN is sufficient. To secure the binding name and IP
addresses, a DNSSEC exchange is required. Otherwise, the IP addresses, a DNSSEC exchange is required. Otherwise, the IP
addresses should be entered manually. addresses should be entered manually.
- Authentication Method: How the CPE authenticates itself to the - Authentication Method: How the HNA authenticates itself to the
Synchronization Server. This MAY depend on the implementation Synchronization Server. This MAY depend on the implementation
but this should cover at least IPsec, DTLS and TSIG but this should cover at least IPsec, DTLS and TSIG
- Authentication data: Associated Data. PSK only requires a single - Authentication data: Associated Data. PSK only requires a single
argument. If other authentication mechanisms based on argument. If other authentication mechanisms based on
certificates are used, then CPE private keys, certificates and certificates are used, then HNA private keys, certificates and
certification authority should be specified. certification authority should be specified.
- Public Authoritative Server(s): The FQDN or IP addresses of the - Public Authoritative Server(s): The FQDN or IP addresses of the
Public Authoritative Server(s). It MAY correspond to the data Public Authoritative Server(s). It MAY correspond to the data
that will be set in the NS RRsets and SOA of the Homenet Zone. that will be set in the NS RRsets and SOA of the Homenet Zone.
IP addresses are optional and the FQDN is sufficient. To IP addresses are optional and the FQDN is sufficient. To
secure the binding between name and IP addresses, a DNSSEC secure the binding between name and IP addresses, a DNSSEC
exchange is required. Otherwise, the IP addresses should be exchange is required. Otherwise, the IP addresses should be
entered manually. entered manually.
- Registered Homenet Domain: The domain name used to establish the - Registered Homenet Domain: The domain name used to establish the
secure channel. This name is used by the Synchronization secure channel. This name is used by the Synchronization
Server and the CPE for the primary / secondary configuration as Server and the HNA for the primary / secondary configuration as
well as to index the NOTIFY queries of the CPE when the CPE has well as to index the NOTIFY queries of the HNA when the HNA has
been renumbered. been renumbered.
Setting the Homenet Zone requires the following information. Setting the Homenet Zone requires the following information.
- Registered Homenet Domain: The Domain Name of the zone. Multiple - Registered Homenet Domain: The Domain Name of the zone. Multiple
Registered Homenet Domains may be provided. This will generate Registered Homenet Domains may be provided. This will generate
the creation of multiple Public Homenet Zones. the creation of multiple Public Homenet Zones.
- Public Authoritative Server(s): The Public Authoritative - Public Authoritative Server(s): The Public Authoritative
Server(s) associated with the Registered Homenet Domain. Server(s) associated with the Registered Homenet Domain.
Multiple Public Authoritative Server(s) may be provided. Multiple Public Authoritative Server(s) may be provided.
5. Synchronization between CPE and the Synchronization Server 5. Synchronization between HNA and the Synchronization Server
The Homenet Reverse Zone and the Homenet Zone MAY be updated either The Homenet Reverse Zone and the Homenet Zone MAY be updated either
with DNS UPDATE [RFC2136] or using a primary / secondary with DNS UPDATE [RFC2136] or using a primary / secondary
synchronization. The primary / secondary mechanism is preferred as synchronization. The primary / secondary mechanism is preferred as
it scales better and avoids DoS attacks: First the primary notifies it scales better and avoids DoS attacks: First the primary notifies
the secondary that the zone must be updated and leaves the secondary the secondary that the zone must be updated and leaves the secondary
to proceed with the update when possible. Then, a NOTIFY message is to proceed with the update when possible. Then, a NOTIFY message is
sent by the primary, which is a small packet that is less likely to sent by the primary, which is a small packet that is less likely to
load the secondary. Finally, the AXFR query performed by the load the secondary. Finally, the AXFR query performed by the
secondary is a small packet sent over TCP (section 4.2 [RFC5936]), secondary is a small packet sent over TCP (section 4.2 [RFC5936]),
skipping to change at page 12, line 47 skipping to change at page 11, line 48
perform asynchronous updates. perform asynchronous updates.
This document RECOMMENDS use of a primary / secondary mechanism This document RECOMMENDS use of a primary / secondary mechanism
instead of the use of DNS UPDATE. This section details the primary / instead of the use of DNS UPDATE. This section details the primary /
secondary mechanism. secondary mechanism.
5.1. Synchronization with a Hidden Primary 5.1. Synchronization with a Hidden Primary
Uploading and dynamically updating the zone file on the Uploading and dynamically updating the zone file on the
Synchronization Server can be seen as zone provisioning between the Synchronization Server can be seen as zone provisioning between the
CPE (Hidden Primary) and the Synchronization Server (Secondary HNA (Hidden Primary) and the Synchronization Server (Secondary
Server). This can be handled either in band or out of band. Server). This can be handled either in band or out of band.
Note that there is no standard way to distribute a DNS primary Note that there is no standard way to distribute a DNS primary
between multiple devices. As a result, if multiple CPEs are between multiple devices. As a result, if multiple devices are
candidate for hosting the Hidden Primary, some specific mechanisms candidate for hosting the Hidden Primary, some specific mechanisms
should be designed so the home network only selects a single CPE for should be designed so the home network only selects a single HNA for
the Hidden Primary. Selection mechanisms based on HNCP are good the Hidden Primary. Selection mechanisms based on HNCP [RFC7788] are
candidates [XXX]. good candidates.
The Synchronization Server is configured as a secondary for the The Synchronization Server is configured as a secondary for the
Homenet Domain Name. This secondary configuration has been Homenet Domain Name. This secondary configuration has been
previously agreed between the end user and the provider of the previously agreed between the end user and the provider of the
Synchronization Server. In order to set the primary / secondary Synchronization Server. In order to set the primary / secondary
architecture, the CPE acts as a Hidden Primary Server, which is a architecture, the HNA acts as a Hidden Primary Server, which is a
regular authoritative DNS Server listening on the WAN interface. regular authoritative DNS Server listening on the WAN interface.
The Hidden Primary Server SHOULD accept SOA [RFC1033], AXFR The Hidden Primary Server SHOULD accept SOA [RFC1033], AXFR
[RFC1034], and IXFR [RFC1995] queries from its configured secondary [RFC1034], and IXFR [RFC1995] queries from its configured secondary
DNS server(s). The Hidden Primary Server SHOULD send NOTIFY messages DNS server(s). The Hidden Primary Server SHOULD send NOTIFY messages
[RFC1996] in order to update Public DNS server zones as updates [RFC1996] in order to update Public DNS server zones as updates
occur. Because, the Homenet Zones are likely to be small, the CPE occur. Because, the Homenet Zones are likely to be small, the HNA
MUST implement AXFR and SHOULD implement IXFR. MUST implement AXFR and SHOULD implement IXFR.
Hidden Primary Server differs from a regular authoritative server for Hidden Primary Server differs from a regular authoritative server for
the home network by: the home network by:
- Interface Binding: the Hidden Primary Server listens on the WAN - Interface Binding: the Hidden Primary Server listens on the WAN
Interface, whereas a regular authoritative server for the home Interface, whereas a regular authoritative server for the home
network would listen on the home network interface. network would listen on the home network interface.
