.\" .\" This source code is no longer held under any constraint of USA .\" `cryptographic laws' since it was exported legally. The cryptographic .\" functions were removed from the code and a "Bones" distribution was .\" made. A Commodity Jurisdiction Request #012-94 was filed with the .\" USA State Department, who handed it to the Commerce department. The .\" code was determined to fall under General License GTDA under ECCN 5D96G, .\" and hence exportable. The cryptographic interfaces were re-added by Eric .\" Young, and then KTH proceeded to maintain the code in the free world. .\" .\"Copyright (C) 1989 by the Massachusetts Institute of Technology .\" .\"Export of this software from the United States of America is assumed .\"to require a specific license from the United States Government. .\"It is the responsibility of any person or organization contemplating .\"export to obtain such a license before exporting. .\" .\"WITHIN THAT CONSTRAINT, permission to use, copy, modify, and .\"distribute this software and its documentation for any purpose and .\"without fee is hereby granted, provided that the above copyright .\"notice appear in all copies and that both that copyright notice and .\"this permission notice appear in supporting documentation, and that .\"the name of M.I.T. not be used in advertising or publicity pertaining .\"to distribution of the software without specific, written prior .\"permission. M.I.T. makes no representations about the suitability of .\"this software for any purpose. It is provided "as is" without express .\"or implied warranty. .\" .\" $OpenBSD: kerberos.8,v 1.4 1998/02/25 15:50:56 art Exp $ .TH KERBEROS 8 "Kerberos Version 4.0" "MIT Project Athena" .SH NAME kerberos \- introduction to the Kerberos system .SH DESCRIPTION The Kerberos system authenticates individual users in a network environment. After authenticating yourself to Kerberos, you can use network utilities such as .IR rlogin , .IR rcp , and .IR rsh without having to present passwords to remote hosts and without having to bother with .I \.rhosts files. Note that these utilities will work without passwords only if the remote machines you deal with support the Kerberos system. All Athena timesharing machines and public workstations support Kerberos. .PP Before you can use Kerberos, you must register as an Athena user, and you must make sure you have been added to the Kerberos database. You can use the .I kinit command to find out. This command tries to log you into the Kerberos system. .I kinit will prompt you for a username and password. Enter your username and password. If the utility lets you login without giving you a message, you have already been registered. .PP If you enter your username and .I kinit responds with this message: .nf Principal unknown (kerberos) .fi you haven't been registered as a Kerberos user. See your system administrator. .PP A Kerberos name contains three parts. The first is the .I principal name, which is usually a user's or service's name. The second is the .I instance, which in the case of a user is usually null. Some users may have privileged instances, however, such as ``root'' or ``admin''. In the case of a service, the instance is the name of the machine on which it runs; i.e. there can be an .I rlogin service running on the machine ABC, which is different from the rlogin service running on the machine XYZ. The third part of a Kerberos name is the .I realm. The realm corresponds to the Kerberos service providing authentication for the principal. For example, at MIT there is a Kerberos running at the Laboratory for Computer Science and one running at Project Athena. .PP When writing a Kerberos name, the principal name is separated from the instance (if not null) by a period, and the realm (if not the local realm) follows, preceded by an ``@'' sign. The following are examples of valid Kerberos names: .sp .nf .in +8 billb jis.admin srz@lcs.mit.edu treese.root@athena.mit.edu .in -8 .fi .PP When you authenticate yourself with Kerberos, through either the workstation .I toehold system or the .I kinit command, Kerberos gives you an initial Kerberos .IR ticket . (A Kerberos ticket is an encrypted protocol message that provides authentication.) Kerberos uses this ticket for network utilities such as .I rlogin and .IR rcp . The ticket transactions are done transparently, so you don't have to worry about their management. .PP Note, however, that tickets expire. Privileged tickets, such as root instance tickets, expire in a few minutes, while tickets that carry more ordinary privileges may be good for several hours or a day, depending on the installation's policy. If your login session extends beyond the time limit, you will have to re-authenticate yourself to Kerberos to get new tickets. Use the .IR kinit command to re-authenticate yourself. .PP If you use the .I kinit command to get your tickets, make sure you use the .I kdestroy command to destroy your tickets before you end your login session. You should probably put the .I kdestroy command in your .I \.logout file so that your tickets will be destroyed automatically when you logout. For more information about the .I kinit and .I kdestroy commands, see the .I kinit(1) and .I kdestroy(1) manual pages. .PP Currently, Kerberos supports the following network services: .IR rlogin , .IR rsh , and .IR rcp . Other services are being worked on, such as the .IR pop mail system and NFS (network file system), but are not yet available. .SH "SEE ALSO" kdestroy(1), kinit(1), klist(1), kpasswd(1), des_crypt(3), kerberos(3), kadmin(8) .SH BUGS Kerberos will not do authentication forwarding. In other words, if you use .I rlogin to login to a remote host, you cannot use Kerberos services from that host until you authenticate yourself explicitly on that host. Although you may need to authenticate yourself on the remote host, be aware that when you do so, .I rlogin sends your password across the network in clear text. .SH AUTHORS Steve Miller, MIT Project Athena/Digital Equipment Corporation .br Clifford Neuman, MIT Project Athena The following people helped out on various aspects of the system: Jeff Schiller designed and wrote the administration server and its user interface, kadmin. He also wrote the dbm version of the database management system. Mark Colan developed the Kerberos versions of .IR rlogin , .IR rsh , and .IR rcp , as well as contributing work on the servers. John Ostlund developed the Kerberos versions of .I passwd and .IR userreg . Stan Zanarotti pioneered Kerberos in a foreign realm (LCS), and made many contributions based on that experience. Many people contributed code and/or useful ideas, including Jim Aspnes, Bob Baldwin, John Barba, Richard Basch, Jim Bloom, Bill Bryant, Rob French, Dan Geer, David Jedlinsky, John Kohl, John Kubiatowicz, Bob McKie, Brian Murphy, Ken Raeburn, Chris Reed, Jon Rochlis, Mike Shanzer, Bill Sommerfeld, Jennifer Steiner, Ted Ts'o, and Win Treese. .SH RESTRICTIONS COPYRIGHT 1985,1986 Massachusetts Institute of Technology