The late W. RICHARD STEVENS was the original author of UNIX Network Programming, First and Second Editions, widely recognized as the classic texts in UNIX networking. BILL FENNER is Principal Technical Staff Member at AT&T Labs in Menlo Park, CA, specializing in IP multicasting, network management, and measurement. He is one of the IETF"s Routing Area Directors, responsible for approving all routing-related documents that get published as RFCs. ANDREW M. RUDOFF, Senior Software Engineer at Sun Microsystems, specializes in networking, operating systems internals, file systems, and high availability software architecture.