Provided by: sssd-ldap_2.2.3-3ubuntu0.13_amd64 
NAME
sssd-ldap - SSSD LDAP provider
DESCRIPTION
This manual page describes the configuration of LDAP domains for sssd(8). Refer to the
“FILE FORMAT” section of the sssd.conf(5) manual page for detailed syntax information.
You can configure SSSD to use more than one LDAP domain.
LDAP back end supports id, auth, access and chpass providers. If you want to authenticate
against an LDAP server either TLS/SSL or LDAPS is required. sssd does not support
authentication over an unencrypted channel. If the LDAP server is used only as an identity
provider, an encrypted channel is not needed. Please refer to “ldap_access_filter” config
option for more information about using LDAP as an access provider.
CONFIGURATION OPTIONS
All of the common configuration options that apply to SSSD domains also apply to LDAP
domains. Refer to the “DOMAIN SECTIONS” section of the sssd.conf(5) manual page for full
details. Note that SSSD LDAP mapping attributes are described in the sssd-ldap-
attributes(5) manual page.
ldap_uri, ldap_backup_uri (string)
Specifies the comma-separated list of URIs of the LDAP servers to which SSSD should
connect in the order of preference. Refer to the “FAILOVER” section for more
information on failover and server redundancy. If neither option is specified, service
discovery is enabled. For more information, refer to the “SERVICE DISCOVERY” section.
The format of the URI must match the format defined in RFC 2732:
ldap[s]://<host>[:port]
For explicit IPv6 addresses, <host> must be enclosed in brackets []
example: ldap://[fc00::126:25]:389
ldap_chpass_uri, ldap_chpass_backup_uri (string)
Specifies the comma-separated list of URIs of the LDAP servers to which SSSD should
connect in the order of preference to change the password of a user. Refer to the
“FAILOVER” section for more information on failover and server redundancy.
To enable service discovery ldap_chpass_dns_service_name must be set.
Default: empty, i.e. ldap_uri is used.
ldap_search_base (string)
The default base DN to use for performing LDAP user operations.
Starting with SSSD 1.7.0, SSSD supports multiple search bases using the syntax:
search_base[?scope?[filter][?search_base?scope?[filter]]*]
The scope can be one of "base", "onelevel" or "subtree".
The filter must be a valid LDAP search filter as specified by
http://www.ietf.org/rfc/rfc2254.txt
Examples:
ldap_search_base = dc=example,dc=com (which is equivalent to) ldap_search_base =
dc=example,dc=com?subtree?
ldap_search_base =
cn=host_specific,dc=example,dc=com?subtree?(host=thishost)?dc=example.com?subtree?
Note: It is unsupported to have multiple search bases which reference
identically-named objects (for example, groups with the same name in two different
search bases). This will lead to unpredictable behavior on client machines.
Default: If not set, the value of the defaultNamingContext or namingContexts attribute
from the RootDSE of the LDAP server is used. If defaultNamingContext does not exist or
has an empty value namingContexts is used. The namingContexts attribute must have a
single value with the DN of the search base of the LDAP server to make this work.
Multiple values are are not supported.
ldap_schema (string)
Specifies the Schema Type in use on the target LDAP server. Depending on the selected
schema, the default attribute names retrieved from the servers may vary. The way that
some attributes are handled may also differ.
Four schema types are currently supported:
• rfc2307
• rfc2307bis
• IPA
• AD
The main difference between these schema types is how group memberships are recorded
in the server. With rfc2307, group members are listed by name in the memberUid
attribute. With rfc2307bis and IPA, group members are listed by DN and stored in the
member attribute. The AD schema type sets the attributes to correspond with Active
Directory 2008r2 values.
Default: rfc2307
ldap_pwmodify_mode (string)
Specify the operation that is used to modify user password.
Two modes are currently supported:
• exop - Password Modify Extended Operation (RFC 3062)
• ldap_modify - Direct modification of userPassword (not recommended).
Note: First, a new connection is established to verify current password by binding as
the user that requested password change. If successful, this connection is used to
change the password therefore the user must have write access to userPassword
attribute.
Default: exop
ldap_default_bind_dn (string)
The default bind DN to use for performing LDAP operations.
ldap_default_authtok_type (string)
The type of the authentication token of the default bind DN.
The two mechanisms currently supported are:
password
obfuscated_password
Default: password
ldap_default_authtok (string)
The authentication token of the default bind DN. Only clear text passwords are
currently supported.
ldap_force_upper_case_realm (boolean)
Some directory servers, for example Active Directory, might deliver the realm part of
the UPN in lower case, which might cause the authentication to fail. Set this option
to a non-zero value if you want to use an upper-case realm.
Default: false
ldap_enumeration_refresh_timeout (integer)
Specifies how many seconds SSSD has to wait before refreshing its cache of enumerated
records.
Default: 300
ldap_purge_cache_timeout (integer)
Determine how often to check the cache for inactive entries (such as groups with no
members and users who have never logged in) and remove them to save space.
