4.3BSD-Reno/share/man/cat1/kerberos.0
KERBEROS(1) 4.0 KERBEROS(1)
NNAAMMEE
kerberos - introduction to the Kerberos system
DDEESSCCRRIIPPTTIIOONN
The Kerberos system authenticates individual users in a net-
work environment. After authenticating yourself to Ker-
beros, you can use network utilities such as _r_l_o_g_i_n, _r_c_p,
and _r_s_h without having to present passwords to remote hosts
and without having to bother with ._r_h_o_s_t_s 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 sup-
port Kerberos.
Before you can use Kerberos, you must register as an Athena
user, and you must make sure you have been added to the Ker-
beros database. You can use the _k_i_n_i_t command to find out.
This command tries to log you into the Kerberos system.
_k_i_n_i_t 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 _k_i_n_i_t responds with this mes-
sage:
Principal unknown (kerberos)
you haven't been registered as a Kerberos user. See your
system administrator.
A Kerberos name contains three parts. The first is the
_p_r_i_n_c_i_p_a_l _n_a_m_e, which is usually a user's or service's name.
The second is the _i_n_s_t_a_n_c_e, 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 _r_l_o_g_i_n service running on the
machine ABC, which is different from the rlogin service run-
ning on the machine XYZ. The third part of a Kerberos name
is the _r_e_a_l_m. 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 Com-
puter 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:
Printed 7/27/90 Kerberos 1
KERBEROS(1) 4.0 KERBEROS(1)
billb
jis.admin
srz@lcs.mit.edu
treese.root@athena.mit.edu
When you authenticate yourself with Kerberos, through either
the workstation _t_o_e_h_o_l_d system or the _k_i_n_i_t command, Ker-
beros gives you an initial Kerberos _t_i_c_k_e_t. (A Kerberos
ticket is an encrypted protocol message that provides
authentication.) Kerberos uses this ticket for network util-
ities such as _r_l_o_g_i_n and _r_c_p. 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, 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 _k_i_n_i_t command to re-
authenticate yourself.
If you use the _k_i_n_i_t command to get your tickets, make sure
you use the _k_d_e_s_t_r_o_y command to destroy your tickets before
you end your login session. You should probably put the
_k_d_e_s_t_r_o_y command in your ._l_o_g_o_u_t file so that your tickets
will be destroyed automatically when you logout. For more
information about the _k_i_n_i_t and _k_d_e_s_t_r_o_y commands, see the
_k_i_n_i_t(_1) and _k_d_e_s_t_r_o_y(_1) manual pages.
Currently, Kerberos supports the following network services:
_r_l_o_g_i_n, _r_s_h, and _r_c_p. Other services are being worked on,
such as the _p_o_p mail system and NFS (network file system),
but are not yet available.
SSEEEE AALLSSOO
kdestroy(1), kinit(1), klist(1), kpasswd(1), des_crypt(3),
kerberos(3), kadmin(8)
BBUUGGSS
Kerberos will not do authentication forwarding. In other
words, if you use _r_l_o_g_i_n to login to a remote host, you can-
not use Kerberos services from that host until you authenti-
cate yourself explicitly on that host. Although you may
need to authenticate yourself on the remote host, be aware
that when you do so, _r_l_o_g_i_n sends your password across the
network in clear text.
Printed 7/27/90 Kerberos 2
KERBEROS(1) 4.0 KERBEROS(1)
AAUUTTHHOORRSS
Steve Miller, MIT Project Athena/Digital Equipment Corpora-
tion
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 ver-
sion of the database management system.
Mark Colan developed the Kerberos versions of _r_l_o_g_i_n, _r_s_h,
and _r_c_p, as well as contributing work on the servers.
John Ostlund developed the Kerberos versions of _p_a_s_s_w_d and
_u_s_e_r_r_e_g.
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 Sommer-
feld, Jennifer Steiner, Ted Ts'o, and Win Treese.
RREESSTTRRIICCTTIIOONNSS
COPYRIGHT 1985,1986 Massachusetts Institute of Technology
Printed 7/27/90 Kerberos 3