draft-ietf-homenet-front-end-naming-delegation-00.txt   draft-ietf-homenet-front-end-naming-delegation-01.txt 
HOMENET D. Migault (Ed) HOMENET D. Migault (Ed)
Internet-Draft Orange Internet-Draft Ericsson
Intended status: Standards Track W. Cloetens Intended status: Standards Track W. Cloetens
Expires: March 22, 2015 SoftAtHome Expires: August 20, 2015 SoftAtHome
C. Griffiths C. Griffiths
Dyn Dyn
R. Weber R. Weber
Nominum Nominum
September 18, 2014 February 16, 2015
Outsourcing Home Network Authoritative Naming Service Outsourcing Home Network Authoritative Naming Service
draft-ietf-homenet-front-end-naming-delegation-00.txt draft-ietf-homenet-front-end-naming-delegation-01.txt
Abstract Abstract
CPEs are designed to provide IP connectivity to home networks. Most CPEs are designed to provide IP connectivity to home networks. Most
CPEs assign IP addresses to the nodes of the home network which makes CPEs assign IP addresses to the nodes of the home network which makes
it a good candidate for hosting the naming service. With IPv6, the it a good candidate for hosting the naming service. With IPv6, the
naming service makes nodes reachable from the home network as well as naming service makes nodes reachable from the home network as well as
from the Internet. from the Internet.
However, CPEs have not been designed to host such a naming service However, CPEs have not been designed to host such a naming service
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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 22, 2015. This Internet-Draft will expire on August 20, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2015 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
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 2, line 39 skipping to change at page 2, line 39
1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Architecture Description . . . . . . . . . . . . . . . . . . 5 4. Architecture Description . . . . . . . . . . . . . . . . . . 5
4.1. Architecture Overview . . . . . . . . . . . . . . . . . . 5 4.1. Architecture Overview . . . . . . . . . . . . . . . . . . 5
4.2. Example: DNS(SEC) Homenet Zone . . . . . . . . . . . . . 7 4.2. Example: DNS(SEC) Homenet Zone . . . . . . . . . . . . . 7
4.3. Example: CPE necessary parameters for outsourcing . . . . 9 4.3. Example: CPE necessary parameters for outsourcing . . . . 9
5. Synchronization between CPE and Public Authoritative Servers 10 5. Synchronization between CPE and Public Authoritative Servers 10
5.1. Synchronization with a Hidden Master . . . . . . . . . . 10 5.1. Synchronization with a Hidden Master . . . . . . . . . . 10
5.2. Securing Synchronization . . . . . . . . . . . . . . . . 11 5.2. Securing Synchronization . . . . . . . . . . . . . . . . 11
5.3. CPE Security Policies . . . . . . . . . . . . . . . . . . 12 5.3. CPE Security Policies . . . . . . . . . . . . . . . . . . 13
6. DNSSEC compliant Homenet Architecture . . . . . . . . . . . . 13 6. DNSSEC compliant Homenet Architecture . . . . . . . . . . . . 13
6.1. Zone Signing . . . . . . . . . . . . . . . . . . . . . . 13 6.1. Zone Signing . . . . . . . . . . . . . . . . . . . . . . 13
6.2. Secure Delegation . . . . . . . . . . . . . . . . . . . . 15 6.2. Secure Delegation . . . . . . . . . . . . . . . . . . . . 15
7. Handling Different Views . . . . . . . . . . . . . . . . . . 15 7. Handling Different Views . . . . . . . . . . . . . . . . . . 15
8. Reverse Zone . . . . . . . . . . . . . . . . . . . . . . . . 15 7.1. Motivations . . . . . . . . . . . . . . . . . . . . . . . 16
9. Security Considerations . . . . . . . . . . . . . . . . . . . 16 7.2. Consequences . . . . . . . . . . . . . . . . . . . . . . 16
9.1. Names are less secure than IP addresses . . . . . . . . . 16 7.3. Guidance and Recommendations . . . . . . . . . . . . . . 17
9.2. Names are less volatile than IP addresses . . . . . . . . 16 8. Reverse Zone . . . . . . . . . . . . . . . . . . . . . . . . 17
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 18
11. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 16 10. Security Considerations . . . . . . . . . . . . . . . . . . . 19
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 10.1. Names are less secure than IP addresses . . . . . . . . 19
12.1. Normative References . . . . . . . . . . . . . . . . . . 17 10.2. Names are less volatile than IP addresses . . . . . . . 19
12.2. Informational References . . . . . . . . . . . . . . . . 18 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
12. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 20
Appendix A. Document Change Log . . . . . . . . . . . . . . . . 19 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 13.1. Normative References . . . . . . . . . . . . . . . . . . 20
13.2. Informational References . . . . . . . . . . . . . . . . 21
Appendix A. Document Change Log . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
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. To access services IPv6 provides global end to end IP reachability. To access services
hosted in the home network with IPv6 addresses, end users prefer to hosted in the home network with IPv6 addresses, end users prefer to
use names instead of long and complex IPv6 addresses. use names instead of long and complex IPv6 addresses.
