Network Working Group Sheng Jiang (Editor) Internet Draft Yu Fu Intended status: Standards Track Bing Liu Expires: February 3, 2014 Huawei Technologies Co., Ltd August 2, 2013 RADIUS Attribute for 4rd draft-jiang-softwire-4rd-radius-03.txt 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 February 3, 2014. Copyright Notice Copyright (c) 2013 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. Jiang, et al. Expires February 3, 2014 [Page 1] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 Abstract IPv4 Residual Deployment via IPv6 (4rd) is a stateless mechanism for running IPv4 over IPv6-only infrastructure. It provides both IPv4 and IPv6 connectivity services simultaneously during the IPv4/IPv6 co- existing period. The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) 4rd options has been defined to configure 4rd Customer Edge (CE). However, in many networks, the configuration information may be stored in Authentication Authorization and Accounting (AAA) servers while user configuration is mainly from Broadband Network Gateway (BNG) through DHCPv6 protocol. This document defines a Remote Authentication Dial In User Service (RADIUS) attribute that carries 4rd configuration information from AAA server to BNG. The 4rd RADIUS attribute are designed following the simplify principle. It provides just enough information to form the correspondent DHCPv6 4rd option. Table of Contents 1. Introduction ................................................. 3 2. Terminology .................................................. 3 3. 4rd Configuration process with RADIUS ........................ 3 4. Attributes ................................................... 6 4.1. 4rd-Configuration Attribute ............................. 6 4.2. 4rd Non-mapping-rule Parameter option ................... 7 4.3. 4rd Rule Options ........................................ 7 4.4. 4rd Rule Sub Options .................................... 8 4.4.1. Rule-IPv6-Prefix Sub Option ........................ 8 4.4.2. Rule-IPv6-Suffix Sub Option ........................ 9 4.4.3. Rule-IPv4-Prefix Sub Option ....................... 10 4.4.4. Misc Sub Option ................................... 11 4.5. Table of attributes .................................... 11 5. Diameter Considerations ..................................... 12 6. Security Considerations ..................................... 12 7. IANA Considerations ......................................... 12 8. Acknowledgments ............................................. 13 9. References .................................................. 13 9.1. Normative References ................................... 13 9.2. Informative References ................................. 13 Jiang, et al. Expires February 3, 2014 [Page 2] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 1. Introduction Recently providers start to deploy IPv6 and consider how to transit to IPv6. IPv4 Residual Deployment via IPv6 (4rd) [I-D.ietf-softwire-4rd] is a stateless mechanism for running IPv4 over IPv6-only infrastructure. It provides both IPv4 and IPv6 connectivity services simultaneously during the IPv4/IPv6 co-existing period. 4rd has adopted Dynamic Host Configuration Protocol for IPv6 (DHCPv6) [RFC3315] as auto-configuring protocol. The 4rd Customer Edge (CE) uses the DHCPv6 extension options [I-D.ietf-softwire-4rd] to discover 4rd Border Relay and to configure relevant 4rd rules. In many networks, user configuration information may be managed by AAA (Authentication, Authorization, and Accounting) servers. Current AAA servers communicate using the Remote Authentication Dial In User Service (RADIUS) [RFC2865] protocol. In a fixed line broadband network, the Broadband Network Gateways (BNGs) act as the access gateway of users. The BNGs are assumed to embed a DHCPv6 server function that allows them to locally handle any DHCPv6 requests issued by hosts. Since the 4rd configuration information is stored in AAA servers and user configuration is mainly through DHCPv6 protocol between BNGs and hosts/CEs, new RADIUS attributes are needed to propagate the information from AAA servers to BNGs. The 4rd RADIUS attribute are designed following the simplify principle, while providing enough information to form the correspondent DHCPv6 4rd option. [I-D.ietf-softwire-4rd]. 2. Terminology 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 [RFC2119]. The terms 4rd CE and 4rd Border Relay are defined in [I-D.ietf-softwire-4rd]. 3. 