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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 Intended status: Standards Track H. Tschofenig 5 Expires: August 4, 2010 NSN 6 H. Deng 7 China Mobile 8 R. Singh 9 Cisco 10 January 31, 2010 12 A Childless Initiation of the IKE SA 13 draft-nir-ipsecme-childless-02 15 Abstract 17 This document describes an extension to the IKEv2 protocol that 18 allows an IKE SA to be created and authenticated without generating a 19 child SA. 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), its areas, and its working groups. Note that 28 other groups may also distribute working documents as Internet- 29 Drafts. 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 The list of current Internet-Drafts can be accessed at 37 http://www.ietf.org/ietf/1id-abstracts.txt. 39 The list of Internet-Draft Shadow Directories can be accessed at 40 http://www.ietf.org/shadow.html. 42 This Internet-Draft will expire on August 4, 2010. 44 Copyright Notice 46 Copyright (c) 2010 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (http://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 62 1.1. Conventions Used in This Document . . . . . . . . . . . . . 3 63 2. Usage Scenarios . . . . . . . . . . . . . . . . . . . . . . . . 3 64 3. Protocol Outline . . . . . . . . . . . . . . . . . . . . . . . 4 65 4. VID Payload . . . . . . . . . . . . . . . . . . . . . . . . . . 4 66 5. Modified IKE_AUTH Exchange . . . . . . . . . . . . . . . . . . 5 67 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 68 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 69 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 70 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 71 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 74 1. Introduction 76 IKEv2, as specified in [RFC4306] requires, that the IKE_AUTH exchange 77 try to create a child SA along with the IKE SA. This requirement is 78 sometimes inconvenient or superfluous, as some implementations need 79 to use IKE for authentication only, while others would like to set up 80 the IKE SA before there is any actual traffic to protect. 82 An IKE SA without any child SA is not a fruitless endeavor. Even 83 without Child SAs, an IKE SA allows: 84 o Checking the liveness status of the peer via liveness checks. 85 o Quickly setting up child SAs without public key operations, and 86 without user interaction. 87 o Authentication of the peer. 88 o Detection of NAT boxes between two hosts on the Internet 90 1.1. Conventions Used in This Document 92 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 93 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 94 document are to be interpreted as described in [RFC2119]. 96 2. Usage Scenarios 98 Several scenarios motivated this proposal: 99 o Interactive remote access VPN: the user tells the client to 100 "connect", which may involve interactive authentication. There is 101 still no traffic, but some may come later. Since there is no 102 traffic, it is impossible for the gateway to know what selectors 103 to use (how to narrow down the client's proposal). 104 o Location aware security, as in [SecureBeacon]. The user is 105 roaming between trusted and untrusted networks. While in an 106 untrusted network, all traffic should be encrypted, but on the 107 trusted network, only the IKE SA needs to be maintained. 108 o An IKE SA may be needed between peers even when there is not IPsec 109 traffic. Such IKE peers use liveness checks, and report to the 110 administrator the status of the "VPN links". 111 o IKE may be used on some physically secure links, where 112 authentication is necessary, but traffic protection is not. An 113 example of this in the PON links as described in [3GPP.33.820]. 114 o Childless IKE can be used for [EAP-IKEv2] where we use IKEv2 as a 115 method for user authentication. 116 o A node receiving IPsec traffic with an unrecognized SPI should 117 send an INVALID_SPI notification. If this traffic comes from a 118 peer, which it recognizes based on its IP address, then this node 119 may set up an IKE SA so as to be able to send the notification in 120 a protected IKE_INFORMATIONAL exchange. 