Radext Working Group B. Lourdelet Internet-Draft W. Dec, Ed. Intended status: Standards Track Cisco Systems, Inc. Expires: July 14, 2011 B. Sarikaya Huawei USA G. Zorn Network Zen D. Miles Alcatel-Lucent January 10, 2011 RADIUS attributes for IPv6 Access Networks draft-ietf-radext-ipv6-access-03.txt Abstract This document specifies IPv6 RADIUS attributes, which complement those of RFC3162, and are intended to be used in residential broadband networks, where specific user configuration information is expected to be passed as part of the AAA process between a NAS and an AAA server. The attributes cover the assignment or reporting of the following; a specific host IPv6 address; a recursive DNS IPv6 server address; a specific IPv6 route announced to a host; a named IPv6 delegated prefix pool to be used for assignments to an accessing host. 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." Lourdelet, et al. Expires July 14, 2011 [Page 1] Internet-Draft RADIUS IPv6 Access January 2011 This Internet-Draft will expire on July 14, 2011. Copyright Notice Copyright (c) 2011 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. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Lourdelet, et al. Expires July 14, 2011 [Page 2] Internet-Draft RADIUS IPv6 Access January 2011 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Deployment Scenarios . . . . . . . . . . . . . . . . . . . . . 4 2.1. IPv6 Address Assignment . . . . . . . . . . . . . . . . . 5 2.2. Recursive DNS Servers . . . . . . . . . . . . . . . . . . 6 2.3. IPv6 Route Information . . . . . . . . . . . . . . . . . . 6 2.4. Delegated IPv6 Prefix Pool . . . . . . . . . . . . . . . . 6 3. Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1. Framed-IPv6-Address . . . . . . . . . . . . . . . . . . . 7 3.2. DNS-Server-IPv6-Address . . . . . . . . . . . . . . . . . 8 3.3. Route-IPv6-Information . . . . . . . . . . . . . . . . . . 9 3.4. Delegated-IPv6-Prefix-Pool . . . . . . . . . . . . . . . . 10 3.5. Table of attributes . . . . . . . . . . . . . . . . . . . 10 3.6. RFC3162 Attribute coexistance . . . . . . . . . . . . . . 11 4. Diameter Considerations . . . . . . . . . . . . . . . . . . . 11 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . . 12 8.2. Informative References . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Lourdelet, et al. Expires July 14, 2011 [Page 3] Internet-Draft RADIUS IPv6 Access January 2011 1. Introduction In IPv6 deployments DHCPv6 and/or ICMPv6 Router Advertisements can be used to convey configuration information by a NAS towards accessing hosts. Such information typically needs to be provisioned on the NAS and may be done so on a per host or user basis using the AAA process. This document specifies IPv6 RADIUS attributes used to support configuration information allowed for by DHCPv6 and/or ICMPv6, which complement the existing set defined in [RFC3162] and [RFC4818]. Specifically, attributes supporting the following information in Radius are covered by this draft: o The assignment or reporting of specific IPv6 addresses assigned to hosts (where host address assignmenet takes place via DHCPv6) o The passing by the NAS of IPv6 recursive DNS server addresses to a host (where the NAS and accessing host use DHCPv6 or [RFC5006]) o The passing of IPv6 Route information by the NAS intended to be advertised to the host (where the NAS and accessing host use [RFC4191] or equivalent mechanisms). o The assignment of a named prefix pool intended for Prefix Delegation to a host (where the NAS and accessing host use [RFC3633]). 2. Deployment Scenarios A common broadband network scenario is illustrated in Figure 1. It is composed of a IP Routing Residential Gateway (RG) or host, a Layer 2 Access-Node (e.g. a DSLAM), one or more IP Network Access Servers (NASes), and an AAA server. The RG or host are expected to be multi homed at Layer 2 to both NASes. Layer 2 Connectivity between the host and NAS can be either via PPPoE or IP over Ethernet, and established dynamically. Lourdelet, et al. Expires July 14, 2011 [Page 4] Internet-Draft RADIUS IPv6 Access January 2011 +-----+ (Radius) | AAA | ...........>| | . +--+--+ v ^ +---+---+ . | NAS | .