| HOMENET | D. Migault (Ed) |
| Internet-Draft | Ericsson |
| Intended status: Standards Track | T. Mrugalski |
| Expires: April 21, 2016 | ISC |
| C. Griffiths | |
| R. Weber | |
| Nominum | |
| W. Cloetens | |
| SoftAtHome | |
| October 19, 2015 |
DHCPv6 Options for Homenet Naming Architecture
draft-ietf-homenet-naming-architecture-dhc-options-03.txt
Customer Premises Equipment (CPE) devices are usually constrained devices with reduced network and CPU capabilities. As such, a CPE exposing the authoritative naming service for its home network on the Internet may become vulnerable to resource exhaustion attacks. One way to avoid exposing CPE is to outsource the authoritative service to a third party, e.g. ISP. Such an outsource requires setting up an architecture which may be inappropriate for most end users. This document defines DHCPv6 options so any agnostic CPE can automatically proceed to the appropriate configuration and outsource the authoritative naming service for the home network. In most cases, the outsourcing mechanism is transparent for the end user.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 21, 2016.
Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
The reader is expected to be familiar with [I-D.ietf-homenet-front-end-naming-delegation] and its terminology section. This section defines terms that have not been defined in [I-D.ietf-homenet-front-end-naming-delegation]:
CPEs are usually constrained devices with reduced network and CPU capacities. As such, a CPE hosting on the Internet the authoritative naming service for its home network may become vulnerable to resource exhaustion attacks. Outsourcing the authoritative service to a third party avoids exposing the CPE to such attacks. This third party can be the ISP or any other independent third party.
Outsourcing the authoritative naming service to a third party requires setting up an architecture designated in this document as the Outsourcing Infrastructure. These settings may be inappropriate for most end users that do not have the sufficient knowledge. To address this issue, this document proposes DHCPv6 options so any agnostic CPE can automatically set the Outsourcing Infrastructure. In most cases, these DHCPv6 options are sufficient and do not require any additional interaction from the end user, thus achieving a zero-config settings. In some other cases, the end user is expected to perform some limited manual configuration.
When the CPE is plugged, the DHCPv6 options described in the document enable:
The DHCPv6 options described in this document make possible to configure an Outsourcing Infrastructure with no or little configurations from the end user. A zero-config setting is achieved if the the link between the CPE and the DHCPv6 server and the link between the DHCPv6 server and the various DNS servers (Homenet Zone Server, the Reverse Synchronization Server, Synchronization Server) are trusted. For example, one way to provide a thrustworhy connection between the CPE and the DHCPv6 server is defined in [I-D.ietf-dhc-sedhcpv6]. When both links are trusted, the CPE is able to provide its authentication credentials (a Client Public Key) to the DHCPv6 server, that in turn forwards it to the various DNS servers. With the authentication credentials on the DNS servers, the CPE is able to securely update.
If the DHCPv6 server cannot provide the Client Public Key to one of these servers (most likely the Synchronization Server) and the CPE needs to interact with the server, then, the end user is expected to provide the CPE's Client Public Key to these servers (the Reverse Synchronization Server or the Synchronization Server) either manually or using other mechanisms. Such mechanisms are outside the scope of this document. In that case, the authentication credentials need to be provided every time the key is modified. Appendix A provides more details on how different scenarios impact the end users.
The remaining of this document is structured as follows. Section 4 provides an overview of the DHCPv6 options as well as the expected interactions between the CPE and the various involved entities. This section also provides an overview of available mechanisms to secure DNS transactions and update DNS data. Section 5 describes how the CPE may securely synchronize and update DNS data. Section 6 describes the payload of the DHCPv6 options and Section 7 details how DHCPv6 client, server and relay agent behave. Section 8 lists the new parameters to be registered at the IANA, Section 9 provides security considerations. Finally, Appendix A describes how the CPE may behave and be configured regarding various scenarios.
