The kdc.conf file contains KDC configuration
information, including defaults used when issuing Kerberos tickets. This
file must reside on all KDC servers. After you make any changes to
the kdc.conf file, stop and restart the krb5kdc daemon on the
KDC for the changes to take effect.
The format of the kdc.conf consists of section headings in
square brackets ([]). Each section contains zero or more
configuration variables (called relations), of the form of:
relation = relation-value
or
relation-subsection = {
relation = relation-value
relation = relation-value
}
The kdc.conf file contains one of more of the following
three sections:
kdcdefaults
Contains default values for overall behavior of the
KDC.
realms
Contains subsections for Kerberos realms, where
relation-subsection is the name of a realm. Each subsection contains
relations that define KDC properties for that particular realm,
including where to find the Kerberos servers for that realm.
logging
Contains relations that determine how Kerberos programs
perform logging.
The kdcdefaults Section
The following relation can be defined in the [kdcdefaults]
section:
kdc_ports
This relation lists the UDP ports on which the Kerberos
server should listen by default. This list is a comma-separated list of
integers. If the assigned value is 0, the Kerberos server does not listen on
any UDP port. If this relation is not specified, the Kerberos server listens
on port 750 and port 88.
kdc_tcp_ports
This relation lists the TCP ports on which the Kerberos
server should listen by default. This list is a comma-separated list of
integers. If the assigned value is 0, the Kerberos server does not listen on
any TCP port. If this relation is not specified, the Kerberos server listens
on the kdc TCP port specified in /etc/services. If this port is
not found in /etc/services the Kerberos server defaults to listen on
TCP port 88.
kdc_max_tcp_connections
This relation controls the maximum number of TCP
connections the KDC allows. The minimum value is 10. If this relation is not
specified, the Kerberos server allows a maximum of 30 TCP connections.
The realms Section
This section contains subsections for Kerberos realms, where
relation-subsection is the name of a realm. Each subsection contains
relations that define KDC properties for that particular realm.
The following relations can be specified in each subsection:
acl_file
(string) Location of the Kerberos V5 access control list
(ACL) file that kadmin uses to determine the privileges allowed
to each principal on the database. The default location is
/etc/krb5/kadm5.acl.
admin_keytab
(string) Location of the keytab file that
kadmin uses to authenticate to the database. The default location is
/etc/krb5/kadm5.keytab.
database_name
(string) Location of the Kerberos database for this
realm. The default location is /var/krb5/principal.
default_principal_expiration
(absolute time string) The default expiration date of
principals created in this realm. See the
Time Format section in
kinit(1) for the valid absolute time formats you can use for
default_principal_expiration.
default_principal_flags
(flag string) The default attributes of principals
created in this realm. Some of these flags are better to set on an individual
principal basis through the use of the attribute modifiers when using the
kadmin command to create and modify principals. However, some of these
options can be applied to all principals in the realm by adding them to the
list of flags associated with this relation.
A "flag string" is a list of one or more of the flags
listed below preceded by a minus (-) or a plus (+) character,
indicating that the option that follows should be enabled or disabled.
Flags below marked with an asterisk (*) are flags that are
best applied on an individual principal basis through the kadmin
interface rather than as a blanket attribute to be applied to all
principals.
postdateable
Create postdatable tickets.
forwardable
Create forwardable tickets.
tgt-based
Allow TGT-based requests.
renewable
Create Renewable tickets.
proxiable
Create Proxiable tickets.
dup-skey
Allow DUP_SKEY requests, this enables user-to-user
authentication.
preauth
Require the use of pre-authentication data whenever
principals request TGTs.
hwauth
Require the use of hardware-based pre-authentication data
whenever principals request TGTs.
* allow-tickets
Allow tickets to be issued for all principals.
* pwdchange
Require principal's to change their password.
* service
Enable or disable a service.
* pwservice
Mark principals as password changing principals.
An example of default_principal_flags is shown in EXAMPLES,
below.
dict_file
(string) Location of the dictionary file containing
strings that are not allowed as passwords. A principal with any password
policy is not allowed to select a password in the dictionary. The default
location is /var/krb5/kadm5.dict.
kadmind_port
(port number) The port that the kadmind daemon is
to listen on for this realm. The assigned port for kadmind is
749.
key_stash_file
(string) Location where the master key has been stored
(by kdb5_util stash). The default location is
/var/krb5/.k5.realm, where realm is the Kerberos
realm.
kdc_ports
(string) The list of UDP ports that the KDC
listens on for this realm. By default, the value of kdc_ports as
specified in the [kdcdefaults] section is used.
kdc_tcp_ports
(string) The list of TCP ports that the KDC listens on
(in addition to the UDP ports specified by kdc_ports) for this realm.
