slapd.access(5) — Linux manual page


SLAPD.ACCESS(5)              File Formats Manual             SLAPD.ACCESS(5)

NAME         top

       slapd.access  -  access configuration for slapd, the stand-alone LDAP

SYNOPSIS         top


DESCRIPTION         top

       The slapd.conf(5) file contains configuration information for the
       slapd(8) daemon. This configuration file is also used by the SLAPD
       tools slapacl(8), slapadd(8), slapauth(8), slapcat(8), slapdn(8),
       slapindex(8), and slaptest(8).

       The slapd.conf file consists of a series of global configuration
       options that apply to slapd as a whole (including all backends),
       followed by zero or more database backend definitions that contain
       information specific to a backend instance.

       The general format of slapd.conf is as follows:

           # comment - these options apply to every database
           <global configuration options>
           # first database definition & configuration options
           database    <backend 1 type>
           <configuration options specific to backend 1>
           # subsequent database definitions & configuration options

       Both the global configuration and each backend-specific section can
       contain access information.  Backend-specific access control
       directives are used for those entries that belong to the backend,
       according to their naming context.  In case no access control
       directives are defined for a backend or those which are defined are
       not applicable, the directives from the global configuration section
       are then used.

       If no access controls are present, the default policy allows anyone
       and everyone to read anything but restricts updates to rootdn.
       (e.g., "access to * by * read").

       When dealing with an access list, because the global access list is
       effectively appended to each per-database list, if the resulting list
       is non-empty then the access list will end with an implicit access to
       * by * none directive. If there are no access directives applicable
       to a backend, then a default read is used.

       Be warned: the rootdn can always read and write EVERYTHING!

       For entries not held in any backend (such as a root DSE), the global
       directives are used.

       Arguments that should be replaced by actual text are shown in
       brackets <>.


       The structure of the access control directives is

       access to <what> [ by <who> [ <access> ] [ <control> ] ]+
              Grant access (specified by <access>) to a set of entries
              and/or attributes (specified by <what>) by one or more
              requestors (specified by <who>).

       Lists of access directives are evaluated in the order they appear in
       slapd.conf.  When a <what> clause matches the datum whose access is
       being evaluated, its <who> clause list is checked.  When a <who>
       clause matches the accessor's properties, its <access> and <control>
       clauses are evaluated.  Access control checking stops at the first
       match of the <what> and <who> clause, unless otherwise dictated by
       the <control> clause.  Each <who> clause list is implicitly
       terminated by a

            by * none stop

       clause that results in stopping the access control with no access
       privileges granted.  Each <what> clause list is implicitly terminated
       by a

            access to *
                 by * none

       clause that results in granting no access privileges to an otherwise
       unspecified datum.

THE <WHAT> FIELD         top

       The field <what> specifies the entity the access control directive
       applies to.  It can have the forms

            attrs=<attrlist>[ val[/matchingRule][.<attrstyle>]=<attrval>]



       The statement dn=<dnpattern> selects the entries based on their
       naming context.  The <dnpattern> is a string representation of the
       entry's DN.  The wildcard * stands for all the entries, and it is
       implied if no dn form is given.

       The <dnstyle> is optional; however, it is recommended to specify it
       to avoid ambiguities.  Base (synonym of baseObject), the default, or
       exact (an alias of base) indicates the entry whose DN is equal to the
       <dnpattern>; one (synonym of onelevel) indicates all the entries
       immediately below the <dnpattern>, sub (synonym of subtree) indicates
       all entries in the subtree at the <dnpattern>, children indicates all
       the entries below (subordinate to) the <dnpattern>.

       If the <dnstyle> qualifier is regex, then <dnpattern> is a POSIX
       (''extended'') regular expression pattern, as detailed in regex(7)
       and/or re_format(7), matching a normalized string representation of
       the entry's DN.  The regex form of the pattern does not (yet) support

       The statement filter=<ldapfilter> selects the entries based on a
       valid LDAP filter as described in RFC 4515.  A filter of
       (objectClass=*) is implied if no filter form is given.

