Preliminary slapd.d info, very incomplete

[openldap] / doc / guide / admin / slapdconf2.sdf

# $OpenLDAP$
# Copyright 2005, 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. Unlike previous
OpenLDAP releases, the slapd runtime configuration in 2.3 is
fully LDAP-enabled and can be managed using the standard LDAP
operations with data in LDIF. The LDAP configuration engine
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. The old style {{slapd.conf}}(5) file is still
supported, but must be converted to the new {{slapd.d}}(5) format
to allow runtime changes to be saved. While the old style
configuration uses a single file, normally installed as
{{F:/usr/local/etc/openldap/slapd.conf}}, the new style
uses a slapd backend database to store the configuration. The
the configuration database normally resides in the
{{F:/usr/local/etc/openldap/slapd.d}} directory.

An alternate configuration directory (or file) can be specified via a
command-line option to {{slapd}}(8) or {{slurpd}}(8). This chapter
describes the general format of the configuration system , followed by a
detailed description of commonly used config directives.


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.gif"; 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.d}} 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:
* Include files
.. Usually these are just pathnames left over from a converted
{{EX:slapd.conf}} file.
.. Otherwise use of Include files is deprecated.
* 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 white space, it is considered a
continuation of the previous line (even if the previous line is a
comment). 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={X}<typeA>,cn=config
>       objectClass: olcBackendConfig
>       olcBackend: {X}<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.

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 {{EX:"like this"}}. If
an argument contains a double quote or a backslash character `{{EX:\}}',
the character should be preceded by a backslash character `{{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.d}}(5) manual page.  This section
separates the configuration 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.

Most of the attributes and objectClasses used in the slapd
configuration have a prefix of {{EX:"olc"}} (OpenLDAP Configuration)
in their names.



H3: 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 {{EX:<>}}.


H4: 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 {{SECT:Access Control}} section of this chapter for a
summary of basic usage.

!if 0
More details discussion of this directive can be found in the
{{SECT:Advanced Access Control}} chapter.
!endif

Note: If no {{EX:access}} directives are specified, the default
access control policy, {{EX:access to * by * read}}, allows all
both authenticated and anonymous users read access.


H4: attributetype <{{REF:RFC2252}} 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: 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.


H4: 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.

H4: 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 {{EX:--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 {{EX:-?}}
or consult the table below. The possible values for <integer> are:

!block table; colaligns="RL"; align=Center; \
        title="Table 5.1: Debugging Levels"
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
!endblock

\Example:

E: loglevel -1

This will cause lots and lots of debugging information to be
logged.

\Default:

E: loglevel 256


H4: objectclass <{{REF:RFC2252}} 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: 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.


H4: sizelimit <integer>

This directive specifies the maximum number of entries to return
from a search operation.

\Default:

>       sizelimit 500


H4: 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


H3: 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.

H4: backend <type>

This directive marks the beginning of a backend declaration.
{{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
bdb     Berkeley DB transactional backend
dnssrv  DNS SRV backend
ldap    Lightweight Directory Access Protocol (Proxy) backend
ldbm    Lightweight DBM backend
meta    Meta Directory backend
monitor Monitor backend
passwd  Provides read-only access to {{passwd}}(5)
perl    Perl Programmable backend
shell   Shell (extern program) backend
sql     SQL Programmable backend
!endblock

\Example:

>       backend bdb

This marks the beginning of a new {{TERM:BDB}} backend
definition.


H3: 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.

H4: database <type>

This directive marks the beginning of a database instance
declaration.
{{EX:<type>}} should be one of the
supported backend types listed in Table 5.2.

\Example:

>       database bdb

This marks the beginning of a new {{TERM:BDB}} database instance
declaration.


H4: 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

H4: replica

>       replica uri=ldap[s]://<hostname>[:<port>] | host=<hostname>[:<port>]
>               [bindmethod={simple|kerberos|sasl}]
>               ["binddn=<DN>"]
>               [saslmech=<mech>]
>               [authcid=<identity>]
>               [authzid=<identity>]
>               [credentials=<password>]
>               [srvtab=<filename>]

This directive specifies a replication site for this database. The
{{EX:uri=}} parameter specifies a scheme, 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 or 636) is used.

{{EX:host}} is deprecated in favor of the {{EX:uri}} parameter.

