# $OpenLDAP$
# Copyright 2005-2021 The OpenLDAP Foundation, All Rights Reserved.
# COPYING RESTRICTIONS APPLY, see COPYRIGHT.
H1: Configuring slapd
Once the software has been built and installed, you are ready
to configure {{slapd}}(8) for use at your site.
OpenLDAP 2.3 and later have transitioned to using a dynamic runtime
configuration engine, {{slapd-config}}(5). {{slapd-config}}(5)
* is fully LDAP-enabled
* is managed using the standard LDAP operations
* stores its configuration data in an {{TERM:LDIF}} database, generally
in the {{F:/usr/local/etc/openldap/slapd.d}} directory.
* allows all of slapd's configuration options to be changed on the fly,
generally without requiring a server restart for the changes
to take effect.
This chapter describes the general format of the {{slapd-config}}(5)
configuration system, followed by a detailed description of commonly used
settings.
The older style {{slapd.conf}}(5) file is still supported, but its use
is deprecated and support for it will be withdrawn in a future OpenLDAP
release. Configuring {{slapd}}(8) via {{slapd.conf}}(5) is described in
the next chapter.
Refer to {{slapd}}(8) for information on how to have slapd automatically
convert from {{slapd.conf}}(5) to {{slapd-config}}(5).
Note: Although the {{slapd-config}}(5) system stores its configuration
as (text-based) LDIF files, you should {{1:never}} edit any of
the LDIF files directly. Configuration changes should be performed via LDAP
operations, e.g. {{ldapadd}}(1), {{ldapdelete}}(1), or {{ldapmodify}}(1).
For offline modifications (when the server is not running), use {{slapadd}}(8)
and {{slapmodify}}(8).
Note: You will need to continue to use the older {{slapd.conf}}(5)
configuration system if your OpenLDAP installation requires the use of one
or more backends or overlays that have not been updated to use the
{{slapd-config}}(5) system. As of OpenLDAP 2.4.33, all of the official
backends have been updated. There may be additional contributed or experimental
overlays that also have not been updated.
H2: Configuration Layout
The slapd configuration is stored as a special LDAP directory with
a predefined schema and DIT. There are specific objectClasses used to
carry global configuration options, schema definitions, backend and
database definitions, and assorted other items. A sample config tree
is shown in Figure 5.1.
!import "config_dit.png"; align="center"; title="Sample configuration tree"
FT[align="Center"] Figure 5.1: Sample configuration tree.
Other objects may be part of the configuration but were omitted from
the illustration for clarity.
The {{slapd-config}} configuration tree has a very specific structure. The
root of the tree is named {{EX:cn=config}} and contains global configuration
settings. Additional settings are contained in separate child entries:
* Dynamically loaded modules
.. These may only be used if the {{EX:--enable-modules}} option was
used to configure the software.
* Schema definitions
.. The {{EX:cn=schema,cn=config}} entry contains the system schema (all
the schema that is hard-coded in slapd).
.. Child entries of {{EX:cn=schema,cn=config}} contain user schema as
loaded from config files or added at runtime.
* Backend-specific configuration
* Database-specific configuration
.. Overlays are defined in children of the Database entry.
.. Databases and Overlays may also have other miscellaneous children.
The usual rules for LDIF files apply to the configuration information:
Comment lines beginning with a '{{EX:#}}' character
are ignored. If a line begins with a single space, it is considered a
continuation of the previous line (even if the previous line is a
comment) and the single leading space is removed. Entries are separated by blank lines.
The general layout of the config LDIF is as follows:
> # global configuration settings
> dn: cn=config
> objectClass: olcGlobal
> cn: config
> <global config settings>
>
> # schema definitions
> dn: cn=schema,cn=config
> objectClass: olcSchemaConfig
> cn: schema
> <system schema>
>
> dn: cn={X}core,cn=schema,cn=config
> objectClass: olcSchemaConfig
> cn: {X}core
> <core schema>
>
> # additional user-specified schema
> ...
>
> # backend definitions
> dn: olcBackend=<typeA>,cn=config
> objectClass: olcBackendConfig
> olcBackend: <typeA>
> <backend-specific settings>
>
> # database definitions
> dn: olcDatabase={X}<typeA>,cn=config
> objectClass: olcDatabaseConfig
> olcDatabase: {X}<typeA>
> <database-specific settings>
>
> # subsequent definitions and settings
> ...
Some of the entries listed above have a numeric index {{EX:"{X}"}} in
their names. While most configuration settings have an inherent ordering
dependency (i.e., one setting must take effect before a subsequent one
may be set), LDAP databases are inherently unordered. The numeric index
is used to enforce a consistent ordering in the configuration database,
so that all ordering dependencies are preserved. In most cases the index
does not have to be provided; it will be automatically generated based
on the order in which entries are created.
Configuration directives are specified as values of individual
attributes.
Most of the attributes and objectClasses used in the slapd
configuration have a prefix of {{EX:"olc"}} (OpenLDAP Configuration)
in their names. Generally there is a one-to-one correspondence
between the attributes and the old-style {{EX:slapd.conf}} configuration
keywords, using the keyword as the attribute name, with the "olc"
prefix attached.
A configuration directive may take arguments. If so, the arguments are
separated by whitespace. If an argument contains whitespace,
the argument should be enclosed in double quotes {{EX:"like this"}}.
In the descriptions that follow, arguments that should be replaced
by actual text are shown in brackets {{EX:<>}}.
The distribution contains an example configuration file that will
be installed in the {{F: /usr/local/etc/openldap}} directory.
