PANA Working Group D. Forsberg Internet-Draft Nokia Expires: January 15, 2005 Y. Ohba (Ed.) Toshiba B. Patil Nokia H. Tschofenig Siemens A. Yegin Samsung July 17, 2004 Protocol for Carrying Authentication for Network Access (PANA) draft-ietf-pana-pana-05 Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 15, 2005. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This document defines the Protocol for Carrying Authentication for Network Access (PANA), a link-layer agnostic transport for Extensible Forsberg, et al. Expires January 15, 2005 [Page 1] Internet-Draft PANA July 2004 Authentication Protocol (EAP) to enable network access authentication between clients and access networks. PANA can carry any authentication method that can be specified as an EAP method, and can be used on any link that can carry IP. PANA covers the client-to-network access authentication part of an overall secure network access framework, which additionally includes other protocols and mechanisms for service provisioning, access control as a result of initial authentication, and accounting. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 1.1 Specification of Requirements . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . 8 3.1 Illustration of a Complete Message Sequence . . . . . . . 9 4. Protocol Details . . . . . . . . . . . . . . . . . . . . . . 11 4.1 Common Processing Rules . . . . . . . . . . . . . . . . . 11 4.1.1 Payload Encoding . . . . . . . . . . . . . . . . . . . 11 4.1.2 Transport Layer Protocol . . . . . . . . . . . . . . . 12 4.1.3 Fragmentation . . . . . . . . . . . . . . . . . . . . 12 4.1.4 Sequence Number and Retransmission . . . . . . . . . . 12 4.1.5 PANA Security Association . . . . . . . . . . . . . . 13 4.1.6 Message Authentication Code . . . . . . . . . . . . . 15 4.1.7 Message Validity Check . . . . . . . . . . . . . . . . 15 4.1.8 Error Handling . . . . . . . . . . . . . . . . . . . . 17 4.2 Discovery and Initial Handshake Phase . . . . . . . . . . 17 4.2.1 Discovery and Initial Handshake with NAP-ISP Authentication Separation . . . . . . . . . . . . . . 20 4.3 Authentication Phase . . . . . . . . . . . . . . . . . . . 21 4.4 Re-authentication . . . . . . . . . . . . . . . . . . . . 24 4.5 Termination Phase . . . . . . . . . . . . . . . . . . . . 26 4.6 Example Sequence for NAP and ISP Separate Authentications . . . . . . . . . . . . . . . . . . . . . 26 4.7 Responding to Duplicate Requests . . . . . . . . . . . . . 28 4.8 Device ID Choice . . . . . . . . . . . . . . . . . . . . . 29 4.9 Updating PaC' Address . . . . . . . . . . . . . . . . . . 29 4.10 Session Lifetime . . . . . . . . . . . . . . . . . . . . 30 4.11 Retransmission of Duplicate Answers . . . . . . . . . . 31 4.12 Mobility Handling . . . . . . . . . . . . . . . . . . . 31 4.13 Support for Separate EP . . . . . . . . . . . . . . . . 33 5. PANA Security Association Establishment . . . . . . . . . . 34 6. Message Formats . . . . . . . . . . . . . . . . . . . . . . 35 6.1 IP and UDP Headers . . . . . . . . . . . . . . . . . . . . 35 6.2 PANA Header . . . . . . . . . . . . . . . . . . . . . . . 35 6.3 AVP Header . . . . . . . . . . . . . . . . . . . . . . . . 37 6.4 PANA Messages . . . . . . . . . . . . . . . . . . . . . . 39 6.4.1 Message Specifications . . . . . . . . . . . . . . . . 39 Forsberg, et al. Expires January 15, 2005 [Page 2] Internet-Draft PANA July 2004 6.4.2 PANA-PAA-Discover (PDI) . . . . . . . . . . . . . . . 40 6.4.3 PANA-Start-Request (PSR) . . . . . . . . . . . . . . . 40 6.4.4 PANA-Start-Answer (PSA) . . . . . . . . . . . . . . . 40 6.4.5 PANA-Auth-Request (PAR) . . . . . . . . . . . . . . . 41 6.4.6 PANA-Auth-Answer (PAN) . . . . . . . . . . . . . . . . 41 6.4.7 PANA-Bind-Request (PBR) . . . . . . . . . . . . . . . 41 6.4.8 PANA-Bind-Answer (PBA) . . . . . . . . . . . . . . . . 42 6.4.9 PANA-Reauth-Request (PRAR) . . . . . . . . . . . . . . 42 6.4.10 PANA-Reauth-Answer (PRAA) . . . . . . . . . . . . . 42 6.4.11 PANA-Termination-Request (PTR) . . . . . . . . . . . 42 6.4.12 PANA-Termination-Answer (PTA) . . . . . . . . . . . 43 6.4.13 PANA-Error (PER) . . . . . . . . . . . . . . . . . . 43 6.4.14 PANA-FirstAuth-End-Request (PFER) . . . . . . . . . 43 6.4.15 PANA-FirstAuth-End-Answer (PFEA) . . . . . . . . . . 43 6.4.16 PANA-Update-Request (PUR) . . . . . . . . . . . . . 44 6.4.17 PANA-Update-Answer (PUA) . . . . . . . . . . . . . . 44 6.5 AVPs in PANA . . . . . . . . . . . . . . . . . . . . . . . 44 6.5.1 MAC AVP . . . . . . . . . . . . . . . . . . . . . . . 44 6.5.2 Device-Id AVP . . . . . . . . . . . . . . . . . . . . 45 6.5.3 Session-Id AVP . . . . . . . . . . . . . . . . . . . . 45 6.5.4 Cookie AVP . . . . . . . . . . . . . . . . . . . . . . 45 6.5.5 Protection-Capability AVP . . . . . . . . . . . . . . 45 6.5.6 Termination-Cause AVP . . . . . . . . . . . . . . . . 45 6.5.7 Result-Code AVP . . . . . . . . . . . . . . . . . . . 46 6.5.8 EAP-Payload AVP . . . . . . . . . . . . . . . . . . . 50 6.5.9 Session-Lifetime AVP . . . . . . . . . . . . . . . . . 50 6.5.10 Failed-AVP AVP . . . . . . . . . . . . . . . . . . . 50 6.5.11 NAP-Information AVP . . . . . . . . . . . . . . . . 50 6.5.12 ISP-Information AVP . . . . . . . . . . . . . . . . 50 6.5.13 Provider-Identifier AVP . . . . . . . . . . . . . . 50 6.5.14 Provider-Name AVP . . . . . . . . . . . . . . . . . 51 6.5.15 EP-Device-Id AVP . . . . . . . . . . . . . . . . . . 51 6.5.16 Key-Id AVP . . . . . . . . . . . . . . . . . . . . . 51 6.5.17 Post-PANA-Address-Configuration (PPAC) AVP . . . . . 51 6.5.18 Nonce AVP . . . . . . . . . . . . . . . . . . . . . 52 6.5.19 IP-Address AVP . . . . . . . . . . . . . . . . . . . 52 6.6 AVP Occurrence Table . . . . . . . . . . . . . . . . . . . 52 7. PANA Protocol Message Retransmissions . . . . . . . . . . . 56 7.1 Transmission and Retransmission Parameters . . . . . . . . 58 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . 59 8.1 PANA UDP Port Number . . . . . . . . . . . . . . . . . . . 59 8.2 PANA Multicast Address . . . . . . . . . . . . . . . . . . 59 8.3 PANA Header . . . . . . . . . . . . . . . . . . . . . . . 59 8.3.1 Message Type . . . . . . . . . . . . . . . . . . . . . 59 8.3.2 Flags . . . . . . . . . . . . . . . . . . . . . . . . 60 8.4 AVP Header . . . . . . . . . . . . . . . . . . . . . . . . 60 8.4.1 AVP Code . . . . . . . . . . . . . . . . . . . . . . . 60 8.4.2 Flags . . . . . . . . . . . . . . . . . . . . . . . . 61 Forsberg, et al. Expires January 15, 2005 [Page 3] Internet-Draft PANA July 2004 8.5 AVP Values . . . . . . . . . . . . . . . . . . . . . . . . 61 8.5.1 Algorithm Values of MAC AVP . . . . . . . . . . . . . 61 8.5.2 Protection-Capability AVP Values . . . . . . . . . . . 61 8.5.3 Termination-Cause AVP Values . . . . . . . . . . . . . 61 8.5.4 Result-Code AVP Values . . . . . . . . . . . . . . . . 61 8.5.5 Post-PANA-Address-Configuration AVP Values . . . . . . 62 9. Security Considerations . . . . . . . . . . . . . . . . . . 63 10. Open Issues and Change History . . . . . . . . . . . . . . . 69 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 70 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 71 12.1 Normative References . . . . . . . . . . . . . . . . . . . 71 12.2 Informative References . . . . . . . . . . . . . . . . . . 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 75 Intellectual Property and Copyright Statements . . . . . . . 77 Forsberg, et al. Expires January 15, 2005 [Page 4] Internet-Draft PANA July 2004 1. Introduction Providing secure network access service requires access control based on the authentication and authorization of the clients and the access networks. Initial and subsequent client-to-network authentication provides parameters that are needed to police the traffic flow through the enforcement points. A protocol is needed to carry authentication methods between the client and the access network. Currently there is no standard network-layer solution for authenticating clients for network access. Appendix A of [I-D.ietf-pana-requirements] describes the problem statement that led to the development of PANA. Scope of this work is identified as designing a link-layer agnostic transport for network access authentication methods. The Extensible Authentication Protocol (EAP) [RFC3748] provides such authentication methods. In other words, PANA will carry EAP which can carry various authentication methods. By the virtue of enabling transport of EAP above IP, any authentication method that can be carried as an EAP method is made available to PANA and hence to any link-layer technology. There is a clear division of labor between PANA, EAP and EAP methods. Various environments and usage models for PANA are identified in Appendix A of [I-D.ietf-pana-requirements]. Potential security threats for network-layer access authentication protocol are discussed in [I-D.ietf-pana-threats-eval]. These have been essential in defining the requirements [I-D.ietf-pana-requirements] on the PANA protocol. Note that some of these requirements are imposed by the chosen payload, EAP [RFC3748]. There are components that are part of a complete secure network solution but are outside of the PANA protocol specification, including IP address configuration, authentication method choice, filter rule installation, data traffic protection and PAA-EP protocol. These components are described in separate documents (see [I-D.ietf-pana-framework] and [I-D.ietf-pana-snmp]). 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]. Forsberg, et al. Expires January 15, 2005 [Page 5] Internet-Draft PANA July 2004 2. Terminology This section describes some terms introduced in this document: PANA Session: A PANA session begins with the initial handshake between the PANA Client (PaC) and the PANA Authentication Agent (PAA), and terminates by an authentication failure, a timeout, or an explicit termination message. A fixed session identifier is maintained throughout a session. A session cannot be shared across multiple physical network interfaces. A distinct PANA session is associated with the device identifiers of PaC and PAA. Session Identifier: This identifier is used to uniquely identify a PANA session on the PAA and PaC. It includes an identifier of the PAA, therefore it cannot be shared across multiple PAAs. It is included in PANA messages to bind the message to a specific PANA session. This bidirectional identifier is allocated by the PAA following the initial handshake and freed when the session terminates. PANA Security Association: A PANA security association is a relationship between the PaC and PAA, formed by the sharing of cryptographic keying material and associated context. Security associations are duplex. That is, one security association is needed to protect the bidirectional traffic between the PaC and the PAA. PANA Client (PaC): The client side of the protocol that resides in the host device which is responsible for providing the credentials to prove its identity for network access authorization. Device Identifier (DI): The identifier used by the network as a handle to control and police the network access of a client. Depending on the access technology, this identifier might contain any of IP address, link-layer address, switch port number, etc. of a connected device. Forsberg, et al. Expires January 15, 2005 [Page 6] Internet-Draft PANA July 2004 PANA Authentication Agent (PAA): The protocol entity in the access network side whose responsibility is to verify the credentials provided by a PANA client and grant network access service to the device associated with the client and identified by a DI. Note the authentication and authorization procedure can, according to the EAP model, be also offloaded to the backend AAA infrastructure. Enforcement Point (EP): A node on the access network where per-packet enforcement policies (i.e., filters) are applied on the inbound and outbound traffic of client devices. Information such as the DI and (optionally) cryptographic keys are provided by the PAA per client for constructing filters on the EP. Network Access Provider (NAP): A service provider that provides physical and link-layer connectivity to an access network it manages. AAA-Key: A key derived by the EAP peer and EAP server and transported to the authenticator [I-D.ietf-eap-keying]. Forsberg, et al. Expires January 15, 2005 [Page 7] Internet-Draft PANA July 2004 3. Protocol Overview The PANA protocol involves two functional entities namely the PaC and the PAA. The protocol resides above the transport layer and the details are explained in Section 4. The placement of the entities used in PANA largely depends on a selected architecture. The PAA may optionally interact with a AAA backend to authenticate the user (PaC). The EP, mentioned in the context with PANA, is a logical entity. In case that the PAA and the EP are co-located only an API is required for intercommunication instead of a separate protocol. In the case where the PAA is separated from the EP, a separate protocol will be used between the PAA and the EP for managing access control. A description of this protocol is outside the scope of this draft and is covered in [I-D.ietf-pana-snmp]. Figure 1 illustrates the interactions in a simplified manner: PaC EP PAA AAA --- --- --- --- PAA Discovery <---------------------o------------> (1) PANA Authentication AAA interaction <----------------------------------><------------> (2) Authorization <------------- (3) Figure 1: PANA Framework PANA supports authentication of a PaC using various EAP methods. The EAP method used depends on the level of security required for the EAP messaging itself. PANA does not secure the data traffic itself. However, EAP methods that enable key exchange may allow other protocols to be bootstrapped for securing the data traffic (e.g., [I-D.ietf-pana-ipsec]). From a state machine point of view, the PANA protocol consists of three phases 1. Discovery and initial handshake phase 2. Authentication phase 3. Termination phase Forsberg, et al. Expires January 15, 2005 [Page 8] Internet-Draft PANA July 2004 In the first phase, an IP address of PAA is discovered and a PANA session is established between PaC and PAA. EAP messages are exchanged and a PANA SA is established in the second phase. The PANA session as well as the PANA SA is deleted in the third phase. In addition, PANA defines the following two types of re-authentication procedures that are performed while an established PANA session exists. 