kdc.conf(5) MIT Kerberos kdc.conf(5)
NAME
kdc.conf - Kerberos V5 KDC configuration file
The kdc.conf file supplements krb5.conf(5) for programs which are
typically only used on a KDC, such as the krb5kdc(8) and kadmind(8)
daemons and the kdb5_util(8) program. Relations documented here may also
be specified in krb5.conf; for the KDC programs mentioned, krb5.conf and
kdc.conf will be merged into a single configuration profile.
Normally, the kdc.conf file is found in the KDC state directory,
/opt/local/var/krb5kdc. You can override the default location by setting
the environment variable KRB5_KDC_PROFILE.
Please note that you need to restart the KDC daemon for any configuration
changes to take effect.
STRUCTURE
The kdc.conf file is set up in the same format as the krb5.conf(5) file.
SECTIONS
The kdc.conf file may contain the following sections:
┌──────────────┬────────────────────────────┐
│[kdcdefaults] │ Default values for KDC │
│ │ behavior │
├──────────────┼────────────────────────────┤
│[realms] │ Realm-specific database │
│ │ configuration and settings │
├──────────────┼────────────────────────────┤
│[dbdefaults] │ Default database settings │
├──────────────┼────────────────────────────┤
│[dbmodules] │ Per-database settings │
├──────────────┼────────────────────────────┤
│[logging] │ Controls how Kerberos │
│ │ daemons perform logging │
└──────────────┴────────────────────────────┘
[kdcdefaults]
Some relations in the [kdcdefaults] section specify default values for
realm variables, to be used if the [realms] subsection does not contain a
relation for the tag. See the [realms] section for the definitions of
these relations.
• host_based_services
• kdc_listen
• kdc_ports
• kdc_tcp_listen
• kdc_tcp_ports
• no_host_referral
• restrict_anonymous_to_tgt
The following [kdcdefaults] variables have no per-realm equivalent:
kdc_max_dgram_reply_size
Specifies the maximum packet size that can be sent over UDP. The
default value is 4096 bytes.
kdc_tcp_listen_backlog
(Integer.) Set the size of the listen queue length for the KDC
daemon. The value may be limited by OS settings. The default
value is 5.
spake_preauth_kdc_challenge
(String.) Specifies the group for a SPAKE optimistic challenge.
See the spake_preauth_groups variable in libdefaults for possible
values. The default is not to issue an optimistic challenge.
(New in release 1.17.)
[realms]
Each tag in the [realms] section is the name of a Kerberos realm. The
value of the tag is a subsection where the relations define KDC
parameters for that particular realm. The following example shows how to
define one parameter for the ATHENA.MIT.EDU realm:
[realms]
ATHENA.MIT.EDU = {
max_renewable_life = 7d 0h 0m 0s
}
The following tags may be specified in a [realms] subsection:
acl_file
(String.) Location of the access control list file that
kadmind(8) uses to determine which principals are allowed which
permissions on the Kerberos database. To operate without an ACL
file, set this relation to the empty string with acl_file = "".
The default value is /opt/local/var/krb5kdc/kadm5.acl. For more
information on Kerberos ACL file see kadm5.acl(5).
database_module
(String.) This relation indicates the name of the configuration
section under [dbmodules] for database-specific parameters used by
the loadable database library. The default value is the realm
name. If this configuration section does not exist, default
values will be used for all database parameters.
database_name
(String, deprecated.) This relation specifies the location of the
Kerberos database for this realm, if the DB2 module is being used
and the [dbmodules] configuration section does not specify a
database name. The default value is
/opt/local/var/krb5kdc/principal.
default_principal_expiration
(abstime string.) Specifies the default expiration date of
principals created in this realm. The default value is 0, which
means no expiration date.
default_principal_flags
(Flag string.) Specifies the default attributes of principals
created in this realm. The format for this string is a
comma-separated list of flags, with '+' before each flag that
should be enabled and '-' before each flag that should be
disabled. The postdateable, forwardable, tgt-based, renewable,
proxiable, dup-skey, allow-tickets, and service flags default to
enabled.
