idnits 2.17.1 draft-nir-ipsecme-erx-04.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 (May 21, 2012) is 4359 days in the past. 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) == Missing Reference: 'IDr' is mentioned on line 144, but not defined ** Obsolete normative reference: RFC 5996 (Obsoleted by RFC 7296) Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 3 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: Standards Track Huawei 6 Expires: November 22, 2012 May 21, 2012 8 An IKEv2 Extension for Supporting ERP 9 draft-nir-ipsecme-erx-04 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 5296bis. 18 NOTE TO RFC EDITOR: Replace 5296bis in the previous paragraph with 19 the RFC number assigned to draft-ietf-hokey-rfc5296bis (now in the 20 RFC Editor queue) 22 Status of this Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on November 22, 2012. 39 Copyright Notice 41 Copyright (c) 2012 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 1. Introduction 56 IKEv2, as specified in section 2.16 of [RFC5996], allows 57 authentication of the initiator using an EAP method. Using EAP 58 significantly increases the count of round-trips required to 59 establish the IPsec SA, and also may require user interaction. This 60 makes it inconvenient to allow a single remote access client to 61 create multiple IPsec tunnels with multiple IPsec gateways that 62 belong to the same domain. 64 The EAP Re-authentication Protocol (ERP), as described in 65 [RFC5296bis], allows an EAP peer to authenticate to multiple 66 authenticators, while performing the full EAP method only once. 67 Subsequent authentications require fewer round-trips and no user 68 interaction. 70 Bringing these two technologies together allows a remote access IPsec 71 client to create multiple tunnels with different gateways that belong 72 to a single domain, as well as using the keys from other contexts of 73 using EAP, such as network access within the same domain, to 74 transparently connect to VPN gateways within this domain. 76 1.1. Conventions Used in This Document 78 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 79 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 80 document are to be interpreted as described in [RFC2119]. 82 2. Usage Scenarios 84 This work is motivated by the following scenarios: 85 o Multiple tunnels for a single remote access VPN client. Suppose a 86 company has offices in New York City, Paris, and Shanghai. For 87 historical reasons, the email server is located in the Paris 88 office, while most of the servers hosting the company's intranet 89 are located in Shanghai, and the finance department servers are in 90 NYC. An employee using remote access VPN may need to connect to 91 servers from all three locations. While it is possible to connect 92 to a single gateway, and have that gateway route the requests to 93 the other gateways (perhaps through site to site VPN), this is not 94 efficient, and it is more desirable to have the client initiate 95 three different tunnels. It is, however, not desirable to have 96 the user type in a password three times. 97 o Roaming. In these days of mobile phones and tablets, users often 98 move from the wireless LAN in their office, where access may be 99 granted through 802.1x, to a cellular network where VPN is 100 necessary and back again. Both the VPN server and the 802.1x 101 access point are authenticators that connect to the same AAA 102 servers. So it makes sense to make the transition smooth, without 103 requiring user interaction. The device still needs to detect 104 whether it is within the protected network, in which case it 105 should not use VPN, but this process is beyond the scope of this 106 document. [SecureBeacon] is a now-abandoned attempt at this. 108 3. Protocol Outline 110 Supporting ERX requires an EAP payload in the first IKE_AUTH request. 111 This is a deviation from the rules in RFC 5996, so support needs to 112 be indicated through a Notify payload in the IKE_SA_INIT response. 113 This Notify replaces the EAP-Initiate/Re-auth-Start message of ERX, 114 and therefore contains the domain name, as specified in section 115 5.3.1.1 of [RFC5296bis]. 