5. The slapd Configuration File
Once the software has been built and installed, you are ready to configure slapd(8) for use at your site. The slapd runtime configuration is primarily accomplished through the slapd.conf(5) file, normally installed in the /usr/local/etc/openldap directory.
An alternate configuration file can be specified via a command-line option to slapd(8) or slurpd(8). This chapter describes the general format of the config file, followed by a detailed description of commonly used config file directives.
5.1. Configuration File Format
The slapd.conf(5) file consists of three types of configuration information: global, backend specific, and database specific. Global information is specified first, followed by information associated with a particular backend type, which is then followed by information associated with a particular database instance. Global directives can be overridden in a backend and/or database directives, backend directives can be overridden by database directives.
Blank lines and comment lines beginning with a '#' character are ignored. If a line begins with white space, it is considered a continuation of the previous line. The general format of slapd.conf is as follows:
# global configuration directives
<global config directives>
# backend definition
backend <typeA>
<backend-specific directives>
# first database definition & config directives
database <typeA>
<database-specific directives>
# second database definition & config directives
database <typeB>
<database-specific directives>
# second database definition & config directives
database <typeA>
<database-specific directives>
# subsequent backend & database definitions & config directives
...
A configuration directive may take arguments. If so, they are separated by white space. If an argument contains white space, the argument should be enclosed in double quotes "like this". If an argument contains a double quote or a backslash character `\', the character should be preceded by a backslash character `\'.
The distribution contains an example configuration file that will be installed in the /usr/local/etc/openldap directory. A number of files containing schema definitions (attribute types and object classes) are also provided in the /usr/local/etc/openldap/schema directory.
5.2. Configuration File Directives
This section details commonly used configuration directives. For a complete list, see slapd.conf(5) manual page. This section separates the configuration file directives into global, backend-specific and data-specific categories, describing each directive and its default value (if any), and giving an example of its use.
5.2.1. Global Directives
Directives described in this section apply to all backends and databases unless specifically overridden in a backend or database definition. Arguments that should be replaced by actual text are shown in brackets <>.
5.2.1.1. access 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 requesters (specified by <who>). See the Access Control section of this chapter for a summary of basic usage.
5.2.1.2. attributetype <RFC2252 Attribute Type Description>
This directive defines an attribute type. Please see the Schema Specification chapter for information regarding how to use this directive.
5.2.1.3. defaultaccess { none | compare | search | read | write }
This directive specifies the default access to grant requesters when no access directives have been specified. Any given access level implies all lesser access levels (e.g., read access implies search and compare but not write).
Note: It is recommend that the access directive be used to specify access control. See the Access Control section of this chapter for information regarding the access directive.
Default:
defaultaccess read
5.2.1.4. idletimeout <integer>
Specify the number of seconds to wait before forcibly closing an idle client connection. An idletimeout of 0, the default, disables this feature.
5.2.1.5. include <filename>
This directive specifies that slapd should read additional configuration information from the given file before continuing with the next line of the current file. The included file should follow the normal slapd config file format. The file is commonly used to include files containing schema specifications.
Note: You should be careful when using this directive - there is no small limit on the number of nested include directives, and no loop detection is done.
5.2.1.6. loglevel <integer>
This directive specifies the level at which debugging statements and operation statistics should be syslogged (currently logged to the syslogd(8) {EX:LOG_LOCAL4}} facility). You must have configured OpenLDAP --enable-debug (the default) for this to work (except for the two statistics levels, which are always enabled). Log levels are additive. To display what numbers correspond to what kind of debugging, invoke slapd with -? or consult the table below. The possible values for <integer> are:
| Level | Description |
| -1 | enable all debugging |
| 0 | no debugging |
| 1 | trace function calls |
| 2 | debug packet handling |
| 4 | heavy trace debugging |
| 8 | connection management |
| 16 | print out packets sent and received |
| 32 | search filter processing |
| 64 | configuration file processing |
| 128 | access control list processing |
| 256 | stats log connections/operations/results |
| 512 | stats log entries sent |
| 1024 | print communication with shell backends |
| 2048 | print entry parsing debugging |
Example:
loglevel -1
This will cause lots and lots of debugging information to be logged.
Default:
loglevel 256
5.2.1.7. objectclass <RFC2252 Object Class Description>
This directive defines an object class. Please see the Schema Specification chapter for information regarding how to use this directive.