There are a number of possible flags:
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.
dup-skey
Enabling this flag allows the KDC to issue user-to-user
service tickets for this principal.
forwardable
Enabling this flag allows the principal to obtain
forwardable tickets.
hwauth If this flag is enabled, then the principal is required to
preauthenticate using a hardware device before receiving
any tickets.
no-auth-data-required
Enabling this flag prevents PAC or AD-SIGNEDPATH data from
being added to service tickets for the principal.
ok-as-delegate
If this flag is enabled, it hints the client that
credentials can and should be delegated when authenticating
to the service.
ok-to-auth-as-delegate
Enabling this flag allows the principal to use S4USelf
tickets.
postdateable
Enabling this flag allows the principal to obtain
postdateable tickets.
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 bit set.
proxiable
Enabling this flag allows the principal to obtain proxy
tickets.
pwchange
Enabling this flag forces a password change 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, then the user has to get tickets for that
principal without going through the normal password
authentication in order to be able to change the password.
renewable
Enabling this flag allows the principal to obtain renewable
tickets.
service
Enabling this flag allows the the KDC to issue service
tickets for this principal. In release 1.17 and later,
user-to-user service tickets are still allowed if the
dup-skey flag is set.
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.
dict_file
(String.) Location of the dictionary file containing strings that
are not allowed as passwords. The file should contain one string
per line, with no additional whitespace. If none is specified or
if there is no policy assigned to the principal, no dictionary
checks of passwords will be performed.
disable_pac
(Boolean value.) If true, the KDC will not issue PACs for this
realm, and S4U2Self and S4U2Proxy operations will be disabled.
The default is false, which will permit the KDC to issue PACs.
New in release 1.20.
encrypted_challenge_indicator
(String.) Specifies the authentication indicator value that the
KDC asserts into tickets obtained using FAST encrypted challenge
pre-authentication. New in 1.16.
host_based_services
(Whitespace- or comma-separated list.) Lists services which will
get host-based referral processing even if the server principal is
not marked as host-based by the client.
iprop_enable
(Boolean value.) Specifies whether incremental database
propagation is enabled. The default value is false.
iprop_ulogsize
(Integer.) Specifies the maximum number of log entries to be
retained for incremental propagation. The default value is 1000.
Prior to release 1.11, the maximum value was 2500. New in release
1.19.
iprop_master_ulogsize
The name for iprop_ulogsize prior to release 1.19. Its value is
used as a fallback if iprop_ulogsize is not specified.
iprop_replica_poll
(Delta time string.) Specifies how often the replica KDC polls
for new updates from the primary. The default value is 2m (that
is, two minutes). New in release 1.17.
iprop_slave_poll
(Delta time string.) The name for iprop_replica_poll prior to
release 1.17. Its value is used as a fallback if
iprop_replica_poll is not specified.
iprop_listen
(Whitespace- or comma-separated list.) Specifies the iprop RPC
listening addresses and/or ports for the kadmind(8) daemon. Each
entry may be an interface address, a port number, or an address
and port number separated by a colon. If the address contains
colons, enclose it in square brackets. If no address is
specified, the wildcard address is used. If kadmind fails to bind
to any of the specified addresses, it will fail to start. The
default (when iprop_enable is true) is to bind to the wildcard
address at the port specified in iprop_port. New in release 1.15.
iprop_port
(Port number.) Specifies the port number to be used for
incremental propagation. When iprop_enable is true, this relation
is required in the replica KDC configuration file, and this
relation or iprop_listen is required in the primary configuration
file, as there is no default port number. Port numbers specified
in iprop_listen entries will override this port number for the
kadmind(8) daemon.
iprop_resync_timeout
(Delta time string.) Specifies the amount of time to wait for a
full propagation to complete. This is optional in configuration
files, and is used by replica KDCs only. The default value is 5
minutes (5m). New in release 1.11.
