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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group Senthil K Balasubramanian 2 Internet-Draft Hewlett-Packard Company 3 Expires: December 2004 Michael Alexander 4 Gustaf Neumann 5 Wirtschaftsuniversitaet Wien 6 July 2004 8 DHCP Option for Proxy Server Configuration 9 draft-ietf-dhc-proxyserver-opt-01.txt 11 Status of this Memo 13 This document is an Internet-Draft and is in full conformance with 14 all provisions of Section 10 of RFC2026. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that other 18 groups may also distribute working documents as Internet-Drafts. 20 Internet-Drafts are draft documents valid for a maximum of six months 21 and may be updated, replaced, or obsoleted by other documents at any 22 time. It is inappropriate to use Internet-Drafts as reference 23 material or to cite them other than as "work in progress." 25 The list of current Internet-Drafts can be accessed at http:// 26 www.ietf.org/ietf/1id-abstracts.txt. 28 The list of Internet-Draft Shadow Directories can be accessed at 29 http://www.ietf.org/shadow.html. 31 This Internet-Draft will expire on December 2004. 33 Copyright Notice 35 Copyright (C) The Internet Society (2004). All Rights Reserved. 37 Abstract 39 This document defines a new Dynamic Host Configuration Protocol 40 (DHCP) option, which can be used to configure the TCP/IP host's Proxy 41 Server configuration for standard protocols like HTTP, FTP, NNTP, 42 SOCKS, Gopher, SLL and etc. Proxy Server provides controlled and 43 efficient access to the Internet by access control mechanism for 44 different types of user requests and caching frequently accessed 45 information (Web pages and possibly files that might have been 46 downloaded using FTP and other protocols). 48 1. Terminologies Used 50 DHCP Client: A DHCP [RFC-2131] client is an Internet host that 51 uses DHCP to obtain configuration information such as 52 network address. 54 DHCP Server: A DHCP server [RFC-2131] is an Internet host that 55 returns configuration parameters to DHCP clients. 57 Proxy Server: In a enterprise network that connects to Internet, 58 a proxy server is a server that acts as an intermediary 59 between a workstation user and the Internet so that the 60 enterprise can ensure security, administrative control, 61 and caching service. A Proxy server MAY be associated with 62 or part of a gateway server that separates the enterprise 63 network from the outside network (Usually Internet) 64 and a firewall server that protects the enterprise network 65 from outside intrusion. 67 RDF:A language (Resource Description Framework [RDF-SYN]) for 68 describing properties of web resources. 70 2. Introduction 72 The Dynamic Host Configuration Protocol [RFC-2131] provides a 73 framework for passing configuration information to hosts on a TCP/IP 74 network. This document describes a DHCP configuration option that 75 can be used to inform a DHCP client, the IP addresses of one or more 76 proxy services that are either available to it or that must be used 77 in order to access internet services, for example through a coporate 78 firewall. 80 The following diagram depicts the typical setup providing proxy 81 service to clients on a network that is protected by a firewall. 83 +---------------------------+ +-----------+ 84 | | |Remote HTTP| 85 | | HTTP |Server | 86 | +------------+ +-------------+<--->+-----------+ 87 | | Clients | |Proxy Server | 88 | | Inside the |<------>| + | FTP +-----------+ 89 | | Firewall | |Firewall |<--->|Remote FTP | 90 | +------------+ +-------------+ |Server | 91 | | ^ +-----------+ 92 | | | 93 | | | +-----------+ 94 +---------------------------+ | NNTP |Remote NNTP| 95 +------------>|Server | 96 +-----------+ 98 The primary use of proxies is to allow access to the World Wide Web 99 from within a firewall. A proxy service typically runs on firewall 100 machine. It waits for a request from inside the firewall, forwards 101 the request to the remote server outside the firewall, reads the 102 response and then sends it back to the client. Usually, all the 103 clients use the same proxy within a given network, which helps in 104 efficient caching of documents that are requested by a number of 105 clients. This behavior makes proxies attractive to clients not 106 inside a firewall. 