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.
15 Some can be stacked on the {{EX:frontend}} as well, for global use. This means that
16 they can be executed after a request is parsed and validated, but right before the
17 appropriate database is selected. The main purpose is to affect operations
18 regardless of the database they will be handled by, and, in some cases,
19 to influence the selection of the database by massaging the request DN.
21 Essentially, overlays represent a means to:
23 * customize the behavior of existing backends without changing the backend
24 code and without requiring one to write a new custom backend with
25 complete functionality
26 * write functionality of general usefulness that can be applied to
27 different backend types
29 When using {{slapd.conf}}(5), overlays that are configured before any other
30 databases are considered global, as mentioned above. In fact they are implicitly
31 stacked on top of the {{EX:frontend}} database. They can also be explicitly
35 > overlay <overlay name>
37 Overlays are usually documented by separate specific man pages in section 5;
38 the naming convention is
40 > slapo-<overlay name>
42 All distributed core overlays have a man page. Feel free to contribute to any,
43 if you think there is anything missing in describing the behavior of the component
44 and the implications of all the related configuration directives.
46 Official overlays are located in
48 > servers/slapd/overlays/
50 That directory also contains the file slapover.txt, which describes the
51 rationale of the overlay implementation, and may serve as a guideline for the
52 development of custom overlays.
54 Contribware overlays are located in
56 > contrib/slapd-modules/<overlay name>/
58 along with other types of run-time loadable components; they are officially
59 distributed, but not maintained by the project.
61 All the current overlays in OpenLDAP are listed and described in detail in the
70 This overlay can record accesses to a given backend database on another
73 This allows all of the activity on a given database to be reviewed using arbitrary
74 LDAP queries, instead of just logging to local flat text files. Configuration
75 options are available for selecting a subset of operation types to log, and to
76 automatically prune older log records from the logging database. Log records
77 are stored with audit schema to assure their readability whether viewed as LDIF
80 It is also used for {{SECT:delta-syncrepl replication}}
82 H3: Access Logging Configuration
84 The following is a basic example that implements Access Logging:
87 > suffix dc=example,dc=com
92 > logold (objectclass=person)
99 > by dn.base="cn=admin,dc=example,dc=com" read
101 The following is an example used for {{SECT:delta-syncrepl replication}}:
104 > suffix cn=accesslog
105 > directory /usr/local/var/openldap-accesslog
106 > rootdn cn=accesslog
108 > index entryCSN,objectClass,reqEnd,reqResult,reqStart
110 Accesslog overlay definitions for the primary db
113 > suffix dc=example,dc=com
119 > # scan the accesslog DB every day, and purge entries older than 7 days
120 > logpurge 07+00:00 01+00:00
122 An example search result against {{B:cn=accesslog}} might look like:
124 > [ghenry@suretec ghenry]# ldapsearch -x -b cn=accesslog
128 > # base <cn=accesslog> with scope subtree
129 > # filter: (objectclass=*)
135 > objectClass: auditContainer
138 > # 20080110163829.000004Z, accesslog
139 > dn: reqStart=20080110163829.000004Z,cn=accesslog
140 > objectClass: auditModify
141 > reqStart: 20080110163829.000004Z
142 > reqEnd: 20080110163829.000005Z
145 > reqAuthzID: cn=admin,dc=suretecsystems,dc=com
146 > reqDN: uid=suretec-46022f8$,ou=Users,dc=suretecsystems,dc=com
148 > reqMod: sambaPwdCanChange:- ###CENSORED###
149 > reqMod: sambaPwdCanChange:+ ###CENSORED###
150 > reqMod: sambaNTPassword:- ###CENSORED###
151 > reqMod: sambaNTPassword:+ ###CENSORED###
152 > reqMod: sambaPwdLastSet:- ###CENSORED###
153 > reqMod: sambaPwdLastSet:+ ###CENSORED###
154 > reqMod: entryCSN:= 20080110163829.095157Z#000000#000#000000
155 > reqMod: modifiersName:= cn=admin,dc=suretecsystems,dc=com
156 > reqMod: modifyTimestamp:= 20080110163829Z
166 H3: Further Information
168 {{slapo-accesslog(5)}} and the {{SECT:delta-syncrepl replication}} section.
173 The Audit Logging overlay can be used to record all changes on a given backend database to a specified log file.
177 If the need arises whereby changes need to be logged as standard LDIF, then the auditlog overlay {{B:slapo-auditlog (5)}}
178 can be used. Full examples are available in the man page {{B:slapo-auditlog (5)}}
180 H3: Audit Logging Configuration
182 If the directory is running vi {{F:slapd.d}}, then the following LDIF could be used to add the overlay to the overlay list
183 in {{B:cn=config}} and set what file the {{TERM:LDIF}} gets logged to (adjust to suit)
185 > dn: olcOverlay=auditlog,olcDatabase={1}hdb,cn=config
187 > objectClass: olcOverlayConfig
188 > objectClass: olcAuditLogConfig
189 > olcOverlay: auditlog
190 > olcAuditlogFile: /tmp/auditlog.ldif
193 In this example for testing, we are logging changes to {{F:/tmp/auditlog.ldif}}
195 A typical {{TERM:LDIF}} file created by {{B:slapo-auditlog(5)}} would look like:
197 > # add 1196797576 dc=suretecsystems,dc=com cn=admin,dc=suretecsystems,dc=com
198 > dn: dc=suretecsystems,dc=com
200 > objectClass: dcObject
201 > objectClass: organization
203 > o: Suretec Systems Ltd.