       The statement attrs=<attrlist> selects the attributes the access
       control rule applies to.  It is a comma-separated list of attribute
       types, plus the special names entry, indicating access to the entry
       itself, and children, indicating access to the entry's children.
       ObjectClass names may also be specified in this list, which will
       affect all the attributes that are required and/or allowed by that
       objectClass.  Actually, names in <attrlist> that are prefixed by @
       are directly treated as objectClass names.  A name prefixed by !  is
       also treated as an objectClass, but in this case the access rule
       affects the attributes that are not required nor allowed by that
       objectClass.  If no attrs form is given, attrs=@extensibleObject is
       implied, i.e. all attributes are addressed.

       Using the form attrs=<attr>
       val[/matchingRule][.<attrstyle>]=<attrval> specifies access to a
       particular value of a single attribute.  In this case, only a single
       attribute type may be given. The <attrstyle> exact (the default) uses
       the attribute's equality matching rule to compare the value, unless a
       different (and compatible) matching rule is specified. If the
       <attrstyle> is regex, the provided value is used as a POSIX
       (''extended'') regular expression pattern.  If the attribute has DN
       syntax, the <attrstyle> can be any of base, onelevel, subtree or
       children, resulting in base, onelevel, subtree or children match,

       The dn, filter, and attrs statements are additive; they can be used
       in sequence to select entities the access rule applies to based on
       naming context, value and attribute type simultaneously.  Submatches
       resulting from regex matching can be dereferenced in the <who> field
       using the syntax ${v<n>}, where <n> is the submatch number.  The
       default syntax, $<n>, is actually an alias for ${d<n>}, that
       corresponds to dereferencing submatches from the dnpattern portion of
       the <what> field.

THE <WHO> FIELD         top

       The field <who> indicates whom the access rules apply to.  Multiple
       <who> statements can appear in an access control statement,
       indicating the different access privileges to the same resource that
       apply to different accessee.  It can have the forms









            <name>=aci          <pattern>=<attrname>]

       They may be specified in combination.

       The wildcard * refers to everybody.

       The keywords prefixed by real act as their counterparts without
       prefix; the checking respectively occurs with the authentication DN
       and the authorization DN.

       The keyword anonymous means access is granted to unauthenticated
       clients; it is mostly used to limit access to authentication
       resources (e.g. the userPassword attribute) to unauthenticated
       clients for authentication purposes.

       The keyword users means access is granted to authenticated clients.

       The keyword self means access to an entry is allowed to the entry
       itself (e.g. the entry being accessed and the requesting entry must
       be the same).  It allows the level{<n>} style, where <n> indicates
       what ancestor of the DN is to be used in matches.  A positive value
       indicates that the <n>-th ancestor of the user's DN is to be
       considered; a negative value indicates that the <n>-th ancestor of
       the target is to be considered.  For example, a "by self.level{1}
       ..." clause would match when the object "dc=example,dc=com" is
       accessed by "cn=User,dc=example,dc=com".  A "by self.level{-1} ..."
       clause would match when the same user accesses the object "ou=Address

       The statement dn=<DN> means that access is granted to the matching
       DN.  The optional style qualifier dnstyle allows the same choices of
       the dn form of the <what> field.  In addition, the regex style can
       exploit substring substitution of submatches in the <what> dn.regex
       clause by using the form $<digit>, with digit ranging from 0 to 9
       (where 0 matches the entire string), or the form ${<digit>+}, for
       submatches higher than 9.  Substring substitution from attribute
       value can be done in using the form ${v<digit>+}.  Since the dollar
       character is used to indicate a substring replacement, the dollar
       character that is used to indicate match up to the end of the string
       must be escaped by a second dollar character, e.g.

           access to dn.regex="^(.+,)?uid=([^,]+),dc=[^,]+,dc=com$"
               by dn.regex="^uid=$2,dc=[^,]+,dc=com$$" write

       The style qualifier allows an optional modifier.  At present, the
       only type allowed is expand, which causes substring substitution of
       submatches to take place even if dnstyle is not regex.  Note that the
       regex dnstyle in the above example may be of use only if the <by>
       clause needs to be a regex; otherwise, if the value of the second
       (from the right) dc= portion of the DN in the above example were
       fixed, the form

           access to dn.regex="^(.+,)?uid=([^,]+),dc=example,dc=com$"
               by dn.exact,expand="uid=$2,dc=example,dc=com" write

       could be used; if it had to match the value in the <what> clause, the

           access to dn.regex="^(.+,)?uid=([^,]+),dc=([^,]+),dc=com$"
               by dn.exact,expand="uid=$2,dc=$3,dc=com" write

       could be used.