This section provides an overview of the CPE's interactions with the Outsourcing Infrastructure in Section 4.1, and so the necessary for its setting. In this document, the configuration is provided via DHCPv6 options. Once configured, the CPE is expected to be able to update and publish DNS data on the different components of the Outsourcing Infrastructure. As a result authenticating and updating mechanisms play an important role in the specification. Section 4.2 provides an overview of the different authentication methods and Section 4.3 provides an overview of the different update mechanisms considered to update the DNS data.
This section illustrates how a CPE receives the necessary information via DHCPv6 options to outsource its authoritative naming service on the Outsourcing Infrastructure. For the sake of simplicity, this section assumes that the DHCPv6 server is able to communicate to the various DNS servers and to provide them the public key associated with the CPE. Once each server got the public key, the CPE can proceed to transactions in an authenticated and secure way.
This scenario has been chosen as it is believed to be the most popular scenario. This document does not ignore that scenarios where the DHCP Server does not have privileged relations with the Synchronization Server must be considered. These cases are discussed latter in Appendix A. Such scenario does not necessarily require configuration for the end user and can also be zero-config.
The scenario is represented in Figure 1.
+---------------------+
| DHCPv6 Server |
+---------------------+
^ ^ ^
| | |
1.| |3. |2.
| | |
v v |
+------+ | +--------------------------------+
| | 4. +--->| DNS Template Server |
| |<---------->| |
| | | +--------------------------------+
| CPE | |
| | | +--------------------------------+
| | 5./6. +--->| Reverse Synchronization |
| |<---------->| Server |
| | | +--------------------------------+
| | |
| | | +--------------------------------+
+------+ +--->| Synchronization Server |
| |
+--------------------------------+
Figure 1: Protocol Overview
As described above, the CPE is likely to interact with various DNS content. More specifically, the CPE is likely to update the:
Step 2 and step 3 should be considered as independent steps and could be re-ordered. In fact, the DHCPv6 server does not have to wait for a confirmation from the DNS servers the Client Public Key has been properly received, and is operational by the DNS servers. The DHCP Server is expected to reply upon receiving the Client Public Key Option. The reply to the message with a Client Public Key Option from the DHCP Server is interpreted by the DHCPv6 client as a confirmation of the reception of the option by the DHCP Server only. It does not indicate whether the server had processed the option or not. Debugging configurations errors or transmission error with one of the DNS servers is let to the CPE and thus is outside of the scope of the DHCPv6. First, it is unlikely a DNS server can validate that the Client Public Key will be operational for the CPE, as multiple causes of errors could occur. For example, the Client Public Key may have been changed during the transmission or by the DHCP Server, or the DNS server may be misconfigured. Second, the number of error codes would be too complex. In addition to multiple causes of errors, multiple architectures and multiple DNS servers may be involved. Third, this may cause significant DHCP Server performance degradation.
In fact, the CPE performs these updates in a secure manner. There are multiple ways to secure a DNS transaction and this document considers two mechanisms: nsupdate and primary/secondary synchronization. Section 4.2 describes the authentication method that may be use to secure the DNS transactions of the CPE. The appropriate authentication methods may, for example, be chosen according to the level of confidentiality or the level of authentication requested by the CPE transactions. Section 4.3 positions the nsupdate and primary/secondary synchronization mechanisms. The update appropriate update mechanism may depend on the for example on the update frequency or the size of the DNS data to update.
Multiple protocols like IPsec [RFC4301] or TLS / DTLS [RFC5246] / [RFC6347] may be used to secure DNS transactions between the CPE and the DNS servers. This document limits its scope to authentication method that have been designed specifically for DNS. This includes DNSSEC [RFC4033], [RFC4034], [RFC4035] that authenticates and provides integrity protection of DNS data, TSIG [RFC2845], [RFC2930] that use a shared secret to secure a transaction between two end points and SIG(0) [RFC2931] authenticates the DNS packet exchanged.
The key issue with TSIG is that a shared secret must be negotiated between the CPE and the server. On the other hand, TSIG performs symmetric cryptography which is light in comparison with asymmetric cryptography used by SIG(0). As a result, over large zone transfer, TSIG may be preferred to SIG(0).