CPEs are already providing IPv6 connectivity to the home network and CPEs 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 the CPEs a good candidate to manage binding network. This makes the CPEs a good candidate to manage binding
between names and IP addresses of the nodes. In addition, between names and IP addresses of the nodes. In addition, [RFC7368]
[I-D.ietf-homenet-arch] recommends that home networks be resilient to recommends that home networks be resilient to connectivity disruption
connectivity disruption from the ISP. This requires that a dedicate from the ISP. This requires that a dedicate device inside the home
device inside the home network manage bindings between names and IP network manage bindings between names and IP addresses of the nodes
addresses of the nodes and builds the DNS Homenet Zone. All this and builds the DNS Homenet Zone. All this makes the CPE the natural
makes the CPE the natural candidate for setting the DNS(SEC) zone candidate for setting the DNS(SEC) zone file of the home network.
file of the home network.
CPEs are usually low powered devices designed for the home network, CPEs are usually low powered devices designed for the home network,
but not for heavy traffic. As a result, hosting the an authoritative but not for heavy traffic. As a result, hosting the an authoritative
DNS service on the Internet may expose the home network to resource DNS service on the Internet may expose the home network to resource
exhaustion, which may isolate the home network from the Internet and exhaustion, which may isolate the home network from the Internet and
affect the services hosted by the CPEs, thus affecting the overall affect the services hosted by the CPEs, thus affecting the overall
home network communications. home network communications.
In order to avoid resource exhaustion, this document describes an In order to avoid resource exhaustion, this document describes an
architecture that outsources the authoritative naming service of the architecture that outsources the authoritative naming service of the
home network. More specifically, the DNS(SEC) Homenet Zone built by home network. More specifically, the DNS(SEC) Homenet Zone built by
the CPE is outsourced to Public Authoritative Servers. These servers the CPE is outsourced to Public Authoritative Servers. These servers
publish the corresponding DN(SEC) Public Zone on the Internet. publish the corresponding DN(SEC) Public Zone on the Internet.
Section 4.1 describes the architecture. In order to keep the Section 4.1 describes the architecture. In order to keep the
DNS(SEC) Public Zone up-to-date Section 5 describes how the DNS(SEC) DNS(SEC) Public Zone up-to-date Section 5 describes how the DNS(SEC)
Homenet Zone and the DN(SEC) Public Zone can be synchronized. The Homenet Zone and the DN(SEC) Public Zone can be synchronized. The
proposed architecture aims at deploying DNSSEC and the DNS(SEC) proposed architecture aims at deploying DNSSEC and the DNS(SEC)
Public Zone is expected to be signed with a secure delegation. The Public Zone is expected to be signed with a secure delegation. The
zone signing and secure delegation can be performed either by the CPE zone signing and secure delegation can be performed either by the CPE
or by the Public Authoritative Servers. Section 6 discusses these or by the Public Authoritative Servers. Section 6 discusses these
two alternatives. Section 7 discusses the impact of multiple views two alternatives. Section 7 discusses multiple views aspects and
and Section 8 discusses the case of the reverse zone. provide guidance to avoid them. Section 8 discusses the case of the
reverse zone. Section 9 and Section 10 respectively discuss privacy
and security considerations when outsourcing the DNS Homenet Zone.
3. Terminology 3. Terminology
- Customer Premises Equipment: (CPE) is the router providing - Customer Premises Equipment: (CPE) is the router providing
connectivity to the home network. It is configured and managed connectivity to the home network. It is configured and managed
by the end user. In this document, the CPE MAY also hosts by the end user. In this document, the CPE MAY also hosts
services such as DHCPv6. This device MAY be provided by the services such as DHCPv6. This device MAY be provided by the
ISP. ISP.
- Registered Homenet Domain: is the Domain Name associated to the - Registered Homenet Domain: is the Domain Name associated to the
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necessary parameters the CPE needs to outsource the authoritative necessary parameters the CPE needs to outsource the authoritative
naming service. These two section are informational and non naming service. These two section 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 DNS(SEC) Homenet Zone -- example.com in Figure 1. The CPE builds the DNS(SEC) Homenet Zone
associated to the home network. The content of the DNS(SEC) Homenet associated to the home network. How the DNS(SEC) Homenet Zone is
Zone is out of the scope of this document. The CPE may host and built is out of the scope of this document. The CPE may host and
involve multiple services like a web GUI, DHCP [RFC6644] or mDNS involve multiple services like a web GUI, DHCP [RFC6644] or mDNS
[RFC6762]. These services may coexist and may be used to populate [RFC6762]. These services may coexist and may be used to populate
the DNS Homenet Zone. This document assumes the DNS(SEC) Homenet the DNS Homenet Zone. This document assumes the DNS(SEC) Homenet
Zone has been populated with domain names that are intended to be Zone has been populated with domain names that are intended to be
publicly published and that are publicly reachable. More publicly published and that are publicly reachable. More
specifically, names associated to services or devices that are not specifically, names associated to services or devices that are not
expected to be reachable from outside the home network or names bound expected to be reachable from outside the home network or names bound
to non globally reachable IP addresses MUST NOT be part of the to non globally reachable IP addresses MUST NOT be part of the
DNS(SEC) Homenet Zone. DNS(SEC) Homenet Zone.