1. Re-authentication based on EAP 2. Re-authentication based on PANA-Reauth exchange The former type of re-authentication is used mainly for extending authorization lifetime or for updating the cryptographic keying material of a PANA SA. The latter type of re-authentication is used mainly for maintaining the presence of the communicating peers each other so that the established PANA session can be terminated as soon as the presence of the peer is lost. 3.1 Illustration of a Complete Message Sequence A complete PANA message sequence is illustrated in Figure 2. The example assumes the following scenario: o The PaC initiates the discovery and initial handshake phase by multicasting a PANA-PAA-Discover message. The PAA responds with a PANA-Start-Request message with a cookie to be stateless in the discovery and initial handshake phase. At the end of the the discovery and initial handshake phase, the PaC sends a PANA-Start-Answer message with a cookie in response to the PANA-Start-Request. o An EAP authentication method with a single round trip is used in the authentication phase. A AAA-Key is derived from the EAP method and used for establishing a PANA SA. o At the end of the authentication phase, the PAA sends a PANA-Bind-Request message and the PaC responds with a PANA-Bind-Answer message. These messages contains a MAC AVP and a Key-Id AVP, as well as other AVPs for which usages are explained in Section 4, to securely establish a PANA session with a PANA SA. o After the PANA SA is established, all messages are integrity and replay protected with MAC AVPs. o Re-authentication based on the PANA-Reauth-Request/ PANA-Reauth exchange is performed. Forsberg, et al. Expires January 15, 2005 [Page 9] o The PaC initiates termination of the PANA session by sending a PANA-Termination-Request message. o Sequence numbers in PANA headers are not shown. PaC PAA Message[AVPs] ----------------------------------------------------- // Discovery and initial handshake phase -----> PANA-PAA-Discover <----- PANA-Start-Request[Nonce, Cookie] -----> PANA-Start-Request-Answer[Nonce, Cookie] // Authentication phase <----- PANA-Auth-Request[Session-Id, EAP] -----> PANA-Auth-Answer[Session-Id, EAP] <----- PANA-Auth-Request[Session-Id, EAP] -----> PANA-Auth-Answer[Session-Id, EAP] <----- PANA-Bind-Request[Session-Id, EAP{Success}, Device-Id, Lifetime, Protection-Cap., Key-Id, MAC] -----> PANA-Bind-Answer[Session-Id, Device-Id, Key-Id, MAC] // Re-authentication based on PANA-Reauth exchange <----- PANA-Reauth-Request[Session-Id, MAC] -----> PANA-Reauth-Answer[Session-Id, MAC] // Termination phase -----> PANA-Termination-Request[Session-Id, MAC] <----- PANA-Termination-Answer[Session-Id, MAC] Figure 2: A Complete Message Sequence Forsberg, et al. Expires January 15, 2005 [Page 10] Internet-Draft PANA July 2004 4. Protocol Details 4.1 Common Processing Rules 4.1.1 Payload Encoding The payload of any PANA message consists of zero or more AVPs (Attribute Value Pairs). A brief description of the AVPs defined in this document is listed below: o Cookie AVP: contains a random value that is used for making initial handshake robust against blind resource consumption DoS attacks. o Protection-Capability AVP: contains information which protection should be initiated after the PANA exchange (e.g., link-layer or network layer protection). o Device-Id AVP: contains a device identifier of the sender of the message. A device identifier is represented as a pair of device identifier type and device identifier value. Either a layer-2 address or an IP address is used for the device identifier value. o EP-Device-Id AVP: contains the device identifier of an EP. o EAP AVP: contains an EAP PDU. o MAC AVP: contains a Message Authentication Code that protects a PANA message PDU. o Termination-Cause AVP: contains the reason of session termination. o Result-Code AVP: contains information about the protocol execution results. o Session-Id AVP: contains the session identifier value. o Session-Lifetime AVP: contains the duration of authorized access. o Failed-AVP: contains the offending AVP that caused a failure. o NAP-Information AVP, ISP-Information AVP: contains the information on a NAP and an ISP, respectively. o Key-Id AVP: contains a AAA-Key identifier. o PPAC AVP: Post-PANA-Address-Configuration AVP. Conveys the list of IP address configuration methods available when sent by the Forsberg, et al. Expires January 15, 2005 [Page 11] Internet-Draft PANA July 2004 PAA, and the chosen method when sent by the PaC. o Nonce AVP: contains a randomly chosen value. o IP-Address AVP: contains an IP Address of a PaC. 4.1.2 Transport Layer Protocol PANA uses UDP as its transport layer protocol. The UDP port number is TBD. All messages except for PANA-PAA-Discover are always unicast. PANA-PAA-Discover MAY be unicasted when the PaC knows the IP address of the PAA. 4.1.3 Fragmentation PANA does not provide fragmentation of PANA messages. Instead, it relies on fragmentation provided by EAP methods and IP layer when needed. 4.1.4 Sequence Number and Retransmission PANA uses sequence numbers to provide ordered delivery of EAP messages. The design involves use of two sequence numbers to prevent some of the DoS attacks on the sequencing scheme. Every PANA packet includes one transmitted sequence number (tseq) and one received sequence number (rseq) in the PANA header. See [1] for detailed explanation on why two sequence numbers are needed. The two sequence number fields have the same length of 32 bits and appear in PANA header. The transmission sequence number starts from initial sequence number (ISN) and is monotonically increased by 1. This rule applies to all PANA messages but PANA-PAA-Discover. The serial number arithmetic defined in [RFC1982] is used for sequence number operation. The ISNs are exchanged between PaC and PAA during the discovery and initial handshake phase (see Section 4.2). The rules that govern the sequence numbers in other phases are described as follows. o When a message is sent, a new sequence number is placed on the tseq field of message regardless of whether it is sent as a result of retransmission or not. When a message is sent, rseq is copied from the tseq field of the last accepted message. o When a message is received, it is considered valid in terms of sequence numbers if and only if (i) its tseq is greater than the tseq of the last accepted message and (ii) its rseq falls in the range between the tseq of the last acknowledged message and the tseq of the last transmitted message. Forsberg, et al. Expires January 15, 2005 [Page 12] Internet-Draft PANA July 2004 PANA relies on EAP-layer retransmissions, or for example NAS functionality [I-D.ietf-aaa-eap], for retransmitting EAP Requests based on timer. Other PANA layer messages that require a response from the communicating peer are retransmitted based on timer at PANA-layer until a response is received (in which case the retransmission timer is stopped) or the number of retransmission reaches the maximum value (in which case the PANA session MUST be deleted immediately). For PANA-layer retransmission, the retransmission timer SHOULD be calculated as described in [RFC2988] to provide congestion control. See Section 7 for default timer and maximum retransmission count parameters. 4.1.5 PANA Security Association A PANA SA is created as an attribute of a PANA session when EAP authentication succeeds with a creation of a AAA-Key. A PANA SA is not created when the PANA authentication fails or no AAA-Key is produced by any EAP authentication method. In the case where two EAP authentications are performed in sequence in a single PANA authentication phase, it is possible that two AAA-Keys are derived. If this happens, the PANA SA MUST be generated from both AAA-Keys. When a new AAA-Key is derived as a result of EAP-based re-authentication, any key derived from the old AAA-Key MUST be updated to a new one that is derived from the new AAA-Key. In order to distinguish the new AAA-Key from old ones, one Key-Id AVP MUST be carried in PANA-Bind-Request and PANA-Bind-Answer messages or PANA-FirstAuth-End-Request and PANA-FirstAuth-End-Answer messages at the end of the EAP authentication which resulted in deriving a new AAA-Key. The Key-Id AVP is of type Unsigned32 and MUST contain a value that uniquely identifies the AAA-Key within the PANA session. The PANA-Bind-Answer message (or the PANA-FirstAuth-End-Answer message) sent in response to a PANA-Bind-Request message (or a PANA-FirstAuth-End-Request message) with a Key-Id AVP MUST contain a Key-Id AVP with the same AAA-Key identifier carried in the request. PANA-Bind-Request, PANA-Bind-Answer, PANA-FirstAuth-End-Request and PANA-FirstAuth-End-Answer messages with a Key-Id AVP MUST also carry a MAC AVP whose value is computed by using the new PANA-MAC-KEY derived from the new AAA-Key (or the new pair of AAA-Keys when the PANA_MAC_KEY is derived from two AAA-Keys). Although the specification does not mandate a particular method for calculation of Key-Id AVP value, a simple method is to use monotonically increasing numbers. The created PANA SA is deleted when the corresponding PANA session is deleted. The lifetime of the PANA SA is the same as the lifetime of the PANA session for simplicity. PANA SA attributes as well as PANA session attributes are listed Forsberg, et al. Expires January 15, 2005 [Page 13] Internet-Draft PANA July 2004 below: PANA Session attributes: * Session-Id * Device-Id of PaC * Device-Id of PAA * IP address of PaC (may be the same as the Device-Id of PaC) * IP address of PAA (may be the same as the Device-Id of PAA) * List of device identifiers of EPs * Last transmitted tseq value * Last received rseq value * Last transmitted message payload * Retransmission interval * Session lifetime * Protection-Capability * PANA SA attributes: + Nonce generated by PaC (PaC_nonce) + Nonce generated by PAA (PAA_nonce) + AAA-Key + AAA-Key Identifier + PANA_MAC_KEY The PANA_MAC_Key is used to integrity protect PANA messages and derived from AAA-Key(s). When two AAA-Keys (AAA-Key1 and AAA-Key2) are generated as a result of double EAP authentication (see Section 4.3) the compound AAA-Key can be computed as follows ('|' indicates concatenation): AAA-Key = AAA-Key1 | AAA-Key2 Forsberg, et al. Expires January 15, 2005 [Page 14] Internet-Draft PANA July 2004 The PANA_MAC_KEY is computed in the following way: PANA_MAC_KEY = The first N bits of HMAC_SHA1(AAA-Key, PaC_nonce | PAA_nonce | Session-ID) where the value of N depends on the integrity protection algorithm in use, i.e., N=160 for HMAC-SHA1. The length of AAA-Key MUST be N bits or longer. See Section Section 4.1.6 for the detailed usage of the PANA_MAC_KEY. 4.1.6 Message Authentication Code A PANA message can contain a MAC (Message Authentication Code) AVP for cryptographically protecting the message. When a MAC AVP is included in a PANA message, the value field of the MAC AVP is calculated by using the PANA_MAC_KEY in the following way: MAC AVP value = PANA_MAC_PRF(PANA_MAC_KEY, PANA_PDU) where PANA_PDU is the PANA message including the PANA header, with the MAC AVP value field first initialized to 0. PANA_MAC_PRF represents the pseudo random function corresponding to the MAC algorithm specified in the MAC AVP. In this version of draft, PANA_MAC_PRF is HMAC-SHA1. The PaC and PAA MUST use the same algorithm to calculate a MAC AVP they originate and receive. The algorithm is determined by the PAA when a PANA-Bind-Request with a MAC AVP is sent. When the PaC does not support the MAC algorithm specified in the PANA-Bind-Request message, it MUST silently discard the message. The PAA MUST NOT change the MAC algorithm throughout the continuation of the PANA session. 4.1.7 Message Validity Check When a PANA message is received, the message is considered to be invalid at least when one of the following conditions are not met: o The IP Hop Limit (or TTL) field has a value of 255, i.e., the packet could not possibly have been forwarded by a router. o Each field in the message header contains a valid value including sequence number, message length, message type, version number, flags, etc. o When a device identifier of the communication peer is bound to the PANA session, it matches the device identifier carried in MAC and/ or IP header(s), or other auxiliary indetifier provided by the Forsberg, et al. Expires January 15, 2005 [Page 15] Internet-Draft PANA July 2004 lower-layers (e.g., circuit ID). o The message type is one of the expected types in the current state. Specifically the following messages are unexpected and invalid: * In discovery and initial handshake phase: + PANA-Termination-Request and PANA-Reauth-Request. + PANA-Bind-Request. + PANA-Update-Request. * In authentication phase: + PANA-PAA-Discover. + PANA-Termination-Request and PANA-Reauth-Request. + PANA-Update-Request. + PANA-Start-Request after a PaC receives the first valid PANA-Auth-Request. * After successful PANA authentication: + PANA-Start-Request as well as a non-duplicate PANA-Bind-Request (see section Section 4.7 for definition of duplicate requests). + PANA-PAA-Discover without a Session-Id AVP. * In termination phase: + PANA-PAA-Discover. + All requests but PANA-Termination-Request. o The message payload contains a valid set of AVPs allowed for the message type and there is no missing AVP that needs to be included in the payload. o Each AVP is decoded correctly. o When a MAC AVP is included, the AVP value matches the MAC value computed against the received message. Forsberg, et al. Expires January 15, 2005 [Page 16] o When a Device-Id AVP is included, the AVP is valid if the device identifier type contained in the AVP is supported (this check is for both PaC and PAA) and is the requested one (this check is for PAA only) and the device identifier value contained in the AVP matches the value extracted from the lower-layer encapsulation header corresponding to the device identifier type contained in the AVP. Note that a Device-Id AVP carries the PaC's device identifier in messages from PaC to PAA and PAA's device identifier in messages from PAA to PaC. Invalid messages MUST be discarded in order to provide robustness against DoS attacks. In addition, a non-acknowledged error notification message MAY be returned to the sender. See Section 4.1.8 for details. 4.1.8 Error Handling PANA-Error message MAY be sent by either PaC or PAA when a badly formed PANA message is received or in case of other errors. If the cause of this error message was a request message (e.g., PANA-PAA-Discover or *-Request), then the request MAY be retransmitted immediately without waiting for its retransmission timer to go off. If the cause of the error was a response message, the receiver of the PANA-Error message SHOULD NOT resend the same response until it receives the next request. To defend against DoS attacks a timer MAY be used. One (1) error notification is sent to each different sender each N seconds. N is a configurable parameter. When an error message is sent unprotected with MAC AVP and the lower-layer is insecure, the error message is treated as an informational message. The receiver of such an error message MUST NOT change its state unless the error persists and the PANA session is not making any progress. 4.2 Discovery and Initial Handshake Phase When a PaC attaches to a network, and knows that it has to discover a PAA, it SHOULD send a PANA-PAA-Discover message to a well-known link local multicast address (TBD) and UDP port (TBD). The PANA PAA discovery assumes that PaC and PAA are one hop away from each other. If the PaC knows the IP address of the PAA (based on pre-configuration), it MAY unicast the PANA discovery message to that address. The PAA SHOULD respond to the PANA-PAA-Discover message with a PANA-Start-Request message. When the PAA receives such a request, or upon receiving some lower layer indications of a new PaC, the PAA SHOULD unicast a PANA-Start-Request message. Forsberg, et al. Expires January 15, 2005 [Page 17] Internet-Draft PANA July 2004 There can be multiple PAAs on the link. The authentication and authorization result does not depend on which PAA is chosen by the PaC. By default the PaC MAY choose the PAA that sent the first response. The PaC MAY also choose to start sending packets before getting authenticated. In that case, the network may detect this and the PAA MAY send an unsolicited PANA-Start-Request message to the PaC in addition to filtering the unauthorized traffic. The EP is the node that can detect such activity. The PAA-to-EP protocol MAY be used for this purpose. A PANA-Start-Request message MAY carry a Cookie AVP that contains a cookie. The rseq field of the header is set to zero (0). The tseq field of the header contains the initial sequence number. The cookie is used for preventing the PAA from resource consumption DoS attacks by blind attackers. The cookie is computed in such a way that it does not require any per-session state maintenance on the PAA in order to verify the cookie returned in a PANA-Start-Answer message. The exact algorithms and syntax used for generating cookies does not affect interoperability and hence is not specified here. An example algorithm is described below. Cookie = | HMAC_SHA1( , ) where is a randomly generated secret known only to the PAA, is an index used for choosing the secret for generating the cookie and '|' indicates concatenation. The secret-version should be changed frequently enough to prevent replay attacks. The secret key is valid for a certain time frame. When the PAA receives the PANA-Start-Answer message from the PaC, it verifies the cookie. The cookie is considered as valid if the received cookie has the expected value. If the computed cookie is valid, the protocol enters the authentication phase. Otherwise, it MUST silently discard the received message. Initial EAP Request MAY be optionally carried by the PANA-Start-Request (as opposed to by a later PANA-Auth-Request) message in order to reduce the number of round-trips. This optimization SHOULD NOT be used if the PAA discovery is desired to be stateless. Protection-Capability and Post-PANA-Address-Configuration AVPs MAY be optionally included in the PANA-Start-Request in order to