- Limited exchanges: the purpose of the Hidden Primary Server is to - Limited exchanges: the purpose of the Hidden Primary Server is to
synchronize with the Synchronization Server, not to serve any synchronize with the Synchronization Server, not to serve any
zones to end users. As a result, exchanges are performed with zones to end users. As a result, exchanges are performed with
specific nodes (the Synchronization Server). Further, exchange specific nodes (the Synchronization Server). Further, exchange
types are limited. The only legitimate exchanges are: NOTIFY types are limited. The only legitimate exchanges are: NOTIFY
initiated by the Hidden Primary and IXFR or AXFR exchanges initiated by the Hidden Primary and IXFR or AXFR exchanges
initiated by the Synchronization Server. On the other hand, initiated by the Synchronization Server. On the other hand,
regular authoritative servers would respond to any hosts, and regular authoritative servers would respond to any hosts, and
any DNS query would be processed. The CPE SHOULD filter IXFR/ any DNS query would be processed. The HNA SHOULD filter IXFR/
AXFR traffic and drop traffic not initiated by the AXFR traffic and drop traffic not initiated by the
Synchronization Server. The CPE MUST listen for DNS on TCP and Synchronization Server. The HNA MUST listen for DNS on TCP and
UDP and MUST at least allow SOA lookups of the Homenet Zone. UDP and MUST at least allow SOA lookups of the Homenet Zone.
5.2. Securing Synchronization 5.2. Securing Synchronization
Exchange between the Synchronization Server and the CPE MUST be Exchange between the Synchronization Server and the HNA MUST be
secured, at least for integrity protection and for authentication. secured, at least for integrity protection and for authentication.
TSIG [RFC2845] or SIG(0) [RFC2931] MAY be used to secure the DNS TSIG [RFC2845] or SIG(0) [RFC2931] MAY be used to secure the DNS
communications between the CPE and the Synchronization Server. TSIG communications between the HNA and the Synchronization Server. TSIG
uses a symmetric key which can be managed by TKEY [RFC2930]. uses a symmetric key which can be managed by TKEY [RFC2930].
Management of the key involved in SIG(0) is performed through zone Management of the key involved in SIG(0) is performed through zone
updates. How keys are rolled over with SIG(0) is out-of-scope of updates. How keys are rolled over with SIG(0) is out-of-scope of
this document. The advantage of these mechanisms is that they are this document. The advantage of these mechanisms is that they are
only associated with the DNS application. Not relying on shared only associated with the DNS application. Not relying on shared
libraries eases testing and integration. On the other hand, using libraries eases testing and integration. On the other hand, using
TSIG, TKEY or SIG(0) requires these mechanisms to be implemented on TSIG, TKEY or SIG(0) requires these mechanisms to be implemented on
the CPE, which adds code and complexity. Another disadvantage is the HNA, which adds code and complexity. Another disadvantage is
that TKEY does not provide authentication mechanisms. that TKEY does not provide authentication mechanisms.
Protocols like TLS [RFC5246] / DTLS [RFC6347] MAY be used to secure Protocols like TLS [RFC5246] / DTLS [RFC6347] MAY be used to secure
the transactions between the Synchronization Server and the CPE. The the transactions between the Synchronization Server and the HNA. The
advantage of TLS/DTLS is that this technology is widely deployed, and advantage of TLS/DTLS is that this technology is widely deployed, and
most of the devices already embed TLS/DTLS libraries, possibly also most of the devices already embed TLS/DTLS libraries, possibly also
taking advantage of hardware acceleration. Further, TLS/DTLS taking advantage of hardware acceleration. Further, TLS/DTLS
provides authentication facilities and can use certificates to provides authentication facilities and can use certificates to
authenticate the Synchronization Server and the CPE. On the other authenticate the Synchronization Server and the HNA. On the other
hand, using TLS/DTLS requires implementing DNS exchanges over TLS/ hand, using TLS/DTLS requires implementing DNS exchanges over TLS/
DTLS, as well as a new service port. This document therefore does DTLS, as well as a new service port. This document therefore does
NOT RECOMMEND this option. NOT RECOMMEND this option.
IPsec [RFC4301] IKEv2 [RFC7296] MAY also be used to secure IPsec [RFC4301] IKEv2 [RFC7296] MAY also be used to secure
transactions between the CPE and the Synchronization Server. transactions between the HNA and the Synchronization Server.
Similarly to TLS/DTLS, most CPEs already embed an IPsec stack, and Similarly to TLS/DTLS, most HNAs already embed an IPsec stack, and
IKEv2 supports multiple authentication mechanisms via the EAP IKEv2 supports multiple authentication mechanisms via the EAP
framework. In addition, IPsec can be used to protect DNS exchanges framework. In addition, IPsec can be used to protect DNS exchanges
between the CPE and the Synchronization Server without any between the HNA and the Synchronization Server without any
modifications of the DNS server or client. DNS integration over modifications of the DNS server or client. DNS integration over
IPsec only requires an additional security policy in the Security IPsec only requires an additional security policy in the Security
Policy Database (SPD). One disadvantage of IPsec is that NATs and Policy Database (SPD). One disadvantage of IPsec is that NATs and
firewall traversal may be problematic. However, in our case, the CPE firewall traversal may be problematic. However, in our case, the HNA
is connected to the Internet, and IPsec communication between the CPE is connected to the Internet, and IPsec communication between the HNA
and the Synchronization Server should not be impacted by middle and the Synchronization Server should not be impacted by middle
boxes. boxes.
How the PSK can be used by any of the TSIG, TLS/DTLS or IPsec How the PSK can be used by any of the TSIG, TLS/DTLS or IPsec
protocols: Authentication based on certificates implies a mutual protocols: Authentication based on certificates implies a mutual
authentication and thus requires the CPE to manage a private key, a authentication and thus requires the HNA to manage a private key, a
public key, or certificates, as well as Certificate Authorities. public key, or certificates, as well as Certificate Authorities.
This adds complexity to the configuration especially on the CPE side. This adds complexity to the configuration especially on the HNA side.
For this reason, we RECOMMEND that the CPE MAY use PSK or certificate For this reason, we RECOMMEND that the HNA MAY use PSK or certificate
base authentication, and that the Synchronization Server MUST support base authentication, and that the Synchronization Server MUST support
PSK and certificate based authentication. PSK and certificate based authentication.
Note also that authentication of message exchanges between the CPE Note also that authentication of message exchanges between the HNA
and the Synchronization Server SHOULD NOT use the external IP address and the Synchronization Server SHOULD NOT use the external IP address
of the CPE to index the appropriate keys. As detailed in Section 9, of the HNA to index the appropriate keys. As detailed in Section 9,
the IP addresses of the Synchronization Server and the Hidden Primary the IP addresses of the Synchronization Server and the Hidden Primary
are subject to change, for example while the network is being are subject to change, for example while the network is being
renumbered. This means that the necessary keys to authenticate renumbered. This means that the necessary keys to authenticate
transaction SHOULD NOT be indexed using the IP address, and SHOULD be transaction SHOULD NOT be indexed using the IP address, and SHOULD be
resilient to IP address changes. resilient to IP address changes.