Setting this option to zero will disable the cache cleanup operation. Please note that
if enumeration is enabled, the cleanup task is required in order to detect entries
removed from the server and can't be disabled. By default, the cleanup task will run
every 3 hours with enumeration enabled.
Default: 0 (disabled)
ldap_group_nesting_level (integer)
If ldap_schema is set to a schema format that supports nested groups (e.g.
RFC2307bis), then this option controls how many levels of nesting SSSD will follow.
This option has no effect on the RFC2307 schema.
Note: This option specifies the guaranteed level of nested groups to be processed for
any lookup. However, nested groups beyond this limit may be returned if previous
lookups already resolved the deeper nesting levels. Also, subsequent lookups for other
groups may enlarge the result set for original lookup if re-queried.
If ldap_group_nesting_level is set to 0 then no nested groups are processed at all.
However, when connected to Active-Directory Server 2008 and later using
“id_provider=ad” it is furthermore required to disable usage of Token-Groups by
setting ldap_use_tokengroups to false in order to restrict group nesting.
Default: 2
ldap_use_tokengroups
This options enables or disables use of Token-Groups attribute when performing
initgroup for users from Active Directory Server 2008 and later.
Default: True for AD and IPA otherwise False.
ldap_host_search_base (string)
Optional. Use the given string as search base for host objects.
See “ldap_search_base” for information about configuring multiple search bases.
Default: the value of ldap_search_base
ldap_service_search_base (string)
An optional base DN, search scope and LDAP filter to restrict LDAP searches for this
attribute type.
syntax:
search_base[?scope?[filter][?search_base?scope?[filter]]*]
The scope can be one of "base", "onelevel" or "subtree". The scope functions as
specified in section 4.5.1.2 of http://tools.ietf.org/html/rfc4511
The filter must be a valid LDAP search filter as specified by
http://www.ietf.org/rfc/rfc2254.txt
For examples of this syntax, please refer to the “ldap_search_base” examples section.
Default: the value of ldap_search_base
Please note that specifying scope or filter is not supported for searches against an
Active Directory Server that might yield a large number of results and trigger the
Range Retrieval extension in the response.
ldap_search_timeout (integer)
Specifies the timeout (in seconds) that ldap searches are allowed to run before they
are cancelled and cached results are returned (and offline mode is entered)
Note: this option is subject to change in future versions of the SSSD. It will likely
be replaced at some point by a series of timeouts for specific lookup types.
Default: 6
ldap_enumeration_search_timeout (integer)
Specifies the timeout (in seconds) that ldap searches for user and group enumerations
are allowed to run before they are cancelled and cached results are returned (and
offline mode is entered)
Default: 60
ldap_network_timeout (integer)
Specifies the timeout (in seconds) after which the poll(2)/select(2) following a
connect(2) returns in case of no activity.
Default: 6
ldap_opt_timeout (integer)
Specifies a timeout (in seconds) after which calls to synchronous LDAP APIs will abort
if no response is received. Also controls the timeout when communicating with the KDC
in case of SASL bind, the timeout of an LDAP bind operation, password change extended
operation and the StartTLS operation.
Default: 8
ldap_connection_expire_timeout (integer)
Specifies a timeout (in seconds) that a connection to an LDAP server will be
maintained. After this time, the connection will be re-established. If used in
parallel with SASL/GSSAPI, the sooner of the two values (this value vs. the TGT
lifetime) will be used.
Default: 900 (15 minutes)
ldap_page_size (integer)
Specify the number of records to retrieve from LDAP in a single request. Some LDAP
servers enforce a maximum limit per-request.
Default: 1000
ldap_disable_paging (boolean)
Disable the LDAP paging control. This option should be used if the LDAP server reports
that it supports the LDAP paging control in its RootDSE but it is not enabled or does
not behave properly.
Example: OpenLDAP servers with the paging control module installed on the server but
not enabled will report it in the RootDSE but be unable to use it.
Example: 389 DS has a bug where it can only support a one paging control at a time on
a single connection. On busy clients, this can result in some requests being denied.
Default: False
ldap_disable_range_retrieval (boolean)
Disable Active Directory range retrieval.
Active Directory limits the number of members to be retrieved in a single lookup using
the MaxValRange policy (which defaults to 1500 members). If a group contains more
members, the reply would include an AD-specific range extension. This option disables
parsing of the range extension, therefore large groups will appear as having no
members.
Default: False
ldap_sasl_minssf (integer)
When communicating with an LDAP server using SASL, specify the minimum security level
necessary to establish the connection. The values of this option are defined by
OpenLDAP.
Default: Use the system default (usually specified by ldap.conf)
ldap_sasl_maxssf (integer)
When communicating with an LDAP server using SASL, specify the maximal security level
necessary to establish the connection. The values of this option are defined by
OpenLDAP.