By default, the value of kdc_tcp_ports as specified in the
[kdcdefaults] section is used.
master_key_name
(string) The name of the master key.
master_key_type
(key type string) The master key's key type. This is used
to determine the type of encryption that encrypts the entries in the principal
db. des-cbc-crc, des3-cbc-md5, des3-cbc-sha1-kd,
arcfour-hmac-md5, arcfour-hmac-md5-exp,
aes128-cts-hmac-sha1-96, and aes256-cts-hmac-sha1-96 are
supported at this time (des-cbc-crc is the default). If you set this to
des3-cbc-sha1-kd all systems that receive copies of the principal db,
such as those running slave KDC's, must support des3-cbc-sha1-kd.
max_life
(delta time string) The maximum time period for which a
ticket is valid in this realm. See the
Time Format section in
kinit(1) for the valid time duration formats you can use for
max_life.
max_renewable_life
(delta time string) The maximum time period during which
a valid ticket can be renewed in this realm. See the
Time Format
section in
kinit(1) for the valid time duration formats you can use for
max_renewable_life.
sunw_dbprop_enable = [true | false]
Enable or disable incremental database propagation.
Default is false.
sunw_dbprop_master_ulogsize = N
Specifies the maximum number 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.
sunw_dbprop_slave_poll = N[s, m, h]
Specifies how often the slave KDC polls for new updates
that the master might have. Default is 2m (two minutes).
supported_enctypes
List of
key/
salt strings. The default
key/
salt combinations of principals for this realm. The
key is separated from the
salt by a colon (
:) or period
(
.). Multiple
key/
salt strings can be used by separating
each string with a space. The
salt is additional information encoded
within the key that tells what kind of key it is. Only the
normal
salt is supported at this time, for example,
des-cbc-crc:normal.
If this relation is not specified, the default setting is:
aes256-cts-hmac-sha1-96:normal \ (see note below)
aes128-cts-hmac-sha1-96:normal \
des3-cbc-sha1-kd:normal \
arcfour-hmac-md5:normal \
des-cbc-md5:normal
Note -
The unbundled Strong Cryptographic packages must be
installed for the aes256-cts-hmac-sha1-96:normal enctype to be
available for Kerberos.
reject_bad_transit
This boolean specifies whether 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(5) file.
The default for reject_bad_transit is true.
The logging Section
This section indicates how Kerberos programs perform logging. The
same relation can be repeated if you want to assign it multiple logging
methods. The following relations can be defined in the [logging]
section:
kdc
Specifies how the KDC is to perform its logging.
The default is FILE:/var/krb5/kdc.log.
admin_server
Specifies how the administration server is to perform its
logging. The default is FILE:/var/krb5/kadmin.log.
default
Specifies how to perform logging in the absence of
explicit specifications.
The [logging] relations can have the following values:
FILE:filename
or
FILE=filename
This value causes the entity's logging messages to go to
the specified file. If the `=' form is used, the file is overwritten. If the
`:' form is used, the file is appended to.
STDERR
This value sends the entity's logging messages to its
standard error stream.
CONSOLE
This value sends the entity's logging messages to the
console, if the system supports it.
DEVICE=devicename
This sends the entity's logging messages to the specified
device.
SYSLOG[:severity[:facility]]
This sends the entity's logging messages to the system
log.
The severity argument specifies the default severity of
system log messages. This default can be any of the following severities
supported by the syslog(3C) call, minus the LOG_ prefix:
LOG_EMERG, LOG_ALERT, LOG_CRIT, LOG_ERR,
LOG_WARNING, LOG_NOTICE, LOG_INFO, and
LOG_DEBUG. For example, a value of CRIT would specify
LOG_CRIT severity.
The facility argument specifies the facility under which
the messages are logged. This can be any of the following facilities
supported by the syslog(3C) call minus the LOG_ prefix:
LOG_KERN, LOG_USER, LOG_MAIL, LOG_DAEMON,
LOG_AUTH, LOG_LPR, LOG_NEWS, LOG_UUCP,
LOG_CRON, and LOG_LOCAL0 through LOG_LOCAL7.
If no severity is specified, the default is ERR. If no
facility is specified, the default is AUTH.
In the following example, the logging messages from the KDC
go to the console and to the system log under the facility LOG_DAEMON
with default severity of LOG_INFO; the logging messages from the
administration server are appended to the /var/krb5/kadmin.log file
and sent to the /dev/tty04 device.
[logging]
kdc = CONSOLE
kdc = SYSLOG:INFO:DAEMON
admin_server = FILE:/export/logging/kadmin.log
admin_server = DEVICE=/dev/tty04
The following are pkinit-specific options. These values can
be specified in [kdcdefaults] as global defaults, or within a
realm-specific subsection of [realms]. A realm-specific value
overrides, does not add to, a generic [kdcdefaults] specification.
The search order is
- 1.
- realm-specific subsection of [realms]
[realms]
[realms]
EXAMPLE.COM = {
pkinit_anchors = FILE:/usr/local/example.com.crt
}
- 2.