122 o A future extension may have IKE SAs used for generating keying 123 material for applications, without ever requiring child SAs. This 124 is similar to what [extractors] is doing in TLS. 126 In some of these cases it may be possible to create a dummy Child SA 127 and then remove it, but this creates undesirable side effects and 128 race conditions. Moreover, the IKE peer might see the deletion of 129 the Child SA as a reason to delete the IKE SA. 131 3. Protocol Outline 133 The decision of whether or not to support an IKE_AUTH exchage without 134 the piggy-backed child SA negotiation is ultimately up to the 135 reponsder. A supporting resonder MUST include the VID payload, 136 described in Section 4, within the IKE_SA_INIT response. 138 A supporting initiator MAY send the modified IKE_AUTH request, 139 described in Section 5, if the VID payload was included in the 140 IKE_SA_INIT response. The initiator MUST NOT send the modified 141 IKE_AUTH request if the VID was not present. 143 A supporting responder that advertised the VID payload in the 144 IKE_SA_INIT response MUST process a modified IKE_AUTH request, and 145 MUST reply with a modified IKE_AUTH response. Such a responder MUST 146 NOT reply with a modified IKE_AUTH response if the initiator did not 147 send a modified IKE_AUTH request. 149 A supporting responder that has been configured not to support this 150 extension to the protocol MUST behave as the same as if it didn't 151 support this extension. It MUST NOT advertise the capability with a 152 VID payload, and it SHOULD reply with an INVALID_SYNTAX Notify 153 payload if the client sends an IKE_AUTH request that is modified as 154 described in Section 5. 156 4. VID Payload 158 The VID payload is as described in [RFC4306] with a 16-octets data 159 field as follows: 161 73da4b423dd9f75563b15b9f918650fc 163 This value was obtained by hashing the string "Will do IKE_AUTH 164 without child SA payloads" using the MD5 algorithms. Note that this 165 is only an explanation, and the actual content of the VID data MUST 166 be the value above. 168 5. Modified IKE_AUTH Exchange 170 For brevity, only the EAP version of an AUTH exchange will be 171 presented here. The non-EAP version is very similar. The figures 172 below are based on appendix A.3 of [RFC4718]. 174 first request --> IDi, 175 [N(INITIAL_CONTACT)], 176 [[N(HTTP_CERT_LOOKUP_SUPPORTED)], CERTREQ+], 177 [IDr], 178 [CP(CFG_REQUEST)], 179 [V+] 181 first response <-- IDr, [CERT+], AUTH, 182 EAP, 183 [V+] 185 / --> EAP 186 repeat 1..N times | 187 \ <-- EAP 189 last request --> AUTH 191 last response <-- AUTH, 192 [CP(CFG_REPLY)], 193 [N(ADDITIONAL_TS_POSSIBLE)], 194 [V+] 196 Note what is missing: 197 o The optional notifications: IPCOMP_SUPPORTED, USE_TRANSPORT_MODE, 198 ESP_TFC_PADDING_NOT_SUPPORTED, and NON_FIRST_FRAGMENTS_ALSO. 199 o The SA payload. 200 o The traffic selector payloads. 201 o Any notification, extension payload or VendorID that has to do 202 with child SA negotiation. 204 6. Security Considerations 206 TBA 208 7. IANA Considerations 210 There are no IANA considerations for this document. 212 8. References 213 8.1. Normative References 215 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 216 Requirement Levels", BCP 14, RFC 2119, March 1997. 218 [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", 219 RFC 4306, December 2005. 221 [RFC4718] Eronen, P. and P. Hoffman, "IKEv2 Clarifications and 222 Implementation Guidelines", RFC 4718, October 2006. 224 8.2. Informative References 226 [3GPP.33.820] 227 3GPP, "Security of H(e)NB", 3GPP TR 33.820 8.0.0, 228 March 2009. 230 [EAP-IKEv2] 231 Tschofenig, H., Kroeselberg, D., Pashalidis, A., Ohba, Y., 232 and F. Bersani, "The Extensible Authentication Protocol- 233 Internet Key Exchange Protocol version 2 (EAP-IKEv2) 234 Method", RFC 5106, February 2008. 236 [SecureBeacon] 237 Sheffer, Y. and Y. Nir, "Secure Beacon: Securely Detecting 238 a Trusted Network", draft-sheffer-ipsecme-secure-beacon 239 (work in progress), June 2009. 241 [extractors] 242 Rescorla, E., "Keying Material Exporters for Transport 243 Layer Security (TLS)", draft-ietf-tls-extractor (work in 244 progress), March 2009. 246 Authors' Addresses 248 Yoav Nir 249 Check Point Software Technologies Ltd. 250 5 Hasolelim st. 251 Tel Aviv 67897 252 Israel 254 Email: ynir@checkpoint.com 255 Hannes Tschofenig 256 Nokia Siemens Networks 257 Linnoitustie 6 258 Espoo 02600 259 Finland 261 Phone: +358 (50) 4871445 262 Email: Hannes.Tschofenig@gmx.net 263 URI: http://www.tschofenig.priv.at 265 Hui Deng 266 China Mobile 267 53A,Xibianmennei Ave. 268 Xuanwu District 269 Beijing 100053 270 China 272 Email: denghui02@gmail.com 274 Rajeshwar Singh Jenwar 275 Cisco Systems, Inc. 276 O'Shaugnessy Road 277 Bangalore, Karnataka 560025 278 India 280 Phone: +91 80 4103 3563 281 Email: rsj@cisco.com