INTERNET-DRAFT Stuart L. Kwan Microsoft Corporation March 1997 Expires September 1997 DHCP Option for Proxy Client Configuration File Status of this Memo This document is an Internet-Draft. 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.'' To learn the current status of any Internet-Draft, please check the ``1id-abstracts.txt'' listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast). Abstract Application-level gateways are used on networks to provide controlled access to the Internet. Clients in those networks must be configured with the name or address of available proxy servers, the list of local domain names, and other proxy client configuration information before they can access the Internet. The defacto method of proxy client configuration is the download of a script or configuration file named by a URL. This document describes a DHCP option in which to transmit this URL to a proxy client. Expires September 1997 [Page 1] INTERNET-DRAFT Proxy Client Configuration Option February 1997 1. Introduction Application-level gateways are used on networks to provide controlled access to the Internet. Clients in those networks must be configured with the names or addresses of available proxy servers, the list of local domain names, and other proxy client configuration information before they can access the Internet. The defacto method of proxy client configuration is the download of a script or configuration file named by a URL. The URL scheme is flexible, but suffers from two limitations. One, the URL must typically be hand-typed into each proxy client on each host. Two, the configuration settings are usually only useful on one network. If the host is mobile and travels to a different network with different proxy servers, or is connected directly to the Internet, then the persisted proxy settings will be invalid and the URL no longer reachable or valid. This document describes a DHCP option in which to transmit this URL to a proxy client. Using this option network administrators can select the proxy client configuration on a per-network basis. Roaming hosts can discover if they have been connected to a network with proxy-controlled Internet access. 2. Proxy Client Configuration File The format and interpretation of the file that is referenced by the proxy configuration URL is not discussed in this document. Currently the interpretation of this file is non-standard and vendor-specific. Until there exists a standard for proxy client configuration, it is recommended that proxy client software search all the URLs sent in the DHCP option for a configuration file that the software can understand. Expires September 1997 [Page 2] INTERNET-DRAFT Proxy Client Configuration Option February 1997 3. Proxy-Client Configuration URL Option This option specifies a list of URLs from which proxy clients may obtain proxy client configuration files. URLs SHOULD be listed in order of preference. The code for this option is TBD. Its minimum length is 1. Code Len Proxy Client Configuration URLs +-----+-----+-----+-----+-----+-----+--- | TBD | n | n1 | n2 | n3 | n4 | ... +-----+-----+-----+-----+-----+-----+--- 4. Security Considerations Security issues are not discussed in this document. 5. Acknowledgements The author would like to thank Yaron Goland, Arnold Miller, and Hadi Partovi for their assistance in creating this document. 6. References [1] Droms, R., "Dynamic Host Configuration Protocol", RFC 1541, Bucknell University, October 1993. 7. Author Information Stuart L. Kwan Microsoft Corporation One Microsoft Way Redmond, WA 98052-6399 Phone: 1.206.936.0564 Email: skwan@microsoft.com Expires September 1997 [Page 3]