2 # Copyright 2007-2008 The OpenLDAP Foundation, All Rights Reserved.
3 # COPYING RESTRICTIONS APPLY, see COPYRIGHT.
7 Overlays are software components that provide hooks to functions analogous to
8 those provided by backends, which can be stacked on top of the backend calls
9 and as callbacks on top of backend responses to alter their behavior.
11 Overlays may be compiled statically into {{slapd}}, or when module support
12 is enabled, they may be dynamically loaded. Most of the overlays
13 are only allowed to be configured on individual databases, but some
14 may also be configured globally.
16 Essentially, they represent a means to:
18 * customize the behavior of existing backends without changing the backend
19 code and without requiring one to write a new custom backend with
20 complete functionality
21 * write functionality of general usefulness that can be applied to
22 different backend types
24 Overlays are usually documented by separate specific man pages in section 5;
25 the naming convention is
27 > slapo-<overlay name>
29 All distributed core overlays have a man page. Feel free to contribute to any,
30 if you think there is anything missing in describing the behavior of the component
31 and the implications of all the related configuration directives.
33 Official overlays are located in
35 > servers/slapd/overlays/
37 That directory also contains the file slapover.txt, which describes the
38 rationale of the overlay implementation, and may serve as guideline for the
39 development of custom overlays.
41 Contribware overlays are located in
43 > contrib/slapd-modules/<overlay name>/
45 along with other types of run-time loadable components; they are officially
46 distributed, but not maintained by the project.
48 They can be stacked on the frontend as well; this means that they can be
49 executed after a request is parsed and validated, but right before the
50 appropriate database is selected. The main purpose is to affect operations
51 regardless of the database they will be handled by, and, in some cases,
52 to influence the selection of the database by massaging the request DN.
54 All the current overlays in 2.4 are listed and described in detail in the
63 This overlay can record accesses to a given backend database on another
66 This allows all of the activity on a given database to be reviewed using arbitrary
67 LDAP queries, instead of just logging to local flat text files. Configuration
68 options are available for selecting a subset of operation types to log, and to
69 automatically prune older log records from the logging database. Log records
70 are stored with audit schema to assure their readability whether viewed as LDIF
73 It is also used for {{SECT:delta-syncrepl replication}}
75 H3: Access Logging Configuration
77 The following is a basic example that implements Access Logging:
80 > suffix dc=example,dc=com
85 > logold (objectclass=person)
92 > by dn.base="cn=admin,dc=example,dc=com" read
94 The following is an example used for {{SECT:delta-syncrepl replication}}:
98 > directory /usr/local/var/openldap-accesslog
101 > index entryCSN,objectClass,reqEnd,reqResult,reqStart
103 Accesslog overlay definitions for the primary db
106 > suffix dc=example,dc=com
112 > # scan the accesslog DB every day, and purge entries older than 7 days
113 > logpurge 07+00:00 01+00:00
115 An example search result against {{B:cn=accesslog}} might look like:
117 > [ghenry@suretec ghenry]# ldapsearch -x -b cn=accesslog
121 > # base <cn=accesslog> with scope subtree
122 > # filter: (objectclass=*)
