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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 327, 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 14, 2011 Toshiba 6 L. Morand 7 Orange Labs 8 J. Kaippallimalil 9 Huawei USA 10 September 10, 2010 12 Protocol for Carrying Authentication for Network Access (PANA) with IPv4 13 Unspecified Address 14 draft-yegin-pana-unspecified-addr-02 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 14, 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 1.1. Specification of Requirements 94 In this document, several words are used to signify the requirements 95 of the specification. These words are often capitalized. The key 96 words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", 97 "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document 98 are to be interpreted as described in [RFC2119]. 100 2. Details 102 Figure 1 is an example call flow that illustrates use of unspecified 103 IPv4 address with the PaC during PANA authentication. Note that 104 there can be other ways for combining DHCP and PANA call flows. 106 PaC PAA AAA 108 | | | 109 | | | 110 | | | 111 |--1. PANA Client initiation(Token)->| | 112 | | | 113 |<-2. PANA Auth Req(Token)-----------| | 114 | | | 115 |--3. PANA Auth Ans ---------------->| | 116 | | | 117 | |-4. RADIUS Access ->| 118 | | Request (EAP) | 119 | | | 120 | |<-5. RADIUS Access--| 121 | | (EAP Success) | 122 |<-6. PANA Auth Req -----------------| | 123 | | | 124 |--7. PANA Auth Ans ---------------->| | 125 | | | 126 |--8. DHCP Discover----------------->| | 127 | | | 128 |<-9. DHCP Offer---------------------| | 129 | | | 130 |--10. DHCP Request----------------->| | 131 | | | 132 |<-11. DHCP Ack----------------------| | 133 | | | 134 |<-12. IP session data traffic----------------> | 135 | | | 137 Figure 1: Example Call Flow for PANA with IPv4 Unspecified Address 139 Step 1: The PaC initiates PANA by sending a broadcasted PCI carrying 140 a Token AVP that contains a random value generated by the PaC. 142 The source IPv4 address of the PCI is set to 0.0.0.0. The 143 destination IPv4 address is set to 255.255.255.255. 145 Step 2: The PAA responds with a PAR message that includes the token 146 generated by the PaC. The PAR message has its source IPv4 address 147 set to the PAA's IP address, and the destination IPv4 address is set 148 to 255.255.255.255. If the PAA is capable of retrieving the PaC's L2 149 address from incoming PCI, then the PAR is L2-unicast using that L2 150 address. Otherwise, the PAR message will be L2-broadcast. 152 The PaC discovers the PAA's IPv4 address when it receives the PAR 153 message. 155 Step 3: The PaC sends the PAN message to the PAA's newly discovered 156 IPv4 address. 158 Steps 4-7: PANA and RADIUS carrying out the selected EAP method. 160 Steps 8-11: Now that the PaC is authenticated, it proceeds to 161 configuring service IP address using DHCPv4. As soon as the new IPv4 162 address is confirmed by the DHCPACK, the PaC can stop using the 163 unspecified address. 165 Step 12: The PaC can transmit and receive IP data packets using its 166 IP address. 168 A PAA implementation may not be capable of retrieving the PaC's L2 169 address from L2 header of the incoming PANA messages, or be able to 170 send a L2-unicast even if it could retrieve the address. In such a 171 case, the PAA sends PANA messages as L2-broadcast. In order to 172 prevent other PaCs from processing the messages destined for a 173 specific PaC, each PaC is required to supply a randomly generated 174 token as a payload AVP to PCI and expect it to be echoed back by the 175 PAA in the initial PAR. Token AVP is defined for this purpose. 177 Note that any message beyond Step 2 would include the PAA-assigned 178 and PaC-acknowledged PANA Session Id, hence use of Token AVP is not 179 needed for those messages. 181 3. PaC Behavior 183 A PaC SHALL use unspecified address as its source IP address until it 184 configures another IP address. The PaC SHALL send a PCI carrying a 185 Token AVP. The PaC SHOULD NOT include a Token AVP in any other 186 message. 188 The PaC SHALL silently drop any PAR that carries a Token AVP whose 189 token value does not match the one contained in the PCI sent by the 190 PaC. 192 The PaC, before it sends the first PAN to the PAA, SHALL silently 193 drop any PAR that is L2-broadcast and without carrying a Token AVP. 195 Any legacy PaC that does not implement this specification will 196 automatically drop the incoming PAR that carries the Token AVP as 197 this is an unrecognized AVP. This is the standard behavior defined 198 in [RFC5191]. 