Network Working Group W.D. Dec, Ed. Internet-Draft Cisco Systems, Inc. Intended status: Standards Track B.S. Sarikaya Expires: April 20, 2013 Huawei USA G.Z. Zorn Network Zen D.M. Miles Google B.L. Lourdelet October 19, 2012 RADIUS attributes for IPv6 Access Networks draft-ietf-radext-ipv6-access-13 Abstract This document specifies additional IPv6 RADIUS attributes useful in residential broadband network deployments. The attributes, which are used for authorization and accounting, enable assignment of a host IPv6 address and IPv6 DNS server address via DHCPv6; assignment of an IPv6 route announced via router advertisement; assignment of a named IPv6 delegated prefix pool; and assignment of a named IPv6 pool for host DHCPv6 addressing. Requirements Language 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 RFC 2119 [RFC2119]. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on April 20, 2013. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the Dec, et al. Expires April 20, 2013 [Page 1] Internet-Draft RADIUS IPv6 Access October 2012 document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Deployment Scenarios . . . . . . . . . . . . . . . . . . . . . 3 2.1. IPv6 Address Assignment . . . . . . . . . . . . . . . . . 3 2.2. DNS Servers . . . . . . . . . . . . . . . . . . . . . . . 4 2.3. IPv6 Route Information . . . . . . . . . . . . . . . . . . 4 2.4. Delegated IPv6 Prefix Pool . . . . . . . . . . . . . . . . 5 2.5. Stateful IPv6 address pool . . . . . . . . . . . . . . . . 5 3. Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Framed-IPv6-Address . . . . . . . . . . . . . . . . . . . 5 3.2. DNS-Server-IPv6-Address . . . . . . . . . . . . . . . . . 6 3.3. Route-IPv6-Information . . . . . . . . . . . . . . . . . . 7 3.4. Delegated-IPv6-Prefix-Pool . . . . . . . . . . . . . . . . 8 3.5. Stateful-IPv6-Address-Pool . . . . . . . . . . . . . . . . 9 3.6. Table of attributes . . . . . . . . . . . . . . . . . . . 9 4. Diameter Considerations . . . . . . . . . . . . . . . . . . . 10 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 8.1. Normative References . . . . . . . . . . . . . . . . . . . 11 8.2. Informative References . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 1. Introduction This document specifies additional RADIUS attributes used to support configuration of DHCPv6 and/or ICMPv6 Router Advertisement (RA) parameters on a per-user basis. The attributes, which complement those defined in [RFC3162] and [RFC4818], support the following: o Assignment of specific IPv6 addresses to hosts via DHCPv6. o Assignment of an IPv6 DNS server address, via DHCPv6 or Router Advertisement [RFC6106]. o Configuration of more specific routes to be announced to the user via the Route Information Option defined in [RFC4191] Section 2.3. o The assignment of a named delegated prefix pool for use with "IPv6 Prefix Options for DHCPv6" [RFC3633]. Dec, et al. Expires April 20, 2013 [Page 2] Internet-Draft RADIUS IPv6 Access October 2012 o The assignment of a named stateful address pool for use with DHCPv6 stateful address assignment [RFC3315]. 2. Deployment Scenarios The extensions in this draft are intended to be applicable across a wide variety of network access scenarios where Radius is involved. One such typical network scenario is illustrated in Figure 1. It is composed of a IP Routing Residential Gateway (RG) or host, a Layer 2 Access-Node (AN) e.g. a Digital Subscriber Line Access Multiplexer - DSLAM, an IP Network Access Servers (NASes), and an Authentication Authorization & Accounting (AAA) server. +-----+ | AAA | | | +--+--+ ^ . .(Radius) . v +------+ +---+---+ +------+ | AN | | NAS | | RG/ +-------| +-----------+----------+ | | host | | | | | +------+ (DSL) +------+ (Ethernet) +-------+ Figure 1 In the depicted scenario the NAS may embed a IP addressing protocols (e.g. a DHCPv6 server) to handle address assignment to RGs/hosts. The RADIUS server authenticates each RG/host and returns to the attributes used for authorization and accounting. These attributes can include a host's IPv6 address, a DNS server address and a set of IPv6 routes to be advertised via DHCPv6 or ICMPv6. The name of a prefix pool to be used for DHCPv6 Prefix Delegation, or the name of an address pool to be used for DHCPv6 address assignment can also be attributes provided to the NAS by the RADIUS AAA server. The following sub-sections discuss how these attributes are used in more detail. Dec, et al. Expires April 20, 2013 [Page 3] Internet-Draft RADIUS IPv6 Access October 2012 2.1. IPv6 Address Assignment DHCPv6 [RFC3315] provides a mechanism to assign one or more non- temporary IPv6 addresses to hosts. To provide a