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(See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (August 19, 2008) is 5727 days in the past. Is this intentional? 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 2396 (Obsoleted by RFC 3986) ** Obsolete normative reference: RFC 2732 (Obsoleted by RFC 3986) ** Obsolete normative reference: RFC 3315 (Obsoleted by RFC 8415) ** Downref: Normative reference to an Informational RFC: RFC 3617 Summary: 5 errors (**), 0 flaws (~~), 1 warning (==), 7 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 DHC T. Huth 3 Internet-Draft J. Freimann 4 Intended status: Standards Track IBM Deutschland Research & 5 Expires: February 20, 2009 Development GmbH 6 August 19, 2008 8 DHCPv6 option for network boot 9 draft-ietf-dhc-dhcpv6-opt-netboot-00 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of 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 February 20, 2009. 36 Abstract 38 The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) provides a 39 framework for passing configuration information to nodes on a 40 network. This document describes a new option for DHCPv6 to convey 41 information, required for network booting, to the nodes. 43 Table of Contents 45 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 46 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3 47 3. Netboot option format . . . . . . . . . . . . . . . . . . . . . 3 48 4. Suboption: boot file Uniform Resource Locator (URL) . . . . . . 4 49 5. Appearance of these options . . . . . . . . . . . . . . . . . . 6 50 6. Boot protocol considerations . . . . . . . . . . . . . . . . . 6 51 7. IANA considerations . . . . . . . . . . . . . . . . . . . . . . 6 52 8. Security considerations . . . . . . . . . . . . . . . . . . . . 7 53 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 54 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 55 10.1. Normative References . . . . . . . . . . . . . . . . . . . 7 56 10.2. Informative References . . . . . . . . . . . . . . . . . . 8 57 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 58 Intellectual Property and Copyright Statements . . . . . . . . . . 9 60 1. Introduction 62 Network booting means that a node which should be booted fetches the 63 files required for booting via its network device from a server. 64 Network booting is, for example, very useful in environments where 65 the administrators have to maintain a large number of nodes. Since 66 all boot and configuration files are stored on a central server, the 67 maintenance of all nodes can be kept simple this way. 69 A typical boot file would be, for example, an operating system kernel 70 or a boot loader program. To be able to download such a file, the 71 firmware (BIOS) running on the client node must be provided with 72 information such as: the server on which the boot files can be found, 73 the protocol to be used for the download (for example TFTP [RFC1350]) 74 and the name of the boot file. Since some kernels or boot loaders 75 need to be provided with additional parameters, there should also be 76 the possibility to pass additional parameters along with the server 77 address, the protocol and the file name. 79 DHCPv6 allows client nodes to ask a DHCPv6 server for configuration 80 parameters. Contrary to its IPv4 predecessor, DHCPv6 does not define 81 a way to query network boot options such as the IPv6 address of a 82 boot file server and boot file names. Therefore this document 83 defines a new DHCPv6 option which is required for network booting 84 clients. 86 2. Conventions 88 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 89 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 90 document are to be interpreted as described in RFC 2119 [RFC2119]. 92 Terminology specific to IPv6 and DHCPv6 are used in the same way as 93 defined in the "Terminology" sections of RFC 3315 [RFC3315]. 95 3. Netboot option format 97 The netboot option is used as an encapsulation for suboptions which 98 carry the actual information needed to boot a client. This option 99 will be used by clients to request boot information from a server. 101 0 1 2 3 102 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 1 103 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 104 | OPT_NET_BOOT | option-len | 105 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 106 | suboption-code 1 | subopt-len | 107 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 108 | subopt-data 1 (variable length) | 109 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 110 . . 111 . . 112 . . 