(Radius) | | . +---+---+ v +------+ | +---+---+ +------+ | AN | | | NAS | | RG/ +-------| +-----------+----------+ | | host | | | | | +------+ (DSL) +------+ (Ethernet) +-------+ Figure 1 In the illustrated deployment scenario the NASes are assumed to embed a DHCPv6 server function that allows them to locally handle any DHCPv6 requests issued by RGs/hosts. This scenario is particularly useful in illustrating the possible interaction between RADIUS and DHCPv6, however the options defined in this document are not restricted to be used only in the presence of such embedded functionality. The NAS interfaces to the AAA server by means of the RADIUS protocol. The AAA server is expected to authenticate each accessing RG/host and to return to the NAS per host authorization and network configuration information that can comprise of: One or more IP addresses Recursive DNS servers intended to be announced to the host; specific IP routes to be announced to the host by a NAS; an explicit 128 bit IPv6 address that is to be statefuly assigned to a given RG/host. The NAS can also report some of this information back to the AAA server in accounting messages. The known methods by which the NAS can communicate the above information to RG/hosts are explained in each of the following sub- sections. 2.1. IPv6 Address Assignment DHCPv6 [RFC3315] provides a mechanism to assign one or more or non- temporary IPv6 addresses to nodes complementing the ICMPv6 stateless (SLAAC) method [RFC4862]. Simplistically, using SLAAC the NAS announces to a host a /64 IPv6 prefix from which the host construct its full 128 bit IPv6 address by appending an 64-bit interface- identifier. By providing one or more hosts with only a /64 prefix, network operators are have to rely on extra processes or procedures Lourdelet, et al. Expires July 14, 2011 [Page 5] Internet-Draft RADIUS IPv6 Access January 2011 to determine the exact IPv6 address that is being used by a host. Such procedures typically involve processing of two existing [RFC3162] attributes. In contrast to SLAAC, DHCPv6 allows for an operator to uniquely assign a non-temporary address to a give host. This document specifies a single RADIUS attribute intended to be used for the assignment or accounting of a full 128-bit IPv6 addresses to a host (typically via DHCPv6), without overloading or modifying the implementations associated to the existing attributes. 2.2. Recursive DNS Servers DHCPv6 provides an option for recursive DNS servers to hosts, as does ICMPv6 with Router Advertisements supporting the experimental [RFC5006] option. Existing IETF Radius attributes convey DNS as 32- bit IPv4 addresses and cannot support a 128-bit IPv6 address. This document specifies the RADIUS attribute to convey a list of IPv6 DNS Recursive name server addresses, from an AAA server, which can that can be conveyed by a NAS to a host. 2.3. IPv6 Route Information In scenarios where Stateless Address Autoconfiguration (SLAAC) [RFC4862] is used for address assignment, an ICMPv6 Router Advertisement is multicast by the NAS with one or more Prefix Information Options with the autonomous-bit set to true. In such cases, the Prefix Information Option, is a /64 prefix to which a host appends its locally-generated Interface Id to create a unique 128-bit IPv6 address. [RFC3162] currently defines a Radius Framed-IPv6- Prefix attribute that can be used by a NAS to advertise such on-link prefixes in Router Advertisement messages. An IPv6 Route Information option, defined in [RFC4191] is almost the inverse. It is intended to be used to inform a host connected to the NAS that a specific route is reachable via the NAS. This is particularly desirable in cases where the RG or host are multi-homed to different NASes as shown in Figure 1. This document specifies the RADIUS attribute that allows the AAA system 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. 2.4. Delegated IPv6 Prefix Pool The use of DHCPv6 Prefix Delegation [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 Lourdelet, et al. Expires July 14, 2011 [Page 6] Internet-Draft RADIUS IPv6 Access January 2011 requesting router, one of them being the use of a local named prefix pool. The Delegated IPv6 Prefix Pool attribute is intended to allow the AAA system to convey the selected prefix pool name to a NAS hosting a DHCPv6-PD server and acting as a delegating router. While similar in principle, this attribute is not to be confused with the [RFC3162]Framed-IPv6-Pool attribute, which is intended for selecting an address from a pool for assignment to a user interface nor with [RFC4818] that conveys a specific prefix. 3. Attributes The fields shown in the diagrams below are transmitted from left to right. 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, or it can be used for a-posteriori validation or announcement of an auto configured address to the AAA server. A summary of the Framed-IPv6-Address Attribute format is shown below. 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.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Lourdelet, et al. Expires July 14, 2011 [Page 7] Internet-Draft RADIUS IPv6 Access January 2011 Type TBA1 for Framed-IPv6-Address Length 18 Address The 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 recursive 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 recursive DNS address to an RG/host. The content of this attribute can be inserted in a Router Advertisement as specified in [RFC5006] or mapped to the matching DHCPv6 option. A summary of the DNS-Server-IPv6-Address Attribute format is given below. 