DHCPv6 server residing on a NAS with one or more IPv6 addresses to be assigned, this document specifies the Framed-IPv6-Address Attribute. While [RFC3162] permits an IPv6 address to be specified via the combination of the Framed-Interface-Id and Framed-IPv6-Prefix attributes, this separation is more natural for use with PPP's IPv6 Control Protocol than it is for use with DHCPv6, and the use of a single IPv6 address attribute makes for easier processing of accounting records. Since DHCPv6 can be deployed on the same network as ICMPv6 stateless (SLAAC) [RFC4862], it is possible that the NAS will require both stateful and stateless configuration information. Therefore it is possible for the Framed-IPv6-Address, Framed-IPv6-Prefix and Framed- Interface-Id attributes [RFC3162] to be included within the same packet. To avoid ambiguity, the Framed-IPv6-Address attribute is only used for authorization and accounting of DHCPv6-assigned addresses and the Framed-IPv6-Prefix and Framed-Interface-Id attributes are used for authorization and accounting of addresses assigned via SLAAC. 2.2. DNS Servers DHCPv6 provides an option for configuring a host with the IPv6 address of a DNS server. The IPv6 address of a DNS server can also be conveyed to the host using ICMPv6 with Router Advertisements, via the [RFC6106] option. To provide the NAS with the IPv6 address of a DNS server, this document specifies the DNS-Server-IPv6-Address Attribute. 2.3. IPv6 Route Information An IPv6 Route Information option, defined in [RFC4191] is intended to be used to inform a host connected to the NAS that a specific route is reachable via any given NAS. This document specifies the RADIUS attribute that allows the AAA server to provision the announcement by the NAS of a specific Route Information Option to an accessing host. The NAS may advertise this route using the method defined in [RFC4191], or using other equivalent methods. Any other information, such as preference or life-time values, that is to be present in the actual announcement using a given method is assumed to be determined by the NAS using means not scoped by this document (e.g. Local configuration on the NAS). Dec, et al. Expires April 20, 2013 [Page 4] Internet-Draft RADIUS IPv6 Access October 2012 While the Framed-IPv6-Prefix Attribute defined in [RFC3162] Section 2.3 causes the route to be advertised in an RA, it cannot be used to configure more specific routes. While the Framed-IPv6-Route Attribute defined in [RFC3162] Section 2.5 causes the route to be configured on the NAS, and potentially announced via an IP routing protocol, depending on the value of Framed-Routing, it does not result in the route being announced in an RA. 2.4. Delegated IPv6 Prefix Pool DHCPv6 Prefix Delegation (DHCPv6-PD) [RFC3633] involves a delegating router selecting a prefix and delegating it on a temporary basis to a requesting router. The delegating router may implement a number of strategies as to how it chooses what prefix is to be delegated to a requesting router, one of them being the use of a local named prefix pool. The Delegated-IPv6-Prefix-Pool Attribute allows the RADIUS server to convey a prefix pool name to a NAS hosting a DHCPv6-PD server and acting as a delegating router. Since DHCPv6 Prefix Delegation can be used with SLAAC on the same network, it is possible for the Delegated-IPv6-Prefix-Pool and Framed-IPv6-Pool attributes to be included within the same packet. To avoid ambiguity in this scenario, use of the Delegated-IPv6 -Prefix-Pool attribute should be restricted to authorization and accounting of prefix pools used in DHCPv6 Prefix Delegation and the Framed-IPv6-Pool attribute should be used for authorization and accounting of prefix pools used in SLAAC. 2.5. Stateful IPv6 address pool DHCPv6 [RFC3315] provides a mechanism to assign one or more non- temporary IPv6 addresses to hosts. Section 3.1 introduces the Framed-IPv6-Address Attribute to be used for providing a DHCPv6 server residing on a NAS with one or more IPv6 addresses to be assigned to the clients. An alternative way to achieve a similar result is for the NAS to select the IPv6 address to be assigned from an address pool configured for this purpose on the NAS. This document specifies the Stateful-IPv6-Address-Pool attribute to allow the RADIUS server to convey a pool name to be used for such stateful DHCPv6 based addressing, and any subsequent accounting. 