113 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 114 | suboption-code n | subopt-len | 115 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 116 | subopt-data n (variable length) | 117 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 119 option-code OPT_NET_BOOT (tbd). 121 option-len Length of the netboot option in octets. 123 Multiple occurences of each suboption-type can occur within a netboot 124 option (for example when more than one boot server is available). 125 Clients MUST process the suboptions in the order in which they appear 126 in the message sent by the server. 128 So far, only one suboption has been defined, SUBOPT_BOOTFILE_URL, 129 which is described in Section 4. Other suboptions might be defined 130 in future RFCs. 132 4. Suboption: boot file Uniform Resource Locator (URL) 134 This suboption consists of multiple null-terminated strings. It is 135 used to convey an URL to a boot file together with additional 136 parameters for the boot file (e.g. parameters for the kernel or boot 137 loader program). 139 Since multiple occurrences of SUBOPT_BOOTFILE_URL can be present in a 140 single OPT_NETBOOT message, clients MUST process them in the order in 141 which they appear within the message. For example in the case of a 142 boot file URL the first file should be downloaded and executed. In 143 case of a failure the process should continue with the second one and 144 so on. 146 0 1 2 3 147 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 1 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 149 | SUBOPT_BOOTFILE_URL | subopt-len | 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 151 | bootfile-url | 152 . (variable) . 153 | | '\0' | 154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 155 | parameter 1 | 156 . (variable) . 157 | | '\0' | 158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 159 . . 160 . . 161 . . 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 | parameter n | 164 . (variable) . 165 | | '\0' | 166 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 168 Format description: 170 suboption-code SUBOPT_BOOTFILE_URL (tbd). 172 suboption-len Length of the bootfile suboption in octets. 174 bootfile-url This NULL-terminated ASCII string is the URL 175 (conforming to [RFC2396]) to a boot file. This 176 string starts with the protocol which is used for 177 downloading. Separated by '://', the hostname or 178 IPv6 address of the server hosting the boot file 179 (see also the note below), the path, file name and 180 query parts of the URL follow. 182 parameters 1...n These NULL-terminated ASCII strings are parameters 183 needed for booting, e.g. kernel parameters. In 184 cases where no parameters are needed, everything 185 but the boot file URL can be omitted. Parameters 186 following the boot file name should be directly 187 related to the boot file (kernel) itself. 189 Note about the bootfile-url: This string can either contain a 190 hostname or an IPv6 address to specify the server where the boot file 191 should be downloaded from. All clients which implement support for 192 the SUBOPT_BOOTFILE_URL suboption MUST be able to handle IPv6 193 addresses here. The IPv6 address in the URL then MUST be enclosed in 194 "[" and "]" characters, conforming to [RFC2732]. Clients SHOULD also 195 be able to handle hostnames in the URLs. However, in this case the 196 firmware implementation on the client machine must support DNS, too. 197 Due to size limitations, this might not be possible in all firmware 198 implementations, so support for hostnames in the URLs is only 199 optional. 201 5. Appearance of these options 203 The netboot option MUST NOT appear in DHCPv6 messages other than the 204 types Solicit, Advertise, Request, Renew, Rebind, Information-Request 205 and Reply. 207 The number of the netboot option MAY appear in the Option Request 208 Option in the DHCPv6 message types Solicit, Request, Renew, Rebind, 209 Information-Request and Reconfigure. 211 The bootfile suboption MUST appear only in the netboot option. 213 6. Boot protocol considerations 215 RFC 906 [RFC906] suggests to use TFTP for bootstrap loading. Because 216 it is easy to implement this protocol in firmware (where one has to 217 deal with size and complexity constraints), this is still the 218 recommended protocol for network booting, so every firmware 219 implementation SHOULD at least support this protocol. The boot file 220 URLs then must be specified according to RFC 3617 [RFC3617]. 