idnits 2.17.1 draft-nir-ipsecme-erx-05.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- == There are 1 instance of lines with non-RFC6890-compliant IPv4 addresses in the document. If these are example addresses, they should be changed. -- The draft header indicates that this document updates RFC5996, but the abstract doesn't seem to mention this, which it should. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year (Using the creation date from RFC5996, updated by this document, for RFC5378 checks: 2008-08-26) -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (July 30, 2012) is 4288 days in the past. Is this intentional? Checking references for intended status: Experimental ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 5996 (Obsoleted by RFC 7296) -- Obsolete informational reference (is this intentional?): RFC 3588 (Obsoleted by RFC 6733) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Y. Nir 3 Internet-Draft Check Point 4 Updates: 5996 (if approved) Q. Wu 5 Intended status: Experimental Huawei 6 Expires: January 31, 2013 July 30, 2012 8 An IKEv2 Extension for Supporting ERP 9 draft-nir-ipsecme-erx-05 11 Abstract 13 This document describes an extension to the IKEv2 protocol that 14 allows an IKE Security Association (SA) to be created and 15 authenticated using the EAP Re-authentication Protocol extension as 16 described in RFC 6696. 18 Status of this Memo 20 This Internet-Draft is submitted in full conformance with the 21 provisions of BCP 78 and BCP 79. 23 Internet-Drafts are working documents of the Internet Engineering 24 Task Force (IETF). Note that other groups may also distribute 25 working documents as Internet-Drafts. The list of current Internet- 26 Drafts is at http://datatracker.ietf.org/drafts/current/. 28 Internet-Drafts are draft documents valid for a maximum of six months 29 and may be updated, replaced, or obsoleted by other documents at any 30 time. It is inappropriate to use Internet-Drafts as reference 31 material or to cite them other than as "work in progress." 33 This Internet-Draft will expire on January 31, 2013. 35 Copyright Notice 37 Copyright (c) 2012 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (http://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with respect 45 to this document. Code Components extracted from this document must 46 include Simplified BSD License text as described in Section 4.e of 47 the Trust Legal Provisions and are provided without warranty as 48 described in the Simplified BSD License. 50 1. Introduction 52 IKEv2, as specified in section 2.16 of [RFC5996], allows 53 authentication of the initiator using an EAP method. Using EAP 54 significantly increases the count of round-trips required to 55 establish the IPsec SA, and also may require user interaction. This 56 makes it inconvenient to allow a single remote access client to 57 create multiple IPsec tunnels with multiple IPsec gateways that 58 belong to the same domain. 60 The EAP Re-authentication Protocol (ERP), as described in [RFC6696], 61 allows an EAP peer to authenticate to multiple authenticators, while 62 performing the full EAP method only once. Subsequent authentications 63 require fewer round-trips and no user interaction. 65 Bringing these two technologies together allows a remote access IPsec 66 client to create multiple tunnels with different gateways that belong 67 to a single domain, as well as using the keys from other contexts of 68 using EAP, such as network access within the same domain, to 69 transparently connect to VPN gateways within this domain. 71 1.1. Conventions Used in This Document 73 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 74 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 75 document are to be interpreted as described in [RFC2119]. 77 2. Usage Scenarios 79 This work is motivated by the following scenarios: 80 o Multiple tunnels for a single remote access VPN client. Suppose a 81 company has offices in New York City, Paris, and Shanghai. For 82 historical reasons, the email server is located in the Paris 83 office, while most of the servers hosting the company's intranet 84 are located in Shanghai, and the finance department servers are in 85 NYC. An employee using remote access VPN may need to connect to 86 servers from all three locations. While it is possible to connect 87 to a single gateway, and have that gateway route the requests to 88 the other gateways (perhaps through site to site VPN), this is not 89 efficient, and it is more desirable to have the client initiate 90 three different tunnels. It is, however, not desirable to have 91 the user type in a password three times. 92 o Roaming. In these days of mobile phones and tablets, users often 93 move from the wireless LAN in their office, where access may be 94 granted through 802.1x, to a cellular network where VPN is 95 necessary and back again. Both the VPN server and the 802.1x 96 access point are authenticators that connect to the same 97 Authentication, Authorization and Accounting (AAA) servers. So it 98 makes sense to make the transition smooth, without requiring user 99 interaction. The device still needs to detect whether it is 100 within the protected network, in which case it should not use VPN, 101 but this process is beyond the scope of this document. 