KERBEROS(1) UNIX System V KERBEROS(1)
NAME
kerberos - introduction to the Kerberos system
DESCRIPTION
The Kerberos system authenticates individual users in a
network environment. After authenticating yourself to
Kerberos, you can use network 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.
If you enter your username and kinit responds with this
message:
kinit(v5): Client not found in Kerberos database while
getting initial credentials
you haven't been registered as a Kerberos user. See your
system administrator.
A Kerberos name usually contains three parts. The first is
the primary, which is usually a user's or service's name.
The second is the 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 fully qualified 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 corresponds
to the Kerberos service providing authentication for the
principal.
When writing a Kerberos name, the principal name is
separated from the instance (if not null) by a slash, and
the realm (if not the local realm) follows, preceded by an
``@'' sign. The following are examples of valid Kerberos
names:
david
jennifer/admin
joeuser@BLEEP.COM
cbrown/root@FUBAR.ORG
When you authenticate yourself with Kerberos you get an
initial Kerberos ticket. (A Kerberos ticket is an encrypted
protocol message that provides authentication.) Kerberos
uses this ticket for network utilities such as rlogin and
rcp. The ticket transactions are done transparently, so you
don't have to worry about their management.
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KERBEROS(1) UNIX System V KERBEROS(1)
Note, however, that tickets expire. Privileged tickets,
such as those with the instance ``root'', 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 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 session. You should put the kdestroy
command in your .logout file so that your tickets will be
destroyed automatically when you logout. For more
information about the kinit and kdestroy commands, see the
kinit(1) and kdestroy(1) manual pages.
Kerberos tickets can be forwarded. In order to forward
tickets, you must request forwardable tickets when you
kinit. Once you have forwardable tickets, most Kerberos
programs have a command line option to forward them to the
remote host.
Currently, Kerberos support is available for the following
network services: rlogin, rsh, rcp, telnet, ftp, krdist (a
Kerberized version of rdist), ksu (a Kerberized version of
su), login, and Xdm.
SEE ALSO
kdestroy(1), kinit(1), klist(1), kpasswd(1), rsh (1),
rcp(1), rlogin(1), telnet(1), ftp(1), krdist(1), ksu(1),
sclient(1), xdm(1), des_crypt(3), hash(3), krb5strings(3),
krb5.conf(5), kdc.conf(5), kadmin(8), kadmind(8),
kdb5_util(8), telnetd(8), ftpd(8), rdistd(8), sserver(8),
klogind(8c), kshd(8c), login(8c)
BUGS
AUTHORS
Steve Miller, MIT Project Athena/Digital Equipment
Corporation
Clifford Neuman, MIT Project Athena
HISTORY
Kerberos was developed at MIT. OpenVision rewrote and
donated the administration server, which is used in the
current version of Kerberos 5.
RESTRICTIONS
Copyright 1985,1986,1989-1996,2002 Massachusetts Institute
of Technology
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