Default: Use the system default (usually specified by ldap.conf)
ldap_deref_threshold (integer)
Specify the number of group members that must be missing from the internal cache in
order to trigger a dereference lookup. If less members are missing, they are looked up
individually.
You can turn off dereference lookups completely by setting the value to 0. Please note
that there are some codepaths in SSSD, like the IPA HBAC provider, that are only
implemented using the dereference call, so even with dereference explicitly disabled,
those parts will still use dereference if the server supports it and advertises the
dereference control in the rootDSE object.
A dereference lookup is a means of fetching all group members in a single LDAP call.
Different LDAP servers may implement different dereference methods. The currently
supported servers are 389/RHDS, OpenLDAP and Active Directory.
Note: If any of the search bases specifies a search filter, then the dereference
lookup performance enhancement will be disabled regardless of this setting.
Default: 10
ldap_tls_reqcert (string)
Specifies what checks to perform on server certificates in a TLS session, if any. It
can be specified as one of the following values:
never = The client will not request or check any server certificate.
allow = The server certificate is requested. If no certificate is provided, the
session proceeds normally. If a bad certificate is provided, it will be ignored and
the session proceeds normally.
try = The server certificate is requested. If no certificate is provided, the session
proceeds normally. If a bad certificate is provided, the session is immediately
terminated.
demand = The server certificate is requested. If no certificate is provided, or a bad
certificate is provided, the session is immediately terminated.
hard = Same as “demand”
Default: hard
ldap_tls_cacert (string)
Specifies the file that contains certificates for all of the Certificate Authorities
that sssd will recognize.
Default: use OpenLDAP defaults, typically in /etc/openldap/ldap.conf
ldap_tls_cacertdir (string)
Specifies the path of a directory that contains Certificate Authority certificates in
separate individual files. Typically the file names need to be the hash of the
certificate followed by '.0'. If available, cacertdir_rehash can be used to create the
correct names.
Default: use OpenLDAP defaults, typically in /etc/openldap/ldap.conf
ldap_tls_cert (string)
Specifies the file that contains the certificate for the client's key.
Default: not set
ldap_tls_key (string)
Specifies the file that contains the client's key.
Default: not set
ldap_tls_cipher_suite (string)
Specifies acceptable cipher suites. Typically this is a colon separated list. See
ldap.conf(5) for format.
Default: use OpenLDAP defaults, typically in /etc/openldap/ldap.conf
ldap_id_use_start_tls (boolean)
Specifies that the id_provider connection must also use tls to protect the channel.
Default: false
ldap_id_mapping (boolean)
Specifies that SSSD should attempt to map user and group IDs from the
ldap_user_objectsid and ldap_group_objectsid attributes instead of relying on
ldap_user_uid_number and ldap_group_gid_number.
Currently this feature supports only ActiveDirectory objectSID mapping.
Default: false
ldap_min_id, ldap_max_id (integer)
In contrast to the SID based ID mapping which is used if ldap_id_mapping is set to
true the allowed ID range for ldap_user_uid_number and ldap_group_gid_number is
unbound. In a setup with sub/trusted-domains this might lead to ID collisions. To
avoid collisions ldap_min_id and ldap_max_id can be set to restrict the allowed range
for the IDs which are read directly from the server. Sub-domains can then pick other
ranges to map IDs.
Default: not set (both options are set to 0)
ldap_sasl_mech (string)
Specify the SASL mechanism to use. Currently only GSSAPI and GSS-SPNEGO are tested and
supported.
If the backend supports sub-domains the value of ldap_sasl_mech is automatically
inherited to the sub-domains. If a different value is needed for a sub-domain it can
be overwritten by setting ldap_sasl_mech for this sub-domain explicitly. Please see
TRUSTED DOMAIN SECTION in sssd.conf(5) for details.
Default: not set
ldap_sasl_authid (string)
Specify the SASL authorization id to use. When GSSAPI/GSS-SPNEGO are used, this
represents the Kerberos principal used for authentication to the directory. This
option can either contain the full principal (for example host/myhost@EXAMPLE.COM) or
just the principal name (for example host/myhost). By default, the value is not set
and the following principals are used:
hostname@REALM
netbiosname$@REALM
host/hostname@REALM
*$@REALM
host/*@REALM
host/*
If none of them are found, the first principal in keytab is returned.
Default: host/hostname@REALM
ldap_sasl_realm (string)
Specify the SASL realm to use. When not specified, this option defaults to the value
of krb5_realm. If the ldap_sasl_authid contains the realm as well, this option is
ignored.
Default: the value of krb5_realm.
ldap_sasl_canonicalize (boolean)
If set to true, the LDAP library would perform a reverse lookup to canonicalize the
host name during a SASL bind.
Default: false;
ldap_krb5_keytab (string)
Specify the keytab to use when using SASL/GSSAPI/GSS-SPNEGO.
Default: System keytab, normally /etc/krb5.keytab
ldap_krb5_init_creds (boolean)
Specifies that the id_provider should init Kerberos credentials (TGT). This action is
performed only if SASL is used and the mechanism selected is GSSAPI or GSS-SPNEGO.