117 A supporting initiator that has unexpired keys for this domain will 118 send the EAP_Initiate/Re-auth message in an EAP payload in the first 119 IKE_AUTH request. 121 The responder sends the EAP payload content to a backend AAA server, 122 and receives the rMSK and an EAP-Finish/Re-auth message. It then 123 forwards the EAP-Finish/Re-auth message to the Initiator in an EAP 124 payload within the first IKE_AUTH response. 126 The initiator then sends an additional IKE_AUTH request, that 127 includes the AUTH payload which has been calculated using the rMSK in 128 the role of the MSK as described in sections 2.15 and 2.16 of 129 [RFC5996]. The responder replies similarly, and the IKE_AUTH 130 exchange is finished. 132 The following figure is adapted from appendixes C.1 and C.3 of RFC 133 5996, with most of the optional payloads removed. Note that the 134 EAP_Initiate/Re-auth message is added. 136 init request --> SA, KE, Ni, 138 init response <-- SA, KE, Nr, 139 N[ERX_SUPPORTED] 141 first request --> EAP(EAP_Initiate/Re-auth), 142 [[N(HTTP_CERT_LOOKUP_SUPPORTED)], CERTREQ+], 143 IDi, 144 [IDr], 145 [CP(CFG_REQUEST)], 146 SA, TSi, TSr, 147 [V+][N+] 149 first response <-- IDr, [CERT+], AUTH, 150 EAP(EAP-Finish/Re-auth), 151 [V+][N+] 153 last request --> AUTH 155 last response <-- AUTH, 156 [CP(CFG_REPLY)], 157 SA, TSi, TSr, 158 [V+][N+] 160 The IDi payload MUST have ID Type ID_RFC822_ADDR and the data field 161 MUST contain the same value as the KeyName-NAI TLV in the 162 EAP_Initiate/Re-auth message. See Section 3.2 for details. 164 3.1. Clarification About EAP Codes 166 Section 3.16 of RFC 5996 enumerates the EAP codes in EAP messages 167 which are carried in EAP payloads. The enumeration goes only to 4. 168 It is not clear whether that list is supposed to be exhaustive or 169 not. 171 To clarify, an implementation supporting this specification MUST 172 accept and transmit EAP messages with at least the codes for Initiate 173 and Finish (5 and 6), in addition to the four codes enumerated in RFC 174 5996. This document is intentionally silent about other EAP codes 175 that are not enumerated in RFC 5996 or in this document. 177 3.2. User Name in the Protocol 179 The authors, as well as participants of the HOKEY and IPsecME working 180 groups believe that all use cases for this extension to IKE have a 181 single backend AAA server doing both the authentication and the re- 182 authentication. The reasoning behind this is that IKE runs over the 183 Internet, and would naturally connect to the user's home network. 185 This section addresses instances where this is not the case. 187 Section 5.3.2 of [RFC5296bis] describes the EAP-Initiate/Re-auth 188 packet, which in the case of IKEv2 is carried in the first IKE_AUTH 189 request. This packet contains the KeyName-NAI TLV. This TLV 190 contains the username used in authentication. It is relayed to the 191 AAA server in the AccessRequest message, and is returned from the AAA 192 server in the AccessAccept message. 194 The username part of the NAI within the TLV is the EMSKName encoded 195 in hexadecimal digits. The domain part is the domain name of the 196 home domain of the user. The username part is ephemeral in the sense 197 that a new one is generated for each full authentication. This 198 ephemeral value is not a good basis for making policy decisions, and 199 they are also a poor source of user identification for the purposes 200 of logging. 202 Instead, it is up to the implementation in the IPsec gateway to make 203 policy decisions based on other factors. The following list is by no 204 means exhaustive: 205 o In some cases the home domain name may be enough to make policy 206 decisions. If all users with a particular home domain get the 207 same authorization, then policy does not depend on the real user 208 name. Meaningful logs can still be issued by correlating VPN 209 gateway IKE events with AAA servers access records. 210 o Sometimes users receive different authorizations based on groups 211 they belong to. The AAA server can communicate such information 212 to the VPN gateway, for example using the CLASS attribute in 213 RADIUS and Diameter. Logging again depends on correlation with 214 AAA servers. 