3. Attributes The fields shown in the diagrams below are transmitted from left to right. Dec, et al. Expires April 20, 2013 [Page 5] Internet-Draft RADIUS IPv6 Access October 2012 3.1. Framed-IPv6-Address This Attribute indicates an IPv6 Address that is assigned to the NAS- facing interface of the RG/host. It MAY be used in Access-Accept packets, and MAY appear multiple times. It MAY be used in an Access- Request packet as a hint by the NAS to the server that it would prefer these IPv6 address(es), but the server is not required to honor the hint. Since it is assumed that the NAS will add a route corresponding to the address, it is not necessary for the server to also send a host Framed-IPv6-Route attribute for the same address. This Attribute can be used by a DHCPv6 process on the NAS to assign a unique IPv6 address to the RG/host. A summary of the Framed-IPv6-Address Attribute format is shown below. The format of the address is as per [RFC3162]. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Address (cont) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Address (cont) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Address (cont) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Address (cont.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type TBA1 for Framed-IPv6-Address Length 18 Address The IPv6 address field contains a 128-bit IPv6 address. 3.2. DNS-Server-IPv6-Address The DNS-Server-IPv6-Address Attribute contains the IPv6 address of a DNS server. This attribute MAY be included multiple times in Access- Accept packets, when the intention is for a NAS to announce more than one DNS server addresses to a RG/host. The same order of the attributes is expected to be followed in the announcements to the client. The attribute MAY be used in an Access-Request packet as a hint by the NAS to the server regarding the DNS IPv6 Address, but the Radius server is not required to honor the hint. Dec, et al. Expires April 20, 2013 [Page 6] Internet-Draft RADIUS IPv6 Access October 2012 The content of this attribute can be inserted in a DHCPv6 option as specified in [RFC3646]. A summary of the DNS-Server-IPv6-Address Attribute format is given below. The format of the address is as per [RFC3162]. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Address (cont) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Address (cont) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Address (cont) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Address (cont.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type TBA2 for DNS-Server-IPv6-Address Length 18 Address The 128-bit IPv6 address of a DNS server. 3.3. Route-IPv6-Information This Attribute specifies a prefix (and corresponding route) for the user on the NAS, which is to be announced using the Route Information Option defined in "Default Router Preferences and More Specific Routes" [RFC4191] Section 2.3. It is used in the Access-Accept packet and can appear multiple times. It MAY be used in an Access-Request packet as a hint by the NAS to the server, but the server is not required to honor the hint. The Route-IPv6-Information attribute format is depicted below. The format of the prefix is as per [RFC3162]. Dec, et al. Expires April 20, 2013 [Page 7] Internet-Draft RADIUS IPv6 Access October 2012 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Reserved | Prefix-Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . Prefix (variable) . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type TBA3 for Route-IPv6-Information Length Length in bytes. At least 4 and no larger than 20; typically 12 or less. Prefix Length 8-bit unsigned integer. The number of leading bits in the Prefix that are valid. The value ranges from 0 to 128. The prefix field is 0, 8 or 16 octets depending on Length. Prefix Variable-length field containing an IP prefix. The Prefix Length field contains the number of valid leading bits in the prefix. The bits in the prefix after the prefix length (if any) are reserved and MUST be initialized to zero. 3.4. Delegated-IPv6-Prefix-Pool This Attribute contains the name of an assigned pool that SHOULD be used to select an IPv6 delegated prefix for the user on the NAS. If a NAS does not support prefix pools, the NAS MUST ignore this Attribute. It MAY be used in an Access-Request packet as a hint by the NAS to the server regarding the pool, but the server is not required to honor the hint. A summary of the Delegated-IPv6-Prefix-Pool Attribute format is shown below. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | String... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type Dec, et al. Expires April 20, 2013 [Page 8] Internet-Draft RADIUS IPv6 Access October 2012 TBA4 for Delegated-IPv6-Prefix-Pool Length Length in bytes. At least 3. String The string field contains the name of an assigned IPv6 prefix pool configured on the NAS. The field is not NULL (hexadecimal 00) terminated. 