This document does not provide means to distribute shared secret for example using a specific DHCPv6 option. The only assumption made is that the CPE generates or is assigned a public key.
As a result, when the document specifies the transaction is secured with TSIG, it means that either the CPE and the DNS server have been manually configured with a shared secret, or the shared secret has been negotiated using TKEY [RFC2930], and the TKEY exchanged are secured with SIG(0).
Exchanges with the DNS Template Server to retrieve the Homenet Zone Template may be protected by SIG(0), TSIG or DNSSEC. When DNSSEC is used, it means the DNS Template Server only provides integrity protection, and does not necessarily prevent someone else to query the Homenet Zone Template. In addition, DNSSEC is only a way to protect the AXFR queries transaction, in other words, DNSSEC cannot be used to secure updates. If DNSSEC is used to provide integrity protection for the AXFR response, the CPE should proceed to the DNSSEC signature checks. If signature check fails, it MUST reject the response. If the signature check succeeds, the CPE removes all DNSSEC related RRsets (DNSKEY, RRSIG, NSEC* ...) before building the Homenet Zone. In fact, these DNSSEC related fields are associated to the Homenet Zone Template and not the Homenet Zone.
Any update exchange should use SIG(0) or TSIG to authenticate the exchange.
As updates only concern DNS zones, this document only considers DNS update mechanisms such as DNS update [RFC2136] [RFC3007] or a primary / secondary synchronization.
The Homenet Zone Template SHOULD be updated with DNS update as it contains static configuration data that is not expected to evolve over time.
The Homenet Reverse Zone and the Homenet Zone can be updated either with DNS update or using a primary / secondary synchronization. As these zones may be large, with frequent updates, we recommend to use the primary / secondary architecture as described in [I-D.ietf-homenet-front-end-naming-delegation]. The primary / secondary mechanism is preferred as it better scales and avoids DoS attacks: First the primary notifies the secondary the zone must be updated, and leaves the secondary to proceed to the update when possible. Then, the NOTIFY message sent by the primary is a small packet that is less likely to load the secondary. At last, the AXFR query performed by the secondary is a small packet sent over TCP (section 4.2 [RFC5936]) which makes unlikely the secondary to perform reflection attacks with a forged NOTIFY. On the other hand, DNS updates can use UDP, packets require more processing than a NOTIFY, and they do not provide the server the opportunity to postpone the update.
The primary / secondary architecture is described in [I-D.ietf-homenet-front-end-naming-delegation]. The CPE hosts a Hidden Primary that synchronizes with a Synchronization Server or the Reverse Synchronization Server.
When the CPE is plugged its IP address may be unknown to the secondary. The section details how the CPE or primary communicates the necessary information to set up the secondary.
In order to set the primary / secondary configuration, both primary and secondaries must agree on 1) the zone to be synchronized, 2) the IP address and ports used by both primary and secondary.
The CPE is aware of the zone to be synchronized by reading the Registered Homenet Domain in the Homenet Zone Template provided by the Zone Template Option (OPTION_DNS_ZONE_TEMPLATE). The IP address of the secondary is provided by the Synchronization Server Option (OPTION_SYNC_SERVER).
The Synchronization Server has been configured with the Registered Homenet Domain and the Client Public Key that identifies the CPE. The only missing information is the IP address of the CPE. This IP address is provided by the CPE by sending a NOTIFY [RFC1996].
When the CPE has built its Homenet Zone, it sends a NOTIFY message to the Synchronization Servers. Upon receiving the NOTIFY message, the secondary reads the Registered Homenet Domain and checks the NOTIFY is sent by the authorized primary. This can be done using the shared secret (TSIG) or the public key (SIG(0)). Once the NOTIFY has been authenticated, the Synchronization Servers might consider the source IP address of the NOTIFY query to configure the primaries attributes.
The CPE is aware of the zone to be synchronized by looking at its assigned prefix. The IP address of the secondary is provided by the Reverse Synchronization Server Option (OPTION_REVERSE_SYNC_SERVER).
