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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 173, but not defined ** Obsolete normative reference: RFC 4306 (Obsoleted by RFC 5996) ** Obsolete normative reference: RFC 4718 (Obsoleted by RFC 5996) Summary: 3 errors (**), 0 flaws (~~), 3 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: Standards Track H. Tschofenig 5 Expires: September 8, 2010 NSN 6 H. Deng 7 China Mobile 8 R. Singh 9 Cisco 10 March 7, 2010 12 A Childless Initiation of the IKE SA 13 draft-nir-ipsecme-childless-03 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 September 8, 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 This document may contain material from IETF Documents or IETF 60 Contributions published or made publicly available before November 61 10, 2008. The person(s) controlling the copyright in some of this 62 material may not have granted the IETF Trust the right to allow 63 modifications of such material outside the IETF Standards Process. 64 Without obtaining an adequate license from the person(s) controlling 65 the copyright in such materials, this document may not be modified 66 outside the IETF Standards Process, and derivative works of it may 67 not be created outside the IETF Standards Process, except to format 68 it for publication as an RFC or to translate it into languages other 69 than English. 71 1. Introduction 73 IKEv2, as specified in [RFC4306] requires, that the IKE_AUTH exchange 74 try to create a Child SA along with the IKE SA. This requirement is 75 sometimes inconvenient or superfluous, as some implementations need 76 to use IKE for authentication only, while others would like to set up 77 the IKE SA before there is any actual traffic to protect. 79 An IKE SA without any Child SA is not a fruitless endeavor. Even 80 without Child SAs, an IKE SA allows: 81 o Checking the liveness status of the peer via liveness checks. 82 o Quickly setting up Child SAs without public key operations, and 83 without user interaction. 84 o Authentication of the peer. 85 o Detection of NAT boxes between two hosts on the Internet 87 1.1. Conventions Used in This Document 89 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 90 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 91 document are to be interpreted as described in [RFC2119]. 93 2. Usage Scenarios 95 Several scenarios motivated this proposal: 96 o Interactive remote access VPN: the user tells the client to 97 "connect", which may involve interactive authentication. There is 98 still no traffic, but some may come later. Since there is no 99 traffic, it is impossible for the gateway to know what selectors 100 to use (how to narrow down the client's proposal). 101 o Location aware security, as in [SecureBeacon]. The user is 102 roaming between trusted and untrusted networks. While in an 103 untrusted network, all traffic should be encrypted, but on the 104 trusted network, only the IKE SA needs to be maintained. 105 o An IKE SA may be needed between peers even when there is not IPsec 106 traffic. Such IKE peers use liveness checks, and report to the 107 administrator the status of the "VPN links". 108 o IKE may be used on some physically secure links, where 109 authentication is necessary, but traffic protection is not. An 110 example of this in the PON links as described in [3GPP.33.820]. 111 o Childless IKE can be used for [EAP-IKEv2] where we use IKEv2 as a 112 method for user authentication. 113 o A node receiving IPsec traffic with an unrecognized SPI should 114 send an INVALID_SPI notification. If this traffic comes from a 115 peer, which it recognizes based on its IP address, then this node 116 may set up an IKE SA so as to be able to send the notification in 117 a protected IKE_INFORMATIONAL exchange. 118 o A future extension may have IKE SAs used for generating keying 119 material for applications, without ever requiring Child SAs. This 120 is similar to what [extractors] is doing in TLS. 122 In some of these cases it may be possible to create a dummy Child SA 123 and then remove it, but this creates undesirable side effects and 124 race conditions. Moreover, the IKE peer might see the deletion of 125 the Child SA as a reason to delete the IKE SA. 127 3. Protocol Outline 129 The decision of whether or not to support an IKE_AUTH exchage without 130 the piggy-backed Child SA negotiation is ultimately up to the 131 reponsder. A supporting resonder MUST include the VID payload, 132 described in Section 4, within the IKE_SA_INIT response. 