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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 3315 (Obsoleted by RFC 8415) == Outdated reference: A later version (-07) exists of draft-ietf-dhc-secure-dhcpv6-03 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group D. Evans 3 Internet-Draft ARRIS International, Inc. 4 Intended status: Standards Track R. Droms 5 Updates: 3315 Cisco Systems, Inc. 6 Expires: February 23, 2012 S. Jiang 7 Huawei Technologies Co., Ltd 8 August 22, 2011 10 Rebind Capability in DHCPv6 Reconfigure Messages 11 draft-ietf-dhc-dhcpv6-reconfigure-rebind-08.txt 13 Abstract 15 This document updates RFC 3315 to allow the Rebind message type to 16 appear in the Reconfigure Message option of a Reconfigure message, 17 which extends the Reconfigure message to allow a DHCPv6 server to 18 cause a DHCPv6 client to send a Rebind message. The document also 19 clarifies how a DHCPv6 client responds to a received Reconfigure 20 message. 22 Status of this Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on February 23, 2012. 39 Copyright Notice 41 Copyright (c) 2011 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 This document may contain material from IETF Documents or IETF 55 Contributions published or made publicly available before November 56 10, 2008. The person(s) controlling the copyright in some of this 57 material may not have granted the IETF Trust the right to allow 58 modifications of such material outside the IETF Standards Process. 59 Without obtaining an adequate license from the person(s) controlling 60 the copyright in such materials, this document may not be modified 61 outside the IETF Standards Process, and derivative works of it may 62 not be created outside the IETF Standards Process, except to format 63 it for publication as an RFC or to translate it into languages other 64 than English. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 69 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4 70 3. The Reconfigure Message option of the DHCPv6 Reconfigure 71 Message . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 72 4. Server Behavior . . . . . . . . . . . . . . . . . . . . . . . . 5 73 5. Client Behavior . . . . . . . . . . . . . . . . . . . . . . . . 6 74 6. Clarification of section 19.4.2, RFC 3315 . . . . . . . . . . . 6 75 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 76 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 77 9. Change log [RFC Editor please remove] . . . . . . . . . . . . . 7 78 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 79 10.1. Normative References . . . . . . . . . . . . . . . . . . . 7 80 10.2. Informative References . . . . . . . . . . . . . . . . . . 7 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 83 1. Introduction 85 DHCPv6 [RFC3315] allows a server to send an unsolicited Reconfigure 86 message to a client. The client's response to a Reconfigure message, 87 according to section 19 of RFC 3315 is either a Renew or an 88 Information-Request message, depending on the contents of the msg- 89 type field in the Reconfigure Message option of the Reconfigure 90 message. If the client sends a Renew message, it includes a Server 91 Identifier option in the Renew message to specify the server that 92 should respond to the Renew message. The RFC 3315 specification is 93 only suitable for the scenarios that client would communicate with 94 the same DHCPv6 servers. 96 There are also scenarios that the client may desire to communicate 97 with a different server: for example, a network administrator may 98 initiatively want to shut down a DHCPv6 server and move these clients 99 who most recently communicated with to another different server. 100 Hence, this document expands the allowed values of the msg-type field 101 with in reconfiguration message to allow the server to indicate the 102 client to send a Rebind message, which does not include a Server 103 Identifier option and allows any server to respond to the client. 105 RFC 3315 does not specify that a Reconfigure message must be sent 106 from the server with which the client most recently communicated, and 107 it does not specify which server the client should identify with a 108 Server Identifier option when the client responds to the Reconfigure 109 message. This document clarifies that the client should send a Renew 110 message in response to a Reconfigure message with a Server Identifier 111 option identifying the same server that the client would have 112 identified if the client had sent the Renew message after expiration 113 of T1. 115 2. Terminology 117 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 118 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 119 document are to be interpreted as described in [RFC2119]. 121 This document uses IPv6 and DHCPv6 terms as defined in section 4 of 122 [RFC3315]. 124 3. The Reconfigure Message option of the DHCPv6 Reconfigure Message 126 This section modifies section 22.19 of RFC 3315 to allow the 127 specification of the Rebind message in a Reconfigure message. 129 A server includes a Reconfigure Message option in a Reconfigure 130 message to indicate to the client whether the client responds with a 131 Renew, an Information-request, or a Rebind message. 