Configuration of the secondary is performed as illustrated in Section 5.1.1.
The Homenet Zone Template contains at least the related fields of the Public Authoritative Server(s) as well as the Homenet Registered Domain, that is SOA, and NS fields. This template might be generated automatically by the owner of the DHCP Server. For example, an ISP might provide a default Homenet Registered Domain as well as default Public Authoritative Server(s). This default settings should provide the CPE the necessary pieces of information to set the homenet naming architecture.
If the Homenet Zone Template is not subject to modifications or updates, the owner of the template might only use DNSSEC to enable integrity check.
On the other hand, the Homenet Zone Template might also be subject to modification by the CPE. The advantage of using the standard DNS zone format is that standard DNS update mechanism can be used to perform updates. These updates might be accepted or rejected by the owner of the Homenet Zone Template. Policies that defines what is accepted or rejected is out of scope of this document. However, this document assumes the Registered Homenet Domain is used as an index by the Synchronization Server, and SIG(0), TSIG are used to authenticate the CPE. As a result, the Registered Homenet Domain should not be modified unless the Synchronization Server can handle with it.
The Homenet Zone might be generated from the Homenet Zone Template. How the Homenet Zone is generated is out of scope of this document. In some cases, the Homenet Zone might be the exact copy of the Homenet Zone Template. In other cases, it might be generated from the Homenet Zone Template with additional RRsets. In some other cases, the Homenet Zone might be generated without considering the Homenet Zone Template, but only considering specific configuration rules.
In the current document the CPE only sets a single zone that is associated with one single Homenet Registered Domain. The domain might be assigned by the owner of the Homenet Zone Template. This constraint does not prevent the CPE to use multiple domain names. How additional domains are considered is out of scope of this document. One way to handle these additional zones is to configure static redirections to the Homenet Zone using CNAME [RFC2181], [RFC1034], DNAME [RFC6672] or CNAME+DNAME [I-D.sury-dnsext-cname-dname].
This section details the payload of the DHCPv6 options. A few DHCPv6 options are used to advertise a server the CPE may be expected to interact with. Interaction may require to define update and authentication methods. Update fields are shared by multiple DHCPv6 options and are described in separate sections. Section 6.1 describes the Supported Authentication Method field, Section 6.2 describes the Update field, the remaining Section 6.3, Section 6.4, Section 6.5, Section 6.6 describe the DHCPv6 options.
The Supported Authentication Methods field of the DHCPv6 option represented in Figure 2 indicates the authentication method supported by the DNS server. One of these mechanism MUST be chosen by the CPE in order to perform a transaction with the DNS server. See Section 4.2 for more details.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Supported Auth. Methods |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Supported Authentication Methods Filed
A Supported Authentication Methods field with all bits set to zero indicates the operation is not permitted. The Supported Authentication Methods field may be set to zero when updates operations are not permitted for the DNS Homenet Template. In any other case this is an error.
The Update Field of the DHCPv6 option is represented in Figure 3. It indicates the update mechanism supported by the DNS server. See Section 4.3 for more details.
0
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| Update |
+-+-+-+-+-+-+-+-+
Figure 3: Update Field
The Client Public Key Option (OPTION_PUBLIC_KEY) indicates the Client Public Key that is used to authenticate the CPE. This option is defined in [I-D.ietf-dhc-sedhcpv6].