{{EX:uri}} allows the replica LDAP server to be specified as an LDAP 
URI such as {{EX:ldap://slave.example.com:389}} or
{{EX:ldaps://slave.example.com:636}}.

The {{EX: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.  It must also match the {{EX:updatedn}}
directive in the slave slapd's config file.  Generally, this DN
{{should not}} be the same as the {{EX:rootdn}} of the master
database.  Since DNs are likely to contain embedded spaces, the
entire {{EX:"binddn=<DN>"}} string should be enclosed in double
quotes.

The {{EX:bindmethod}} is {{EX:simple}} or {{EX:kerberos}} or {{EX:sasl}},
depending on whether simple password-based authentication or Kerberos
authentication or {{TERM:SASL}} authentication is to be used when connecting
to the slave slapd.

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.

Kerberos authentication is deprecated in favor of SASL authentication
mechanisms, in particular the {{EX:KERBEROS_V4}} and {{EX:GSSAPI}}
mechanisms.  Kerberos authentication requires {{EX:binddn}} and
{{EX:srvtab}} 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.

See the chapter entitled {{SECT:Replication with slurpd}} for more
information on how to use this directive.


H4: 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 {{SECT:Replication with slurpd}} for more
information on how to use this directive.


H4: 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 this database or even 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,cn=example.com,cn=digest-md5,cn=auth"

See the {{SECT:SASL Authentication}} section for information on
SASL authentication identities.


H4: rootpw <password>

This directive can be used to specifies a password for the DN for
the rootdn (when the rootdn is set to a DN within the database).

\Example:

>       rootpw secret

It is also permissible to provide hash of the password in RFC 2307
form.  {{slappasswd}}(8) may be used to generate the password hash.

\Example:

>       rootpw {SSHA}ZKKuqbEKJfKSXhUbHG3fG8MDn9j1v4QN

The hash was generated using the command {{EX:slappasswd -s secret}}.


H4: 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.


H4: syncrepl

>       syncrepl 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>]


This directive specifies the current database as a replica of the
master content by establishing the current {{slapd}}(8) as a
replication consumer site running a syncrepl replication engine.
The master database is located at the replication provider site
specified by the {{EX:provider}} parameter. The replica database is
kept up-to-date with the master content using the LDAP Content
Synchronization protocol. See {{EX:draft-zeilenga-ldup-sync-xx.txt}}
({{a work in progress}}) 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 master 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 at the consumer site, whereas the {{EX:replica}}
specification is located at the provider site. {{EX:syncrepl}} and
{{EX:replica}} directives define two independent replication
mechanisms. They do not represent the replication peers of each other.

The content of the syncrepl replica 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 syncrepl search specification has
the same value syntax and the same default values as in the
{{ldapsearch}}(1) client search tool.

The LDAP Content Synchronization 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. Further updates to the
master replica 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 5 300 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 into the replica content.
Every entry in the replica 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
master 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.

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 syncrepl replication mechanism is supported by the
three native backends: back-bdb, back-hdb, and back-ldbm.

See the {{SECT:LDAP Sync Replication}} chapter of the admin guide
for more information on how to use this directive.


H4: 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,cn=example.com,cn=digest-md5,cn=auth"

See the {{SECT:Replication with slurpd}} chapter for more information
on how to use this directive.

H4: 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 {{TERM:URL}} is provided.

\Example:

>       updateref       ldap://master.example.net


H3: BDB Database Directives

Directives in this category only apply to a {{TERM:BDB}} database.
That is, they must follow a "database bdb" line and come before any
subsequent "backend" or "database" line.  For a complete reference
of BDB configuration directives, see {{slapd-bdb}}(5).


H4: directory <directory>

This directive specifies the directory where the BDB files
containing the database and associated indices live.

\Default:

>       directory /usr/local/var/openldap-data


H3: LDBM Database Directives

Directives in this category only apply to a {{TERM:LDBM}} database.
That is, they must follow a "database ldbm" line and come before
any subsequent "backend" or "database" line.  For a complete reference
of LDBM configuration directives, see {{slapd-ldbm}}(5).

H4: cachesize <integer>

This directive specifies the size in entries of the in-memory
cache maintained by the LDBM backend database instance.

\Default:

>       cachesize 1000


H4: 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 indices.

