NAME

     kerberos — introduction to the Kerberos system

DESCRIPTION

     Kerberos is a network authentication system. Its purpose is to securely authenticate users
     and services in an insecure network environment.

     This is done with a Kerberos server acting as a trusted third party, keeping a database with
     secret keys for all users and services (collectively called principals).

     Each principal belongs to exactly one realm, which is the administrative domain in Kerberos.
     A realm usually corresponds to an organisation, and the realm should normally be derived
     from that organisation's domain name. A realm is served by one or more Kerberos servers.

     The authentication process involves exchange of ‘tickets’ and ‘authenticators’ which
     together prove the principal's identity.

     When you login to the Kerberos system, either through the normal system login or with the
     kinit(1) program, you acquire a ticket granting ticket which allows you to get new tickets
     for other services, such as telnet or ftp, without giving your password.

     For more information on how Kerberos works, and other general Kerberos questions see the
     Kerberos FAQ at http://www.cmf.nrl.navy.mil/krb/kerberos-faq.html.

     For setup instructions see the Heimdal Texinfo manual.

SEE ALSO

     ftp(1), kdestroy(1), kinit(1), klist(1), kpasswd(1), telnet(1), krb5(3), krb5.conf(5),
     kadmin(1), kdc(8), ktutil(1)

HISTORY

     The Kerberos authentication system was developed in the late 1980's as part of the Athena
     Project at the Massachusetts Institute of Technology. Versions one through three never
     reached outside MIT, but version 4 was (and still is) quite popular, especially in the
     academic community, but is also used in commercial products like the AFS filesystem.

     The problems with version 4 are that it has many limitations, the code was not too well
     written (since it had been developed over a long time), and it has a number of known
     security problems. To resolve many of these issues work on version five started, and
     resulted in IETF RFC 1510 in 1993. IETF RFC 1510 was obsoleted in 2005 with IETF RFC 4120,
     also known as Kerberos clarifications. With the arrival of IETF RFC 4120, the work on adding
     extensibility and internationalization have started (Kerberos extensions), and a new RFC
     will hopefully appear soon.

     This manual page is part of the Heimdal Kerberos 5 distribution, which has been in
     development at the Royal Institute of Technology in Stockholm, Sweden, since about 1997.