kdc.conf - Kerberos V5 KDC configuration file

kdc.conf specifies per-realm configuration data to be used by the Kerberos V5 Authentication Service and Key Distribution Center (AS/KDC). This includes database, key and per-realm defaults.

The kdc.conf file uses the same format as the krb5.conf file. For a basic description of the syntax, please refer to the krb5.conf description.

The following sections are currently used in the kdc.conf file:

[kdcdefaults]

Contains parameters which control the overall behaviour of the KDC.

[realms]

Contains subsections keyed by Kerberos realm names which describe per-realm KDC parameters.

The following relations are defined in the [kdcdefaults] section:

kdc_ports

This relation lists the ports which the Kerberos server should listen on, by default. This list is a comma separated list of integers. If this relation is not specified, the compiled-in default is usually port 88 and port 750.

v4_mode

This string specifies how the KDC should respond to Kerberos IV packets. If this relation is not specified, the compiled-in default of nopreauth is used.

Each tag in the [realms] section of the file names a Kerberos realm. The value of the tag is a subsection where the relations in that subsection define KDC parameters for that particular realm.

For each realm, the following tags may be specified in the [realms] subsection:

acl_file

This string specifies the location of the access control list (acl) file that kadmin uses to determine which principals are allowed which permissions on the database. The default value is /etc/krb5kdc/kadm5.acl.

admin_keytab

This string Specifies the location of the keytab file that kadmin uses to authenticate to the database. The default value is /etc/krb5kdc/kadm5.keytab.

database_name

This string specifies the location of the Kerberos database for this realm.

default_principal_expiration

This absolute time string specifies the default expiration date of principals created in this realm.

default_principal_flags

This flag string specifies the default attributes of principals created in this realm. The format for the string is a comma-separated list of flags, with '+' before each flag to be enabled and '-' before each flag to be disabled. The default is for postdateable, forwardable, tgt-based, renewable, proxiable, dup-skey, allow-tickets, and service to be enabled, and all others to be disabled.

There are a number of possible flags:

postdateable

Enabling this flag allows the principal to obtain postdateable tickets.

forwardable

Enabling this flag allows the principal to obtain forwardable tickets.

tgt-based

Enabling this flag allows a principal to obtain tickets based on a ticket-granting-ticket, rather than repeating the authentication process that was used to obtain the TGT.

renewable

Enabling this flag allows the principal to obtain renewable tickets.

proxiable

Enabling this flag allows the principal to obtain proxy tickets.

dup-skey

Enabling this flag allows the principal to obtain a session key for another user, permitting user-to-user authentication for this principal.

allow-tickets

Enabling this flag means that the KDC will issue tickets for this principal. Disabling this flag essentially deactivates the principal within this realm.

preauth

If this flag is enabled on a client principal, then that principal is required to preauthenticate to the KDC before receiving any tickets. On a service principal, enabling this flag means that service tickets for this principal will only be issued to clients with a TGT that has the preauthenticated ticket set.

hwauth

If this flag is enabled, then the principal is required to preauthenticate using a hardware device before receiving any tickets.

pwchange

Enabling this flag forces a password change for this principal.

service

Enabling this flag allows the the KDC to issue service tickets for this principal.

pwservice

If this flag is enabled, it marks this principal as a password change service. This should only be used in special cases, for example, if a user's password has expired, the user has to get tickets for that principal to be able to change it without going through the normal password authentication.

dict_file

This string location of the dictionary file containing strings that are not allowed as passwords. If this tag is not set or if there is no policy assigned to the principal, then no check will be done.

kadmind_port

This port number specifies the port on which the kadmind daemon is to listen for this realm.

kpasswd_port

This port number specifies the port on which the kadmind daemon is to listen for this realm.

key_stash_file

This string specifies the location where the master key has been stored with kdb5_stash.

kdc_ports

This string specifies the list of ports that the KDC is to listen to for this realm. By default, the value of kdc_ports as specified in the [kdcdefaults] section is used.

master_key_name

This string specifies the name of the principal associated with the master key. The default value is K/M.

master_key_type

This key type string represents the master key's key type.

max_life

This delta time string specifes the maximum time period that a ticket may be valid for in this realm.

max_renewable_life

This delta time string specifies the maximum time period that a ticket may be renewed for in this realm.

supported_enctypes

list of key:salt strings that specifies the default key/salt combinations of principals for this realm

kdc_supported_enctypes

specifies the permitted key-salt combinations of principals for this realm

reject_bad_transit

this boolean specifies whether or not the list of transited realms for cross-realm tickets should be checked against the transit path computed from the realm names and the [capaths] section of its krb5.conf file

/etc/krb5kdc/kdc.conf

krb5.conf(5), krb5kdc(8)