1KERBEROS(1) General Commands Manual KERBEROS(1)
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6 kerberos - introduction to the Kerberos system
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9 The Kerberos system authenticates individual users in a network envi‐
10 ronment. After authenticating yourself to Kerberos, you can use net‐
11 work utilities such as rlogin, rcp, and rsh without having to present
12 passwords to remote hosts and without having to bother with .rhosts
13 files. Note that these utilities will work without passwords only if
14 the remote machines you deal with support the Kerberos system.
15 If you enter your username and kinit responds with this message:
17 kinit(v5): Client not found in Kerberos database while getting initial
19 credentials
20 you haven't been registered as a Kerberos user. See your system admin‐
22 istrator.
23 A Kerberos name usually contains three parts. The first is the pri‐
25 mary, which is usually a user's or service's name. The second is the
26 instance, which in the case of a user is usually null. Some users may
27 have privileged instances, however, such as ``root'' or ``admin''. In
28 the case of a service, the instance is the fully qualified name of the
29 machine on which it runs; i.e. there can be an rlogin service running
30 on the machine ABC, which is different from the rlogin service running
31 on the machine XYZ. The third part of a Kerberos name is the realm.
32 The realm corresponds to the Kerberos service providing authentication
33 for the principal.
34 When writing a Kerberos name, the principal name is separated from the
36 instance (if not null) by a slash, and the realm (if not the local
37 realm) follows, preceded by an ``@'' sign. The following are examples
38 of valid Kerberos names:
39 david
41 jennifer/admin
42 joeuser@BLEEP.COM
43 cbrown/root@FUBAR.ORG
44 When you authenticate yourself with Kerberos you get an initial Ker‐
46 beros ticket. (A Kerberos ticket is an encrypted protocol message that
47 provides authentication.) Kerberos uses this ticket for network utili‐
48 ties such as rlogin and rcp. The ticket transactions are done trans‐
49 parently, so you don't have to worry about their management.
50 Note, however, that tickets expire. Privileged tickets, such as those
52 with the instance ``root'', expire in a few minutes, while tickets that
53 carry more ordinary privileges may be good for several hours or a day,
54 depending on the installation's policy. If your login session extends
55 beyond the time limit, you will have to re-authenticate yourself to
56 Kerberos to get new tickets. Use the kinit command to re-authenticate
57 yourself.
58 If you use the kinit command to get your tickets, make sure you use the
60 kdestroy command to destroy your tickets before you end your login ses‐
61 sion. You should put the kdestroy command in your .logout file so that
62 your tickets will be destroyed automatically when you logout. For more
63 information about the kinit and kdestroy commands, see the kinit(1) and
64 kdestroy(1) manual pages.
65 Kerberos tickets can be forwarded. In order to forward tickets, you
67 must request forwardable tickets when you kinit. Once you have for‐
68 wardable tickets, most Kerberos programs have a command line option to
69 forward them to the remote host.
70 Currently, Kerberos support is available for the following network ser‐
72 vices: rlogin, rsh, rcp, telnet, ftp, krdist (a Kerberized version of
73 rdist), ksu (a Kerberized version of su), login, and Xdm.
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76 kdestroy(1), kinit(1), klist(1), kpasswd(1), rsh (1), rcp(1),
77 rlogin(1), telnet(1), ftp(1), krdist(1), ksu(1), sclient(1), xdm(1),
78 des_crypt(3), hash(3), krb5strings(3), krb5.conf(5), kdc.conf(5), kad‐
79 min(8), kadmind(8), kdb5_util(8), telnetd(8), ftpd(8), rdistd(8),
80 sserver(8), klogind(8c), kshd(8c), login(8c)
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84 Steve Miller, MIT Project Athena/Digital Equipment Corporation
85 Clifford Neuman, MIT Project Athena
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88 Kerberos was developed at MIT. OpenVision rewrote and donated the
89 administration server, which is used in the current version of Kerberos
90 5.
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93 Copyright 1985,1986,1989-1996,2002 Massachusetts Institute of Technol‐
94 ogy
95 KERBEROS(1)