- generic value in the [kdcdefaults] section
[kdcdefaults]
pkinit_anchors = DIR:/usr/local/generic_trusted_cas/
pkinit_identity = URI
Specifies the location of the KDC's X.509 identity
information. This option is required if pkinit is supported by the KDC.
Valid URI types are FILE, DIR, PKCS11,
PKCS12, and ENV. See the PKINIT URI Types section for
more details.
pkinit_anchors = URI
Specifies the location of trusted anchor (root)
certificates which the KDC trusts to sign client certificates. This option is
required if pkinit is supported by the KDC. This option can be
specified multiple times. Valid URI types are FILE and
DIR. See the PKINIT URI Types section for details.
pkinit_pool
Specifies the location of intermediate certificates which
can be used by the KDC to complete the trust chain between a client's
certificate and a trusted anchor. This option can be specified multiple times.
Valid URI types are FILE and DIR. See the PKINIT URI
Types section for more details.
pkinit_revoke
Specifies the location of Certificate Revocation List
(CRL) information to be used by the KDC when verifying the validity of client
certificates. This option can be specified multiple times. The default
certificate verification process always checks the available revocation
information to see if a certificate has been revoked. If a match is found for
the certificate in a CRL, verification fails. If the certificate being
verified is not listed in a CRL, or there is no CRL present for its issuing
CA, and pkinit_require_crl_checking is false, then verification
succeeds. The only valid URI types is DIR. See the PKINIT URI
Types section for more details. If pkinit_require_crl_checking is
true and there is no CRL information available for the issuing CA,
verification fails. pkinit_require_crl_checking should be set to
true if the policy is such that up-to-date CRLs must be present for
every CA.
pkinit_dh_min_bits
Specifies the minimum number of bits the KDC is willing
to accept for a client's Diffie-Hellman key.
pkinit_allow_upn
Specifies that the KDC is willing to accept client
certificates with the Microsoft UserPrincipalName (UPN) Subject Alternative
Name (SAN). This means the KDC accepts the binding of the UPN in the
certificate to the Kerberos principal name.
The default is false.
Without this option, the KDC only accepts certificates with the
id-pkinit-san as defined in RFC4556. There is currently no option to
disable SAN checking in the KDC.
pkinit_eku_checking
This option specifies what Extended Key Usage (EKU)
values the KDC is willing to accept in client certificates. The values
recognized in the
kdc.conf file are:
kpClientAuth
This is the default value and specifies that client
certificates must have the id-pkinit-KPClientAuth EKU as defined in
RFC4556.
scLogin
If scLogin is specified, client certificates with
the Microsoft Smart Card Login EKU (id-ms-kp-sc-logon) is
accepted.
FILE:file-name[,key-file-name]
This option has context-specific behavior.
pkinit_identity
file-name specifies the name of a PEM-format file
containing the user's certificate. If key-file-name is not specified,
the user's private key is expected to be in file-name as well.
Otherwise, key-file-name is the name of the file containing the private
key.
pkinit_anchors
pkinit_pool
file-name is assumed to be the name of an
OpenSSL-style ca-bundle file. The ca-bundle file should be base-64
encoded.
DIR:directory-name
This option has context-specific behavior.
pkinit_identity
directory-name specifies a directory with files
named *.crt and *.key, where the first part of the file name is
the same for matching pairs of certificate and private key files. When a file
with a name ending with .crt is found, a matching file ending with
.key is assumed to contain the private key. If no such file is found,
then the certificate in the .crt is not used.
pkinit_anchors
pkinit_pool
directory-name is assumed to be an OpenSSL-style
hashed CA directory where each CA cert is stored in a file named
hash-of-ca-cert.#. This infrastructure is encouraged, but all
files in the directory is examined and if they contain certificates (in PEM
format), they are used.
pkinit_revoke
directory-name is assumed to be an OpenSSL-style
hashed CA directory where each revocation list is stored in a file named
hash-of-ca-cert.r#. This infrastructure is encouraged, but all
files in the directory is examined and if they contain a revocation list (in
PEM format), they are used.
PKCS12:pkcs12-file-name
pkcs12-file-name is the name of a PKCS #12 format
file, containing the user's certificate and private key.
PKCS11:[slotid=slot-id][:token=token-label][:certid=cert-id][:certlabel=cert-label]
All keyword/values are optional. PKCS11 modules (for
example,
opensc-pkcs11.so) must be installed as a crypto provider under
libpkcs11(3LIB).
slotid= and/or
token= can be specified
to force the use of a particular smard card reader or token if there is more
than one available.
certid= and/or
certlabel= can be specified
to force the selection of a particular certificate on the device. See the
pkinit_cert_match configuration option for more ways to select a
particular certificate to use for
pkinit.
ENV:environment-variable-name
environment-variable-name specifies the name of an
environment variable which has been set to a value conforming to one of the
previous values. For example, ENV:X509_PROXY, where environment
variable X509_PROXY has been set to
FILE:/tmp/my_proxy.pem.