The Zone Template Option (OPTION_DNS_ZONE_TEMPLATE) Option indicates the CPE how to retrieve the Homenet Zone Template. It provides a FQDN the CPE SHOULD query with a DNS query of type AXFR as well as the authentication methods associated to the AXFR query or the nsupdate queries. Homenet Zone Template update, if permitted MUST use the DNS Update mechanism.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_DNS_ZONE_TEMPLATE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Supp. Auth. Methods (axfr) | Supp. Auth. Methods (update) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ Zone Template FQDN /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Zone Template Option
The Synchronization Server Option (OPTION_SYNC_SERVER) provides information necessary for the CPE to upload the Homenet Zone to the Synchronization Server. Finally, the option provides the authentication methods that are available to perform the upload. The upload is performed via a DNS primary / secondary architecture or DNS updates.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_SYNC_SERVER | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Supported Auth. Methods | Update | Server /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Port | |
+-+-+-+-+-+-+-+-+ |
| |
/ Synchronization Server FQDN /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Synchronization Server Option
The Reverse Synchronization Server Option (OPTION_REVERSE_SYNC_SERVER) provides information necessary for the CPE to upload the Homenet Zone to the Synchronization Server. The option provides the authentication methods that are available to perform the upload. The upload is performed via a DNS primary / secondary architecture or DNS updates.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_REVERSE_SYNC_SERVER | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Supported Auth. Methods | Update | Server /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Port | |
+-+-+-+-+-+-+-+-+-+ |
| |
/ Reverse Synchronization Server FQDN /
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Reverse Synchronization Server Option
Sections 17.2.2 and 18.2 of [RFC3315] govern server operation in regards to option assignment. As a convenience to the reader, we mention here that the server will send option foo only if configured with specific values for foo and if the client requested it. In particular, when configured the DHCP Server sends the Zone Template Option, Synchronization Server Option, Reverse Synchronization Server Option when requested by the DHCPv6 client by including necessary option codes in its ORO.
The DHCP Server may receive a Client Public Key Option (OPTION_PUBLIC_KEY) from the CPE. Upon receipt of this DHCPv6 option, the DHCP Server SHOULD acknowledge the reception of the Client Public Key Option as described in Section 4.1 and communicate this credential to the available DNS Servers like the DNS Template Server, the Synchronization Server and the Reverse Synchronization Server, unless not configured to do so.
A CPE may update its Client Public Key by sending a new value in the Client Public Key Option (OPTION_PUBLIC_KEY) as this document assumes the link between the CPE and the DHCP Server is considered authenticated and trusted. The server SHOULD process received Client Public Key Option sent by the client (see step 2 in Section 4.1), unless not configured to do so.
The DHCPv6 client SHOULD send a Client Public Key Option (OPTION_PUBLIC_KEY) to the DHCP Server. This Client Public Key authenticates the CPE.
The DHCPv6 client sends a ORO with the necessary option codes: Zone Template Option, Synchronization Server Option and Reverse Synchronization Server Option.
Upon receiving a DHCP option described in this document in the Reply message, the CPE SHOULD retrieve or update DNS zones using the associated Supported Authentication Methods and update protocols, as described in Section 5.
There are no additional requirements for the DHCP Relay agents.
The DHCP options detailed in this document is:
It is recommended that the (Reverse) Homenet Zone is signed with DNSSEC. The zone may be signed by the CPE or by a third party. We recommend the zone to be signed by the CPE, and that the signed zone is uploaded.
The channel MUST be secured because the CPE provides authentication credentials. Unsecured channel may result in CPE impersonation attacks.
The document considers that the channel between the CPE and the ISP DHCP Server is trusted. More specifically, the CPE is authenticated and the exchanged messages are protected. The current document does not specify how to secure the channel. [RFC3315] proposes a DHCP authentication and message exchange protection, [RFC4301], [RFC7296] propose to secure the channel at the IP layer.
CPE have not been designed for handling heavy load. The CPE are exposed on the Internet, and their IP address is publicly published on the Internet via the DNS. This makes the Home Network sensitive to Deny of Service Attacks. The resulting outsourcing architecture is described in [I-D.ietf-homenet-front-end-naming-delegation]. This document shows how the outsourcing architecture can be automatically set.