5.3. CPE Security Policies 5.3. HNA Security Policies
This section details security policies related to the Hidden Primary This section details security policies related to the Hidden Primary
/ Secondary synchronization. / Secondary synchronization.
The Hidden Primary, as described in this document SHOULD drop any The Hidden Primary, as described in this document SHOULD drop any
queries from the home network. This could be implemented via port queries from the home network. This could be implemented via port
binding and/or firewall rules. The precise mechanism deployed is out binding and/or firewall rules. The precise mechanism deployed is out
of scope of this document. of scope of this document.
The Hidden Primary SHOULD drop any DNS queries arriving on the WAN The Hidden Primary SHOULD drop any DNS queries arriving on the WAN
skipping to change at page 15, line 38 skipping to change at page 14, line 40
6. DNSSEC compliant Homenet Architecture 6. DNSSEC compliant Homenet Architecture
[RFC7368] in Section 3.7.3 recommends DNSSEC to be deployed on both [RFC7368] in Section 3.7.3 recommends DNSSEC to be deployed on both
the authoritative server and the resolver. The resolver side is out the authoritative server and the resolver. The resolver side is out
of scope of this document, and only the authoritative part of the of scope of this document, and only the authoritative part of the
server is considered. server is considered.
Deploying DNSSEC requires signing the zone and configuring a secure Deploying DNSSEC requires signing the zone and configuring a secure
delegation. As described in Section 4.1, signing can be performed delegation. As described in Section 4.1, signing can be performed
either by the CPE or by the Outsourcing Infrastructure. Section 6.1 either by the HNA or by the Outsourcing Infrastructure. Section 6.1
details the implications of these two alternatives. Similarly, the details the implications of these two alternatives. Similarly, the
secure delegation can be performed by the CPE or by the Outsourcing secure delegation can be performed by the HNA or by the Outsourcing
Infrastructure. Section 6.2 discusses these two alternatives. Infrastructure. Section 6.2 discusses these two alternatives.
6.1. Zone Signing 6.1. Zone Signing
This section discusses the pros and cons when zone signing is This section discusses the pros and cons when zone signing is
performed by the CPE or by the Outsourcing Infrastructure. It is performed by the HNA or by the Outsourcing Infrastructure. It is
RECOMMENDED that the CPE signs the zone unless there is a strong RECOMMENDED that the HNA signs the zone unless there is a strong
argument against this, such as a CPE that is not capable of signing argument against this, such as a HNA that is not capable of signing
the zone. In that case zone signing MAY be performed by the the zone. In that case zone signing MAY be performed by the
Outsourcing Infrastructure on behalf of the CPE. Outsourcing Infrastructure on behalf of the HNA.
Reasons for signing the zone by the CPE are: Reasons for signing the zone by the HNA are:
- 1: Keeping the Homenet Zone and the Public Homenet Zone equal to - 1: Keeping the Homenet Zone and the Public Homenet Zone equal to
securely optimize DNS resolution. As the Public Zone is signed securely optimize DNS resolution. As the Public Zone is signed
with DNSSEC, RRsets are authenticated, and thus DNS responses with DNSSEC, RRsets are authenticated, and thus DNS responses
can be validated even though they are not provided by the can be validated even though they are not provided by the
authoritative server. This provides the CPE the ability to authoritative server. This provides the HNA the ability to
respond on behalf of the Public Authoritative Server(s). This respond on behalf of the Public Authoritative Server(s). This
could be useful for example if, in the future, the CPE could be useful for example if, in the future, the HNA
announces to the home network that the CPE can act as a local announces to the home network that the HNA can act as a local
authoritative primary or equivalent for the Homenet Zone. authoritative primary or equivalent for the Homenet Zone.
Currently the CPE is not expected to receive authoritative DNS Currently the HNA is not expected to receive authoritative DNS
queries, as its IP address is not mentioned in the Public queries, as its IP address is not mentioned in the Public
Homenet Zone. On the other hand most CPEs host a resolving Homenet Zone. On the other hand most HNAs host a resolving
function, and could be configured to perform a local lookup to function, and could be configured to perform a local lookup to
the Homenet Zone instead of initiating a DNS exchange with the the Homenet Zone instead of initiating a DNS exchange with the
Public Authoritative Server(s). Note that outsourcing the zone Public Authoritative Server(s). Note that outsourcing the zone
signing operation means that all DNSSEC queries SHOULD be signing operation means that all DNSSEC queries SHOULD be
cached to perform a local lookup, otherwise a resolution with cached to perform a local lookup, otherwise a resolution with
the Public Authoritative Server(s) would be performed. the Public Authoritative Server(s) would be performed.
- 2: Keeping the Homenet Zone and the Public Homenet Zone equal to - 2: Keeping the Homenet Zone and the Public Homenet Zone equal to
securely address the connectivity disruption independence securely address the connectivity disruption independence
detailed in [RFC7368] section 4.4.1 and 3.7.5. As local detailed in [RFC7368] section 4.4.1 and 3.7.5. As local
skipping to change at page 16, line 44 skipping to change at page 15, line 46
to DNSSEC responses provided by the Public Authoritative to DNSSEC responses provided by the Public Authoritative
Server(s). Server(s).
- 3: Keeping the Homenet Zone and the Public Homenet Zone equal to - 3: Keeping the Homenet Zone and the Public Homenet Zone equal to
guarantee coherence between DNS responses. Using a unique zone guarantee coherence between DNS responses. Using a unique zone
is one way to guarantee uniqueness of the responses among is one way to guarantee uniqueness of the responses among
servers and places. Issues generated by different views are servers and places. Issues generated by different views are
discussed in more details in Section 7. discussed in more details in Section 7.
- 2: Privacy and Integrity of the DNSSEC Homenet Zone are better - 2: Privacy and Integrity of the DNSSEC Homenet Zone are better
guaranteed. When the Zone is signed by the CPE, it makes guaranteed. When the Zone is signed by the HNA, it makes
modification of the DNS data -- for example for flow modification of the DNS data -- for example for flow
redirection -- impossible. As a result, signing the Homenet redirection -- impossible. As a result, signing the Homenet
Zone by the CPE provides better protection for end user Zone by the HNA provides better protection for end user
privacy. privacy.
Reasons for signing the zone by the Outsourcing Infrastructure are: Reasons for signing the zone by the Outsourcing Infrastructure are:
- 1: The CPE may not be capable of signing the zone, most likely - 1: The HNA may not be capable of signing the zone, most likely
because its firmware does not support this function. However because its firmware does not support this function. However
this reason is expected to become less and less valid over this reason is expected to become less and less valid over
time. time.
- 2: Outsourcing DNSSEC management operations. Management - 2: Outsourcing DNSSEC management operations. Management
operations involve key roll-over, which can be performed operations involve key roll-over, which can be performed
automatically by the CPE and transparently for the end user. automatically by the HNA and transparently for the end user.
Avoiding DNSSEC management is mostly motivated by bad software Avoiding DNSSEC management is mostly motivated by bad software
implementations. implementations.