A number of files containing schema definitions (attribute types
and object classes) are also provided in the
{{F: /usr/local/etc/openldap/schema}} directory.
H2: Configuration Directives
This section details commonly used configuration directives. For
a complete list, see the {{slapd-config}}(5) manual page. This section
will treat the configuration directives in a top-down order, starting
with the global directives in the {{EX:cn=config}} entry. Each
directive will be described along with its default value (if any) and
an example of its use.
H3: cn=config
Directives contained in this entry generally apply to the server as a whole.
Most of them are system or connection oriented, not database related. This
entry must have the {{EX:olcGlobal}} objectClass.
H4: olcIdleTimeout: <integer>
Specify the number of seconds to wait before forcibly closing
an idle client connection. A value of 0, the default,
disables this feature.
H4: olcLogLevel: <level>
This directive specifies the level at which log statements
and operation statistics should be sent to syslog (currently logged to
the {{syslogd}}(8) {{EX:LOG_LOCAL4}} facility). You must have
configured OpenLDAP {{EX:--enable-debug}} (the default) for this
to work, except for the two statistics levels, which are always
enabled. Log levels may be specified as integers or by keyword.
Multiple log levels may be used and the levels are additive.
The possible values for <level> are:
!block table; colaligns="RL"; align=Center; \
title="Table 5.1: Logging Levels"
Level Keyword Description
-1 any enable all debugging
0 no debugging
1 (0x1 trace) trace function calls
2 (0x2 packets) debug packet handling
4 (0x4 args) heavy trace debugging
8 (0x8 conns) connection management
16 (0x10 BER) print out packets sent and received
32 (0x20 filter) search filter processing
64 (0x40 config) configuration processing
128 (0x80 ACL) access control list processing
256 (0x100 stats) stats log connections/operations/results
512 (0x200 stats2) stats log entries sent
1024 (0x400 shell) print communication with shell backends
2048 (0x800 parse) print entry parsing debugging
16384 (0x4000 sync) syncrepl consumer processing
32768 (0x8000 none) only messages that get logged regardless of configured log level
!endblock
The desired log level can be input as a single integer that
combines the (ORed) desired levels, both in decimal or in hexadecimal
notation, as a list of integers (that are ORed internally), or as a list of the names that are shown between brackets, such that
> olcLogLevel 129
> olcLogLevel 0x81
> olcLogLevel 128 1
> olcLogLevel 0x80 0x1
> olcLogLevel acl trace
are equivalent.
\Examples:
E: olcLogLevel -1
This will enable all log levels.
E: olcLogLevel conns filter
Just log the connection and search filter processing.
E: olcLogLevel none
Log those messages that are logged regardless of the configured loglevel. This
differs from setting the log level to 0, when no logging occurs. At least the
{{EX:None}} level is required to have high priority messages logged.
\Default:
E: olcLogLevel stats
Basic stats logging is configured by default.
H4: olcReferral <URI>
This directive specifies the referral to pass back when slapd
cannot find a local database to handle a request.
\Example:
> olcReferral: ldap://root.openldap.org
This will refer non-local queries to the global root LDAP server
at the OpenLDAP Project. Smart LDAP clients can re-ask their
query at that server, but note that most of these clients are
only going to know how to handle simple LDAP URLs that
contain a host part and optionally a distinguished name part.
H4: Sample Entry
>dn: cn=config
>objectClass: olcGlobal
>cn: config
>olcIdleTimeout: 30
>olcLogLevel: Stats
>olcReferral: ldap://root.openldap.org
H3: cn=module
If support for dynamically loaded modules was enabled when configuring
slapd, {{EX:cn=module}} entries may be used to specify sets of modules to load.
Module entries must have the {{EX:olcModuleList}} objectClass.
H4: olcModuleLoad: <filename>
Specify the name of a dynamically loadable module to load. The filename
may be an absolute path name or a simple filename. Non-absolute names
are searched for in the directories specified by the {{EX:olcModulePath}}
directive.
H4: olcModulePath: <pathspec>
Specify a list of directories to search for loadable modules. Typically the
path is colon-separated but this depends on the operating system.
H4: Sample Entries
>dn: cn=module{0},cn=config
>objectClass: olcModuleList
>cn: module{0}
>olcModuleLoad: /usr/local/lib/smbk5pwd.la
>
>dn: cn=module{1},cn=config
>objectClass: olcModuleList
>cn: module{1}
>olcModulePath: /usr/local/lib:/usr/local/lib/slapd
>olcModuleLoad: accesslog.la
>olcModuleLoad: pcache.la
H3: cn=schema
The cn=schema entry holds all of the schema definitions that are hard-coded
in slapd. As such, the values in this entry are generated by slapd so no
schema values need to be provided in the config file. The entry must still
be defined though, to serve as a base for the user-defined schema to add
in underneath. Schema entries must have the {{EX:olcSchemaConfig}}
objectClass.
H4: olcAttributeTypes: <{{REF:RFC4512}} Attribute Type Description>
This directive defines an attribute type.
Please see the {{SECT:Schema Specification}} chapter
for information regarding how to use this directive.
H4: olcObjectClasses: <{{REF:RFC4512}} Object Class Description>
This directive defines an object class.
Please see the {{SECT:Schema Specification}} chapter for
information regarding how to use this directive.