204 > structuralObjectClass: organization
205 > entryUUID: 1606f8f8-f06e-1029-8289-f0cc9d81e81a
206 > creatorsName: cn=admin,dc=suretecsystems,dc=com
207 > modifiersName: cn=admin,dc=suretecsystems,dc=com
208 > createTimestamp: 20051123130912Z
209 > modifyTimestamp: 20051123130912Z
210 > entryCSN: 20051123130912.000000Z#000001#000#000000
211 > auditContext: cn=accesslog
212 > # end add 1196797576
214 > # add 1196797577 dc=suretecsystems,dc=com cn=admin,dc=suretecsystems,dc=com
215 > dn: ou=Groups,dc=suretecsystems,dc=com
218 > objectClass: organizationalUnit
220 > structuralObjectClass: organizationalUnit
221 > entryUUID: 160aaa2a-f06e-1029-828a-f0cc9d81e81a
222 > creatorsName: cn=admin,dc=suretecsystems,dc=com
223 > modifiersName: cn=admin,dc=suretecsystems,dc=com
224 > createTimestamp: 20051123130912Z
225 > modifyTimestamp: 20051123130912Z
226 > entryCSN: 20051123130912.000000Z#000002#000#000000
227 > # end add 1196797577
230 H3: Further Information
232 {{:slapo-auditlog(5)}}
240 The chain overlay provides basic chaining capability to the underlying
243 What is chaining? It indicates the capability of a DSA to follow referrals on
244 behalf of the client, so that distributed systems are viewed as a single
245 virtual DSA by clients that are otherwise unable to "chase" (i.e. follow)
246 referrals by themselves.
248 The chain overlay is built on top of the ldap backend; it is compiled by
249 default when {{B:--enable-ldap}}.
252 H3: Chaining Configuration
254 In order to demonstrate how this overlay works, we shall discuss a typical
255 scenario which might be one master server and three Syncrepl slaves.
257 On each replica, add this near the top of the {{slapd.conf}}(5) file
258 (global), before any database definitions:
261 > chain-uri "ldap://ldapmaster.example.com"
262 > chain-idassert-bind bindmethod="simple"
263 > binddn="cn=Manager,dc=example,dc=com"
264 > credentials="<secret>"
267 > chain-return-error TRUE
269 Add this below your {{syncrepl}} statement:
271 > updateref "ldap://ldapmaster.example.com/"
273 The {{B:chain-tls}} statement enables TLS from the slave to the ldap master.
274 The DITs are exactly the same between these machines, therefore whatever user
275 bound to the slave will also exist on the master. If that DN does not have
276 update privileges on the master, nothing will happen.
278 You will need to restart the slave after these {{slapd.conf}} changes.
279 Then, if you are using {{loglevel stats}} (256), you can monitor an
280 {{ldapmodify}} on the slave and the master. (If you're using {{cn=config}}
281 no restart is required.)
283 Now start an {{ldapmodify}} on the slave and watch the logs. You should expect
286 > 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)
287 > Sep 6 09:27:25 slave1 slapd[29274]: conn=11 op=0 STARTTLS
288 > Sep 6 09:27:25 slave1 slapd[29274]: conn=11 op=0 RESULT oid= err=0 text=
289 > Sep 6 09:27:25 slave1 slapd[29274]: conn=11 fd=31 TLS established tls_ssf=256 ssf=256
290 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=1 BIND dn="uid=user1,ou=people,dc=example,dc=com" method=128
291 > 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
292 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=1 RESULT tag=97 err=0 text=
293 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=2 MOD dn="uid=user1,ou=People,dc=example,dc=com"
294 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=2 MOD attr=mail
295 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=2 RESULT tag=103 err=0 text=
296 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 op=3 UNBIND
297 > Sep 6 09:27:28 slave1 slapd[29274]: conn=11 fd=31 closed
298 > Sep 6 09:27:28 slave1 slapd[29274]: syncrepl_entry: LDAP_RES_SEARCH_ENTRY(LDAP_SYNC_MODIFY)
299 > Sep 6 09:27:28 slave1 slapd[29274]: syncrepl_entry: be_search (0)
300 > Sep 6 09:27:28 slave1 slapd[29274]: syncrepl_entry: uid=user1,ou=People,dc=example,dc=com
301 > Sep 6 09:27:28 slave1 slapd[29274]: syncrepl_entry: be_modify (0)
303 And on the master you will see this:
305 > Sep 6 09:23:57 ldapmaster slapd[2961]: conn=55902 op=3 PROXYAUTHZ dn="uid=user1,ou=people,dc=example,dc=com"
306 > Sep 6 09:23:57 ldapmaster slapd[2961]: conn=55902 op=3 MOD dn="uid=user1,ou=People,dc=example,dc=com"
307 > Sep 6 09:23:57 ldapmaster slapd[2961]: conn=55902 op=3 MOD attr=mail
308 > Sep 6 09:23:57 ldapmaster slapd[2961]: conn=55902 op=3 RESULT tag=103 err=0 text=
310 Note: You can clearly see the PROXYAUTHZ line on the master, indicating the
311 proper identity assertion for the update on the master. Also note the slave
312 immediately receiving the Syncrepl update from the master.