5.2.1.8. referral <URI>
This directive specifies the referral to pass back when slapd cannot find a local database to handle a request.
Example:
referral 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.
5.2.1.9. sizelimit <integer>
This directive specifies the maximum number of entries to return from a search operation.
Default:
sizelimit 500
5.2.1.10. timelimit <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:
timelimit 3600
5.2.2. General Backend Directives
Directives in this section apply only to the backend in which they are defined. They are supported by every type of backend. Backend directives apply to all databases instances of the same type and, depending on the directive, may be overridden by database directives.
5.2.2.1. backend <type>
This directive marks the beginning of a backend definition. <type> should be one of ldbm, shell, passwd, or other supported backend type.
5.2.3. General Database Directives
Directives in this section apply only to the database in which they are defined. They are supported by every type of database.
5.2.3.1. database <type>
This directive marks the beginning of a new database instance definition. <type> should be one of ldbm, shell, passwd, or other supported database type.
Example:
database ldbm
This marks the beginning of a new LDBM backend database instance definition.
5.2.3.2. readonly { on | off }
This directive puts the database into "read-only" mode. Any attempts to modify the database will return an "unwilling to perform" error.
Default:
readonly off
5.2.3.3. replica
replica host=<hostname>[:<port>]
[bindmethod={ simple | kerberos | sasl }]
["binddn=<DN>"]
[mech=<mech>]
[authcid=<identity>]
[authzid=<identity>]
[credentials=<password>]
[srvtab=<filename>]
This directive specifies a replication site for this database. The host= parameter specifies a host and optionally a port where the slave slapd instance can be found. Either a domain name or IP address may be used for <hostname>. If <port> is not given, the standard LDAP port number (389) is used.
The binddn= parameter gives the DN to bind as for updates to the slave slapd. It should be a DN which has read/write access to the slave slapd's database, typically given as a rootdn in the slave's config file. It must also match the updatedn directive in the slave slapd's config file. Since DNs are likely to contain embedded spaces, the entire "binddn=<DN>" string should be enclosed in double quotes.
The bindmethod is simple or kerberos or sasl, depending on whether simple password-based authentication or Kerberos authentication or
Simple authentication should not be used unless adequate integrity and privacy protections are in place (e.g. TLS or IPSEC). Simple authentication requires specification of binddn and credentials parameters.
Kerberos authentication is deprecated in favor of SASL authentication mechanisms, in particular the KERBEROS_V4 and GSSAPI mechanisms. Kerberos authentication requires binddn and srvtab parameters.
SASL authentication is generally recommended. SASL authentication requires specification of a mechanism using the mech parameter. Depending on the mechanism, an authentication identity and/or credentials can be specified using authcid and credentials respectively. The authzid parameter may be used to specify an authorization identity.
See the chapter entitled Replication with slurpd for more information on how to use this directive.
5.2.3.4. replogfile <filename>
This directive specifies the name of the replication log file to which slapd will log changes. The replication log is typically written by slapd and read by slurpd. Normally, this directive is only used if slurpd is being used to replicate the database. However, you can also use it to generate a transaction log, if slurpd is not running. In this case, you will need to periodically truncate the file, since it will grow indefinitely otherwise.
See the chapter entitled Replication with slurpd for more information on how to use this directive.
5.2.3.5. rootdn <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 the directory. The DN may refer to a SASL identity.
Entry-based Example:
rootdn "cn=Manager,dc=example,dc=com"
SASL-based Example:
rootdn "uid=root@EXAMPLE.COM"
5.2.3.6. rootpw <password>
This directive specifies a password for the DN given above that will always work, regardless of whether an entry with the given DN exists or has a password. This directive is deprecated in favor of SASL based authentication.
Example:
rootpw secret
5.2.3.7. suffix <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 at least one is required for each database definition.
Example:
suffix "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 line(s) in each database definition in the order they appear in the file. Thus, if one database suffix is a prefix of another, it must appear after it in the config file.
5.2.3.8. updatedn <dn>
This directive is only applicable in a slave slapd. It specifies the DN allowed to make changes to the replica. This may be the DN slurpd(8) binds as when making changes to the replica or the DN associated with a SASL identity.
