1 .TH SLAPD-LDAP 5 "RELEASEDATE" "OpenLDAP LDVERSION"
2 .\" Copyright 1998-2010 The OpenLDAP Foundation All Rights Reserved.
3 .\" Copying restrictions apply. See COPYRIGHT/LICENSE.
6 slapd\-ldap \- LDAP backend to slapd
12 is not an actual database; instead it acts as a proxy to forward incoming
13 requests to another LDAP server. While processing requests it will also
14 chase referrals, so that referrals are fully processed instead of being
15 returned to the slapd client.
17 Sessions that explicitly Bind to the back-ldap database always create their
18 own private connection to the remote LDAP server. Anonymous sessions will
19 share a single anonymous connection to the remote server. For sessions bound
20 through other mechanisms, all sessions with the same DN will share the
21 same connection. This connection pooling strategy can enhance the proxy's
22 efficiency by reducing the overhead of repeatedly making/breaking multiple
25 The ldap database can also act as an information service, i.e. the identity
26 of locally authenticated clients is asserted to the remote server, possibly
27 in some modified form.
28 For this purpose, the proxy binds to the remote server with some
29 administrative identity, and, if required, authorizes the asserted identity.
33 The administrative identity of the proxy, on the remote server, must be
34 allowed to authorize by means of appropriate
42 must contain schema information for the attributes and objectClasses
43 used in filters, request DN and request-related data in general.
44 It should also contain schema information for the data returned
45 by the proxied server.
46 It is the responsibility of the proxy administrator to keep the schema
47 of the proxy lined up with that of the proxied server.
50 Note: When looping back to the same instance of
52 each connection requires a new thread; as a consequence,
54 must be compiled with thread support, and the \fBthreads\fP parameter
55 may need some tuning; in those cases, one may consider using
57 instead, which performs the relayed operation
58 internally and thus reuses the same connection.
63 options apply to the LDAP backend database.
64 That is, they must follow a "database ldap" line and come before any
65 subsequent "backend" or "database" lines.
66 Other database options are described in the
71 Note: In early versions of back-ldap it was recommended to always set
84 This was required because operational attributes related to entry creation
85 and modification should not be proxied, as they could be mistakenly written
86 to the target server(s), generating an error.
87 The current implementation automatically sets lastmod to \fBoff\fP,
88 so its use is redundant and should be omitted.
92 LDAP server to use. Multiple URIs can be set in a single
94 argument, resulting in the underlying library automatically
95 call the first server of the list that responds, e.g.
97 \fBuri "ldap://host/ ldap://backup\-host/"\fP
99 The URI list is space- or comma-separated.
100 Whenever the server that responds is not the first one in the list,
101 the list is rearranged and the responsive server is moved to the head,
102 so that it will be first contacted the next time a connection
107 .B bindmethod=simple|sasl [binddn=<simple DN>] [credentials=<simple password>]
108 .B [saslmech=<SASL mech>] [secprops=<properties>] [realm=<realm>]
109 .B [authcId=<authentication ID>] [authzId=<authorization ID>]
110 .B [starttls=no|yes|critical]
113 .B [tls_cacert=<file>]
114 .B [tls_cacertdir=<path>]
115 .B [tls_reqcert=never|allow|try|demand]
116 .B [tls_ciphersuite=<ciphers>]
117 .B [tls_protocol_min=<version>]
118 .B [tls_crlcheck=none|peer|all]
120 Allows to define the parameters of the authentication method that is
121 internally used by the proxy to collect info related to access control,
122 and whenever an operation occurs with the identity of the rootdn
123 of the LDAP proxy database.
124 The identity defined by this directive, according to the properties
125 associated to the authentication method, is supposed to have read access
126 on the target server to attributes used on the proxy for ACL checking.
128 There is no risk of giving away such values; they are only used to
130 The default is to use
132 bind, with empty \fIbinddn\fP and \fIcredentials\fP,
133 which means that the related operations will be performed anonymously.
134 If not set, and if \fBidassert\-bind\fP is defined, this latter identity
135 is used instead. See \fBidassert\-bind\fP for details.
137 The connection between the proxy database and the remote server
138 associated to this identity is cached regardless of the lifespan
139 of the client-proxy connection that first established it.
141 .B This identity is by no means implicitly used by the proxy
142 .B when the client connects anonymously.
145 feature, instead, in some cases can be crafted to implement that behavior,
146 which is \fIintrinsically unsafe and should be used with extreme care\fP.
147 This directive obsoletes
152 The TLS settings default to the same as the main slapd TLS settings,
155 which defaults to "demand".
159 .B cancel {ABANDON|ignore|exop[\-discover]}
160 Defines how to handle operation cancellation.
163 is invoked, so the operation is abandoned immediately.