215 o AAA servers may support extensions that allow them to communicate 216 with their clients (in our case - the VPN gateway) to push user 217 information. For example, a certain product integrates a RADIUS 218 server with LDAP, so a client could query the server using LDAP 219 and receive the real record for this user. Others may provide 220 this data through vendor-specific extensions to RADIUS or 221 DIAMETER. 223 In any case authorization is a major issue in deployments, if the 224 backend AAA server supporting the re-authentication is different from 225 the AAA server that had supported the original authentication. It is 226 up to the re-authenticating AAA server to provide the necessary 227 information for authorization. A conforming implementation of this 228 protocol MAY reject initiators for which it is unable to make policy 229 decisions because of these reasons. 231 4. ERX_SUPPORTED Notification 233 The Notify payload is as described in RFC 5996: 235 1 2 3 236 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 1 237 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 238 ! Next Payload !C! RESERVED ! Payload Length ! 239 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 240 ! Protocol ID ! SPI Size ! ERX Notify Message Type ! 241 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 242 ! Domain Name ! 243 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 245 o Protocol ID (1 octet) MUST be 1, as this message is related to an 246 IKE SA. 247 o SPI Size (1 octet) MUST be zero, in conformance with section 3.10 248 of [RFC5996]. 249 o ERX Notify Message Type (2 octets) - MUST be xxxxx, the value 250 assigned for ERX. TBA by IANA. 251 o Domain Name (variable) - contains the domain name or realm, as 252 these terms are used in [RFC5296bis], and encoded as UTF-8. 254 5. Security Considerations 256 The protocol extension described in this document extends the 257 authentication from one EAP context, which may or may not be part of 258 IKEv2, to an IKEv2 context. Successful completion of the protocol 259 proves to the authenticator, which in our case is a VPN gateway, that 260 the supplicant, or VPN client, has authenticated in some other EAP 261 context. 263 The protocol supplies the authenticator with the domain name with 264 which the supplicant has authenticated, but does not supply it with a 265 specific identity. Instead, the gateway receives an EMSKName, which 266 is an ephemeral ID. 268 If the domain name is sufficient to make access control decisions, 269 this is enough. If not, then the gateway needs to find out either 270 the real name or authorization information for that particular user. 271 This may be done using the AAA protocol or by some other federation 272 protocol, which is out of scope for this specification. 274 6. IANA Considerations 276 IANA is requested to assign a notify message type from the status 277 types range (16418-40959) of the "IKEv2 Notify Message Types" 278 registry with name "ERX_SUPPORTED". 280 7. Acknowledgements 282 The authors would like to thank Yaron Sheffer for comments and 283 suggested text that have contributed to this document. 285 8. References 287 8.1. Normative References 289 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 290 Requirement Levels", BCP 14, RFC 2119, March 1997. 292 [RFC5296bis] 293 Wu, W., Cao, Z., Zorn, G., Shi, Y., and B. He, "EAP 294 Extensions for EAP Re-authentication Protocol (ERP)", 295 draft-ietf-hokey-rfc5296bis-07 (work in progress), 296 May 2012. 298 [RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, 299 "Internet Key Exchange Protocol: IKEv2", RFC 5996, 300 September 2010. 302 8.2. Informative References 304 [SecureBeacon] 305 Sheffer, Y. and Y. Nir, "Secure Beacon: Securely Detecting 306 a Trusted Network", draft-sheffer-ipsecme-secure-beacon 307 (work in progress), June 2009. 309 Authors' Addresses 311 Yoav Nir 312 Check Point Software Technologies Ltd. 313 5 Hasolelim st. 314 Tel Aviv 67897 315 Israel 317 Email: ynir@checkpoint.com 318 Qin Wu 319 Huawei Technologies Co., Ltd. 320 101 Software Avenue, Yuhua District 321 Nanjing, JiangSu 210012 322 China 324 Email: sunseawq@huawei.com