

KERBEROS(1)		       4.0		      KERBEROS(1)


NNAAMMEE
     kerberos - introduction to the Kerberos system


DDEESSCCRRIIPPTTIIOONN
     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:


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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.


SSEEEE AALLSSOO
     kdestroy(1), kinit(1), klist(1), kpasswd(1), des_crypt(3),
     kerberos(3), kadmin(8)

BBUUGGSS
     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.


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KERBEROS(1)		       4.0		      KERBEROS(1)


AAUUTTHHOORRSS
     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.


RREESSTTRRIICCTTIIOONNSS
     COPYRIGHT 1985,1986 Massachusetts Institute of Technology


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