4rd Configuration process with RADIUS The below Figure 1 illustrates how the RADIUS protocol and DHCPv6 cooperate to provide 4rd CE with 4rd configuration information. Jiang, et al. Expires February 3, 2014 [Page 3] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 4rd CE BNG AAA Server | | | |------DHCPv6 Solicit----->| | |(Option Request w/ 4rd option) | | |--Access-Request(4rd Attr)-->| | | | | |<--Access-Accept(4rd Attr)---| |<---DHCPv6 Advertisement--| | | | | |------DHCPv6 Request---->| | | (4rd Option) | | |<---- -DHCPv6 Reply-------| | | (4rd option) | | | | | DHCPv6 RADIUS Figure 1: the cooperation between DHCPv6 and RADIUS combining with RADIUS authentication BNGs act as a client of RADIUS and as a DHCPv6 server. First, the 4rd CE MAY initiate a DHCPv6 Solicit message that includes an Option Request option (6) [RFC3315] with the 4rd option [draft-ietf-softwire-4rd] from the 4rd CE. When BNG receives the SOLICIT, it SHOULD initiate an RADIUS Access-Request message, in which the User-Name attribute (1) SHOULD be filled by the 4rd CE MAC address, to the RADIUS server and the User-password attribute (2) SHOULD be filled by the shared 4rd password that has been preconfigured on the DHCPv6 server, requesting authentication as defined in [RFC2865] with 4rd-Configuration attribute, defined in the next Section. If the authentication request is approved by the AAA server, an Access-Accept message MUST contain the 4rd-Configuration Attribute. After receiving the Access-Accept message with 4rd- Configuration Attribute, the BNG SHOULD respond to the user with an Advertisement message. Then the user can request a 4rd Option, the BNG SHOULD reply the user with a message containing the 4rd option. The recommended format of the MAC address is as defined in Calling- Station-Id (Section 3.20 in [RFC3580]) without the SSID (Service Set Identifier) portion. Figure 2 describes another scenario, in which the authorization operation is not coupled with authentication. Authorization relevant to 4RD is done independently after the authentication process. Jiang, et al. Expires February 3, 2014 [Page 4] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 4rd CE BNG AAA Server | | | |------DHCPv6 Request---->| | |(Option Request w/ 4rd option) | | |--Access-Request(4rd Attr)-->| | | | | |<--Access-Accept(4rd Attr)---| | | | |<------DHCPv6 Reply-------| | | (4rd option) | | | | | DHCPv6 RADIUS Figure 2: the cooperation between DHCPv6 and RADIUS decoupled with RADIUS authentication In the abovementioned scenario, the Access-Request packet SHOULD contain a Service-Type attribute (6) with the value Authorize Only (17); thus, according to [RFC5080], the Access-Request packet MUST contain a State attribute that obtained from the previous authentication process. In both above-mentioned scenarios, Message-authenticator (type 80) [RFC2869] SHOULD be used to protect both Access-Request and Access- Accept messages. After receiving the 4rd-Configuration Attribute in the initial Access-Accept, the BNG SHOULD store the received 4rd configuration parameters locally. When the 4rd CE sends a DHCPv6 Request message to request an extension of the lifetimes for the assigned address, the BNG does not have to initiate a new Access-Request towards the AAA server to request the 4rd configuration parameters. The BNG could retrieves the previously stored 4rd configuration parameters and use them in its reply. If the BNG does not receive the 4rd-Configuration Attribute in the Access-Accept it MAY fallback to a pre-configured default 4rd configuration, if any. If the BNG does not have any pre-configured default 4rd configuration or if the BNG receives an Access-Reject, the tunnel cannot be established. As specified in [RFC3315], section 18.1.4, "Creation and Transmission of Rebind Messages ", if the DHCPv6 server to which the DHCPv6 Renew message was sent at time T1 has not responded by time T2, the 4rd CE (DHCPv6 client) enters the Rebind state and attempts to contact any available server. In this situation the secondary BNG receiving the DHCPv6 message MUST initiate a new Access-Request towards the AAA Jiang, et al. Expires February 3, 2014 [Page 5] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 server. The secondary BNG MAY include the 4rd-Configuration Attribute in its Access-Request. 4. Attributes This section defines 4rd-Configuration Attribute which is used in the 4rd scenario. The attribute design follows [RFC6158]. The 4rd RADIUS attribute are designed following the simplify principle. The sub options are organized into two categories: the necessary and the optional. 