H4: Sample Entries
>dn: cn=schema,cn=config
>objectClass: olcSchemaConfig
>cn: schema
>
>dn: cn=test,cn=schema,cn=config
>objectClass: olcSchemaConfig
>cn: test
>olcAttributeTypes: ( 1.1.1
> NAME 'testAttr'
> EQUALITY integerMatch
> SYNTAX 1.3.6.1.4.1.1466.115.121.1.27 )
>olcAttributeTypes: ( 1.1.2 NAME 'testTwo' EQUALITY caseIgnoreMatch
> SUBSTR caseIgnoreSubstringsMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.44 )
>olcObjectClasses: ( 1.1.3 NAME 'testObject'
> MAY ( testAttr $ testTwo ) AUXILIARY )
H3: Backend-specific Directives
Backend directives apply to all database instances of the
same type and, depending on the directive, may be overridden
by database directives. Backend entries must have the
{{EX:olcBackendConfig}} objectClass.
H4: olcBackend: <type>
This directive names a backend-specific configuration entry.
{{EX:<type>}} should be one of the
supported backend types listed in Table 5.2.
!block table; align=Center; coltags="EX,N"; \
title="Table 5.2: Database Backends"
Types Description
asyncmeta Asynchronous Metadirectory backend
config Slapd configuration backend
dnssrv DNS SRV backend
ldap Lightweight Directory Access Protocol (Proxy) backend
ldif Lightweight Data Interchange Format backend
mdb Memory-Mapped DB backend
meta Metadirectory backend
monitor Monitor backend
ndb MySQL NDB backend
null Null backend
passwd Provides read-only access to {{passwd}}(5)
perl Perl Programmable backend
relay Relay backend
sock Socket backend
sql SQL Programmable backend
wt WiredTiger backend
!endblock
\Example:
> olcBackend: mdb
This marks the beginning of a new {{TERM:MDB}} backend
definition. At present, only back-mdb implements any options
of this type, so this setting is not needed for any other backends.
H4: Sample Entry
> dn: olcBackend=mdb,cn=config
> objectClass: olcBackendConfig
> olcBackend: mdb
> olcBkMdbIdlExp: 16
H3: Database-specific Directives
Directives in this section are supported by every type of database.
Database entries must have the {{EX:olcDatabaseConfig}} objectClass.
H4: olcDatabase: [{<index>}]<type>
This directive names a specific database instance. The numeric {<index>} may
be provided to distinguish multiple databases of the same type. Usually the
index can be omitted, and slapd will generate it automatically.
{{EX:<type>}} should be one of the
supported backend types listed in Table 5.2 or the {{EX:frontend}} type.
The {{EX:frontend}} is a special database that is used to hold
database-level options that should be applied to all the other
databases. Subsequent database definitions may also override some
frontend settings.
The {{EX:config}} database is also special; both the {{EX:config}} and
the {{EX:frontend}} databases are always created implicitly even if they
are not explicitly configured, and they are created before any other
databases.
\Example:
> olcDatabase: mdb
This marks the beginning of a new {{TERM:MDB}} database instance.
H4: olcAccess: to <what> [ by <who> [<accesslevel>] [<control>] ]+
This directive grants access (specified by <accesslevel>) to a
set of entries and/or attributes (specified by <what>) by one or
more requestors (specified by <who>).
See the {{SECT:Access Control}} section of this guide for basic usage.
!if 0
More detailed discussion of this directive can be found in the
{{SECT:Advanced Access Control}} chapter.
!endif
Note: If no {{EX:olcAccess}} directives are specified, the default
access control policy, {{EX:to * by * read}}, allows all
users (both authenticated and anonymous) read access.
Note: Access controls defined in the frontend are appended to all
other databases' controls.
H4: olcReadonly { TRUE | FALSE }
This directive puts the database into "read-only" mode. Any
attempts to modify the database will return an "unwilling to
perform" error. If set on a consumer, modifications sent by
syncrepl will still occur.
\Default:
> olcReadonly: FALSE
H4: olcRootDN: <DN>
This directive specifies the DN that is not subject to
access control or administrative limit restrictions for
operations on this database. The DN need not refer to
an entry in this database or even in the directory. The
DN may refer to a SASL identity.
Entry-based Example:
> olcRootDN: cn=Manager,dc=example,dc=com
SASL-based Example:
> olcRootDN: uid=root,cn=example.com,cn=digest-md5,cn=auth
See the {{SECT:SASL Authentication}} section for information on
SASL authentication identities.
H4: olcRootPW: <password>
This directive can be used to specify a password for the DN for
the rootdn (when the rootdn is set to a DN within the database).
\Example:
> olcRootPW: secret
It is also permissible to provide a hash of the password in
{{REF:RFC2307}} form. {{slappasswd}}(8) may be used to generate
the password hash.
\Example:
> olcRootPW: {SSHA}ZKKuqbEKJfKSXhUbHG3fG8MDn9j1v4QN
The hash was generated using the command {{EX:slappasswd -s secret}}.
H4: olcSizeLimit: <integer>
This directive specifies the maximum number of entries to return
from a search operation.
\Default:
> olcSizeLimit: 500
See the {{SECT:Limits}} section of this guide and slapd-config(5)
for more details.
H4: olcSuffix: <dn suffix>
This directive specifies the DN suffix of queries that will be
passed to this backend database. Multiple suffix lines can be
given, and usually at least one is required for each database
definition. (Some backend types, such as {{EX:frontend}} and
{{EX:monitor}} use a hard-coded suffix which may not be overridden
in the configuration.)
\Example:
> olcSuffix: dc=example,dc=com
Queries with a DN ending in "dc=example,dc=com"
will be passed to this backend.