indicate required and available capabilities for the network access. These AVPs MAY be used by the PaC for assessing the capability match even Forsberg, et al. Expires January 15, 2005 [Page 18] Internet-Draft PANA July 2004 before the authentication takes place. But these AVPs are provided during the insecure discovery phase, there are certain security risks involved in using the provided information. See Section 9 for further discussion on this. If the initial EAP Request message is carried in the PANA-Start-Request message, an EAP Response message MUST be carried in the PANA-Start-Answer message returned to the PAA. In any case, PANA MUST NOT generate an EAP message on behalf of EAP peer or EAP (pass-through) authenticator. The PANA-Start-Request/Answer exchange is needed before entering authentication phase even when the PaC is pre-configured with PAAs IP address and the PANA-PAA-Discover message is unicast. A Nonce AVP MUST be included in PANA-Start-Request and PANA-Start-Answer messages. A PANA-Start-Request message that carries a Cookie AVP is never retransmitted. A PANA-Start-Request message that does not carry a Cookie AVP is retransmitted based on timer. A PANA-Start-Answer message that carries a Cookie AVP is retransmitted based on timer. A PANA-Start-Answer message that does not carry a Cookie AVP is never retransmitted based on timer. It is possible that both PAA and PaC initiate the discovery and initial handshake procedure at the same time, i.e., the PAA sends a PANA-Start-Request message while the PaC sends a PANA-PAA-Discover message. To resolve the race condition, the PAA SHOULD silently discard the PANA-PAA-Discover message received from the PaC after it has sent a PANA-Start-Request message with creating a state (i.e., no Cookie AVP included) for the PaC. In this case PAA will retransmit PANA-Start-Request based on a timer, if PaC doesn't respond in time (message was lost for example). If PAA had sent stateless PANA-Start-Request message (i.e., a Cookie AVP was included), then it SHOULD answer to the PANA-PAA-Discover message. Figure 3 shows an example sequence for the discovery and initial handshake phase when a PANA-PAA-Discover message is sent by a PaC. Figure 4 shows an example sequence for the discovery and initial handshake phase that is triggered by data traffic. Forsberg, et al. Expires January 15, 2005 [Page 19] Internet-Draft PANA July 2004 PaC PAA Message(tseq,rseq)[AVPs] ------------------------------------------------------ -----> PANA-PAA-Discover(0,0) <----- PANA-Start-Request(x,0)[Nonce, Cookie] -----> PANA-Start-Answer(y,x)[Nonce, Cookie] (continued to authentication phase) Figure 3: Example Sequence for Discovery and Initial Handshake Phase when PANA-PAA-Discover is sent by PaC PaC EP PAA Message(tseq,rseq)[AVPs] ------------------------------------------------------ ---->o (Data packet arrival or L2 trigger) ------> PAA-to-EP protocol, or another mechanism <------------ PANA-Start-Request(x,0)[Nonce, Cookie] ------------> PANA-Start-Answer(y,x)[Nonce, Cookie] (continued to authentication phase) Figure 4: Example Sequence for Discovery and Initial Handshake when discovery is triggered by data traffic 4.2.1 Discovery and Initial Handshake with NAP-ISP Authentication Separation In the discovery and initial handshake phase, a PAA MAY enable NAP-ISP authentication separation ([I-D.ietf-pana-framework]) by setting the S-flag of the message header of the PANA-Start-Request. Also, the PANA-Start-Request MAY contain zero or one NAP-Information AVP and zero or more ISP-Information AVPs to advertise the information on the NAP and/or ISPs. When a PaC receives the PANA-Start-Request message in response to the PANA-PAA-Discover message, it responds with a PANA-Start-Answer message if it wishes to enter the authentication phase. The PANA-Start-Answer message contains the initial sequence numbers in the tseq and rseq fields of the PANA header, a copy of the received Cookie (if any) as the PANA payload. If the S-flag of the received PANA-Start-Request message is not set, PaC MUST NOT set the S-flag in the PANA-Start-Answer message sent back to the PAA. In this case, PaC MAY indicate its choice of ISP by including an ISP-Information AVP in the PANA-Start-Answer message. When a AAA backend is used, the identity of the destination AAA server or realm MUST be determined based on the explicitly chosen Forsberg, et al. Expires January 15, 2005 [Page 20] Internet-Draft PANA July 2004 ISP. When the ISP-Information AVP is not present, the access network MAY rely on the client identifier carried in the EAP authentication method to make this determination. If the S-flag of the received PANA-Start-Request message is set, PaC can indicate its desire to perform separate EAP authentication for NAP and ISP by setting the S-flag in the PANA-Start-Answer message. If the S-flag in the PANA-Start-Answer message is not set, only one authentication is performed and the processing occurs as described in Section 4.2. If the S-flag in the PANA-Start-Answer message is set, the determination of the destination AAA server or realm for ISP authentication is performed as described earlier. In addition, where backend AAA servers are used for NAP authentication, the NAP is considered the ultimate AAA realm, and the destination AAA server for this authentication is determined entirely by the local configuration on the access server hosting PAA (NAS). The PaC can choose an ISP and contain an ISP-Information AVP for the chosen ISP in a PANA-Start-Answer message even when there is no ISP-Information AVP contained in the PANA-Start-Request message. When the S-flag is set in a PANA-Start-Request message, the initial EAP Request MUST NOT be carried in the PANA-Start-Request message. (If the initial EAP Request were contained in the PANA-Start-Request message during the S-flag negotiation, the PaC cannot tell whether the EAP Request is for NAP authentication or ISP authentication.) 4.3 Authentication Phase The main task in authentication phase is to carry EAP messages between PaC and PAA. EAP Request messages are carried in PANA-Auth-Request messages and optionally carried in PANA-Start-Request messages. EAP Response messages are carried in PANA-Auth-Answer messages and optionally carried in PANA-Start-Answer messages. When an EAP Success/Failure message is sent from a PAA, the message is carried in a PANA-Bind-Request (PBR) or PANA-FirstAuth-End-Request (PFER) message. The PANA-FirstAuth-End-Reques message MUST be used at the end of the first EAP when the PaC and PAA have negotiated during the discovery and initial handshake phase to perform separate NAP and ISP authentications in a single PANA authentication phase. Otherwise, the PANA-Bind-Request message MUST be used. The PANA-Bind-Request and PANA-FirstAuth-End-Request messages MUST be acknowledged with a PANA-Bind-Answer (PBA) and a PANA-FirstAuth-End-Answer (PFEA) messages, respectively. Figure 5 shows an example sequence for the authentication phase without separating NAP and ISP authentications. Forsberg, et al. Expires January 15, 2005 [Page 21] Internet-Draft PANA July 2004 PaC PAA Message(tseq,rseq)[AVPs] ------------------------------------------------- (continued from discovery and initial handshake phase) <----- PANA-Auth-Request(x+1,y)[Session-Id, EAP{Request}] -----> PANA-Auth-Answer(y+1,x+1)[Session-Id, EAP{Response}] . . <----- PANA-Auth-Request (x+2,y+1)[Session-Id, EAP{Request}] -----> PANA-Auth-Answer (y+2,x+2)[Session-Id, EAP{Response}] <----- PANA-Bind-Request(x+3,y+2) [Session-Id, EAP{Success}, Device-Id, Lifetime, Protection-Cap., PPAC, MAC] -----> PANA-Bind-Answer(y+3,x+3) [Session-Id, Device-Id, PPAC, MAC] Figure 5: Example Sequence in Authentication Phase When the PaC and PAA have negotiated during the discovery and initial handshake phase to perform separate NAP and ISP authentications, the S-flag of PANA-Auth-Request and PANA-Auth-Answer messages MUST be set. Otherwise, the S-flag MUST NOT be set. When separate NAP and ISP authentications are performed, the PAA determines the execution order of NAP authentication and ISP authentication. In this case, the PAA can indicate which EAP authentication is currently occurring by using N-flag in the PANA message header. When NAP authentication is performed, the N-flag MUST be set. When ISP authentication is performed, the N-flag MUST NOT be set. The N-flag MUST NOT be set when S-flag is not set. When separate NAP and ISP authentications are performed, if the first EAP authentication has failed, the PAA can choose not to perform the second EAP authentication by clearing the S-flag of the PANA-FirstAuth-End-Request message. In this case, the S-flag of the PANA-FirstAuth-End-Answer message sent by the PaC MUST be cleared. If the S-flag of the PANA-FirstAuth-End-Request message is set when the first EAP authentication has failed, the PaC can choose not to perform the second EAP authentication by clearing the S-flag of the PANA-FirstAuth-End-Answer message. If the first EAP authentication failed and the S-flag is not set in the PANA-FirstAuth-End-Answer message as a result of those operations, the PANA session MUST be immediately deleted. Otherwise, the second EAP authentication MUST be performed. Currently, use of multiple EAP methods in PANA is designed only for NAP-ISP authentication separation. It is not for arbitrary EAP method sequencing, or giving the PaC another chance when an authentication method fails. The NAP and ISP authentication are Forsberg, et al. Expires January 15, 2005 [Page 22] Internet-Draft PANA July 2004 considered completely independent. Presence or success of one should not effect the other. Making a network access authorization decision based on the success or failure of each authentication is a network policy issue. When an EAP method that is capable of deriving keys is used during the authentication phase and the keys are successfully derived, the PANA-FirstAuth-End-Request and PANA-FirstAuth-End-Answer and/or PANA-Bind-Request and PANA-Bind-Answer messages, and all subsequent PANA messages MUST contain a MAC AVP. When separate NAP and ISP authentications are performed and the lower-layer is insecure, the two EAP methods MUST be capable of deriving keys. In this case, if the first EAP authentication is successful, the PANA-FirstAuth-End-Request and PANA-FirstAuth-End-Answer messages as well as PANA-Auth-Request and PANA-Auth-Answer messages in the second EAP authentication MUST be protected with the key derived from the AAA-Key for the first EAP authentication. The PANA-Bind-Request and PANA-Bind-Answer messages and all subsequent PANA messages MUST be protected either with the AAA-Key for the first EAP authentication if the first EAP authentication succeeds and the second EAP authentication fails, or with the AAA-Key for the second EAP authentication if the first EAP authentication fails and the second EAP authentication succeeds, or with the compound AAA-Key derived from the two AAA-Keys, one for the first EAP authentication and the other from the second EAP authentication, if both the first and second EAP authentications succeed. The PANA-Bind-Request and the PANA-Bind-Answer message exchange is also used for binding device identifiers of the PaC and the PAA to the PANA SA when the identifiers are either IP or MAC addresses. To achieve this, the PANA-Bind-Request and the PANA-Bind-Answer SHOULD contain a device identifier of the PAA and the PaC, respectively, in a Device-Id AVP. Device identifier exchange that is protected by a MAC AVP prevents man-in-the-middle attacks. The PaC MUST use the same type of device identifier as contained in the PANA-Bind-Request message. The PANA-Bind-Request message MAY also contain a Protection-Capability AVP to indicate if link-layer or network-layer ciphering should be initiated after PANA. No link layer or network layer specific information is included in the Protection-Capability AVP. When the information is preconfigured on the PaC and the PAA this AVP can be omitted. It is assumed that at least PAA is aware of the security capabilities of the access network. The PANA protocol does not specify how the PANA SA and the Protection-Capability AVP will be used to provide per-packet protection for data traffic. Additionally, PANA-Bind-Request MUST include a Forsberg, et al. Expires January 15, 2005 [Page 23] Internet-Draft PANA July 2004 Post-PANA-Address-Configuration AVP, which helps PAA to inform PaC about whether a new IP address MUST be configured and the available methods to do so. PaC MUST include a PPAC AVP in order to indicate its choice of method when there is a match between the methods offered by the PAA and the methods available on the PaC. When there is no match, a PPAC AVP MUST NOT be included and the Result-Code AVP MUST be set to PANA_PPAC_CAPABILITY_UNSUPPORTED in the PANA-Bind-Answer message. PANA-Bind-Request and PANA-Bind-Answer messages MUST be retransmitted based on the retransmission rule described in Section 4.1.4. EAP authentication can fail at a pass-through authenticator without sending an EAP-Failure message [I-D.ietf-eap-statemachine]. When this occurs, the PAA SHOULD send a PANA-Error message to the PaC with using PANA_UNABLE_TO_COMPLY result code. The PaC SHOULD ignore the message unless it is secured by PANA or lower layer. In any case, a more appropriate way is to rely on a timeout on the PaC. There is a case where EAP authentication succeeds with producing an EAP-Success message but network access authorization fails due to, e.g., authorization rejected by a AAA proxy or authorization locally rejected by a PAA. When this occurs, the PAA MUST send PANA-Bind-Request with a result code PANA_AUTHORIZATION_REJECTED. If a AAA-Key is established between PaC and PAA by the time when the EAP-Success is generated by the EAP server (this is the case when the EAP method provides protected success indication), the this PANA-Bind message exchange MUST be protected with a MAC AVP and with carrying a Key-Id AVP. The AAA-Key and the PANA session MUST be deleted after the PANA-Bind message exchange. 