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| DNSSEC Resolver | | DNSSEC Resolver |
| | | |
+----------------------+ +----------------------+
Figure 1: Homenet Naming Architecture Description Figure 1: Homenet Naming Architecture Description
The Public Authoritative Servers are described in Figure 2. The The Public Authoritative Servers are described in Figure 2. The
Public Authoritative Name Server Set receives the DNS(SEC) Homenet Public Authoritative Name Server Set receives the DNS(SEC) Homenet
Zone as an input. The received zone may be transformed to output the Zone as an input. The received zone may be transformed to output the
DNS(SEC) Public Zone. Various operations may be performed here, DNS(SEC) Public Zone. Various operations may be performed here,
however the one this document considers here is zone signing when the however this document only considers zone signing as potential
CPE outsources this operation. Implications of such policy are operation. This could occur only when the CPE outsources this
detailed in Section 6 and Section 7. operation to the Public Authoritative Name Server Set. On the other
hand, if the CPE signs the DNSSEC Homenet Zone itself, the zone it
collected by the Public Authoritative Name Server Set and directly
transferred to the Public Authoritative Master. Implications of such
policy are detailed in Section 6 and Section 7.
Internet Internet
+--------------------------------------------------------+ +--------------------------------------------------------+
| Public Authoritative Servers | | Public Authoritative Servers |
+--------------------------------------------------------+ +--------------------------------------------------------+
+----------------------+ +----------------------+ +----------------------+ +----------------------+
| | | | | | | |
| Public Authoritative | | Public Authoritative | | Public Authoritative | | Public Authoritative |
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@ NS public.authoritative.servers.example.net @ NS public.authoritative.servers.example.net
public.masters.example.net A @IP1 public.masters.example.net A @IP1
public.masters.example.net A @IP2 public.masters.example.net A @IP2
public.masters.example.net AAAA @IP3 public.masters.example.net AAAA @IP3
public.masters.example.net AAAA @IP4 public.masters.example.net AAAA @IP4
Figure 3: DNS Homenet Zone Figure 3: DNS Homenet Zone
The SOA RRset is defined in [RFC1033], [RFC1035]. This SOA is The SOA RRset is defined in [RFC1033], [RFC1035] and [RFC2308]. This
specific as it is used for the synchronization between the Hidden SOA is specific as it is used for the synchronization between the
Master and the Public Authoritative Name Server Set and published on Hidden Master and the Public Authoritative Name Server Set and
the DNS Public Authoritative Master. published on the DNS Public Authoritative Master.
- MNAME: indicates the primary master. In our case the zone is - MNAME: indicates the primary master. In our case the zone is
published on the Public Authoritative Master, and its name MUST published on the Public Authoritative Master, and its name MUST
be mentioned. If multiple Public Authoritative Masters are be mentioned. If multiple Public Authoritative Masters are
involved, one of them MUST be chosen. More specifically, the involved, one of them MUST be chosen. More specifically, the
CPE MUST NOT place the name of the Hidden Master. CPE MUST NOT place the name of the Hidden Master.
- RNAME: indicates the email address to reach the administrator. - RNAME: indicates the email address to reach the administrator.
[RFC2142] recommends to use hostmaster@domain and replacing the [RFC2142] recommends to use hostmaster@domain and replacing the
'@' sign by '.'. '@' sign by '.'.
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the transactions between the Public Authoritative Servers and the the transactions between the Public Authoritative Servers and the
CPE. The advantage of TLS/DTLS is that this technology is widely CPE. The advantage of TLS/DTLS is that this technology is widely
deployed, and most of the boxes already embeds a TLS/DTLS libraries, deployed, and most of the boxes already embeds a TLS/DTLS libraries,
eventually taking advantage of hardware acceleration. Then TLS/DTLS eventually taking advantage of hardware acceleration. Then TLS/DTLS
provides authentication facilities and can use certificates to provides authentication facilities and can use certificates to
authenticate the Public Authoritative Server and the CPE. On the authenticate the Public Authoritative Server and the CPE. On the
other hand, using TLS/DTLS requires to integrate DNS exchange over other hand, using TLS/DTLS requires to integrate DNS exchange over
TLS/DTLS, as well as a new service port. This is why we do not TLS/DTLS, as well as a new service port. This is why we do not
recommend this option. recommend this option.
IPsec [RFC4301] IKEv2 [RFC5996] can also be used to secure the IPsec [RFC4301] IKEv2 [RFC7296] can also be used to secure the
transactions between the CPE and the Public Authoritative Servers. transactions between the CPE and the Public Authoritative Servers.