166 no action is taken and any further response is ignored; this may result
167 in further response messages to be queued for that connection, so it is
168 recommended that long lasting connections are timed out either by
172 so that resources eventually get released.
177 operation (RFC 3909) is issued, resulting in the cancellation
178 of the current operation; the
180 operation waits for remote server response, so its use
181 may not be recommended.
186 extended operation is detected by reading the remote server's root DSE.
189 .B chase\-referrals {YES|no}
190 enable/disable automatic referral chasing, which is delegated to the
191 underlying libldap, with rebinding eventually performed if the
192 \fBrebind\-as\-user\fP directive is used. The default is to chase referrals.
196 This directive causes a cached connection to be dropped an recreated
197 after a given ttl, regardless of being idle or not.
200 .B idassert\-authzFrom <authz-regexp>
201 if defined, selects what
203 identities are authorized to exploit the identity assertion feature.
206 follows the rules defined for the
213 for details on the syntax of this field.
218 .B bindmethod=none|simple|sasl [binddn=<simple DN>] [credentials=<simple password>]
219 .B [saslmech=<SASL mech>] [secprops=<properties>] [realm=<realm>]
220 .B [authcId=<authentication ID>] [authzId=<authorization ID>]
221 .B [authz={native|proxyauthz}] [mode=<mode>] [flags=<flags>]
222 .B [starttls=no|yes|critical]
225 .B [tls_cacert=<file>]
226 .B [tls_cacertdir=<path>]
227 .B [tls_reqcert=never|allow|try|demand]
228 .B [tls_ciphersuite=<ciphers>]
229 .B [tls_protocol_min=<version>]
230 .B [tls_crlcheck=none|peer|all]
232 Allows to define the parameters of the authentication method that is
233 internally used by the proxy to authorize connections that are
234 authenticated by other databases.
235 The identity defined by this directive, according to the properties
236 associated to the authentication method, is supposed to have auth access
237 on the target server to attributes used on the proxy for authentication
238 and authorization, and to be allowed to authorize the users.
239 This requires to have
241 privileges on a wide set of DNs, e.g.
242 .BR authzTo=dn.subtree:"" ,
243 and the remote server to have
251 for details on these statements and for remarks and drawbacks about
253 The supported bindmethods are
255 \fBnone|simple|sasl\fP
259 is the default, i.e. no \fIidentity assertion\fP is performed.
261 The authz parameter is used to instruct the SASL bind to exploit
263 SASL authorization, if available; since connections are cached,
264 this should only be used when authorizing with a fixed identity
265 (e.g. by means of the
270 Otherwise, the default
272 is used, i.e. the proxyAuthz control (Proxied Authorization, RFC 4370)
273 is added to all operations.
275 The supported modes are:
277 \fB<mode> := {legacy|anonymous|none|self}\fP
283 is given, the proxy always authorizes that identity.
284 .B <authorization ID>
291 The former is supposed to be expanded by the remote server according
292 to the authz rules; see
295 In the latter case, whether or not the
297 prefix is present, the string must pass DN validation and normalization.
301 which implies that the proxy will either perform a simple bind as the
303 or a SASL bind as the
305 and assert the client's identity when it is not anonymous.
306 Direct binds are always proxied.
307 The other modes imply that the proxy will always either perform a simple bind
310 or a SASL bind as the
313 .BR idassert\-authzFrom
314 rules (see below), in which case the operation will fail;
315 eventually, it will assert some other identity according to
317 Other identity assertion modes are
321 which respectively mean that the
328 which means that no proxyAuthz control will be used, so the
332 identity will be asserted.
333 For all modes that require the use of the
335 control, on the remote server the proxy identity must have appropriate
337 permissions, or the asserted identities must have appropriate
339 permissions. Note, however, that the ID assertion feature is mostly
340 useful when the asserted identities do not exist on the remote server.
344 \fBoverride,[non\-]prescriptive,proxy\-authz\-[non\-]critical\fP
348 flag is used, identity assertion takes place even when the database
349 is authorizing for the identity of the client, i.e. after binding
350 with the provided identity, and thus authenticating it, the proxy
351 performs the identity assertion using the configured identity and
352 authentication method.
356 flag is used (the default), operations fail with
357 \fIinappropriateAuthentication\fP
358 for those identities whose assertion is not allowed by the
359 .B idassert\-authzFrom
363 flag is used, operations are performed anonymously for those identities
364 whose assertion is not allowed by the
365 .B idassert\-authzFrom
369 .B proxy\-authz\-non\-critical
370 flag is used (the default), the proxyAuthz control is not marked as critical,
371 in violation of RFC 4370. Use of
372 .B proxy\-authz\-critical
375 The TLS settings default to the same as the main slapd TLS settings,
378 which defaults to "demand".