iprop_logfile
(File name.) Specifies where the update log file for the realm
database is to be stored. The default is to use the database_name
entry from the realms section of the krb5 config file, with .ulog
appended. (NOTE: If database_name isn't specified in the realms
section, perhaps because the LDAP database back end is being used,
or the file name is specified in the [dbmodules] section, then the
hard-coded default for database_name is used. Determination of
the iprop_logfile default value will not use values from the
[dbmodules] section.)
kadmind_listen
(Whitespace- or comma-separated list.) Specifies the kadmin RPC
listening addresses and/or ports for the kadmind(8) daemon. Each
entry may be an interface address, a port number, or an address
and port number separated by a colon. If the address contains
colons, enclose it in square brackets. If no address is
specified, the wildcard address is used. If kadmind fails to bind
to any of the specified addresses, it will fail to start. The
default is to bind to the wildcard address at the port specified
in kadmind_port, or the standard kadmin port (749). New in
release 1.15.
kadmind_port
(Port number.) Specifies the port on which the kadmind(8) daemon
is to listen for this realm. Port numbers specified in
kadmind_listen entries will override this port number. The
assigned port for kadmind is 749, which is used by default.
key_stash_file
(String.) Specifies the location where the master key has been
stored (via kdb5_util stash). The default is
/opt/local/var/krb5kdc/.k5.REALM, where REALM is the Kerberos
realm.
kdc_listen
(Whitespace- or comma-separated list.) Specifies the UDP
listening addresses and/or ports for the krb5kdc(8) daemon. Each
entry may be an interface address, a port number, or an address
and port number separated by a colon. If the address contains
colons, enclose it in square brackets. If no address is
specified, the wildcard address is used. If no port is specified,
the standard port (88) is used. If the KDC daemon fails to bind
to any of the specified addresses, it will fail to start. The
default is to bind to the wildcard address on the standard port.
New in release 1.15.
kdc_ports
(Whitespace- or comma-separated list, deprecated.) Prior to
release 1.15, this relation lists the ports for the krb5kdc(8)
daemon to listen on for UDP requests. In release 1.15 and later,
it has the same meaning as kdc_listen if that relation is not
defined.
kdc_tcp_listen
(Whitespace- or comma-separated list.) Specifies the TCP
listening addresses and/or ports for the krb5kdc(8) daemon. Each
entry may be an interface address, a port number, or an address
and port number separated by a colon. If the address contains
colons, enclose it in square brackets. If no address is
specified, the wildcard address is used. If no port is specified,
the standard port (88) is used. To disable listening on TCP, set
this relation to the empty string with kdc_tcp_listen = "". If
the KDC daemon fails to bind to any of the specified addresses, it
will fail to start. The default is to bind to the wildcard
address on the standard port. New in release 1.15.
kdc_tcp_ports
(Whitespace- or comma-separated list, deprecated.) Prior to
release 1.15, this relation lists the ports for the krb5kdc(8)
daemon to listen on for UDP requests. In release 1.15 and later,
it has the same meaning as kdc_tcp_listen if that relation is not
defined.
kpasswd_listen
(Comma-separated list.) Specifies the kpasswd listening addresses
and/or ports for the kadmind(8) daemon. Each entry may be an
interface address, a port number, or an address and port number
separated by a colon. If the address contains colons, enclose it
in square brackets. If no address is specified, the wildcard
address is used. If kadmind fails to bind to any of the specified
addresses, it will fail to start. The default is to bind to the
wildcard address at the port specified in kpasswd_port, or the
standard kpasswd port (464). New in release 1.15.
kpasswd_port
(Port number.) Specifies the port on which the kadmind(8) daemon
is to listen for password change requests for this realm. Port
numbers specified in kpasswd_listen entries will override this
port number. The assigned port for password change requests is
464, which is used by default.
master_key_name
(String.) Specifies the name of the principal associated with the
master key. The default is K/M.
master_key_type
(Key type string.) Specifies the master key's key type. The
default value for this is aes256-cts-hmac-sha1-96. For a list of
all possible values, see Encryption types.
max_life
(duration string.) Specifies the maximum time period for which a
ticket may be valid in this realm. The default value is 24 hours.