4.4 Re-authentication There are two types of re-authentication supported by PANA. The first type of re-authentication is based on EAP by entering an authentication phase. In this case, some or all message exchanges for discovery and initial handshake phase MAY be omitted in the following way. When a PaC wants to initiate EAP-based re-authentication, it sends a unicast PANA-PAA-Discovery message to the PAA. This message MUST contain a Session-Id AVP which is used for identifying the PANA session on the PAA. If the PAA already has an established PANA session for the PaC with the matching identifier, it sends a PANA-Auth-Request message containing the same identifier to start an authentication phase. If the PAA can not recognize the session identifier, it proceeds with regular authentication by sending back PANA-Start-Request. When the PAA initiates EAP-based re-authentication, it sends a PANA-Auth-Request message containing Forsberg, et al. Expires January 15, 2005 [Page 24] Internet-Draft PANA July 2004 the session identifier for the PaC to enter an authentication phase. PAA SHOULD initiate EAP authentication before the current session lifetime expires. In both cases, the tseq and rseq values are inherited from the previous (re-)authentication. For any EAP-based re-authentication, if there is an established PANA SA, PANA-Auth-Request and PANA-Auth-Answer messages MUST be protected by adding a MAC AVP to each message. Any subsequent EAP-based authentication MUST be performed with the same ISP and NAP that was selected during the initial authentication. An example sequence for the EAP-based re-authentication initiated by a PaC is shown in Figure 6. PaC PAA Message ------------------------------------------------------ -----> PANA-PAA-Discover(0,0)[Session-Id] <----- PANA-Auth-Request(p,q)[Session-Id, EAP, MAC] -----> PANA-Auth-Answer(q+1,p)[Session-Id, EAP, MAC] <----- PANA-Auth-Request(p+1,q+1)[Session-Id, EAP, MAC] -----> PANA-Auth-Answer(q+2,p+1)[Session-Id, EAP, MAC] <----- PANA-Bind-Request(p+2,q+2) [Session-Id, EAP{Success}, Device-Id, Key-Id, Lifetime, Protection-Cap., PPAC, MAC] -----> PANA-Bind-Answer(q+3,p+2) [Session-Id, Device-Id, Key-Id, PPAC, MAC] Figure 6: Example Sequence for EAP-based re-authentication initiated by PaC The second type of re-authentication is based on a single protected message exchange without entering the authentication phase. PANA-Reauth-Request and PANA-Reauth-Answer messages are used for this purpose. If there is an established PANA session, both the PaC and the PAA are allowed to send a PANA-Reauth-Request message to the communicating peer whenever they need to make sure the availability of the session on the peer and expect the peer to return a PANA-Reauth-Answer message. Both PANA-Reauth-Request and PANA-Reauth-Answer messages MUST be protected with a MAC AVP when a PANA SA is available. Implementations MUST limit the rate of performing re-authentication for both types of re-authentication. The PaC and the PAA can handle rate limitation on their own, they do not have to perform any coordination with each other. There is no negotiation of timers for this purpose. Figure 7 and Figure 8 show re-authentication procedures based on PANA-Reauth exchange initiated by a PaC and a PAA, respectively. Forsberg, et al. Expires January 15, 2005 [Page 25] Internet-Draft PANA July 2004 PaC PAA Message(tseq,rseq)[AVPs] ------------------------------------------------------ -----> PANA-Reauth-Request(q,p)[Session-Id, MAC] <----- PANA-Reauth-Answer(p+1,q)[Session-Id, MAC] Figure 7: Example Sequence for PaC-initiated second type Re-authentication PaC PAA Message(tseq,rseq)[AVPs] ------------------------------------------------------ <----- PANA-Reauth-Request(p,q)[Session-Id, MAC] -----> PANA-Reauth-Answer(q+1,p)[Session-Id, MAC] Figure 8: Example Sequence for PAA-initiated second type Re-authentication 4.5 Termination Phase A procedure for explicitly terminating a PANA session can be initiated either from PaC (i.e., disconnect indication) or from PAA (i.e., session revocation). The PANA-Termination-Request and the PANA-Termination-Answer message exchanges are used for disconnect indication and session revocation procedures. The reason for termination is indicated in the Termination-Cause AVP. When there is an established PANA SA established between the PaC and the PAA, all messages exchanged during the termination phase MUST be protected with a MAC AVP. When the sender of the PANA-Termination-Request receives a valid acknowledgment, all states maintained for the PANA session MUST be deleted immediately. PaC PAA Message(tseq,rseq)[AVPs] ------------------------------------------------------ -----> PANA-Termination-Request(q,p)[Session-Id, MAC] <----- PANA-Termination-Answer(p+1,q)[Session-Id, MAC] Figure 9: Example Sequence for Session Termination 4.6 Example Sequence for NAP and ISP Separate Authentications A PANA message sequence where NAP and ISP separate authentications occur is illustrated in Figure 10. The example assumes the following Forsberg, et al. Expires January 15, 2005 [Page 26] Internet-Draft PANA July 2004 scenario: o The PaC multicasts PANA-PAA-Discover message. o The ISNs used by the PAA and the PaC are x and y, respectively. o The PAA offers NAP and ISP separate authentications, as well as a choice of ISP from "ISP1" and "ISP2". The PaC accepts the offer from PAA, with choosing "ISP1" as the ISP. o An EAP sequence for NAP authentication and an EAP sequence for ISP authentication is performed in this order in authentication phase. o An EAP authentication method with a single round trip is used in each EAP sequence. o Two AAA-Keys are derived from the EAP authentication methods, i.e., AAA-Key1 and AAA-Key2. The PANA_MAC_KEY is first derived from the AAA-Key1 upon the completion of the first EAP, and then it is updated so that it is derived from both AAA-Key1 and AAA-Key2 upon the completion of the second EAP. o After a PANA SA is established, all messages are integrity and replay protected with MAC AVPs. o Re-authentication based on the PANA-Reauth exchange is performed. o Re-authentication and termination phase are not shown. o Session-Id AVP is not shown. Forsberg, et al. Expires January 15, 2005 [Page 27] Internet-Draft PANA July 2004 PaC PAA Message(tseq,rseq)[AVPs] ----------------------------------------------------- // Discovery and initial handshake phase -----> PANA-PAA-Discover(0,0) <----- PANA-Start-Request(x,0) // S-flag set [Nonce, Cookie, ISP-Information("ISP1"), ISP-Information("ISP2"), NAP-Information("MyNAP")] -----> PANA-Start-Request-Answer(y,x) // S-flag set [Nonce, Cookie, ISP-Information("ISP1")]// PaC chooses "ISP1" // Authentication phase <----- PANA-Auth-Request(x+1,y)[EAP] // NAP authentication // S- and N-flags set -----> PANA-Auth-Answer(y+1,x+1)[EAP] // S- and N-flags set <----- PANA-Auth-Request(x+2,y+1)[EAP] // S- and N-flags set -----> PANA-Auth-Answer(y+2,x+2)[EAP] // S- and N-flags set <----- PANA-FirstAuth-End-Request(x+3,y+2) // S- and N-flags set [EAP{Success}, Key-Id, MAC] -----> PANA-FirstAuth-End-Answer(y+3,x+3) // S- and N-flags set [Key-Id, MAC] <----- PANA-Auth-Request(x+3,y+4)[EAP, MAC]// ISP authentication // S-flag set -----> PANA-Auth-Answer(y+4,x+4)[EAP, MAC] // S-flag set <----- PANA-Auth-Request(x+4,y+5)[EAP, MAC]// S-flag set -----> PANA-Auth-Answer(y+5,x+5)[EAP, MAC] // S-flag set <----- PANA-Bind-Request(x+5,y+6) // S-flag set [EAP{Success}, Device-Id, Key-Id, Lifetime, Protection-Cap., PPAC, MAC] -----> PANA-Bind-Answer(y+6,x+5) // S-flag set [Device-Id, Key-Id, PPAC, MAC] Figure 10: A Complete Message Sequence for NAP and ISP Separate Authentications 4.7 Responding to Duplicate Requests Since PANA is designed over UDP, an answer as well as a request can be lost. In order to provide robustness against possible loss of synchronization between a PaC and a PAA, the responder MAY send a duplicate answer to a request that it had just answered. The only difference between two consecutive duplicate requests are the sequence numbers and the content of MAC AVP (when present). o When a PaC receives a duplicate PANA-Start-Request message for which it has already answered, it SHOULD send a duplicate Forsberg, et al. Expires January 15, 2005 [Page 28] Internet-Draft PANA July 2004 PANA-Start-Answer message until it receives a valid PANA-Auth-Request message. o When a PaC receives a duplicate PANA-FirstAuth-End-Request message for which it has already answered, it SHOULD send a duplicate PANA-FirstAuth-End-Answer message until it receives a valid PANA-Auth-Request message for the second EAP authentication. o When a PaC receives a duplicate PANA-Bind-Request message for which it has already answered, it SHOULD send a duplicate PANA-Bind-Answer message until it receives some hint provided outside the PANA protocol (e.g., receipt of a secure association protocol message from an EP or receipt of data traffic) indicating that the PAA has received a PANA-Bind-Answer message. o When a PaC or a PAA receives a duplicate PANA-Termination-Request message for which it has already answered, it MAY send a duplicate PANA-Termination-Answer message in accordance with the timers described in Section 7. 4.8 Device ID Choice The device identifier used in the context of PANA can be an IP address, a MAC address, or an identifier that is not carried in data packets but has local significance in identifying a connected host (e.g., circuit ID). The last type of identifiers are commonly used in physically secured point-to-point links where MAC addresses are not available. It is assumed that the PAA knows the link type and the security mechanisms being provided or required on the access network (e.g., based on physical security, link-layer ciphers enabled before or after PANA, or IPsec). Based on that information, the PAA can decide what type of device ID will be used when running PANA with the client. When IPsec-based security [I-D.ietf-pana-ipsec] is the choice of access control, the PAA SHOULD provide an IP address as device ID, and expect the PaC to provide its IP address in return. In case IPsec is not used, MAC addresses are used as device IDs when available. If non-IPsec access control is enabled, and a MAC address is not available, device ID exchange does not occur within PANA. Instead, peers rely on lower-layers to provide locally-significant identifiers along with received PANA packets. 4.9 Updating PaC' Address A PaC's IP address can change in certain situations. For example, the PANA framework [I-D.ietf-pana-framework] describes a case in which a PaC replaces a pre-PANA address (PRPA) with a post-PANA Forsberg, et al. Expires January 15, 2005 [Page 29] Internet-Draft PANA July 2004 address (POPA), and the PaC and PAA create host routes to each other in order to maintain on-link communication based on the POPA. The PAA needs to be notified about the change of PaC address. After the PaC has changed its address, it MUST send a PANA-Update-Request message to the PAA. The message MUST carry the new PaC address in an IP-Address AVP. If the address contained in the request is invalid, the PAA MUST send a PANA-Error message with the result code PANA_INVALID_IP_ADDRESS. Otherwise, the PAA MUST update the PANA session with the new PaC address and return a PANA-Update-Answer message. If there is an established PANA SA, both PANA-Update-Request and PANA-Update-Answer messages MUST be protected with a MAC AVP. 4.10 Session Lifetime The authentication phase determines the PANA session lifetime when the network access authorization succeeds. The Session-Lifetime AVP MAY be optionally included in the PANA-Bind-Request message to inform PaC about the valid lifetime of the PANA session. It MUST be ignored when included in other PANA messages. When there are multiple EAP authentication taking place, this AVP SHOULD be included after the final authentication. The lifetime is a non-negotiable parameter that can be used by PaC to manage PANA-related state. PaC does not have to perform any actions when the lifetime expires, other than optionally purging local state. PAA SHOULD initiate EAP authentication before the current session lifetime expires. PaC and PAA MAY optionally rely on lower-layer indications to expedite the detection of a disconnected peer. Availability and reliability of such indications depend on the specific access technologies. PANA peer can use PANA-Reauth-Request message to verify the disconnection before taking an action. The session lifetime parameter is not related to the transmission of PANA-Reauth-Request messages. These messages can be used for asynchronously verifying the liveness of the peer and enabling mobility optimizations. The decision to send PANA-Reauth-Request message is taken locally and does not require coordination between the peers. When separate EAP authentications are performed for ISP and NAP in a single PANA session, it is possible that different authorization lifetime values are associated with the two authentications. In this case, the smaller authorization lifetime value MUST be used for calculating the PANA Session-Lifetime value. As a result, when Forsberg, et al. Expires January 15, 2005 [Page 30] Internet-Draft PANA July 2004 EAP-based re-authentication occurs, both NAP and ISP authentications will be performed in the same re-authentication procedure. 4.11 Retransmission of Duplicate Answers Since PANA is designed over UDP, an answer as well as a request can be lost. In order to improve robustness against possible loss of synchronization between a PaC and a PAA, the responder of a request MAY send a duplicate answer to a duplicate request for which already answered (as well as a fresh answer to a new request if any). In PANA, a duplicate PANA-Start-Request or PANA-Start-Answer message has the same contents as the original request or answer, respectively. A duplicate request other than PANA-Start-Request has the same contents as the original request except for the transmission sequence number and a MAC AVP (if any). Also, a duplicate answer other than PANA-Start-Answer has the same contents as the original answer except for the transmission and receiving sequence numbers and a MAC AVP (if any). Retransmission of a duplicate answer in response to a duplicate request occurs in the following ways. o When a PaC receives a duplicate PANA-Start-Request message for which it has already answered, it MAY send a duplicate PANA-Start-Answer message until it receives a valid PANA-Auth-Request message. o When a PaC receives a duplicate PANA-FirstAuth-End-Request message for which it has already answered, it MAY send a duplicate PANA-FirstAuth-End-Answer message until it receives a valid PANA-Auth-Request message for the second EAP authentication. o When a PaC receives a duplicate PANA-Bind-Request message for which it has already answered, it MAY send a duplicate PANA-Bind-Answer message until it receives some hint provided outside the PANA protocol (e.g., receipt of a secure association protocol message from an EP or receipt of data traffic) indicating that the PAA has received a PANA-Bind-Answer message. o When a PaC or a PAA receives a duplicate PANA-Termination-Request message for which it has already answered, it MAY send a duplicate PANA-Termination-Answer message for a while before deleting the PANA session. The period to send duplicate PANA-Termination-Answer messages may be a configurable parameter. 4.12 Mobility Handling A mobile PaC's network access authentication performance can be enhanced by deploying a context-transfer-based mechanism, where some Forsberg, et al. Expires January 15, 2005 [Page 31] Internet-Draft PANA July 2004 session attributes are transferred from the previous PAA to the new one in order to avoid performing a full EAP authentication (reactive approach). Additional mechanisms that are based on the proactive AAA state establishment at one or more candidate PAAs may be developed in the future [I-D.irtf-aaaarch-handoff]. The details of a context-transfer-based mechanism is provided in this section. Upon changing its point of attachment, a PaC that wants to quickly resume its ongoing PANA session without running EAP MAY send its unexpired PANA session identifier in its PANA-Start-Answer message. Along with the Session-Id AVP, a MAC AVP MUST be included in this message. The MAC AVP is computed by using the PANA_MAC_KEY shared between the PaC and its previous PAA that has an unexpired PANA session with the PaC. This action signals PaC's desire to perform the mobility optimization. In the absence of a Session-Id AVP in this message, the PANA session takes its usual course (i.e., EAP-based authentication is performed). If a PAA receives a session identifier in the PANA-Start-Answer message, and it is configured to enable this optimization, it SHOULD retrieve the PANA session attributes from the previous PAA. Current PAA determines the identity of the previous PAA by looking at the DiameterIdentity part of the PANA session identifier. The MAC AVP can only be verified by the previous PAA, therefore a copy of the PANA message SHOULD be provided to the previous PAA. The mechanism required to send a copy of the PANA-Start-Answer message from current PAA to the previous PAA, and retrieve the session attributes is outside the scope of PANA protocol. Seamoby Context Transfer Protocol [I-D.ietf-seamoby-ctp] might be useful for this purpose. When the previous or current PAA is not configured to enable this optimization, the current PAA can not retrieve the PANA session attributes, or the PANA session has already expired (i.e., session lifetime is zero), the PAA MUST send the PANA-Auth-Request message with a new session identifier and let the PANA exchange take its usual course. This action will engage EAP-based authentication and create a fresh PANA session from scratch. In case the current PAA can retrieve the on-going PANA session attributes from the previous PAA, the PANA session continues with a PANA-Bind exchange. As part of the context transfer, an intermediate AAA-Key material is provided by the previous PAA to the current PAA. AAA-Key-int = The first N bits of HMAC-SHA1(AAA-Key, DiameterIdentity | Session-ID) Forsberg, et al. Expires January 15, 2005 [Page 32] Internet-Draft PANA July 2004 The value of N depends on the integrity protection algorithm in use, i.e., N=160 for HMAC-SHA1. DiameterIdentity is the identifier of the current PAA. Session-ID is the identifier of the PaC's PANA session with the previous PAA. The current PAA and PaC compute the new AAA-Key by using the nonce values and the AAA-Key-int. AAA-Key-new = The first N bits of HMAC-SHA1(AAA-Key-int, PaC_nonce | PAA_nonce) New PANA_MAC_KEY is computed based on the algorithm described in Section 4.1.5, by using the new AAA-Key and the new Session-ID assigned by the current PAA. The MAC AVP contained in the PANA-Bind-Request and PANA-Bind-Answer messages MUST be generated and verified by using the new PANA_MAC_KEY. The Session-ID AVP MUST include a new session identifier assigned by the current PAA. A new PANA session is created upon successful completion of this exchange. Note that correct operation of this optimization relies on many factors, including applicability of authorization state from one network attachment to another. [I-D.ietf-eap-keying] identifies this operation as "fast handoff" and provides deployment considerations. Operators are recommended to take those guidelines into account when using this optimization in their networks. 