Similarly to TLS/DTLS, most CPE already embeds a IPsec stack, and Similarly to TLS/DTLS, most CPE already embeds a IPsec stack, and
IKEv2 provides multiple authentications possibilities with its EAP IKEv2 provides multiple authentications possibilities with its EAP
framework. In addition, IPsec can be used to protect the DNS framework. In addition, IPsec can be used to protect the DNS
exchanges between the CPE and the Public Authoritative Servers exchanges between the CPE and the Public Authoritative Servers
without any modifications of the DNS Servers or client. DNS without any modifications of the DNS Servers or client. DNS
integration over IPsec only requires an additional security policy in integration over IPsec only requires an additional security policy in
the Security Policy Database. One disadvantage of IPsec is that it the Security Policy Database. One disadvantage of IPsec is that it
hardly goes through NATs and firewalls. However, in our case, the hardly goes through NATs and firewalls. However, in our case, the
CPE is connected to the Internet, and IPsec communication between the CPE is connected to the Internet, and IPsec communication between the
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NOTIFY query, SOA response, IXFR response or AXFR responses. NOTIFY query, SOA response, IXFR response or AXFR responses.
The Hidden Master SHOULD drop any incoming packets other than DNS The Hidden Master SHOULD drop any incoming packets other than DNS
NOTIFY response, SOA query, IXFR query or AXFR query. NOTIFY response, SOA query, IXFR query or AXFR query.
The Hidden Master SHOULD drop any non protected IXFR or AXFR The Hidden Master SHOULD drop any non protected IXFR or AXFR
exchange. This depends how the synchronization is secured. exchange. This depends how the synchronization is secured.
6. DNSSEC compliant Homenet Architecture 6. DNSSEC compliant Homenet Architecture
[I-D.ietf-homenet-arch] in Section 3.7.3 recommends DNSSEC to be [RFC7368] in Section 3.7.3 recommends DNSSEC to be deployed on the
deployed on the both the authoritative server and the resolver. The both the authoritative server and the resolver. The resolver side is
resolver side is out of scope of this document, and only the out of scope of this document, and only the authoritative part is
authoritative part is considered. 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 by delegation. As described in Section 4.1, signing can be performed by
the CPE or by the Public Authoritative Servers. Section 6.1 details the CPE or by the Public Authoritative Servers. Section 6.1 details
the implications of these two alternatives. Similarly, the secure the implications of these two alternatives. Similarly, the secure
delegation can be performed by the CPE or by the Public Authoritative delegation can be performed by the CPE or by the Public Authoritative
Servers. Section 6.2 discusses these two alternatives. Servers. 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 Public Authoritative Servers. It is performed by the CPE or by the Public Authoritative Servers. It is
recommended to sign the zone by the CPE unless there is a strong recommended to sign the zone by the CPE unless there is a strong
argument against it, like a CPE that is not able to sign the zone. argument against it, like a CPE that is not able to sign the zone.
In that case zone signing may be performed by the Public In that case zone signing may be performed by the Public
Authoritative Servers on behalf of the CPE. Authoritative Servers on behalf of the CPE.
Reasons for signing the zone by the CPE are: Reasons for signing the zone by the CPE are:
- 1: Keeping the Homenet Zone and the Public Zone equals. This - 1: Keeping the Homenet Zone and the Public Zone equals to securely
aspect is discussed in detail in Section 7. More specifically, optimize DNS resolution. As the Public Zone is signed with
if the CPE signs the DNS Homenet Zone, then, the CPE has the DNSSEC, RRsets are authenticated and thus DNS responses can be
ability to host the authoritative naming service of the homenet validated even though they are not provided by the
for DNSSEC queries coming from within the network. As a authoritative server. This provides the CPE the ability to
result, a query will be resolved the same way whether it is respond on behalf of the Public Authoritative Master. This
sent from the home network or from the Internet. On the other could be useful for example if, in the future, the CPE could
hand, if the CPE does not sign the DNS Homenet Zone, either it announce to the home network that the CPE can act a a local
acts as an authoritative server for the home network or not. authoritative master or equivalent for the Homenet Zone.
If the CPE is an authoritative server for queries initiated Currently the CPE is not expected to receive authoritative DNS
from within the home network, then nodes connected to both queries as its IP address is not mentioned in the Public Zone.
networks-- the home network and the Internet -- do not have a On the other hand most CPE host a resolving function, and could
unique resolution. Devices that may be impacted are mobile be configured to perform a local lookup to the Homenet Zone
phones with Radio Access Network interfaces and WLAN instead of initiating a DNS exchange with the Public
interfaces. Alternatively if the CPE does not act as an Authoritative Master. Note that outsourcing the zone signing
authoritative server, it goes against the principles operation requires that all DNSSEC queries be cached to perform
connectivity disruption independence exposed in a local lookup, otherwise a resolution with the Public
[I-D.ietf-homenet-arch] section 4.4.1 and 3.7.5. In case of Authoritative Master is performed.
connectivity disruption, naming resolution for nodes inside the
home network for nodes in the home network are not possible. - 2: Keeping the Homenet Zone and the Public Zone equals to securely
address the connectivity disruption independence exposed in
[RFC7368] section 4.4.1 and 3.7.5. As local lookup is
possible, in case of network disruption, communications within
the home network can still rely on the DNSSEC service. Note
that outsourcing the zone signing operation does not address
connectivity disruption independence with DNSSEC. Instead a
fall back to DNS resolution occurs as the local Homenet Zone is
not signed.