134 A supporting initiator MAY send the modified IKE_AUTH request, 135 described in Section 5, if the VID payload was included in the 136 IKE_SA_INIT response. The initiator MUST NOT send the modified 137 IKE_AUTH request if the VID was not present. 139 A supporting responder that advertised the VID payload in the 140 IKE_SA_INIT response MUST process a modified IKE_AUTH request, and 141 MUST reply with a modified IKE_AUTH response. Such a responder MUST 142 NOT reply with a modified IKE_AUTH response if the initiator did not 143 send a modified IKE_AUTH request. 145 A supporting responder that has been configured not to support this 146 extension to the protocol MUST behave as the same as if it didn't 147 support this extension. It MUST NOT advertise the capability with a 148 VID payload, and it SHOULD reply with an INVALID_SYNTAX Notify 149 payload if the client sends an IKE_AUTH request that is modified as 150 described in Section 5. 152 4. VID Payload 154 The VID payload is as described in [RFC4306] with a 16-octets data 155 field as follows: 157 73da4b423dd9f75563b15b9f918650fc 159 This value was obtained by hashing the string "Will do IKE_AUTH 160 without Child SA payloads" using the MD5 algorithms. Note that this 161 is only an explanation, and the actual content of the VID data MUST 162 be the value above. 164 5. Modified IKE_AUTH Exchange 166 For brevity, only the EAP version of an AUTH exchange will be 167 presented here. The non-EAP version is very similar. The figures 168 below are based on appendix A.3 of [RFC4718]. 170 first request --> IDi, 171 [N(INITIAL_CONTACT)], 172 [[N(HTTP_CERT_LOOKUP_SUPPORTED)], CERTREQ+], 173 [IDr], 174 [CP(CFG_REQUEST)], 175 [V+] 177 first response <-- IDr, [CERT+], AUTH, 178 EAP, 179 [V+] 181 / --> EAP 182 repeat 1..N times | 183 \ <-- EAP 185 last request --> AUTH 187 last response <-- AUTH, 188 [CP(CFG_REPLY)], 189 [N(ADDITIONAL_TS_POSSIBLE)], 190 [V+] 192 Note what is missing: 193 o The optional notifications: IPCOMP_SUPPORTED, USE_TRANSPORT_MODE, 194 ESP_TFC_PADDING_NOT_SUPPORTED, and NON_FIRST_FRAGMENTS_ALSO. 195 o The SA payload. 196 o The traffic selector payloads. 197 o Any notification, extension payload or VendorID that has to do 198 with Child SA negotiation. 200 6. Security Considerations 202 This protocol variation inherits all the security properties of 203 regular IKEv2 as described in [RFC4306]. 205 The new Vendor ID carried in the initial exchange advertises the 206 capability, and cannot be forged or added by an adversary without 207 being detected, because the response to the initial exchange is 208 authenticated with the AUTH payload of the IKE_AUTH exchange. 209 Furthermore, both peers have to be configured to use this variation 210 of the exchange in order for the responder to accept a childless 211 proposal from the initiator. 213 7. IANA Considerations 215 There are no IANA considerations for this document. 217 8. References 219 8.1. Normative References 221 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 222 Requirement Levels", BCP 14, RFC 2119, March 1997. 224 [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", 225 RFC 4306, December 2005. 227 [RFC4718] Eronen, P. and P. Hoffman, "IKEv2 Clarifications and 228 Implementation Guidelines", RFC 4718, October 2006. 230 8.2. Informative References 232 [3GPP.33.820] 233 3GPP, "Security of H(e)NB", 3GPP TR 33.820 8.0.0, 234 March 2009. 236 [EAP-IKEv2] 237 Tschofenig, H., Kroeselberg, D., Pashalidis, A., Ohba, Y., 238 and F. Bersani, "The Extensible Authentication Protocol- 239 Internet Key Exchange Protocol version 2 (EAP-IKEv2) 240 Method", RFC 5106, February 2008. 242 [SecureBeacon] 243 Sheffer, Y. and Y. Nir, "Secure Beacon: Securely Detecting 244 a Trusted Network", draft-sheffer-ipsecme-secure-beacon 245 (work in progress), June 2009. 247 [extractors] 248 Rescorla, E., "Keying Material Exporters for Transport 249 Layer Security (TLS)", draft-ietf-tls-extractor (work in 250 progress), March 2009. 252 Authors' Addresses 254 Yoav Nir 255 Check Point Software Technologies Ltd. 256 5 Hasolelim st. 257 Tel Aviv 67897 258 Israel 260 Email: ynir@checkpoint.com 261 Hannes Tschofenig 262 Nokia Siemens Networks 263 Linnoitustie 6 264 Espoo 02600 265 Finland 267 Phone: +358 (50) 4871445 268 Email: Hannes.Tschofenig@gmx.net 269 URI: http://www.tschofenig.priv.at 271 Hui Deng 272 China Mobile 273 53A,Xibianmennei Ave. 274 Xuanwu District 275 Beijing 100053 276 China 278 Email: denghui02@gmail.com 280 Rajeshwar Singh Jenwar 281 Cisco Systems, Inc. 282 O'Shaugnessy Road 283 Bangalore, Karnataka 560025 284 India 286 Phone: +91 80 4103 3563 287 Email: rsj@cisco.com