128 > objectClass: auditContainer
131 > # 20080110163829.000004Z, accesslog
132 > dn: reqStart=20080110163829.000004Z,cn=accesslog
133 > objectClass: auditModify
134 > reqStart: 20080110163829.000004Z
135 > reqEnd: 20080110163829.000005Z
138 > reqAuthzID: cn=admin,dc=suretecsystems,dc=com
139 > reqDN: uid=suretec-46022f8$,ou=Users,dc=suretecsystems,dc=com
141 > reqMod: sambaPwdCanChange:- ###CENSORED###
142 > reqMod: sambaPwdCanChange:+ ###CENSORED###
143 > reqMod: sambaNTPassword:- ###CENSORED###
144 > reqMod: sambaNTPassword:+ ###CENSORED###
145 > reqMod: sambaPwdLastSet:- ###CENSORED###
146 > reqMod: sambaPwdLastSet:+ ###CENSORED###
147 > reqMod: entryCSN:= 20080110163829.095157Z#000000#000#000000
148 > reqMod: modifiersName:= cn=admin,dc=suretecsystems,dc=com
149 > reqMod: modifyTimestamp:= 20080110163829Z
158 For more information, please see {{slapo-accesslog(5)}} and the {{SECT:delta-syncrepl replication}} section.
163 The Audit Logging overlay can be used to record all changes on a given backend database to a specified log file.
167 If the need arises whereby changes need to be logged as standard LDIF, then the auditlog overlay {{B:slapo-auditlog (5)}}
168 can be used. Full examples are available in the man page {{B:slapo-auditlog (5)}}
170 H3: Audit Logging Configuration
172 If the directory is running vi {{F:slapd.d}}, then the following LDIF could be used to add the overlay to the overlay list
173 in {{B:cn=config}} and set what file the {{TERM:LDIF}} gets logged to (adjust to suit)
175 > dn: olcOverlay=auditlog,olcDatabase={1}hdb,cn=config
177 > objectClass: olcOverlayConfig
178 > objectClass: olcAuditLogConfig
179 > olcOverlay: auditlog
180 > olcAuditlogFile: /tmp/auditlog.ldif
183 In this example for testing, we are logging changes to {{F:/tmp/auditlog.ldif}}
185 A typical {{TERM:LDIF}} file created by {{B:slapo-auditlog (5)}} would look like:
187 > # add 1196797576 dc=suretecsystems,dc=com cn=admin,dc=suretecsystems,dc=com
188 > dn: dc=suretecsystems,dc=com
190 > objectClass: dcObject
191 > objectClass: organization
193 > o: Suretec Systems Ltd.
194 > structuralObjectClass: organization
195 > entryUUID: 1606f8f8-f06e-1029-8289-f0cc9d81e81a
196 > creatorsName: cn=admin,dc=suretecsystems,dc=com
197 > modifiersName: cn=admin,dc=suretecsystems,dc=com
198 > createTimestamp: 20051123130912Z
199 > modifyTimestamp: 20051123130912Z
200 > entryCSN: 20051123130912.000000Z#000001#000#000000
201 > auditContext: cn=accesslog
202 > # end add 1196797576
204 > # add 1196797577 dc=suretecsystems,dc=com cn=admin,dc=suretecsystems,dc=com
205 > dn: ou=Groups,dc=suretecsystems,dc=com
208 > objectClass: organizationalUnit
210 > structuralObjectClass: organizationalUnit
211 > entryUUID: 160aaa2a-f06e-1029-828a-f0cc9d81e81a
212 > creatorsName: cn=admin,dc=suretecsystems,dc=com
213 > modifiersName: cn=admin,dc=suretecsystems,dc=com
214 > createTimestamp: 20051123130912Z
215 > modifyTimestamp: 20051123130912Z
216 > entryCSN: 20051123130912.000000Z#000002#000#000000
217 > # end add 1196797577
225 The chain overlay provides basic chaining capability to the underlying
228 What is chaining? It indicates the capability of a DSA to follow referrals on
229 behalf of the client, so that distributed systems are viewed as a single
230 virtual DSA by clients that are otherwise unable to "chase" (i.e. follow)
231 referrals by themselves.
233 The chain overlay is built on top of the ldap backend; it is compiled by
234 default when {{B:--enable-ldap}}.
237 H3: Chaining Configuration
239 In order to demonstrate how this overlay works, we shall discuss a typical
240 scenario which might be one master server and three Syncrepl slaves.
242 On each replica, add this near the top of the file (global), before any database
246 > chain-uri "ldap://ldapmaster.example.com"
247 > chain-idassert-bind bindmethod="simple"
248 > binddn="cn=Manager,dc=example,dc=com"
249 > credentials="<secret>"
252 > chain-return-error TRUE
254 Add this below your {{syncrepl}} statement:
256 > updateref "ldap://ldapmaster.example.com/"
258 The {{B:chain-tls}} statement enables TLS from the slave to the ldap master.
259 The DITs are exactly the same between these machines, therefore whatever user
260 bound to the slave will also exist on the master. If that DN does not have
261 update privileges on the master, nothing will happen.
263 You will need to restart the slave after these changes. Then, if you are using
264 {{loglevel stats}} (256), you can monitor an {{ldapmodify}} on the slave and the master.