380 The identity associated to this directive is also used for privileged
381 operations whenever \fBidassert\-bind\fP is defined and \fBacl\-bind\fP
382 is not. See \fBacl\-bind\fP for details.
384 This directive obsoletes
385 .BR idassert\-authcDN ,
386 .BR idassert\-passwd ,
389 .BR idassert\-method .
393 .B idassert-passthru <authz-regexp>
394 if defined, selects what
396 identities bypass the identity assertion feature.
397 Those identities need to be known by the remote host.
400 follows the rules defined for the
407 for details on the syntax of this field.
411 .B idle\-timeout <time>
412 This directive causes a cached connection to be dropped an recreated
413 after it has been idle for the specified time.
416 .B network\-timeout <time>
417 Sets the network timeout value after which
418 .BR poll (2)/ select (2)
421 returns in case of no activity.
422 The value is in seconds, and it can be specified as for
429 do not return search reference responses.
430 By default, they are returned unless request is LDAPv2.
433 .B noundeffilter <NO|yes>
436 return success instead of searching if a filter is undefined or contains
438 By default, the search is propagated after replacing undefined portions
440 .BR (!(objectClass=*)) ,
441 which corresponds to the empty result set.
444 .B protocol\-version {0,2,3}
445 This directive indicates what protocol version must be used to contact
447 If set to 0 (the default), the proxy uses the same protocol version
448 used by the client, otherwise the requested protocol is used.
449 The proxy returns \fIunwillingToPerform\fP if an operation that is
450 incompatible with the requested protocol is attempted.
453 .B proxy\-whoami {NO|yes}
454 Turns on proxying of the WhoAmI extended operation. If this option is
455 given, back-ldap will replace slapd's original WhoAmI routine with its
456 own. On slapd sessions that were authenticated by back-ldap, the WhoAmI
457 request will be forwarded to the remote LDAP server. Other sessions will
458 be handled by the local slapd, as before. This option is mainly useful
459 in conjunction with Proxy Authorization.
462 .B quarantine <interval>,<num>[;<interval>,<num>[...]]
463 Turns on quarantine of URIs that returned
464 .IR LDAP_UNAVAILABLE ,
465 so that an attempt to reconnect only occurs at given intervals instead
466 of any time a client requests an operation.
467 The pattern is: retry only after at least
469 seconds elapsed since last attempt, for exactly
471 times; then use the next pattern.
474 for the last pattern is "\fB+\fP", it retries forever; otherwise,
475 no more retries occur.
476 The process can be restarted by resetting the \fIolcDbQuarantine\fP
477 attribute of the database entry in the configuration backend.
480 .B rebind\-as\-user {NO|yes}
481 If this option is given, the client's bind credentials are remembered
482 for rebinds, when trying to re-establish a broken connection,
483 or when chasing a referral, if
489 .B session\-tracking\-request {NO|yes}
490 Adds session tracking control for all requests.
491 The client's IP and hostname, and the identity associated to each request,
492 if known, are sent to the remote server for informational purposes.
493 This directive is incompatible with setting \fIprotocol\-version\fP to 2.
496 .B single\-conn {NO|yes}
497 Discards current cached connection when the client rebinds.
500 .B t\-f\-support {NO|yes|discover}
501 enable if the remote server supports absolute filters
502 (see \fIdraft-zeilenga-ldap-t-f\fP for details).
505 support is detected by reading the remote server's root DSE.
508 .B timeout [<op>=]<val> [...]
509 This directive allows to set per-operation timeouts.
512 \fB<op> ::= bind, add, delete, modrdn, modify, compare, search\fP
514 The overall duration of the \fBsearch\fP operation is controlled either
515 by the \fBtimelimit\fP parameter or by server-side enforced
516 time limits (see \fBtimelimit\fP and \fBlimits\fP in
519 This \fBtimeout\fP parameter controls how long the target can be
520 irresponsive before the operation is aborted.
521 Timeout is meaningless for the remaining operations,
522 \fBunbind\fP and \fBabandon\fP, which do not imply any response,
523 while it is not yet implemented in currently supported \fBextended\fP
525 If no operation is specified, the timeout \fBval\fP affects all
526 supported operations.
528 Note: if the timelimit is exceeded, the operation is cancelled
529 (according to the \fBcancel\fP directive);
530 the protocol does not provide any means to rollback operations,
531 so the client will not be notified about the result of the operation,
532 which may eventually succeeded or not.
533 In case the timeout is exceeded during a bind operation, the connection
534 is destroyed, according to RFC4511.
536 Note: in some cases, this backend may issue binds prior
537 to other operations (e.g. to bind anonymously or with some prescribed
538 identity according to the \fBidassert\-bind\fP directive).