- 3: Keeping the Homenet Zone and the Public Zone equals to
guarantee coherence between DNS(SEC) responses. Using a unique
zone is one way to guarantee uniqueness of the responses among
servers and places. Issues generated by different views are
discussed in more details in Section 7.
- 2: Privacy and Integrity of the DNS Zone are better guaranteed. - 2: Privacy and Integrity of the DNS Zone are better guaranteed.
When the Zone is signed by the CPE, it makes modification of When the Zone is signed by the CPE, it makes modification of
the DNS data -- for example for flow redirection -- not the DNS data -- for example for flow redirection -- not
possible. As a result, signing the Homenet Zone by the CPE possible. As a result, signing the Homenet Zone by the CPE
provides better protection for the end user privacy. provides better protection for the end user privacy.
Reasons for signing the zone by the Public Authoritative Servers are: Reasons for signing the zone by the Public Authoritative Servers are:
- 1: The CPE is not able to sign the zone, most likely because its - 1: The CPE is not able to sign the zone, most likely because its
skipping to change at page 14, line 45 skipping to change at page 15, line 23
results in a emergency key roll over. This can be mitigated results in a emergency key roll over. This can be mitigated
also by using relatively small TTLs. also by using relatively small TTLs.
- 4: Reducing configuration impacts on the end user. Unless there - 4: Reducing configuration impacts on the end user. Unless there
are some zero configuration mechanisms to provide credentials are some zero configuration mechanisms to provide credentials
between the new CPE and the Public Authoritative Name Server between the new CPE and the Public Authoritative Name Server
Sets. Authentications to Public Authoritative Name Server Set Sets. Authentications to Public Authoritative Name Server Set
should be re-configured. As CPE replacement is not expected to should be re-configured. As CPE replacement is not expected to
happen regularly, end users may not be at ease with such happen regularly, end users may not be at ease with such
configuration settings. However, mechanisms as described in configuration settings. However, mechanisms as described in
[I-D.mglt-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: Public Authoritative Servers are more likely to handle securely - 5: Public Authoritative Servers are more likely to handle securely
private keys than the CPE. However, having all private private keys than the CPE. However, having all private
information at one place may also balance that risk. information at one place may also balance that risk.
6.2. Secure Delegation 6.2. Secure Delegation
The secure delegation is set if the DS RRset is properly set in the The secure delegation is set 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 CPE or the
Public Authoritative Servers. Public Authoritative Servers.
The DS RRset can be updated manually by the CPE or the Public The DS RRset can be updated manually by the CPE or the Public
Authoritative Servers. This can be used then with nsupdate for Authoritative Servers. This can be used then with nsupdate for
example bu requires the CPE or the Public Authoritative Server to be example bu requires the CPE or the Public Authoritative Server to be
authenticated by the Parent Zone Server. Such a trust channel authenticated by the Parent Zone Server. Such a trust channel
between the CPE and the Parent Zone server may be hard to maintain, between the CPE and the Parent Zone server may be hard to maintain,
and thus may be easier to establish with the Public Authoritative and thus may be easier to establish with the Public Authoritative
Server. On the other hand, Server. On the other hand, [RFC7344] may mitigate such issues.
[I-D.ietf-dnsop-delegation-trust-maintainance] may mitigate such
issues.
7. Handling Different Views 7. Handling Different Views
The issue raised by handling different views of the DNS Homenet Zone The DNS Homenet Zone provides information about the home network and
or a DNS Homenet Zone that differs from the Public Zone is that a some user may be tempted to have different information regarding the
given DNS query may lead to different responses. The responses may origin of the DNS query. More specifically, some users may be
be different values for the queried RRsets or different RCODE or tempted to provide a different view for DNS queries originating from
different RRsets types in the responses for DNS/DNSSEC responses. the home network and for DNS queries coming from the wild Internet.
Each view can be associated to a dedicated Homenet Zone. Note that
this document does not specify how DNS queries coming from the home
network are addressed to the DNS(SEC) Homenet Zone. This could be
done via the DNS resolver hosted on the CPE for example.
The document does not recommend the CPE manages different views, This section is not normative. Section 7.1 expose different reasons
since devices may be connected to different networks at the same time that result in different views, Section 7.2 briefly describes the
or may flip / flop from one network to the other. consequences of having distinct views, and Section 7.3 provides
guidance to avoid this situation.
7.1. Motivations
The main motivation to handle different views is to provide different
information depending on the location the DNS query is emitted. Here
are a few motivations for doing so:
- 1: An end user may want to have services not published on the
Internet. Services like the CPE administration interface that
provides the GUI to administrate your CPE may not be published
on the Internet. Similarly services like the mapper that
registers the devices of your home network may not be published
on the Internet. In both case, these services should only be
known/used by the network administrator. To restrict the
access of such services, the home network administrator may
chose to publish these information only within the home
network, where it may suppose users are more trustable then on
the Internet. Even though, this assumption may not be valid,
at least, this reduces the surface of attack.
- 2: Services within the home network may be reachable using non
global IP addresses. IPv4 and NAT may be one reason. On the
other hand IPv6 may favor link-local or site-local IP
addresses. These IP addresses are not significant outside the
boundaries of the home network. As a result, they may be
published in the home network view, and should not be published
in the Internet.