Default: true
ldap_krb5_ticket_lifetime (integer)
Specifies the lifetime in seconds of the TGT if GSSAPI or GSS-SPNEGO is used.
Default: 86400 (24 hours)
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)
Specify the Kerberos REALM (for SASL/GSSAPI/GSS-SPNEGO auth).
Default: System defaults, see /etc/krb5.conf
krb5_canonicalize (boolean)
Specifies if the host principal should be canonicalized when connecting to LDAP
server. This feature is available with MIT Kerberos >= 1.7
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
ldap_pwd_policy (string)
Select the policy to evaluate the password expiration on the client side. The
following values are allowed:
none - No evaluation on the client side. This option cannot disable server-side
password policies.
shadow - Use shadow(5) style attributes to evaluate if the password has expired.
mit_kerberos - Use the attributes used by MIT Kerberos to determine if the password
has expired. Use chpass_provider=krb5 to update these attributes when the password is
changed.
Default: none
Note: if a password policy is configured on server side, it always takes precedence
over policy set with this option.
ldap_referrals (boolean)
Specifies whether automatic referral chasing should be enabled.
Please note that sssd only supports referral chasing when it is compiled with OpenLDAP
version 2.4.13 or higher.
Chasing referrals may incur a performance penalty in environments that use them
heavily, a notable example is Microsoft Active Directory. If your setup does not in
fact require the use of referrals, setting this option to false might bring a
noticeable performance improvement.
Default: true
ldap_dns_service_name (string)
Specifies the service name to use when service discovery is enabled.
Default: ldap
ldap_chpass_dns_service_name (string)
Specifies the service name to use to find an LDAP server which allows password changes
when service discovery is enabled.
Default: not set, i.e. service discovery is disabled
ldap_chpass_update_last_change (bool)
Specifies whether to update the ldap_user_shadow_last_change attribute with days since
the Epoch after a password change operation.
Default: False
ldap_access_filter (string)
If using access_provider = ldap and ldap_access_order = filter (default), this option
is mandatory. It specifies an LDAP search filter criteria that must be met for the
user to be granted access on this host. If access_provider = ldap, ldap_access_order =
filter and this option is not set, it will result in all users being denied access.
Use access_provider = permit to change this default behavior. Please note that this
filter is applied on the LDAP user entry only and thus filtering based on nested
groups may not work (e.g. memberOf attribute on AD entries points only to direct
parents). If filtering based on nested groups is required, please see sssd-simple(5).
Example:
access_provider = ldap
ldap_access_filter = (employeeType=admin)
This example means that access to this host is restricted to users whose employeeType
attribute is set to "admin".
Offline caching for this feature is limited to determining whether the user's last
online login was granted access permission. If they were granted access during their
last login, they will continue to be granted access while offline and vice versa.
Default: Empty
ldap_account_expire_policy (string)
With this option a client side evaluation of access control attributes can be enabled.
Please note that it is always recommended to use server side access control, i.e. the
LDAP server should deny the bind request with a suitable error code even if the
password is correct.
The following values are allowed:
shadow: use the value of ldap_user_shadow_expire to determine if the account is
expired.
ad: use the value of the 32bit field ldap_user_ad_user_account_control and allow
access if the second bit is not set. If the attribute is missing access is granted.
Also the expiration time of the account is checked.
rhds, ipa, 389ds: use the value of ldap_ns_account_lock to check if access is allowed
or not.
nds: the values of ldap_user_nds_login_allowed_time_map, ldap_user_nds_login_disabled
and ldap_user_nds_login_expiration_time are used to check if access is allowed. If
both attributes are missing access is granted.
This is an experimental feature, please use https://pagure.io/SSSD/sssd/ to report
any issues.
Please note that the ldap_access_order configuration option must include “expire” in
order for the ldap_account_expire_policy option to work.
Default: Empty
ldap_access_order (string)
Comma separated list of access control options. Allowed values are:
filter: use ldap_access_filter
lockout: use account locking. If set, this option denies access in case that ldap
attribute 'pwdAccountLockedTime' is present and has value of '000001010000Z'. Please
see the option ldap_pwdlockout_dn. Please note that 'access_provider = ldap' must be
set for this feature to work.
Please note that this option is superseded by the “ppolicy” option and might be
removed in a future release.
ppolicy: use account locking. If set, this option denies access in case that ldap
attribute 'pwdAccountLockedTime' is present and has value of '000001010000Z' or
represents any time in the past. The value of the 'pwdAccountLockedTime' attribute
must end with 'Z', which denotes the UTC time zone. Other time zones are not currently
supported and will result in "access-denied" when users attempt to log in. Please see
the option ldap_pwdlockout_dn. Please note that 'access_provider = ldap' must be set
for this feature to work.
expire: use ldap_account_expire_policy
pwd_expire_policy_reject, pwd_expire_policy_warn, pwd_expire_policy_renew: These
options are useful if users are interested in being warned that password is about to
expire and authentication is based on using a different method than passwords - for
example SSH keys.