314 H3: Handling Chaining Errors
316 By default, if chaining fails, the original referral is returned to the client
317 under the assumption that the client might want to try and follow the referral.
319 With the following directive however, if the chaining fails at the provider
320 side, the actual error is returned to the client.
322 > chain-return-error TRUE
325 H3: Further Information
335 This overlay enforces a regular expression constraint on all values
336 of specified attributes during an LDAP modify request that contains add or modify
337 commands. It is used to enforce a more rigorous syntax when the underlying attribute
338 syntax is too general.
341 H3: Constraint Configuration
343 Configuration via {{slapd.conf}}(5) would look like:
346 > constraint_attribute mail regex ^[:alnum:]+@mydomain.com$
347 > constraint_attribute title uri
348 > ldap:///dc=catalog,dc=example,dc=com?title?sub?(objectClass=titleCatalog)
350 A specification like the above would reject any {{mail}} attribute which did not
351 look like {{<alpha-numeric string>@mydomain.com}}.
353 It would also reject any title attribute whose values were not listed in the
354 title attribute of any {{titleCatalog}} entries in the given scope.
356 An example for use with {{cn=config}}:
358 > dn: olcOverlay=constraint,olcDatabase={1}hdb,cn=config
360 > objectClass: olcOverlayConfig
361 > objectClass: olcConstraintConfig
362 > olcOverlay: constraint
363 > olcConstraintAttribute: mail regex ^[:alnum:]+@mydomain.com$
364 > olcConstraintAttribute: title uri ldap:///dc=catalog,dc=example,dc=com?title?sub?(objectClass=titleCatalog)
367 H3: Further Information
369 {{:slapo-constraint(5)}}
372 H2: Dynamic Directory Services
377 The {{dds}} overlay to {{slapd}}(8) implements dynamic objects as per {{REF:RFC2589}}.
378 The name {{dds}} stands for Dynamic Directory Services. It allows to define
379 dynamic objects, characterized by the {{dynamicObject}} objectClass.
381 Dynamic objects have a limited lifetime, determined by a time-to-live (TTL)
382 that can be refreshed by means of a specific refresh extended operation. This
383 operation allows to set the Client Refresh Period (CRP), namely the period
384 between refreshes that is required to preserve the dynamic object from expiration.
385 The expiration time is computed by adding the requested TTL to the current time.
386 When dynamic objects reach the end of their lifetime without being further
387 refreshed, they are automatically {{deleted}}. There is no guarantee of immediate
388 deletion, so clients should not count on it.
390 H3: Dynamic Directory Service Configuration
392 A usage of dynamic objects might be to implement dynamic meetings; in this case,
393 all the participants to the meeting are allowed to refresh the meeting object,
394 but only the creator can delete it (otherwise it will be deleted when the TTL expires).
396 If we add the overlay to an example database, specifying a Max TTL of 1 day, a
397 min of 10 seconds, with a default TTL of 1 hour. We'll also specify an interval
398 of 120 (less than 60s might be too small) seconds between expiration checks and a
399 tolerance of 5 second (lifetime of a dynamic object will be {{entryTtl + tolerance}}).
410 > entryExpireTimestamp
412 Creating a meeting is as simple as adding the following:
414 > dn: cn=OpenLDAP Documentation Meeting,ou=Meetings,dc=example,dc=com
415 > objectClass: groupOfNames
416 > objectClass: dynamicObject
417 > cn: OpenLDAP Documentation Meeting
418 > member: uid=ghenry,ou=People,dc=example,dc=com
419 > member: uid=hyc,ou=People,dc=example,dc=com
421 H4: Dynamic Directory Service ACLs
423 Allow users to start a meeting and to join it; restrict refresh to the {{member}};
424 restrict delete to the creator:
426 > access to attrs=userPassword
430 > access to dn.base="ou=Meetings,dc=example,dc=com"
434 > access to dn.onelevel="ou=Meetings,dc=example,dc=com"
436 > by dnattr=creatorsName write
439 > access to dn.onelevel="ou=Meetings,dc=example,dc=com"
441 > by dnattr=creatorsName write
445 > access to dn.onelevel="ou=Meetings,dc=example,dc=com"
447 > by dnattr=member manage
450 In simple terms, the user who created the {{OpenLDAP Documentation Meeting}} can add new attendees,
451 refresh the meeting using (basically complete control):
453 > ldapexop -x -H ldap://ldaphost "refresh" "cn=OpenLDAP Documentation Meeting,ou=Meetings,dc=example,dc=com" "120" -D "uid=ghenry,ou=People,dc=example,dc=com" -W
455 Any user can join the meeting, but not add another attendee, but they can refresh the meeting. The ACLs above are quite straight forward to understand.
458 H3: Further Information
468 This overlay extends the Compare operation to detect
469 members of a dynamic group. This overlay is now deprecated
470 as all of its functions are available using the
471 {{SECT:Dynamic Lists}} overlay.
