Network Working Group Senthil K Balasubramanian Internet-Draft Hewlett-Packard Company Expires: August 2004 Feb 2004 DHCP Option for Proxy Server Configuration draft-ietf-dhc-proxyserver-opt-00.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 2004. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This document defines a new Dynamic Host Configuration Protocol (DHCP) option, which can be used to configure the TCP/IP host's Proxy Server configuration for standard protocols like HTTP, FTP, NNTP, SOCKS, Gopher, SLL and etc. Proxy Server provides controlled and efficient access to the Internet by access control mechanism for different types of user requests and caching frequently accessed information (Web pages and possibly files that might have been downloaded using FTP and other protocols). Table of Contents 1. Terminologies Used . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Requirements terminology . . . . . . . . . . . . . . . . . . . 4 4. Proxy Server Configuration Option . . . . . . . . . . . . . . 5 Senthil Expires Aug, 2004 [Page 1] Internet-Draft DHCP Option for Proxy Server Configuration Feb 2004 5. Option Usage . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 9. Normative References . . . . . . . . . . . . . . . . . . . . . 6 10. Informative References . . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property . . . . . . . . . . . . . . . . . . . 7 Copyright Statements . . . . . . . . . . . . . . . . . . . . 8 1. Terminologies Used DHCP Client: A DHCP [1] client is an Internet host that uses DHCP to obtain configuration information such as network address. DHCP Server: A DHCP server is an Internet host that returns configuration parameters to DHCP clients. Proxy Server: In a enterprise network that connects to Internet, a proxy server is a server that acts as an intermediary between a workstation user and the Internet so that the enterprise can ensure security, administrative control, and caching service. A Proxy server MAY be associated with or part of a gateway server that separates the enterprise network from the outside network (Usually Internet) and a firewall server that protects the enterprise network from outside intrusion. HTTP: A protocol (RFC 2068, Hypertext Transfer Protocol, utilizing TCP) to transfer hypertext request and information between servers and browsers. FTP: A protocol (RFC 959, File Transfer Protocol Utilizing TCP) that allows users to copy file(s) between their local system and any other system, which is reachable on the network. SSL : A protocol (Secure Sockets Layer), which provides encrypted communications on the Internet. NNTP : A Protocol (RFC 977, Network News Transfer Protocol) for the distribution, inquiry, retrieval and posting of news articles over the Internet, using a reliable stream based transmission. Senthil Expires Aug, 2004 [Page 2] Internet-Draft DHCP Option for Proxy Server Configuration Feb 2004 Gopher: A Protocol (RFC 1436) designed for distributed document search and retrieval. SOCKS: SOCKSv5 is an approved standard (RFC 1928) generic, proxy protocol for TCP/IP based networking applications. The SOCKS protocol provides flexible framework for developing secure communications by easily integrating other security technologies. WAIS : A protocol (Wide Area Information Server) designed for wide-area networked-baed information system for searching, browsing and publishing. 2. Introduction The Dynamic Host Configuration Protocol [1] provides a framework for passing configuration information to hosts on a TCP/IP network. However, the configuration capability provided by DHCP does not include Proxy(HTTP, FTP, NNTP, Gopher etc.)server configuration to be used so as to have controlled and/or efficient access to the Internet from within a firewall/enterprise network. Following Figure, depicts the typical setup of a secure subnet inside a firewall with Proxy server. +---------------------------+ +-----------+ | | |Remote HTTP| | | HTTP |Server | | +------------+ +-------------+<--->+-----------+ | | Clients | |Proxy Server | | | Inside the |<------>| + | FTP +-----------+ | | Firewall | |Firewall |<--->|Remote FTP | | +------------+ +-------------+ |Server | | | ^ +-----------+ | | | | | | +-----------+ +---------------------------+ | NNTP |Remote NNTP| +------------>|Server | +-----------+ The primary use of proxies is to allow access to the WWW (World Wide Web) from within a firewall. A proxy is a special software typically runs on firewall machine, waits for a request from inside