       Forms of the <what> clause other than regex may provide submatches as
       well.  The base(object), the sub(tree), the one(level), and the
       children forms provide $0 as the match of the entire string.  The
       sub(tree), the one(level), and the children forms also provide $1 as
       the match of the rightmost part of the DN as defined in the <what>
       clause.  This may be useful, for instance, to provide access to all
       the ancestors of a user by defining

           access to dn.subtree="dc=com"
               by dn.subtree,expand="$1" read

       which means that only access to entries that appear in the DN of the
       <by> clause is allowed.

       The level{<n>} form is an extension and a generalization of the
       onelevel form, which matches all DNs whose <n>-th ancestor is the
       pattern.  So, level{1} is equivalent to onelevel, and level{0} is
       equivalent to base.

       It is perfectly useless to give any access privileges to a DN that
       exactly matches the rootdn of the database the ACLs apply to, because
       it implicitly possesses write privileges for the entire tree of that
       database.  Actually, access control is bypassed for the rootdn, to
       solve the intrinsic chicken-and-egg problem.

       The statement dnattr=<attrname> means that access is granted to
       requests whose DN is listed in the entry being accessed under the
       <attrname> attribute.

       The statement group=<group> means that access is granted to requests
       whose DN is listed in the group entry whose DN is given by <group>.
       The optional parameters <objectclass> and <attrname> define the
       objectClass and the member attributeType of the group entry.  The
       defaults are groupOfNames and member, respectively.  The optional
       style qualifier <style> can be expand, which means that <group> will
       be expanded as a replacement string (but not as a regular expression)
       according to regex(7) and/or re_format(7), and exact, which means
       that exact match will be used.  If the style of the DN portion of the
       <what> clause is regex, the submatches are made available according
       to regex(7) and/or re_format(7); other styles provide limited
       submatches as discussed above about the DN form of the <by> clause.

       For static groups, the specified attributeType must have
       DistinguishedName or NameAndOptionalUID syntax. For dynamic groups
       the attributeType must be a subtype of the labeledURI attributeType.
       Only LDAP URIs of the form ldap:///<base>??<scope>?<filter> will be
       evaluated in a dynamic group, by searching the local server only.

       The statements peername=<peername>, sockname=<sockname>,
       domain=<domain>, and sockurl=<sockurl> mean that the contacting host
       IP (in the form IP=<ip>:<port> for IPv4, or IP=[<ipv6>]:<port> for
       IPv6) or the contacting host named pipe file name (in the form
       PATH=<path> if connecting through a named pipe) for peername, the
       named pipe file name for sockname, the contacting host name for
       domain, and the contacting URL for sockurl are compared against
       pattern to determine access.  The same style rules for pattern match
       described for the group case apply, plus the regex style, which
       implies submatch expand and regex match of the corresponding
       connection parameters.  The exact style of the <peername> clause (the
       default) implies a case-exact match on the client's IP, including the
       IP= prefix and the trailing :<port>, or the client's path, including
       the PATH= prefix if connecting through a named pipe.  The special ip
       style interprets the pattern as <peername>=<ip>[%<mask>][{<n>}],
       where <ip> and <mask> are dotted digit representations of the IP and
       the mask, while <n>, delimited by curly brackets, is an optional
       port.  The same applies to IPv6 addresses when the special ipv6 style
       is used.  When checking access privileges, the IP portion of the
       peername is extracted, eliminating the IP= prefix and the :<port>
       part, and it is compared against the <ip> portion of the pattern
       after masking with <mask>: ((peername & <mask>) == <ip>).  As an
       example, peername.ip= and peername.ipv6=::1 allow
       connections only from localhost,
       peername.ip= allows connections from any IP
       in the 192.168.1 class C domain, and
       peername.ip={9009} allows connections
       from any IP in the 192.168.1.[16-31] range of the same domain, only
       if port 9009 is used.  The special path style eliminates the PATH=
       prefix from the peername when connecting through a named pipe, and
       performs an exact match on the given pattern.  The <domain> clause
       also allows the subtree style, which succeeds when a fully qualified
       name exactly matches the domain pattern, or its trailing part, after
       a dot, exactly matches the domain pattern.  The expand style is
       allowed, implying an exact match with submatch expansion; the use of
       expand as a style modifier is considered more appropriate.  As an
       example, will match, but
       will not match  The domain of the contacting
       host is determined by performing a DNS reverse lookup.  As this
       lookup can easily be spoofed, use of the domain statement is strongly
       discouraged.  By default, reverse lookups are disabled.  The optional
       domainstyle qualifier of the <domain> clause allows a modifier
       option; the only value currently supported is expand, which causes
       substring substitution of submatches to take place even if the
       domainstyle is not regex, much like the analogous usage in <dn>

