Network Working Group S. Drach INTERNET-DRAFT Sun Microsystems Obsoletes: draft-ietf-dhc-options-uap-01.txt November 1998 Expires May 1999 DHCP Option for User Authentication Protocol 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 view the entire list of current Internet-Drafts, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net (Northern Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast). Abstract This document defines a DHCP [1] option that contains a list of pointers to User Authentication Protocol servers that provide user authentication services for clients that conform to The Open Group Network Computing Client Technical Standard [2]. Introduction The Open Group Network Computing Client Technical Standard, a product of The Open Group's Network Computing Working Group (NCWG), defines a network computing client user authentication facility named the User Authentication Protocol (UAP). UAP provides two levels of authentication, basic and secure. Basic authentication uses the Basic Authentication mechanism defined in the HTTP 1.1 [3] specification. Secure authentication is simply basic authentication encapsulated in an SSLv3 [4] session. In both cases, a UAP client needs to obtain the IP address and port of the UAP service. Additional path information may be required, Drach [Page 1] INTERNET-DRAFT User Authentication Protocol November 1998 depending on the implementation of the service. A URL [5] is an excellent mechanism for encapsulation of this information since many UAP servers will be implemented as components within legacy HTTP/SSL servers. Most UAP clients have no local state and are configured when booted through DHCP. No existing DHCP option [6] has a data field that contains a URL. Option 72 contains a list of IP addresses for WWW servers, but it is not adequate since a port and/or path can not be specified. Hence there is a need for an option that contains a list of URLs. User Authentication Protocol Option This option specifies a list of URLs, each pointing to a user authentication service that is capable of processing authentication requests encapsulated in the User Authentication Protocol (UAP). UAP servers can accept either HTTP 1.1 or SSLv3 connections. If the list includes a URL that does not contain a port component, the normal default port is assumed (i.e., port 80 for http and port 443 for https). If the list includes a URL that does not contain a path component, the path /uap is assumed. 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Code | Length | URL list +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Code TBD Length The length of the data field (i.e., URL list) in bytes. URL list A list of one or more URLs separated by the ASCII space character (0x20). References [1] Droms, R., "Dynamic Host Configuration Protocol", RFC-2131, March 1997. [2] Technical Standard: Network Computing Client, The Open Group, Docu- ment Number C801, October 1998. Drach [Page 2] INTERNET-DRAFT User Authentication Protocol November 1998 [3] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., and T. Berners- Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC-2068, January 1997. [4] Freier, A., Karlton, P., and P. Kocher, "The SSL Protocol, Version 3.0", Netscape Communications Corp., November 1996. Standards Information Base, The Open Group, http://www.db.opengroup.org/sib.htm#SSL_3. [5] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform Resource Locators (URL)", RFC-1738, December 1994. [6] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Exten- sions", RFC-2132, March 1997. Security Considerations DHCP currently provides no authentication or security mechanisms. Potential exposures to attack are discussed in section 7 of the DHCP protocol specification. The User Authentication Protocol does not have a means to detect whether or not the client is communicating with a rogue authentica- tion service that the client contacted because it received a forged or otherwise compromised UAP option from a DHCP service whose secu- rity was compromised. Even secure authentication does not provide relief from this type of attack. This security exposure is mitigated by the environmental assumptions documented in the Network Computing Client Technical Standard. Author's Address Steve Drach Sun Microsystems, Inc. 901 San Antonio Road Palo Alto, CA 94303 Phone: (650) 960-1300 EMail: drach@sun.com Drach [Page 3]