\Default:

>       dbcachesize 100000


H4: dbnolocking

This option, if present, disables database locking.
Enabling this option may improve performance at the expense
of data security.


H4: dbnosync

This option causes on-disk database contents to not be immediately
synchronized with in memory changes upon change.  Enabling this option
may improve performance at the expense of data integrity.


H4: directory <directory>

This directive specifies the directory where the LDBM files
containing the database and associated indices live.

\Default:

>       directory /usr/local/var/openldap-data


H4: index {<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.

\Example:

>       index default pres,eq
>       index uid
>       index cn,sn pres,eq,sub
>       index 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.

By default, no indices are maintained.  It is generally advised
that minimally an equality index upon objectClass be maintained.

>       index objectClass eq



H4: mode <integer>

This directive specifies the file protection mode that newly
created database index files should have.

\Default:

>       mode 0600


H2: 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[.<basic-style>]=<regex> | dn.<scope-style>=<DN>]
>               [filter=<ldapfilter>] [attrs=<attrlist>]
>       <basic-style> ::= regex | exact
>       <scope-style> ::= base | one | subtree | children
>       <attrlist> ::= <attr> [val[.<basic-style>]=<regex>] | <attr> , <attrlist>
>       <attr> ::= <attrname> | entry | children
>       <who> ::= * | [anonymous | users | self
>                       | dn[.<basic-style>]=<regex> | dn.<scope-style>=<DN>] 
>               [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>]
>       <access> ::= [self]{<level>|<priv>}
>       <level> ::= none | auth | compare | search | read | write
>       <priv> ::= {=|+|-}{w|r|s|c|x|0}+
>       <control> ::= [stop | continue | break]

where the <what> part selects the entries and/or attributes to which
the access applies, the {{EX:<who>}} part specifies which entities
are granted access, and the {{EX:<access>}} part specifies the
access granted. Multiple {{EX:<who> <access> <control>}} triplets
are supported, allowing many entities to be granted different access
to the same set of entries and attributes. Not all of these access
control options are described here; for more details see the
{{slapd.access}}(5) man page.


H3: What to control access to

The <what> part of an access specification determines the entries
and attributes to which the access control applies.  Entries are
commonly selected in two ways: by DN and by filter.  The following
qualifiers select entries by DN:

>       to *
>       to dn[.<basic-style>]=<regex>
>       to dn.<scope-style>=<DN>

The first form is used to select all entries.  The second form may
be used to select entries by matching a regular expression against
the target entry's {{normalized DN}}.   (The second form is not
discussed further in this document.)  The third form is used to
select entries which are within the requested scope of DN.  The
<DN> is a string representation of the Distinguished Name, as
described in {{REF:RFC2253}}.

The scope can be either {{EX:base}}, {{EX:one}}, {{EX:subtree}},
or {{EX:children}}.  Where {{EX:base}} matches only the entry with
provided DN, {{EX:one}} matches the entries whose parent is the
provided DN, {{EX:subtree}} matches all entries in the subtree whose
root is the provided DN, and {{EX:children}} matches all entries
under the DN (but not the entry named by the DN).

For example, if the directory contained entries named:

>       0: o=suffix
>       1: cn=Manager,o=suffix
>       2: ou=people,o=suffix
>       3: uid=kdz,ou=people,o=suffix
>       4: cn=addresses,uid=kdz,ou=people,o=suffix
>       5: uid=hyc,ou=people,o=suffix

\Then:
. {{EX:dn.base="ou=people,o=suffix"}} match 2;
. {{EX:dn.one="ou=people,o=suffix"}} match 3, and 5;
. {{EX:dn.subtree="ou=people,o=suffix"}} match 2, 3, 4, and 5; and
. {{EX:dn.children="ou=people,o=suffix"}} match 3, 4, and 5.


Entries may also be selected using a filter:

>       to filter=<ldap filter>

where <ldap filter> is a string representation of an LDAP
search filter, as described in {{REF:RFC2254}}.  For example:

>       to filter=(objectClass=person)

Note that entries may be selected by both DN and filter by
including both qualifiers in the <what> clause.