266 Now start an {{ldapmodify}} on the slave and watch the logs. You should expect
269 > Sep 6 09:27:25 slave1 slapd[29274]: conn=11 fd=31 ACCEPT from IP=143.199.102.216:45181 (IP=143.199.102.216:389)
270 > Sep 6 09:27:25 slave1 slapd[29274]: conn=11 op=0 STARTTLS
271 > Sep 6 09:27:25 slave1 slapd[29274]: conn=11 op=0 RESULT oid= err=0 text=
272 > Sep 6 09:27:25 slave1 slapd[29274]: conn=11 fd=31 TLS established tls_ssf=256 ssf=256
273 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=1 BIND dn="uid=user1,ou=people,dc=example,dc=com" method=128
274 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=1 BIND dn="uid=user1,ou=People,dc=example,dc=com" mech=SIMPLE ssf=0
275 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=1 RESULT tag=97 err=0 text=
276 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=2 MOD dn="uid=user1,ou=People,dc=example,dc=com"
277 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=2 MOD attr=mail
278 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=2 RESULT tag=103 err=0 text=
279 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=3 UNBIND
280 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 fd=31 closed
281 > Sep 6 09:27:28 slave1 slapd[29274]: syncrepl_entry: LDAP_RES_SEARCH_ENTRY(LDAP_SYNC_MODIFY)
282 > Sep 6 09:27:28 slave1 slapd[29274]: syncrepl_entry: be_search (0)
283 > Sep 6 09:27:28 slave1 slapd[29274]: syncrepl_entry: uid=user1,ou=People,dc=example,dc=com
284 > Sep 6 09:27:28 slave1 slapd[29274]: syncrepl_entry: be_modify (0)
286 And on the master you will see this:
288 > Sep 6 09:23:57 ldapmaster slapd[2961]: conn=55902 op=3 PROXYAUTHZ dn="uid=user1,ou=people,dc=example,dc=com"
289 > Sep 6 09:23:57 ldapmaster slapd[2961]: conn=55902 op=3 MOD dn="uid=user1,ou=People,dc=example,dc=com"
290 > Sep 6 09:23:57 ldapmaster slapd[2961]: conn=55902 op=3 MOD attr=mail
291 > Sep 6 09:23:57 ldapmaster slapd[2961]: conn=55902 op=3 RESULT tag=103 err=0 text=
293 Note: You can clearly see the PROXYAUTHZ line on the master, indicating the
294 proper identity assertion for the update on the master. Also note the slave
295 immediately receiving the Syncrepl update from the master.
297 H3: Handling Chaining Errors
299 By default, if chaining fails, the original referral is returned to the client
300 under the assumption that the client might want to try and follow the referral.
302 With the following directive however, if the chaining fails at the provider
303 side, the actual error is returned to the client.
305 > chain-return-error TRUE
313 This overlay enforces a regular expression constraint on all values
314 of specified attributes during an LDAP modify request that contains add or modify
315 commands. It is used to enforce a more rigorous syntax when the underlying attribute
316 syntax is too general.
319 H3: Constraint Configuration
321 Configuration via {{slapd.conf}}(5) would look like:
324 > constraint_attribute mail regex ^[:alnum:]+@mydomain.com$
325 > constraint_attribute title uri
326 > ldap:///dc=catalog,dc=example,dc=com?title?sub?(objectClass=titleCatalog)
328 A specification like the above would reject any {{mail}} attribute which did not
329 look like {{<alpha-numeric string>@mydomain.com}}.
331 It would also reject any title attribute whose values were not listed in the
332 title attribute of any {{titleCatalog}} entries in the given scope.
334 An example for use with {{cn=config}}:
336 > dn: olcOverlay=constraint,olcDatabase={1}hdb,cn=config
338 > objectClass: olcOverlayConfig
339 > objectClass: olcConstraintConfig
340 > olcOverlay: constraint
341 > olcConstraintAttribute: mail regex ^[:alnum:]+@mydomain.com$
342 > olcConstraintAttribute: title uri ldap:///dc=catalog,dc=example,dc=com?title?sub?(objectClass=titleCatalog)
345 H2: Dynamic Directory Services
350 The {{dds}} overlay to {{slapd}}(8) implements dynamic objects as per RFC 2589.
351 The name {{dds}} stands for Dynamic Directory Services. It allows to define
352 dynamic objects, characterized by the {{dynamicObject}} objectClass.