Entry-based Example:
updatedn "cn=Update Daemon,dc=example,dc=com"
SASL-based Example:
updatedn "uid=slurpd@EXAMPLE.COM"
See the
5.2.3.9. updateref <URL>
This directive is only applicable in a slave slapd. It specifies the URL to return to clients which submit update requests upon the replica. If specified multiple times, each
Example:
updateref ldap://master.example.net
5.2.4. LDBM Backend-Specific Directives
Directives in this category only apply to the LDBM backend database. That is, they must follow a "database ldbm" line and come before any other "database" line.
5.2.4.1. cachesize <integer>
This directive specifies the size in entries of the in-memory cache maintained by the LDBM backend database instance.
Default:
cachesize 1000
5.2.4.2. dbcachesize <integer>
This directive specifies the size in bytes of the in-memory cache associated with each open index file. If not supported by the underlying database method, this directive is ignored without comment. Increasing this number uses more memory but can cause a dramatic performance increase, especially during modifies or when building indexes.
Default:
dbcachesize 100000
5.2.4.3. dbnolocking
This option, if present, disables database locking. Enabling this option may improve performance at the expense of data security.
5.2.4.4. dbnosync
This option causes on-disk database contents not be immediately synchronized with in memory changes upon change. Enabling this option may improve performance at the expense of data security.
5.2.4.5. directory <directory>
This directive specifies the directory where the LDBM files containing the database and associated indexes live.
Default:
directory /usr/local/var/openldap-ldbm
5.2.4.6. index {<attrlist> | default} [pres,eq,approx,sub,none]
This directive specifies the indexes to maintain for the given attribute. If only an <attrlist> is given, the default indexes are maintained.
Example:
index default pres,eq
index objectClass,uid
index cn,sn eq,sub,approx
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 objectClass and uid attribute types. The third line causes equality, substring, and approximate indices to be maintained for cn and sn attribute types.
5.2.4.7. mode <integer>
This directive specifies the file protection mode that newly created database index files should have.
Default:
mode 0600
5.2.5. Other Backend Databases
slapd(8) supports a number of backend database types besides the default LDBM.
| Types | Description |
| ldbm | Berkeley or GNU DBM compatible backend |
| passwd | Provides read-only access to /etc/passwd |
| shell | Shell (extern program) backend |
| sql | SQL Programmable backend |
See slapd.conf(5) for details.
5.3. Access Control
Access to slapd entries and attributes is controlled by the access configuration file directive. The general form of an access line is:
<access directive> ::= access to <what>
[by <who> <access> <control>]+
<what> ::= * | [ dn[.<target style>]=<regex>]
[filter=<ldapfilter>] [attrs=<attrlist>]
<target style> ::= regex | base | one | subtree | children
<attrlist> ::= <attr> | <attr> , <attrlist>
<attr> ::= <attrname> | entry | children
<who> ::= [* | anonymous | users | self |
dn[.<subject style>]=<regex>]
[dnattr=<attrname> ]
[group[/<objectclass>[/<attrname>][.<basic style>]]=<regex> ]
[peername[.<basic style>]=<regex>]
[sockname[.<basic style>]=<regex>]
[domain[.<basic style>]=<regex>]
[sockurl[.<basic style>]=<regex>]
[set=<setspec>]
[aci=<attrname>]
<subject style> ::= regex | exact | base | one | subtree | children
<basic style> ::= regex | exact
<access> ::= [self]{<level>|<priv>}
<level> ::= none | auth | compare | search | read | write
<priv> ::= {=|+|-}{w|r|s|c|x}+
<control> ::= [stop | continue | break]
where the <what> part selects the entries and/or attributes to which the access applies, the <who> part specifies which entities are granted access, and the <access> part specifies the access granted. Multiple <who> <access> <control> triplets are supported, allowing many entities to be granted different access to the same set of entries and attributes.
5.3.1. What to control access to
The <what> part of an access specification determines the entries and attributes to which the access control applies. Entries can be selected in two ways: by a regular expression matching the entry's distinguished name:
dn=<regular expression>
Note: The DN pattern specified should be "normalized" to the RFC2253 restricted DN form. In particular, there should be no extra spaces and commas should be used to separate components. An example normalized DN is "cn=Babs Jensen,dc=example,dc=com". An example of a non-normalized DN is "cn=Babs Jensen; dc=example; dc=com".
Or, entries may be selected by a filter matching some attribute(s) in the entry:
filter=<ldap filter>
where <ldap filter> is a string representation of an LDAP search filter, as described in RFC2254.