102 [SecureBeacon] is a now-abandoned attempt at this. 104 3. Protocol Outline 106 Supporting ERX requires an EAP payload in the first IKE_AUTH request. 107 This is a deviation from the rules in RFC 5996, so support needs to 108 be indicated through a Notify payload in the IKE_SA_INIT response. 109 This Notify serves the same purpose as the EAP-Initiate/Re-auth-Start 110 message of ERX, as specified in section 5.3.1 of [RFC6696]. The 111 domain name included in the Domain-Name TLV as specified in section 112 5.3.1.1 of the same document. 114 A supporting initiator that has unexpired keys for this domain will 115 send the EAP_Initiate/Re-auth message in an EAP payload in the first 116 IKE_AUTH request. 118 The responder sends the EAP payload content to a backend AAA server, 119 and receives the rMSK and an EAP-Finish/Re-auth message. It then 120 forwards the EAP-Finish/Re-auth message to the Initiator in an EAP 121 payload within the first IKE_AUTH response. 123 The initiator then sends an additional IKE_AUTH request, that 124 includes the AUTH payload which has been calculated using the rMSK in 125 the role of the MSK as described in sections 2.15 and 2.16 of 126 [RFC5996]. The responder replies similarly, and the IKE_AUTH 127 exchange is finished. 129 The following figure is adapted from appendixes C.1 and C.3 of RFC 130 5996, with most of the optional payloads removed. Note that the 131 EAP_Initiate/Re-auth message is added. 133 IKE_SA_INIT Exchange: 134 | init request --> SA, KE, Ni, 135 | 136 | init response <-- SA, KE, Nr, 137 | N[ERX_SUPPORTED] 139 IKE_AUTH Exchanges: 140 | first request --> EAP(EAP_Initiate/Re-auth), 141 | IDi, 142 | SA, TSi, TSr 143 | 144 | first response <-- IDr, [CERT+], AUTH, 145 | EAP(EAP-Finish/Re-auth) 146 | 147 | last request --> AUTH 148 | 149 | last response <-- AUTH, 150 | SA, TSi, TSr 152 The IDi payload MUST have ID Type ID_RFC822_ADDR and the data field 153 MUST contain the same value as the KeyName-NAI TLV in the 154 EAP_Initiate/Re-auth message. See Section 3.2 for details. 156 3.1. Clarification About EAP Codes 158 Section 3.16 of RFC 5996 enumerates the EAP codes in EAP messages 159 which are carried in EAP payloads. The enumeration goes only to 4. 160 It is not clear whether that list is supposed to be exhaustive or 161 not. 163 To clarify, an implementation conforming to this specification MUST 164 accept and transmit EAP messages with at least the codes for Initiate 165 and Finish (5 and 6) from [RFC6696], in addition to the four codes 166 enumerated in RFC 5996. This document is intentionally silent about 167 other EAP codes that are neither enumerated in RFC 5996 nor in that 168 document. 170 3.2. User Name in the Protocol 172 The authors, as well as participants of the HOKEY and IPsecME working 173 groups believe that all use cases for this extension to IKE have a 174 single backend AAA server doing both the authentication and the re- 175 authentication. The reasoning behind this is that IKE runs over the 176 Internet, and would naturally connect to the user's home network. 178 This section addresses instances where this is not the case. 180 Section 5.3.2 of [RFC6696] describes the EAP-Initiate/Re-auth packet, 181 which in the case of IKEv2 is carried in the first IKE_AUTH request. 182 This packet contains the KeyName-NAI TLV. This TLV contains the 183 username used in authentication. It is relayed to the AAA server in 184 the AccessRequest message, and is returned from the AAA server in the 185 AccessAccept message. 187 The username part of the NAI within the TLV is the EMSKName 188 ([RFC5295] encoded in hexadecimal digits. The domain part is the 189 domain name of the home domain of the user. The username part is 190 ephemeral in the sense that a new one is generated for each full 191 authentication. This ephemeral value is not a good basis for making 192 policy decisions, and they are also a poor source of user 193 identification for the purposes of logging. 195 Instead, it is up to the implementation in the IPsec gateway to make 196 policy decisions based on other factors. The following list is by no 197 means exhaustive: 198 o In some cases the home domain name may be enough to make policy 199 decisions. If all users with a particular home domain get the 200 same authorization, then policy does not depend on the real user 201 name. Meaningful logs can still be issued by correlating VPN 202 gateway IKE events with AAA servers access records. 203 o Sometimes users receive different authorizations based on groups 204 they belong to. The AAA server can communicate such information 205 to the VPN gateway, for example using the CLASS attribute 206 ([RFC2865]) in RADIUS and Diameter ([RFC3588]). Logging again 207 depends on correlation with AAA servers. 