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Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC2464' is defined on line 332, but no explicit reference was found in the text ** Downref: Normative reference to an Informational RFC: RFC 5193 -- Obsolete informational reference (is this intentional?): RFC 3344 (Obsoleted by RFC 5944) Summary: 2 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Yegin 3 Internet-Draft Samsung 4 Intended status: Standards Track Y. Ohba 5 Expires: March 31, 2011 Toshiba 6 L. Morand 7 Orange Labs 8 J. Kaippallimalil 9 Huawei USA 10 September 27, 2010 12 Protocol for Carrying Authentication for Network Access (PANA) with IPv4 13 Unspecified Address 14 draft-yegin-pana-unspecified-addr-03 16 Abstract 18 This document defines how PANA client (PaC) can perform PANA 19 authentication prior to configuring an IP address. 21 Status of this Memo 23 This Internet-Draft is submitted to IETF in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on March 31, 2011. 38 Copyright Notice 40 Copyright (c) 2010 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 56 1.1. Specification of Requirements . . . . . . . . . . . . . . . 3 57 2. Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 3. PaC Behavior . . . . . . . . . . . . . . . . . . . . . . . . . 5 59 4. PAA Behavior . . . . . . . . . . . . . . . . . . . . . . . . . 6 60 5. AVP Definition . . . . . . . . . . . . . . . . . . . . . . . . 6 61 5.1. Token AVP . . . . . . . . . . . . . . . . . . . . . . . . . 6 62 6. Message Size Considerations . . . . . . . . . . . . . . . . . . 6 63 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 64 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 65 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 8 66 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 67 10.1. Normative References . . . . . . . . . . . . . . . . . . . 8 68 10.2. Informative References . . . . . . . . . . . . . . . . . . 8 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 71 1. Introduction 73 PANA (Protocol for carrying Authentication for Network Access) 74 [RFC5191] as a UDP-based protocol operates with the assumption that 75 the PANA client (PaC) is already configured with an IP address. 76 Private IPv4, globally-routable IPv4 [RFC1918] or IPv6, IPv4 or IPv6 77 link-local are the types of addresses that can be configured by PaCs 78 prior to running PANA [RFC5193]. 80 In case the PaC and the PANA Authentication Agent (PAA) are on the 81 same IP subnet where all hosts in the subnet can be reached in one 82 routing hop, the PaC can run PANA with the PAA prior to configuring 83 an IP address. 85 This document defines an extension of PANA to allow the PaC to use 86 IPv4 unspecified address (0.0.0.0) until it gets authenticated/ 87 authorized; and configures an IP address afterwards (possibly using 88 DHCP). Such a feature is already available in Mobile IPv4 [RFC3344] 89 where MN can use unspecified IPv4 address with Mobile IP protocol 90 until it is assigned a home address, and also DHCP [RFC2131]. 92 This extension is defined only as a solution for use cases in which 93 PANA authentication is required prior to any kind of IP address 94 allocation or configuration. It is not intended to become the 95 default mode of operation for PANA. 97 1.1. Specification of Requirements 99 In this document, several words are used to signify the requirements 100 of the specification. These words are often capitalized. The key 101 words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", 102 "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document 103 are to be interpreted as described in [RFC2119]. 105 2. Details 107 Figure 1 is an example call flow that illustrates use of unspecified 108 IPv4 address with the PaC during PANA authentication. Note that 109 there can be other ways for combining DHCP and PANA call flows. 