- 3: If the CPE does not sign the Homenet Zone and outsource the
signing process, the two views are at least different since,
one is protected with DNSSEC whereas the other is not.
7.2. Consequences
Enabling different views leads to a non-coherent naming system.
Basically, depending on where you are some services will not be
available. This may be especially inconvenient with devices with
multiple interfaces that are attached both to the Internet via a
3G/4G interface and to the home network via a WLAN interface.
Regarding local-scope IP addresses, such device may end up with poor
connectivity. Suppose, for example, the DNS resolution is performed
via the WLAN interface attached to the CPE, the response provides
local-scope IP addresses and the communication is initiated on the
3G/4G interface. Communications with local-scope addresses will be
unreachable on the Internet, thus aborting the communication. The
same situation occurs if a device is flip / flopping between various
WLAN networks.
Regarding DNSSEC, devices with multiple interfaces will have
difficulties to secure the naming resolution as responses emitted
from the home network may not be signed.
For devices with all its interfaces attached to a single
administrative domain, that is to say the home network or the
Internet. Incoherence between DNS responses may also happen if the
device is able to perform DNS resolutions. DNS resolutions performed
via the CPE resolver may be different then those performed over the
Internet.
7.3. Guidance and Recommendations
As exposed in Section 7.2, it is recommended to avoid different
views. If network administrators chose to implement multiple views,
impacts on devices' resolution should be evaluated.
A consequence the DNS(SEC) Homenet Zone is expected to be the exact
copy of the DNS(SEC) Public Zone. As a result, services that are not
expected to be published on the Internet should not be part of the
DNS(SEC) Homenet Zone, local-scope address should not be part of the
DNS(SE) Homenet Zone, and when possible, the CPE should sign the
DNSSEC Homenet Zone.
The DNS(SEC) Homenet Zone is expected to host public information. It
is not to the DNS service to define local home networks boundaries.
Instead, local scope information is expected to be provided to the
home network using local scope naming services. mDNS [RFC6762] DNS-SD
[RFC6763] are one of these services. Currently mDNS is limited to a
single link network. However, future protocols are expected to
leverage this constraint as pointed out in
[I-D.ietf-dnssd-requirements].
8. Reverse Zone 8. Reverse Zone
Most of the description considered the DNS Homenet Zone as the non- Most of the description considered the DNS Homenet Zone as the non-
Reverse Zone. This section is focused on the Reverse Zone. Reverse Zone. This section is focused on the Reverse Zone.
First, all considerations for the DNS Homenet Zone apply to the First, all considerations for the DNS Homenet Zone apply to the
Reverse Homenet Zone. The main difference between the Reverse DNS Reverse Homenet Zone. The main difference between the Reverse DNS
Homenet Zone and the DNS Homenet Zone is that the parent zone of the Homenet Zone and the DNS Homenet Zone is that the parent zone of the
Reverse Homenet Zone is most likely managed by the ISP. As the ISP Reverse Homenet Zone is most likely managed by the ISP. As the ISP
also provides the IP prefix to the CPE, it may be able to also provides the IP prefix to the CPE, it may be able to
authenticate the CPE. If the Reverse Public Authoritative Name authenticate the CPE. If the Reverse Public Authoritative Name
Server Set is managed by the ISP, credentials to authenticate the CPE Server Set is managed by the ISP, credentials to authenticate the CPE
for the zone synchronization may be set automatically and for the zone synchronization may be set automatically and
transparently to the end user. transparently to the end user.
[I-D.mglt-homenet-naming-architecture-dhc-options] describes how [I-D.ietf-homenet-naming-architecture-dhc-options] describes how
automatic configuration may be performed. automatic configuration may be performed.
9. Security Considerations With IPv6, the domain space for IP address is so large, that reverse
zone may be confronted to a scalability issue. How to reverse zone
is generated is out of scope of this document.
[I-D.howard-dnsop-ip6rdns] provides guidance on how to address the
scalability issue.
9. Privacy Considerations
Outsourcing the DNS Authoritative service from the CPE to a third
entity comes with a a few privacy related concerns.
First the DNS Homenet Zone contains a full description of the
services hosted in the network. These services may not be expected
to be publicly shared although their names remains accessible though
the Internet. Even though DNS makes information public, the DNS does
not expect to make the complete list of service public. In fact,
making information public still requires the key (or FQDN) of each
service to be known by the resolver in order to retrieve information
of the services. More specifically, making mywebsite.example.com
public in the DNS, is not sufficient to make resolvers aware of the
existence web site.
In order to prevent the complete DN(SEC) Homenet Zone to be published
on the Internet, one should prevent AXFR queries on the Public
Authoritative Masters. Similarly, to avoid zone-walking one should
prefer NSEC3 [RFC5155] over NSEC [RFC4034].
When the DNS Homenet Zone is outsourced the end user must be aware
that it provides a complete description of the services available on
the home network. More specifically, names usually provides a clear
indication of the service and eventually the device, by as the DNS
Homenet Zone contains the IP addresses associated to the service,
they limit the scope of the scan.
