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Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Missing Reference: 'IDr' is mentioned on line 164, but not defined ** Obsolete normative reference: RFC 4306 (Obsoleted by RFC 5996) ** Obsolete normative reference: RFC 4718 (Obsoleted by RFC 5996) Summary: 2 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: January 1, 2011 NSN 6 H. Deng 7 China Mobile 8 R. Singh 9 Cisco 10 June 30, 2010 12 A Childless Initiation of the IKE SA 13 draft-nir-ipsecme-childless-04 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 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 January 1, 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 [RFC4306], requires that the IKE_AUTH exchange 56 try to create a Child SA along with the IKE SA. This requirement is 57 sometimes inconvenient or superfluous, as some implementations need 58 to use IKE for authentication only, while others would like to set up 59 the IKE SA before there is any actual traffic to protect. The 60 extension described in this document allows the creation of an IKE SA 61 without also attempting to create a Child SA. 63 An IKE SA without any Child SA is not a fruitless endeavor. Even 64 without Child SAs, an IKE SA allows: 65 o Checking the liveness status of the peer via liveness checks. 66 o Quickly setting up Child SAs without public key operations, and 67 without user interaction. 68 o Authentication of the peer. 69 o Detection of NAT boxes between two hosts on the Internet 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 Several scenarios motivated this proposal: 80 o Interactive remote access VPN: the user tells the client to 81 "connect", which may involve interactive authentication. There is 82 still no traffic, but some may come later. Since there is no 83 traffic, it is impossible for the gateway to know what selectors 84 to use (how to narrow down the client's proposal). 85 o Location aware security, as in [SecureBeacon]. The user is 86 roaming between trusted and untrusted networks. While in an 87 untrusted network, all traffic should be encrypted, but on the 88 trusted network, only the IKE SA needs to be maintained. 89 o An IKE SA may be needed between peers even when there is not IPsec 90 traffic. Such IKE peers use liveness checks, and report to the 91 administrator the status of the "VPN links". 92 o IKE may be used on some physically secure links, where 93 authentication is necessary, but traffic protection is not. An 94 example of this in the PON links as described in [3GPP.33.820]. 96 o Childless IKE can be used for [EAP-IKEv2] where we use IKEv2 as a 97 method for user authentication. 98 o A node receiving IPsec traffic with an unrecognized SPI should 99 send an INVALID_SPI notification. If this traffic comes from a 100 peer, which it recognizes based on its IP address, then this node 101 may set up an IKE SA so as to be able to send the notification in 102 a protected IKE_INFORMATIONAL exchange. 103 o A future extension may have IKE SAs used for generating keying 104 material for applications, without ever requiring Child SAs. This 105 is similar to what [extractors] is doing in TLS. 107 In some of these cases it may be possible to create a dummy Child SA 108 and then remove it, but this creates undesirable side effects and 109 race conditions. Moreover, the IKE peer might see the deletion of 110 the Child SA as a reason to delete the IKE SA. 112 3. Protocol Outline 114 The decision of whether or not to support an IKE_AUTH exchange 115 without the piggy-backed Child SA negotiation is ultimately up to the 116 responder. A supporting responder MUST include the Notify payload, 117 described in Section 4, within the IKE_SA_INIT response. 119 A supporting initiator MAY send the modified IKE_AUTH request, 120 described in Section 5, if the Notification was included in the 121 IKE_SA_INIT response. The initiator MUST NOT send the modified 122 IKE_AUTH request if the Notification was not present. 124 A supporting responder that has advertised support by including the 125 notification in the IKE_SA_INIT response MUST process a modified 126 IKE_AUTH request, and MUST reply with a modified IKE_AUTH response. 127 Such a responder MUST NOT reply with a modified IKE_AUTH response if 128 the initiator did not send a modified IKE_AUTH request. 130 A supporting responder that has been configured not to support this 131 extension to the protocol MUST behave as the same as if it didn't 132 support this extension. It MUST NOT advertise the capability with a 133 notification, and it SHOULD reply with an INVALID_SYNTAX Notify 134 payload if the client sends an IKE_AUTH request that is modified as 135 described in Section 5. 137 4. CHILDLESS_IKE_SUPPORTED Notification 139 The Notify payload is as described in [RFC4306] 140 1 2 3 141 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 1 142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 143 ! Next Payload !C! RESERVED ! Payload Length ! 144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 145 ! Protocol ID ! SPI Size ! Childless Notify Message Type ! 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 148 o Protocol ID (1 octet) MUST be 1, as this message is related to an 149 IKE SA. 150 o SPI Size (1 octet) MUST be zero, in conformance with section 3.10 151 of [RFC4306]. 152 o Childless Notify Message Type (2 octets) - MUST be xxxxx, the 153 value assigned for CHILDLESS_IKE_SUPPORTED. TBA by IANA. 155 5. Modified IKE_AUTH Exchange 157 For brevity, only the EAP version of an AUTH exchange will be 158 presented here. The non-EAP version is very similar. The figures 159 below are based on appendix A.3 of [RFC4718]. 161 first request --> IDi, 162 [N(INITIAL_CONTACT)], 163 [[N(HTTP_CERT_LOOKUP_SUPPORTED)], CERTREQ+], 164 [IDr], 165 [CP(CFG_REQUEST)], 166 [V+] 168 first response <-- IDr, [CERT+], AUTH, 169 EAP, 170 [V+] 172 / --> EAP 173 repeat 1..N times | 174 \ <-- EAP 176 last request --> AUTH 178 last response <-- AUTH, 179 [CP(CFG_REPLY)], 180 [N(ADDITIONAL_TS_POSSIBLE)], 181 [V+] 183 Note what is missing: 184 o The optional notifications: IPCOMP_SUPPORTED, USE_TRANSPORT_MODE, 185 ESP_TFC_PADDING_NOT_SUPPORTED, and NON_FIRST_FRAGMENTS_ALSO. 187 o The SA payload. 188 o The traffic selector payloads. 189 o Any notification, extension payload or VendorID that has to do 190 with Child SA negotiation. 192 6. Security Considerations 194 This protocol variation inherits all the security properties of 195 regular IKEv2 as described in [RFC4306]. 197 The new notification carried in the initial exchange advertises the 198 capability, and cannot be forged or added by an adversary without 199 being detected, because the response to the initial exchange is 200 authenticated with the AUTH payload of the IKE_AUTH exchange. 201 Furthermore, both peers have to be configured to use this variation 202 of the exchange in order for the responder to accept a childless 203 proposal from the initiator. 205 7. IANA Considerations 207 IANA is requested to assign a notify message type from the status 208 types range (16418-40959) of the "IKEv2 Notify Message Types" 209 registry with name "CHILDLESS_IKE_SUPPORTED". 211 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 256 Hannes Tschofenig 257 Nokia Siemens Networks 258 Linnoitustie 6 259 Espoo 02600 260 Finland 262 Phone: +358 (50) 4871445 263 Email: Hannes.Tschofenig@gmx.net 264 URI: http://www.tschofenig.priv.at 266 Hui Deng 267 China Mobile 268 53A,Xibianmennei Ave. 269 Xuanwu District 270 Beijing 100053 271 China 273 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