- 3: Reducing the impact of CPE replacement on the Public Homenet - 3: Reducing the impact of HNA replacement on the Public Homenet
Zone. Unless the CPE private keys can be extracted and stored Zone. Unless the HNA private keys can be extracted and stored
off-device, CPE hardware replacement will result in an off-device, HNA hardware replacement will result in an
emergency key roll-over. This can be mitigated by using emergency key roll-over. This can be mitigated by using
relatively small TTLs. relatively small TTLs.
- 4: Reducing configuration impact on the end user. Unless there - 4: Reducing configuration impact on the end user. Unless there
are zero configuration mechanisms in place to provide are zero configuration mechanisms in place to provide
credentials between the new CPE and the Synchronization Server, credentials between the new HNA and the Synchronization Server,
authentication associations between the CPE and the authentication associations between the HNA and the
Synchronization Server would need to be re-configured. As CPE Synchronization Server would need to be re-configured. As HNA
replacement is not expected to happen regularly, end users may replacement is not expected to happen regularly, end users may
not be at ease with such configuration settings. However, not be at ease with such configuration settings. However,
mechanisms as described in mechanisms as described in
[I-D.ietf-homenet-naming-architecture-dhc-options] use DHCP [I-D.ietf-homenet-naming-architecture-dhc-options] use DHCP
Options to outsource the configuration and avoid this issue. Options to outsource the configuration and avoid this issue.
- 5: The Outsourcing Infrastructure is more likely to handle private - 5: The Outsourcing Infrastructure is more likely to handle private
keys more securely than the CPE. However, having all private keys more securely than the HNA. However, having all private
keys in one place may also nullify that benefit. keys in one place may also nullify that benefit.
6.2. Secure Delegation 6.2. Secure Delegation
Secure delegation is achieved only if the DS RRset is properly set in Secure delegation is achieved only if the DS RRset is properly set in
the parent zone. Secure delegation can be performed by the CPE or the parent zone. Secure delegation can be performed by the HNA or
the Outsourcing Infrastructures (that is the Synchronization Server the Outsourcing Infrastructures (that is the Synchronization Server
or the Public Authoritative Server(s)). or the Public Authoritative Server(s)).
The DS RRset can be updated manually with nsupdate for example. This The DS RRset can be updated manually with nsupdate for example. This
requires the CPE or the Outsourcing Infrastructure to be requires the HNA or the Outsourcing Infrastructure to be
authenticated by the DNS server hosting the parent of the Public authenticated by the DNS server hosting the parent of the Public
Homenet Zone. Such a trust channel between the CPE and the parent Homenet Zone. Such a trust channel between the HNA and the parent
DNS server may be hard to maintain with CPEs, and thus may be easier DNS server may be hard to maintain with HNAs, and thus may be easier
to establish with the Outsourcing Infrastructure. In fact, the to establish with the Outsourcing Infrastructure. In fact, the
Public Authoritative Server(s) may use Automating DNSSEC Delegation Public Authoritative Server(s) may use Automating DNSSEC Delegation
Trust Maintenance [RFC7344]. Trust Maintenance [RFC7344].
7. Handling Different Views 7. Handling Different Views
The Homenet Zone provides information about the home network. Some The Homenet Zone provides information about the home network. Some
users may be tempted to have provide responses dependent on the users may be tempted to have provide responses dependent on the
origin of the DNS query. More specifically, some users may be origin of the DNS query. More specifically, some users may be
tempted to provide a different view for DNS queries originating from tempted to provide a different view for DNS queries originating from
the home network and for DNS queries coming from the Internet. Each the home network and for DNS queries coming from the Internet. Each
view could then be associated with a dedicated Homenet Zone. Note view could then be associated with a dedicated Homenet Zone. Note
that this document does not specify how DNS queries originating from that this document does not specify how DNS queries originating from
the home network are addressed to the Homenet Zone. This could be the home network are addressed to the Homenet Zone. This could be
done via hosting the DNS resolver on the CPE for example. done via hosting the DNS resolver on the HNA for example.
This section is not normative. Section 7.1 details why some nodes This section is not normative. Section 7.1 details why some nodes
may only be reachable from the home network and not from the global may only be reachable from the home network and not from the global
Internet. Section 7.2 briefly describes the consequences of having Internet. Section 7.2 briefly describes the consequences of having
distinct views such as a "home network view" and an "Internet view". distinct views such as a "home network view" and an "Internet view".
Finally, Section 7.3 provides guidance on how to resolve names that Finally, Section 7.3 provides guidance on how to resolve names that
are only significant in the home network, without creating different are only significant in the home network, without creating different
views. views.
7.1. Misleading Reasons for Local Scope DNS Zone 7.1. Misleading Reasons for Local Scope DNS Zone
The motivation for supporting different views is to provide different The motivation for supporting different views is to provide different
answers dependent on the origin of the DNS query, for reasons such answers dependent on the origin of the DNS query, for reasons such
as: as:
- 1: An end user may want to have services not published on the - 1: An end user may want to have services not published on the
Internet. Services like the CPE administration interface that Internet. Services like the HNA administration interface that
provides the GUI to administer your CPE might not seem provides the GUI to administer your HNA might not seem
advisable to publish on the Internet. Similarly, services like advisable to publish on the Internet. Similarly, services like
the mapper that registers the devices of your home network may the mapper that registers the devices of your home network may
also not be desirable to be published on the Internet. In both also not be desirable to be published on the Internet. In both
cases, these services should only be known or used by the cases, these services should only be known or used by the
network administrator. To restrict the access of such network administrator. To restrict the access of such
services, the home network administrator may choose to publish services, the home network administrator may choose to publish
these pieces of information only within the home network, where these pieces of information only within the home network, where
it might be assumed that the users are more trusted than on the it might be assumed that the users are more trusted than on the
Internet. Even though this assumption may not be valid, at Internet. Even though this assumption may not be valid, at
least this may reduce the surface of any attack. least this may reduce the surface of any attack.
skipping to change at page 19, line 19 skipping to change at page 18, line 21
available. This may be especially inconvenient with devices with available. This may be especially inconvenient with devices with
multiple interfaces that are attached both to the Internet via a multiple interfaces that are attached both to the Internet via a
3G/4G interface and to the home network via a WLAN interface. 3G/4G interface and to the home network via a WLAN interface.
Devices may also cache the results of name resolution, and these Devices may also cache the results of name resolution, and these
cached entries may no longer be valid if a mobile device moves cached entries may no longer be valid if a mobile device moves
between a homenet connection and an internet connection e.g. a device between a homenet connection and an internet connection e.g. a device
temporarily loses wifi signal and switches to 3G. temporarily loses wifi signal and switches to 3G.
Regarding local-scope IP addresses, such devices may end up with poor Regarding local-scope IP addresses, such devices may end up with poor
connectivity. Suppose, for example, that DNS resolution is performed connectivity. Suppose, for example, that DNS resolution is performed
via the WLAN interface attached to the CPE, and the response provides via the WLAN interface attached to the HNA, and the response provides
local-scope IP addresses, but the communication is initiated on the local-scope IP addresses, but the communication is initiated on the
3G/4G interface. Communications with local-scope addresses will be 3G/4G interface. Communications with local-scope addresses will be
unreachable on the Internet, thus aborting the communication. The unreachable on the Internet, thus aborting the communication. The
same situation occurs if a device is flip / flopping between various same situation occurs if a device is flip / flopping between various
WLAN networks. WLAN networks.