max_renewable_life
(duration string.) Specifies the maximum time period during which
a valid ticket may be renewed in this realm. The default value is
0.
no_host_referral
(Whitespace- or comma-separated list.) Lists services to block
from getting host-based referral processing, even if the client
marks the server principal as host-based or the service is also
listed in host_based_services. no_host_referral = * will disable
referral processing altogether.
reject_bad_transit
(Boolean value.) If set to true, the KDC will check the list of
transited realms for cross-realm tickets against the transit path
computed from the realm names and the capaths section of its
krb5.conf(5) file; if the path in the ticket to be issued contains
any realms not in the computed path, the ticket will not be
issued, and an error will be returned to the client instead. If
this value is set to false, such tickets will be issued anyways,
and it will be left up to the application server to validate the
realm transit path.
If the disable-transited-check flag is set in the incoming
request, this check is not performed at all. Having the
reject_bad_transit option will cause such ticket requests to be
rejected always.
This transit path checking and config file option currently apply
only to TGS requests.
The default value is true.
restrict_anonymous_to_tgt
(Boolean value.) If set to true, the KDC will reject ticket
requests from anonymous principals to service principals other
than the realm's ticket-granting service. This option allows
anonymous PKINIT to be enabled for use as FAST armor tickets
without allowing anonymous authentication to services. The
default value is false. New in release 1.9.
spake_preauth_indicator
(String.) Specifies an authentication indicator value that the
KDC asserts into tickets obtained using SPAKE pre-authentication.
The default is not to add any indicators. This option may be
specified multiple times. New in release 1.17.
supported_enctypes
(List of key:salt strings.) Specifies the default key/salt
combinations of principals for this realm. Any principals created
through kadmin(1) will have keys of these types. The default
value for this tag is aes256-cts-hmac-sha1-96:normal
aes128-cts-hmac-sha1-96:normal. For lists of possible values, see
Keysalt lists.
[dbdefaults]
The [dbdefaults] section specifies default values for some database
parameters, to be used if the [dbmodules] subsection does not contain a
relation for the tag. See the [dbmodules] section for the definitions of
these relations.
• ldap_kerberos_container_dn
• ldap_kdc_dn
• ldap_kdc_sasl_authcid
• ldap_kdc_sasl_authzid
• ldap_kdc_sasl_mech
• ldap_kdc_sasl_realm
• ldap_kadmind_dn
• ldap_kadmind_sasl_authcid
• ldap_kadmind_sasl_authzid
• ldap_kadmind_sasl_mech
• ldap_kadmind_sasl_realm
• ldap_service_password_file
• ldap_conns_per_server
[dbmodules]
The [dbmodules] section contains parameters used by the KDC database
library and database modules. Each tag in the [dbmodules] section is the
name of a Kerberos realm or a section name specified by a realm's
database_module parameter. The following example shows how to define one
database parameter for the ATHENA.MIT.EDU realm:
[dbmodules]
ATHENA.MIT.EDU = {
disable_last_success = true
}
The following tags may be specified in a [dbmodules] subsection:
database_name
This DB2-specific tag indicates the location of the database in
the filesystem. The default is /opt/local/var/krb5kdc/principal.
db_library
This tag indicates the name of the loadable database module. The
value should be db2 for the DB2 module, klmdb for the LMDB module,
or kldap for the LDAP module.
disable_last_success
If set to true, suppresses KDC updates to the "Last successful
authentication" field of principal entries requiring
preauthentication. Setting this flag may improve performance.