       The statement set=<pattern> is undocumented yet.

       The statement dynacl/<name>[/<options>][.<dynstyle>][=<pattern>]
       means that access checking is delegated to the admin-defined method
       indicated by <name>, which can be registered at run-time by means of
       the moduleload statement.  The fields <options>, <dynstyle> and
       <pattern> are optional, and are directly passed to the registered
       parsing routine.  Dynacl is experimental; it must be enabled at
       compile time.

       The statement dynacl/aci[=<attrname>] means that the access control
       is determined by the values in the attrname of the entry itself.  The
       optional <attrname> indicates what attributeType holds the ACI
       information in the entry.  By default, the OpenLDAPaci operational
       attribute is used.  ACIs are experimental; they must be enabled at
       compile time.

       The statements ssf=<n>, transport_ssf=<n>, tls_ssf=<n>, and
       sasl_ssf=<n> set the minimum required Security Strength Factor (ssf)
       needed to grant access.  The value should be positive integer.

THE <ACCESS> FIELD         top

       The optional field <access> ::= [[real]self]{<level>|<priv>}
       determines the access level or the specific access privileges the who
       field will have.  Its component are defined as

            <level> ::= none|disclose|auth|compare|search|read|{write|add|delete}|manage
            <priv> ::= {=|+|-}{0|d|x|c|s|r|{w|a|z}|m}+

       The modifier self allows special operations like having a certain
       access level or privilege only in case the operation involves the
       name of the user that's requesting the access.  It implies the user
       that requests access is authorized.  The modifier realself refers to
       the authenticated DN as opposed to the authorized DN of the self
       modifier.  An example is the selfwrite access to the member attribute
       of a group, which allows one to add/delete its own DN from the member
       list of a group, while being not allowed to affect other members.

       The level access model relies on an incremental interpretation of the
       access privileges.  The possible levels are none, disclose, auth,
       compare, search, read, write, and manage.  Each access level implies
       all the preceding ones, thus manage grants all access including
       administrative access.  The write access is actually the combination
       of add and delete, which respectively restrict the write privilege to
       add or delete the specified <what>.

       The none access level disallows all access including disclosure on

       The disclose access level allows disclosure of information on error.

       The auth access level means that one is allowed access to an
       attribute to perform authentication/authorization operations (e.g.
       bind) with no other access.  This is useful to grant unauthenticated
       clients the least possible access level to critical resources, like

       The priv access model relies on the explicit setting of access
       privileges for each clause.  The = sign resets previously defined
       accesses; as a consequence, the final access privileges will be only
       those defined by the clause.  The + and - signs add/remove access
       privileges to the existing ones.  The privileges are m for manage, w
       for write, a for add, z for delete, r for read, s for search, c for
       compare, x for authentication, and d for disclose.  More than one of
       the above privileges can be added in one statement.  0 indicates no
       privileges and is used only by itself (e.g., +0).  Note that +az is
       equivalent to +w.

