Network Working Group P. Duffy Internet-Draft Cisco Intended status: Standards Track S. Chakrabarti Expires: March 25, 2011 IP Infusion R. Cragie PG&E Y. Ohba (Ed.) Toshiba A. Yegin Samsung September 21, 2010 Protocol for Carrying Authentication for Network Access (PANA) Relay Element draft-ohba-pana-relay-00 Abstract This document specifies PANA (Protocol for carrying Authentication for Network Access) Relay Element functionality which enables PANA messaging between a PaC (PANA Client) and a PAA (PANA Authentication Agent) where the two nodes cannot reach each other by means of regular IP routing. Status of this Memo This Internet-Draft is submitted to IETF 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 March 25, 2011. Copyright Notice Copyright (c) 2010 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 Duffy, et al. Expires March 25, 2011 [Page 1] Internet-Draft PANA Forwarding Element September 2010 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Specification of Requirements . . . . . . . . . . . . . . . 3 2. PANA Relay Element . . . . . . . . . . . . . . . . . . . . . . 3 3. PANA messages for Relay Operation . . . . . . . . . . . . . . . 5 3.1. PANA-Relay . . . . . . . . . . . . . . . . . . . . . . . . 5 4. PANA AVPs for Relay Operation . . . . . . . . . . . . . . . . . 6 4.1. PaC-Information AVP . . . . . . . . . . . . . . . . . . . . 6 4.2. Relayed-PDU AVP . . . . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 8.1. Normative References . . . . . . . . . . . . . . . . . . . 7 8.2. Informative References . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Duffy, et al. Expires March 25, 2011 [Page 2] Internet-Draft PANA Forwarding Element September 2010 1. Introduction PANA (Protocol for carrying Authentication for Network Access) [RFC5191] is a UDP-based protocol to perform EAP authentication between a PaC (PANA Client) and a PAA (PANA Authentication Agent). This document specifies PANA Relay Element (PRE) functionality which enables PANA messaging between a PaC and a PAA where the two nodes cannot reach each other by means of regular IP routing. For example, in ZigBee IP architecture (Editor's Note: a reference to ZigBee IP specification is to be added here when it is under public review), a joining-node (PaC) can only use a link-local IPv6 address to communicate with a parent router prior to PANA authentication. The PAA resides in a 6LBR (6LowPAN Border Router) [I-D.ietf-6lowpan-nd] which is often multiple IP hops away from the PaC. The PRE implemented on the parent router is used for relaying PANA PDUs between the PaC and the PAA in this scenario. 1.1. Specification of Requirements In this document, several words are used to signify the requirements of the specification. These words are often capitalized. 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]. 2. PANA Relay Element The PANA Relay Element (PRE) is a node that is located between the PaC and the PAA. It is responsible for relaying the PANA PDUs between the PaC and the PAA. The PRE does not need to maintain per- PaC state. From the PaC's perspective the PRE appears as the PAA. Normal IP routing is performed between the PRE and the PAA. It is assumed that the PRE's IP address that is reachable from the PaC is known to the PaC prior to PANA authentication by some means that is not specified in this document. It is also assumed that the PAA's IP address that is reachable from the PRE is known to the PRE by some means that is not specified in this document. The PRE and the PAA supporting the relay operation function as follows. The relay operation requires that a PANA session is initiated by the PaC, i.e., the first message that the PRE relays for any PANA session is a PCI (PANA-Client-Initiation) message. When the PRE receives a PANA PDU from the PaC, it creates a PANA- Duffy, et al. Expires March 25, 2011 [Page 