354 Dynamic objects have a limited lifetime, determined by a time-to-live (TTL)
355 that can be refreshed by means of a specific refresh extended operation. This
356 operation allows to set the Client Refresh Period (CRP), namely the period
357 between refreshes that is required to preserve the dynamic object from expiration.
358 The expiration time is computed by adding the requested TTL to the current time.
359 When dynamic objects reach the end of their lifetime without being further
360 refreshed, they are automatically {{deleted}}. There is no guarantee of immediate
361 deletion, so clients should not count on it.
363 Dynamic objects can have subordinates, provided these also are dynamic objects.
364 RFC 2589 does not specify what the behavior of a dynamic directory service
365 should be when a dynamic object with (dynamic) subordinates expires.
366 In this implementation, the lifetime of dynamic objects with subordinates is prolonged
367 until all the dynamic subordinates expire.
369 H3: Dynamic Directory Service Configuration
377 This overlay extends the Compare operation to detect
378 members of a dynamic group. This overlay is now deprecated
379 as all of its functions are available using the
380 {{SECT:Dynamic Lists}} overlay.
383 H3: Dynamic Group Configuration
391 This overlay allows expansion of dynamic groups and lists. Instead of having the
392 group members or list attributes hard coded, this overlay allows us to define
393 an LDAP search whose results will make up the group or list.
395 H3: Dynamic List Configuration
397 This module can behave both as a dynamic list and dynamic group, depending on
398 the configuration. The syntax is as follows:
401 > dynlist-attrset <group-oc> <URL-ad> [member-ad]
403 The parameters to the {{F:dynlist-attrset}} directive have the following meaning:
404 * {{F:<group-oc>}}: specifies which object class triggers the subsequent LDAP search.
405 Whenever an entry with this object class is retrieved, the search is performed.
406 * {{F:<URL-ad>}}: is the name of the attribute which holds the search URI. It
407 has to be a subtype of {{F:labeledURI}}. The attributes and values present in
408 the search result are added to the entry unless {{F:member-ad}} is used (see
410 * {{F:member-ad}}: if present, changes the overlay behavior into a dynamic group.
411 Instead of inserting the results of the search in the entry, the distinguished name
412 of the results are added as values of this attribute.
414 Here is an example which will allow us to have an email alias which automatically
415 expands to all user's emails according to our LDAP filter:
417 In {{slapd.conf}}(5):
419 > dynlist-attrset nisMailAlias labeledURI
421 This means that whenever an entry which has the {{F:nisMailAlias}} object class is
422 retrieved, the search specified in the {{F:labeledURI}} attribute is performed.
424 Let's say we have this entry in our directory:
425 > cn=all,ou=aliases,dc=example,dc=com
427 > objectClass: nisMailAlias
428 > labeledURI: ldap:///ou=People,dc=example,dc=com?mail?one?(objectClass=inetOrgPerson)
430 If this entry is retrieved, the search specified in {{F:labeledURI}} will be
431 performed and the results will be added to the entry just as if they have always
432 been there. In this case, the search filter selects all entries directly
433 under {{F:ou=People}} that have the {{F:inetOrgPerson}} object class and retrieves
434 the {{F:mail}} attribute, if it exists.
436 This is what gets added to the entry when we have two users under {{F:ou=People}}
437 that match the filter:
438 !import "allmail-en.png"; align="center"; title="Dynamic list for email aliases"
439 FT[align="Center"] Figure X.Y: Dynamic List for all emails
441 The configuration for a dynamic group is similar. Let's see an example which would
442 automatically populate an {{F:allusers}} group with all the user accounts in the
445 In {{F:slapd.conf}}(5):
447 > dynlist-attrset groupOfNames labeledURI member
449 Let's apply it to the following entry:
450 > cn=allusers,ou=group,dc=example,dc=com
452 > objectClass: groupOfNames
453 > labeledURI: ldap:///ou=people,dc=example,dc=com??one?(objectClass=inetOrgPerson)
455 The behavior is similar to the dynamic list configuration we had before:
456 whenever an entry with the {{F:groupOfNames}} object class is retrieved, the
457 search specified in the {{F:labeledURI}} attribute is performed. But this time,
458 only the distinguished names of the results are added, and as values of the
459 {{F:member}} attribute.
