kadmind

- Kerberos administration daemon

Synopsis

/usr/lib/krb5/kadmind [-nofork] [-m] [-port port-number] [-r realm]
     [-x db_args] [-P pid_file]

Description

kadmind runs on the master key distribution center (KDC), which stores the principal and policy databases. kadmind accepts remote requests to administer the information in these databases. Remote requests are sent, for example, by kpasswd(1), gkadmin(1M), and kadmin(1M) commands, all of which are clients of kadmind. When you install a KDC, kadmind is set up in the init scripts to start automatically when the KDC is rebooted.

kadmind requires a number of configuration files to be set up for it to work:

/etc/krb5/kdc.conf

The KDC configuration file contains configuration information for the KDC and the Kerberos administration system. kadmind understands a number of configuration variables (called relations) in this file, some of which are mandatory and some of which are optional. In particular, kadmind uses the acl_file, dict_file, admin_keytab, and kadmind_port relations in the [realms] section. Refer to the kdc.conf(4) man page for information regarding the format of the KDC configuration file.

/etc/krb5/kadm5.keytab

kadmind requires a keytab (key table) containing correct entries for the kadmin/fqdn, kadmin/changepw and kadmin/changepw principals for every realm that kadmind answers requests. The keytab can be created with the kadmin(1M) or kdb5_util(1M) command. The location of the keytab is determined by the admin_keytab relation in the kdc.conf(4) file.

/etc/krb5/kadm5.acl

kadmind uses an ACL (access control list) to determine which principals are allowed to perform Kerberos administration actions. The path of the ACL file is determined by the acl_file relation in the kdc.conf file. See kdc.conf(4). For information regarding the format of the ACL file, refer to kadm5.acl(4).

The kadmind daemon will need to be restarted to reread the kadm5.acl file after it has been modified. You can do this, as root, with the following command:

# svcadm restart svc:/network/security/kadmin:default

After kadmind begins running, it puts itself in the background and disassociates itself from its controlling terminal.

kadmind can be configured for incremental database propagation. Incremental propagation allows slave KDC servers to receive principal and policy updates incrementally instead of receiving full dumps of the database. These settings can be changed in the kdc.conf(4) file:

sunw_dbprop_enable = [true | false]

Enable or disable incremental database propagation. Default is false.

sunw_dbprop_master_ulogsize = N

Specifies the maximum amount of log entries available for incremental propagation to the slave KDC servers. The maximum value that this can be is 2500 entries. Default value is 1000 entries.

The kiprop/<hostname>@<REALM> principal must exist in the master's kadm5.keytab file to enable the slave to authenticate incremental propagation from the master. In the principal syntax above, <hostname> is the master KDC's host name and <REALM> is the realm in which the master KDC resides.

Kerberos client machines can automatically migrate Unix users to the default Kerberos realm specified in the local krb5.conf(4), if the user does not have a valid kerberos account already. You achieve this by using the pam_krb5_migrate(5) service module for the service in question. The Kerberos service principal used by the client machine attempting the migration needs to be validated using the u privilege in kadm5.acl(4). When using the u privilege, kadmind validates user passwords using PAM, specifically using a PAM_SERVICE name of k5migrate by calling pam_authenticate(3PAM) and pam_acct_mgmt(3PAM).

A suitable PAM stack configuration example for k5migrate would look like:

k5migrate        auth    required        pam_unix_auth.so.1
k5migrate        account required        pam_unix_account.so.1

Options

The following options are supported:

-nofork

Specifies that kadmind does not put itself in the background and does not disassociate itself from the terminal. In normal operation, you should use the default behavior, which is to allow the daemon to put itself in the background.

-m

Specifies that the master database password should be retrieved from the keyboard rather than from the stash file. When using -m, the kadmind daemon receives the password prior to putting itself in the background. If used in combination with the -d option, you must explicitly place the daemon in the background.

-port port-number

Specifies the port on which the kadmind daemon listens for connections. The default is controlled by the kadmind_port relation in the kdc.conf(4) file.

-P pid_file

Specifies the file to which the PID of kadmind process should be written to after it starts up. This can be used to identify whether kadmind is still running and to allow init scripts to stop the correct process.

-r realm

Specifies the default realm that kadmind serves. If realm is not specified, the default realm of the host is used. kadmind answers requests for any realm that exists in the local KDC database and for which the appropriate principals are in its keytab.

-x db_args

Pass database-specific arguments to kadmind. Supported arguments are for LDAP and the Berkeley-db2 plug-in. These arguments are:

binddn=binddn

LDAP simple bind DN for authorization on the directory server. Overrides the ldap_kadmind_dn parameter setting in krb5.conf(4).

bindpwd=bindpwd

Bind password.

dbname=name

For the Berkeley-db2 plug-in, specifies a name for the Kerberos database.

nconns=num

Maximum number of server connections.

port=num

Directory server connection port.

Files

/var/krb5/principal

Kerberos principal database.

/var/krb5/principal.ulog

The update log file for incremental propagation.

/var/krb5/principal.kadm5

Kerberos administrative database containing policy information.

/var/krb5/principal.kadm5.lock

Kerberos administrative database lock file. This file works backwards from most other lock files (that is, kadmin exits with an error if this file does not exist).

/var/krb5/kadm5.dict

Dictionary of strings explicitly disallowed as passwords.

/etc/krb5/kadm5.acl

List of principals and their kadmin administrative privileges.

/etc/krb5/kadm5.keytab

Keytab for kadmin principals: kadmin/fqdn, changepw/fqdn, and kadmin/changepw.

/etc/krb5/kdc.conf

KDC configuration information.

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

kpasswd(1), svcs(1), gkadmin(1M), kadmin(1M), kadmin(1M), kdb5_util(1M), kdb5_ldap_util(1M), kproplog(1M), svcadm(1M), pam_acct_mgmt(3PAM), pam_authenticate(3PAM), kadm5.acl(4), kdc.conf(4), krb5.conf(4), attributes(5), kerberos(5), krb5envvar(5), pam_krb5_migrate(5), smf(5)

Notes

The Kerberos administration daemon (kadmind) is now compliant with the change-password standard mentioned in RFC 3244, which means it can now handle change-password requests from non-Solaris Kerberos clients.

The kadmind service is managed by the service management facility, smf(5), under the service identifier:

svc:/network/security/kadmin

Administrative actions on this service, such as enabling, disabling, or requesting restart, can be performed using svcadm(1M). The service's status can be queried using the svcs(1) command.

The -d and -p arguments are made obsolete with the -nofork and -port arguments, respectively. The -d and -p arguments might be removed in a future release of the Solaris operating system.