4.1. 4rd-Configuration Attribute The 4rd-Configuration Attribute is structured as follows: 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 | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | | + 4rd Option(s) + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type TBD Length 6 + the length of the Rule option(s) Sub Option a variable field that may contains a 4rd non-mapping-rule parameter option andone or more Rule option(s), defined in Section 4.2 and 4.3. Jiang, et al. Expires February 3, 2014 [Page 6] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 4.2. 4rd Non-mapping-rule Parameter option 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-code = OPTION_4RD | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |H| 0 |T| traffic-class | domain-pmtu | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 1 Length 4 H bit Hub&spoke topology (= 1 if Yes) T bit Traffic-class flag (= 1 if a Tunnel traffic class is provided) traffic-class Tunnel-traffic class domain-pmtu Domain PMTU (at least 1280) 4.3. 4rd Rule Options Depending on deployment scenario, at least one BR Mapping Rule one and one or more CE Mapping Rules MUST be included in one 4rd- Configuration Attribute. Jiang, et al. Expires February 3, 2014 [Page 7] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 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 | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | | + Sub Options + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 2 BR Mapping Rule 3 CE Mapping Rule Length 2 + the length of the sub options Sub Option a variable field that contains necessary sub options defined in Section 4.3 and zero or several optional sub options, defined in Section 4.4. 4.4. 4rd Rule Sub Options Rule-IPv6-Prefix Sub Option and Rule-IPv4-Prefix Sub Option are necessary for every 4rd Rule option. They should appear for once and only once. Different from [I-D.ietf-softwire-4rd], EA-Len, Embedded- Address (EA) length, is not present at all, because it can be calculated by the combine of prefix4len, prefix6-len, excluded ports and off bits. 4.4.1. Rule-IPv6-Prefix Sub Option The IPv6 Prefix sub option is follow the framed IPv6 prefix designed in [RFC3162]. Jiang, et al. Expires February 3, 2014 [Page 8] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SubType | SubLen | Reserved | prefix6-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | rule-ipv6-prefix | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ SubType 0 (SubType number, for the Rule-IPv6-Prefix6 sub option) SubLen 20 (the length of the Rule-IPv6-Prefix6 sub option) Reserved Reserved for future usage. It should be set to all zero. prefix6-len length of the IPv6 prefix, specified in the rule-ipv6-prefix field, expressed in bits rule-ipv6-prefix a 128-bits field that specifies an IPv6 prefix that appears in a 4rd rule 4.4.2. Rule-IPv6-Suffix Sub Option 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SubType | SubLen | suffix6-len | ipv6-suffix | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ SubType 1 (SubType number, for the Rule-IPv6-Suffix6 sub option) SubLen Jiang, et al. Expires February 3, 2014 [Page 9] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 4 (the length of the Rule-IPv6-Suffix6 sub option) prefix6-len length of the IPv6 suffix, specified in the rule-ipv6-suffix field, expressed in bits. In attendance, the value should be 1~4 only. rule-ipv6-suffix a 8-bits field that specifies an IPv6 suffix that appears in a 4rd rule 4.4.3. Rule-IPv4-Prefix Sub Option 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SubType | SubLen | Reserved | prefix4-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | rule-ipv4-prefix | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ SubType 2 (SubType number, for the Rule-IPv4-Prefix6 sub option) SubLen 8 (the length of the Rule-IPv4-Prefix6 sub option) Reserved Reserved for future usage. It should be set to all zero. Prefix4-len length of the IPv6 prefix, specified in the rule-ipv6-prefix field, expressed in bits rule-ipv4-prefix a 32-bits field that specifies an IPv4 prefix that appears in a 4rd rule Jiang, et al. Expires February 3, 2014 [Page 10] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 4.4.4. Misc Sub Option 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SubType | SubLen | Reserved |W| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ SubType 3 (SubType number, for the Rule-IPv4-Prefix6 sub option) SubLen 1 (the length of the Rule-IPv4-Prefix6 sub option) Reserved Reserved for future usage. It should be set to all zero. W bit WKP authorized, = 1 if set 4.5. 