The difference between these options is the action taken if user password is expired:
pwd_expire_policy_reject - user is denied to log in, pwd_expire_policy_warn - user is
still able to log in, pwd_expire_policy_renew - user is prompted to change his
password immediately.
Note If user password is expired no explicit message is prompted by SSSD.
Please note that 'access_provider = ldap' must be set for this feature to work. Also
'ldap_pwd_policy' must be set to an appropriate password policy.
authorized_service: use the authorizedService attribute to determine access
host: use the host attribute to determine access
rhost: use the rhost attribute to determine whether remote host can access
Please note, rhost field in pam is set by application, it is better to check what the
application sends to pam, before enabling this access control option
Default: filter
Please note that it is a configuration error if a value is used more than once.
ldap_pwdlockout_dn (string)
This option specifies the DN of password policy entry on LDAP server. Please note that
absence of this option in sssd.conf in case of enabled account lockout checking will
yield access denied as ppolicy attributes on LDAP server cannot be checked properly.
Example: cn=ppolicy,ou=policies,dc=example,dc=com
Default: cn=ppolicy,ou=policies,$ldap_search_base
ldap_deref (string)
Specifies how alias dereferencing is done when performing a search. The following
options are allowed:
never: Aliases are never dereferenced.
searching: Aliases are dereferenced in subordinates of the base object, but not in
locating the base object of the search.
finding: Aliases are only dereferenced when locating the base object of the search.
always: Aliases are dereferenced both in searching and in locating the base object of
the search.
Default: Empty (this is handled as never by the LDAP client libraries)
ldap_rfc2307_fallback_to_local_users (boolean)
Allows to retain local users as members of an LDAP group for servers that use the
RFC2307 schema.
In some environments where the RFC2307 schema is used, local users are made members of
LDAP groups by adding their names to the memberUid attribute. The self-consistency of
the domain is compromised when this is done, so SSSD would normally remove the
"missing" users from the cached group memberships as soon as nsswitch tries to fetch
information about the user via getpw*() or initgroups() calls.
This option falls back to checking if local users are referenced, and caches them so
that later initgroups() calls will augment the local users with the additional LDAP
groups.
Default: false
wildcard_limit (integer)
Specifies an upper limit on the number of entries that are downloaded during a
wildcard lookup.
At the moment, only the InfoPipe responder supports wildcard lookups.
Default: 1000 (often the size of one page)
SUDO OPTIONS
The detailed instructions for configuration of sudo_provider are in the manual page sssd-
sudo(5).
ldap_sudo_full_refresh_interval (integer)
How many seconds SSSD will wait between executing a full refresh of sudo rules (which
downloads all rules that are stored on the server).
The value must be greater than ldap_sudo_smart_refresh_interval
Default: 21600 (6 hours)
ldap_sudo_smart_refresh_interval (integer)
How many seconds SSSD has to wait before executing a smart refresh of sudo rules
(which downloads all rules that have USN higher than the highest server USN value that
is currently known by SSSD).
If USN attributes are not supported by the server, the modifyTimestamp attribute is
used instead.
Note: the highest USN value can be updated by three tasks: 1) By sudo full and smart
refresh (if updated rules are found), 2) by enumeration of users and groups (if
enabled and updated users or groups are found) and 3) by reconnecting to the server
(by default every 15 minutes, see ldap_connection_expire_timeout).
Default: 900 (15 minutes)
ldap_sudo_use_host_filter (boolean)
If true, SSSD will download only rules that are applicable to this machine (using the
IPv4 or IPv6 host/network addresses and hostnames).
Default: true
ldap_sudo_hostnames (string)
Space separated list of hostnames or fully qualified domain names that should be used
to filter the rules.
If this option is empty, SSSD will try to discover the hostname and the fully
qualified domain name automatically.
If ldap_sudo_use_host_filter is false then this option has no effect.
Default: not specified
ldap_sudo_ip (string)
Space separated list of IPv4 or IPv6 host/network addresses that should be used to
filter the rules.
If this option is empty, SSSD will try to discover the addresses automatically.
If ldap_sudo_use_host_filter is false then this option has no effect.
Default: not specified
ldap_sudo_include_netgroups (boolean)
If true then SSSD will download every rule that contains a netgroup in sudoHost
attribute.
If ldap_sudo_use_host_filter is false then this option has no effect.
Default: true
ldap_sudo_include_regexp (boolean)
If true then SSSD will download every rule that contains a wildcard in sudoHost
attribute.
If ldap_sudo_use_host_filter is false then this option has no effect.
Note
Using wildcard is an operation that is very costly to evaluate on the LDAP server
side!
Default: false
This manual page only describes attribute name mapping. For detailed explanation of sudo
related attribute semantics, see sudoers.ldap(5)
AUTOFS OPTIONS
Some of the defaults for the parameters below are dependent on the LDAP schema.
ldap_autofs_map_master_name (string)
The name of the automount master map in LDAP.