Note: When the backend to pass a query to is selected, slapd
looks at the suffix value(s) in each database definition in the
order in which they were configured. Thus, if one database suffix is a
prefix of another, it must appear after it in the configuration.
H4: olcSyncrepl
> olcSyncrepl: rid=<replica ID>
> provider=ldap[s]://<hostname>[:port]
> [type=refreshOnly|refreshAndPersist]
> [interval=dd:hh:mm:ss]
> [retry=[<retry interval> <# of retries>]+]
> searchbase=<base DN>
> [filter=<filter str>]
> [scope=sub|one|base]
> [attrs=<attr list>]
> [attrsonly]
> [sizelimit=<limit>]
> [timelimit=<limit>]
> [schemachecking=on|off]
> [bindmethod=simple|sasl]
> [binddn=<DN>]
> [saslmech=<mech>]
> [authcid=<identity>]
> [authzid=<identity>]
> [credentials=<passwd>]
> [realm=<realm>]
> [secprops=<properties>]
> [starttls=yes|critical]
> [tls_cert=<file>]
> [tls_key=<file>]
> [tls_cacert=<file>]
> [tls_cacertdir=<path>]
> [tls_reqcert=never|allow|try|demand]
> [tls_cipher_suite=<ciphers>]
> [tls_crlcheck=none|peer|all]
> [logbase=<base DN>]
> [logfilter=<filter str>]
> [syncdata=default|accesslog|changelog]
This directive specifies the current database as a consumer of the
provider content by establishing the current {{slapd}}(8) as a
replication consumer site running a syncrepl replication engine.
The provider database is located at the provider site
specified by the {{EX:provider}} parameter. The consumer database is
kept up-to-date with the provider content using the LDAP Content
Synchronization protocol. See {{REF:RFC4533}}
for more information on the protocol.
The {{EX:rid}} parameter is used for identification of the current
{{EX:syncrepl}} directive within the replication consumer server,
where {{EX:<replica ID>}} uniquely identifies the syncrepl specification
described by the current {{EX:syncrepl}} directive. {{EX:<replica ID>}}
is non-negative and is no more than three decimal digits in length.
The {{EX:provider}} parameter specifies the replication provider site
containing the provider content as an LDAP URI. The {{EX:provider}}
parameter specifies a scheme, a host and optionally a port where the
provider slapd instance can be found. Either a domain name or IP
address may be used for <hostname>. Examples are
{{EX:ldap://provider.example.com:389}} or {{EX:ldaps://192.168.1.1:636}}.
If <port> is not given, the standard LDAP port number (389 or 636) is used.
Note that the syncrepl uses a consumer-initiated protocol, and hence its
specification is located on the consumer.
The content of the syncrepl consumer is defined using a search
specification as its result set. The consumer slapd will
send search requests to the provider slapd according to the search
specification. The search specification includes {{EX:searchbase}},
{{EX:scope}}, {{EX:filter}}, {{EX:attrs}}, {{EX:attrsonly}},
{{EX:sizelimit}}, and {{EX:timelimit}} parameters as in the normal
search specification. The {{EX:searchbase}} parameter has no
default value and must always be specified. The {{EX:scope}} defaults
to {{EX:sub}}, the {{EX:filter}} defaults to {{EX:(objectclass=*)}},
{{EX:attrs}} defaults to {{EX:"*,+"}} to replicate all user and operational
attributes, and {{EX:attrsonly}} is unset by default. Both {{EX:sizelimit}}
and {{EX:timelimit}} default to "unlimited", and only positive integers
or "unlimited" may be specified.
The {{TERM[expand]LDAP Sync}} protocol has two operation
types: {{EX:refreshOnly}} and {{EX:refreshAndPersist}}.
The operation type is specified by the {{EX:type}} parameter.
In the {{EX:refreshOnly}} operation, the next synchronization search operation
is periodically rescheduled at an interval time after each
synchronization operation finishes. The interval is specified
by the {{EX:interval}} parameter. It is set to one day by default.
In the {{EX:refreshAndPersist}} operation, a synchronization search
remains persistent in the provider {{slapd}} instance. Further updates to the
provider will generate {{EX:searchResultEntry}} to the consumer slapd
as the search responses to the persistent synchronization search.
If an error occurs during replication, the consumer will attempt to reconnect
according to the retry parameter which is a list of the <retry interval>
and <# of retries> pairs. For example, retry="60 10 300 3" lets the consumer
retry every 60 seconds for the first 10 times and then retry every 300 seconds
for the next three times before stop retrying. + in <# of retries> means
indefinite number of retries until success.
The schema checking can be enforced at the LDAP Sync consumer site
by turning on the {{EX:schemachecking}} parameter.
If it is turned on, every replicated entry will be checked for its
schema as the entry is stored on the consumer.
Every entry in the consumer should contain those attributes
required by the schema definition.
If it is turned off, entries will be stored without checking
schema conformance. The default is off.
The {{EX:binddn}} parameter gives the DN to bind as for the
syncrepl searches to the provider slapd. It should be a DN
which has read access to the replication content in the
provider database.
The {{EX:bindmethod}} is {{EX:simple}} or {{EX:sasl}},
depending on whether simple password-based authentication or
{{TERM:SASL}} authentication is to be used when connecting
to the provider {{slapd}} instance.
Simple authentication should not be used unless adequate data
integrity and confidentiality protections are in place (e.g. TLS
or IPsec). Simple authentication requires specification of {{EX:binddn}}
and {{EX:credentials}} parameters.