In addition to the DNS Homenet Zone, the third party can also monitor
the traffic associated to the DNS Homenet Zone. This traffic may
provide indication of the services you use, how and when you use
these services. Although, cache may alter this information inside
the home network, it is likely that outside your home network this
information will not be cached.
10. 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 CPE's DNS service as a DoS attack vector.
9.1. Names are less secure than IP addresses 10.1. Names are less secure than IP addresses
This document describes how an End User can make his services and This document describes how an End User can make his services and
devices from his home network reachable on the Internet with Names devices from his home network reachable on the Internet with Names
rather than IP addresses. This exposes the home network to attackers rather than IP addresses. This exposes the home network to attackers
since names are expected to provide less randomness than IP since names are expected to provide less randomness than IP
addresses. The naming delegation protects the End User's privacy by addresses. The naming delegation protects the End User's privacy by
not providing the complete zone of the home network to the ISP. not providing the complete zone of the home network to the ISP.
However, using the DNS with names for the home network exposes the However, using the DNS with names for the home network exposes the
home network and its components to dictionary attacks. In fact, with home network and its components to dictionary attacks. In fact, with
IP addresses, the Interface Identifier is 64 bit length leading to IP addresses, the Interface Identifier is 64 bit length leading to
2^64 possibilities for a given subnetwork. This is not to mention 2^64 possibilities for a given subnetwork. This is not to mention
that the subnet prefix is also of 64 bit length, thus providing that the subnet prefix is also of 64 bit length, thus providing
another 2^64 possibilities. On the other hand, names used either for another 2^64 possibilities. On the other hand, names used either for
the home network domain or for the devices present less randomness the home network domain or for the devices present less randomness
(livebox, router, printer, nicolas, jennifer, ...) and thus exposes (livebox, router, printer, nicolas, jennifer, ...) and thus exposes
the devices to dictionary attacks. the devices to dictionary attacks.
9.2. Names are less volatile than IP addresses 10.2. Names are less volatile than IP addresses
IP addresses may be used to locate a device, a host or a Service. IP addresses may be used to locate a device, a host or a Service.
However, home networks are not expected to be assigned the same However, home networks are not expected to be assigned the same
Prefix over time. As a result observing IP addresses provides some Prefix over time. As a result observing IP addresses provides some
ephemeral information about who is accessing the service. On the ephemeral information about who is accessing the service. On the
other hand, Names are not expected to be as volatile as IP addresses. other hand, Names are not expected to be as volatile as IP addresses.
As a result, logging Names, over time, may be more valuable that As a result, logging Names, over time, may be more valuable that
logging IP addresses, especially to profile End User's logging IP addresses, especially to profile End User's
characteristics. characteristics.
PTR provides a way to bind an IP address to a Name. In that sense PTR provides a way to bind an IP address to a Name. In that sense
responding to PTR DNS queries may affect the End User's Privacy. For responding to PTR DNS queries may affect the End User's Privacy. For
that reason we recommend that End Users may choose to respond or not that reason we recommend that End Users may choose to respond or not
to PTR DNS queries and may return a NXDOMAIN response. to PTR DNS queries and may return a NXDOMAIN response.
10. IANA Considerations 11. IANA Considerations
This document has no actions for IANA. This document has no actions for IANA.
11. Acknowledgment 12. 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 CPE 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 and Michael Richardson, Ray Bellis for their feed backs on Abrahamson and Michael Richardson, Ray Bellis for their feed backs 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. outsourcing the zone signing operation outside the CPE.
12. References 13. References
12.1. Normative References 13.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987. STD 13, RFC 1034, November 1987.
[RFC1035] Mockapetris, P., "Domain names - implementation and [RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987. specification", STD 13, RFC 1035, November 1987.
[RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995,
August 1996. August 1996.
skipping to change at page 17, line 41 skipping to change at page 20, line 51
[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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2136] Vixie, P., Thomson, S., Rekhter, Y., and J. Bound, [RFC2136] Vixie, P., 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, April 1997. RFC 2136, April 1997.
[RFC2142] Crocker, D., "MAILBOX NAMES FOR COMMON SERVICES, ROLES AND [RFC2142] Crocker, D., "MAILBOX NAMES FOR COMMON SERVICES, ROLES AND
FUNCTIONS", RFC 2142, May 1997. FUNCTIONS", RFC 2142, May 1997.
[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS
NCACHE)", RFC 2308, March 1998.
[RFC2845] Vixie, P., Gudmundsson, O., Eastlake, D., and B. [RFC2845] Vixie, P., Gudmundsson, O., Eastlake, D., and B.
Wellington, "Secret Key Transaction Authentication for DNS Wellington, "Secret Key Transaction Authentication for DNS
(TSIG)", RFC 2845, May 2000. (TSIG)", RFC 2845, May 2000.
[RFC2930] Eastlake, D., "Secret Key Establishment for DNS (TKEY [RFC2930] Eastlake, D., "Secret Key Establishment for DNS (TKEY
RR)", RFC 2930, September 2000. RR)", RFC 2930, September 2000.