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 Lourdelet, et al. Expires July 14, 2011 [Page 8] Internet-Draft RADIUS IPv6 Access January 2011 Address The 128-bit IPv6 address of a DNS server. 3.3. Route-IPv6-Information This Attribute specifies a prefix (and corresponding route) to be authorized for announcement towards the user by the NAS, with the reachable by means of routing towards the NAS. It is used in the Access-Accept packet and can appear multiple times. It may also be used in the Access-Request packet as hint to the server. A summary of the Route-IPv6-Information attribute format is shown below. The route information option defined in [RFC4191] is captured in this and following two attributes. 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 The length of the prefix, in bits; at least 0 and no more than 128; typically 64 or less. 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) up to the byte boundary are reserved and MUST be initialized to zero by the Lourdelet, et al. Expires July 14, 2011 [Page 9] Internet-Draft RADIUS IPv6 Access January 2011 sender and ignored by the receiver. 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. If a NAS does not support multiple prefix pools, the NAS MUST ignore this Attribute. A summary of the Delegated-IPv6-Prefix-Pool Attribute format is shown below. The fields are transmitted from left to right. 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 TBA4 for Delegated-IPv6-Prefix-Pool Length Length in bytes. At least 4. String The string field contains the name of an assigned IPv6 prefix pool configured on the NAS. The field is not NULL (hex 00) terminated. 3.5. Table of attributes The following table provides a guide to which attributes may be found in which kinds of packets, and in what quantity. 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 0-1 0 0 0-1 TBA4 Delegated-IPv6-Prefix-Pool Lourdelet, et al. Expires July 14, 2011 [Page 10] Internet-Draft RADIUS IPv6 Access January 2011 3.6. RFC3162 Attribute coexistance Syntactically, the Framed-IPv6-Address and the [RFC3162] Framed-IPv6- Prefix attributes are identical. In terms of their applied semantics, however the former represents a full 128-bit IPv6 address while the latter a /64 prefix intended to be applied with SLAAC on a NAS access interface. These attributes are envisaged to co-exist in Radius messages and given existing NAS applications for the Framed- IPv6-Prefix it is recommended that each attribute be used for its intended purposes. A functional substitution of one attribute for the other may however be an optional configuration feature of a Radius client and server. 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 three 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 Lourdelet, et al. Expires July 14, 2011 [Page 11] Internet-Draft RADIUS IPv6 Access January 2011 o Route-IPv6-Information o Delegated-IPv6-Prefix-Pool IANA should allocate these numbers from the standard RADIUS Attributes space using the "IETF Review" policy [RFC5226]. 7. Acknowledgements The authors would like to thank Alfred Hines, Alan DeKok, Peter Deacon and Mark Smith for their help and comments in reviewing this document. 8. References 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. [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. [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. Lourdelet, et al. Expires July 14, 2011 [Page 12] Internet-Draft RADIUS IPv6 Access January 2011 [RFC5006] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, "IPv6 Router Advertisement Option for DNS Configuration", RFC 5006, September 2007. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. Authors' Addresses Benoit Lourdelet Cisco Systems, Inc. Village ent. GreenSide, Bat T3, 400, Av de Roumanille, 06410 BIOT - Sophia-Antipolis Cedex France Phone: +33 4 97 23 26 23 Email: blourdel@cisco.com Wojciech Dec (editor) Cisco Systems, Inc. Haarlerbergweg 13-19 Amsterdam , NOORD-HOLLAND 1101 CH Netherlands Email: wdec@cisco.com Behcet Sarikaya Huawei USA 1700 Alma Dr. Suite 500 Plano, TX US Phone: +1 972-509-5599 Email: sarikaya@ieee.org Lourdelet, et al. Expires July 14, 2011 [Page 13] Internet-Draft RADIUS IPv6 Access January 2011 Glen Zorn Network Zen 1310 East Thomas Street Seattle, WA US Email: gwz@net-zen.net David Miles Alcatel-Lucent L3 / 215 Spring St Melbourne, Victoria 3000, Australia Phone: Fax: Email: David.Miles@alcatel-lucent.com URI: Lourdelet, et al. Expires July 14, 2011 [Page 14]