474 H3: Dynamic Group Configuration
482 This overlay allows expansion of dynamic groups and lists. Instead of having the
483 group members or list attributes hard coded, this overlay allows us to define
484 an LDAP search whose results will make up the group or list.
486 H3: Dynamic List Configuration
488 This module can behave both as a dynamic list and dynamic group, depending on
489 the configuration. The syntax is as follows:
492 > dynlist-attrset <group-oc> <URL-ad> [member-ad]
494 The parameters to the {{F:dynlist-attrset}} directive have the following meaning:
495 * {{F:<group-oc>}}: specifies which object class triggers the subsequent LDAP search.
496 Whenever an entry with this object class is retrieved, the search is performed.
497 * {{F:<URL-ad>}}: is the name of the attribute which holds the search URI. It
498 has to be a subtype of {{F:labeledURI}}. The attributes and values present in
499 the search result are added to the entry unless {{F:member-ad}} is used (see
501 * {{F:member-ad}}: if present, changes the overlay behavior into a dynamic group.
502 Instead of inserting the results of the search in the entry, the distinguished name
503 of the results are added as values of this attribute.
505 Here is an example which will allow us to have an email alias which automatically
506 expands to all user's emails according to our LDAP filter:
508 In {{slapd.conf}}(5):
511 > dynlist-attrset nisMailAlias labeledURI
513 This means that whenever an entry which has the {{F:nisMailAlias}} object class is
514 retrieved, the search specified in the {{F:labeledURI}} attribute is performed.
516 Let's say we have this entry in our directory:
518 > cn=all,ou=aliases,dc=example,dc=com
520 > objectClass: nisMailAlias
521 > labeledURI: ldap:///ou=People,dc=example,dc=com?mail?one?(objectClass=inetOrgPerson)
523 If this entry is retrieved, the search specified in {{F:labeledURI}} will be
524 performed and the results will be added to the entry just as if they have always
525 been there. In this case, the search filter selects all entries directly
526 under {{F:ou=People}} that have the {{F:inetOrgPerson}} object class and retrieves
527 the {{F:mail}} attribute, if it exists.
529 This is what gets added to the entry when we have two users under {{F:ou=People}}
530 that match the filter:
531 !import "allmail-en.png"; align="center"; title="Dynamic list for email aliases"
532 FT[align="Center"] Figure X.Y: Dynamic List for all emails
534 The configuration for a dynamic group is similar. Let's see an example which would
535 automatically populate an {{F:allusers}} group with all the user accounts in the
538 In {{F:slapd.conf}}(5):
541 > dynlist-attrset groupOfNames labeledURI member
543 Let's apply it to the following entry:
545 > cn=allusers,ou=group,dc=example,dc=com
547 > objectClass: groupOfNames
548 > labeledURI: ldap:///ou=people,dc=example,dc=com??one?(objectClass=inetOrgPerson)
550 The behavior is similar to the dynamic list configuration we had before:
551 whenever an entry with the {{F:groupOfNames}} object class is retrieved, the
552 search specified in the {{F:labeledURI}} attribute is performed. But this time,
553 only the distinguished names of the results are added, and as values of the
554 {{F:member}} attribute.
557 !import "allusersgroup-en.png"; align="center"; title="Dynamic group for all users"
558 FT[align="Center"] Figure X.Y: Dynamic Group for all users
560 Note that a side effect of this scheme of dynamic groups is that the members
561 need to be specified as full DNs. So, if you are planning in using this for
562 {{F:posixGroup}}s, be sure to use RFC2307bis and some attribute which can hold
563 distinguished names. The {{F:memberUid}} attribute used in the {{F:posixGroup}}
564 object class can hold only names, not DNs, and is therefore not suitable for
568 H3: Further Information
570 {{:slapo-dynlist(5)}}
573 H2: Reverse Group Membership Maintenance
577 In some scenarios, it may be desirable for a client to be able to determine
578 which groups an entry is a member of, without performing an additional search.
579 Examples of this are applications using the {{TERM:DIT}} for access control
580 based on group authorization.
582 The {{B:memberof}} overlay updates an attribute (by default {{B:memberOf}}) whenever
583 changes occur to the membership attribute (by default {{B:member}}) of entries of the
584 objectclass (by default {{B:groupOfNames}}) configured to trigger updates.
586 Thus, it provides maintenance of the list of groups an entry is a member of,
587 when usual maintenance of groups is done by modifying the members on the group
590 H3: Member Of Configuration
592 The typical use of this overlay requires just enabling the overlay for a
593 specific database. For example, with the following minimal slapd.conf:
595 > include /usr/share/openldap/schema/core.schema
596 > include /usr/share/openldap/schema/cosine.schema
597 > modulepath /usr/lib/openldap
598 > moduleload memberof.la
599 > authz-regexp "gidNumber=0\\\+uidNumber=0,cn=peercred,cn=external,cn=auth"
600 > "cn=Manager,dc=example,dc=com"
602 > suffix "dc=example,dc=com"
603 > rootdn "cn=Manager,dc=example,dc=com"
605 > directory /var/lib/ldap2.4
607 > index objectClass eq
612 adding the following ldif:
615 > dn: dc=example,dc=com
616 > objectclass: domain
619 > dn: ou=Group,dc=example,dc=com
620 > objectclass: organizationalUnit
623 > dn: ou=People,dc=example,dc=com
624 > objectclass: organizationalUnit
627 > dn: uid=test1,ou=People,dc=example,dc=com
628 > objectclass: account
631 > dn: cn=testgroup,ou=Group,dc=example,dc=com
632 > objectclass: groupOfNames
634 > member: uid=test1,ou=People,dc=example,dc=com
636 Results in the following output from a search on the test1 user:
638 > # ldapsearch -LL -Y EXTERNAL -H ldapi:/// "(uid=test1)" -b dc=example,dc=com memberOf
639 > SASL/EXTERNAL authentication started
640 > SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
644 > dn: uid=test1,ou=People,dc=example,dc=com
645 > memberOf: cn=testgroup,ou=Group,dc=example,dc=com
647 Note that the {{B:memberOf}} attribute is an operational attribute, so it must be
648 requested explicitly.
