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Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Missing Reference: 'IDr' is mentioned on line 167, but not defined Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). 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: Experimental H. Tschofenig 5 Expires: February 13, 2011 NSN 6 H. Deng 7 China Mobile 8 R. Singh 9 Cisco 10 August 12, 2010 12 A Childless Initiation of the IKE SA 13 draft-nir-ipsecme-childless-06 15 Abstract 17 This document describes an extension to the IKEv2 protocol that 18 allows an IKE Security Association (SA) to be created and 19 authenticated without generating a Child SA. 21 Status of this Memo 23 This Internet-Draft is submitted 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 February 13, 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 1. Introduction 55 IKEv2, as specified in [IKEv2bis], requires that the IKE_AUTH 56 exchange try to create a Child SA along with the IKE SA. This 57 requirement is sometimes inconvenient or superfluous, as some 58 implementations need to use IKE for authentication only, while others 59 would like to set up the IKE SA before there is any actual traffic to 60 protect. The extension described in this document allows the 61 creation of an IKE SA without also attempting to create a Child SA. 62 The terms IKE, IKE SA, Child SA and the various IKE exchanges are 63 defined in [IKEv2bis] 65 An IKE SA without any Child SA is not a fruitless endeavor. Even 66 without Child SAs, an IKE SA allows: 67 o Checking the liveness status of the peer via liveness checks. 68 o Quickly setting up Child SAs without public key operations, and 69 without user interaction. 70 o Authentication of the peer. 71 o Detection of NAT boxes between two hosts on the Internet 73 1.1. Conventions Used in This Document 75 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 76 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 77 document are to be interpreted as described in [RFC2119]. 79 2. Usage Scenarios 81 Several scenarios motivated this proposal: 82 o Interactive remote access VPN: the user tells the client to 83 "connect", which may involve interactive authentication. There is 84 still no traffic, but some may come later. Since there is no 85 traffic, it is impossible for the gateway to know what selectors 86 to use (how to narrow down the client's proposal). 87 o Location aware security, as in [SecureBeacon]. The user is 88 roaming between trusted and untrusted networks. While in an 89 untrusted network, all traffic should be encrypted, but on the 90 trusted network, only the IKE SA needs to be maintained. 91 o An IKE SA may be needed between peers even when there is not IPsec 92 traffic. Such IKE peers use liveness checks, and report to the 93 administrator the status of the "VPN links". 95 o IKE may be used on some physically secure links, where 96 authentication is necessary, but traffic protection is not. An 97 example of this is the PON links as described in [3GPP.33.820]. 98 o Childless IKE can be used for [EAP-IKEv2] where we use IKEv2 as a 99 method for user authentication. 100 o A node receiving IPsec traffic with an unrecognized SPI should 101 send an INVALID_SPI notification. If this traffic comes from a 102 peer, which it recognizes based on its IP address, then this node 103 may set up an IKE SA so as to be able to send the notification in 104 a protected IKE_INFORMATIONAL exchange. 105 o A future extension may have IKE SAs used for generating keying 106 material for applications, without ever requiring Child SAs. This 107 is similar to what [extractors] is doing in TLS. 109 In some of these cases it may be possible to create a dummy Child SA 110 and then remove it, but this creates undesirable side effects and 111 race conditions. Moreover, the IKE peer might see the deletion of 112 the Child SA as a reason to delete the IKE SA. 114 3. Protocol Outline 116 The decision of whether or not to support an IKE_AUTH exchange 117 without the piggy-backed Child SA negotiation is ultimately up to the 118 responder. A supporting responder MUST include the Notify payload, 119 described in Section 4, within the IKE_SA_INIT response. 121 A supporting initiator MAY send the modified IKE_AUTH request, 122 described in Section 5, if the Notification was included in the 123 IKE_SA_INIT response. The initiator MUST NOT send the modified 124 IKE_AUTH request if the Notification was not present. 126 A supporting responder that has advertised support by including the 127 notification in the IKE_SA_INIT response MUST process a modified 128 IKE_AUTH request, and MUST reply with a modified IKE_AUTH response. 