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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: December 19, 2009 NSN 6 H. Deng 7 China Mobile 8 June 17, 2009 10 A Childless Initiation of the IKE SA 11 draft-nir-ike-nochild-02 13 Status of this Memo 15 This Internet-Draft is submitted to IETF in full conformance with the 16 provisions of BCP 78 and BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on December 19, 2009. 36 Copyright Notice 38 Copyright (c) 2009 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents in effect on the date of 43 publication of this document (http://trustee.ietf.org/license-info). 44 Please review these documents carefully, as they describe your rights 45 and restrictions with respect to this document. 47 Abstract 49 This document describes an extension to the IKEv2 protocol that 50 allows an IKE SA to be created and authenticated without generating a 51 child SA. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 56 1.1. Conventions Used in This Document . . . . . . . . . . . . . 3 57 2. Usage Scenarios . . . . . . . . . . . . . . . . . . . . . . . . 3 58 3. Protocol Outline . . . . . . . . . . . . . . . . . . . . . . . 4 59 4. VID Payload . . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 5. Modified IKE_AUTH Exchange . . . . . . . . . . . . . . . . . . 5 61 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 62 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 63 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 64 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 65 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 68 1. Introduction 70 IKEv2, as specified in [RFC4306] requires that in an IKE_AUTH 71 exchange, a child SA is created along with the IKE SA. This 72 requirement is sometimes inconvenient, as some implementations need 73 to use IKE for authentication only, while other implementations would 74 like to set up the IKE SA before there is any actual traffic to 75 protect. 77 An IKE SA without any child SA is not a fruitless endeavor. Even 78 without Child SAs, an IKE SA allows: 79 o Checking the liveness status of the peer via liveness checks. 80 o Quickly setting up child SAs without public key operations, and/or 81 without user interaction. 82 o Authentication of the peer. 84 1.1. Conventions Used in This Document 86 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 87 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 88 document are to be interpreted as described in [RFC2119]. 90 2. Usage Scenarios 92 Several scenarios motivated this proposal: 93 o Interactive remote access VPN: the user tells the client to 94 "connect", which may involve interactive authentication. There is 95 still no traffic, but some may come later. Since there is no 96 traffic, it is impossible for the gateway to know what selectors 97 to use (how to narrow down the client's proposal). 98 o Location aware security, as in [SecureBeacon]. The user is 99 roaming between trusted and untrusted networks. While in an 100 untrusted network, all traffic should be encrypted, but on the 101 trusted network, only the IKE SA needs to be maintained. 102 o An IKE SA may be needed between peers even when there is not IPsec 103 traffic. Such IKE peers use liveness checks, and report to the 104 administrator the status of the "VPN links". 105 o IKE may be used on some physically secure links, where 106 authentication is necessary, but traffic protection is not. An 107 example of this in the PON links as described in [3GPP.33.820]. 108 o A node receiving IPsec traffic with an unrecognized SPI should 109 send an INVALID_SPI notification. If this traffic comes from a 110 peer, which it recognizes based on its IP address, then this node 111 may set up an IKE SA so as to be able to send the notification in 112 a protected IKE_INFORMATIONAL exchange. 114 o A future extension may have IKE SAs used for generating keying 115 material for applications, without ever requiring child SAs. This 116 is similar to what [extractors] is doing in TLS. 118 In some of these cases it may be possible to create a dummy Child SA 119 and then remove it, but this creates undesirable side effects and 120 race conditions. Moreover, the IKE peer might see the deletion of 121 the Child SA as a reason to delete the IKE SA. 123 3. Protocol Outline 125 The decision of whether or not to support an IKE_AUTH exchage without 126 the piggy-backed child SA negotiation is ultimately up to the 127 reponsder. A supporting resonder MUST include the VID payload, 128 described in Section 4, within the IKE_INIT response. 130 A supporting initiator MAY send the modified IKE_AUTH request, 131 described in Section 5, if the VID payload was included in the 132 IKE_INIT response. The initiator MUST NOT send the modified IKE_AUTH 133 request if the VID was not present. 135 A supporting responder that advertised the VID payload in the 136 IKE_INIT response MUST process a modified IKE_AUTH request, and MUST 137 reply with a modified IKE_AUTH response. Such a responder MUST NOT 138 reply with a modified IKE_AUTH response if the initiator did not send 139 a modified IKE_AUTH request. 141 A supporting responder that has been configured not to support this 142 extension to the protocol MUST behave as the same as if it didn't 143 support this extension. It MUST NOT advertise the capability with a 144 VID payload, and it SHOULD reply with an INVALID_SYNTAX Notify 145 payload if the client sends an IKE_AUTH request that is modified as 146 described in Section 5. 148 4. VID Payload 150 The VID payload is as described in [RFC4306] with the data as 151 follows: 153 73da4b423dd9f75563b15b9f918650fc 155 This value was obtained by hashing the string "Will do IKE_AUTH 156 without child SA payloads" 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 A.3 of [RFC4718]. 164 first request --> IDi, 165 [N(INITIAL_CONTACT)], 166 [[N(HTTP_CERT_LOOKUP_SUPPORTED)], CERTREQ+], 167 [IDr], 168 [CP(CFG_REQUEST)], 169 [V+] 171 first response <-- IDr, [CERT+], AUTH, 172 EAP, 173 [V+] 175 / --> EAP 176 repeat 1..N times | 177 \ <-- EAP 179 last request --> AUTH 181 last response <-- AUTH, 182 [CP(CFG_REPLY)], 183 [V+] 185 Note what is missing: 186 o The optional notifications: IPCOMP_SUPPORTED, USE_TRANSPORT_MODE, 187 ESP_TFC_PADDING_NOT_SUPPORTED, and NON_FIRST_FRAGMENTS_ALSO. 188 o The SA payload. 189 o The traffic selector payloads. 190 o Any notification, extension payload or VendorID that has to do 191 with child SA negotiation. 193 6. Security Considerations 195 TBA 197 7. IANA Considerations 199 There are no IANA considerations for this document. 201 8. References 202 8.1. Normative References 204 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 205 Requirement Levels", BCP 14, RFC 2119, March 1997. 207 [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", 208 RFC 4306, December 2005. 210 [RFC4718] Eronen, P. and P. Hoffman, "IKEv2 Clarifications and 211 Implementation Guidelines", RFC 4718, October 2006. 213 8.2. Informative References 215 [3GPP.33.820] 216 3GPP, "Security of H(e)NB", 3GPP TR 33.820 8.0.0, 217 March 2009. 219 [SecureBeacon] 220 Sheffer, Y. and Y. Nir, "Secure Beacon: Securely Detecting 221 a Trusted Network", draft-sheffer-ipsec-secure-beacon 222 (work in progress), January 2008. 224 [extractors] 225 Rescorla, E., "Keying Material Exporters for Transport 226 Layer Security (TLS)", draft-ietf-tls-extractor (work in 227 progress), March 2009. 229 Authors' Addresses 231 Yoav Nir 232 Check Point Software Technologies Ltd. 233 5 Hasolelim st. 234 Tel Aviv 67897 235 Israel 237 Email: ynir@checkpoint.com 238 Hannes Tschofenig 239 Nokia Siemens Networks 240 Linnoitustie 6 241 Espoo 02600 242 Finland 244 Phone: +358 (50) 4871445 245 Email: Hannes.Tschofenig@gmx.net 246 URI: http://www.tschofenig.priv.at 248 Hui Deng 249 China Mobile 250 53A,Xibianmennei Ave. 251 Xuanwu District 252 Beijing 100053 253 China 255 Email: denghui02@gmail.com