(Principal entries which do not require preauthentication never
update the "Last successful authentication" field.). First
introduced in release 1.9.
disable_lockout
If set to true, suppresses KDC updates to the "Last failed
authentication" and "Failed password attempts" fields of principal
entries requiring preauthentication. Setting this flag may
improve performance, but also disables account lockout. First
introduced in release 1.9.
ldap_conns_per_server
This LDAP-specific tag indicates the number of connections to be
maintained per LDAP server.
ldap_kdc_dn and ldap_kadmind_dn
These LDAP-specific tags indicate the default DN for binding to
the LDAP server. The krb5kdc(8) daemon uses ldap_kdc_dn, while
the kadmind(8) daemon and other administrative programs use
ldap_kadmind_dn. The kadmind DN must have the rights to read and
write the Kerberos data in the LDAP database. The KDC DN must
have the same rights, unless disable_lockout and
disable_last_success are true, in which case it only needs to have
rights to read the Kerberos data. These tags are ignored if a
SASL mechanism is set with ldap_kdc_sasl_mech or
ldap_kadmind_sasl_mech.
ldap_kdc_sasl_mech and ldap_kadmind_sasl_mech
These LDAP-specific tags specify the SASL mechanism (such as
EXTERNAL) to use when binding to the LDAP server. New in release
1.13.
ldap_kdc_sasl_authcid and ldap_kadmind_sasl_authcid
These LDAP-specific tags specify the SASL authentication identity
to use when binding to the LDAP server. Not all SASL mechanisms
require an authentication identity. If the SASL mechanism
requires a secret (such as the password for DIGEST-MD5), these
tags also determine the name within the ldap_service_password_file
where the secret is stashed. New in release 1.13.
ldap_kdc_sasl_authzid and ldap_kadmind_sasl_authzid
These LDAP-specific tags specify the SASL authorization identity
to use when binding to the LDAP server. In most circumstances
they do not need to be specified. New in release 1.13.
ldap_kdc_sasl_realm and ldap_kadmind_sasl_realm
These LDAP-specific tags specify the SASL realm to use when
binding to the LDAP server. In most circumstances they do not
need to be set. New in release 1.13.
ldap_kerberos_container_dn
This LDAP-specific tag indicates the DN of the container object
where the realm objects will be located.
ldap_servers
This LDAP-specific tag indicates the list of LDAP servers that the
Kerberos servers can connect to. The list of LDAP servers is
whitespace-separated. The LDAP server is specified by a LDAP URI.
It is recommended to use ldapi: or ldaps: URLs to connect to the
LDAP server.
ldap_service_password_file
This LDAP-specific tag indicates the file containing the stashed
passwords (created by kdb5_ldap_util stashsrvpw) for the
ldap_kdc_dn and ldap_kadmind_dn objects, or for the
ldap_kdc_sasl_authcid or ldap_kadmind_sasl_authcid names for SASL
authentication. This file must be kept secure.
mapsize
This LMDB-specific tag indicates the maximum size of the two
database environments in megabytes. The default value is 128.
Increase this value to address "Environment mapsize limit reached"
errors. New in release 1.17.
max_readers
This LMDB-specific tag indicates the maximum number of concurrent
reading processes for the databases. The default value is 128.
New in release 1.17.
nosync This LMDB-specific tag can be set to improve the throughput of
kadmind and other administrative agents, at the expense of
durability (recent database changes may not survive a power outage
or other sudden reboot). It does not affect the throughput of the
KDC. The default value is false. New in release 1.17.
unlockiter
If set to true, this DB2-specific tag causes iteration operations
to release the database lock while processing each principal.
Setting this flag to true can prevent extended blocking of KDC or
kadmin operations when dumps of large databases are in progress.
First introduced in release 1.13.
The following tag may be specified directly in the [dbmodules] section to
control where database modules are loaded from:
db_module_dir
This tag controls where the plugin system looks for database
modules. The value should be an absolute path.
[logging]
The [logging] section indicates how krb5kdc(8) and kadmind(8) perform
logging. It may contain the following relations:
admin_server
Specifies how kadmind(8) performs logging.
kdc Specifies how krb5kdc(8) performs logging.
default
Specifies how either daemon performs logging in the absence of
relations specific to the daemon.
debug (Boolean value.) Specifies whether debugging messages are
included in log outputs other than SYSLOG. Debugging messages are
always included in the system log output because syslog performs
its own priority filtering. The default value is false. New in
release 1.15.