SASL authentication is generally recommended. SASL authentication
requires specification of a mechanism using the {{EX:saslmech}} parameter.
Depending on the mechanism, an authentication identity and/or
credentials can be specified using {{EX:authcid}} and {{EX:credentials}},
respectively. The {{EX:authzid}} parameter may be used to specify
an authorization identity.
The {{EX:realm}} parameter specifies a realm which a certain
mechanisms authenticate the identity within. The {{EX:secprops}}
parameter specifies Cyrus SASL security properties.
The {{EX:starttls}} parameter specifies use of the StartTLS extended
operation to establish a TLS session before authenticating to the provider.
If the {{EX:critical}} argument is supplied, the session will be aborted
if the StartTLS request fails. Otherwise the syncrepl session continues
without TLS. The tls_reqcert setting defaults to {{EX:"demand"}} and the
other TLS settings default to the same as the main slapd TLS settings.
Rather than replicating whole entries, the consumer can query logs
of data modifications. This mode of operation is referred to as
{{delta syncrepl}}. In addition to the above parameters, the
{{EX:logbase}} and {{EX:logfilter}} parameters must be set appropriately
for the log that will be used. The {{EX:syncdata}} parameter must
be set to either {{EX:"accesslog"}} if the log conforms to the
{{slapo-accesslog}}(5) log format, or {{EX:"changelog"}} if the log
conforms to the obsolete {{changelog}} format. If the {{EX:syncdata}}
parameter is omitted or set to {{EX:"default"}} then the log
parameters are ignored.
The {{syncrepl}} replication mechanism is supported by the {{mdb}}
backend.
See the {{SECT:LDAP Sync Replication}} chapter of this guide for
more information on how to use this directive.
H4: olcTimeLimit: <integer>
This directive specifies the maximum number of seconds (in real
time) slapd will spend answering a search request. If a
request is not finished in this time, a result indicating an
exceeded timelimit will be returned.
\Default:
> olcTimeLimit: 3600
See the {{SECT:Limits}} section of this guide and slapd-config(5)
for more details.
H4: olcUpdateref: <URL>
This directive is only applicable in a {{replica}} (or {{shadow}})
{{slapd}}(8) instance. It
specifies the URL to return to clients which submit update
requests upon the replica.
If specified multiple times, each {{TERM:URL}} is provided.
\Example:
> olcUpdateref: ldap://provider.example.net
H4: Sample Entries
>dn: olcDatabase=frontend,cn=config
>objectClass: olcDatabaseConfig
>objectClass: olcFrontendConfig
>olcDatabase: frontend
>olcReadOnly: FALSE
>
>dn: olcDatabase=config,cn=config
>objectClass: olcDatabaseConfig
>olcDatabase: config
>olcRootDN: cn=Manager,dc=example,dc=com
H3: MDB Backend Directives
Directives in this category only apply to the {{TERM:MDB}}
database backend. They will apply to all "database mdb"
instances in the configuration. For a complete reference
of MDB backend configuration directives, see {{slapd-mdb}}(5).
H4: olcBkMdbIdlExp <exponent>
Specify a power of 2 for the maximum size of an index slot.
The default is 16, yielding a maximum slot size of 2^16 or 65536.
The specified value must be in the range of 16-31.
This setting helps with the case where certain search filters are
slow to return results due to an index slot having collapsed to a
range value. This occurs when the number of candidate entries that
match the filter for the index slot exceed the configured slot size.
If this setting is decreased on a server with existing {{TERM:MDB}}
databases, each db will immediately need its indices to be rebuilt
while slapd is offline with the "slapindex -q -t" command.
If this setting is increased on a server with existing {{TERM:MDB}}
databases, each db will need its indices rebuilt to take advantage
of the change for indices that have already been converted to ranges.
H3: MDB Database Directives
Directives in this category apply to the {{TERM:MDB}}
database backend.
They are used in an olcDatabase entry in addition to the generic
database directives defined above. For a complete reference
of MDB configuration directives, see {{slapd-mdb}}(5). In
addition to the {{EX:olcDatabaseConfig}} objectClass, MDB
database entries must have the {{EX:olcMdbConfig}} objectClass.
H4: olcDbDirectory: <directory>
This directive specifies the directory where the MDB files
containing the database and associated indices live.
\Default:
> olcDbDirectory: /usr/local/var/openldap-data
H4: olcDbCheckpoint: <kbyte> <min>
This directive specifies the frequency for flushing the database disk
buffers. This directive is only needed if the {{olcDbNoSync}} option is
{{EX:TRUE}}.
The checkpoint will occur if either <kbyte> data has been written or
<min> minutes have passed since the last checkpoint. Both arguments default
to zero, in which case they are ignored. When the <min> argument is
non-zero, an internal task will run every <min> minutes to perform the
checkpoint. Note: currently the _kbyte_ setting is unimplemented.
\Example:
> olcDbCheckpoint: 1024 10
H4: olcDbEnvFlags: {nosync,nometasync,writemap,mapasync,nordahead}
This option specifies flags for finer-grained control of the LMDB library's
operation.
* {{F:nosync}}: This is exactly the same as the dbnosync directive.
* {{F:nometasync}}: Flush the data on a commit, but skip the sync of the meta
page. This mode is slightly faster than doing a full sync, but can
potentially lose the last committed transaction if the operating system
crashes. If both nometasync and nosync are set, the nosync flag takes
precedence.
* {{F:writemap}}: Use a writable memory map instead of just read-only. This
speeds up write operations but makes the database vulnerable to corruption in
case any bugs in slapd cause stray writes into the mmap region.