108 A proxy server increases the network security and user productivity 109 by content filtering and controlling both internal and external 110 access to information. Also, it provides several other 111 functionalities that are not discussed here. 113 3. Requirements terminology 115 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 116 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 117 document are to be interpreted as described in [RFC 2119]. 119 4. Proxy Server Configuration Option 121 This document defines a new DHCP Option called the Proxy Server 122 Configuration Option. The format of the Proxy Server configuration 123 option is: 125 Code Len Proxy Server Configuration Entry 126 +-------+------+------+------+------+------+-....-+------+ 127 | TBD | N | e1 | e2 | e3 | e4 | | en | 128 +-------+------+------+------+------+------+-....-+------+ 130 Code is TBD and will be assigned by IANA according to [RFC-2939]. 131 The length N gives the total number of octets in the Proxy Server 132 Configuration entries. 134 The format of Proxy Server Configuration Entry can be either 135 protocol/encoding/Address/port tuple or RDF [RDF-SYN] Metadata type. 136 The minimum length is 8 octets. 138 The Proxy Server Configuration entry consists of a sequence of 139 Protocol Type (p), Encoding (e), IP address and port. 141 +--+--+--+--+--+--+--+--+ 142 |p |e |IP address |port | 143 +--+--+--+--+--+--+--+--+ 145 The Protocol(p) and encodig (e) are on octet each; each IP address is 146 four octets, and each port number is a two-octet integer encoded in 147 network byte order. 149 The protocol type(p) specifies the type of Protocol and MUST be 150 one of the following assigned numbers. 152 +-------------------------------+ 153 | protocol | Number | 154 +-------------------------------+ 155 | HTTP | 80 | 156 +-------------------------------+ 157 | FTP | 21 | 158 +-------------------------------+ 159 | NNTP | 119 | 160 +-------------------------------+ 161 | Gopher | 70 | 162 +-------------------------------+ 163 | SSL | TBD | 164 +-------------------------------+ 165 | SOCKS | 1080 | 166 +-------------------------------+ 167 | WAIS | 210 | 168 +-------------------------------+ 169 | IMAP | 220 | 170 +-------------------------------+ 171 | RDF | TBD | 172 +-------------------------------+ 174 The encoding field (e) is by default 0. Otherwise, it can either 175 have "-" or "#". 177 If it is "-", then the entry becomes a destination address for 178 exclusion from forwarding to the proxy. If it is "#", then the proxy 179 requires authentication. 181 In cases where it makes sense to specify more than one proxy server 182 for a given protocol, these proxy servers MUST be specifies as 183 additional IP addresses and ports within the same entry. The list is 184 ordered by precedence, with the most preferred proxy server appearing 185 first in the list, andthe least preferred proxy server appearing last 186 in the list. The DHCP client SHOULD honor this ordering. 188 More than one Proxy Server Configuration Entries MAY be specified in 189 the option. In that case, the list is ordered by precedence, with 190 the most preferred proxy server appearing first in the list, and the 191 least preferred proxy server appearing last in the list. The DHCP 192 client SHOULD honor this ordering. 194 The format of the Proxy Server Configuration using Metadata type is: 196 p Len RDF Metadata for the Proxy 197 +-------+------+----------------------------------+ 198 | RDF | N | RDF | 199 +-------+------+----------------------------------+ 200 The RDF payload is freeform RDF metadata for describing proxy 201 properties. The length N gives the number of octets in the RDF 202 metadata field. 204 The following entries specifies the sample format of the RDF data 205 field 207 HTTP proxy: 209 210 ]> 211 213 214 License Gate Proxy 215 John Doe 216 Duke OIT 217 Offsite Campus Resource Access Proxy 218 Service 219 Current Duke faculty, staff, and students 220 2004-06-15 221 222 224 FTP proxy: 226 227 ]> 228 230 231 License Gate FTP Proxy 232 John Doe 233 Duke OIT 234 Offsite Campus Resource Access Proxy 235 Service 236 Current Duke faculty, staff, and students 237 2004-06-15 238 239 241 As such there is no minimum length to specify a proxy using RDF 242 metadata. But the minimum sensible statement would be a literal 243 description of the proxy (License Gate Proxy) 244 giving a total of 418 characters including the overhead. 