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KERBEROS(1) General Commands Manual KERBEROS(1) NAME kerberos - introduction to the Kerberos system DESCRIPTION The Kerberos system authenticates individual users in a network envi- ronment. After authenticating yourself to Kerberos, you can use net- work utilities such as rlogin, rcp, and rsh without having to present passwords to remote hosts and without having to bother with .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. 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 kinit command to find out. This command tries to log you into the Kerberos system. 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. If you enter your username and kinit responds with this message: Principal unknown (kerberos) you haven't been registered as a Kerberos user. See your system admin- istrator. A Kerberos name contains three parts. The first is the principal name, which is usually a user's or service's name. The second is the in- stance, 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 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 realm. The realm corre- sponds to the Kerberos service providing authentication for the princi- pal. For example, at MIT there is a Kerberos running at the Laboratory for Computer Science and one running at Project Athena. 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: billb jis.admin srz@lcs.mit.edu treese.root@athena.mit.edu When you authenticate yourself with Kerberos, through either the work- station toehold system or the kinit command, Kerberos gives you an ini- tial Kerberos ticket. (A Kerberos ticket is an encrypted protocol mes- sage that provides authentication.) Kerberos uses this ticket for net- work utilities such as rlogin and rcp. The ticket transactions are done transparently, so you don't have to worry about their management. 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, de- pending 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 kinit command to re-authenticate yourself. If you use the kinit command to get your tickets, make sure you use the kdestroy command to destroy your tickets before you end your login ses- sion. You should probably put the kdestroy command in your .logout file so that your tickets will be destroyed automatically when you lo- gout. For more information about the kinit and kdestroy commands, see the kinit(1) and kdestroy(1) manual pages. Currently, Kerberos supports the following network services: rlogin, rsh, rcp, pop, ftp, telnet, AFS and NFS. SEE ALSO kdestroy(1), kinit(1), klist(1), kpasswd(1), des_crypt(3), kerberos(3), kadmin(8) BUGS Kerberos will not do authentication forwarding. In other words, if you use 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, rlogin sends your password across the net- work in clear text. AUTHORS Steve Miller, MIT Project Athena/Digital Equipment Corporation 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 man- agement system. Mark Colan developed the Kerberos versions of rlogin, rsh, and rcp, as well as contributing work on the servers. John Ostlund developed the Kerberos versions of passwd and 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. RESTRICTIONS COPYRIGHT 1985,1986 Massachusetts Institute of Technology MIT Project Athena Kerberos Version 4.0 KERBEROS(1)
NAME | DESCRIPTION | SEE ALSO | BUGS | AUTHORS | RESTRICTIONS
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