* {{F:mapasync}}: When using a writable memory map and performing flushes on
each commit, use an asynchronous flush instead of a synchronous flush (the
default). This option has no effect if writemap has not been set. It also has
no effect if nosync is set.
* {{F:nordahead}}: Turn off file readahead. Usually the OS performs readahead
on every read request. This usually boosts read performance but can be
harmful to random access read performance if the system's memory is full and
the DB is larger than RAM. This option is not implemented on Windows.
H4: olcDbIndex: {<attrlist> | default} [pres,eq,approx,sub,none]
This directive specifies the indices to maintain for the given
attribute. If only an {{EX:<attrlist>}} is given, the default
indices are maintained. The index keywords correspond to the
common types of matches that may be used in an LDAP search filter.
\Example:
> olcDbIndex: default pres,eq
> olcDbIndex: uid
> olcDbIndex: cn,sn pres,eq,sub
> olcDbIndex: objectClass eq
The first line sets the default set of indices to maintain to
present and equality. The second line causes the default (pres,eq)
set of indices to be maintained for the {{EX:uid}} attribute type.
The third line causes present, equality, and substring indices to
be maintained for {{EX:cn}} and {{EX:sn}} attribute types. The
fourth line causes an equality index for the {{EX:objectClass}}
attribute type.
There is no index keyword for inequality matches. Generally these
matches do not use an index. However, some attributes do support
indexing for inequality matches, based on the equality index.
A substring index can be more explicitly specified as {{EX:subinitial}},
{{EX:subany}}, or {{EX:subfinal}}, corresponding to the three
possible components
of a substring match filter. A subinitial index only indexes
substrings that appear at the beginning of an attribute value.
A subfinal index only indexes substrings that appear at the end
of an attribute value, while subany indexes substrings that occur
anywhere in a value.
Note that by default, setting an index for an attribute also
affects every subtype of that attribute. E.g., setting an equality
index on the {{EX:name}} attribute causes {{EX:cn}}, {{EX:sn}}, and every other
attribute that inherits from {{EX:name}} to be indexed.
By default, no indices are maintained. It is generally advised
that minimally an equality index upon objectClass be maintained.
> olcDbIndex: objectClass eq
Additional indices should be configured corresponding to the
most common searches that are used on the database.
Presence indexing should not be configured for an attribute
unless the attribute occurs very rarely in the database, and
presence searches on the attribute occur very frequently during
normal use of the directory. Most applications don't use presence
searches, so usually presence indexing is not very useful.
If this setting is changed while slapd is running, an internal task
will be run to generate the changed index data. All server operations
can continue as normal while the indexer does its work. If slapd is
stopped before the index task completes, indexing will have to be
manually completed using the slapindex tool.
H4: olcDbMaxEntrySize: <bytes>
Specify the maximum size of an entry in bytes. Attempts to store
an entry larger than this size will be rejected with the error
LDAP_ADMINLIMIT_EXCEEDED. The default is 0, which is unlimited.
H4: olcDbMaxReaders: <integer>
This directive specifies the maximum number of threads that may have
concurrent read access to the database. Tools such as slapcat count as a
single thread, in addition to threads in any active slapd processes. The
default is 126.
H4: olcDbMaxSize: <bytes>
This directive specifies the maximum size of the database in bytes. A memory
map of this size is allocated at startup time and the database will not be
allowed to grow beyond this size. The default is 10485760 bytes (10MB). This
setting may be changed upward if the configured limit needs to be increased.
Note: It is important to set this to as large a value as possible, (relative
to anticipated growth of the actual data over time) since growing the size
later may not be practical when the system is under heavy load.
H4: olcDbMode: { <octal> | <symbolic> }
This directive specifies the file protection mode that newly
created database index files should have. This can be in the form
{{EX:0600}} or {{EX:-rw-------}}
\Default:
> olcDbMode: 0600
H4: olcDbMultival: { <attrlist> | default } <integer> hi,<integer> lo
Specify the number of values for which a multivalued attribute is
stored in a separate table. Normally entries are stored as a single
blob inside the database. When an entry gets very large or contains
attributes with a very large number of values, modifications on that
entry may get very slow. Splitting the large attributes out to a separate
table can improve the performance of modification operations.
The threshold is specified as a pair of integers. If the number of
values exceeds the hi threshold the values will be split out. If
a modification deletes enough values to bring an attribute below
the lo threshold the values will be removed from the separate
table and merged back into the main entry blob.
The threshold can be set for a specific list of attributes, or
the default can be configured for all other attributes.
The default value for both hi and lo thresholds is UINT_MAX, which keeps
all attributes in the main blob.
In addition to increasing write performance of operations the use of
multival can also decrease fragmentation of the primary {{TERM:MDB}} database.
H4: olcDbRtxnsize: <entries>
This directive specifies the maximum number of entries to process in a single
read transaction when executing a large search. Long-lived read transactions
prevent old database pages from being reused in write transactions, and so
can cause significant growth of the database file when there is heavy write
traffic. This setting causes the read transaction in large searches to be
released and reacquired after the given number of entries has been read, to
give writers the opportunity to reclaim old database pages. The default is
10000.
H4: olcDbSearchStack: <integer>
Specify the depth of the stack used for search filter evaluation.
Search filters are evaluated on a stack to accommodate nested {{EX:AND}} /
{{EX:OR}} clauses. An individual stack is allocated for each server thread.