Regarding DNSSEC, if the CPE does not sign the Homenet Zone and Regarding DNSSEC, if the HNA does not sign the Homenet Zone and
outsources the signing process, the two views are different, because outsources the signing process, the two views are different, because
one is protected with DNSSEC whereas the other is not. Devices with one is protected with DNSSEC whereas the other is not. Devices with
multiple interfaces will have difficulty securing the naming multiple interfaces will have difficulty securing the naming
resolution, as responses originating from the home network may not be resolution, as responses originating from the home network may not be
signed. signed.
For devices with all its interfaces attached to a single For devices with all its interfaces attached to a single
administrative domain, that is to say the home network, or the administrative domain, that is to say the home network, or the
Internet. Incoherence between DNS responses may still also occur if Internet. Incoherence between DNS responses may still also occur if
the device is able to perform DNS resolutions both using the DNS the device is able to perform DNS resolutions both using the DNS
resolving server of the home network, or one of the ISP. DNS resolving server of the home network, or one of the ISP. DNS
resolution performed via the CPE or the ISP resolver may be different resolution performed via the HNA or the ISP resolver may be different
than those performed over the Internet. than those performed over the Internet.
7.3. Guidance and Recommendations 7.3. Guidance and Recommendations
As documented in Section 7.2, it is RECOMMENDED to avoid different As documented in Section 7.2, it is RECOMMENDED to avoid different
views. If network administrators choose to implement multiple views, views. If network administrators choose to implement multiple views,
impacts on devices' resolution SHOULD be evaluated. impacts on devices' resolution SHOULD be evaluated.
As a consequence, the Homenet Zone is expected to be an exact copy of As a consequence, the Homenet Zone is expected to be an exact copy of
the Public Homenet Zone. As a result, services that are not expected the Public Homenet Zone. As a result, services that are not expected
to be published on the Internet SHOULD NOT be part of the Homenet to be published on the Internet SHOULD NOT be part of the Homenet
Zone, local-scope addresses SHOULD NOT be part of the Homenet Zone, Zone, local-scope addresses SHOULD NOT be part of the Homenet Zone,
and when possible, the CPE SHOULD sign the Homenet Zone. and when possible, the HNA SHOULD sign the Homenet Zone.
The Homenet Zone is expected to host public information only. It is The Homenet Zone is expected to host public information only. It is
not the scope of the DNS service to define local home network not the scope of the DNS service to define local home network
boundaries. Instead, local scope information is expected to be boundaries. Instead, local scope information is expected to be
provided to the home network using local scope naming services. mDNS provided to the home network using local scope naming services. mDNS
[RFC6762] DNS-SD [RFC6763] are two examples of these services. [RFC6762] DNS-SD [RFC6763] are two examples of these services.
Currently mDNS is limited to a single link network. However, future Currently mDNS is limited to a single link network. However, future
protocols are expected to leverage this constraint as pointed out in protocols are expected to leverage this constraint as pointed out in
[RFC7558]. [RFC7558].
8. Homenet Reverse Zone 8. Homenet Reverse Zone
This section is focused on the Homenet Reverse Zone. This section is focused on the Homenet Reverse Zone.
Firstly, all considerations for the Homenet Zone apply to the Homenet Firstly, all considerations for the Homenet Zone apply to the Homenet
Reverse Zone. The main difference between the Homenet Reverse Zone Reverse Zone. The main difference between the Homenet Reverse Zone
and the Homenet Zone is that the parent zone of the Homenet Reverse 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 Zone is most likely managed by the ISP. As the ISP also provides the
IP prefix to the CPE, it may be able to authenticate the CPE using 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 mechanisms outside the scope of this document e.g. the physical
attachment point to the ISP network. If the Reverse Synchronization attachment point to the ISP network. If the Reverse Synchronization
Server is managed by the ISP, credentials to authenticate the CPE for Server is managed by the ISP, credentials to authenticate the HNA for
the zone synchronization may be set automatically and transparently the zone synchronization may be set automatically and transparently
to the end user. [I-D.ietf-homenet-naming-architecture-dhc-options] to the end user. [I-D.ietf-homenet-naming-architecture-dhc-options]
describes how automatic configuration may be performed. describes how automatic configuration may be performed.
With IPv6, the domain space for IP addresses is so large that reverse With IPv6, the domain space for IP addresses is so large that reverse
zone may be confronted with scalability issues. How the reverse zone zone may be confronted with scalability issues. How the reverse zone
is generated is out of scope of this document. is generated is out of scope of this document.
[I-D.howard-dnsop-ip6rdns] provides guidance on how to address [I-D.howard-dnsop-ip6rdns] provides guidance on how to address
scalability issues. scalability issues.
skipping to change at page 23, line 7 skipping to change at page 22, line 7
Some DNS infrastructure uses the IP address to designate the Some DNS infrastructure uses the IP address to designate the
secondary, in which case, other mechanisms must be found. The reason secondary, in which case, other mechanisms must be found. The reason
for using IP addresses instead of names is generally to reach an for using IP addresses instead of names is generally to reach an
internal interface that is not designated by a FQDN, and to avoid internal interface that is not designated by a FQDN, and to avoid
potential bootstrap problems. Such scenarios are considered as out potential bootstrap problems. Such scenarios are considered as out
of scope in the case of home networks. of scope in the case of home networks.
10. Privacy Considerations 10. Privacy Considerations
Outsourcing the DNS Authoritative service from the CPE to a third Outsourcing the DNS Authoritative service from the HNA to a third
party raises a few privacy related concerns. party raises a few privacy related concerns.
The Homenet Zone contains a full description of the services hosted The Homenet Zone contains a full description of the services hosted
in the network. These services may not be expected to be publicly in the network. These services may not be expected to be publicly
shared although their names remain accessible through the Internet. shared although their names remain accessible through the Internet.
Even though DNS makes information public, the DNS does not expect to Even though DNS makes information public, the DNS does not expect to
make the complete list of services public. In fact, making make the complete list of services public. In fact, making
information public still requires the key (or FQDN) of each service information public still requires the key (or FQDN) of each service
to be known by the resolver in order to retrieve information about to be known by the resolver in order to retrieve information about
the services. More specifically, making mywebsite.example.com public the services. More specifically, making mywebsite.example.com public
in the DNS, is not sufficient to make resolvers aware of the in the DNS, is not sufficient to make resolvers aware of the
existence web site. However, an attacker may walk the reverse DNS existence web site. However, an attacker may walk the reverse DNS
zone, or use other reconnaissance techniques to learn this zone, or use other reconnaissance techniques to learn this
information as described in [I-D.ietf-opsec-ipv6-host-scanning]. information as described in [RFC7707].