4.13 Support for Separate EP PANA allows the PAA and the EP to be separate entities. In this case, if data traffic protection needs to be initiated after successful PANA authentication phase, the PaC needs to know the device identifier of EP(s) so that it is able to establish a security association with each EP to protect data traffic. To this end, when a Protection-Capability AVP with either L2_PROTECTION or IPSEC_PROTECTION in the AVP payload is carried in a PANA-Bind-Request message and if there is an EP that has a different device identifier than that of the PAA, one or more EP-Device-Id AVPs MUST also be carried in the PANA-Bind-Request message. In this case, if one EP has the same device identifier as the PAA, an EP-Device-Id AVP that contains the device identifier of the EP (i.e., the PAA) MUST also be included in the PANA-Bind-Request. Aside from provisioning the EP, the same PAA-to-EP protocol MAY be used for triggering the PAA upon detecting the need to authenticate a new client. Forsberg, et al. Expires January 15, 2005 [Page 33] Internet-Draft PANA July 2004 5. PANA Security Association Establishment When PANA is used over an already established secure channel, such as physically secured wires or ciphered link-layers, we can reasonably assume that man-in-the-middle attacks or service theft is not possible. See [I-D.ietf-pana-threats-eval] for a detailed discussion. In environments where no secure channel prior to the PANA execution is available, PANA needs to protect itself against a number of attacks. The device identifier that is used during the authentication needs to be verified at the end of the authentication to prevent service theft and DoS attacks. Additionally, a free loader should be prevented from spoofing data packets by using the device identifier of an already authorized legitimate client. Both of these requirements necessitate generation of a security association between the PaC and the PAA at the end of the authentication. This can only be done when the authentication method used can generate session keys. Use of session keys can prevent attacks which would otherwise be very easy to launch by eavesdropping on and spoofing traffic over an insecure link. The EAP method provided session key is transported to the PAA (if necessary) and is subsequently input to the creation of the PANA SA. Applying the PANA SA to the messages exchanged during the final PANA handshake provides implicit key confirmation to both the PAA and the PaC. Implicit key confirmation shows both, the PaC and the PAA, that they possess the unique and fresh session key. Protecting the final PANA handshake also ensures that the device identifier (and other information) cannot be modified by an adversary. Further usage of the keying material is discussed in [I-D.ietf-pana-framework]. Forsberg, et al. Expires January 15, 2005 [Page 34] Internet-Draft PANA July 2004 6. Message Formats This section defines message formats for PANA protocol. 6.1 IP and UDP Headers The Hop Limit (or TTL) field of the IP header MUST be set to 255. When a PANA-PAA-Discover message is multicast, IP destination address of the message is set to a well-known link-local multicast address (TBD). A PANA-PAA-Discover message MAY be unicast in some cases as specified in Section 4.2. Any other PANA packet is unicasted between the PaC and the PAA. The source and destination addresses SHOULD be set to the addresses on the interfaces from which the message will be sent and received, respectively. When the PANA packet is sent in response to a request, the UDP source and destination ports of the response packet MUST be copied from the destination and source ports of the request packet, respectively. The destination port of an unsolicited PANA packet MUST be set to an assigned value (TBD), and the source port MUST be set to a value chosen by the sender. 6.2 PANA Header A summary of the PANA header format is shown below. The fields are transmitted in network byte order. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | Message Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Transmitted Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Received Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AVPs ... +-+-+-+-+-+-+-+-+-+-+-+-+- Version Forsberg, et al. Expires January 15, 2005 [Page 35] Internet-Draft PANA July 2004 This Version field MUST be set to 1 to indicate PANA Version 1. Message Length The Message Length field is three octets and indicates the length of the PANA message including the header fields. Flags The Flags field is eight bits. The following bits are assigned: 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |R r r r S N r r| +-+-+-+-+-+-+-+-+ R(equest) If set, the message is a request. If cleared, the message is an answer. S(eparate) When the S-flag is set in a PANA-Start-Request message it indicates that PAA is willing to offer separate EAP authentications for NAP and ISP. When the S-flag is set in a PANA-Start-Answer message it indicates that PaC accepts on performing separate EAP authentications for NAP and ISP. When the S-flag is set in a PANA-Auth-Request/Answer, PANA-FirstAuth-End-Request/Answer and PANA-Bind-Request/Answer messages it indicates that separate authentications are being performed in the authentication phase. N(AP authentication) When the N-flag is set in a PANA-Auth-Request message, it indicates that PAA is performing NAP authentication. When the N-flag is unset in a PANA-Auth-Request message, it indicates that PAA is performing ISP authentication. The N-flag MUST NOT be set when S-flag is not set. r(eserved) these flag bits are reserved for future use, and MUST be set to zero, and ignored by the receiver. Forsberg, et al. Expires January 15, 2005 [Page 36] Internet-Draft PANA July 2004 Message Type The Message Type field is three octets, and is used in order to communicate the message type with the message. The 24-bit address space is managed by IANA [ianaweb]. PANA uses its own address space for this field. Transmitted Sequence Number The Transmitted Sequence Number field contains the monotonically increasing 32 bit sequence number that the message sender increments every time a new PANA message is sent. Received Sequence Number The Received Sequence Number field contains the 32 bit transmitted sequence number that the message sender has last received from its peer. AVPs AVPs are a method of encapsulating information relevant to the PANA message. See section Section 6.3 for more information on AVPs. 6.3 AVP Header Each AVP of type OctetString MUST be padded to align on a 32-bit boundary, while other AVP types align naturally. A number of zero-valued bytes are added to the end of the AVP Data field till a word boundary is reached. The length of the padding is not reflected in the AVP Length field [RFC3588]. The fields in the AVP header MUST be sent in network byte order. The format of the header is: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AVP Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AVP Flags | AVP Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Vendor-Id (opt) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Data ... +-+-+-+-+-+-+-+-+ Forsberg, et al. Expires January 15, 2005 [Page 37] Internet-Draft PANA July 2004 AVP Code The AVP Code, combined with the Vendor-Id field, identifies the attribute uniquely. AVP numbers are allocated by IANA [ianaweb]. PANA uses its own address space for this field although some of the AVP formats are borrowed from Diameter protocol [RFC3588]. AVP Flags The AVP Flags field is eight bits. The following bits are assigned: 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |V M r r r r r r| +-+-+-+-+-+-+-+-+ M(andatory) The 'M' Bit, known as the Mandatory bit, indicates whether support of the AVP is required. V(endor) The 'V' bit, known as the Vendor-Specific bit, indicates whether the optional Vendor-Id field is present in the AVP header. r(eserved) these flag bits are reserved for future use, and MUST be set to zero, and ignored by the receiver. AVP Length The AVP Length field is three octets, and indicates the number of octets in this AVP including the AVP Code, AVP Length, AVP Flags, and the AVP data Vendor-Id The Vendor-Id field is present if the 'V' bit is set in the AVP Flags field. The optional four-octet Vendor-Id field contains the IANA assigned "SMI Network Management Private Enterprise Codes" [ianaweb] value, encoded in network byte order. Any vendor wishing to implement a vendor-specific PANA AVP MUST use their own Forsberg, et al. Expires January 15, 2005 [Page 38] Internet-Draft PANA July 2004 Vendor-Id along with their privately managed AVP address space, guaranteeing that they will not collide with any other vendor's vendor-specific AVP(s), nor with future IETF applications. Data The Data field is zero or more octets and contains information specific to the Attribute. The format and length of the Data field is determined by the AVP Code and AVP Length fields. 6.4 PANA Messages Figure 11 lists all PANA messages defined in this document Message Direction: PaC---PAA ---------------------------------------- PANA-PAA-Discover --------> PANA-Start-Request <-------- PANA-Start-Answer --------> PANA-Auth-Request <-------- PANA-Auth-Answer --------> PANA-FirstAuth-End-Request <-------- PANA-FirstAuth-End-Answer --------> PANA-Bind-Request <-------- PANA-Bind-Answer --------> PANA-Reauth-Request <-------> PANA-Reauth-Answer <-------> PANA-Termination-Request <-------> PANA-Termination-Answer <-------> PANA-Update-Request --------> PANA-Update-Answer <-------- PANA-Error <-------> Figure 11: PANA Message Overview 6.4.1 Message Specifications Every PANA message MUST include a corresponding ABNF [RFC2234] Forsberg, et al. Expires January 15, 2005 [Page 39] Internet-Draft PANA July 2004 specification found in [RFC3588]. Note that PANA messages have a different header format compared to Diameter. Example: message ::= < PANA-Header: , [REQ] [SEP] > * [ AVP ] 6.4.2 PANA-PAA-Discover (PDI) The PANA-PAA-Discover (PDI) message is used to discover the address of PAA(s). Both sequence numbers in this message are set to zero (0). PANA-PAA-Discover ::= < PANA-Header: 1 > 0*1 < Session-Id > * [ AVP ] 6.4.3 PANA-Start-Request (PSR) PANA-Start-Request (PSR) is sent by the PAA to the PaC. The PAA sets the transmission sequence number to an initial random value. The received sequence number is set to zero (0). PANA-Start-Request ::= < PANA-Header: 2, REQ [SEP] > { Nonce } [ Cookie ] [ EAP-Payload ] [ NAP-Information ] * [ ISP-Information ] [ Protection-Capability] [ PPAC ] * [ AVP ] 6.4.4 PANA-Start-Answer (PSA) PANA-Start-Answer (PSA) is sent by the PaC to the PAA in response to a PANA-Start-Request message. The PANA_start message transmission sequence number field is copied to the received sequence number field. The transmission sequence number is set to initial random value. PANA-Start-Answer ::= < PANA-Header: 2 [SEP] > { Nonce } [ Session-Id ] Forsberg, et al. Expires January 15, 2005 [Page 40] Internet-Draft PANA July 2004 [ Cookie ] [ EAP-Payload ] [ ISP-Information ] * [ AVP ] 0*1 < MAC > 6.4.5 PANA-Auth-Request (PAR) PANA-Auth-Request (PAR) is sent by the PAA to the PaC. PANA-Auth-Request ::= < PANA-Header: 3, REQ [SEP] [NAP] > < Session-Id > < EAP-Payload > * [ AVP ] 0*1 < MAC > (Both NAP-Information and ISP-Information MUST NOT be included at the same time) 6.4.6 PANA-Auth-Answer (PAN) PANA-Auth-Answer (PAN) is sent by the PaC to the PAA in response to a PANA-Auth-Request message. PANA-Auth-Answer ::= < PANA-Header: 3 [SEP] [NAP] > < Session-Id > < EAP-Payload > * [ AVP ] 0*1 < MAC > 6.4.7 PANA-Bind-Request (PBR) PANA-Bind-Request (PBR) is sent by the PAA to the PaC. PANA-Bind-Request ::= < PANA-Header: 4, REQ [SEP] [NAP] > < Session-Id > { Result-Code } { PPAC } [ EAP-Payload ] [ Device-Id ] [ Session-Lifetime ] [ Protection-Capability ] [ Key-Id ] * [ EP-Device-Id ] * [ AVP ] 0*1 < MAC > Forsberg, et al. Expires January 15, 2005 [Page 41] Internet-Draft PANA July 2004 6.4.8 PANA-Bind-Answer (PBA) PANA-Bind-Answer (PBA) is sent by the PaC to the PAA in response to a PANA-Result-Request message. PANA-Bind-Answer ::= < PANA-Header: 4 [,SEP] [NAP] > < Session-Id > { Result-Code } [ PPAC ] [ Device-Id ] [ Key-Id ] * [ AVP ] 0*1 < MAC > 6.4.9 PANA-Reauth-Request (PRAR) PANA-Reauth-Request (PRAR) is either sent by the PaC or the PAA. PANA-Reauth-Request ::= < PANA-Header: 5, REQ > < Session-Id > * [ AVP ] 0*1 < MAC > 6.4.10 PANA-Reauth-Answer (PRAA) PANA-Reauth-Answer (PRAA) is sent in response to a PANA-Reauth-Request. PANA-Reauth-Answer ::= < PANA-Header: 5 > < Session-Id > * [ AVP ] 0*1 < MAC > 6.4.11 PANA-Termination-Request (PTR) PANA-Termination-Request (PTR) is sent either by the PaC or the PAA. PANA-Termination-Request ::= < PANA-Header: 6, REQ > < Session-Id > < Termination-Cause > * [ AVP ] 0*1 < MAC > Forsberg, et al. Expires January 15, 2005 [Page 42] Internet-Draft PANA July 2004 6.4.12 PANA-Termination-Answer (PTA) PANA-Termination-Answer (PTA) is sent either by the PaC or the PAA in response to PANA-Termination-Request. PANA-Termination-Answer ::= < PANA-Header: 6 > < Session-Id > * [ AVP ] 0*1 < MAC > 6.4.13 PANA-Error (PER) PANA-Error is sent either by the PaC or the PAA. PANA-Error ::= < PANA-Header: 7 > < Session-Id > < Result-Code > { Failed-AVP } * [ AVP ] 0*1 < MAC > 6.4.14 PANA-FirstAuth-End-Request (PFER) PANA-FirstAuth-End-Request (PFER) is sent by the PAA to the PaC. PANA-FirstAuth-End-Request ::= < PANA-Header: 8, REQ [SEP] [NAP] > < Session-Id > < Device-Id > { EAP-Payload } { Result-Code } [ Key-Id ] * [ AVP ] 0*1 < MAC > 6.4.15 PANA-FirstAuth-End-Answer (PFEA) PANA-FirstAuth-End-Answer (PFEA) is sent by the PaC to the PAA in response to a PANA-FirstAuth-End-Request message. PANA-FirstAuth-End-Answer ::= < PANA-Header: 8, REQ [SEP] [NAP] > < Session-Id > < Device-Id > [ Key-Id ] * [ AVP ] 0*1 < MAC > Forsberg, et al. Expires January 15, 2005 [Page 43] Internet-Draft PANA July 2004 6.4.16 PANA-Update-Request (PUR) PANA-Update-Request (PUR) is sent by the PaC to the PAA. PANA-Update-Request ::= < PANA-Header: 9, REQ > < Session-Id > < IP-Address > * [ AVP ] 0*1 < MAC > 6.4.17 PANA-Update-Answer (PUA) PANA-Update-Answer (PUA) is sent by the PAA to the PaC in response to a PANA-Update-Request. PANA-Update-Answer ::= < PANA-Header: 9 > < Session-Id > * [ AVP ] 0*1 < MAC > 6.5 AVPs in PANA Some of the used AVPs are defined in this document and some of them are defined in other documents like [RFC3588]. PANA proposes to use the same name space with [RFC3588]. For temporary allocation, PANA uses AVP type numbers starting from 1024. 6.5.1 MAC AVP The first octet (8 bits) of the MAC (Code 1024) AVP data contains the MAC algorithm type. Rest of the AVP data payload contains the MAC encoded in network byte order. The Algorithm 8 bit name space is managed by IANA [ianaweb]. The AVP length varies depending on the used algorithm. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Algorithm | MAC... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Algorithm 1 HMAC-SHA1 (20 bytes) Forsberg, et al. Expires January 15, 2005 [Page 44] Internet-Draft PANA July 2004 MAC The Message Authentication Code is encoded in network byte order. 