Provided by: sssd-krb5_1.11.5-1ubuntu3_amd64 bug

NAME

       sssd-krb5 - the configuration file for SSSD

DESCRIPTION

       This manual page describes the configuration of the Kerberos 5 authentication backend for
       sssd(8). For a detailed syntax reference, please refer to the “FILE FORMAT” section of the
       sssd.conf(5) manual page.

       The Kerberos 5 authentication backend contains auth and chpass providers. It must be
       paired with an identity provider in order to function properly (for example, id_provider =
       ldap). Some information required by the Kerberos 5 authentication backend must be provided
       by the identity provider, such as the user's Kerberos Principal Name (UPN). The
       configuration of the identity provider should have an entry to specify the UPN. Please
       refer to the man page for the applicable identity provider for details on how to configure
       this.

       This backend also provides access control based on the .k5login file in the home directory
       of the user. See .k5login(5) for more details. Please note that an empty .k5login file
       will deny all access to this user. To activate this feature, use 'access_provider = krb5'
       in your SSSD configuration.

       In the case where the UPN is not available in the identity backend, sssd will construct a
       UPN using the format username@krb5_realm.

CONFIGURATION OPTIONS

       If the auth-module krb5 is used in an SSSD domain, the following options must be used. See
       the sssd.conf(5) manual page, section “DOMAIN SECTIONS”, for details on the configuration
       of an SSSD domain.

       krb5_server, krb5_backup_server (string)
           Specifies the comma-separated list of IP addresses or hostnames of the Kerberos
           servers to which SSSD should connect, in the order of preference. For more information
           on failover and server redundancy, see the “FAILOVER” section. An optional port number
           (preceded by a colon) may be appended to the addresses or hostnames. If empty, service
           discovery is enabled; for more information, refer to the “SERVICE DISCOVERY” section.

           When using service discovery for KDC or kpasswd servers, SSSD first searches for DNS
           entries that specify _udp as the protocol and falls back to _tcp if none are found.

           This option was named “krb5_kdcip” in earlier releases of SSSD. While the legacy name
           is recognized for the time being, users are advised to migrate their config files to
           use “krb5_server” instead.

       krb5_realm (string)
           The name of the Kerberos realm. This option is required and must be specified.

       krb5_kpasswd, krb5_backup_kpasswd (string)
           If the change password service is not running on the KDC, alternative servers can be
           defined here. An optional port number (preceded by a colon) may be appended to the
           addresses or hostnames.

           For more information on failover and server redundancy, see the “FAILOVER” section.
           NOTE: Even if there are no more kpasswd servers to try, the backend is not switched to
           operate offline if authentication against the KDC is still possible.

           Default: Use the KDC

       krb5_ccachedir (string)
           Directory to store credential caches. All the substitution sequences of
           krb5_ccname_template can be used here, too, except %d and %P. The directory is created
           as private and owned by the user, with permissions set to 0700.

           Default: /tmp

       krb5_ccname_template (string)
           Location of the user's credential cache. Three credential cache types are currently
           supported: “FILE”, “DIR” and “KEYRING:persistent”. The cache can be specified either
           as TYPE:RESIDUAL, or as an absolute path, which implies the “FILE” type. In the
           template, the following sequences are substituted:

           %u
               login name

           %U
               login UID

           %p
               principal name

           %r
               realm name

           %h
               home directory

           %d
               value of krb5ccache_dir

           %P
               the process ID of the SSSD client

           %%
               a literal '%'

           If the template ends with 'XXXXXX' mkstemp(3) is used to create a unique filename in a
           safe way.

           When using KEYRING types, the only supported mechanism is “KEYRING:persistent:%U”,
           which uses the Linux kernel keyring to store credentials on a per-UID basis. This is
           also the recommended choice, as it is the most secure and predictable method.

           The default value for the credential cache name is sourced from the profile stored in
           the system wide krb5.conf configuration file in the [libdefaults] section. The option
           name is default_ccache_name. See krb5.conf(5)'s PARAMETER EXPANSION paragraph for
           additional information on the expansion format defined by krb5.conf.

           Default: (from libkrb5)

       krb5_auth_timeout (integer)
           Timeout in seconds after an online authentication request or change password request
           is aborted. If possible, the authentication request is continued offline.

           Default: 6

       krb5_validate (boolean)
           Verify with the help of krb5_keytab that the TGT obtained has not been spoofed. The
           keytab is checked for entries sequentially, and the first entry with a matching realm
           is used for validation. If no entry matches the realm, the last entry in the keytab is
           used. This process can be used to validate environments using cross-realm trust by
           placing the appropriate keytab entry as the last entry or the only entry in the keytab
           file.

           Default: false

       krb5_keytab (string)
           The location of the keytab to use when validating credentials obtained from KDCs.

           Default: /etc/krb5.keytab

       krb5_store_password_if_offline (boolean)
           Store the password of the user if the provider is offline and use it to request a TGT
           when the provider comes online again.

           NOTE: this feature is only available on Linux. Passwords stored in this way are kept
           in plaintext in the kernel keyring and are potentially accessible by the root user
           (with difficulty).

           Default: false

       krb5_renewable_lifetime (string)
           Request a renewable ticket with a total lifetime, given as an integer immediately
           followed by a time unit:

           s for seconds

           m for minutes

           h for hours

           d for days.

           If there is no unit given, s is assumed.

           NOTE: It is not possible to mix units. To set the renewable lifetime to one and a half
           hours, use '90m' instead of '1h30m'.