>       to dn.one="ou=people,o=suffix" filter=(objectClass=person)

Attributes within an entry are selected by including a comma-separated
list of attribute names in the <what> selector:

>       attrs=<attribute list>

A specific value of an attribute is selected by using a single
attribute name and also using a value selector:

>       attrs=<attribute> val[.<style>]=<regex>

There are two special {{pseudo}} attributes {{EX:entry}} and
{{EX:children}}.  To read (and hence return) a target entry, the
subject must have {{EX:read}} access to the target's {{entry}}
attribute.  To add or delete an entry, the subject must have
{{EX:write}} access to the entry's {{EX:entry}} attribute AND must
have {{EX:write}} access to the entry's parent's {{EX:children}}
attribute.  To rename an entry, the subject must have {{EX:write}}
access to entry's {{EX:entry}} attribute AND have {{EX:write}}
access to both the old parent's and new parent's {{EX:children}}
attributes.  The complete examples at the end of this section should
help clear things up.

Lastly, there is a special entry selector {{EX:"*"}} that is used to
select any entry.  It is used when no other {{EX:<what>}}
selector has been provided.  It's equivalent to "{{EX:dn=.*}}"


H3: 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:

!block table; align=Center; coltags="EX,N"; \
        title="Table 5.3: Access 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[.<basic-style>]=<regex>|Users matching a regular expression
dn.<scope-style>=<DN>|Users within scope of a DN
!endblock

The DN specifier behaves much like <what> clause DN specifiers.

Other control factors are also supported.  For example, a {{EX:<who>}}
can be restricted 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).

Some factors may not be appropriate in all environments (or any).
For example, the domain factor relies on IP to domain name lookups.
As these can easily spoofed, the domain factor should not be avoided.


H3: The access to grant


The kind of <access> granted can be one of the following:


!block table; colaligns="LRL"; coltags="EX,EX,N"; align=Center; \
        title="Table 5.4: Access Levels"
Level   Privileges      Description
none    =0              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
!endblock

Each level implies all lower levels of access. So, for
example, granting someone {{EX:write}} access to an entry also
grants them {{EX:read}}, {{EX:search}}, {{EX:compare}}, and 
{{EX:auth}} access.  However, one may use the privileges specifier
to grant specific permissions.


H3: 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 {{EX:<what>}} selectors given in the configuration file.
For each entry, access controls provided in the database which holds
the entry (or the first database if not held in any database) apply
first, followed by the 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 {{EX:<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 {{EX:<who>}}
selectors within the access directive selected above in the order
in which they appear. It stops with the first {{EX:<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
{{EX:<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 {{EX:<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.



H3: Access Control Examples

The access control facility described above is quite powerful.  This
section shows some examples of its use for descriptive purposes.

A simple example:

>       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 the user to modify their entry, allows anonymous
to authentication against these entries, and allows all others to
read these entries.  Note that only the first {{EX:by <who>}} clause
which matches applies.  Hence, the anonymous users are granted
{{EX:auth}}, not {{EX:read}}.  The last clause could just as well
have been "{{EX:by users read}}".

It is often desirable to restrict operations based upon the level
of protection in place.  The following shows how security strength
factors (SSF) can be used.

>       access to *
>               by ssf=128 self write
>               by ssf=64 anonymous auth
>               by ssf=64 users read

This directive allows users to modify their own entries if security
protections have of strength 128 or better have been established,
allows authentication access to anonymous users, and read access
when 64 or better security protections have been established.  If
client has not establish sufficient security protections, the
implicit {{EX:by * none}} clause would be applied.

The following example shows the use of a style specifiers to select
the entries by DN in two access directives where ordering is
significant.

>       access to dn.children="dc=example,dc=com"
>               by * search
>       access to dn.children="dc=com"
>               by * read

Read access is granted to entries under the {{EX:dc=com}} subtree,
except for those entries under the {{EX:dc=example,dc=com}} subtree,
to which search access is granted.  No access is granted to
{{EX: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 entries under {{EX:dc=example,dc=com}}
are also under {{EX:dc=com}} entries.

Also note that if no {{EX:access to}} directive matches or no {{EX:by
<who>}} clause, {{B:access is denied}}.  That is, every {{EX:access
to}} directive ends with an implicit {{EX:by * none}} clause and
every access list ends with an implicit {{EX:access to * by * none}}
directive.