The depth of the stack determines how complex a filter can be evaluated
without requiring any additional memory allocation. Filters that are
nested deeper than the search stack depth will cause a separate stack to
be allocated for that particular search operation. These separate allocations
can have a major negative impact on server performance, but specifying
too much stack will also consume a great deal of memory. Each search
uses 512K bytes per level on a 32-bit machine, or 1024K bytes per level
on a 64-bit machine. The default stack depth is 16, thus 8MB or 16MB
per thread is used on 32 and 64 bit machines, respectively. Also the
512KB size of a single stack slot is set by a compile-time constant which
may be changed if needed; the code must be recompiled for the change
to take effect.
\Default:
> olcDbSearchStack: 16
H4: olcDbNosync: { TRUE | FALSE }
This directive causes on-disk database contents to not be immediately
synchronized with in memory changes upon change. Setting this option
to {{EX:TRUE}} may improve performance at the expense of data integrity.
H4: Sample Entry
>dn: olcDatabase=mdb,cn=config
>objectClass: olcDatabaseConfig
>objectClass: olcMdbConfig
>olcDatabase: mdb
>olcSuffix: dc=example,dc=com
>olcDbDirectory: /usr/local/var/openldap-data
>olcDbIndex: objectClass eq
H2: Configuration Example
The following is an example configuration, interspersed
with explanatory text. It defines two databases to handle
different parts of the {{TERM:X.500}} tree; both are {{TERM:MDB}}
database instances. The line numbers shown are provided for
reference only and are not included in the actual file. First, the
global configuration section:
E: 1. # example config file - global configuration entry
E: 2. dn: cn=config
E: 3. objectClass: olcGlobal
E: 4. cn: config
E: 5. olcReferral: ldap://root.openldap.org
E: 6.
Line 1 is a comment. Lines 2-4 identify this as the global
configuration entry.
The {{EX:olcReferral:}} directive on line 5
means that queries not local to one of the databases defined
below will be referred to the LDAP server running on the
standard port (389) at the host {{EX:root.openldap.org}}.
Line 6 is a blank line, indicating the end of this entry.
E: 7. # internal schema
E: 8. dn: cn=schema,cn=config
E: 9. objectClass: olcSchemaConfig
E: 10. cn: schema
E: 11.
Line 7 is a comment. Lines 8-10 identify this as the root of
the schema subtree. The actual schema definitions in this entry
are hardcoded into slapd so no additional attributes are specified here.
Line 11 is a blank line, indicating the end of this entry.
E: 12. # include the core schema
E: 13. include: file:///usr/local/etc/openldap/schema/core.ldif
E: 14.
Line 12 is a comment. Line 13 is an LDIF include directive which
accesses the {{core}} schema definitions in LDIF format. Line 14
is a blank line.
Next comes the database definitions. The first database is the
special {{EX:frontend}} database whose settings are applied globally
to all the other databases.
E: 15. # global database parameters
E: 16. dn: olcDatabase=frontend,cn=config
E: 17. objectClass: olcDatabaseConfig
E: 18. olcDatabase: frontend
E: 19. olcAccess: to * by * read
E: 20.
Line 15 is a comment. Lines 16-18 identify this entry as the global
database entry. Line 19 is a global access control. It applies to all
entries (after any applicable database-specific access controls).
Line 20 is a blank line.
The next entry defines the config backend.
E: 21. # set a rootpw for the config database so we can bind.
E: 22. # deny access to everyone else.
E: 23. dn: olcDatabase=config,cn=config
E: 24. objectClass: olcDatabaseConfig
E: 25. olcDatabase: config
E: 26. olcRootPW: {SSHA}XKYnrjvGT3wZFQrDD5040US592LxsdLy
E: 27. olcAccess: to * by * none
E: 28.
Lines 21-22 are comments. Lines 23-25 identify this entry as the config
database entry. Line 26 defines the {{super-user}} password for this
database. (The DN defaults to {{"cn=config"}}.) Line 27 denies all access
to this database, so only the super-user will be able to access it. (This
is already the default access on the config database. It is just listed
here for illustration, and to reiterate that unless a means to authenticate
as the super-user is explicitly configured, the config database will be
inaccessible.)
Line 28 is a blank line.
The next entry defines an MDB backend that will handle queries for things
in the "dc=example,dc=com" portion of the tree. Indices are to be maintained
for several attributes, and the {{EX:userPassword}} attribute is to be
protected from unauthorized access.
E: 29. # MDB definition for example.com
E: 30. dn: olcDatabase=mdb,cn=config
E: 31. objectClass: olcDatabaseConfig
E: 32. objectClass: olcMdbConfig
E: 33. olcDatabase: mdb
E: 34. olcSuffix: dc=example,dc=com
E: 35. olcDbDirectory: /usr/local/var/openldap-data
E: 36. olcRootDN: cn=Manager,dc=example,dc=com
E: 37. olcRootPW: secret
E: 38. olcDbIndex: uid pres,eq
E: 39. olcDbIndex: cn,sn pres,eq,approx,sub
E: 40. olcDbIndex: objectClass eq
E: 41. olcAccess: to attrs=userPassword
E: 42. by self write
E: 43. by anonymous auth
E: 44. by dn.base="cn=Admin,dc=example,dc=com" write
E: 45. by * none
E: 46. olcAccess: to *
E: 47. by self write
E: 48. by dn.base="cn=Admin,dc=example,dc=com" write
E: 49. by * read
E: 50.