the firewall, forwards the request to the remote server outside the firewall, reads the response and then sends it back to the client. Usually, all the clients use the same proxy within a given network, which helps in efficient caching of documents that are requested by a number of clients. This behavior makes proxies attractive to clients not inside a firewall. Proxy server increases the network security and user productivity by content filtering and controlling both internal and external access to information. Also, it provides several other functionalities that are not discussed here. Senthil Expires Aug, 2004 [Page 3] Internet-Draft DHCP Option for Proxy Server Configuration Feb 2004 3. Requirements terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [2]. 4. Proxy Server Configuration Option This document defines a new DHCP Option called the Proxy Server Configuration Option. The format of the Proxy Server configuration option is: Code Len Proxy Server Configuration Sub Option +-------+------+------+------+------+------+-....-+------+ | TBD | N | a1 | a2 | a3 | a4 | | aN | +-------+------+------+------+------+------+-....-+------+ Code is TBD as per RFC-2939 [4]. The length N gives the total number of octets in the Proxy Server Configuration Sub Option. The minimum length is 8 octets. The Proxy Server Configuration sub option consists of a sequence of SubOpt/Length/Value tuples for each sub option encoded in the following manner: The format Proxy Server Configuration sub Option is: SubOpt Len IP Address Port (2 octet) +-------+------+------+------+------+------+------+------+ | t | N | a1 | a2 | a3 | a4 | port | +-------+------+------+------+------+------+------+------+ More than one Sub Option MAY be specified for the same protocol. In that case, the precedence should be given in the order in which these options are received by the client. The first one received shall be given higher priority and so on. The SubOpt field t specifies the type of Protocol and MUST be one of the protocol number. +-------------------------------+ | protocol | Number | +-------------------------------+ | HTTP | TBD | +-------------------------------+ | FTP | TBD | +-------------------------------+ | NNTP | TBD | +-------------------------------+ | Gopher | TBD | +-------------------------------+ | SSL | TBD | +-------------------------------+ | SOCKS | TBD | +-------------------------------+ | WAIS | TBD | +-------------------------------+ Senthil Expires Aug, 2004 [Page 4] Internet-Draft DHCP Option for Proxy Server Configuration Feb 2004 DHCP server should send the port field (port number) in Network Byte Order. 5. Option Usage The Proxy Server Configuration field shall NOT be terminated with a 255 sub-option. The length N of the DHCP Proxy Server Configuration Option shall include all bytes of the sub-option code/length/value tuples. The length N of the sub-options shall be the number of octets in only that sub-option's value field. The port MUST be a valid TCP/UDP port. The minimum length of a sub-option is 6 octets. The sub-options need not appear in protocol type order. 8. Security Considerations The DHCP Options defined here allow an interloper DHCP server to misdirect a client to access nonexistent/erring Proxy Server due to which the connection to the Internet might be denied. DHCP provides an authentication mechanism, as described in RFC 3118 [3], which may be used if authentication is required. 9. IANA Considerations IANA is requested to assign an option code to the Proxy Server Configuration Option and protocol numbers for the sub option. IANA is also requested to maintain a new number space for the Proxy Server Configuration sub options. 10. Acknowledgements Thanks to Srinivas Reddy and Sridhar Ramamoorthy of Satyam InfoWay for their extended help in technical Queries. 11. Normative References [1] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 12. Informative References [3] Droms, R. and W. Arbaugh, "Authentication for DHCP Messages", RFC 3118, June 2001. [4] Droms, R., "Procedures and IANA Guidelines for Definition of New DHCP Options and Message Types", BCP 43, RFC 2939, September 2000. Senthil Expires Aug, 2004 [Page 5] Internet-Draft DHCP Option for Proxy Server Configuration Feb 2004 Author's Address Senthil K Balasubramanian Hewlett Packard 29 Cunnigham Road, Bangalore India 560 052 Phone: +91 80 2205 3103 EMail: ksenthil@india.hp.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. 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