       If no access is given, it defaults to +0.

THE <CONTROL> FIELD         top

       The optional field <control> controls the flow of access rule
       application.  It can have the forms


       where stop, the default, means access checking stops in case of
       match.  The other two forms are used to keep on processing access
       clauses.  In detail, the continue form allows for other <who> clauses
       in the same <access> clause to be considered, so that they may result
       in incrementally altering the privileges, while the break form allows
       for other <access> clauses that match the same target to be
       processed.  Consider the (silly) example

            access to dn.subtree="dc=example,dc=com" attrs=cn
                 by * =cs break

            access to dn.subtree="ou=People,dc=example,dc=com"
                 by * +r

       which allows search and compare privileges to everybody under the
       "dc=example,dc=com" tree, with the second rule allowing also read in
       the "ou=People" subtree, or the (even more silly) example

            access to dn.subtree="dc=example,dc=com" attrs=cn
                 by * =cs continue
                 by users +r

       which grants everybody search and compare privileges, and adds read
       privileges to authenticated clients.

       One useful application is to easily grant write privileges to an
       updatedn that is different from the rootdn.  In this case, since the
       updatedn needs write access to (almost) all data, one can use

            access to *
                 by dn.exact="cn=The Update DN,dc=example,dc=com" write
                 by * break

       as the first access rule.  As a consequence, unless the operation is
       performed with the updatedn identity, control is passed straight to
       the subsequent rules.


       Operations require different privileges on different portions of
       entries.  The following summary applies to primary MDB database
       backend. Requirements for other backends may (and often do) differ.

       The add operation requires add (=a) privileges on the pseudo-
       attribute entry of the entry being added, and add (=a) privileges on
       the pseudo-attribute children of the entry's parent.  When adding the
       suffix entry of a database, add access to children of the empty DN
       ("") is required. Also if Add content ACL checking has been
       configured on the database (see the slapd.conf(5) or slapd-config(5)
       manual page), add (=a) will be required on all of the attributes
       being added.

       The bind operation, when credentials are stored in the directory,
       requires auth (=x) privileges on the attribute the credentials are
       stored in (usually userPassword).

       The compare operation requires compare (=c) privileges on the
       attribute that is being compared.

       The delete operation requires delete (=z) privileges on the pseudo-
       attribute entry of the entry being deleted, and delete (=d)
       privileges on the children pseudo-attribute of the entry's parent.

       The modify operation requires write (=w) privileges on the attributes
       being modified.  In detail, add (=a) is required to add new values,
       delete (=z) is required to delete existing values, and both delete
       and add (=az), or write (=w), are required to replace existing

       The modrdn operation requires write (=w) privileges on the pseudo-
       attribute entry of the entry whose relative DN is being modified,
       delete (=z) privileges on the pseudo-attribute children of the old
       entry's parents, add (=a) privileges on the pseudo-attribute children
       of the new entry's parents, and add (=a) privileges on the attributes
       that are present in the new relative DN.  Delete (=z) privileges are
       also required on the attributes that are present in the old relative
       DN if deleteoldrdn is set to 1.

       The search operation, requires search (=s) privileges on the entry
       pseudo-attribute of the searchBase (NOTE: this was introduced with
       OpenLDAP 2.4).  Then, for each entry, it requires search (=s)
       privileges on the attributes that are defined in the filter.  The
       resulting entries are finally tested for read (=r) privileges on the
       pseudo-attribute entry (for read access to the entry itself) and for
       read (=r) access on each value of each attribute that is requested.
       Also, for each referral object used in generating continuation
       references, the operation requires read (=r) access on the pseudo-
       attribute entry (for read access to the referral object itself), as
       well as read (=r) access to the attribute holding the referral
       information (generally the ref attribute).