129 Such a responder MUST NOT reply with a modified IKE_AUTH response if 130 the initiator did not send a modified IKE_AUTH request. 132 A supporting responder that has been configured not to support this 133 extension to the protocol MUST behave as the same as if it didn't 134 support this extension. It MUST NOT advertise the capability with a 135 notification, and it SHOULD reply with an INVALID_SYNTAX Notify 136 payload if the client sends an IKE_AUTH request that is modified as 137 described in Section 5. 139 4. CHILDLESS_IKE_SUPPORTED Notification 141 The Notify payload is as described in [IKEv2bis] 143 1 2 3 144 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 1 145 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 146 ! Next Payload !C! RESERVED ! Payload Length ! 147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 148 ! Protocol ID ! SPI Size ! Childless Notify Message Type ! 149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 151 o Protocol ID (1 octet) MUST be 1, as this message is related to an 152 IKE SA. 153 o SPI Size (1 octet) MUST be zero, in conformance with section 3.10 154 of [IKEv2bis]. 155 o Childless Notify Message Type (2 octets) - MUST be xxxxx, the 156 value assigned for CHILDLESS_IKE_SUPPORTED. TBA by IANA. 158 5. Modified IKE_AUTH Exchange 160 For brevity, only the EAP version of an AUTH exchange will be 161 presented here. The non-EAP version is very similar. The figures 162 below are based on appendix C.3 of [IKEv2bis]. 164 first request --> IDi, 165 [N(INITIAL_CONTACT)], 166 [[N(HTTP_CERT_LOOKUP_SUPPORTED)], CERTREQ+], 167 [IDr], 168 [CP(CFG_REQUEST)], 169 [V+][N+] 171 first response <-- IDr, [CERT+], AUTH, 172 EAP, 173 [V+][N+] 175 / --> EAP 176 repeat 1..N times | 177 \ <-- EAP 179 last request --> AUTH 181 last response <-- AUTH, 182 [CP(CFG_REPLY)], 183 [V+][N+] 185 Note what is missing: 187 o The optional notifications: IPCOMP_SUPPORTED, USE_TRANSPORT_MODE, 188 ESP_TFC_PADDING_NOT_SUPPORTED, and NON_FIRST_FRAGMENTS_ALSO. 189 o The SA payload. 190 o The traffic selector payloads. 191 o Any notification, extension payload or VendorID that has to do 192 with Child SA negotiation. 194 6. Security Considerations 196 This protocol variation inherits all the security properties of 197 regular IKEv2 as described in [IKEv2bis]. 199 The new notification carried in the initial exchange advertises the 200 capability, and cannot be forged or added by an adversary without 201 being detected, because the response to the initial exchange is 202 authenticated with the AUTH payload of the IKE_AUTH exchange. 203 Furthermore, both peers have to be configured to use this variation 204 of the exchange in order for the responder to accept a childless 205 proposal from the initiator. 207 7. IANA Considerations 209 IANA is requested to assign a notify message type from the status 210 types range (16418-40959) of the "IKEv2 Notify Message Types" 211 registry with name "CHILDLESS_IKE_SUPPORTED". 213 8. References 215 8.1. Normative References 217 [IKEv2bis] 218 Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, 219 "Internet Key Exchange Protocol: IKEv2", 220 draft-ietf-ipsecme-ikev2bis-11 (work in progress), 221 May 2010. 223 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 224 Requirement Levels", BCP 14, RFC 2119, March 1997. 226 8.2. Informative References 228 [3GPP.33.820] 229 3GPP, "Security of H(e)NB", 3GPP TR 33.820 8.0.0, 230 March 2009. 232 [EAP-IKEv2] 233 Tschofenig, H., Kroeselberg, D., Pashalidis, A., Ohba, Y., 234 and F. Bersani, "The Extensible Authentication Protocol- 235 Internet Key Exchange Protocol version 2 (EAP-IKEv2) 236 Method", RFC 5106, February 2008. 238 [SecureBeacon] 239 Sheffer, Y. and Y. Nir, "Secure Beacon: Securely Detecting 240 a Trusted Network", draft-sheffer-ipsecme-secure-beacon 241 (work in progress), June 2009. 243 [extractors] 244 Rescorla, E., "Keying Material Exporters for Transport 245 Layer Security (TLS)", draft-ietf-tls-extractor (work in 246 progress), March 2009. 248 Authors' Addresses 250 Yoav Nir 251 Check Point Software Technologies Ltd. 252 5 Hasolelim st. 253 Tel Aviv 67897 254 Israel 256 Email: ynir@checkpoint.com 258 Hannes Tschofenig 259 Nokia Siemens Networks 260 Linnoitustie 6 261 Espoo 02600 262 Finland 264 Phone: +358 (50) 4871445 265 Email: Hannes.Tschofenig@gmx.net 266 URI: http://www.tschofenig.priv.at 268 Hui Deng 269 China Mobile 270 53A,Xibianmennei Ave. 271 Xuanwu District 272 Beijing 100053 273 China 275 Email: denghui02@gmail.com 276 Rajeshwar Singh Jenwar 277 Cisco Systems, Inc. 278 O'Shaugnessy Road 279 Bangalore, Karnataka 560025 280 India 282 Phone: +91 80 4103 3563 283 Email: rsj@cisco.com