Default: auto.master
ldap_autofs_map_object_class (string)
The object class of an automount map entry in LDAP.
Default: nisMap (rfc2307, autofs_provider=ad), otherwise automountMap
ldap_autofs_map_name (string)
The name of an automount map entry in LDAP.
Default: nisMapName (rfc2307, autofs_provider=ad), otherwise automountMapName
ldap_autofs_entry_object_class (string)
The object class of an automount entry in LDAP. The entry usually corresponds to a
mount point.
Default: nisObject (rfc2307, autofs_provider=ad), otherwise automount
ldap_autofs_entry_key (string)
The key of an automount entry in LDAP. The entry usually corresponds to a mount point.
Default: cn (rfc2307, autofs_provider=ad), otherwise automountKey
ldap_autofs_entry_value (string)
The key of an automount entry in LDAP. The entry usually corresponds to a mount point.
Default: nisMapEntry (rfc2307, autofs_provider=ad), otherwise automountInformation
Please note that the automounter only reads the master map on startup, so if any
autofs-related changes are made to the sssd.conf, you typically also need to restart the
automounter daemon after restarting the SSSD.
ADVANCED OPTIONS
These options are supported by LDAP domains, but they should be used with caution. Please
include them in your configuration only if you know what you are doing.
ldap_netgroup_search_base (string)
An optional base DN, search scope and LDAP filter to restrict LDAP searches for this
attribute type.
syntax:
search_base[?scope?[filter][?search_base?scope?[filter]]*]
The scope can be one of "base", "onelevel" or "subtree". The scope functions as
specified in section 4.5.1.2 of http://tools.ietf.org/html/rfc4511
The filter must be a valid LDAP search filter as specified by
http://www.ietf.org/rfc/rfc2254.txt
For examples of this syntax, please refer to the “ldap_search_base” examples section.
Default: the value of ldap_search_base
Please note that specifying scope or filter is not supported for searches against an
Active Directory Server that might yield a large number of results and trigger the
Range Retrieval extension in the response.
ldap_user_search_base (string)
An optional base DN, search scope and LDAP filter to restrict LDAP searches for this
attribute type.
syntax:
search_base[?scope?[filter][?search_base?scope?[filter]]*]
The scope can be one of "base", "onelevel" or "subtree". The scope functions as
specified in section 4.5.1.2 of http://tools.ietf.org/html/rfc4511
The filter must be a valid LDAP search filter as specified by
http://www.ietf.org/rfc/rfc2254.txt
For examples of this syntax, please refer to the “ldap_search_base” examples section.
Default: the value of ldap_search_base
Please note that specifying scope or filter is not supported for searches against an
Active Directory Server that might yield a large number of results and trigger the
Range Retrieval extension in the response.
ldap_group_search_base (string)
An optional base DN, search scope and LDAP filter to restrict LDAP searches for this
attribute type.
syntax:
search_base[?scope?[filter][?search_base?scope?[filter]]*]
The scope can be one of "base", "onelevel" or "subtree". The scope functions as
specified in section 4.5.1.2 of http://tools.ietf.org/html/rfc4511
The filter must be a valid LDAP search filter as specified by
http://www.ietf.org/rfc/rfc2254.txt
For examples of this syntax, please refer to the “ldap_search_base” examples section.
Default: the value of ldap_search_base
Please note that specifying scope or filter is not supported for searches against an
Active Directory Server that might yield a large number of results and trigger the
Range Retrieval extension in the response.
Note
If the option “ldap_use_tokengroups” is enabled, the searches against Active Directory
will not be restricted and return all groups memberships, even with no GID mapping. It
is recommended to disable this feature, if group names are not being displayed
correctly.
ldap_sudo_search_base (string)
An optional base DN, search scope and LDAP filter to restrict LDAP searches for this
attribute type.
syntax:
search_base[?scope?[filter][?search_base?scope?[filter]]*]
The scope can be one of "base", "onelevel" or "subtree". The scope functions as
specified in section 4.5.1.2 of http://tools.ietf.org/html/rfc4511
The filter must be a valid LDAP search filter as specified by
http://www.ietf.org/rfc/rfc2254.txt
For examples of this syntax, please refer to the “ldap_search_base” examples section.
Default: the value of ldap_search_base
Please note that specifying scope or filter is not supported for searches against an
Active Directory Server that might yield a large number of results and trigger the
Range Retrieval extension in the response.
ldap_autofs_search_base (string)
An optional base DN, search scope and LDAP filter to restrict LDAP searches for this
attribute type.
syntax:
search_base[?scope?[filter][?search_base?scope?[filter]]*]
The scope can be one of "base", "onelevel" or "subtree". The scope functions as
specified in section 4.5.1.2 of http://tools.ietf.org/html/rfc4511
The filter must be a valid LDAP search filter as specified by
http://www.ietf.org/rfc/rfc2254.txt
For examples of this syntax, please refer to the “ldap_search_base” examples section.