Logging specifications may have the following forms:
FILE=filename or FILE:filename
This value causes the daemon's logging messages to go to the
filename. If the = form is used, the file is overwritten. If the
: form is used, the file is appended to.
STDERR This value causes the daemon's logging messages to go to its
standard error stream.
CONSOLE
This value causes the daemon's logging messages to go to the
console, if the system supports it.
DEVICE=<devicename>
This causes the daemon's logging messages to go to the specified
device.
SYSLOG[:severity[:facility]]
This causes the daemon's logging messages to go to the system log.
For backward compatibility, a severity argument may be specified,
and must be specified in order to specify a facility. This
argument will be ignored.
The facility argument specifies the facility under which the
messages are logged. This may be any of the following facilities
supported by the syslog(3) call minus the LOG_ prefix: KERN, USER,
MAIL, DAEMON, AUTH, LPR, NEWS, UUCP, CRON, and LOCAL0 through
LOCAL7. If no facility is specified, the default is AUTH.
In the following example, the logging messages from the KDC will go to
the console and to the system log under the facility LOG_DAEMON, and the
logging messages from the administrative server will be appended to the
file /var/adm/kadmin.log and sent to the device /dev/tty04.
[logging]
kdc = CONSOLE
kdc = SYSLOG:INFO:DAEMON
admin_server = FILE:/var/adm/kadmin.log
admin_server = DEVICE=/dev/tty04
If no logging specification is given, the default is to use syslog. To
disable logging entirely, specify default = DEVICE=/dev/null.
[otp]
Each subsection of [otp] is the name of an OTP token type. The tags
within the subsection define the configuration required to forward a One
Time Password request to a RADIUS server.
For each token type, the following tags may be specified:
server This is the server to send the RADIUS request to. It can be a
hostname with optional port, an ip address with optional port, or
a Unix domain socket address. The default is
/opt/local/var/krb5kdc/<name>.socket.
secret This tag indicates a filename (which may be relative to
/opt/local/var/krb5kdc) containing the secret used to encrypt the
RADIUS packets. The secret should appear in the first line of the
file by itself; leading and trailing whitespace on the line will
be removed. If the value of server is a Unix domain socket
address, this tag is optional, and an empty secret will be used if
it is not specified. Otherwise, this tag is required.
timeout
An integer which specifies the time in seconds during which the
KDC should attempt to contact the RADIUS server. This tag is the
total time across all retries and should be less than the time
which an OTP value remains valid for. The default is 5 seconds.
retries
This tag specifies the number of retries to make to the RADIUS
server. The default is 3 retries (4 tries).
strip_realm
If this tag is true, the principal without the realm will be
passed to the RADIUS server. Otherwise, the realm will be
included. The default value is true.
indicator
This tag specifies an authentication indicator to be included in
the ticket if this token type is used to authenticate. This
option may be specified multiple times. (New in release 1.14.)
In the following example, requests are sent to a remote server via UDP:
[otp]
MyRemoteTokenType = {
server = radius.mydomain.com:1812
secret = SEmfiajf42$
timeout = 15
retries = 5
strip_realm = true
}
An implicit default token type named DEFAULT is defined for when the
per-principal configuration does not specify a token type. Its
configuration is shown below. You may override this token type to
something applicable for your situation:
[otp]
DEFAULT = {
strip_realm = false
}
PKINIT OPTIONS
NOTE:
The following are pkinit-specific options. These values may be
specified in [kdcdefaults] as global defaults, or within a
realm-specific subsection of [realms]. Also note that a
realm-specific value over-rides, does not add to, a generic
[kdcdefaults] specification. The search order is:
1. realm-specific subsection of [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/
For information about the syntax of some of these options, see Specifying
PKINIT identity information in krb5.conf(5).
pkinit_anchors
Specifies the location of trusted anchor (root) certificates which
the KDC trusts to sign client certificates. This option is
required if pkinit is to be supported by the KDC. This option may
be specified multiple times.
pkinit_dh_min_bits
Specifies the minimum number of bits the KDC is willing to accept
for a client's Diffie-Hellman key. The default is 2048.