Attributes within an entry are selected by including a comma-separated list of attribute names in the <what> selector:
attrs=<attribute list>
Access to the entry itself must be granted or denied using the special attribute name "entry". Note that giving access to an attribute is not enough; access to the entry itself through the entry attribute is also required. The complete examples at the end of this section should help clear things up.
Lastly, there is a special entry selector "*" that is used to select any entry. It is used when no other <what> selector has been provided. It's equivalent to "dn=.*"
5.3.2. Who to grant access to
The <who> part identifies the entity or entities being granted access. Note that access is granted to "entities" not "entries." The following table summarizes entity specifiers:
| Specifier | Entities |
| * | All, including anonymous and authenticated users |
| anonymous | Anonymous (non-authenticated) users |
| users | Authenticated users |
| self | User associated with target entry |
| dn=<regex> | Users matching regular expression |
The DN specifier takes a regular expression which is used to match against the "normalized" DN of the current entity.
dn=<regular expression>
By "normalized", we mean that all extra spaces have been removed from the entity's DN and commas are used to separate RDN components.
Other control factors are also supported. For example, a <what> can be restricted by a regular expression matching the client's domain name:
domain=<regular expression>
or by an entry listed in a DN-valued attribute in the entry to which the access applies:
dnattr=<dn-valued attribute name>
The dnattr specification is used to give access to an entry whose DN is listed in an attribute of the entry (e.g., give access to a group entry to whoever is listed as the owner of the group entry).
5.3.3. The access to grant
The kind of <access> granted can be one of the following:
| Level | Privileges | Description |
| none | no access | |
| auth | =x | needed to bind |
| compare | =cx | needed to compare |
| search | =scx | needed to apply search filters |
| read | =rscx | needed to read search results |
| write | =wrscx | needed to modify/rename |
Each level implies all lower levels of access. So, for example, granting someone write access to an entry also grants them read, search, compare, and auth access. However, one may use the privileges specifier to grant specific permissions.
5.3.4. Access Control Evaluation
When evaluating whether some requester should be given access to an entry and/or attribute, slapd compares the entry and/or attribute to the <what> selectors given in the configuration file. Access directives local to the current database are examined first, followed by global access directives. Within this priority, access directives are examined in the order in which they appear in the config file. Slapd stops with the first <what> selector that matches the entry and/or attribute. The corresponding access directive is the one slapd will use to evaluate access.
Next, slapd compares the entity requesting access to the <who> selectors within the access directive selected above in the order in which they appear. It stops with the first <who> selector that matches the requester. This determines the access the entity requesting access has to the entry and/or attribute.
Finally, slapd compares the access granted in the selected <access> clause to the access requested by the client. If it allows greater or equal access, access is granted. Otherwise, access is denied.
The order of evaluation of access directives makes their placement in the configuration file important. If one access directive is more specific than another in terms of the entries it selects, it should appear first in the config file. Similarly, if one <who> selector is more specific than another it should come first in the access directive. The access control examples given below should help make this clear.
5.3.5. Access Control Examples
The access control facility described above is quite powerful. This section shows some examples of its use. First, some simple examples:
access to * by * read
This access directive grants read access to everyone.
access to *
by self write
by anonymous auth
by * read
This directive allows users to modify their own entries, allows authenticate, and allows authenticated users to read. Note that only the first by <who> clause which matches applies. Hence, the anonymous users are granted auth, not read. The last clause could just as well have been "by users read".
The following example shows the use of a regular expression to select the entries by DN in two access directives where ordering is significant.
access to dn=".*,dc=example,dc=com"
by * search
access to dn=".*,dc=com"
by * read
Read access is granted to entries under the dc=com subtree, except for those entries under the dc=example,dc=com subtree, to which search access is granted. No access is granted to dc=com as neither access directive matches this DN. If the order of these access directives was reversed, the trailing directive would never be reached, since all dc=example,dc=com entries are also dc=com entries.
Also note that if no access to directive matches or no by <who> clause, access is denied. That is, every access to directive ends with an implicit by * none clause and every access list ends with an implicit access to * by * none directive. Only if no access controls are specified is the defaultaccess granted.