The next example again shows the importance of ordering, both of
the access directives and the {{EX:by <who>}} clauses.  It also
shows the use of an attribute selector to grant access to a specific
attribute and various {{EX:<who>}} selectors.

>       access to dn.subtree="dc=example,dc=com" attr=homePhone
>               by self write
>               by dn.children=dc=example,dc=com" search
>               by peername.regex=IP:10\..+ read
>       access to dn.subtree="dc=example,dc=com"
>               by self write
>               by dn.children="dc=example,dc=com" search
>               by anonymous auth

This example applies to entries in the "{{EX:dc=example,dc=com}}"
subtree. To all attributes except {{EX:homePhone}}, an entry can
write to itself, entries under {{EX:example.com}} entries can search
by them, anybody else has no access (implicit {{EX:by * none}})
excepting for authentication/authorization (which is always done
anonymously).  The {{EX:homePhone}} attribute is writable by the
entry, searchable by entries under {{EX:example.com}}, readable by
clients connecting from network 10, and otherwise not readable
(implicit {{EX:by * none}}).  All other access is denied by the
implicit {{EX: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 {{EX:<who>}} selector says that the access applies to
entries listed in the {{EX:member}} attribute. The {{EX: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.

!if 0
For more details on how to use the {{EX:access}} directive,
consult the {{Advanced Access Control}} chapter.
!endif


H2: Configuration File Example

The following is an example configuration file, interspersed
with explanatory text. It defines two databases to handle
different parts of the {{TERM:X.500}} tree; both are {{TERM:BDB}}
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 section
E:  2.  include /usr/local/etc/schema/core.schema
E:  3.  referral ldap://root.openldap.org
E:  4.  access to * by * read
 
Line 1 is a comment. Line 2 includes another config file
which contains {{core}} schema definitions.
The {{EX: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 {{EX:root.openldap.org}}.

Line 4 is a global access control.  It applies to all
entries (after any applicable database-specific access
controls).

The next section of the configuration file defines a BDB
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. Indices are to be
maintained for several attributes, and the {{EX:userPassword}}
attribute is to be protected from unauthorized access.

E:  5.  # BDB definition for the example.com
E:  6.  database bdb
E:  7.  suffix "dc=example,dc=com"
E:  8.  directory /usr/local/var/openldap-data
E:  9.  rootdn "cn=Manager,dc=example,dc=com"
E: 10.  rootpw secret
E: 11.  # replication directives
E: 12.  replogfile /usr/local/var/openldap/slapd.replog
E: 13.  replica uri=ldap://slave1.example.com:389
E: 14.          binddn="cn=Replicator,dc=example,dc=com"
E: 15.          bindmethod=simple credentials=secret
E: 16.  replica uri=ldaps://slave2.example.com:636
E: 17.          binddn="cn=Replicator,dc=example,dc=com"
E: 18.          bindmethod=simple credentials=secret
E: 19.  # indexed attribute definitions
E: 20.  index uid pres,eq
E: 21.  index cn,sn,uid pres,eq,approx,sub
E: 22.  index objectClass eq
E: 23.  # database access control definitions
E: 24.  access to attr=userPassword
E: 25.          by self write
E: 26.          by anonymous auth
E: 27.          by dn.base="cn=Admin,dc=example,dc=com" write
E: 28.          by * none
E: 29.  access to *
E: 30.          by self write
E: 31.          by dn.base="cn=Admin,dc=example,dc=com" write
E: 32.          by * 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 12 specifies the
replication log file (where changes to the database are logged -
this file is written by slapd and read by slurpd). Lines 13 through
15 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 16 through 18 specify
a second replication site.  See the {{SECT:Replication with slurpd}}
chapter for more information on these directives.

Lines 20 through 22 indicate the indices to maintain for various
attributes.

Lines 24 through 32 specify access control for entries in this
database.  As this is the first database, the controls also apply
to entries not held in any database (such as the Root DSE).  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).

The next section of the example configuration file defines another
BDB 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 39, the read access
would be allowed due to the global access rule at line 4.

E: 33.  # BDB definition for example.net
E: 34.  database bdb
E: 35.  suffix "dc=example,dc=net"
E: 36.  directory /usr/local/var/openldap-data-net
E: 37.  rootdn "cn=Manager,dc=example,dc=com"
E: 38.  index objectClass eq
E: 39.  access to * by users read