[RFC2931] Eastlake, D., "DNS Request and Transaction Signatures ( [RFC2931] Eastlake, D., "DNS Request and Transaction Signatures (
SIG(0)s)", RFC 2931, September 2000. SIG(0)s)", RFC 2931, September 2000.
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, March 2005.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the [RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005. Internet Protocol", RFC 4301, December 2005.
[RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
Security (DNSSEC) Hashed Authenticated Denial of
Existence", RFC 5155, March 2008.
[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, August 2008. (TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5936] Lewis, E. and A. Hoenes, "DNS Zone Transfer Protocol [RFC5936] Lewis, E. and A. Hoenes, "DNS Zone Transfer Protocol
(AXFR)", RFC 5936, June 2010. (AXFR)", RFC 5936, June 2010.
[RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
"Internet Key Exchange Protocol Version 2 (IKEv2)", RFC
5996, September 2010.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, January 2012. Security Version 1.2", RFC 6347, January 2012.
[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, July 2012. DHCPv6 Reconfigure Messages", RFC 6644, July 2012.
[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, [RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
February 2013. February 2013.
12.2. Informational References [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, February 2013.
[I-D.ietf-dnsop-delegation-trust-maintainance] [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kumari, W., Gudmundsson, O., and G. Barwood, "Automating Kivinen, "Internet Key Exchange Protocol Version 2
DNSSEC Delegation Trust Maintenance", draft-ietf-dnsop- (IKEv2)", STD 79, RFC 7296, October 2014.
delegation-trust-maintainance-14 (work in progress), June
2014.
[I-D.ietf-homenet-arch] 13.2. Informational References
Chown, T., Arkko, J., Brandt, A., Troan, O., and J. Weil,
"IPv6 Home Networking Architecture Principles", draft-
ietf-homenet-arch-16 (work in progress), June 2014.
[I-D.mglt-homenet-naming-architecture-dhc-options] [I-D.howard-dnsop-ip6rdns]
Howard, L., "Reverse DNS in IPv6 for Internet Service
Providers", draft-howard-dnsop-ip6rdns-00 (work in
progress), June 2014.
[I-D.ietf-dnssd-requirements]
Lynn, K., Cheshire, S., Blanchet, M., and D. Migault,
"Requirements for Scalable DNS-SD/mDNS Extensions", draft-
ietf-dnssd-requirements-04 (work in progress), October
2014.
[I-D.ietf-homenet-naming-architecture-dhc-options]
Migault, D., Cloetens, W., Griffiths, C., and R. Weber, Migault, D., Cloetens, W., Griffiths, C., and R. Weber,
"DHCP Options for Homenet Naming Architecture", draft- "DHCP Options for Homenet Naming Architecture", draft-
mglt-homenet-naming-architecture-dhc-options-02 (work in ietf-homenet-naming-architecture-dhc-options-00 (work in
progress), July 2014. progress), September 2014.
[RFC1033] Lottor, M., "Domain administrators operations guide", RFC [RFC1033] Lottor, M., "Domain administrators operations guide", RFC
1033, November 1987. 1033, November 1987.
[RFC7344] Kumari, W., Gudmundsson, O., and G. Barwood, "Automating
DNSSEC Delegation Trust Maintenance", RFC 7344, September
2014.
[RFC7368] Chown, T., Arkko, J., Brandt, A., Troan, O., and J. Weil,
"IPv6 Home Networking Architecture Principles", RFC 7368,
October 2014.
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]
-05:
*Clarifying on handling different views:
- 1: How the CPE may be involved in the resolution and responds
without necessarily requesting the Public Masters (and
eventually the Hidden Master)
- 2: How to handle local scope resolution that is link-local, site-
local and NAT IP addresses as well as Private domain names that
the administrator does not want to publish outside the home
network.
Adding a Privacy Considerations Section
Clarification on pro/cons outsourcing zone-signing
Documenting how to handle reverse zones
Adding reference to RFC 2308
-04: -04:
*Clarifications on zone signing *Clarifications on zone signing
*Rewording *Rewording
*Adding section on different views *Adding section on different views
*architecture clarifications *architecture clarifications
skipping to change at page 20, line 38 skipping to change at page 24, line 38
Server. Server.
* For next version, address functions of MDNS within Homenet Lan and * For next version, address functions of MDNS within Homenet Lan and
publishing details northbound via Hidden Master. publishing details northbound via Hidden Master.
-00: First version published. -00: First version published.
Authors' Addresses Authors' Addresses
Daniel Migault Daniel Migault
Orange Ericsson
38 rue du General Leclerc 8400 boulevard Decarie
92794 Issy-les-Moulineaux Cedex 9 Montreal, QC H4P 2N2
France Canada
Phone: +33 1 45 29 60 52 Email: mglt.ietf@gmail.com
Email: daniel.migault@orange.com
Wouter Cloetens Wouter Cloetens
SoftAtHome SoftAtHome
vaartdijk 3 701 vaartdijk 3 701
3018 Wijgmaal 3018 Wijgmaal
Belgium Belgium
Email: wouter.cloetens@softathome.com Email: wouter.cloetens@softathome.com
Chris Griffiths Chris Griffiths
Dyn Dyn
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