The next example again shows the importance of ordering, both of the access directives and the by <who> clauses. It also shows the use of an attribute selector to grant access to a specific attribute and various <who> selectors.
access to dn="(.*,)?dc=example,dc=com" attr=homePhone
by self write
by dn="(.*,)?dc=example,dc=com" search
by domain=.*\.example\.com read
access to dn="(.*,)?dc=example,dc=com"
by self write
by dn=".*,dc=example,dc=com" search
by anonymous auth
This example applies to entries in the "dc=example,dc=com" subtree. To all attributes except homePhone, the entry itself can write them, other example.com entries can search by them, anybody else has no access ((implicit by * none) excepting for authentication/authorization (which is always done anonymously). The homePhone attribute is writable by the entry, searchable by other example.com entries, readable by clients connecting from somewhere in the example.com domain, and otherwise not readable (implicit by * none). All other access is denied by the implicit access to * by * none.
Sometimes it is useful to permit a particular DN to add or remove itself from an attribute. For example, if you would like to create a group and allow people to add and remove only their own DN from the member attribute, you could accomplish it with an access directive like this:
access to attr=member,entry
by dnattr=member selfwrite
The dnattr <who> selector says that the access applies to entries listed in the member attribute. The selfwrite access selector says that such members can only add or delete their own DN from the attribute, not other values. The addition of the entry attribute is required because access to the entry is required to access any of the entry's attributes.
5.4. Configuration File Example
The following is an example configuration file, interspersed with explanatory text. It defines two databases to handle different parts of the
1. # example config file - global configuration section 2. include /usr/local/etc/schema/core.schema 3. referral ldap://root.openldap.org 4. access to * by * read
Line 1 is a comment. Line 2 includes another config file which containing core schema definitions. The referral directive on line 3 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 root.openldap.org.
Line 4 is a global access control. It is used only if no database access controls match or when the target objects are not under the control of any database (such as the Root DSE).
The next section of the configuration file defines an LDBM backend that will handle queries for things in the "dc=example,dc=com" portion of the tree. The database is to be replicated to two slave slapds, one on truelies, the other on judgmentday. Indexes are to be maintained for several attributes, and the userPassword attribute is to be protected from unauthorized access.
5. # ldbm definition for the example.com 6. database ldbm 7. suffix "dc=example,dc=com" 8. directory /usr/local/var/openldap 9. rootdn "cn=Manager,dc=example,dc=com" 10. rootpw secret 11. # replication directives 12. replogfile /usr/local/var/openldap/slapd.replog 13. replica host=slave1.example.com:389 14. binddn="cn=Replicator,dc=example,dc=com" 15. bindmethod=simple credentials=secret 16. replica host=slave2.example.com 17. binddn="cn=Replicator,dc=example,dc=com" 18. bindmethod=simple credentials=secret 19. # indexed attribute definitions 20. index uid pres,eq 21. index cn,sn,uid pres,eq,approx,sub 22. index objectClass eq 23. # ldbm access control definitions 24. access to attr=userPassword 25. by self write 26. by anonymous auth 27. by dn="cn=Admin,dc=example,dc=com" write 28. by * none 29. access to * 30. by self write 31. by dn="cn=Admin,dc=example,dc=com" write 32. by users read
Line 5 is a comment. The start of the database definition is marked by the database keyword on line 6. Line 7 specifies the DN suffix for queries to pass to this database. Line 8 specifies the directory in which the database files will live.
Lines 9 and 10 identify the database "super user" entry and associated password. This entry is not subject to access control or size or time limit restrictions.
Lines 11 through 18 are for replication. Line 11 specifies the replication log file (where changes to the database are logged - this file is written by slapd and read by slurpd). Lines 12 through 14 specify the hostname and port for a replicated host, the DN to bind as when performing updates, the bind method (simple) and the credentials (password) for the binddn. Lines 15 through 18 specify a second replication site. See the Replication with slurpd chapter for more information on these directives.
Lines 20 through 22 indicate the indexes to maintain for various attributes.
Lines 24 through 32 specify access control for entries in the database. For all entries, the 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 authenticated users.
The next section of the example configuration file defines another LDBM database. This one handles queries involving the dc=example,dc=net subtree. Note that without line 38, the read access would be allowed due to the global access rule at line 4.
33. # ldbm definition for example.net 34. database ldbm 35. suffix "dc=example,dc=net" 36. directory /usr/local/var/ldbm-example-net 37. rootdn "cn=Manager,dc=example,dc=com" 38. access to * by users read