246 For example, with a description element of 60 characters, an URI of 247 80 characters plus a minimum XML/RDF syntax conformation/namespace 248 declaration of: 250 21 Octets 251 70 Octets ]> 252 64 Octets 254 109 Octets 255 81 Octets ..60 characters.. 256 18 Octets 257 10 Octets 259 ,the minimum length would be 418 octes. 261 5. Option Usage 263 The Proxy Server Configuration entries SHOULD not repeat the same 264 type of proxy entries. The port MUST be a valid TCP/UDP port. 266 6. Security Considerations 268 The DHCP Options defined here allow an intruder DHCP server to 269 misdirect a client, causing it to access a nonexistent or malicious 270 proxy server. This allows for a denial of service or man-in-the-middle 271 attack. This is a well known property of the DCHP protocol; this option 272 does not create any additional risk of such attacks. 274 DHCP provides an authentication mechanism, as described in RFC 3118 275 [3], which may be used if authentication is required. 277 7. IANA Considerations 279 IANA is requested to assign an option code to the Proxy Server 280 Configuration Option and protocol numbers for the SSL and RDF 281 protocol. 283 8. Acknowledgements 285 Thanks to Srinivas Reddy and Sridhar Ramamoorthy of Satyam InfoWay 286 for their extended help in technical Queries. 288 9. Normative References 290 [RFC-2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, 291 March 1997. 293 [RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate 294 Requirement Levels", BCP 14, RFC 2119, March 1997. 296 10. Informative References 298 [RFC-3118] Droms, R. and W. Arbaugh, "Authentication for DHCP 299 Messages", RFC 3118, June 2001. 301 [RFC-2939] Droms, R., "Procedures and IANA Guidelines for Definition 302 of New DHCP Options and Message Types", BCP 43, RFC 2939, 303 September 2000. 305 [RFC-2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 306 Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext 307 Transfer Protocol -- HTTP/1.1" RFC 2616, June 1999. 309 [RFC-959] Postel, J. and J. Reynolds, "File Transfer Protocol 310 (FTP)", STD 9, RFC 959, October 1985. 312 [RFC-1436] F. Anklesaria, M. McCahill, P. Lindner, D. Johnson, 313 D. Torrey and B. Albert, "The Internet Gopher Protocol 314 (a distributed document search and retrieval protocol)", 315 RFC 1436, March 1993. 317 [RFC-977] Kantor, B and P. Lapsley, "Network News Transfer 318 Protocol", RFC 977, February 1986. 320 [RFC-1928] Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D., and 321 L. Jones, "SOCKS Protocol V5", RFC 1928, April 1996. 323 [SSL2] Hickman, Kipp, "The SSL Protocol", Netscape Communications 324 Corp., Feb 9, 1995. 326 [SSL3] A. Frier, P. Karlton, and P. Kocher, "The SSL 3.0 327 Protocol", Netscape Communications Corp., Nov 18, 1996. 329 [RFC-1625] M. St. Pierre, J. Fullton, K. Gamiel, J. Goldman, B. Kahle, 330 J. Kunze, H. Morris, F. Schiettecatte, "WAIS over Z39.50-1988", 331 RFC 1625, June 1994. 332 [RDF-SYN] Becket, D. and B. McBride, Ed., "RDF/XML Syntax Specification", 333 W3C REC-rdf-syntax, February 2004, 334 . 336 Author's Address 338 Senthil K Balasubramanian 339 Hewlett Packard 340 29 Cunnigham Road, 341 Bangalore 342 India 560 052 344 Phone: +91 80 2205 3103 345 EMail: ksenthil@india.hp.com 346 Michael Alexander 347 Wirtschaftsuniversitaet Wien 348 Augasse 2-6 349 A-1090 Vienna, Austria 351 Phone: +43 31336 4467 352 Email: malexand@wu-wien.ac.at 354 Gustaf Neumann 355 Wirtschaftsuniversitaet Wien 356 Augasse 2-6 357 A-1090 Vienna, Austria 359 Phone: +43 31336 4671 360 Email: neumann@wu-wien.ac.at 362 Intellectual Property Statement 364 The IETF takes no position regarding the validity or scope of any 365 intellectual property or other rights that might be claimed to 366 pertain to the implementation or use of the technology described in 367 this document or the extent to which any license under such rights 368 might or might not be available; neither does it represent that it 369 has made any effort to identify any such rights. 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