6.5.2 Device-Id AVP The Device-Id AVP (Code 1025) is of Address type [RFC3588]. IPv4 and IPv6 addresses are encoded as specified in [RFC3588]. The content and format of data (including byte and bit ordering) for link-layer addresses is expected to be specified in specific documents that describe how IP operates over different link-layers. For instance, [RFC2464]. Address families other than that are defined for link-layer or IP addresses MUST NOT be used for this AVP. 6.5.3 Session-Id AVP All messages pertaining to a specific PANA session MUST include a Session-Id AVP (Code 1026) which carries a PAA-assigned fix value throughout the lifetime of a session. When present, the Session-Id SHOULD appear immediately following the PANA header. The Session-Id MUST be globally and eternally unique, as it is meant to identify a PANA Session without reference to any other information, and may be needed to correlate historical authentication information with accounting information. The PANA Session-Id AVP has the same format as the Diameter Session-Id AVP [RFC3588]. 6.5.4 Cookie AVP The Cookie AVP (Code 1027) is of type OctetString. The data is opaque and the exact content is outside the scope of this protocol. 6.5.5 Protection-Capability AVP The Protection-Capability AVP (Code 1028) is of type Unsigned32. The AVP data indicates the cryptographic data protection capability supported by the EPs. Below is a list of specified data protection capabilities: 0 L2_PROTECTION 1 IPSEC_PROTECTION 6.5.6 Termination-Cause AVP The Termination-Cause AVP (Code 1029) is of type of type Enumerated, and is used to indicate the reason why a session was terminated on the access device. The AVP data is used as a collection of flags The following Termination-Cause AVP defined in [RFC3588] are used for Forsberg, et al. Expires January 15, 2005 [Page 45] Internet-Draft PANA July 2004 PANA. LOGOUT 1 (PaC -> PAA) The client initiated a disconnect ADMINISTRATIVE 4 (PAA -> Pac) The client was not granted access, or was disconnected, due to administrative reasons, such as the receipt of a Abort-Session-Request message. SESSION_TIMEOUT 8 (PAA -> PaC) The session has timed out, and service has been terminated. 6.5.7 Result-Code AVP The Result-Code AVP (AVP Code 1030) is of type Unsigned32 and indicates whether an EAP authentication was completed successfully or whether an error occurred. Here are Result-Code AVP values taken from [RFC3588] and adapted for PANA. 6.5.7.1 Authentication Results Codes These result code values inform the PaC about the authentication and authorization result. The authentication result and authorization result can be different as described below, but only one result that corresponds to the one detected first is returned. PANA_SUCCESS 2001 Both the authentication and authorization processes are successful. PANA_AUTHENTICATION_REJECTED 4001 The authentication process failed. When this error is returned, the authorization process also fails. PANA_AUTHORIZATION_REJECTED 5003 The authorization process failed. This error could occur when authorization is rejected by a AAA proxy or rejected locally by a PAA, even if the authentication procedure succeeds. Forsberg, et al. Expires January 15, 2005 [Page 46] Internet-Draft PANA July 2004 6.5.7.2 Protocol Error Result Codes Protocol error result code values. PANA_MESSAGE_UNSUPPORTED 3001 Error code from PAA to PaC or from PaC to PAA. Message type not recognized or supported. PANA_UNABLE_TO_DELIVER 3002 Error code from PAA to PaC. PAA was unable to deliver the EAP payload to the authentication server. PANA_INVALID_HDR_BITS 3008 Error code from PAA to PaC or from PaC to PAA. A message was received whose bits in the PANA header were either set to an invalid combination, or to a value that is inconsistent with the message type's definition. PANA_INVALID_AVP_BITS 3009 Error code from PAA to PaC or from PaC to PAA. A message was received that included an AVP whose flag bits are set to an unrecognized value, or that is inconsistent with the AVP's definition. PANA_AVP_UNSUPPORTED 5001 Error code from PAA to PaC or from PaC to PAA. The received message contained an AVP that is not recognized or supported and was marked with the Mandatory bit. A PANA message with this error MUST contain one or more Failed-AVP AVP containing the AVPs that caused the failure. PANA_UNKNOWN_SESSION_ID 5002 Error code from PAA to PaC or from PaC to PAA. The message contained an unknown Session-Id. PAA MUST NOT send this error result code value to PaC if PaC sent an unknown Session-Id in the PANA-Start-Answer message (session resumption). PANA_INVALID_AVP_VALUE 5004 Forsberg, et al. Expires January 15, 2005 [Page 47] Internet-Draft PANA July 2004 Error code from PAA to PaC or from PaC to PAA. The message contained an AVP with an invalid value in its data portion. A PANA message indicating this error MUST include the offending AVPs within a Failed-AVP AVP. PANA_MISSING_AVP 5005 Error code from PAA to PaC or from PaC to PAA. The message did not contain an AVP that is required by the message type definition. If this value is sent in the Result-Code AVP, a Failed-AVP AVP SHOULD be included in the message. The Failed-AVP AVP MUST contain an example of the missing AVP complete with the Vendor-Id if applicable. The value field of the missing AVP should be of correct minimum length and contain zeroes. PANA_RESOURCES_EXCEEDED 5006 Error code from PAA to PaC. A message was received that cannot be authorized because the client has already expended allowed resources. An example of this error condition is a client that is restricted to one PANA session and attempts to establish a second session. PANA_CONTRADICTING_AVPS 5007 Error code from PAA to PaC. The PAA has detected AVPs in the message that contradicted each other, and is not willing to provide service to the client. One or more Failed-AVP AVPs MUST be present, containing the AVPs that contradicted each other. PANA_AVP_NOT_ALLOWED 5008 Error code from PAA to PaC or from PaC to PAA. A message was received with an AVP that MUST NOT be present. The Failed-AVP AVP MUST be included and contain a copy of the offending AVP. PANA_AVP_OCCURS_TOO_MANY_TIMES 5009 Error code from PAA to PaC or from PaC to PAA. A message was received that included an AVP that appeared more often than permitted in the message definition. The Failed-AVP AVP MUST be included and contain a copy of the first instance of the offending AVP that exceeded the maximum number of occurrences. PANA_UNSUPPORTED_VERSION 5011 Forsberg, et al. Expires January 15, 2005 [Page 48] Internet-Draft PANA July 2004 Error code from PAA to PaC or from PaC to PAA. This error is returned when a message was received, whose version number is unsupported. PANA_UNABLE_TO_COMPLY 5012 This error is returned when a request is rejected for unspecified reasons. For example, when an EAP authentication fails at an EAP pass-through authenticator without passing an EAP-Failure message to the PAA, a Result-Code AVP with this error code is carried in PANA-Error message. PANA_INVALID_AVP_LENGTH 5014 Error code from PAA to PaC or from PaC to PAA. The message contained an AVP with an invalid length. The PANA-Error message indicating this error MUST include the offending AVPs within a Failed-AVP AVP. PANA_INVALID_MESSAGE_LENGTH 5015 Error code from PAA to PaC or from PaC to PAA. This error is returned when a message is received with an invalid message length. PANA_PROTECTION_CAPABILITY_UNSUPPORTED 5016 Error code from PaC to PAA. This error is returned when the PaC receives a PANA-Bind-Request is received with an Protection-Capability AVP and a valid MAC AVP but does not support the protection capability specified in the Protection-Capability AVP. PANA_PPAC_CAPABILITY_UNSUPPORTED 5017 Error code from PaC to PAA. This error is returned in a PANA-Bind-Answer message when there is no match between the list of PPAC methods offered by the PAA and the ones available on the PaC. PANA_INVALID_IP_ADDRESS 5018 Error code from PAA to PaC. This error is returned in a PANA-Error message when the IP-Address AVP in the received PANA-Update-Request message is invalid (e.g., a non-unicast address). Forsberg, et al. Expires January 15, 2005 [Page 49] Internet-Draft PANA July 2004 6.5.8 EAP-Payload AVP The EAP-Payload AVP (AVP Code 1031) is of type OctetString and is used to encapsulate the actual EAP packet that is being exchanged between the EAP peer and the EAP authenticator. 6.5.9 Session-Lifetime AVP The Session-Lifetime AVP (Code 1032) data is of type Unsigned32. It contains the number of seconds remaining before the current session is considered expired. 6.5.10 Failed-AVP AVP The Failed-AVP AVP (AVP Code 1033) is of type Grouped and provides debugging information in cases where a request is rejected or not fully processed due to erroneous information in a specific AVP. The format of the Failed-AVP AVP is defined in [RFC3588]. 6.5.11 NAP-Information AVP The NAP-Information AVP (AVP Code: 1034) is of type Grouped, and contains zero or one Provider-Identifier AVP which carries the identifier of the NAP and one Provider-Name AVP which carries the name of the NAP. Its Data field has the following ABNF grammar: NAP-Information ::= < AVP Header: 1034 > 0*1 { Provider-Identifier } { Provider-Name } * [ AVP ] 6.5.12 ISP-Information AVP The ISP-Information AVP (AVP Code: 1035) is of type Grouped, and contains zero or one Provider-Identifier AVP which carries the identifier of the ISP and one Provider-Name AVP which carries the name of the ISP. Its Data field has the following ABNF grammar: ISP-Information ::= < AVP Header: 1035 > 0*1 { Provider-Identifier } { Provider-Name } * [ AVP ] 6.5.13 Provider-Identifier AVP The Provider-Identifier AVP (AVP Code: 1036) is of type Unsigned32, Forsberg, et al. Expires January 15, 2005 [Page 50] Internet-Draft PANA July 2004 and contains an IANA assigned "SMI Network Management Private Enterprise Codes" [ianaweb] value, encoded in network byte order. 6.5.14 Provider-Name AVP The Provider-Name AVP (AVP Code: 1037) is of type UTF8String, and contains the UTF8-encoded name of the provider. 6.5.15 EP-Device-Id AVP The EP-Device-Id AVP (AVP Code: 1038) contains the device identifier of an EP. The payload format of the EP-Device-Id AVP is the same as that of the Device-Id AVP (see See section Section 6.5.2). 6.5.16 Key-Id AVP The Key-Id AVP (AVP Code: 1039) is of type Integer32, and contains an AAA-Key identifier. The AAA-Key identifier is assigned by PAA and MUST be unique within the PANA session. 6.5.17 Post-PANA-Address-Configuration (PPAC) AVP The data field of PPAC AVP (Code 1040) is of type Unsigned32. The AVP data is used to carry a set of flags which maps to various IP address configuration methods. When sent by the PAA, the AVP MUST have at least one of the flags set, and MAY have more than one set. When sent by the PaC, only one of the flags MUST be set. The format of the AVP data is 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |N|D|A|T|I| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ PPAC Flags N (No configuration) The PaC does not have to (if sent by PAA) or will not (if sent by PaC) configure a new IP address after PANA. D (DHCP) Forsberg, et al. Expires January 15, 2005 [Page 51] Internet-Draft PANA July 2004 The PaC can (if sent by PAA) or will (if sent by PaC) use DHCP [RFC2131][RFC3315] to configure a new IP address after PANA. A (stateless autoconfiguration) The PaC can/will use stateless IPv6 address autoconfiguration [RFC2462] to configure a new IP address after PANA. T (DHCP with IPsec tunnel mode) The PaC can/will use [RFC3456] to configure a new IP address after PANA. I (IKEv2) The PaC can/will use [I-D.ietf-ipsec-ikev2] to configure a new IP address after PANA. Reserved These flag bits are reserved for future use, and MUST be set to zero, and ignored by the receiver. Unless the N-flag is set, the PaC MUST configure a new IP address using one of the methods indicated by the other flags. Refer to [I-D.ietf-pana-framework] for a detailed discussion on when these methods can be used. 6.5.18 Nonce AVP The Nonce AVP (Code 1041) is of type OctetString. The data contains a randomly generated value in opaque format. The data length MUST be between 8 and 256 bytes inclusive. 6.5.19 IP-Address AVP The IP-Address (AVP Code: 1042) contains an IP address of a PaC. The payload format of the IP-Address AVP is the same as that of the Device-Id AVP (see See section Section 6.5.2). Address families for IPv4 or IPv6 MUST be used for this AVP. 6.6 AVP Occurrence Table The following tables lists the AVPs used in this document, and specifies in which PANA messages they MAY, or MAY NOT be present. The table uses the following symbols: Forsberg, et al. Expires January 15, 2005 [Page 52] Internet-Draft PANA July 2004 0 The AVP MUST NOT be present in the message. 0+ Zero or more instances of the AVP MAY be present in the message. 0-1 Zero or one instance of the AVP MAY be present in the message. It is considered an error if there are more than one instance of the AVP. 1 One instance of the AVP MUST be present in the message. 1+ At least one instance of the AVP MUST be present in the message. +-----------------------------------------+ | Message | | Type | +-----+-----+-----+-----+-----+-----+-----+ Attribute Name | PSR | PSA | PAR | PAN | PBR | PBA | PDI | --------------------+-----+-----+-----+-----+-----+-----+-----+ Result-Code | 0 | 0 | 0 | 0 | 1 | 1 | 0 | Session-Id | 0 | 0-1 | 1 | 1 | 1 | 1 | 0-1 | Termination-Cause | 0 | 0 | 0 | 0 | 0 | 0 | 0 | EAP-Payload | 0-1 | 0-1 | 1 | 1 | 0-1 | 0 | 0 | MAC | 0 | 0-1 | 0-1 | 0-1 | 0-1 | 0-1 | 0 | Nonce | 1 | 1 | 0 | 0 | 0 | 0 | 0 | Device-Id | 0 | 0 | 0 | 0 | 0-1 | 0-1 | 0 | Cookie | 0-1 | 0-1 | 0 | 0 | 0 | 0 | 0 | Protection-Cap. | 0-1 | 0 | 0 | 0 | 0-1 | 0 | 0 | PPAC | 0-1 | 0 | 0 | 0 | 1 | 0-1 | 0 | Session-Lifetime | 0 | 0 | 0 | 0 | 0-1 | 0 | 0 | Failed-AVP | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ISP-Information | 0+ | 0-1 | 0 | 0 | 0 | 0 | 0 | NAP-Information | 0-1 | 0 | 0 | 0 | 0 | 0 | 0 | EP-Device-Id | 0 | 0 | 0 | 0 | 0+ | 0 | 0 | Key-Id | 0 | 0 | 0 | 0 | 0-1 | 0-1 | 0 | IP-Address | 0 | 0 | 0 | 0 | 0 | 0 | 0 | --------------------+-----+-----+-----+-----+-----+-----+-----+ Figure 12: AVP Occurrence Table (1/3) Forsberg, et al. Expires January 15, 2005 [Page 53] Internet-Draft PANA July 2004 +---------------------------------------------+ | Message | | Type | +------+------+-----+-----+-----+------+------+ Attribute Name | PRAR | PRAA | PTR | PTA | PER | PFER | PFEA | --------------------+------+------+-----+-----+-----+------+------+ Result-Code | 0 | 0 | 0 | 0 | 1 | 1 | 0 | Session-Id | 1 | 1 | 1 | 1 | 1 | 1 | 1 | Termination-Cause | 0 | 0 | 1 | 0 | 0 | 0 | 0 | EAP-Payload | 0 | 0 | 0 | 0 | 0 | 1 | 0 | MAC | 0-1 | 0-1 | 0-1 | 0-1 | 0-1 | 0-1 | 0-1 | Nonce | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Device-Id | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Cookie | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Protection-Cap. | 0 | 0 | 0 | 0 | 0 | 0 | 0 | PPAC | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Session-Lifetime | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Failed-AVP | 0 | 0 | 0 | 0 | 1 | 0 | 0 | ISP-Information | 0 | 0 | 0 | 0 | 0 | 0 | 0 | NAP-Information | 0 | 0 | 0 | 0 | 0 | 0 | 0 | EP-Device-Id | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Key-Id | 0 | 0 | 0 | 0 | 0 | 0-1 | 0-1 | IP-Address | 0 | 0 | 0 | 0 | 0 | 0 | 0 | --------------------+------+------+-----+-----+-----+------+------+ Figure 13: AVP Occurrence Table (2/3) Forsberg, et al. Expires January 15, 2005 [Page 54] Internet-Draft PANA July 2004 +-----------+ | Message | | Type | +-----+-----+ Attribute Name | PUR | PUA | --------------------+-----+-----+ Result-Code | 0 | 0 | Session-Id | 1 | 1 | Termination-Cause | 0 | 0 | EAP-Payload | 0 | 0 | MAC | 0-1 | 0-1 | Nonce | 0 | 0 | Device-Id | 0 | 0 | Cookie | 0 | 0 | Protection-Cap. | 0 | 0 | PPAC | 0 | 0 | Session-Lifetime | 0 | 0 | Failed-AVP | 0 | 0 | ISP-Information | 0 | 0 | NAP-Information | 0 | 0 | EP-Device-Id | 0 | 0 | Key-Id | 0 | 0 | IP-Address | 1 | 0 | --------------------+-----+-----+ Figure 14: AVP Occurrence Table (3/3) Forsberg, et al. Expires January 15, 2005 [Page 55] Internet-Draft PANA July 2004 7. PANA Protocol Message Retransmissions The PANA protocol provides retransmissions for all the message exchanges except PANA-Auth-Request/Answer. PANA-Auth-Request messages carry EAP requests which are retransmitted by the EAP protocol entities when needed. The messages that need