1.\" $NetBSD: kerberos.8,v 1.2 2017/01/28 21:31:49 christos Exp $ 2.\" 3.\" Copyright (c) 2000 Kungliga Tekniska Högskolan 4.\" (Royal Institute of Technology, Stockholm, Sweden). 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" 3. Neither the name of the Institute nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" Id 35.\" 36.Dd Jun 27, 2013 37.Dt KERBEROS 8 38.Os 39.Sh NAME 40.Nm kerberos 41.Nd introduction to the Kerberos system 42.Sh DESCRIPTION 43Kerberos is a network authentication system. Its purpose is to 44securely authenticate users and services in an insecure network 45environment. 46.Pp 47This is done with a Kerberos server acting as a trusted third party, 48keeping a database with secret keys for all users and services 49(collectively called 50.Em principals ) . 51.Pp 52Each principal belongs to exactly one 53.Em realm , 54which is the administrative domain in Kerberos. A realm usually 55corresponds to an organisation, and the realm should normally be 56derived from that organisation's domain name. A realm is served by one 57or more Kerberos servers. 58.Pp 59The authentication process involves exchange of 60.Sq tickets 61and 62.Sq authenticators 63which together prove the principal's identity. 64.Pp 65When you login to the Kerberos system, either through the normal 66system login or with the 67.Xr kinit 1 68program, you acquire a 69.Em ticket granting ticket 70which allows you to get new tickets for other services, such as 71.Ic telnet 72or 73.Ic ftp , 74without giving your password. 75.Pp 76For more information on how Kerberos works, and other general Kerberos 77questions see the Kerberos FAQ at 78.Lk http://www.cmf.nrl.navy.mil/krb/kerberos-faq.html . 79.Pp 80For setup instructions see the Heimdal Texinfo manual. 81.Sh SEE ALSO 82.Xr ftp 1 , 83.Xr kdestroy 1 , 84.Xr kinit 1 , 85.Xr klist 1 , 86.Xr kpasswd 1 , 87.Xr telnet 1 , 88.Xr krb5 3 , 89.Xr krb5.conf 5 , 90.Xr kadmin 1 , 91.Xr kdc 8 , 92.Xr ktutil 1 93.Sh HISTORY 94The Kerberos authentication system was developed in the late 1980's as 95part of the Athena Project at the Massachusetts Institute of 96Technology. Versions one through three never reached outside MIT, but 97version 4 was (and still is) quite popular, especially in the academic 98community, but is also used in commercial products like the AFS 99filesystem. 100.Pp 101The problems with version 4 are that it has many limitations, the code 102was not too well written (since it had been developed over a long 103time), and it has a number of known security problems. To resolve many 104of these issues work on version five started, and resulted in IETF RFC 1051510 in 1993. IETF RFC 1510 was obsoleted in 2005 with IETF RFC 4120, 106also known as Kerberos clarifications. With the arrival of IETF RFC 1074120, the work on adding extensibility and internationalization have 108started (Kerberos extensions), and a new RFC will hopefully appear 109soon. 110.Pp 111This manual page is part of the 112.Nm Heimdal 113Kerberos 5 distribution, which has been in development at the Royal 114Institute of Technology in Stockholm, Sweden, since about 1997. 115