3] Internet-Draft PANA Forwarding Element September 2010 Relay (PRY) message containing a Relayed-PDU AVP and a PaC- Information AVP. The Relayed-PDU AVP encapsulates the entire PANA PDU received from the PaC. The PaC-Information AVP contains the PaC's IP address and UDP port number. The PRY message is sent to the PAA. When the PAA receives the PRY, it retrieves the PaC-originated PANA PDU from the Relayed-PDU AVP and the PaC's IP address and UDP port number from the PaC-Information AVP. The PaC-originated PANA PDU is processed in the same way as specified in RFC 5191, with the following exceptions: (a) The PaC's IP address and UDP port number are maintained in the PANA session attribute "IP address and UDP port number of the PaC". (b) The source IP address and UDP port number of the PRY is stored in a new PANA session attribute "IP address and UDP port number of the PRE". A PANA session is referred to as a relayed PANA session if this attribute has a non-null value. When the PAA originates a PANA PDU for a relayed PANA session, it sends a PRY message to the PRE's IP address and UDP port number. The PRY message includes a Relayed-PDU AVP containing the PAA-originated PANA PDU and also includes a PaC-Information AVP containing the PaC's IP address and UDP port number. When the PRE receives the PRY message, it retrieves the PAA- originated PANA PDU from the Relayed-PDU and the PaC's IP address and UDP port number from and PaC-Information AVPs. The PAA-originated PANA PDU is sent to the PaC's IP address and UDP port number. The Session Identifier and Sequence Number of a PRY message are set to zero. A PRY message is never retransmitted by the PRE or the PAA. The PRE and PAA do not advance its incoming or outgoing sequence numbers for request when transmitting or receiving a PRY message. Note that the PANA message carried in a Relayed-PDU may be retransmitted by the PaC or PAA, leading to transmission of another PRY carrying the same Relayed-PDU. If direct IP routing becomes available (e.g., after the successful PANA authentication as in the case of Zigbee IP), the PaC may choose to directly communicate with the PAA without use of the relay operation. The IP address update procedure defined in [RFC5191] may be performed to switch to non-relay operation. Figure 1 is an example message flow with a PRE. Duffy, et al. Expires March 25, 2011 [Page 4] Internet-Draft PANA Forwarding Element September 2010 PaC(IP1:p1) (IP2a:716)PRE(IP2b:p2) (IP3)PAA srcIP:port->dstIP:port -------- ------------------------ ------- ---------------------- 1. ----PCI---> IP1:p1 -> IP2a:716 2. ----PRY[P{IP1:p1},R{PCI}]---> IP2b:p2 -> IP3:716 3. <---PRY[P{IP1:p1},R{PAR}]---- IP3:716 -> IP2b:p2 4. <----PAR--- IP2a:716 -> IP1:p1 5. ----PAN---> IP1:p1 -> IP2a:716 6. ----PRY[P{IP1:p1},R{PAN}]---> IP2b:p2 -> IP3:716 7. <---PRY[P{IP1:p1},R{PAR}]---- IP3:716 -> IP2b:p2 8. <----PAR--- IP2a:716 -> IP1:p1 9. ----PAN---> IP1:p1 -> IP2a:716 10. ----PRY[P{IP1:p1},R{PAN}]---> IP2b:p2 -> IP3:716 IP1 is the IP address of PaC. IP2a and IP2b are the IP addresses of PRE. The two IP address may be the same. IP3 is the IP address of PAA. P: PaC-Information AVP R: Relayed-PDU AVP Figure 1: Example Call Message for PANA Relay 3. PANA messages for Relay Operation 3.1. PANA-Relay The PANA-Relay (PRY) message is sent by the PRE to the PAA or by the PAA to the PRE. It contains one PaC-Information AVP and one Relayed- PDU AVP. The PRY message MAY carry other AVPs. In a PRE-originated PFY message, the PaC-Information AVP contains an IP address and the UDP port number of the PANA PDU that was originated by the PaC and is contained in the Relayed-PDU AVP. Duffy, et al. Expires March 25, 2011 [Page 5] Internet-Draft PANA Forwarding Element September 2010 In a PAA-originated PRY message, the information in the PaC- Information AVP MUST be copied from the "IP address and UDP port