@node Setting up a realm, Kerberos 4 issues, Building and Installing, Top
@chapter Setting up a realm

A
@cindex realm
realm is an administrative domain.  Kerberos realms usually consists of
an Internet domain name in uppercase. Call your realm the same as your
Internet domain name if you do not have strong reasons for not doing so.
It will make life easier for you and everyone else.

To setup a realm you will first have to create a configuration file:
@file{/etc/krb5.conf}. The @file{krb5.conf} file can contain many
configuration options, some which are described here.

The confguration file is a hierarchial structure consisting of sections,
each containing a list of bindings (either variable assignments or
subsections). A section starts with @samp{[section-name]}.  A binding
consists of a left hand side, an equal (@samp{=}) and a right hand
side. The left hand side tag must be separated from the equal with some
whitespace. Subsections has a @samp{@{} as the first non-whitespace
character after the equal. All other bindings are treated as variable
assignments. The value of a variable extends to the end of the line.

@example
[section1]
        a-subsection = @{
                var = value1
                other-var = value with @{@}
                sub-sub-section = @{ 
                        var = 123
                @}
        @}
        var = some other value
[section2]
        var = yet another value
@end example

To denote entries in the config file, the names of sections and bindings
will be given separated with slashes (@samp{/}). The @samp{other-var}
variable will thus be @samp{section1/a-subsection/other-var}.

For in-depth information about the contents of the config file, refer to
the @file{krb5.conf} manual page. Some of the more important sections
are briefly described here. The @samp{libdefaults} section contains a
list of library configuration parameters, such as the default realm and
the timeout for kdc responses. The @samp{realms} section contains
information about specific realms, such as where they hide their
KDC. This section serves the same purpose as the Kerberos 4
@file{krb.conf} file, but can contain more information. Finally the
@samp{domain_realm} section contains a list of mappings from domains to
realms, equivalent to the Kerberos 4 @file{krb.realms} file.

To continue with the realm setup, you will have to create a config file,
with contents similar to the following.

@example
[libdefaults]
        default_realm = MY.REALM
[realms]
        MY.REALM = @{
                kdc = my.kdc
        @}
[domain_realm]
.my.domain = MY.REALM

@end example

If you use a realm name equal to your domain name, you can omit the
@samp{libdefaults}, and @samp{domain_realm}, sections.

The database library will look for the database in @file{/var/heimdal},
so you should probably create that directory.

To initialise the database use the @code{kdb_edit} program. First issue
a @kbd{init MY.REALM} command. This will create the database and insert
default principals for that realm. You can have more than one realm in
one database, so @samp{init} does not destroy any old database.

Before creating the database, @samp{init} will ask you some questions
about default and max ticket lifes. The default values should be fine.

After creating the database you should probably add yourself. You do
this with the @samp{ank} command. It takes as argument the name of a
principal. The principal should contain a realm, so if you haven't setup
a default realm, you will need to explicitly include the realm.

@example
# kdb_edit
kdb_edit> init MY.REALM
Realm max ticket life: [infinite] 
Realm max renewable ticket life: [infinite] 
Default ticket life: [1 day] 
Default renewable ticket life: [7 days] 
kdb_edit> ank me
Max ticket life [1 day]: 
Max renewable ticket [7 days]: 
Password:
Verifying password - Password:
@end example

Now start the KDC and try getting a ticket.

@example
# kdc &
# kinit me
me@@MY.REALMS's Password:
# klist
Credentials cache: /tmp/krb5cc_3008
        Principal: me@@MY.REALM

  Issued           Expires          Principal
Aug 25 07:25:55  Aug 25 17:25:55  krbtgt/MY.REALM@@MY.REALM
@end example