.. _krb5kdc(8):

krb5kdc
=======

SYNOPSIS
--------

**krb5kdc**
[**-x** *db_args*]
[**-d** *dbname*]
[**-k** *keytype*]
[**-M** *mkeyname*]
[**-p** *portnum*]
[**-m**]
[**-r** *realm*]
[**-n**]
[**-w** *numworkers*]
[**-P** *pid_file*]


DESCRIPTION
-----------

krb5kdc is the Kerberos version 5 Authentication Service and Key
Distribution Center (AS/KDC).


OPTIONS
-------

The **-x** *db_args* option specifies the database specific arguments.
Options supported for LDAP database are:

    **-x** nconns=<number_of_connections>
        Specifies the number of connections to be maintained per
        LDAP server.

    **-x** host=<ldapuri>
        Specifies the LDAP server to connect to by a LDAP URI.

    **-x** binddn=<binddn>
        Specifies the DN of the object used by the KDC server to bind
        to the LDAP server.  This object should have the rights to
        read the realm container, principal container and the subtree
        that is referenced by the realm.

    **-x** bindpwd=<bind_password>
        Specifies the password for the above mentioned binddn.  It is
        recommended not to use this option. Instead, the password can
        be stashed using the **stashsrvpw** command of
        :ref:`kdb5_ldap_util(8)`

The **-r** *realm* option specifies the realm for which the server
should provide service.

The **-d** *dbname* option specifies the name under which the
principal database can be found.  This option does not apply to the
LDAP database.

The **-k** *keytype* option specifies the key type of the master key
to be entered manually as a password when **-m** is given; the default
is ``des-cbc-crc``.

The **-M** *mkeyname* option specifies the principal name for the master key
in the database (usually ``K/M`` in the KDC's realm).

The **-m** option specifies that the master database password should
be fetched from the keyboard rather than from a file on disk.

The **-n** option specifies that the KDC does not put itself in the
background and does not disassociate itself from the terminal.  In
normal operation, you should always allow the KDC to place itself in
the background.

The **-P** *pid_file* option tells the KDC to write its PID (followed
by a newline) into *pid_file* after it starts up.  This can be used to
identify whether the KDC is still running and to allow init scripts to
stop the correct process.

The **-p** *portnum* option specifies the default UDP port number
which the KDC should listen on for Kerberos version 5 requests.  This
value is used when no port is specified in the KDC profile and when no
port is specified in the Kerberos configuration file.  If no value is
available, then the value in ``/etc/services`` for service
``kerberos`` is used.

The **-w** *numworkers* option tells the KDC to fork *numworkers*
processes to listen to the KDC ports and process requests in parallel.
The top level KDC process (whose pid is recorded in the pid file if
the **-P** option is also given) acts as a supervisor.  The supervisor
will relay SIGHUP signals to the worker subprocesses, and will
terminate the worker subprocess if the it is itself terminated or if
any other worker process exits.

.. note:: On operating systems which do not have *pktinfo* support,
          using worker processes will prevent the KDC from listening
          for UDP packets on network interfaces created after the KDC
          starts.


EXAMPLE
-------

The KDC may service requests for multiple realms (maximum 32 realms).
The realms are listed on the command line.  Per-realm options that can
be specified on the command line pertain for each realm that follows
it and are superseded by subsequent definitions of the same option.

For example:
 ::

    krb5kdc -p 2001 -r REALM1 -p 2002 -r REALM2 -r REALM3

specifies that the KDC listen on port 2001 for REALM1 and on port 2002
for REALM2 and REALM3.  Additionally, per-realm parameters may be
specified in the :ref:`kdc.conf(5)` file.  The location of this file
may be specified by the **KRB5_KDC_PROFILE** environment variable.
Parameters specified in this file take precedence over options
specified on the command line.  See the :ref:`kdc.conf(5)` description
for further details.


ENVIRONMENT
-----------

krb5kdc uses the following environment variables:

* **KRB5_CONFIG**
* **KRB5_KDC_PROFILE**


SEE ALSO
--------

:ref:`kdb5_util(8)`, :ref:`kdc.conf(5)`, :ref:`krb5.conf(5)`,
:ref:`kdb5_ldap_util(8)`