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 value
is false.
Without this option, the KDC will only accept certificates with
the id-pkinit-san as defined in RFC 4556. 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 RFC 4556.
scLogin
If scLogin is specified, client certificates with the
Microsoft Smart Card Login EKU (id-ms-kp-sc-logon) will be
accepted.
none If none is specified, then client certificates will not be
checked to verify they have an acceptable EKU. The use of
this option is not recommended.
pkinit_identity
Specifies the location of the KDC's X.509 identity information.
This option is required if pkinit is to be supported by the KDC.
pkinit_indicator
Specifies an authentication indicator to include in the ticket if
pkinit is used to authenticate. This option may be specified
multiple times. (New in release 1.14.)
pkinit_pool
Specifies the location of intermediate certificates which may be
used by the KDC to complete the trust chain between a client's
certificate and a trusted anchor. This option may be specified
multiple times.
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 may be specified multiple times.
pkinit_require_crl_checking
The default certificate verification process will always check 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.
However, if pkinit_require_crl_checking is true and there is no
CRL information available for the issuing CA, then 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_require_freshness
Specifies whether to require clients to include a freshness token
in PKINIT requests. The default value is false. (New in release
1.17.)
ENCRYPTION TYPES
Any tag in the configuration files which requires a list of encryption
types can be set to some combination of the following strings.
Encryption types marked as "weak" and "deprecated" are available for
compatibility but not recommended for use.
┌───────────────────────────┬─────────────────────────────┐
│des3-cbc-raw │ Triple DES cbc mode raw │
│ │ (weak) │
├───────────────────────────┼─────────────────────────────┤
│des3-cbc-sha1 │ Triple DES cbc mode with │
│des3-hmac-sha1 │ HMAC/sha1 (deprecated) │
│des3-cbc-sha1-kd │ │
├───────────────────────────┼─────────────────────────────┤
│aes256-cts-hmac-sha1-96 │ AES-256 CTS mode with │
│aes256-cts aes256-sha1 │ 96-bit SHA-1 HMAC │
├───────────────────────────┼─────────────────────────────┤
│aes128-cts-hmac-sha1-96 │ AES-128 CTS mode with │
│aes128-cts aes128-sha1 │ 96-bit SHA-1 HMAC │
├───────────────────────────┼─────────────────────────────┤
│aes256-cts-hmac-sha384-192 │ AES-256 CTS mode with │
│aes256-sha2 │ 192-bit SHA-384 HMAC │
├───────────────────────────┼─────────────────────────────┤
│aes128-cts-hmac-sha256-128 │ AES-128 CTS mode with │
│aes128-sha2 │ 128-bit SHA-256 HMAC │
├───────────────────────────┼─────────────────────────────┤
│arcfour-hmac rc4-hmac │ RC4 with HMAC/MD5 │
│arcfour-hmac-md5 │ (deprecated) │
├───────────────────────────┼─────────────────────────────┤
│arcfour-hmac-exp │ Exportable RC4 with │
│rc4-hmac-exp │ HMAC/MD5 (weak) │
│arcfour-hmac-md5-exp │ │
├───────────────────────────┼─────────────────────────────┤
│camellia256-cts-cmac │ Camellia-256 CTS mode with │
│camellia256-cts │ CMAC │
├───────────────────────────┼─────────────────────────────┤
│camellia128-cts-cmac │ Camellia-128 CTS mode with │
│camellia128-cts │ CMAC │
├───────────────────────────┼─────────────────────────────┤
│des3 │ The triple DES family: │
│ │ des3-cbc-sha1 │
├───────────────────────────┼─────────────────────────────┤
│aes │ The AES family: │
│ │ aes256-cts-hmac-sha1-96, │
│ │ aes128-cts-hmac-sha1-96, │
│ │ aes256-cts-hmac-sha384-192, │
│ │ and │
│ │ aes128-cts-hmac-sha256-128 │
├───────────────────────────┼─────────────────────────────┤
│rc4 │ The RC4 family: │
│ │ arcfour-hmac │
├───────────────────────────┼─────────────────────────────┤
│camellia │ The Camellia family: │
│ │ camellia256-cts-cmac and │
│ │ camellia128-cts-cmac │
└───────────────────────────┴─────────────────────────────┘
The string DEFAULT can be used to refer to the default set of types for
the variable in question. Types or families can be removed from the
current list by prefixing them with a minus sign ("-"). Types or
families can be prefixed with a plus sign ("+") for symmetry; it has the
same meaning as just listing the type or family. For example, "DEFAULT
-rc4" would be the default set of encryption types with RC4 types
removed, and "des3 DEFAULT" would be the default set of encryption types
with triple DES types moved to the front.