539 In this case, the timeout of the operation that resulted in the bind
544 .B tls {[try\-]start|[try\-]propagate|ldaps}
547 .B [tls_cacert=<file>]
548 .B [tls_cacertdir=<path>]
549 .B [tls_reqcert=never|allow|try|demand]
550 .B [tls_ciphersuite=<ciphers>]
551 .B [tls_crlcheck=none|peer|all]
553 Specify the use of TLS when a regular connection is initialized. The
554 StartTLS extended operation will be used unless the URI directive protocol
555 scheme is \fBldaps://\fP. In that case this keyword may only be
556 set to "ldaps" and the StartTLS operation will not be used.
557 \fBpropagate\fP issues the StartTLS operation only if the original
559 The \fBtry\-\fP prefix instructs the proxy to continue operations
560 if the StartTLS operation failed; its use is \fBnot\fP recommended.
562 The TLS settings default to the same as the main slapd TLS settings,
565 which defaults to "demand".
569 .B use\-temporary\-conn {NO|yes}
572 create a temporary connection whenever competing with other threads
573 for a shared one; otherwise, wait until the shared connection is available.
575 .SH BACKWARD COMPATIBILITY
576 The LDAP backend has been heavily reworked between releases 2.2 and 2.3,
577 and subsequently between 2.3 and 2.4.
578 As a side-effect, some of the traditional directives have been
579 deprecated and should be no longer used, as they might disappear
583 .B acl\-authcDN "<administrative DN for access control purposes>"
584 Formerly known as the
586 it is the DN that is used to query the target server for acl checking;
587 it is supposed to have read access on the target server to attributes used
588 on the proxy for acl checking.
589 There is no risk of giving away such values; they are only used to
592 .B The acl\-authcDN identity is by no means implicitly used by the proxy
593 .B when the client connects anonymously.
596 feature can be used (at own risk) for that purpose instead.
598 This directive is obsoleted by the
602 when \fIbindmethod\fP=\fBsimple\fP, and will be dismissed in the future.
605 .B acl\-passwd <password>
606 Formerly known as the
608 it is the password used with the above
611 This directive is obsoleted by the
615 when \fIbindmethod\fP=\fBsimple\fP, and will be dismissed in the future.
618 .B idassert\-authcDN "<administrative DN for proxyAuthz purposes>"
619 DN which is used to propagate the client's identity to the target
620 by means of the proxyAuthz control when the client does not
621 belong to the DIT fragment that is being proxied by back-ldap.
622 This directive is obsoleted by the
626 when \fIbindmethod\fP=\fBsimple\fP, and will be dismissed in the future.
629 .B idassert\-passwd <password>
630 Password used with the
633 This directive is obsoleted by the
637 when \fIbindmethod\fP=\fBsimple\fP, and will be dismissed in the future.
640 .B idassert\-mode <mode> [<flags>]
642 .I identity assertion
644 This directive is obsoleted by the
648 and will be dismissed in the future.
651 .B idassert\-method <method> [<saslargs>]
652 This directive is obsoleted by the
656 and will be dismissed in the future.
660 this directive is no longer supported. Use the
662 directive as described above.
665 .B server <hostname[:port]>
666 this directive is no longer supported. Use the
668 directive as described above.
671 .B suffixmassage, map, rewrite*
672 These directives are no longer supported by back-ldap; their
673 functionality is now delegated to the
675 overlay. Essentially, add a statement
679 first, and prefix all rewrite/map statements with
681 to obtain the original behavior.
685 .\" However, to ease update from existing configurations, back-ldap still
686 .\" recognizes them and automatically instantiates the
688 .\" overlay if available and not instantiated yet.
689 .\" This behavior may change in the future.
694 backend does not honor all ACL semantics as described in
695 .BR slapd.access (5).
696 In general, access checking is delegated to the remote server(s).
701 pseudo-attribute and to the other attribute values of the entries
704 operation is honored, which is performed by the frontend.
707 The LDAP backend provides basic proxying functionalities to many overlays.
710 overlay, described in
711 .BR slapo\-chain (5),
714 overlay, described in
715 .BR slapo\-translucent (5),
716 deserve a special mention.
718 Conversely, there are many overlays that are best used in conjunction
719 with the LDAP backend.
722 overlay allows caching of LDAP search requests (queries)
725 .BR slapo\-pcache (5)
729 overlay provides DN rewrite and attribute/objectClass mapping
730 capabilities to the underlying database.
738 default slapd configuration file
741 .BR slapd\-config (5),
743 .BR slapo\-chain (5),
744 .BR slapo\-pcache (5),
746 .BR slapo\-translucent (5),
750 Howard Chu, with enhancements by Pierangelo Masarati
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