208 o AAA servers may support extensions that allow them to communicate 209 with their clients (in our case - the VPN gateway) to push user 210 information. For example, a certain product integrates a RADIUS 211 server with the Lightweight Directory Access Protocol (LDAP - 212 [RFC4511]), so a client could query the server using LDAP and 213 receive the real record for this user. Others may provide this 214 data through vendor-specific extensions to RADIUS or DIAMETER. 216 In any case authorization is a major issue in deployments, if the 217 backend AAA server supporting the re-authentication is different from 218 the AAA server that had supported the original authentication. It is 219 up to the re-authenticating AAA server to provide the necessary 220 information for authorization. A conforming implementation of this 221 protocol MAY reject initiators for which it is unable to make policy 222 decisions because of these reasons. 224 4. ERX_SUPPORTED Notification 226 The Notify payload is as described in RFC 5996: 228 1 2 3 229 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 1 230 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 231 ! Next Payload !C! RESERVED ! Payload Length ! 232 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 233 ! Protocol ID ! SPI Size ! ERX Notify Message Type ! 234 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 235 ! Domain Name ! 236 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 238 o Protocol ID (1 octet) MUST be 1, as this message is related to an 239 IKE SA. 240 o SPI Size (1 octet) MUST be zero, in conformance with section 3.10 241 of [RFC5996]. 242 o ERX Notify Message Type (2 octets) - MUST be xxxxx, the value 243 assigned for ERX. TBA by IANA. 244 o Domain Name (variable) - contains the domain name or realm, as 245 these terms are used in [RFC6696], and encoded as UTF-8. 247 5. Security Considerations 249 The protocol extension described in this document extends the 250 authentication from one EAP context, which may or may not be part of 251 IKEv2, to an IKEv2 context. Successful completion of the protocol 252 proves to the authenticator, which in our case is a VPN gateway, that 253 the supplicant, or VPN client, has authenticated in some other EAP 254 context. 256 The protocol supplies the authenticator with the domain name with 257 which the supplicant has authenticated, but does not supply it with a 258 specific identity. Instead, the gateway receives an EMSKName, which 259 is an ephemeral ID. With this variant of the IKEv2 protocol, the 260 initiator never sends its real identity on the wire, while the server 261 does. This is different from the usual IKEv2 practice of the 262 initiator revealing its identity first. 264 If the domain name is sufficient to make access control decisions, 265 this is enough. If not, then the gateway needs to find out either 266 the real name or authorization information for that particular user. 267 This may be done using the AAA protocol or by some other federation 268 protocol, which is out of scope for this specification. 270 6. IANA Considerations 272 IANA is requested to assign a notify message type from the status 273 types range (16418-40959) of the "IKEv2 Notify Message Types" 274 registry with name "ERX_SUPPORTED". 276 7. Acknowledgements 278 The authors would like to thank Yaron Sheffer for comments and 279 suggested text that have contributed to this document. 281 8. References 283 8.1. Normative References 285 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 286 Requirement Levels", BCP 14, RFC 2119, March 1997. 288 [RFC5295] Salowey, J., Dondeti, L., Narayanan, V., and M. Nakhjiri, 289 "Specification for the Derivation of Root Keys from an 290 Extended Master Session Key (EMSK)", RFC 5295, 291 August 2008. 293 [RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, 294 "Internet Key Exchange Protocol: IKEv2", RFC 5996, 295 September 2010. 297 [RFC6696] Cao, Z., He, B., Shi, Y., Wu, Q., and G. Zorn, "EAP 298 Extensions for the EAP Re-authentication Protocol (ERP)", 299 RFC 6696, July 2012. 301 8.2. Informative References 303 [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, 304 "Remote Authentication Dial In User Service (RADIUS)", 305 RFC 2865, June 2000. 307 [RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. 308 Arkko, "Diameter Base Protocol", RFC 3588, September 2003. 310 [RFC4511] Sermersheim, J., "Lightweight Directory Access Protocol 311 (LDAP): The Protocol", RFC 4511, June 2006. 313 [SecureBeacon] 314 Sheffer, Y. and Y. Nir, "Secure Beacon: Securely Detecting 315 a Trusted Network", draft-sheffer-ipsecme-secure-beacon 316 (work in progress), June 2009. 318 Authors' Addresses 320 Yoav Nir 321 Check Point Software Technologies Ltd. 322 5 Hasolelim st. 323 Tel Aviv 67897 324 Israel 326 Email: ynir@checkpoint.com 328 Qin Wu 329 Huawei Technologies Co., Ltd. 330 101 Software Avenue, Yuhua District 331 Nanjing, JiangSu 210012 332 China 334 Email: sunseawq@huawei.com