462 !import "allusersgroup-en.png"; align="center"; title="Dynamic group for all users"
463 FT[align="Center"] Figure X.Y: Dynamic Group for all users
465 Note that a side effect of this scheme of dynamic groups is that the members
466 need to be specified as full DNs. So, if you are planning in using this for
467 {{F:posixGroup}}s, be sure to use RFC2307bis and some attribute which can hold
468 distinguished names. The {{F:memberUid}} attribute used in the {{F:posixGroup}}
469 object class can hold only names, not DNs, and is therefore not suitable for
472 H2: Reverse Group Membership Maintenance
476 In some scenarios, it may be desirable for a client to be able to determine
477 which groups an entry is a member of, without performing an additional search.
478 Examples of this are applications using the {{TERM:DIT}} for access control
479 based on group authorization.
481 The {{B:memberof}} overlay updates an attribute (by default {{B:memberOf}}) whenever
482 changes occur to the membership attribute (by default {{B:member}}) of entries of the
483 objectclass (by default {{B:groupOfNames}}) configured to trigger updates.
485 Thus, it provides maintenance of the list of groups an entry is a member of,
486 when usual maintenance of groups is done by modifying the members on the group
489 H3: Member Of Configuration
491 The typical use of this overlay requires just enabling the overlay for a
492 specific database. For example, with the following minimal slapd.conf:
494 > include /usr/share/openldap/schema/core.schema
495 > include /usr/share/openldap/schema/cosine.schema
496 > modulepath /usr/lib/openldap
497 > moduleload memberof.la
498 > authz-regexp "gidNumber=0\\\+uidNumber=0,cn=peercred,cn=external,cn=auth"
499 > "cn=Manager,dc=example,dc=com"
501 > suffix "dc=example,dc=com"
502 > rootdn "cn=Manager,dc=example,dc=com"
504 > directory /var/lib/ldap2.4
506 > index objectClass eq
511 adding the following ldif:
514 > dn: dc=example,dc=com
515 > objectclass: domain
518 > dn: ou=Group,dc=example,dc=com
519 > objectclass: organizationalUnit
522 > dn: ou=People,dc=example,dc=com
523 > objectclass: organizationalUnit
526 > dn: uid=test1,ou=People,dc=example,dc=com
527 > objectclass: account
530 > dn: cn=testgroup,ou=Group,dc=example,dc=com
531 > objectclass: groupOfNames
533 > member: uid=test1,ou=People,dc=example,dc=com
535 Results in the following output from a search on the test1 user:
537 > # ldapsearch -LL -Y EXTERNAL -H ldapi:/// "(uid=test1)" -b dc=example,dc=com memberOf
538 > SASL/EXTERNAL authentication started
539 > SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
543 > dn: uid=test1,ou=People,dc=example,dc=com
544 > memberOf: cn=testgroup,ou=Group,dc=example,dc=com
546 Note that the {{B:memberOf}} attribute is an operational attribute, so it must be
547 requested explicitly.
550 H2: The Proxy Cache Engine
552 {{TERM:LDAP}} servers typically hold one or more subtrees of a
553 {{TERM:DIT}}. Replica (or shadow) servers hold shadow copies of
554 entries held by one or more master servers. Changes are propagated
555 from the master server to replica (slave) servers using LDAP Sync
556 replication. An LDAP cache is a special type of replica which holds
557 entries corresponding to search filters instead of subtrees.
561 The proxy cache extension of slapd is designed to improve the
562 responsiveness of the ldap and meta backends. It handles a search
564 by first determining whether it is contained in any cached search
565 filter. Contained requests are answered from the proxy cache's local
566 database. Other requests are passed on to the underlying ldap or
567 meta backend and processed as usual.
569 E.g. {{EX:(shoesize>=9)}} is contained in {{EX:(shoesize>=8)}} and
570 {{EX:(sn=Richardson)}} is contained in {{EX:(sn=Richards*)}}
572 Correct matching rules and syntaxes are used while comparing
573 assertions for query containment. To simplify the query containment
574 problem, a list of cacheable "templates" (defined below) is specified
575 at configuration time. A query is cached or answered only if it
576 belongs to one of these templates. The entries corresponding to
577 cached queries are stored in the proxy cache local database while
578 its associated meta information (filter, scope, base, attributes)
579 is stored in main memory.