We would like to thank Marcin Siodelski and Bernie Volz for their comments on the design of the DHCPv6 options. We would also like to thank Mark Andrews, Andrew Sullivan and Lorenzo Colliti for their remarks on the architecture design. The designed solution has been largely been inspired by Mark Andrews's document [I-D.andrews-dnsop-pd-reverse] as well as discussions with Mark. We also thank Ray Hunter for its reviews, its comments and for suggesting an appropriated terminology.
| [I-D.andrews-dnsop-pd-reverse] | Andrews, M., "Automated Delegation of IP6.ARPA reverse zones with Prefix Delegation", Internet-Draft draft-andrews-dnsop-pd-reverse-02, November 2013. |
| [I-D.ietf-dhc-sedhcpv6] | Jiang, S., Shen, S., Zhang, D. and T. Jinmei, "Secure DHCPv6", Internet-Draft draft-ietf-dhc-sedhcpv6-08, June 2015. |
| [I-D.ietf-homenet-front-end-naming-delegation] | Migault, D., Weber, R., Hunter, R., Griffiths, C. and W. Cloetens, "Outsourcing Home Network Authoritative Naming Service", Internet-Draft draft-ietf-homenet-front-end-naming-delegation-04, September 2015. |
| [I-D.sury-dnsext-cname-dname] | Sury, O., "CNAME+DNAME Name Redirection", Internet-Draft draft-sury-dnsext-cname-dname-00, April 2010. |
This section details various scenarios and discuss their impact on the end user.
The base scenario is the one described in Section 4. It is typically the one of an ISP that manages the DHCP Server, and all DNS servers.
The end user subscribes to the ISP (foo), and at subscription time registers for example.foo as its Registered Homenet Domain example.foo. Since the ISP knows the Registered Homenet Domain and the Public Authoritative Server(s) the ISP is able to build the Homenet Zone Template.
The ISP manages the DNS Template Server, so it is able to load the Homenet Zone Template on the DNS Template Server.
When the CPE is plugged (at least the first time), it provides its Client Public Key to the DHCP Server. In this scenario, the DHCP Server and the DNS Servers are managed by the ISP so the DHCP Server can provide authentication credentials of the CPE to enable secure authenticated transaction between the CPE and these DNS servers. More specifically, credentials are provided to:
The CPE can update the zone using DNS update or a primary / secondary configuration in a secure way.
The main advantage of this scenario is that the naming architecture is configured automatically and transparently for the end user.
The drawbacks are that the end user uses a Registered Homenet Domain managed by the ISP and that it relies on the ISP naming infrastructure.
This section considers the case when the end user wants its home network to use example.com as a Registered Homenet Domain instead of example.foo that has been assigned by the ISP. We also suppose that example.com is not managed by the ISP.
This can also be achieved without any configuration. When the end user buys the domain name example.com, it may request to redirect the name example.com to example.foo using static redirection with CNAME [RFC2181], [RFC1034], DNAME [RFC6672] or CNAME+DNAME [I-D.sury-dnsext-cname-dname].
This configuration is performed once when the domain name example.com is registered. The only information the end user needs to know is the domain name assigned by the ISP. Once this configuration is done no additional configuration is needed anymore. More specifically, the CPE may be changed, the zone can be updated as in Appendix A.1 without any additional configuration from the end user.
The main advantage of this scenario is that the end user benefits from the Zero Configuration of the Base Scenario Appendix A.1. Then, the end user is able to register for its home network an unlimited number of domain names provided by an unlimited number of different third party providers.
The drawback of this scenario may be that the end user still rely on the ISP naming infrastructure. Note that the only case this may be inconvenient is when the DNS Servers provided by the ISPs results in high latency.
This scenario considers that the end user uses example.com as a Registered Homenet Domain, and does not want to rely on the authoritative servers provided by the ISP.
