4.4BSD/usr/share/man/cat1/kerberos.0
KERBEROS(1) BSD Reference Manual KERBEROS(1)
NNAAMMEE
kerberos - introduction to the Kerberos system
DDEESSCCRRIIPPTTIIOONN
The Kerberos system authenticates individual users in a
network environment. After authenticating yourself to
Kerberos, 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 work-
stations 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 _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 pass-
word. 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
message:
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 run-
ning 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 _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 run-
ning at the Laboratory for Computer Science and one run-
ning at Project Athena.
When writing a Kerberos name, the principal name is sepa-
rated 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
MIT Project Athena Kerberos Version 4.0 1
KERBEROS(1) BSD Reference Manual KERBEROS(1)
names:
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 com-
mand, Kerberos gives you an initial Kerberos _t_i_c_k_e_t. (A
Kerberos ticket is an encrypted protocol message that pro-
vides authentication.) Kerberos uses this ticket for net-
work utilities such as _r_l_o_g_i_n and _r_c_p. The ticket trans-
actions 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 instal-
lation'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 com-
mands, 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 ser-
vices: _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
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, _r_l_o_g_i_n sends your password
across the network in clear text.
MIT Project Athena Kerberos Version 4.0 2
KERBEROS(1) BSD Reference Manual KERBEROS(1)
AAUUTTHHOORRSS
Steve Miller, MIT Project Athena/Digital Equipment Corpo-
ration
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 _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 experi-
ence.
Many people contributed code and/or useful ideas, includ-
ing 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.
RREESSTTRRIICCTTIIOONNSS
COPYRIGHT 1985,1986 Massachusetts Institute of Technology
MIT Project Athena Kerberos Version 4.0 3