581 A template is a prototype for generating LDAP search requests.
582 Templates are described by a prototype search filter and a list of
583 attributes which are required in queries generated from the template.
584 The representation for prototype filter is similar to {{REF:RFC4515}},
585 except that the assertion values are missing. Examples of prototype
586 filters are: (sn=),(&(sn=)(givenname=)) which are instantiated by
587 search filters (sn=Doe) and (&(sn=Doe)(givenname=John)) respectively.
589 The cache replacement policy removes the least recently used (LRU)
590 query and entries belonging to only that query. Queries are allowed
591 a maximum time to live (TTL) in the cache thus providing weak
592 consistency. A background task periodically checks the cache for
593 expired queries and removes them.
595 The Proxy Cache paper
596 ({{URL:http://www.openldap.org/pub/kapurva/proxycaching.pdf}}) provides
597 design and implementation details.
600 H3: Proxy Cache Configuration
602 The cache configuration specific directives described below must
603 appear after a {{EX:overlay proxycache}} directive within a
604 {{EX:"database meta"}} or {{EX:database ldap}} section of
605 the server's {{slapd.conf}}(5) file.
607 H4: Setting cache parameters
609 > proxyCache <DB> <maxentries> <nattrsets> <entrylimit> <period>
611 This directive enables proxy caching and sets general cache
612 parameters. The <DB> parameter specifies which underlying database
613 is to be used to hold cached entries. It should be set to
614 {{EX:bdb}} or {{EX:hdb}}. The <maxentries> parameter specifies the
615 total number of entries which may be held in the cache. The
616 <nattrsets> parameter specifies the total number of attribute sets
617 (as specified by the {{EX:proxyAttrSet}} directive) that may be
618 defined. The <entrylimit> parameter specifies the maximum number of
619 entries in a cacheable query. The <period> specifies the consistency
620 check period (in seconds). In each period, queries with expired
623 H4: Defining attribute sets
625 > proxyAttrset <index> <attrs...>
627 Used to associate a set of attributes to an index. Each attribute
628 set is associated with an index number from 0 to <numattrsets>-1.
629 These indices are used by the proxyTemplate directive to define
632 H4: Specifying cacheable templates
634 > proxyTemplate <prototype_string> <attrset_index> <TTL>
636 Specifies a cacheable template and the "time to live" (in sec) <TTL>
637 for queries belonging to the template. A template is described by
638 its prototype filter string and set of required attributes identified
644 An example {{slapd.conf}}(5) database section for a caching server
645 which proxies for the {{EX:"dc=example,dc=com"}} subtree held
646 at server {{EX:ldap.example.com}}.
649 > suffix "dc=example,dc=com"
650 > rootdn "dc=example,dc=com"
651 > uri ldap://ldap.example.com/
653 > proxycache bdb 100000 1 1000 100
654 > proxyAttrset 0 mail postaladdress telephonenumber
655 > proxyTemplate (sn=) 0 3600
656 > proxyTemplate (&(sn=)(givenName=)) 0 3600
657 > proxyTemplate (&(departmentNumber=)(secretary=*)) 0 3600
660 > directory ./testrun/db.2.a
661 > index objectClass eq
662 > index cn,sn,uid,mail pres,eq,sub
665 H5: Cacheable Queries
667 A LDAP search query is cacheable when its filter matches one of the
668 templates as defined in the "proxyTemplate" statements and when it references
669 only the attributes specified in the corresponding attribute set.
670 In the example above the attribute set number 0 defines that only the
671 attributes: {{EX:mail postaladdress telephonenumber}} are cached for the following
676 > Filter: (&(sn=Richard*)(givenName=jack))
677 > Attrs: mail telephoneNumber
679 is cacheable, because it matches the template {{EX:(&(sn=)(givenName=))}} and its
680 attributes are contained in proxyAttrset 0.
682 > Filter: (&(sn=Richard*)(telephoneNumber))
685 is not cacheable, because the filter does not match the template,
686 nor is the attribute givenName stored in the cache
688 > Filter: (|(sn=Richard*)(givenName=jack))
689 > Attrs: mail telephoneNumber
691 is not cacheable, because the filter does not match the template ( logical
692 OR "|" condition instead of logical AND "&" )
695 H2: Password Policies
700 This overlay provides a variety of password control mechanisms,
701 e.g. password aging, password reuse and duplication control, mandatory
702 password resets, etc.