PANA-level retransmissions are listed below: PANA-PAA-Discover (PDI) PANA-Start-Request (PSR)* PANA-Start-Answer (PSA)** PANA-Bind-Request (PBR) PANA-FirstAuth-End-Request (PFER) PANA-Reauth-Request (PRAR) PANA-Termination-Request (PTR) PANA-Update-Request (PUR) *) PSR that carries a Cookie AVP is not retransmitted. **) PSA that does not carry a Cookie AVP is not retransmitted. The PDI and PSA messages are always sent by the PaC. PBR is sent by PAA. The last two messages, PRAR and PTR are sent either by PaC or PAA. The rule is that the sender of the request message retransmits the request if the corresponding answer is not received in time. Answer messages are sent as answers to the request messages, not based on a timer. Exception to this rule is the PSA message. Because of the stateless nature of the PAA in the beginning PaC provides retransmission also for the PSA message. PANA-Error messages MUST NOT be retransmitted. See Section 4.1.8 for more details of PANA error handling. PANA retransmission timers are based on the model used in DHCPv6 [RFC3315]. Variables used here are also borrowed from this specification. PANA is a request response like protocol. The message exchange terminates when either the request sender successfully receives the appropriate answer, or when the message exchange is considered to have failed according to the retransmission mechanism described below. The retransmission behavior is controlled and described by the following variables: RT Retransmission timeout IRT Initial retransmission time Forsberg, et al. Expires January 15, 2005 [Page 56] Internet-Draft PANA July 2004 MRC Maximum retransmission count MRT Maximum retransmission time MRD Maximum retransmission duration RAND Randomization factor With each message transmission or retransmission, the sender sets RT according to the rules given below. If RT expires before the message exchange terminates, the sender recomputes RT and retransmits the message. Each of the computations of a new RT include a randomization factor (RAND), which is a random number chosen with a uniform distribution between -0.1 and +0.1. The randomization factor is included to minimize synchronization of messages. The algorithm for choosing a random number does not need to be cryptographically sound. The algorithm SHOULD produce a different sequence of random numbers from each invocation. RT for the first message transmission is based on IRT: RT = IRT + RAND*IRT RT for each subsequent message transmission is based on the previous value of RT: RT = 2*RTprev + RAND*RTprev MRT specifies an upper bound on the value of RT (disregarding the randomization added by the use of RAND). If MRT has a value of 0, there is no upper limit on the value of RT. Otherwise: if (RT > MRT) RT = MRT + RAND*MRT MRC specifies an upper bound on the number of times a sender may retransmit a message. Unless MRC is zero, the message exchange fails once the sender has transmitted the message MRC times. MRD specifies an upper bound on the length of time a sender may retransmit a message. Unless MRD is zero, the message exchange fails once MRD seconds have elapsed since the client first transmitted the message. If both MRC and MRD are non-zero, the message exchange fails whenever Forsberg, et al. Expires January 15, 2005 [Page 57] Internet-Draft PANA July 2004 either of the conditions specified in the previous two paragraphs are met. If both MRC and MRD are zero, the client continues to transmit the message until it receives a response. 7.1 Transmission and Retransmission Parameters This section presents a table of values used to describe the message retransmission behavior of request and PANA-Start-Answer messages marked with REQ_*. PANA-PAA-Discover message retransmission values are marked with PDI_*. The table shows default values. Parameter Default Description ------------------------------------------------ PDI_IRT 1 sec Initial PDI timeout. PDI_MRT 120 secs Max PDI timeout value. PDI_MRC 0 Configurable. PDI_MRD 0 Configurable. REQ_IRT 1 sec Initial Request timeout. REQ_MRT 30 secs Max Request timeout value. REQ_MRC 10 Max Request retry attempts. REQ_MRD 0 Configurable. So for example the first RT for the PBR message is calculated using REQ_IRT as the IRT: RT = REQ_IRT + RAND*REQ_IRT Forsberg, et al. Expires January 15, 2005 [Page 58] Internet-Draft PANA July 2004 8. IANA Considerations This section provides guidance to the Internet Assigned Numbers Authority (IANA) regarding registration of values related to the PANA protocol, in accordance with BCP 26 [IANA]. The following policies are used here with the meanings defined in BCP 26: "Private Use", "First Come First Served", "Expert Review", "Specification Required", "IETF Consensus", "Standards Action". This section explains the criteria to be used by the IANA for assignment of numbers within namespaces defined within this document. For registration requests where a Designated Expert should be consulted, the responsible IESG area director should appoint the Designated Expert. For Designated Expert with Specification Required, the request is posted to the PANA WG mailing list (or, if it has been disbanded, a successor designated by the Area Director) for comment and review, and MUST include a pointer to a public specification. Before a period of 30 days has passed, the Designated Expert will either approve or deny the registration request and publish a notice of the decision to the PANA WG mailing list or its successor. A denial notice must be justified by an explanation and, in the cases where it is possible, concrete suggestions on how the request can be modified so as to become acceptable. 8.1 PANA UDP Port Number PANA uses one well-known UDP port number (Section 4.1.2, Section 4.2 and Section 6.1, which needs to be assigned by the IANA. 8.2 PANA Multicast Address PANA uses one well-known IPv4 multicast address for which the scope is limited to be link-local by setting the TTL field to 255, and one well-known IPv6 link-local scoped multicast address (Section 4.2 and Section 6.1), which need to be assigned by the IANA. 8.3 PANA Header As defined in Section 6.2, the PANA header contains two fields that requires IANA namespace management; the Message Type and Flags field. 8.3.1 Message Type The Message Type namespace is used to identify PANA messages. Values 0-16,777,213 are for permanent, standard message types, allocated by IETF Consensus [IANA]. This document defines the Message Types 1-8. See Section 6.4.1 for the assignment of the namespace in this Forsberg, et al. Expires January 15, 2005 [Page 59] Internet-Draft PANA July 2004 specification. The values 16,777,214 and 16,777,215 (hexadecimal values 0xfffffe - 0xffffff) are reserved for experimental messages. As these codes are only for experimental and testing purposes, no guarantee is made for interoperability between communicating PaC and PAA using experimental commands, as outlined in [IANA-EXP]. 8.3.2 Flags There are eight bits in the Flags field of the PANA header. This document assigns bit 0 ('R'equest), bit 4 ('S'eparate) and bit 5 ('N'AP Authentication). The remaining bits MUST only be assigned via a Standards Action [IANA]. 8.4 AVP Header As defined in Section 6.3, the AVP header contains three fields that requires IANA namespace management; the AVP Code, AVP Flags and Vendor-Id fields where only the AVP Code and AVP Flags create new namespaces. 8.4.1 AVP Code The AVP Code namespace is used to identify attributes. There are multiple namespaces. Vendors can have their own AVP Codes namespace which will be identified by their Vendor-ID (also known as Enterprise-Number) and they control the assignments of their vendor-specific AVP codes within their own namespace. The absence of a Vendor-ID or a Vendor-ID value of zero (0) identifies the IETF IANA controlled AVP Codes namespace. The AVP Codes and sometimes also possible values in an AVP are controlled and maintained by IANA. AVP Code 0 is not used. This document defines the AVP Codes 1024-1041. See Section 6.5 for the assignment of the namespace in this specification. AVPs may be allocated following Designated Expert with Specification Required [IANA]. Release of blocks of AVPs (more than 3 at a time for a given purpose) should require IETF Consensus. Note that PANA defines a mechanism for Vendor-Specific AVPs, where the Vendor-Id field in the AVP header is set to a non-zero value. Vendor-Specific AVPs codes are for Private Use and should be encouraged instead of allocation of global attribute types, for functions specific only to one vendor's implementation of PANA, where no interoperability is deemed useful. Where a Vendor-Specific AVP is implemented by more than one vendor, allocation of global AVPs should Forsberg, et al. Expires January 15, 2005 [Page 60] Internet-Draft PANA July 2004 be encouraged instead. 8.4.2 Flags There are 8 bits in the AVP Flags field of the AVP header, defined in Section 6.3. This document assigns bit 0 ('V'endor Specific) and bit 1 ('M'andatory). The remaining bits should only be assigned via a Standards Action . 8.5 AVP Values Certain AVPs in PANA define a list of values with various meanings. For attributes other than those specified in this section, adding additional values to the list can be done on a First Come, First Served basis by IANA [IANA]. 8.5.1 Algorithm Values of MAC AVP As defined in Section 6.5.1, the Algorithm field of MAC AVP (AVP Code 1024) defines the value of 1 (one) for HMAC-SHA1. All remaining values are available for assignment via IETF Consensus [IANA]. 8.5.2 Protection-Capability AVP Values As defined in Section 6.5.5, the Protection-Capability AVP (AVP Code 1028) defines the values 0 and 1. All remaining values are available for assignment via a Standards Action [IANA]. 8.5.3 Termination-Cause AVP Values As defined in Section 6.5.6, the Termination-Cause AVP (AVP Code 1029) defines the values 1, 4 and 8. All remaining values are available for assignment via IETF Consensus [IANA]. 8.5.4 Result-Code AVP Values As defined in Section 6.5.7, the Result-Code AVP (AVP Code 1030) defines the values 2001, 3001-3002, 3008-3009, 4001, 5001-5009 and 5011-5019. All remaining values are available for assignment via IETF Consensus [IANA]. Forsberg, et al. Expires January 15, 2005 [Page 61] Internet-Draft PANA July 2004 8.5.5 Post-PANA-Address-Configuration AVP Values As defined in Section 6.5.17, the Post-PANA-Address-Configuration AVP (AVP Code 1040) defines the bits 0 ('N': no configuration), 1 ('D': DHCP), 2 ('A' stateless autoconfiguration), 3 ('T': DHCP with IPsec tunnel mode) and 4 ('I': IKEv2). All remaining values are available for assignment via a Standards Action [IANA]. Forsberg, et al. Expires January 15, 2005 [Page 62] Internet-Draft PANA July 2004 9. Security Considerations The PANA protocol provides ordered delivery for EAP messages. If an EAP method that provides session keys is used, a PANA SA is created. The EAP Success/Failure message is one of the signaling messages which is integrity protected with this PANA SA. The PANA protocol does not provide security protection for the initial EAP message exchange. Integrity protection can only be provided after the PANA SA has been established. Thus, PANA re-authentication, revocation and disconnect notifications can be authenticated, integrity and replay protected. In certain environments (e.g., on a shared link) the EAP method selection is an important issue. The PANA framework described in this document covers the discussion of different protocols which are of interest for a protocol between the PaC and the PAA (typically referred as the PANA protocol). The PANA itself consists of a sequence of steps which are executed to complete the network access authentication procedure. Some of these steps are optional. The following execution steps have been identified as being relevant for PANA. They security considerations will be discussed in detail subsequently. a) Discovery message exchange In general it is difficult to prevent a vulnerabilities of the discovery protocol since the initial discovery are unsecured. To prevent very basic attacks an adversary should not be able to cause state creation with discovery messages at the PAA. This is prevented by re-using a cookie concept (see [RFC2522] which allows the responder to be stateless in the first message exchange. Because of the architectural assumptions made in PANA (i.e., the PAA is the on the same link as the PaC) the return-routability concept does not provide additional protection. Hence it is difficult to prevent this threat entirely. Furthermore it is not possible to shift heavy cryptographic operations to the PaC at the first few messages since the computational effort depends on the EAP method. The usage of client-puzzles as introduced by [jb99] is under investigation. Resistance against blind DoS attacks (i.e., attacks by off-path adversaries) is achieved with sequence numbers and cookies. Since PAA and PaC are supposed to be one IP hop away, a simple TTL check can prevent off-link attacks. Furthermore, additional filtering can be enabled on the EPs. An EP may be able to filter unauthorized PAA advertisements when they are received on the access Forsberg, et al. Expires January 15, 2005 [Page 63] Internet-Draft PANA July 2004 side of the network where only PaCs are connected. In networks where lower-layers are not secured prior to running PANA, the capability discovery enabled through inclusion of Protection-Capability and Post-PANA-Address-Configuration AVPs in PANA-Start-Request message is susceptible to spoofing. Therefore, usage of these AVPs during the discovery phase in such insecure networks is NOT RECOMMENDED. The same AVPs are delivered via an integrity-protected PANA-Bind-Request upon successful authentication. b) EAP over PANA message exchange The EAP derived session key is used to create a PANA security association. Since the execution of an EAP method might require a large number of roundtrips and no other session key is available it is not possible to secure the EAP message exchange itself. Hence an adversary can both eavesdrop the EAP messages and is also able to inject arbitrary messages which might confuse both the EAP peer on PaC and the EAP authenticator or authentication server on the PAA. The threats caused by this ability heavily depend on the EAP state machine. Since especially the PAA is not allowed to discard packets and packets have to be stored or forwarded to an AAA infrastructure some risk of DoS attacks exists. Eavesdropping EAP packets might cause problems when (a) the EAP method is weak and enables dictionary or replay attacks or even allows an adversary to learn the long-term password directly. Furthermore, if the optional EAP Identity payload is used then it allows the adversary to learn the identity of the PaC. In such a case a privacy problem is prevalent. To prevent these threats, [I-D.ietf-pana-framework] suggests using proper EAP methods for particular environments. Depending on the usage environment an EAP authentication has to be used for example which supports user identity confidentiality, protection against dictionary attacks and session key establishment. It is therefore the responsibility of the network operators and end users to choose the proper EAP method. PANA does not protect the EAP method exchange, but provides ordered delivery with sequence numbers. Sequence numbers and cookies provide resistance against blind DoS attacks. c) PANA SA establishment Once the EAP message authentication is finished a fresh and unique session key is available to the PaC and the PAA. This assumes that the EAP method allows session key derivation and that the generated Forsberg, et al. Expires January 15, 2005 [Page 64] Internet-Draft PANA July 2004 session key has a good quality. For further discussion about the importance of the session key generation refer to the next subsection (d) about compound authentication. The session key available for the PaC is established as part of the authentication and key exchange procedure of the selected EAP method. The PAA obtains the session key via the AAA infrastructure (if used). Security issues raised with this session key transport are described in [I-D.ietf-eap-keying]. The establishment of a PANA SA is required in environments where no physical or link layer security is available. The