In order to prevent the complete Homenet Zone being published on the In order to prevent the complete Homenet Zone being published on the
Internet, AXFR queries SHOULD be blocked on the Public Authoritative Internet, AXFR queries SHOULD be blocked on the Public Authoritative
Server(s). Similarly, to avoid zone-walking NSEC3 [RFC5155] SHOULD Server(s). Similarly, to avoid zone-walking NSEC3 [RFC5155] SHOULD
be preferred over NSEC [RFC4034]. be preferred over NSEC [RFC4034].
When the Homenet Zone is outsourced, the end user should be aware When the Homenet Zone is outsourced, the end user should be aware
that it provides a complete description of the services available on that it provides a complete description of the services available on
the home network. More specifically, names usually provides a clear the home network. More specifically, names usually provides a clear
indication of the service and possibly even the device type, and as indication of the service and possibly even the device type, and as
skipping to change at page 23, line 45 skipping to change at page 22, line 45
In addition to the Homenet Zone, the third party can also monitor the In addition to the Homenet Zone, the third party can also monitor the
traffic associated with the Homenet Zone. This traffic may provide traffic associated with the Homenet Zone. This traffic may provide
an indication of the services an end user accesses, plus how and when an indication of the services an end user accesses, plus how and when
they use these services. Although, caching may obfuscate this they use these services. Although, caching may obfuscate this
information inside the home network, it is likely that outside your information inside the home network, it is likely that outside your
home network this information will not be cached. home network this information will not be cached.
11. Security Considerations 11. Security Considerations
The Homenet Naming Architecture described in this document solves The Homenet Naming Architecture described in this document solves
exposing the CPE's DNS service as a DoS attack vector. exposing the HNA's DNS service as a DoS attack vector.
11.1. Names are less secure than IP addresses 11.1. Names are less secure than IP addresses
This document describes how an end user can make their services and This document describes how an end user can make their services and
devices from his home network reachable on the Internet by using devices from his home network reachable on the Internet by using
names rather than IP addresses. This exposes the home network to names rather than IP addresses. This exposes the home network to
attackers, since names are expected to include less entropy than IP attackers, since names are expected to include less entropy than IP
addresses. In fact, with IP addresses, the Interface Identifier is addresses. In fact, with IP addresses, the Interface Identifier is
64 bits long leading to up to 2^64 possibilities for a given 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 subnetwork. This is not to mention that the subnet prefix is also of
skipping to change at page 25, line 33 skipping to change at page 24, line 33
out the associated secondary's IP addresses in use. As a result, the 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 Hidden Primary is likely to limit the origin of its incoming traffic
based on the origin IP address. based on the origin IP address.
With filtering rules based on IP address, SOA flooding attacks are With filtering rules based on IP address, SOA flooding attacks are
limited to forged packets with the IP address of the secondary limited to forged packets with the IP address of the secondary
server. In other words, the only victims are the Hidden Primary server. In other words, the only victims are the Hidden Primary
itself or the secondary. There is a need for the Hidden Primary to 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 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 secondary, and to limit the resource needed to carry on the traffic
by the CPE hosting the Hidden Primary. On the other hand, mitigation by the HNA hosting the Hidden Primary. On the other hand, mitigation
should be performed appropriately, so as to limit the impact on the should be performed appropriately, so as to limit the impact on the
legitimate SOA sent by the secondary. legitimate SOA sent by the secondary.
The main reason for the Synchronization Server sending a SOA query is The main reason for the Synchronization Server sending a SOA query is
to update the SOA RRset after the TTL expires, to check the serial 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 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. 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 When a flood of SOA queries is received by the Hidden Primary, the
Hidden Primary may assume it is involved in an attack. Hidden Primary may assume it is involved in an attack.
There are few legitimate time slots when the secondary is expected to 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 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 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 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 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 + 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 T_REFRESH., and. Outside a few minutes following these specific time
slots, the probability that the CPE discards a legitimate SOA query slots, the probability that the HNA discards a legitimate SOA query
is very low. Within these time slots, the probability the secondary is very low. Within these time slots, the probability the secondary
may have its legitimate query rejected is higher. If a legitimate may have its legitimate query rejected is higher. If a legitimate
SOA is discarded, the secondary will re-send SOA query every "retry SOA is discarded, the secondary will re-send SOA query every "retry
time" second until "expire time" seconds occurs, where "retry time" time" second until "expire time" seconds occurs, where "retry time"
and "expire time" have been defined in the SOA. and "expire time" have been defined in the SOA.
As a result, it is RECOMMENDED to set rate limiting policies to As a result, it is RECOMMENDED to set rate limiting policies to
protect CPE resources. If a flood lasts more than the expired time protect HNA resources. If a flood lasts more than the expired time
defined by the SOA, it is RECOMMENDED to re-initiate a defined by the SOA, it is RECOMMENDED to re-initiate a
synchronization between the Hidden Primary and the secondaries. synchronization between the Hidden Primary and the secondaries.
11.3.2. Reflection Attacks involving the Synchronization Server 11.3.2. Reflection Attacks involving the Synchronization Server
The Synchronization Server acts as a secondary coupled with the The Synchronization Server acts as a secondary coupled with the
Hidden Primary. The secondary expects to receive NOTIFY query, SOA Hidden Primary. The secondary expects to receive NOTIFY query, SOA
responses, AXFR and IXFR responses from the Hidden Primary. responses, AXFR and IXFR responses from the Hidden Primary.
Sending a NOTIFY query to the secondary generates a NOTIFY response Sending a NOTIFY query to the secondary generates a NOTIFY response
as well as initiating an SOA query exchange from the secondary to the as well as initiating an SOA query exchange from the secondary to the
Hidden Primary. As mentioned in [RFC1996], this is a known "benign Hidden Primary. As mentioned in [RFC1996], this is a known "benign
denial of service attack". As a result, the Synchronization Server denial of service attack". As a result, the Synchronization Server
SHOULD enforce rate limiting on sending SOA queries and NOTIFY SHOULD enforce rate limiting on sending SOA queries and NOTIFY
responses to the Hidden Primary. Most likely, when the secondary is responses to the Hidden Primary. Most likely, when the secondary is
flooded with valid and signed NOTIFY queries, it is under a replay flooded with valid and signed NOTIFY queries, it is under a replay
attack which is discussed in Section 11.5. The key thing here is attack which is discussed in Section 11.5. The key thing here is
that the secondary is likely to be designed to be able to process that the secondary is likely to be designed to be able to process
much more traffic than the Hidden Primary hosted on a CPE. much more traffic than the Hidden Primary hosted on a HNA.