111 PaC PAA AAA 113 | | | 114 | | | 115 | | | 116 |--1. PANA Client initiation(Token)->| | 117 | | | 118 |<-2. PANA Auth Req(Token)-----------| | 119 | | | 120 |--3. PANA Auth Ans ---------------->| | 121 | | | 122 | |-4. RADIUS Access ->| 123 | | Request (EAP) | 124 | | | 125 | |<-5. RADIUS Access--| 126 | | (EAP Success) | 127 |<-6. PANA Auth Req -----------------| | 128 | | | 129 |--7. PANA Auth Ans ---------------->| | 130 | | | 131 |--8. DHCP Discover----------------->| | 132 | | | 133 |<-9. DHCP Offer---------------------| | 134 | | | 135 |--10. DHCP Request----------------->| | 136 | | | 137 |<-11. DHCP Ack----------------------| | 138 | | | 139 |<-12. IP session data traffic----------------> | 140 | | | 142 Figure 1: Example Call Flow for PANA with IPv4 Unspecified Address 144 Step 1: The PaC initiates PANA by sending a broadcasted PCI carrying 145 a Token AVP that contains a random value generated by the PaC. 147 The source IPv4 address of the PCI is set to 0.0.0.0. The 148 destination IPv4 address is set to 255.255.255.255. 150 Step 2: The PAA responds with a PAR message that includes the token 151 generated by the PaC. The PAR message has its source IPv4 address 152 set to the PAA's IP address, and the destination IPv4 address is set 153 to 255.255.255.255. If the PAA is capable of retrieving the PaC's L2 154 address from incoming PCI, then the PAR is L2-unicast using that L2 155 address. Otherwise, the PAR message will be L2-broadcast. 157 The PaC discovers the PAA's IPv4 address when it receives the PAR 158 message. 160 Step 3: The PaC sends the PAN message to the PAA's newly discovered 161 IPv4 address. 163 Steps 4-7: PANA and RADIUS carrying out the selected EAP method. 165 Steps 8-11: Now that the PaC is authenticated, it proceeds to 166 configuring service IP address using DHCPv4. As soon as the new IPv4 167 address is confirmed by the DHCPACK, the PaC can stop using the 168 unspecified address. 170 Step 12: The PaC can transmit and receive IP data packets using its 171 IP address. 173 A PAA implementation may not be capable of retrieving the PaC's L2 174 address from L2 header of the incoming PANA messages, or be able to 175 send a L2-unicast even if it could retrieve the address. In such a 176 case, the PAA sends PANA messages as L2-broadcast. In order to 177 prevent other PaCs from processing the messages destined for a 178 specific PaC, each PaC is required to supply a randomly generated 179 token as a payload AVP to PCI and expect it to be echoed back by the 180 PAA in the initial PAR. Token AVP is defined for this purpose. 182 Note that any message beyond Step 2 would include the PAA-assigned 183 and PaC-acknowledged PANA Session Id, hence use of Token AVP is not 184 needed for those messages. 186 3. PaC Behavior 188 A PaC SHALL use unspecified address as its source IP address until it 189 configures another IP address. The PaC SHALL send a PCI carrying a 190 Token AVP. The PaC SHOULD NOT include a Token AVP in any other 191 message. 193 The PaC SHALL silently drop any PAR that carries a Token AVP whose 194 token value does not match the one contained in the PCI sent by the 195 PaC. 197 The PaC, before it sends the first PAN to the PAA, SHALL silently 198 drop any PAR that is L2-broadcast and without carrying a Token AVP. 200 Any legacy PaC that does not implement this specification will 201 automatically drop the incoming PAR that carries the Token AVP as 202 this is an unrecognized AVP. This is the standard behavior defined 203 in [RFC5191]. 205 4. PAA Behavior 207 If a PAA receives a PCI whose source IP address is unspecified but 208 that does not carry a Token AVP, then it SHALL drop the PCI. The PAA 209 SHALL ignore a Token AVP if it is contained in any message other than 210 PCI. 212 When the PAA needs to send a packet to a PaC that is using an 213 unspecified IP address, then the PAA shall set the destination IP 214 address to 255.255.255.255. The PAA SHOULD set the destination L2 215 address to the source L2 address retrieved from the incoming PaC 216 packet, when possible; otherwise set to L2 broadcast address. If 217 this is the very first PAR message sent to L2 broadcast address in 218 response to a PCI message containing a Token AVP, then the PAA SHALL 219 include a Token AVP copied from the PCI. The PAA SHOULD NOT include 220 a Token AVP in any other PANA message, as an already-assigned PANA 221 Session Id serves the need. 223 The PAA SHALL set the 'I' (IP Reconfiguration) bit of PAR messages in 224 authentication and authorization phase so that the PaC proceeds to IP 225 address configuration. 227 Any legacy PAA that does not implement this specification would 228 automatically drop the incoming PCI that carries the Token AVP as 229 this is an unrecognized AVP. This is the standard behavior defined 230 in [RFC5191]. 