       Some internal operations and some controls require specific access
       privileges.  The authzID mapping and the proxyAuthz control require
       auth (=x) privileges on all the attributes that are present in the
       search filter of the URI regexp maps (the right-hand side of the
       authz-regexp directives).  Auth (=x) privileges are also required on
       the authzTo attribute of the authorizing identity and/or on the
       authzFrom attribute of the authorized identity.  In general, when an
       internal lookup is performed for authentication or authorization
       purposes, search-specific privileges (see the access requirements for
       the search operation illustrated above) are relaxed to auth.

       Access control to search entries is checked by the frontend, so it is
       fully honored by all backends; for all other operations and for the
       discovery phase of the search operation, full ACL semantics is only
       supported by the primary backends, i.e.  back-mdb(5).

       Some other backend, like back-sql(5), may fully support them; others
       may only support a portion of the described semantics, or even differ
       in some aspects.  The relevant details are described in the backend-
       specific man pages.

CAVEATS         top

       It is strongly recommended to explicitly use the most appropriate
       <dnstyle> in <what> and <who> clauses, to avoid possible incorrect
       specifications of the access rules as well as for performance (avoid
       unnecessary regex matching when an exact match suffices) reasons.

       An administrator might create a rule of the form:

            access to dn.regex="dc=example,dc=com"
                 by ...

       expecting it to match all entries in the subtree "dc=example,dc=com".
       However, this rule actually matches any DN which contains anywhere
       the substring "dc=example,dc=com".  That is, the rule matches both
       "uid=joe,dc=example,dc=com" and "dc=example,dc=com,uid=joe".

       To match the desired subtree, the rule would be more precisely

            access to dn.regex="^(.+,)?dc=example,dc=com$"
                 by ...

       For performance reasons, it would be better to use the subtree style.

            access to dn.subtree="dc=example,dc=com"
                 by ...

       When writing submatch rules, it may be convenient to avoid
       unnecessary regex <dnstyle> use; for instance, to allow access to the
       subtree of the user that matches the <what> clause, one could use

            access to dn.regex="^(.+,)?uid=([^,]+),dc=example,dc=com$"
                 by dn.regex="^uid=$2,dc=example,dc=com$$" write
                 by ...

       However, since all that is required in the <by> clause is substring
       expansion, a more efficient solution is

            access to dn.regex="^(.+,)?uid=([^,]+),dc=example,dc=com$"
                 by dn.exact,expand="uid=$2,dc=example,dc=com" write
                 by ...

       In fact, while a <dnstyle> of regex implies substring expansion,
       exact, as well as all the other DN specific <dnstyle> values, does
       not, so it must be explicitly requested.

FILES         top

              default slapd configuration file

SEE ALSO         top

       slapd(8), slapd-*(5), slapacl(8), regex(7), re_format(7)

       "OpenLDAP Administrator's Guide" (


       OpenLDAP Software is developed and maintained by The OpenLDAP Project
       <>.  OpenLDAP Software is derived from the
       University of Michigan LDAP 3.3 Release.

COLOPHON         top

       This page is part of the OpenLDAP (an open source implementation of
       the Lightweight Directory Access Protocol) project.  Information
       about the project can be found at ⟨⟩.  If you
       have a bug report for this manual page, see
       ⟨⟩.  This page was obtained from the
       project's upstream Git repository
       ⟨⟩ on 2020-11-01.  (At
       that time, the date of the most recent commit that was found in the
       repository was 2020-10-30.)  If you discover any rendering problems
       in this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or im‐
       provements to the information in this COLOPHON (which is not part of
       the original manual page), send a mail to

OpenLDAP LDVERSION               RELEASEDATE                 SLAPD.ACCESS(5)

Pages that refer to this page: slapd-asyncmeta(5)slapd.conf(5)slapd-config(5)slapd-dnssrv(5)slapd-ldap(5)slapd-ldif(5)slapd-mdb(5)slapd-meta(5)slapd-monitor(5)slapd-ndb(5)slapd-null(5)slapd-passwd(5)slapd-perl(5)slapd-relay(5)slapd-shell(5)slapd-sock(5)slapd-sql(5)slapd-wt(5)slapo-dds(5)slapo-ppolicy(5)slapo-sock(5)slapacl(8)slapd(8)