133 The format of this option is: 135 0 1 2 3 136 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 1 137 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 | OPTION_RECONF_MSG | option-len | 139 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 140 | msg-type | 141 +-+-+-+-+-+-+-+-+ 143 option-code OPTION_RECONF_MSG (19). 144 option-len 1. 145 msg-type 5 for Renew message, 6 for Rebind, 11 for 146 Information-request message. 148 4. Server Behavior 150 This section updates specific text in sections 19.1, 19.2 and 19.3 of 151 RFC 3315. 153 The server MUST include a Reconfigure Message option (as defined in 154 Section 3) to select whether the client responds with a Renew 155 message, a Rebind message or an Information-Request message. 157 The Reconfigure message causes the client to initiate a Renew/Reply, 158 a Rebind/Reply message exchange or an Information-request/Reply 159 message exchange. The server interprets the receipt of a Renew, a 160 Rebind or an Information-request message (whichever was specified in 161 the original Reconfigure message) from the client as satisfying the 162 Reconfigure message request. 164 The server retransmits a Reconfigure message specifying a Rebind 165 message in the same way as described in section 19.1.2 of RFC 3315. 167 In response to a Rebind message, the server generates and sends a 168 Reply message to the client as described in sections 18.2.4 and 169 18.2.8, including options for configuration parameters. 171 The server MAY include options containing the IAs and new values for 172 other configuration parameters in the Reply message, even if those 173 IAs and parameters were not requested in the Renew message from the 174 client. 176 5. Client Behavior 178 This section updates specific text in section 19.4 of RFC 3315. 180 Upon receipt of a valid Reconfigure message, the client responds with 181 a Renew message, a Rebind message or an Information-request message 182 as indicated by the Reconfigure Message option (as defined in 183 Section 3). The client ignores the transaction-id field in the 184 received Reconfigure message. While the transaction is in progress, 185 the client silently discards any Reconfigure messages it receives. 187 When responding to a Reconfigure, the client creates and sends the 188 Rebind message in exactly the same manner as outlined in section 189 18.1.4 of RFC 3315, with the exception that the client copies the 190 Option Request option and any IA options from the Reconfigure message 191 into the Rebind message. 193 If a client is currently sending Rebind messages, as described in 194 section 18.1.4 of RFC 3315, the client ignores any received 195 Reconfigure messages. 197 The client uses the same variables and retransmission algorithm as it 198 does with Renew, Rebind or Information-request messages generated as 199 part of a client-initiated configuration exchange. See sections 200 18.1.3, 18.1.4 and 18.1.5 of RFC 3315 for details. If the client 201 does not receive a response from the server by the end of the 202 retransmission process, the client ignores and discards the 203 Reconfigure message. 205 6. Clarification of section 19.4.2, RFC 3315 207 When sending a Renew message in response to the receipt of a 208 Reconfigure message, the client MUST include a Server Identifier 209 option identifying the server the client most recently communicated 210 with. 212 7. Security Considerations 214 This document allows the Rebind message type to appear in the 215 Reconfigure Message option of a Reconfigure message so that the 216 client rebinds to a different DHCPv6 server. A malicious attacker 217 may use a faked Reconfigure message to force the client to disconnect 218 from the current server and relink to a faked server by quickly 219 responding to the client's Rebind message. These attacks may be 220 prevented by using the AUTH option [RFC3315] or Secure DHCPv6 221 [I-D.ietf-dhc-secure-dhcpv6]. 223 8. IANA Considerations 225 There are no actions for IANA associated with this document. 227 9. Change log [RFC Editor please remove] 229 Revision -05 231 Clarified description of this feature in introduction. 233 Clarified action of client if it receives a Reconfigure while sending 234 Rebind messages. 236 Revision -08 238 Add a new co-author. Refreshed expired draft. Refine the motivation 239 and suitable scenarios, also add some new security considerations. 240 Correct the intended status to standard track 242 10. References 244 10.1. Normative References 246 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 247 Requirement Levels", BCP 14, RFC 2119, March 1997. 249 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 250 and M. Carney, "Dynamic Host Configuration Protocol for 251 IPv6 (DHCPv6)", RFC 3315, July 2003. 253 10.2. Informative References 255 [I-D.ietf-dhc-secure-dhcpv6] 256 Jiang, S. and S. Shen, "Secure DHCPv6 Using CGAs", 257 draft-ietf-dhc-secure-dhcpv6-03 (work in progress), 258 June 2011. 260 Authors' Addresses 262 D. R. Evans 263 ARRIS International, Inc. 264 7912 Fairview Road 265 Boulder, CO 80303 266 USA 268 Phone: +1 303.494.0394 269 Email: N7DR@arrisi.com 271 Ralph Droms 272 Cisco Systems, Inc. 273 1414 Massachusetts Avenue 274 Boxborough, MA 01719 275 USA 277 Phone: +1 978.936.1674 278 Email: rdroms@cisco.com 280 Sheng Jiang 281 Huawei Technologies Co., Ltd 282 Huawei Building, No.3 Xinxi Rd., 283 Shang-Di Information Industry Base, Hai-Dian District, Beijing 284 P.R. China 286 Email: jiangsheng@huawei.com