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 32  .\" $Id$
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 34  .Dd September 1, 2000
 35  .Dt KERBEROS 8
 36  .Os HEIMDAL
 37  .Sh NAME
 38  .Nm kerberos
 39  .Nd introduction to the Kerberos system
 40  .Sh DESCRIPTION
 41  Kerberos is a network authentication system. Its purpose is to
 42  securely authenticate users and services in an insecure network
 43  environment.
 44  .Pp
 45  This is done with a Kerberos server acting as a trusted third party,
 46  keeping a database with secret keys for all users and services
 47  (collectively called
 48  .Em principals ) .
 49  .Pp
 50  Each principal belongs to exactly one
 51  .Em realm ,
 52  which is the administrative domain in Kerberos. A realm usually
 53  corresponds to an organisation, and the realm should normally be
 54  derived from that organisation's domain name. A realm is served by one
 55  or more Kerberos servers.
 56  .Pp
 57  The authentication process involves exchange of
 58  .Sq tickets
 59  and
 60  .Sq authenticators
 61  which together prove the principal's identity.
 62  .Pp
 63  When you login to the Kerberos system, either through the normal
 64  system login or with the
 65  .Xr kinit 1
 66  program, you acquire a
 67  .Em ticket granting ticket
 68  which allows you to get new tickets for other services, such as
 69  .Ic telnet
 70  or
 71  .Ic ftp ,
 72  without giving your password.
 73  .Pp
 74  For more information on how Kerberos works, and other general Kerberos
 75  questions see the Kerberos FAQ at
 76  .Pa https://www.cmf.nrl.navy.mil/krb/kerberos-faq.html .
 77  .Pp
 78  For setup instructions see the Heimdal Texinfo manual.
 79  .Sh SEE ALSO
 80  .Xr ftp 1 ,
 81  .Xr kdestroy 1 ,
 82  .Xr kinit 1 ,
 83  .Xr klist 1 ,
 84  .Xr kpasswd 1 ,
 85  .Xr telnet 1
 86  .Sh HISTORY
 87  The Kerberos authentication system was developed in the late 1980's as
 88  part of the Athena Project at the Massachusetts Institute of
 89  Technology. Versions one through three never reached outside MIT, but
 90  version 4 was (and still is) quite popular, especially in the academic
 91  community, but is also used in commercial products like the AFS
 92  filesystem.
 93  .Pp
 94  The problems with version 4 are that it has many limitations, the code
 95  was not too well written (since it had been developed over a long
 96  time), and it has a number of known security problems. To resolve many
 97  of these issues work on version five started, and resulted in IETF RFC
 98  1510 in 1993. IETF RFC 1510 was obsoleted in 2005 with IETF RFC 4120,
 99  also known as Kerberos clarifications. With the arrival of IETF RFC
100  4120, the work on adding extensibility and internationalization have
101  started (Kerberos extensions), and a new RFC will hopefully appear
102  soon.
103  .Pp
104  This manual page is part of the
105  .Nm Heimdal
106  Kerberos 5 distribution, which has been in development at the Royal
107  Institute of Technology in Stockholm, Sweden, since about 1997.