This paragraph details how the secondary may limit the NOTIFY This paragraph details how the secondary may limit the NOTIFY
queries. Because the Hidden Primary may be renumbered, the secondary queries. Because the Hidden Primary may be renumbered, the secondary
SHOULD NOT perform permanent IP filtering based on IP addresses. In SHOULD NOT perform permanent IP filtering based on IP addresses. In
addition, a given secondary may be shared among multiple Hidden addition, a given secondary may be shared among multiple Hidden
Primaries which make filtering rules based on IP harder to set. The 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 time at which a NOTIFY is sent by the Hidden Primary is not
predictable. However, a flood of NOTIFY messages may be easily predictable. However, a flood of NOTIFY messages may be easily
detected, as a NOTIFY originated from a given Homenet Zone is detected, as a NOTIFY originated from a given Homenet Zone is
expected to have a very limited number of unique source IP addresses, expected to have a very limited number of unique source IP addresses,
skipping to change at page 27, line 14 skipping to change at page 26, line 14
11.3.3. Reflection Attacks involving the Public Authoritative Servers 11.3.3. Reflection Attacks involving the Public Authoritative Servers
Reflection attacks involving the Public Authoritative Server(s) are Reflection attacks involving the Public Authoritative Server(s) are
similar to attacks on any Outsourcing Infrastructure. This is not similar to attacks on any Outsourcing Infrastructure. This is not
specific to the architecture described in this document, and thus are specific to the architecture described in this document, and thus are
considered as out of scope. considered as out of scope.
In fact, one motivation of the architecture described in this In fact, one motivation of the architecture described in this
document is to expose the Public Authoritative Server(s) to attacks document is to expose the Public Authoritative Server(s) to attacks
instead of the CPE, as it is believed that the Public Authoritative instead of the HNA, as it is believed that the Public Authoritative
Server(s) will be better able to defend itself. Server(s) will be better able to defend itself.
11.4. Flooding Attack 11.4. Flooding Attack
The purpose of flooding attacks is mostly resource exhaustion, where The purpose of flooding attacks is mostly resource exhaustion, where
the resource can be bandwidth, memory, or CPU for example. the resource can be bandwidth, memory, or CPU for example.
One goal of the architecture described in this document is to limit One goal of the architecture described in this document is to limit
the surface of attack on the CPE. This is done by outsourcing the 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 DNS service to the Public Authoritative Server(s). By doing so, the
CPE limits its DNS interactions between the Hidden Primary and the HNA limits its DNS interactions between the Hidden Primary and the
Synchronization Server. This limits the number of entities the CPE Synchronization Server. This limits the number of entities the HNA
interacts with as well as the scope of DNS exchanges - NOTIFY, SOA, interacts with as well as the scope of DNS exchanges - NOTIFY, SOA,
AXFR, IXFR. AXFR, IXFR.
The use of an authenticated channel with SIG(0) or TSIG between the The use of an authenticated channel with SIG(0) or TSIG between the
CPE and the Synchronization Server, enables detection of illegitimate HNA and the Synchronization Server, enables detection of illegitimate
DNS queries, so appropriate action may be taken - like dropping the DNS queries, so appropriate action may be taken - like dropping the
queries. If signatures are validated, then most likely, the CPE is queries. If signatures are validated, then most likely, the HNA is
under a replay attack, as detailed in Section 11.5 under a replay attack, as detailed in Section 11.5
In order to limit the resource required for authentication, it is In order to limit the resource required for authentication, it is
recommended to use TSIG that uses symmetric cryptography over SIG(0) recommended to use TSIG that uses symmetric cryptography over SIG(0)
that uses asymmetric cryptography. that uses asymmetric cryptography.
11.5. Replay Attack 11.5. Replay Attack
Replay attacks consist of an attacker either resending or delaying a Replay attacks consist of an attacker either resending or delaying a
legitimate message that has been sent by an authorized user or legitimate message that has been sent by an authorized user or
skipping to change at page 28, line 33 skipping to change at page 27, line 33
13. Acknowledgment 13. Acknowledgment
The authors wish to thank Philippe Lemordant for its contributions on The authors wish to thank Philippe Lemordant for its contributions on
the early versions of the draft; Ole Troan for pointing out issues the early versions of the draft; Ole Troan for pointing out issues
with the IPv6 routed home concept and placing the scope of this with the IPv6 routed home concept and placing the scope of this
document in a wider picture; Mark Townsley for encouragement and document in a wider picture; Mark Townsley for encouragement and
injecting a healthy debate on the merits of the idea; Ulrik de Bie injecting a healthy debate on the merits of the idea; Ulrik de Bie
for providing alternative solutions; Paul Mockapetris, Christian for providing alternative solutions; Paul Mockapetris, Christian
Jacquenet, Francis Dupont and Ludovic Eschard for their remarks on Jacquenet, Francis Dupont and Ludovic Eschard for their remarks on
CPE and low power devices; Olafur Gudmundsson for clarifying DNSSEC HNA and low power devices; Olafur Gudmundsson for clarifying DNSSEC
capabilities of small devices; Simon Kelley for its feedback as capabilities of small devices; Simon Kelley for its feedback as
dnsmasq implementer; Andrew Sullivan, Mark Andrew, Ted Lemon, Mikael dnsmasq implementer; Andrew Sullivan, Mark Andrew, Ted Lemon, Mikael
Abrahamson, Michael Richardson and Ray Bellis for their feedback on Abrahamson, Michael Richardson and Ray Bellis for their feedback on
handling different views as well as clarifying the impact of handling different views as well as clarifying the impact of
outsourcing the zone signing operation outside the CPE; Mark Andrew outsourcing the zone signing operation outside the HNA; Mark Andrew
and Peter Koch for clarifying the renumbering. and Peter Koch for clarifying the renumbering.
14. References 14. References
14.1. Normative References 14.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<http://www.rfc-editor.org/info/rfc1034>. <http://www.rfc-editor.org/info/rfc1034>.
skipping to change at page 29, line 14 skipping to change at page 28, line 14
[RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995,
DOI 10.17487/RFC1995, August 1996, DOI 10.17487/RFC1995, August 1996,
<http://www.rfc-editor.org/info/rfc1995>. <http://www.rfc-editor.org/info/rfc1995>.
[RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone [RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone
Changes (DNS NOTIFY)", RFC 1996, DOI 10.17487/RFC1996, Changes (DNS NOTIFY)", RFC 1996, DOI 10.17487/RFC1996,
August 1996, <http://www.rfc-editor.org/info/rfc1996>. August 1996, <http://www.rfc-editor.org/info/rfc1996>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ Requirement Levels", BCP 14, RFC 2119,
RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,
"Dynamic Updates in the Domain Name System (DNS UPDATE)", "Dynamic Updates in the Domain Name System (DNS UPDATE)",
RFC 2136, DOI 10.17487/RFC2136, April 1997, RFC 2136, DOI 10.17487/RFC2136, April 1997,
<http://www.rfc-editor.org/info/rfc2136>. <http://www.rfc-editor.org/info/rfc2136>.
[RFC2142] Crocker, D., "Mailbox Names for Common Services, Roles and [RFC2142] Crocker, D., "Mailbox Names for Common Services, Roles and
Functions", RFC 2142, DOI 10.17487/RFC2142, May 1997, Functions", RFC 2142, DOI 10.17487/RFC2142, May 1997,
<http://www.rfc-editor.org/info/rfc2142>. <http://www.rfc-editor.org/info/rfc2142>.
skipping to change at page 30, line 19 skipping to change at page 29, line 19
[RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol", [RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol",
RFC 4960, DOI 10.17487/RFC4960, September 2007, RFC 4960, DOI 10.17487/RFC4960, September 2007,
<http://www.rfc-editor.org/info/rfc4960>. <http://www.rfc-editor.org/info/rfc4960>.
[RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS [RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
Security (DNSSEC) Hashed Authenticated Denial of Security (DNSSEC) Hashed Authenticated Denial of
Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008, Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008,
<http://www.rfc-editor.org/info/rfc5155>. <http://www.rfc-editor.org/info/rfc5155>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/ (TLS) Protocol Version 1.2", RFC 5246,
RFC5246, August 2008, DOI 10.17487/RFC5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>. <http://www.rfc-editor.org/info/rfc5246>.
[RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol [RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol
(AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010, (AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010,
<http://www.rfc-editor.org/info/rfc5936>. <http://www.rfc-editor.org/info/rfc5936>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <http://www.rfc-editor.org/info/rfc6347>. January 2012, <http://www.rfc-editor.org/info/rfc6347>.
[RFC6644] Evans, D., Droms, R., and S. Jiang, "Rebind Capability in [RFC6644] Evans, D., Droms, R., and S. Jiang, "Rebind Capability in
DHCPv6 Reconfigure Messages", RFC 6644, DOI 10.17487/ DHCPv6 Reconfigure Messages", RFC 6644,
RFC6644, July 2012, DOI 10.17487/RFC6644, July 2012,
<http://www.rfc-editor.org/info/rfc6644>. <http://www.rfc-editor.org/info/rfc6644>.
[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, [RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
DOI 10.17487/RFC6762, February 2013, DOI 10.17487/RFC6762, February 2013,
<http://www.rfc-editor.org/info/rfc6762>. <http://www.rfc-editor.org/info/rfc6762>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013, Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
<http://www.rfc-editor.org/info/rfc6763>. <http://www.rfc-editor.org/info/rfc6763>.
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2 Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <http://www.rfc-editor.org/info/rfc7296>. 2014, <http://www.rfc-editor.org/info/rfc7296>.
[RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking
Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April
2016, <http://www.rfc-editor.org/info/rfc7788>.
14.2. Informational References 14.2. Informational References
[I-D.howard-dnsop-ip6rdns] [I-D.howard-dnsop-ip6rdns]
Howard, L., "Reverse DNS in IPv6 for Internet Service Howard, L., "Reverse DNS in IPv6 for Internet Service
Providers", draft-howard-dnsop-ip6rdns-00 (work in Providers", draft-howard-dnsop-ip6rdns-00 (work in
progress), June 2014. progress), June 2014.
[I-D.ietf-homenet-naming-architecture-dhc-options] [I-D.ietf-homenet-naming-architecture-dhc-options]
Migault, D., Cloetens, W., Griffiths, C., and R. Weber, Migault, D., Mrugalski, T., Griffiths, C., Weber, R., and
"DHCP Options for Homenet Naming Architecture", draft- W. Cloetens, "DHCPv6 Options for Homenet Naming
ietf-homenet-naming-architecture-dhc-options-02 (work in Architecture", draft-ietf-homenet-naming-architecture-dhc-
progress), May 2015. options-03 (work in progress), October 2015.
[I-D.ietf-opsec-ipv6-host-scanning]
Gont, F. and T. Chown, "Network Reconnaissance in IPv6
Networks", draft-ietf-opsec-ipv6-host-scanning-08 (work in
progress), August 2015.
[RFC1033] Lottor, M., "Domain Administrators Operations Guide", RFC [RFC1033] Lottor, M., "Domain Administrators Operations Guide",
1033, DOI 10.17487/RFC1033, November 1987, RFC 1033, DOI 10.17487/RFC1033, November 1987,
<http://www.rfc-editor.org/info/rfc1033>. <http://www.rfc-editor.org/info/rfc1033>.
[RFC4192] Baker, F., Lear, E., and R. Droms, "Procedures for [RFC4192] Baker, F., Lear, E., and R. Droms, "Procedures for
Renumbering an IPv6 Network without a Flag Day", RFC 4192, Renumbering an IPv6 Network without a Flag Day", RFC 4192,
DOI 10.17487/RFC4192, September 2005, DOI 10.17487/RFC4192, September 2005,
<http://www.rfc-editor.org/info/rfc4192>. <http://www.rfc-editor.org/info/rfc4192>.
[RFC7010] Liu, B., Jiang, S., Carpenter, B., Venaas, S., and W. [RFC7010] Liu, B., Jiang, S., Carpenter, B., Venaas, S., and W.
George, "IPv6 Site Renumbering Gap Analysis", RFC 7010, George, "IPv6 Site Renumbering Gap Analysis", RFC 7010,
DOI 10.17487/RFC7010, September 2013, DOI 10.17487/RFC7010, September 2013,
<http://www.rfc-editor.org/info/rfc7010>. <http://www.rfc-editor.org/info/rfc7010>.
[RFC7344] Kumari, W., Gudmundsson, O., and G. Barwood, "Automating [RFC7344] Kumari, W., Gudmundsson, O., and G. Barwood, "Automating
DNSSEC Delegation Trust Maintenance", RFC 7344, DOI DNSSEC Delegation Trust Maintenance", RFC 7344,
10.17487/RFC7344, September 2014, DOI 10.17487/RFC7344, September 2014,
<http://www.rfc-editor.org/info/rfc7344>. <http://www.rfc-editor.org/info/rfc7344>.
[RFC7368] Chown, T., Ed., Arkko, J., Brandt, A., Troan, O., and J. [RFC7368] Chown, T., Ed., Arkko, J., Brandt, A., Troan, O., and J.
Weil, "IPv6 Home Networking Architecture Principles", RFC Weil, "IPv6 Home Networking Architecture Principles",
7368, DOI 10.17487/RFC7368, October 2014, RFC 7368, DOI 10.17487/RFC7368, October 2014,
<http://www.rfc-editor.org/info/rfc7368>. <http://www.rfc-editor.org/info/rfc7368>.
[RFC7558] Lynn, K., Cheshire, S., Blanchet, M., and D. Migault, [RFC7558] Lynn, K., Cheshire, S., Blanchet, M., and D. Migault,
"Requirements for Scalable DNS-Based Service Discovery "Requirements for Scalable DNS-Based Service Discovery
(DNS-SD) / Multicast DNS (mDNS) Extensions", RFC 7558, DOI (DNS-SD) / Multicast DNS (mDNS) Extensions", RFC 7558,
10.17487/RFC7558, July 2015, DOI 10.17487/RFC7558, July 2015,
<http://www.rfc-editor.org/info/rfc7558>. <http://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,
<http://www.rfc-editor.org/info/rfc7707>.
Appendix A. Document Change Log Appendix A. Document Change Log
[RFC Editor: This section is to be removed before publication] [RFC Editor: This section is to be removed before publication]
-08 -08
- 1: Clarification of the meaning of CPE. The architecture does not - 1: Clarification of the meaning of CPE. The architecture does not
consider a single CPE. The CPE represents multiple functions. consider a single CPE. The CPE represents multiple functions.
-07: -07:
 End of changes. 122 change blocks. 
276 lines changed or deleted 246 lines changed or added

This html diff was produced by rfcdiff 1.45. The latest version is available from http://tools.ietf.org/tools/rfcdiff/