Default: the value of ldap_search_base
Please note that specifying scope or filter is not supported for searches against an
Active Directory Server that might yield a large number of results and trigger the
Range Retrieval extension in the response.
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.
Failover time outs and tuning
Resolving a server to connect to can be as simple as running a single DNS query or can
involve several steps, such as finding the correct site or trying out multiple host names
in case some of the configured servers are not reachable. The more complex scenarios can
take some time and SSSD needs to balance between providing enough time to finish the
resolution process but on the other hand, not trying for too long before falling back to
offline mode. If the SSSD debug logs show that the server resolution is timing out before
a live server is contacted, you can consider changing the time outs.
This section lists the available tunables. Please refer to their description in the
sssd.conf(5), manual page.
dns_resolver_server_timeout
Time in milliseconds that sets how long would SSSD talk to a single DNS server before
trying next one.
Default: 1000
dns_resolver_op_timeout
Time in seconds to tell how long would SSSD try to resolve single DNS query (e.g.
resolution of a hostname or an SRV record) before trying the next hostname or
discovery domain.
Default: 2
dns_resolver_timeout
How long would SSSD try to resolve a failover service. This service resolution
internally might include several steps, such as resolving DNS SRV queries or locating
the site.
Default: 4
For LDAP-based providers, the resolve operation is performed as part of an LDAP connection
operation. Therefore, also the “ldap_opt_timeout>” timeout should be set to a larger value
than “dns_resolver_timeout” which in turn should be set to a larger value than
“dns_resolver_op_timeout” which should be larger than “dns_resolver_server_timeout”.
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.
ID MAPPING
The ID-mapping feature allows SSSD to act as a client of Active Directory without
requiring administrators to extend user attributes to support POSIX attributes for user
and group identifiers.
NOTE: When ID-mapping is enabled, the uidNumber and gidNumber attributes are ignored. This
is to avoid the possibility of conflicts between automatically-assigned and
manually-assigned values. If you need to use manually-assigned values, ALL values must be
manually-assigned.
Please note that changing the ID mapping related configuration options will cause user and
group IDs to change. At the moment, SSSD does not support changing IDs, so the SSSD
database must be removed. Because cached passwords are also stored in the database,
removing the database should only be performed while the authentication servers are
reachable, otherwise users might get locked out. In order to cache the password, an
authentication must be performed. It is not sufficient to use sss_cache(8) to remove the
database, rather the process consists of:
• Making sure the remote servers are reachable
• Stopping the SSSD service
• Removing the database
• Starting the SSSD service
Moreover, as the change of IDs might necessitate the adjustment of other system properties
such as file and directory ownership, it's advisable to plan ahead and test the ID mapping
configuration thoroughly.
Mapping Algorithm
Active Directory provides an objectSID for every user and group object in the directory.
This objectSID can be broken up into components that represent the Active Directory domain
identity and the relative identifier (RID) of the user or group object.
The SSSD ID-mapping algorithm takes a range of available UIDs and divides it into
equally-sized component sections - called "slices"-. Each slice represents the space
available to an Active Directory domain.
When a user or group entry for a particular domain is encountered for the first time, the
SSSD allocates one of the available slices for that domain. In order to make this
slice-assignment repeatable on different client machines, we select the slice based on the
following algorithm:
The SID string is passed through the murmurhash3 algorithm to convert it to a 32-bit
hashed value. We then take the modulus of this value with the total number of available
slices to pick the slice.
NOTE: It is possible to encounter collisions in the hash and subsequent modulus. In these
situations, we will select the next available slice, but it may not be possible to
reproduce the same exact set of slices on other machines (since the order that they are
encountered will determine their slice). In this situation, it is recommended to either
switch to using explicit POSIX attributes in Active Directory (disabling ID-mapping) or
configure a default domain to guarantee that at least one is always consistent. See
“Configuration” for details.
Configuration
Minimum configuration (in the “[domain/DOMAINNAME]” section):
ldap_id_mapping = True
ldap_schema = ad
The default configuration results in configuring 10,000 slices, each capable of holding up
to 200,000 IDs, starting from 200,000 and going up to 2,000,200,000. This should be
sufficient for most deployments.
Advanced Configuration
ldap_idmap_range_min (integer)
Specifies the lower bound of the range of POSIX IDs to use for mapping Active
Directory user and group SIDs.
NOTE: This option is different from “min_id” in that “min_id” acts to filter the
output of requests to this domain, whereas this option controls the range of ID
assignment. This is a subtle distinction, but the good general advice would be to
have “min_id” be less-than or equal to “ldap_idmap_range_min”
Default: 200000
ldap_idmap_range_max (integer)
Specifies the upper bound of the range of POSIX IDs to use for mapping Active
Directory user and group SIDs.