705 H3: Password Policy Configuration
708 H2: Referential Integrity
713 This overlay can be used with a backend database such as slapd-bdb(5)
714 to maintain the cohesiveness of a schema which utilizes reference
717 Whenever a {{modrdn}} or {{delete}} is performed, that is, when an entry's DN
718 is renamed or an entry is removed, the server will search the directory for
719 references to this DN (in selected attributes: see below) and update them
720 accordingly. If it was a {{delete}} operation, the reference is deleted. If it
721 was a {{modrdn}} operation, then the reference is updated with the new DN.
723 For example, a very common administration task is to maintain group membership
724 lists, specially when users are removed from the directory. When an
725 user account is deleted or renamed, all groups this user is a member of have to be
726 updated. LDAP administrators usually have scripts for that. But we can use the
727 {{F:refint}} overlay to automate this task. In this example, if the user is
728 removed from the directory, the overlay will take care to remove the user from
729 all the groups he/she was a member of. No more scripting for this.
731 H3: Referential Integrity Configuration
733 The configuration for this overlay is as follows:
735 > refint_attributes <attribute [attribute ...]>
736 > refint_nothing <string>
738 * {{F:refint_attributes}}: this parameter specifies a space separated list of
739 attributes which will have the referential integrity maintained. When an entry is
740 removed or has its DN renamed, the server will do an internal search for any of the
741 {{F:refint_attributes}} that point to the affected DN and update them accordingly. IMPORTANT:
742 the attributes listed here must have the {{F:distinguishedName}} syntax, that is,
744 * {{F:refint_nothing}}: some times, while trying to maintain the referential
745 integrity, the server has to remove the last attribute of its kind from an
746 entry. This may be prohibited by the schema: for example, the
747 {{F:groupOfNames}} object class requires at least one member. In these cases,
748 the server will add the attribute value specified in {{F:refint_nothing}}
751 To illustrate this overlay, we will use the group membership scenario.
755 > refint_attributes member
756 > refint_nothing "cn=admin,dc=example,dc=com"
758 This configuration tells the overlay to maintain the referential integrity of the {{F:member}}
759 attribute. This attribute is used in the {{F:groupOfNames}} object class which always needs
760 a member, so we add the {{F:refint_nothing}} directive to fill in the group with a standard
761 member should all the members vanish.
763 If we have the following group membership, the refint overlay will
764 automatically remove {{F:john}} from the group if his entry is removed from the
767 !import "refint.png"; align="center"; title="Group membership"
768 FT[align="Center"] Figure X.Y: Maintaining referential integrity in groups
770 Notice that if we rename ({{F:modrdn}}) the {{F:john}} entry to, say, {{F:jsmith}}, the refint
771 overlay will also rename the reference in the {{F:member}} attribute, so the group membership
774 If we removed all users from the directory who are a member of this group, then the end result
775 would be a single member in the group: {{F:cn=admin,dc=example,dc=com}}. This is the
776 {{F:refint_nothing}} parameter kicking into action so that the schema is not violated.
783 This overlay is useful to test the behavior of clients when
784 server-generated erroneous and/or unusual responses occur.
787 H3: Return Code Configuration
795 It performs basic DN/data rewrite and
796 objectClass/attributeType mapping.
799 H3: Rewrite/Remap Configuration
807 This overlay implements the provider-side support for syncrepl
808 replication, including persistent search functionality
811 H3: Sync Provider Configuration
814 H2: Translucent Proxy
819 This overlay can be used with a backend database such as slapd-bdb (5)
820 to create a "translucent proxy".
822 Content of entries retrieved from a remote LDAP server can be partially
823 overridden by the database.
826 H3: Translucent Proxy Configuration
829 H2: Attribute Uniqueness
834 This overlay can be used with a backend database such as slapd-bdb (5)
835 to enforce the uniqueness of some or all attributes within a subtree.
838 H3: Attribute Uniqueness Configuration
846 This overlay can be used to enforce a specific order for the values
847 of an attribute when it is returned in a search.
850 H3: Value Sorting Configuration
859 H3: Example Scenarios