651 H3: Further Information
653 {{:slapo-memberof(5)}}
656 H2: The Proxy Cache Engine
658 {{TERM:LDAP}} servers typically hold one or more subtrees of a
659 {{TERM:DIT}}. Replica (or shadow) servers hold shadow copies of
660 entries held by one or more master servers. Changes are propagated
661 from the master server to replica (slave) servers using LDAP Sync
662 replication. An LDAP cache is a special type of replica which holds
663 entries corresponding to search filters instead of subtrees.
667 The proxy cache extension of slapd is designed to improve the
668 responsiveness of the ldap and meta backends. It handles a search
670 by first determining whether it is contained in any cached search
671 filter. Contained requests are answered from the proxy cache's local
672 database. Other requests are passed on to the underlying ldap or
673 meta backend and processed as usual.
675 E.g. {{EX:(shoesize>=9)}} is contained in {{EX:(shoesize>=8)}} and
676 {{EX:(sn=Richardson)}} is contained in {{EX:(sn=Richards*)}}
678 Correct matching rules and syntaxes are used while comparing
679 assertions for query containment. To simplify the query containment
680 problem, a list of cacheable "templates" (defined below) is specified
681 at configuration time. A query is cached or answered only if it
682 belongs to one of these templates. The entries corresponding to
683 cached queries are stored in the proxy cache local database while
684 its associated meta information (filter, scope, base, attributes)
685 is stored in main memory.
687 A template is a prototype for generating LDAP search requests.
688 Templates are described by a prototype search filter and a list of
689 attributes which are required in queries generated from the template.
690 The representation for prototype filter is similar to {{REF:RFC4515}},
691 except that the assertion values are missing. Examples of prototype
692 filters are: (sn=),(&(sn=)(givenname=)) which are instantiated by
693 search filters (sn=Doe) and (&(sn=Doe)(givenname=John)) respectively.
695 The cache replacement policy removes the least recently used (LRU)
696 query and entries belonging to only that query. Queries are allowed
697 a maximum time to live (TTL) in the cache thus providing weak
698 consistency. A background task periodically checks the cache for
699 expired queries and removes them.
701 The Proxy Cache paper
702 ({{URL:http://www.openldap.org/pub/kapurva/proxycaching.pdf}}) provides
703 design and implementation details.
706 H3: Proxy Cache Configuration
708 The cache configuration specific directives described below must
709 appear after a {{EX:overlay proxycache}} directive within a
710 {{EX:"database meta"}} or {{EX:database ldap}} section of
711 the server's {{slapd.conf}}(5) file.
713 H4: Setting cache parameters
715 > proxyCache <DB> <maxentries> <nattrsets> <entrylimit> <period>
717 This directive enables proxy caching and sets general cache
718 parameters. The <DB> parameter specifies which underlying database
719 is to be used to hold cached entries. It should be set to
720 {{EX:bdb}} or {{EX:hdb}}. The <maxentries> parameter specifies the
721 total number of entries which may be held in the cache. The
722 <nattrsets> parameter specifies the total number of attribute sets
723 (as specified by the {{EX:proxyAttrSet}} directive) that may be
724 defined. The <entrylimit> parameter specifies the maximum number of
725 entries in a cacheable query. The <period> specifies the consistency
726 check period (in seconds). In each period, queries with expired
729 H4: Defining attribute sets
731 > proxyAttrset <index> <attrs...>
733 Used to associate a set of attributes to an index. Each attribute
734 set is associated with an index number from 0 to <numattrsets>-1.
735 These indices are used by the proxyTemplate directive to define
738 H4: Specifying cacheable templates
740 > proxyTemplate <prototype_string> <attrset_index> <TTL>
742 Specifies a cacheable template and the "time to live" (in sec) <TTL>
743 for queries belonging to the template. A template is described by
744 its prototype filter string and set of required attributes identified
750 An example {{slapd.conf}}(5) database section for a caching server
751 which proxies for the {{EX:"dc=example,dc=com"}} subtree held
752 at server {{EX:ldap.example.com}}.