232 5. AVP Definition 234 This document defines one new AVP as described below. 236 5.1. Token AVP 238 The Token AVP (AVP Code TBD) is of type Unsigned64 containing a 239 random value generated by the PaC. 241 6. Message Size Considerations 243 Since IP fragmentation for IP packets using unspecified address is 244 prohibited, link-layer MTU needs to be no less than the IP packet 245 size carrying the largest PANA message in the case where EAP message 246 size is the same as the minimum EAP MTU size (i.e., 1020 octets 247 [RFC3748]). Such a PANA message is the very first PANA-Auth-Request 248 message in Authentication and Authorization phase carrying the 249 following AVPs. 251 o An EAP-Payload AVP that carries an EAP-Request of size being equal 252 to the minimum EAP MTU size. The size of such an AVP is 1020 + 8 253 = 1028 octets. 255 o A Nonce AVP that carries the largest nonce of size 256 octets. 256 The size of such an AVP is 256 + 8 = 264 octets. 258 o An Integrity-Algorithm AVP (12 octets) 260 o A PRF-Algorithm AVP (12 octets) 262 o A Token AVP (16 octets) 264 In this case, the PANA message size including PANA header (16 265 octets), UDP header (8 octets) and IPv4 header (20 octets) is 1028 + 266 264 + 12 + 12 + 16 + 16 + 8 + 20 = 1376 octets. Therefore, the link- 267 layer MTU size for IP packets MUST be no less than 1376 octets when 268 unspecified IPv4 address is used for PANA. Note that Ethernet (MTU = 269 1500 octets) meets this requirement. 271 PANA as an EAP lower-layer reports the EAP MTU to the EAP layer, so 272 that EAP methods can perform appropriate fragmentation [RFC3748]. 273 The EAP MTU is calculated as follows: 275 EAP_MTU = L2_MTU - 356 277 In the above formula, the value of 356 is the PANA overhead (IP, UDP 278 and PANA headers, and PANA AVPs except for the EAP-Payload AVP 279 payload). 281 7. Security Considerations 283 When the PAA is not capable of L2-unicasting PANA messages to the 284 target PaC, other nodes on the same subnet can receive those 285 messages. This may pose a risk if there is any confidential data 286 exposed in the messages. Typically no such exposure exists as PANA, 287 EAP, an EAP methods are defined in a way they can also be used in 288 wireless networks where snooping is always a possibility. 290 8. IANA Considerations 292 As described in Section 5.1 and following the new IANA allocation 293 policy on PANA message [RFC5872], a new AVP Code for Token AVP needs 294 to be assigned by IANA. 296 9. Acknowledgments 298 TBD. 300 10. References 302 10.1. Normative References 304 [RFC5191] Forsberg, D., Ohba, Y., Patil, B., Tschofenig, H., and A. 305 Yegin, "Protocol for Carrying Authentication for Network 306 Access (PANA)", RFC 5191, May 2008. 308 [RFC5193] Jayaraman, P., Lopez, R., Ohba, Y., Parthasarathy, M., and 309 A. Yegin, "Protocol for Carrying Authentication for 310 Network Access (PANA) Framework", RFC 5193, May 2008. 312 [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. 313 Levkowetz, "Extensible Authentication Protocol (EAP)", 314 RFC 3748, June 2004. 316 [RFC5872] Arkko, J. and A. Yegin, "IANA Rules for the Protocol for 317 Carrying Authentication for Network Access (PANA)", 318 RFC 5872, May 2010. 320 10.2. Informative References 322 [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and 323 E. Lear, "Address Allocation for Private Internets", 324 BCP 5, RFC 1918, February 1996. 326 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 327 Requirement Levels", BCP 14, RFC 2119, March 1997. 329 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 330 RFC 2131, March 1997. 332 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 333 Networks", RFC 2464, December 1998. 335 [RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, 336 August 2002. 338 Authors' Addresses 340 Alper Yegin 341 Samsung 342 Istanbul 343 Turkey 345 Email: alper.yegin@yegin.org 347 Yoshihiro Ohba 348 Toshiba Corporate Research and Development Center 349 1 Komukai-Toshiba-cho 350 Saiwai-ku, Kawasaki, Kanagawa 212-8582 351 Japan 353 Phone: +81 44 549 2230 354 Email: yoshihiro.ohba@toshiba.co.jp 356 Lionel Morand 357 Orange Labs 359 Phone: +33 1 4529 62 57 360 Email: Lionel.morand@orange-ftgroup.com 362 John Kaippallimalil 363 Huawei USA 364 1700 Alma Dr., Suite 500 365 Plano, TX 75082 366 USA 368 Phone: +1 214 606 2005 369 Email: jkaippal@huawei.com