PANA SA allows subsequently exchanged messages to experience cryptographic protection. For the current version of the document an integrity object (MAC AVP) is defined which supports data-origin authentication, replay protection based on sequence numbers and integrity protection based on a keyed message digest. Confidentiality protection is not provided. The session keys used for this object have to be provided by the EAP method. For this version of the document it is assumed that no negotiation of algorithms and parameters takes place. Instead HMAC-SHA1 is used by default. A different algorithm may be chosen by default in a future version of the PANA protocol specification. The used algorithm is indicated in the header of the Integrity object. To select the security association for signaling message protection the Session ID is conveyed. The keyed message digest included in the Integrity object will include all fields of the PANA signaling message including the sequence number fields of the packet. The protection of subsequent signaling messages prevents an adversary from acting as a man-in-the-middle adversary, from injecting packets, from replaying messages and from modifying the content of the exchanged packets. This prevents subsequently described threats. If an entity (PAA or PaC) loses its state (especially the current sequence number) then the entire PANA protocol has to be restarted. No re-synchronization procedure is provided. The lifetime of the PANA SA has to be bound to the AAA-authorized session lifetime with an additional tolerance period. Unless PANA state is updated by executing another EAP authentication, PANA SA is removed when the current session expires. The lifetime of the PANA SA has to be bound to the AAA-authorized session lifetime with an additional tolerance period. Unless PANA state is updated by executing another EAP authentication, PANA SA is removed when the current session expires. d) Enabling weak legacy authentication methods in insecure networks Forsberg, et al. Expires January 15, 2005 [Page 65] Internet-Draft PANA July 2004 Some of the authentication methods are not strong enough to be used in insecure networks where attackers can easily eavesdrop and spoof on the link. They may not be able to produce much needed keying material either. An example would be using EAP-MD5 over wireless links. Use of such legacy methods can be enabled by carrying them over a secure channel. There are EAP methods which are specifically designed for this purpose, such as EAP-TTLS [I-D.ietf-pppext-eap-ttls],PEAP [I-D.josefsson-pppext-eap-tls-eap] or EAP-IKEv2 [I-D.tschofenig-eap-ikev2]. PANA can carry these EAP tunneling methods which can carry the legacy methods. PANA does not do anything special for this case. The EAP tunneling method will have to produce keying material for PANA SA when needed. There are certain MitM vulnerabilities with tunneling EAP methods [mitm]. Solving these problems is outside the scope of PANA. The compound authentication problem described in [I-D.puthenkulam-eap-binding] is likely to be solved in EAP itself rather than in PANA. e) Device Identifier exchange As part of the authorization procedure a Device Identifier has to be installed at the EP by the PAA. The PaC provides the Device Identifier information to the PAA secured with the PANA SA. Section 6.2.4 of [I-D.ietf-pana-threats-eval] describes a threat where an adversary modifies the Device Identifier to gain unauthorized access to the network. The installation of the Device Identifier at the EP (independently whether the EP is co-located with the PAA or not) has to be accomplished in a secure manner. These threats are, however, not part of the PANA protocol itself since the protocol is not PANA specific. f) Triggering a data protection protocol Recent activities in the EAP working group try to create a common framework for key derivation which is described in [I-D.ietf-eap-keying]. This framework is also relevant for PANA in various ways. First, a PANA security association needs to be created. Additionally it might be necessary to trigger a protocol which allows link layer and network layer data protection to be established. As an example see Section 1 of [I-D.ietf-eap-keying] with [802.11i] and [802.11] as an example. Furthermore, a derived session key might help to create the pre-requisites for network-layer protection (for example IPsec [I-D.ietf-pana-ipsec]). As motivated in Section 6.4 of [I-D.ietf-pana-threats-eval] it might be necessary to establish either a link layer or a network layer protection to prevent certain thefts in certain scenarios. Forsberg, et al. Expires January 15, 2005 [Page 66] Internet-Draft PANA July 2004 Threats specific to the establishment of a link layer or a network layer security association are outside the scope of PANA. The interested reader should refer to the relevant working groups such as IPsec or Midcom. g) Liveness test Network access authentication is done for a very specific purpose and often charging procedures are involved which allow restricting network resource usage based on some policies. In mobile environments it is always possible that an end host suddenly disconnects without transmitting a disconnect message. Operators are generally motivated to detect a disconnected end host as soon as possible in order to release resources (i.e., garbage collection). The PAA can remove per-session state information including installed security association, packet filters, etc. Different procedures can be used for disconnect indication. PANA cannot assume link-layer disconnect indication. Hence this functionality has to be provided at a higher layer. With this version of the draft we suggest to apply the soft-state principle found at other protocols (such as RSVP). Soft-state means that session state is kept alive as long as refresh messages refresh the state. If no new refresh messages are provided then the state automatically times out and resources are released. This process includes stopping accounting procedures. A PANA session is associated with a session lifetime. The session is terminated unless it is refreshed by a new round of EAP authentication before it expires. Therefore, at the latest a disconnected client can be detected when its lifetime expires. A disconnect may also be detected earlier by using PANA reauthentication messages. A request message can be generated by either PaC or PAA at any time and the peer must respond with an answer message. A successful round-trip of this exchange is a simple verification that the peer is alive. This test can be engaged when there is a possibility that the peer might have disconnected (e.g., after discontinuation of data traffic). Periodic use of this exchange as a keep-alive requires additional care as it might result in congestion and hence false alarms. This exchange is cryptographically protected when PANA SA is available in order to prevent threats associated with the abuse of this functionality. h) Tear-Down message The PANA protocol supports the ability for both the PaC and the PAA to transmit a tear-down message. This message causes state removal, a stop of the accounting procedure and removes the installed packet Forsberg, et al. Expires January 15, 2005 [Page 67] Internet-Draft PANA July 2004 filters. It is obvious that such a message must be protected to prevent an adversary from deleting state information and thereby causing denial of service attacks. i) Mobility optimization The mobility optimization described in Section 4.12 involves the previous PAA providing a AAA-Key to the current PAA of the PaC. There are security risks stemming from potential compromise of PAAs. Compromise of the current PAA does not yield compromise of the previous PAA, as AAA-Key cannot be computed from a compromised AAA-Key-new. But a compromised previous PAA along with the intercepted nonce values leads to the compromise of AAA-Key-new. Operators should be aware of the potential risk of using this optimization. An operator can reduce the risk exposure by forcing the PaC to perform an EAP-based authentication immediately after the optimized PANA execution. j) Updating PaC's address An attacker can generate a PANA-Update-Request with an IP-Address AVP. There are several threats: o An attacker spoofs an address and registers itself with the address. If the registered address is not assigned to any PaC, subsequent PANA messages sent from the PAA to the attacker will not reach any node and this is not a significant harm. If the registered address is assigned to some PaC, subsequent PANA messages sent from the PAA to the attacker will reach the PaC, but will be silently discarded because the Session-Id is different. o An attacker registers other PaC with any address. As a result, subsequent PANA messages sent from the PAA to the PaC will not reach the PaC. To avoid all those attacks against an address update, an additional mechanism may be defined outside the PANA protocol for the PAA to validate ownership of the address. Forsberg, et al. Expires January 15, 2005 [Page 68] Internet-Draft PANA July 2004 10. Open Issues and Change History A list of open issues is maintained at [2]. Issues incorporated in PANA-01 June 2003: 1, 3, 10, 5, 6, 7 and 11. Issues incorporated in PANA-02 October 2003: 8, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 30, 31, 32 and 33. Issues incorporated in PANA-03 February 2004: 2, 16, 34, 35, 36, 38, 39, 40, 42, 43, 44, 50, 51 and 60. Issues incorporated in PANA-04 May 2004: 28, 52, 53, 56, 57, 58, 59, 61, 62, 63, 64, 65, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80 and 83. Issues incorporated in PANA-05 July 2004: 84, 85, 91, 92, 93, 96, 97, 98, 99, 100, 103 and 107. Forsberg, et al. Expires January 15, 2005 [Page 69] Internet-Draft PANA July 2004 11. Acknowledgments We would like to thank Jari Arkko, Mohan Parthasarathy, Julien Bournelle, Rafael Marin Lopez, Pasi Eronen, Randy Turner, Erik Nordmark and all members of the PANA working group for their valuable comments to this document. Forsberg, et al. Expires January 15, 2005 [Page 70] Internet-Draft PANA July 2004 12. References 12.1 Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, August 1996. [RFC2988] Paxson, V. and M. Allman, "Computing TCP's Retransmission Timer", RFC 2988, November 2000. [RFC2234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. [RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G. and J. Arkko, "Diameter Base Protocol", RFC 3588, September 2003. [RFC2462] Thomson, S. and T. Narten, "IPv6 Stateless Address Autoconfiguration", RFC 2462, December 1998. [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks", RFC 2464, December 1998. [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. [RFC3456] Patel, B., Aboba, B., Kelly, S. and V. Gupta, "Dynamic Host Configuration Protocol (DHCPv4) Configuration of IPsec Tunnel Mode", RFC 3456, January 2003. [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J. and H. Levkowetz, "Extensible Authentication Protocol (EAP)", RFC 3748, June 2004. [I-D.ietf-eap-keying] Aboba, B., "Extensible Authentication Protocol (EAP) Key Management Framework", draft-ietf-eap-keying-02 (work in progress), June 2004. [IANA] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. Forsberg, et al. Expires January 15, 2005 [Page 71] Internet-Draft PANA July 2004 12.2 Informative References [I-D.ietf-pana-requirements] Yegin, A. and Y. Ohba, "Protocol for Carrying Authentication for Network Access (PANA)Requirements", draft-ietf-pana-requirements-08 (work in progress), June 2004. [I-D.ietf-aaa-eap] Eronen, P., Hiller, T. and G. Zorn, "Diameter Extensible Authentication Protocol (EAP) Application", draft-ietf-aaa-eap-08 (work in progress), June 2004. [I-D.puthenkulam-eap-binding] Puthenkulam, J., "The Compound Authentication Binding Problem", draft-puthenkulam-eap-binding-04 (work in progress), October 2003. [RFC2522] Karn, P. and W. Simpson, "Photuris: Session-Key Management Protocol", RFC 2522, March 1999. [I-D.ietf-pana-threats-eval] Parthasarathy, M., "Protocol for Carrying Authentication and Network Access Threat Analysis and Security Requirements", draft-ietf-pana-threats-eval-06 (work in progress), June 2004. [I-D.ietf-pana-ipsec] Parthasarathy, M., "PANA enabling IPsec based Access Control", draft-ietf-pana-ipsec-03 (work in progress), May 2004. [I-D.ietf-pana-framework] Jayaraman, P., "PANA Framework", draft-ietf-pana-framework-00 (work in progress), May 2004. [I-D.ietf-pana-snmp] Mghazli, Y., Ohba, Y. and J. Bournelle, "SNMP usage for PAA-2-EP interface", draft-ietf-pana-snmp-00 (work in progress), April 2004. [I-D.irtf-aaaarch-handoff] Arbaugh, W. and B. Aboba, "Experimental Handoff Extension to RADIUS", draft-irtf-aaaarch-handoff-04 (work in progress), November 2003. [I-D.ietf-eap-statemachine] Vollbrecht, J., Eronen, P., Petroni, N. and Y. Ohba, Forsberg, et al. Expires January 15, 2005 [Page 72] Internet-Draft PANA July 2004 "State Machines for Extensible Authentication Protocol (EAP) Peer and Authenticator", draft-ietf-eap-statemachine-03 (work in progress), March 2004. [I-D.ietf-seamoby-ctp] Loughney, J., "Context Transfer Protocol", draft-ietf-seamoby-ctp-10 (work in progress), June 2004. [RFC2716] Aboba, B. and D. Simon, "PPP EAP TLS Authentication Protocol", RFC 2716, October 1999. [I-D.ietf-ipsec-ikev2] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", draft-ietf-ipsec-ikev2-14 (work in progress), June 2004. [I-D.josefsson-pppext-eap-tls-eap] Josefsson, S., Palekar, A., Simon, D. and G. Zorn, "Protected EAP Protocol (PEAP)", draft-josefsson-pppext-eap-tls-eap-07 (work in progress), October 2003. [I-D.ietf-pppext-eap-ttls] Funk, P. and S. Blake-Wilson, "EAP Tunneled TLS Authentication Protocol (EAP-TTLS)", draft-ietf-pppext-eap-ttls-04 (work in progress), April 2004. [I-D.tschofenig-eap-ikev2] Tschofenig, H. and D. Kroeselberg, "EAP IKEv2 Method (EAP-IKEv2)", draft-tschofenig-eap-ikev2-03 (work in progress), February 2004. [ianaweb] IANA, "Number assignment", http://www.iana.org. [jb99] Juels, A. and J. Brainard, "Client Puzzles: A Cryptographic Defense Against Connection Depletion Attacks", Proceedings of NDSS '99 (Networks and Distributed Security Systems), pages 151-165, 1999. [mitm] Asokan, N., Niemi, V. and K. Nyberg, "Man-in-the-middle in tunnelled authentication", In the Proceedings of the 11th International Workshop on Security Protocols, Cambridge, UK, April 2003. [802.11i] Institute of Electrical and Electronics Engineers, "Draft supplement to standard for telecommunications and information exchange between systems - lan/man specific Forsberg, et al. Expires January 15, 2005 [Page 73] Internet-Draft PANA July 2004 requirements - part 11: Wireless medium access control (mac) and physical layer (phy) specifications: Specification for enhanced security", IEEE 802.11i/D10.0, 2004. [802.11] Institute of Electrical and Electronics Engineers, "Information technology - telecommunications and information exchange between systems - local and metropolitan area networks - specific requirements part 11: Wireless lan medium access control (mac) and physical layer (phy) specifications", IEEE Standard 802.11, 1999(R2003). [IANA-EXP] Narten, T., "Assigning Experimental and Testing Numbers Considered Useful", BCP 82, RFC 3692, January 2004. Forsberg, et al. Expires January 15, 2005 [Page 74] Internet-Draft PANA July 2004 URIs [1] [2] Authors' Addresses Dan Forsberg Nokia Research Center P.O. Box 407 FIN-00045 NOKIA GROUP Finland Phone: +358 50 4839470 EMail: dan.forsberg@nokia.com Yoshihiro Ohba Toshiba America Research, Inc. 1 Telcordia Drive Piscataway, NJ 08854 USA Phone: +1 732 699 5305 EMail: yohba@tari.toshiba.com Basavaraj Patil Nokia 6000 Connection Dr. Irving, TX 75039 USA Phone: +1 972-894-6709 EMail: Basavaraj.Patil@nokia.com Hannes Tschofenig Siemens Corporate Technology Otto-Hahn-Ring 6 81739 Munich Germany EMail: Hannes.Tschofenig@siemens.com Forsberg, et al. Expires January 15, 2005 [Page 75] Internet-Draft PANA July 2004 Alper E. Yegin Samsung Advanced Institute of Technology 75 West Plumeria Drive San Jose, CA 95134 USA Phone: +1 408 544 5656 EMail: alper.yegin@samsung.com Forsberg, et al. 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Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Forsberg, et al. Expires January 15, 2005 [Page 77]