755 > suffix "dc=example,dc=com"
756 > rootdn "dc=example,dc=com"
757 > uri ldap://ldap.example.com/
759 > proxycache bdb 100000 1 1000 100
760 > proxyAttrset 0 mail postaladdress telephonenumber
761 > proxyTemplate (sn=) 0 3600
762 > proxyTemplate (&(sn=)(givenName=)) 0 3600
763 > proxyTemplate (&(departmentNumber=)(secretary=*)) 0 3600
766 > directory ./testrun/db.2.a
767 > index objectClass eq
768 > index cn,sn,uid,mail pres,eq,sub
771 H5: Cacheable Queries
773 A LDAP search query is cacheable when its filter matches one of the
774 templates as defined in the "proxyTemplate" statements and when it references
775 only the attributes specified in the corresponding attribute set.
776 In the example above the attribute set number 0 defines that only the
777 attributes: {{EX:mail postaladdress telephonenumber}} are cached for the following
782 > Filter: (&(sn=Richard*)(givenName=jack))
783 > Attrs: mail telephoneNumber
785 is cacheable, because it matches the template {{EX:(&(sn=)(givenName=))}} and its
786 attributes are contained in proxyAttrset 0.
788 > Filter: (&(sn=Richard*)(telephoneNumber))
791 is not cacheable, because the filter does not match the template,
792 nor is the attribute givenName stored in the cache
794 > Filter: (|(sn=Richard*)(givenName=jack))
795 > Attrs: mail telephoneNumber
797 is not cacheable, because the filter does not match the template ( logical
798 OR "|" condition instead of logical AND "&" )
801 H3: Further Information
806 H2: Password Policies
811 This overlay follows the specifications contained in the draft RFC titled
812 draft-behera-ldap-password-policy-09. While the draft itself is expired, it has
813 been implemented in several directory servers, including slapd. Nonetheless,
814 it is important to note that it is a draft, meaning that it is subject to change
815 and is a work-in-progress.
817 The key abilities of the password policy overlay are as follows:
819 * Enforce a minimum length for new passwords
820 * Make sure passwords are not changed too frequently
821 * Cause passwords to expire, provide warnings before they need to be changed, and allow a fixed number of 'grace' logins to allow them to be changed after they have expired
822 * Maintain a history of passwords to prevent password re-use
823 * Prevent password guessing by locking a password for a specified period of time after repeated authentication failures
824 * Force a password to be changed at the next authentication
825 * Set an administrative lock on an account
826 * Support multiple password policies on a default or a per-object basis.
827 * Perform arbitrary quality checks using an external loadable module. This is a non-standard extension of the draft RFC.
830 H3: Password Policy Configuration
832 Instantiate the module in the database where it will be used, after adding the
833 new ppolicy schema and loading the ppolicy module. The following example shows
834 the ppolicy module being added to the database that handles the naming
835 context "dc=example,dc=com". In this example we are also specifying the DN of
836 a policy object to use if none other is specified in a user's object.
839 > suffix "dc=example,dc=com"
840 > [...additional database configuration directives go here...]
843 > ppolicy_default "cn=default,ou=policies,dc=example,dc=com"
846 Now we need a container for the policy objects. In our example the password
847 policy objects are going to be placed in a section of the tree called
848 "ou=policies,dc=example,dc=com":
850 > dn: ou=policies,dc=example,dc=com
851 > objectClass: organizationalUnit
856 The default policy object that we are creating defines the following policies:
858 * The user is allowed to change his own password. Note that the directory ACLs for this attribute can also affect this ability (pwdAllowUserChange: TRUE).
859 * The name of the password attribute is "userPassword" (pwdAttribute: userPassword). Note that this is the only value that is accepted by OpenLDAP for this attribute.
860 * The server will check the syntax of the password. If the server is unable to check the syntax (i.e., it was hashed or otherwise encoded by the client) it will return an error refusing the password (pwdCheckQuality: 2).
861 * When a client includes the Password Policy Request control with a bind request, the server will respond with a password expiration warning if it is going to expire in ten minutes or less (pwdExpireWarning: 600). The warnings themselves are returned in a Password Policy Response control.
862 * When the password for a DN has expired, the server will allow five additional "grace" logins (pwdGraceAuthNLimit: 5).
863 * The server will maintain a history of the last five passwords that were used for a DN (pwdInHistory: 5).
864 * The server will lock the account after the maximum number of failed bind attempts has been exceeded (pwdLockout: TRUE).
865 * When the server has locked an account, the server will keep it locked until an administrator unlocks it (pwdLockoutDuration: 0)
866 * The server will reset its failed bind count after a period of 30 seconds.
867 * Passwords will not expire (pwdMaxAge: 0).
868 * Passwords can be changed as often as desired (pwdMinAge: 0).
869 * Passwords must be at least 5 characters in length (pwdMinLength: 5).
870 * The password does not need to be changed at the first bind or when the administrator has reset the password (pwdMustChange: FALSE)
871 * The current password does not need to be included with password change requests (pwdSafeModify: FALSE)
872 * The server will only allow five failed binds in a row for a particular DN (pwdMaxFailure: 5).