While aes128-cts and aes256-cts are supported for all Kerberos
operations, they are not supported by very old versions of our GSSAPI
implementation (krb5-1.3.1 and earlier). Services running versions of
krb5 without AES support must not be given keys of these encryption types
in the KDC database.
The aes128-sha2 and aes256-sha2 encryption types are new in release 1.15.
Services running versions of krb5 without support for these newer
encryption types must not be given keys of these encryption types in the
KDC database.
KEYSALT LISTS
Kerberos keys for users are usually derived from passwords. Kerberos
commands and configuration parameters that affect generation of keys take
lists of enctype-salttype ("keysalt") pairs, known as keysalt lists.
Each keysalt pair is an enctype name followed by a salttype name, in the
format enc:salt. Individual keysalt list members are separated by comma
(",") characters or space characters. For example:
kadmin -e aes256-cts:normal,aes128-cts:normal
would start up kadmin so that by default it would generate
password-derived keys for the aes256-cts and aes128-cts encryption types,
using a normal salt.
To ensure that people who happen to pick the same password do not have
the same key, Kerberos 5 incorporates more information into the key using
something called a salt. The supported salt types are as follows:
┌──────────┬─────────────────────────────┐
│normal │ default for Kerberos │
│ │ Version 5 │
├──────────┼─────────────────────────────┤
│norealm │ same as the default, │
│ │ without using realm │
│ │ information │
├──────────┼─────────────────────────────┤
│onlyrealm │ uses only realm information │
│ │ as the salt │
├──────────┼─────────────────────────────┤
│special │ generate a random salt │
└──────────┴─────────────────────────────┘
SAMPLE KDC.CONF FILE
Here's an example of a kdc.conf file:
[kdcdefaults]
kdc_listen = 88
kdc_tcp_listen = 88
[realms]
ATHENA.MIT.EDU = {
kadmind_port = 749
max_life = 12h 0m 0s
max_renewable_life = 7d 0h 0m 0s
master_key_type = aes256-cts-hmac-sha1-96
supported_enctypes = aes256-cts-hmac-sha1-96:normal aes128-cts-hmac-sha1-96:normal
database_module = openldap_ldapconf
}
[logging]
kdc = FILE:/usr/local/var/krb5kdc/kdc.log
admin_server = FILE:/usr/local/var/krb5kdc/kadmin.log
[dbdefaults]
ldap_kerberos_container_dn = cn=krbcontainer,dc=mit,dc=edu
[dbmodules]
openldap_ldapconf = {
db_library = kldap
disable_last_success = true
ldap_kdc_dn = "cn=krbadmin,dc=mit,dc=edu"
# this object needs to have read rights on
# the realm container and principal subtrees
ldap_kadmind_dn = "cn=krbadmin,dc=mit,dc=edu"
# this object needs to have read and write rights on
# the realm container and principal subtrees
ldap_service_password_file = /etc/kerberos/service.keyfile
ldap_servers = ldaps://kerberos.mit.edu
ldap_conns_per_server = 5
}
FILES
/opt/local/var/krb5kdc/kdc.conf
SEE ALSO
krb5.conf(5), krb5kdc(8), kadm5.acl(5)
AUTHOR
MIT
COPYRIGHT
1985-2022, MIT
1.20 kdc.conf(5)
kerberos5 1.20 - Generated Sat Jun 4 16:38:55 CDT 2022