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 0-1 0-1 0 0 0-1 TBD1 4rd- Configuration 0-1 0-1 0 0 0-1 1 User-Name 0-1 0 0 0 0-1 2 User-Password 0-1 0-1 0 0 0-1 6 Service-Type 0-1 0-1 0-1 0-1 0-1 80 Message-Authenticator The following table defines the meaning of the above table entries. 0 This attribute MUST NOT be present in packet. 0+ Zero or more instances of this attribute MAY be present in packet. 0-1 Zero or one instance of this attribute MAY be present in packet. Jiang, et al. Expires February 3, 2014 [Page 11] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 1 Exactly one instance of this attribute MUST be present in packet. 5. Diameter Considerations This attribute is usable within either RADIUS or Diameter [RFC6733]. Since the Attributes defined in this document will be allocated from the standard RADIUS type space, no special handling is required by Diameter entities. 6. Security Considerations In 6rd scenarios, both CE and BNG are within a provider network, which can be considered as a closed network and a lower security threat environment. A similar consideration can be applied to the RADIUS message exchange between BNG and the AAA server. Known security vulnerabilities of the RADIUS protocol are discussed in RFC 2607 [RFC2607], RFC 2865 [RFC2865], and RFC 2869 [RFC2869]. Use of IPsec [RFC4301] for providing security when RADIUS is carried in IPv6 is discussed in RFC 3162 [RFC3162]. A malicious user may use MAC address spoofing and/or dictionary attack on the shared 4rd password that has been preconfigured on the DHCPv6 server to get unauthorized 4rd configuration information. Security considerations for 4RD specific between 4RD CE and BNG are discussed in [I-D.ietf-softwire-4rd]. Furthermore, generic DHCPv6 security mechanisms can be applied DHCPv6 intercommunication between 4RD CE and BNG. Security considerations for the Diameter protocol are discussed in [RFC6733]. 7. IANA Considerations This document requires the assignment of two new RADIUS Attributes Types in the "Radius Types" registry (currently located at http://www.iana.org/assignments/radius-types for the following attributes: o 4rd-Configuration TBD1 IANA should allocate the numbers from the standard RADIUS Attributes space using the "IETF Review" policy [RFC5226]. Jiang, et al. Expires February 3, 2014 [Page 12] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 8. Acknowledgments The authors would like to thank for valuable comments. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, June 2000. [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. [RFC4301]Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, December 2005. [RFC5080] Nelson, D. and DeKok A., "Common Remote Authentication Dial In User Service (RADIUS) Implementation Issues and Suggested Fixes", RFC 5080, December 2007. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 5226, May 2008. [RFC6158] DeKok, A. and G. Weber, "RADIUS Design Guidelines", RFC 6158, March 2011. [RFC6733] V. Fajardo, Ed., J. Arkko, J. Loughney, G. Zorn, Ed., "Diameter Base Protocol", RFC 6733, October 2012. [I-D.ietf-softwire-4rd] R. Despres, et al., "IPv4 Residual Deployment via IPv6 - a unified Stateless Solution (4rd)", draft-ietf-softwire-4rd, working in progress. 9.2. Informative References [RFC2607] Aboba, B. and J. Vollbrecht, "Proxy Chaining and Policy Implementation in Roaming", RFC 2607, June 1999. Jiang, et al. Expires February 3, 2014 [Page 13] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 [RFC2869] Rigney, C., Willats, W., and P. Calhoun, "RADIUS Extensions", RFC 2869, June 2000. Jiang, et al. Expires February 3, 2014 [Page 14] Internet-Draft draft-jiang-softwire-4rd-radius-03 August 2013 Author's Addresses Sheng Jiang (Editor) Huawei Technologies Co., Ltd Q14 Huawei Campus, 156 BeiQi Road, ZhongGuan Cun, Hai-Dian District, Beijing 100085 P.R. China EMail: jiangsheng@huawei.com Yu Fu Huawei Technologies Co., Ltd Q14 Huawei Campus, 156 BeiQi Road, ZhongGuan Cun, Hai-Dian District, Beijing 100085 P.R. China EMail: eleven.fuyu@huawei.com Bing Liu Huawei Technologies Co., Ltd Q14 Huawei Campus, 156 BeiQi Road, ZhongGuan Cun, Hai-Dian District, Beijing 100085 P.R. China EMail: leo.liubing@huawei.com