875 The actual policy would be:
877 > dn: cn=default,ou=policies,dc=example,dc=com
879 > objectClass: pwdPolicy
880 > objectClass: person
882 > pwdAllowUserChange: TRUE
883 > pwdAttribute: userPassword
885 > pwdExpireWarning: 600
886 > pwdFailureCountInterval: 30
887 > pwdGraceAuthNLimit: 5
890 > pwdLockoutDuration: 0
895 > pwdMustChange: FALSE
896 > pwdSafeModify: FALSE
899 You can create additional policy objects as needed.
902 There are two ways password policy can be applied to individual objects:
904 1. The pwdPolicySubentry in a user's object - If a user's object has a
905 pwdPolicySubEntry attribute specifying the DN of a policy object, then
906 the policy defined by that object is applied.
908 2. Default password policy - If there is no specific pwdPolicySubentry set
909 for an object, and the password policy module was configured with the DN of a
910 default policy object and if that object exists, then the policy defined in
911 that object is applied.
913 Please see {{slapo-ppolicy(5)}} for complete explanations of features and discussion of
914 "Password Management Issues" at {{URL:http://www.connexitor.com/forums/viewtopic.php?f=6&t=25}}
917 H3: Further Information
919 {{:slapo-ppolicy(5)}}
922 H2: Referential Integrity
927 This overlay can be used with a backend database such as slapd-bdb(5)
928 to maintain the cohesiveness of a schema which utilizes reference
931 Whenever a {{modrdn}} or {{delete}} is performed, that is, when an entry's DN
932 is renamed or an entry is removed, the server will search the directory for
933 references to this DN (in selected attributes: see below) and update them
934 accordingly. If it was a {{delete}} operation, the reference is deleted. If it
935 was a {{modrdn}} operation, then the reference is updated with the new DN.
937 For example, a very common administration task is to maintain group membership
938 lists, specially when users are removed from the directory. When an
939 user account is deleted or renamed, all groups this user is a member of have to be
940 updated. LDAP administrators usually have scripts for that. But we can use the
941 {{F:refint}} overlay to automate this task. In this example, if the user is
942 removed from the directory, the overlay will take care to remove the user from
943 all the groups he/she was a member of. No more scripting for this.
945 H3: Referential Integrity Configuration
947 The configuration for this overlay is as follows:
950 > refint_attributes <attribute [attribute ...]>
951 > refint_nothing <string>
953 * {{F:refint_attributes}}: this parameter specifies a space separated list of
954 attributes which will have the referential integrity maintained. When an entry is
955 removed or has its DN renamed, the server will do an internal search for any of the
956 {{F:refint_attributes}} that point to the affected DN and update them accordingly. IMPORTANT:
957 the attributes listed here must have the {{F:distinguishedName}} syntax, that is,
959 * {{F:refint_nothing}}: some times, while trying to maintain the referential
960 integrity, the server has to remove the last attribute of its kind from an
961 entry. This may be prohibited by the schema: for example, the
962 {{F:groupOfNames}} object class requires at least one member. In these cases,
963 the server will add the attribute value specified in {{F:refint_nothing}}
966 To illustrate this overlay, we will use the group membership scenario.
971 > refint_attributes member
972 > refint_nothing "cn=admin,dc=example,dc=com"
974 This configuration tells the overlay to maintain the referential integrity of the {{F:member}}
975 attribute. This attribute is used in the {{F:groupOfNames}} object class which always needs
976 a member, so we add the {{F:refint_nothing}} directive to fill in the group with a standard
977 member should all the members vanish.
979 If we have the following group membership, the refint overlay will
980 automatically remove {{F:john}} from the group if his entry is removed from the
983 !import "refint.png"; align="center"; title="Group membership"
984 FT[align="Center"] Figure X.Y: Maintaining referential integrity in groups
986 Notice that if we rename ({{F:modrdn}}) the {{F:john}} entry to, say, {{F:jsmith}}, the refint
987 overlay will also rename the reference in the {{F:member}} attribute, so the group membership
990 If we removed all users from the directory who are a member of this group, then the end result
991 would be a single member in the group: {{F:cn=admin,dc=example,dc=com}}. This is the
992 {{F:refint_nothing}} parameter kicking into action so that the schema is not violated.
995 H3: Further Information
1005 This overlay is useful to test the behavior of clients when
1006 server-generated erroneous and/or unusual responses occur,
1007 for example; error codes, referrals, excessive response times and so on.
1009 This would be classed as a debugging tool whilst developing client software
1010 or additional Overlays.
1012 For detailed information, please see the {{slapo-retcode(5)}} man page.
1015 H3: Return Code Configuration
1017 The retcode overlay utilizes the "return code" schema described in the man page.
1018 This schema is specifically designed for use with this overlay and is not intended
1019 to be used otherwise.