200 4. PAA Behavior 202 If a PAA receives a PCI whose source IP address is unspecified but 203 that does not carry a Token AVP, then it SHALL drop the PCI. The PAA 204 SHALL ignore a Token AVP if it is contained in any message other than 205 PCI. 207 When the PAA needs to send a packet to a PaC that is using an 208 unspecified IP address, then the PAA shall set the destination IP 209 address to 255.255.255.255. The PAA SHOULD set the destination L2 210 address to the source L2 address retrieved from the incoming PaC 211 packet, when possible; otherwise set to L2 broadcast address. If 212 this is the very first PAR message sent to L2 broadcast address in 213 response to a PCI message containing a Token AVP, then the PAA SHALL 214 include a Token AVP copied from the PCI. The PAA SHOULD NOT include 215 a Token AVP in any other PANA message, as an already-assigned PANA 216 Session Id serves the need. 218 The PAA SHALL set the 'I' (IP Reconfiguration) bit of PAR messages in 219 authentication and authorization phase so that the PaC proceeds to IP 220 address configuration. 222 Any legacy PAA that does not implement this specification would 223 automatically drop the incoming PCI that carries the Token AVP as 224 this is an unrecognized AVP. This is the standard behavior defined 225 in [RFC5191]. 227 5. AVP Definition 229 This document defines one new AVP as described below. 231 5.1. Token AVP 233 The Token AVP (AVP Code TBD) is of type Unsigned64 containing a 234 random value generated by the PaC. 236 6. Message Size Considerations 238 Since IP fragmentation for IP packets using unspecified address is 239 prohibited, link-layer MTU needs to be no less than the IP packet 240 size carrying the largest PANA message in the case where EAP message 241 size is the same as the minimum EAP MTU size (i.e., 1020 octets 242 [RFC3748]). Such a PANA message is the very first PANA-Auth-Request 243 message in Authentication and Authorization phase carrying the 244 following AVPs. 246 o An EAP-Payload AVP that carries an EAP-Request of size being equal 247 to the minimum EAP MTU size. The size of such an AVP is 1020 + 8 248 = 1028 octets. 250 o A Nonce AVP that carries the largest nonce of size 256 octets. 251 The size of such an AVP is 256 + 8 = 264 octets. 253 o An Integrity-Algorithm AVP (12 octets) 255 o A PRF-Algorithm AVP (12 octets) 257 o A Token AVP (16 octets) 259 In this case, the PANA message size including PANA header (16 260 octets), UDP header (8 octets) and IPv4 header (20 octets) is 1028 + 261 264 + 12 + 12 + 16 + 16 + 8 + 20 = 1376 octets. Therefore, the link- 262 layer MTU size for IP packets MUST be no less than 1376 octets when 263 unspecified IPv4 address is used for PANA. Note that Ethernet (MTU = 264 1500 octets) meets this requirement. 266 PANA as an EAP lower-layer reports the EAP MTU to the EAP layer, so 267 that EAP methods can perform appropriate fragmentation [RFC3748]. 268 The EAP MTU is calculated as follows: 270 EAP_MTU = L2_MTU - 356 272 In the above formula, the value of 356 is the PANA overhead (IP, UDP 273 and PANA headers, and PANA AVPs except for the EAP-Payload AVP 274 payload). 276 7. Security Considerations 278 When the PAA is not capable of L2-unicasting PANA messages to the 279 target PaC, other nodes on the same subnet can receive those 280 messages. This may pose a risk if there is any confidential data 281 exposed in the messages. Typically no such exposure exists as PANA, 282 EAP, an EAP methods are defined in a way they can also be used in 283 wireless networks where snooping is always a possibility. 285 8. IANA Considerations 287 As described in Section 5.1 and following the new IANA allocation 288 policy on PANA message [RFC5872], a new AVP Code for Token AVP needs 289 to be assigned by IANA. 291 9. Acknowledgments 293 TBD. 295 10. References 297 10.1. Normative References 299 [RFC5191] Forsberg, D., Ohba, Y., Patil, B., Tschofenig, H., and A. 300 Yegin, "Protocol for Carrying Authentication for Network 301 Access (PANA)", RFC 5191, May 2008. 303 [RFC5193] Jayaraman, P., Lopez, R., Ohba, Y., Parthasarathy, M., and 304 A. Yegin, "Protocol for Carrying Authentication for 305 Network Access (PANA) Framework", RFC 5193, May 2008. 307 [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. 308 Levkowetz, "Extensible Authentication Protocol (EAP)", 309 RFC 3748, June 2004. 311 [RFC5872] Arkko, J. and A. Yegin, "IANA Rules for the Protocol for 312 Carrying Authentication for Network Access (PANA)", 313 RFC 5872, May 2010. 315 10.2. Informative References 317 [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and 318 E. Lear, "Address Allocation for Private Internets", 319 BCP 5, RFC 1918, February 1996. 321 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 322 Requirement Levels", BCP 14, RFC 2119, March 1997. 324 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 325 RFC 2131, March 1997. 327 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 328 Networks", RFC 2464, December 1998. 330 [RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, 331 August 2002. 333 Authors' Addresses 335 Alper Yegin 336 Samsung 337 Istanbul 338 Turkey 340 Email: alper.yegin@yegin.org 342 Yoshihiro Ohba 343 Toshiba Corporate Research and Development Center 344 1 Komukai-Toshiba-cho 345 Saiwai-ku, Kawasaki, Kanagawa 212-8582 346 Japan 348 Phone: +81 44 549 2230 349 Email: yoshihiro.ohba@toshiba.co.jp 351 Lionel Morand 352 Orange Labs 354 Phone: +33 1 4529 62 57 355 Email: Lionel.morand@orange-ftgroup.com 357 John Kaippallimalil 358 Huawei USA 359 1700 Alma Dr., Suite 500 360 Plano, TX 75082 361 USA 363 Phone: +1 214 606 2005 364 Email: jkaippal@huawei.com