In this section we limit the outsourcing to the Synchronization Server and Public Authoritative Server(s) to a third party. All other DNS Servers DNS Template Server, Reverse Public Authoritative Server(s) and Reverse Synchronization Server remain managed by the ISP. The reason we consider that Reverse Public Authoritative Server(s) and Reverse Synchronization Server remains managed by the ISP are that the prefix is managed by the ISP, so outsourcing these resources requires some redirection agreement with the ISP. More specifically the ISP will need to configure the redirection on one of its Reverse DNS Servers. That said, outsourcing these resources is similar as outsourcing Synchronization Server and Public Authoritative Server(s) to a third party. Similarly, the DNS Template Server can be easily outsourced as detailed in this section
Outsourcing Synchronization Server and Public Authoritative Server(s) requires:
The main advantage of this scenario is that the DNS infrastructure is completely outsourced to the third party. Most likely the Client Public Key that authenticate the CPE need to be configured for every CPE. Configuration is expected to be CPE live-long.
This scenario considers a CPE connected to multiple ISPs.
Firstly, suppose the CPE has been configured with the based scenarios exposed in Appendix A.1. The CPE has multiple interfaces, one for each ISP, and each of these interface is configured using DHCP. The CPE sends to each ISP its Client Public Key Option as well as a request for a Zone Template Option, a Synchronization Server Option and a Reverse Synchronization Server Option. Each ISP provides the requested DHCP options, with different values. Note that this scenario assumes, the home network has a different Registered Homenet Domain for each ISP as it is managed by the ISP. On the other hand, the CPE Client Public Key may be shared between the CPE and the multiple ISPs. The CPE builds the associate DNS(SEC) Homenet Zone, and proceeds to the various settings as described in Appendix A.1.
The protocol and DHCPv6 options described in this document are fully compatible with a CPE connected to multiple ISPs with multiple Registered Homenet Domains. However, the CPE should be able to handle different Registered Homenet Domains. This is an implementation issue which is outside the scope of the current document. More specifically, multiple Registered Homenet Domains leads to multiple DNS(SEC) Homenet Zones. A basic implementation may erase the DNS(SEC) Homenet Zone that exists when it receives DHCPv6 options, and rebuild everything from scratch. This will work for an initial configuration but comes with a few drawbacks. First, updates to the DNS(SEC) Homenet Zone may only push to one of the multiple Registered Homenet Domain, the latest Registered Homenet Domain that has been set, and this is most likely expected to be almost randomly chosen as it may depend on the latency on each ISP network at the boot time. As a results, this leads to unsynchronized Registered Homenet Domains. Secondly, if the CPE handles in some ways resolution, only the latest Registered Homenet Domain set may be able to provide naming resolution in case of network disruption.
Secondly, suppose the CPE is connected to multiple ISP with a single Registered Homenet Domain. In this case, the one party is chosen to host the Registered Homenet Domain. This entity may be one of the ISP or a third party. Note that having multiple ISPs can be motivated for bandwidth aggregation, or connectivity fail-over. In the case of connectivity fail-over, the fail-over concerns the access network and a failure of the access network may not impact the core network where the Synchronization Server and Public Authoritative Primaries are hosted. In that sense, choosing one of the ISP even in a scenario of multiple ISPs may make sense. However, for sake of simplicity, this scenario assumes that a third party has be chosen to host the Registered Homenet Domain. The DNS settings for each ISP is described in Appendix A.2 and Appendix A.3. With the configuration described in Appendix A.2, the CPE is expect to be able to handle multiple Homenet Registered Domain, as the third party redirect to one of the ISPs Servers. With the configuration described in Appendix A.3, DNS zone are hosted and maintained by the third party. A single DNS(SEC) Homenet Zone is built and maintained by the CPE. This latter configuration is likely to match most CPE implementations.
The protocol and DHCPv6 options described in this document are fully compatible with a CPE connected to multiple ISPs. To configure or not and how to configure the CPE depends on the CPE facilities. Appendix A.1 and Appendix A.2 require the CPE to handle multiple Registered Homenet Domain, whereas Appendix A.3 does not have such requirement.
[RFC Editor: This section is to be removed before publication]
-05: changing Master to Primary, Slave to Secondary
-04: Working Version Major modifications are:
-03: Working Version Major modifications are:
-02: Working Version Major modifications are:
-01: Working Version Major modifications are:
-00: version published in the homenet WG. Major modifications are:
-00: First version published in dhc WG.