222 In some cases however, it might also be useful to use other protocols 223 like FTP or HTTP for network booting, so a firmware implementation 224 can support these protocols, too. Then it is up to the network 225 administrator to choose the appropriate boot protocol for the 226 network, and to specify the right boot file URLs in the DHCPv6 227 configuration file. 229 7. IANA considerations 231 The following options need to be assigned by the IANA from the option 232 number space defined in the chapter 22 of the DHCPv6 RFC [RFC3315]. 234 +---------------------+-------+--------------+ 235 | Option name | Value | Specified in | 236 +---------------------+-------+--------------+ 237 | OPT_NET_BOOT | tbd | Section 3 | 238 | SUBOPT_BOOTFILE_URL | tbd | Section 4 | 239 +---------------------+-------+--------------+ 241 8. Security considerations 243 The new DHCPv6 option described in this document could be sent in 244 untrusted networks by malicious people with a fake DHCPv6 server to 245 confuse the booting clients. The clients could be provided with a 246 wrong URL so that the boot either fails, or even worse, the client 247 boots the wrong operating system which has been provided by a 248 malicious file server. To prevent this kind of attack, clients 249 SHOULD use authentication of DHCPv6 messages (see chapter 21. in RFC 250 3315 [RFC3315]). 252 Note also that DHCPv6 messages are sent unencrypted by default. So 253 the boot file URL options are sent unencrypted over the network, too. 254 This can become a security risk since the URLs can contain sensitive 255 information like user names and passwords (for example a URL like 256 "ftp://username:password@servername/path/file"). At the current 257 point in time, there is no possibility to send encrypted DHCPv6 258 messages, so it is strongly recommended not to use sensitive 259 information in the URLs in untrusted networks. 261 9. Acknowledgements 263 The authors would like to thank Ketan P. Pancholi for corrections and 264 suggestions. 266 Vijayabhaskar Kalusivalingam and Senthil Balasubramanian published a 267 similar draft for IPv6 network booting some years ago (available at 268 http://tools.ietf.org/html/draft-ietf-dhc-dhcpv6-opt-rboot-00), which 269 however was abandoned for unknown reasons. 271 10. References 273 10.1. Normative References 275 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 276 Requirement Levels", BCP 14, RFC 2119, March 1997. 278 [RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 279 Resource Identifiers (URI): Generic Syntax", RFC 2396, 280 August 1998. 282 [RFC2732] Hinden, R., Carpenter, B., and L. Masinter, "Format for 283 Literal IPv6 Addresses in URL's", RFC 2732, December 1999. 285 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 286 and M. Carney, "Dynamic Host Configuration Protocol for 287 IPv6 (DHCPv6)", RFC 3315, July 2003. 289 [RFC3617] Lear, E., "Uniform Resource Identifier (URI) Scheme and 290 Applicability Statement for the Trivial File Transfer 291 Protocol (TFTP)", RFC 3617, October 2003. 293 10.2. Informative References 295 [RFC1350] Sollins, K., "The TFTP Protocol (Revision 2)", STD 33, 296 RFC 1350, July 1992. 298 [RFC906] Finlayson, R., "Bootstrap Loading using TFTP", RFC 906, 299 June 1984. 301 Authors' Addresses 303 Thomas H. Huth 304 IBM Deutschland Research & Development GmbH 305 Schoenaicher Strasse 220 306 Boeblingen 71032 307 Germany 309 Phone: +49-7031-16-2183 310 Email: thuth@de.ibm.com 312 Jens T. Freimann 313 IBM Deutschland Research & Development GmbH 314 Schoenaicher Strasse 220 315 Boeblingen 71032 316 Germany 318 Phone: +49-7031-16-1122 319 Email: jfrei@de.ibm.com 321 Full Copyright Statement 323 Copyright (C) The IETF Trust (2008). 325 This document is subject to the rights, licenses and restrictions 326 contained in BCP 78, and except as set forth therein, the authors 327 retain all their rights. 329 This document and the information contained herein are provided on an 330 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 331 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 332 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 333 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 334 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 335 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 337 Intellectual Property 339 The IETF takes no position regarding the validity or scope of any 340 Intellectual Property Rights or other rights that might be claimed to 341 pertain to the implementation or use of the technology described in 342 this document or the extent to which any license under such rights 343 might or might not be available; nor does it represent that it has 344 made any independent effort to identify any such rights. 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