number of the PaC" attribute of the associated PANA session [RFC5191]. The Session Identifier and Sequence Number field of any PRY message MUST be set to zero. A PRY message MUST NOT be retransmitted by the PRE or the PAA. The PRE and PAA MUST NOT advance its incoming or outgoing sequence numbers for request when transmitting or receiving a PRY message. PANA-Relay ::= < PANA-Header: TBD> { PaC-Information } { Relayed-PANA-PDU } *[ AVP ] 4. PANA AVPs for Relay Operation 4.1. PaC-Information AVP The PaC-Information AVP (AVP Code TBD) is of type OctetString and contains an IP address (16-octet for IPv6 address and 4-octet for IPv4 address) followed by 2-octet UDP port number of the PaC, both encoded in network-byte order. 4.2. Relayed-PDU AVP The Relayed-PANA-PDU (AVP Code TBD) is of type OctetString and contains a relayed PANA PDU. 5. Security Considerations Since the PRE does not maintain per-PaC state, the PRE is robust against resource consumption DoS (Deniable of Service) attack. The security properties of the PaC and PAA remain the same as [RFC5191]. If cryptographic integrity protection is needed for PRY messages, it MUST be provided by either a PANA layer protection mechanism (TBD) or a lower-layer protection mechanism using, e.g., IPsec. (Editor's note: PANA-layer integrity protection for PRY messages needs more investigation considering that PRY messages are not retransmitted and therefore sequence numbers are not used for them, whereas sequence numbers are needed for protecting other PANA messages using a PANA SA. As a result, PANA-layer integrity Duffy, et al. Expires March 25, 2011 [Page 6] Internet-Draft PANA Forwarding Element September 2010 protection for PRY messages may require a different mechanism from that is defined in [RFC5191]. The authors will continue to investigate candidate PANA-layer integrity protection mechanisms for PRY messages and define one in a future revision of the document.) 6. IANA Considerations As described in Sections Section 3 and Section 4, and following the new IANA allocation policy on PANA messages [RFC5872], one Message Type and two PANA AVP Codes need to be assigned. o One standard Message Type for PANA-Relay (PRY) message. o One standard AVP Code for PaC-Information AVP. o One standard AVP Code for Relayed-PDU AVP. 7. Acknowledgments The authors would like to thank Vlad Gherghisan for valuable comments. 8. References 8.1. Normative References [RFC5191] Forsberg, D., Ohba, Y., Patil, B., Tschofenig, H., and A. Yegin, "Protocol for Carrying Authentication for Network Access (PANA)", RFC 5191, May 2008. [RFC5872] Arkko, J. and A. Yegin, "IANA Rules for the Protocol for Carrying Authentication for Network Access (PANA)", RFC 5872, May 2010. 8.2. Informative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks", RFC 2464, December 1998. [I-D.ietf-6lowpan-nd] Shelby, Z., Chakrabarti, S., and E. Nordmark, "Neighbor Discovery Optimization for Low-power and Lossy Networks", Duffy, et al. Expires March 25, 2011 [Page 7] Internet-Draft PANA Forwarding Element September 2010 draft-ietf-6lowpan-nd-13 (work in progress), September 2010. Authors' Addresses Paul Duffy Cisco Systems 200 Beaver Brook Road Boxborough, MA 01719 USA Email: paduffy@cisco.com Samita Chakrabarti IP Infusion 1188 Arquest Street Sunnyvale, CA USA Email: samitac@ipinfusion.com Robert Cragie Pacific Gas & Electric Gridmerge Ltd., 89 Greenfield Crescent Wakefield, WF4 4WA UK Email: robert.cragie@gridmerge.com Yoshihiro Ohba Toshiba Corporate Research and Development Center 1 Komukai-Toshiba-cho Saiwai-ku, Kawasaki, Kanagawa 212-8582 Japan Phone: +81 44 549 2127 Email: yoshihiro.ohba@toshiba.co.jp Duffy, et al. Expires March 25, 2011 [Page 8] Internet-Draft PANA Forwarding Element September 2010 Alper Yegin Samsung Istanbul Turkey Email: alper.yegin@yegin.org Duffy, et al. Expires March 25, 2011 [Page 9]