NOTE: This option is different from “max_id” in that “max_id” acts to filter the
output of requests to this domain, whereas this option controls the range of ID
assignment. This is a subtle distinction, but the good general advice would be to
have “max_id” be greater-than or equal to “ldap_idmap_range_max”
Default: 2000200000
ldap_idmap_range_size (integer)
Specifies the number of IDs available for each slice. If the range size does not
divide evenly into the min and max values, it will create as many complete slices
as it can.
NOTE: The value of this option must be at least as large as the highest user RID
planned for use on the Active Directory server. User lookups and login will fail
for any user whose RID is greater than this value.
For example, if your most recently-added Active Directory user has
objectSid=S-1-5-21-2153326666-2176343378-3404031434-1107, “ldap_idmap_range_size”
must be at least 1108 as range size is equal to maximal SID minus minimal SID plus
one (e.g. 1108 = 1107 - 0 + 1).
It is important to plan ahead for future expansion, as changing this value will
result in changing all of the ID mappings on the system, leading to users with
different local IDs than they previously had.
Default: 200000
ldap_idmap_default_domain_sid (string)
Specify the domain SID of the default domain. This will guarantee that this domain
will always be assigned to slice zero in the ID map, bypassing the murmurhash
algorithm described above.
Default: not set
ldap_idmap_default_domain (string)
Specify the name of the default domain.
Default: not set
ldap_idmap_autorid_compat (boolean)
Changes the behavior of the ID-mapping algorithm to behave more similarly to
winbind's “idmap_autorid” algorithm.
When this option is configured, domains will be allocated starting with slice zero
and increasing monatomically with each additional domain.
NOTE: This algorithm is non-deterministic (it depends on the order that users and
groups are requested). If this mode is required for compatibility with machines
running winbind, it is recommended to also use the “ldap_idmap_default_domain_sid”
option to guarantee that at least one domain is consistently allocated to slice
zero.
Default: False
ldap_idmap_helper_table_size (integer)
Maximal number of secondary slices that is tried when performing mapping from UNIX
id to SID.
Note: Additional secondary slices might be generated when SID is being mapped to
UNIX id and RID part of SID is out of range for secondary slices generated so far.
If value of ldap_idmap_helper_table_size is equal to 0 then no additional
secondary slices are generated.
Default: 10
Well-Known SIDs
SSSD supports to look up the names of Well-Known SIDs, i.e. SIDs with a special hardcoded
meaning. Since the generic users and groups related to those Well-Known SIDs have no
equivalent in a Linux/UNIX environment no POSIX IDs are available for those objects.
The SID name space is organized in authorities which can be seen as different domains. The
authorities for the Well-Known SIDs are
• Null Authority
• World Authority
• Local Authority
• Creator Authority
• NT Authority
• Built-in
The capitalized version of these names are used as domain names when returning the fully
qualified name of a Well-Known SID.
Since some utilities allow to modify SID based access control information with the help of
a name instead of using the SID directly SSSD supports to look up the SID by the name as
well. To avoid collisions only the fully qualified names can be used to look up Well-Known
SIDs. As a result the domain names “NULL AUTHORITY”, “WORLD AUTHORITY”, “ LOCAL
AUTHORITY”, “CREATOR AUTHORITY”, “NT AUTHORITY” and “BUILTIN” should not be used as domain
names in sssd.conf.
EXAMPLE
The following example assumes that SSSD is correctly configured and LDAP is set to one of
the domains in the [domains] section.
[domain/LDAP]
id_provider = ldap
auth_provider = ldap
ldap_uri = ldap://ldap.mydomain.org
ldap_search_base = dc=mydomain,dc=org
ldap_tls_reqcert = demand
cache_credentials = true
LDAP ACCESS FILTER EXAMPLE
The following example assumes that SSSD is correctly configured and to use the
ldap_access_order=lockout.
[domain/LDAP]
id_provider = ldap
auth_provider = ldap
access_provider = ldap
ldap_access_order = lockout
ldap_pwdlockout_dn = cn=ppolicy,ou=policies,dc=mydomain,dc=org
ldap_uri = ldap://ldap.mydomain.org
ldap_search_base = dc=mydomain,dc=org
ldap_tls_reqcert = demand
cache_credentials = true
NOTES
The descriptions of some of the configuration options in this manual page are based on the
ldap.conf(5) manual page from the OpenLDAP 2.4 distribution.
SEE ALSO
sssd(8), sssd.conf(5), sssd-ldap(5), sssd-krb5(5), sssd-simple(5), sssd-ipa(5), sssd-
ad(5), sssd-files(5), sssd-sudo(5), sssd-session-recording(5), sss_cache(8),
sss_debuglevel(8), sss_obfuscate(8), sss_seed(8), sssd_krb5_locator_plugin(8),
sss_ssh_authorizedkeys(8), sss_ssh_knownhostsproxy(8), sssd-ifp(5), pam_sss(8).
sss_rpcidmapd(5) sssd-systemtap(5)
AUTHORS
The SSSD upstream - https://pagure.io/SSSD/sssd/