1021 Note: The necessary schema is loaded automatically by the overlay.
1023 An example configuration might be:
1026 > retcode-parent "ou=RetCodes,dc=example,dc=com"
1027 > include ./retcode.conf
1029 > retcode-item "cn=Unsolicited" 0x00 unsolicited="0"
1030 > retcode-item "cn=Notice of Disconnect" 0x00 unsolicited="1.3.6.1.4.1.1466.20036"
1031 > retcode-item "cn=Pre-disconnect" 0x34 flags="pre-disconnect"
1032 > retcode-item "cn=Post-disconnect" 0x34 flags="post-disconnect"
1034 Note: {{retcode.conf}} can be found in the openldap source at: {{F:tests/data/retcode.conf}}
1036 An excerpt of a {{F:retcode.conf}} would be something like:
1038 > retcode-item "cn=success" 0x00
1040 > retcode-item "cn=success w/ delay" 0x00 sleeptime=2
1042 > retcode-item "cn=operationsError" 0x01
1043 > retcode-item "cn=protocolError" 0x02
1044 > retcode-item "cn=timeLimitExceeded" 0x03 op=search
1045 > retcode-item "cn=sizeLimitExceeded" 0x04 op=search
1046 > retcode-item "cn=compareFalse" 0x05 op=compare
1047 > retcode-item "cn=compareTrue" 0x06 op=compare
1048 > retcode-item "cn=authMethodNotSupported" 0x07
1049 > retcode-item "cn=strongAuthNotSupported" 0x07 text="same as authMethodNotSupported"
1050 > retcode-item "cn=strongAuthRequired" 0x08
1051 > retcode-item "cn=strongerAuthRequired" 0x08 text="same as strongAuthRequired"
1053 Please see {{F:tests/data/retcode.conf}} for a complete {{F:retcode.conf}}
1056 H3: Further Information
1058 {{:slapo-retcode(5)}}
1066 It performs basic DN/data rewrite and objectClass/attributeType mapping. Its
1067 usage is mostly intended to provide virtual views of existing data either
1068 remotely, in conjunction with the proxy backend described in {{slapd-ldap(5)}},
1069 or locally, in conjunction with the relay backend described in {{slapd-relay(5)}}.
1071 This overlay is extremely configurable and advanced, therefore recommended
1072 reading is the {{slapo-rwm(5)}} man page.
1075 H3: Rewrite/Remap Configuration
1078 H3: Further Information
1088 This overlay implements the provider-side support for syncrepl
1089 replication, including persistent search functionality
1092 H3: Sync Provider Configuration
1095 H3: Further Information
1097 {{:slapo-syncprov(5)}}
1100 H2: Translucent Proxy
1105 This overlay can be used with a backend database such as slapd-bdb (5)
1106 to create a "translucent proxy".
1108 Content of entries retrieved from a remote LDAP server can be partially
1109 overridden by the database.
1112 H3: Translucent Proxy Configuration
1116 H3: Further Information
1118 {{:slapo-translucent(5)}}
1121 H2: Attribute Uniqueness
1126 This overlay can be used with a backend database such as slapd-bdb (5)
1127 to enforce the uniqueness of some or all attributes within a subtree.
1130 H3: Attribute Uniqueness Configuration
1133 H3: Further Information
1135 {{:slapo-unique(5)}}
1143 The Value Sorting overlay can be used with a backend database to sort the
1144 values of specific multi-valued attributes within a subtree. The sorting occurs
1145 whenever the attributes are returned in a search response.
1147 H3: Value Sorting Configuration
1149 Sorting can be specified in ascending or descending order, using either numeric
1150 or alphanumeric sort methods. Additionally, a "weighted" sort can be specified,
1151 which uses a numeric weight prepended to the attribute values.
1153 The weighted sort is always performed in ascending order, but may be combined
1154 with the other methods for values that all have equal weights. The weight is
1155 specified by prepending an integer weight {<weight>} in front of each value
1156 of the attribute for which weighted sorting is desired. This weighting factor
1157 is stripped off and never returned in search results.
1159 Here are a few examples:
1161 > loglevel sync stats
1164 > suffix "dc=suretecsystems,dc=com"
1165 > directory /usr/local/var/openldap-data
1170 > valsort-attr memberUid ou=Groups,dc=suretecsystems,dc=com alpha-ascend
1172 For example, ascend:
1174 > # sharedemail, Groups, suretecsystems.com
1175 > dn: cn=sharedemail,ou=Groups,dc=suretecsystems,dc=com
1176 > objectClass: posixGroup
1181 > memberUid: dovecot
1183 > memberUid: suretec
1185 For weighted, we change our data to:
1187 > # sharedemail, Groups, suretecsystems.com
1188 > dn: cn=sharedemail,ou=Groups,dc=suretecsystems,dc=com
1189 > objectClass: posixGroup
1193 > memberUid: {4}admin
1194 > memberUid: {2}dovecot
1195 > memberUid: {1}laura
1196 > memberUid: {3}suretec
1198 and change the config to:
1201 > valsort-attr memberUid ou=Groups,dc=suretecsystems,dc=com weighted
1203 Searching now results in:
1205 > # sharedemail, Groups, OxObjects, suretecsystems.com
1206 > dn: cn=sharedemail,ou=Groups,ou=OxObjects,dc=suretecsystems,dc=com
1207 > objectClass: posixGroup
1212 > memberUid: dovecot
1213 > memberUid: suretec
1217 H3: Further Information
1219 {{:slapo-valsort(5)}}
1222 H2: Overlay Stacking
1227 Overlays can be stacked, which means that more than one overlay
1228 can be instantiated for each database, or for the {{EX:frontend}}.
1229 As a consequence, each overlays function is called, if defined,
1230 when overlay execution is invoked.
1231 Multiple overlays are executed in reverse order (as a stack)
1232 with respect to their definition in slapd.conf (5), or with respect
1233 to their ordering in the config database, as documented in slapd-config (5).
1236 H3: Example Scenarios