3.5. Stateful-IPv6-Address-Pool This Attribute contains the name of an assigned pool that SHOULD be used to select an IPv6 address for the user on the NAS. If a NAS does not support address pools, the NAS MUST ignore this Attribute. A summary of the Stateful-IPv6-Address-Pool Attribute format is shown below. It MAY be used in an Access-Request packet as a hint by the NAS to the server regarding the pool, but the server is not required to honor the hint. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | String... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type TBA5 for Stateful-IPv6-Address-Pool Length Length in bytes. At least 3. String The string field contains the name of an assigned IPv6 stateful address pool configured on the NAS. The field is not NULL (hexadecimal 00) terminated. 3.6. Table of attributes The following table provides a guide to which attributes may be found in which kinds of packets, and in what quantity. The optional inclusion of the options in Access Request messages is intended to allow for a network access server (NAS) to provide the RADIUS server with a hint of the attributes in advance of user authentication, which may be useful in cases where a user re-connects or has a static address. The server is under no obligation to honor such hints. Dec, et al. Expires April 20, 2013 [Page 9] Internet-Draft RADIUS IPv6 Access October 2012 Request Accept Reject Challenge Accounting # Attribute Request 0+ 0+ 0 0 0+ TBA1 Framed-IPv6-Address 0+ 0+ 0 0 0+ TBA2 DNS-Server-IPv6-Address 0+ 0+ 0 0 0+ TBA3 Route-IPv6-Information 0+ 0+ 0 0 0+ TBA4 Delegated-IPv6-Prefix-Pool 0+ 0+ 0 0 0+ TBA5 Stateful-IPv6-Address-Pool 4. Diameter Considerations Given that the Attributes defined in this document are allocated from the standard RADIUS type space (see Section 6), no special handling is required by Diameter entities. 5. Security Considerations This document describes the use of RADIUS for the purposes of authentication, authorization and accounting in IPv6-enabled networks. In such networks, the RADIUS protocol may run either over IPv4 or over IPv6. Known security vulnerabilities of the RADIUS protocol apply to the attributes defined in this document. Since IPsec is natively defined for IPv6, it is expected that running RADIUS implementations supporting IPv6 may want to run over IPsec. Where RADIUS is run over IPsec and where certificates are used for authentication, it may be desirable to avoid management of RADIUS shared secrets, so as to leverage the improved scalability of public key infrastructure. 6. IANA Considerations This document requires the assignment of five new RADIUS Attribute Types in the "Radius Types" registry (currently located at http:// www.iana.org/assignments/radius-types for the following attributes: o Framed-IPv6-Address o DNS-Server-IPv6-Address o Route-IPv6-Information o Delegated-IPv6-Prefix-Pool o Stateful-IPv6-Address-Pool 7. Acknowledgements The authors would like to thank Bernard Aboba, Benoit Claise, Peter Deacon, Alan DeKok, Alfred Hines, Jouni Korhonen, Roberta Maglione, Leaf Yeh, and Mark Smith for their help and comments in reviewing this document. 8. References Dec, et al. Expires April 20, 2013 [Page 10] Internet-Draft RADIUS IPv6 Access October 2012 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4862] Thomson, S., Narten, T. and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, September 2007. 8.2. Informative References [RFC3162] Aboba, B., Zorn, G. and D. Mitton, "RADIUS and IPv6", RFC 3162, August 2001. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6", RFC 3633, December 2003. [RFC3646] Droms, R., "DNS Configuration options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3646, December 2003. [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and More-Specific Routes", RFC 4191, November 2005. [RFC4818] Salowey, J. and R. Droms, "RADIUS Delegated-IPv6-Prefix Attribute", RFC 4818, April 2007. [RFC6106] Jeong, J., Park, S., Beloeil, L. and S. Madanapalli, "IPv6 Router Advertisement Options for DNS Configuration", RFC 6106, November 2010. Authors' Addresses Wojciech Dec (editor) Cisco Systems, Inc. Haarlerbergweg 13-19 Amsterdam , NOORD-HOLLAND 1101 CH Netherlands Email: wdec@cisco.com Dec, et al. Expires April 20, 2013 [Page 11] Internet-Draft RADIUS IPv6 Access October 2012 Behcet Sarikaya Huawei USA 1700 Alma Dr. Suite 500 Plano, TX US Phone: +1 972-509-5599 Email: sarikaya@ieee.org Glen Zorn Network Zen 1310 East Thomas Street Seattle, WA US Email: gwz@net-zen.net David Miles Google Email: David.Miles@google.com Benoit Lourdelet France Email: blourdelet@aim.com Dec, et al. Expires April 20, 2013 [Page 12]