           Default: not set, i.e. the TGT is not renewable

       krb5_lifetime (string)
           Request ticket with a lifetime, given as an integer immediately followed by a time
           unit:

           s for seconds

           m for minutes

           h for hours

           d for days.

           If there is no unit given s is assumed.

           NOTE: It is not possible to mix units. To set the lifetime to one and a half hours
           please use '90m' instead of '1h30m'.

           Default: not set, i.e. the default ticket lifetime configured on the KDC.

       krb5_renew_interval (string)
           The time in seconds between two checks if the TGT should be renewed. TGTs are renewed
           if about half of their lifetime is exceeded, given as an integer immediately followed
           by a time unit:

           s for seconds

           m for minutes

           h for hours

           d for days.

           If there is no unit given, s is assumed.

           NOTE: It is not possible to mix units. To set the renewable lifetime to one and a half
           hours, use '90m' instead of '1h30m'.

           If this option is not set or is 0 the automatic renewal is disabled.

           Default: not set

       krb5_use_fast (string)
           Enables flexible authentication secure tunneling (FAST) for Kerberos
           pre-authentication. The following options are supported:

           never use FAST. This is equivalent to not setting this option at all.

           try to use FAST. If the server does not support FAST, continue the authentication
           without it.

           demand to use FAST. The authentication fails if the server does not require fast.

           Default: not set, i.e. FAST is not used.

           NOTE: a keytab is required to use FAST.

           NOTE: SSSD supports FAST only with MIT Kerberos version 1.8 and later. If SSSD is used
           with an older version of MIT Kerberos, using this option is a configuration error.

       krb5_fast_principal (string)
           Specifies the server principal to use for FAST.

       krb5_canonicalize (boolean)
           Specifies if the host and user principal should be canonicalized. This feature is
           available with MIT Kerberos 1.7 and later versions.

           Default: false

       krb5_use_kdcinfo (boolean)
           Specifies if the SSSD should instruct the Kerberos libraries what realm and which KDCs
           to use. This option is on by default, if you disable it, you need to configure the
           Kerberos library using the krb5.conf(5) configuration file.

           See the sssd_krb5_locator_plugin(8) manual page for more information on the locator
           plugin.

           Default: true

       krb5_use_enterprise_principal (boolean)
           Specifies if the user principal should be treated as enterprise principal. See section
           5 of RFC 6806 for more details about enterprise principals.

           Default: false (AD provider: true)

FAILOVER

       The failover feature allows back ends to automatically switch to a different server if the
       current server fails.

   Failover Syntax
       The list of servers is given as a comma-separated list; any number of spaces is allowed
       around the comma. The servers are listed in order of preference. The list can contain any
       number of servers.

       For each failover-enabled config option, two variants exist: primary and backup. The idea
       is that servers in the primary list are preferred and backup servers are only searched if
       no primary servers can be reached. If a backup server is selected, a timeout of 31 seconds
       is set. After this timeout SSSD will periodically try to reconnect to one of the primary
       servers. If it succeeds, it will replace the current active (backup) server.

   The Failover Mechanism
       The failover mechanism distinguishes between a machine and a service. The back end first
       tries to resolve the hostname of a given machine; if this resolution attempt fails, the
       machine is considered offline. No further attempts are made to connect to this machine for
       any other service. If the resolution attempt succeeds, the back end tries to connect to a
       service on this machine. If the service connection attempt fails, then only this
       particular service is considered offline and the back end automatically switches over to
       the next service. The machine is still considered online and might still be tried for
       another service.

       Further connection attempts are made to machines or services marked as offline after a
       specified period of time; this is currently hard coded to 30 seconds.

       If there are no more machines to try, the back end as a whole switches to offline mode,
       and then attempts to reconnect every 30 seconds.

SERVICE DISCOVERY

       The service discovery feature allows back ends to automatically find the appropriate
       servers to connect to using a special DNS query. This feature is not supported for backup
       servers.

   Configuration
       If no servers are specified, the back end automatically uses service discovery to try to
       find a server. Optionally, the user may choose to use both fixed server addresses and
       service discovery by inserting a special keyword, “_srv_”, in the list of servers. The
       order of preference is maintained. This feature is useful if, for example, the user
       prefers to use service discovery whenever possible, and fall back to a specific server
       when no servers can be discovered using DNS.

   The domain name
       Please refer to the “dns_discovery_domain” parameter in the sssd.conf(5) manual page for
       more details.

   The protocol
       The queries usually specify _tcp as the protocol. Exceptions are documented in respective
       option description.

   See Also
       For more information on the service discovery mechanism, refer to RFC 2782.

EXAMPLE

       The following example assumes that SSSD is correctly configured and FOO is one of the
       domains in the [sssd] section. This example shows only configuration of Kerberos
       authentication; it does not include any identity provider.

               [domain/FOO]
               auth_provider = krb5
               krb5_server = 192.168.1.1
               krb5_realm = EXAMPLE.COM

SEE ALSO

       sssd(8), sssd.conf(5), sssd-ldap(5), sssd-krb5(5), sssd-simple(5), sssd-ipa(5), sssd-
       ad(5), sssd-sudo(5),sss_cache(8), sss_debuglevel(8), sss_groupadd(8), sss_groupdel(8),
       sss_groupshow(8), sss_groupmod(8), sss_useradd(8), sss_userdel(8), sss_usermod(8),
       sss_obfuscate(8), sss_seed(8), sssd_krb5_locator_plugin(8), sss_ssh_authorizedkeys(8),
       sss_ssh_knownhostsproxy(8),pam_sss(8).

AUTHORS

       The SSSD upstream - http://fedorahosted.org/sssd