Line 29 is a comment. Lines 30-33 identify this entry as a MDB database
configuration entry. Line 34 specifies the DN suffix
for queries to pass to this database. Line 35 specifies the directory
in which the database files will live.
Lines 36 and 37 identify the database {{super-user}} entry and associated
password. This entry is not subject to access control or size or
time limit restrictions.
Lines 38 through 40 indicate the indices to maintain for various
attributes.
Lines 41 through 49 specify access control for entries in this
database. For all applicable entries, the {{EX:userPassword}} attribute is writable
by the entry itself and by the "admin" entry. It may be used for
authentication/authorization purposes, but is otherwise not readable.
All other attributes are writable by the entry and the "admin"
entry, but may be read by all users (authenticated or not).
Line 50 is a blank line, indicating the end of this entry.
The next entry defines another
MDB database. This one handles queries involving the
{{EX:dc=example,dc=net}} subtree but is managed by the same entity
as the first database. Note that without line 60, the read access
would be allowed due to the global access rule at line 19.
E: 51. # MDB definition for example.net
E: 52. dn: olcDatabase=mdb,cn=config
E: 53. objectClass: olcDatabaseConfig
E: 54. objectClass: olcMdbConfig
E: 55. olcDatabase: mdb
E: 56. olcSuffix: dc=example,dc=net
E: 57. olcDbDirectory: /usr/local/var/openldap-data-net
E: 58. olcRootDN: cn=Manager,dc=example,dc=com
E: 59. olcDbIndex: objectClass eq
E: 60. olcAccess: to * by users read
H2: Converting old style {{slapd.conf}}(5) file to {{cn=config}} format
Before converting to the {{cn=config}} format you should make sure that the
config backend is properly configured in your existing config file. While
the config backend is always present inside slapd, by default it is only
accessible by its rootDN, and there are no default credentials assigned
so unless you explicitly configure a means to authenticate to it, it will be
unusable.
If you do not already have a {{EX:database config}} section, add something
like this to the end of {{EX:slapd.conf}}
> database config
> rootpw VerySecret
Note: Since the config backend can be used to load arbitrary code into the
slapd process, it is extremely important to carefully guard whatever
credentials are used to access it. Since simple passwords are vulnerable to
password guessing attacks, it is usually better to omit the rootpw and only
use SASL authentication for the config rootDN.
An existing {{slapd.conf}}(5) file can be converted to the new format using
{{slaptest}}(8) or any of the slap tools:
> slaptest -f /usr/local/etc/openldap/slapd.conf -F /usr/local/etc/openldap/slapd.d
Test that you can access entries under {{EX:cn=config}} using the
default {{rootdn}} and the {{rootpw}} configured above:
> ldapsearch -x -D cn=config -w VerySecret -b cn=config
You can then discard the old {{slapd.conf}}(5) file. Make sure to launch
{{slapd}}(8) with the {{-F}} option to specify the configuration directory
if you are not using the default directory path.
Note: When converting from the slapd.conf format to slapd.d format, any
included files will also be integrated into the resulting configuration
database.
H2: Recovering from a broken configuration
If the server using {{cn=config}} does not start, either because the
configuration does not represent the current version or because it has been
corrupted, these actions are available, in the order of decreasing preference.
Make sure you have made a backup of the "broken" version before you attempt any
of these:
H3: Generate an ldif version of the configuration database and reload from that
Most of the time, the configuration can be parsed and a text version generated
with {{slapcat}}(8):
> slapcat -F /usr/local/etc/openldap/slapd.d -n0 -l extracted_config.ldif
After you have backed up and removed the old configuration database contents,
this output ldif can be hand-edited to adjust or remove the offending entries
and imported again:
> slapadd -F /usr/local/etc/openldap/slapd.d -l updated_config.ldif
> slaptest -F /usr/local/etc/openldap/slapd.d
H3: Modify config in-place
If the configuration can be parsed and you know exactly what you need to do,
you can use {{slapmodify}}(8) to effect the required changes directly:
> slapmodify -F /usr/local/etc/openldap/slapd.d
> dn: ..., cn=config
> changetype: ...
> ...
H3: Recover with plain back-ldif
If the configuration contains items that {{slapd}}(8) cannot process as a
{{cn=config}} database at all, the last resort is to disable schema checking
and operate on it as a regular back-ldif database. This might cease to work
with future versions of OpenLDAP without notice, attempt this only when all of
the above fail.
First, create a directory to serve as the hosting DB and create the structure:
> mkdir ./recovery ./recovery/cn=recovery
> cp /usr/local/etc/openldap/slapd.d/cn=config.ldif ./recovery/cn=recovery
> cp -r /usr/local/etc/openldap/slapd.d/cn=config ./recovery/cn=recovery
Or, if you have already backed up your old configuration, you can symlink it
into place:
> mkdir ./recovery
> ln -s /usr/local/etc/openldap/slapd.d ./recovery/cn=recovery
Next, create a trivial {{slapd.conf}}(5) to access the new database:
> database ldif
> suffix cn=recovery
> directory ./recovery/
Note the change of suffix, {{EX:cn=config}} is hardcoded to correspond to an
active config database, so we have to home it one level deeper - at
{{EX:cn=config,cn=recovery}}.
Now you can use {{slapmodify}}(8) to modify the database, it is most likely you
will need to run with schema checking disabled:
> slapmodify -f ./recovery.conf -s
You can test the validity of your config with {{slaptest}}(8):
> slaptest -F ./recovery/cn=recovery
And generate a full ldif with {{slapcat}}(8):
> slapcat -F ./recovery/cn=recovery -n0