1 .TH SLAPD-LDAP 5 "RELEASEDATE" "OpenLDAP LDVERSION"
2 .\" Copyright 1998-2006 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
41 Note: When looping back to the same instance of \fBslapd\fP(8),
42 each connection requires a new thread; as a consequence, \fBslapd\fP(8)
43 must be compiled with thread support, and the \fBthreads\fP parameter
44 may need some tuning; in those cases, one may consider using
45 \fBslapd-relay\fP(5) instead, which performs the relayed operation
46 internally and thus reuses the same connection.
51 options apply to the LDAP backend database.
52 That is, they must follow a "database ldap" line and come before any
53 subsequent "backend" or "database" lines.
54 Other database options are described in the
59 Note: In early versions of back-ldap it was recommended to always set
72 This is because operational attributes related to entry creation and
73 modification should not be proxied, as they could be mistakenly written
74 to the target server(s), generating an error.
75 The current implementation automatically sets lastmod to off, so its use
76 is redundant and should be omitted, because the lastmod directive will
77 be deprecated in the future.
81 LDAP server to use. Multiple URIs can be set in in a single
83 argument, resulting in the underlying library automatically
84 call the first server of the list that responds, e.g.
86 \fBuri "ldap://host/ ldap://backup-host"\fP
88 The URI list is space- or comma-separated.
89 This statement is mandatory.
91 .\".B server <hostport>
92 .\"Obsolete option; same as `uri ldap://<hostport>/'.
96 .B bindmethod=simple|sasl [binddn=<simple DN>] [credentials=<simple password>]
97 .B [saslmech=<SASL mech>] [secprops=<properties>] [realm=<realm>]
98 .B [authcId=<authentication ID>] [authzId=<authorization ID>]
100 Allows to define the parameters of the authentication method that is
101 internally used by the proxy to collect info related to access control.
102 The identity defined by this directive, according to the properties
103 associated to the authentication method, is supposed to have read access
104 on the target server to attributes used on the proxy for ACL checking.
105 There is no risk of giving away such values; they are only used to
107 The default is to use
109 bind, with empty \fIbinddn\fP and \fIcredentials\fP,
110 which means that the related operations will be performed anonymously.
112 .B This identity is by no means implicitly used by the proxy
113 .B when the client connects anonymously.
116 feature, instead, in some cases can be crafted to implement that behavior,
117 which is \fIintrinsically unsafe and should be used with extreme care\fP.
118 This directive obsoletes
127 .B bindmethod=none|simple|sasl [binddn=<simple DN>] [credentials=<simple password>]
128 .B [saslmech=<SASL mech>] [secprops=<properties>] [realm=<realm>]
129 .B [authcId=<authentication ID>] [authzId=<authorization ID>]
130 .B [authz={native|proxyauthz}] [mode=<mode>] [flags=<flags>]
132 Allows to define the parameters of the authentication method that is
133 internally used by the proxy to authorize connections that are
134 authenticated by other databases.
135 The identity defined by this directive, according to the properties
136 associated to the authentication method, is supposed to have auth access
137 on the target server to attributes used on the proxy for authentication
138 and authorization, and to be allowed to authorize the users.
139 This requires to have
141 privileges on a wide set of DNs, e.g.
142 .BR authzTo=dn.subtree:"" ,
143 and the remote server to have
151 for details on these statements and for remarks and drawbacks about
153 The supported bindmethods are
155 \fBnone|simple|sasl\fP
159 is the default, i.e. no \fIidentity assertion\fP is performed.
161 The authz parameter is used to instruct the SASL bind to exploit
163 SASL authorization, if available; since connections are cached,
164 this should only be used when authorizing with a fixed identity
165 (e.g. by means of the
170 Otherwise, the default
172 is used, i.e. the proxyAuthz control is added to all operations.
174 The supported modes are:
176 \fB<mode> := {legacy|anonymous|none|self}\fP
182 is given, the proxy always authorizes that identity.
183 .B <authorization ID>
190 The former is supposed to be expanded by the remote server according
191 to the authz rules; see
194 In the latter case, whether or not the
196 prefix is present, the string must pass DN validation and normalization.
200 which implies that the proxy will either perform a simple bind as the
202 or a SASL bind as the
204 and assert the client's identity when it is not anonymous.
205 Direct binds are always proxied.
206 The other modes imply that the proxy will always either perform a simple bind
209 or a SASL bind as the
212 .BR idassert-authzFrom
213 rules (see below), in which case the operation will fail;
214 eventually, it will assert some other identity according to
216 Other identity assertion modes are
220 which respectively mean that the
227 which means that no proxyAuthz control will be used, so the
231 identity will be asserted.
232 For all modes that require the use of the
234 control, on the remote server the proxy identity must have appropriate
236 permissions, or the asserted identities must have appropriate
238 permissions. Note, however, that the ID assertion feature is mostly
239 useful when the asserted identities do not exist on the remote server.
243 \fBoverride,{prescriptive|non-prescriptive}\fP
247 flag is used, identity assertion takes place even when the database
248 is authorizing for the identity of the client, i.e. after binding
249 with the provided identity, and thus authenticating it, the proxy
250 performs the identity assertion using the configured identity and
251 authentication method.
255 flag is used (the default), operations fail with
256 \fIinappropriateAuthentication\fP
257 for those identities whose assertion is not allowed by the
258 .B idassert-authzFrom
262 flag is used, operations are performed anonymously for those identities
263 whose assertion is not allowed by the
264 .B idassert-authzFrom
267 This directive obsoletes
268 .BR idassert-authcDN ,
269 .BR idassert-passwd ,
272 .BR idassert-method .
276 .B idassert-authzFrom <authz-regexp>
277 if defined, selects what
279 identities are authorized to exploit the identity assertion feature.
282 follows the rules defined for the
289 for details on the syntax of this field.
292 .B proxy-whoami {NO|yes}
293 Turns on proxying of the WhoAmI extended operation. If this option is
294 given, back-ldap will replace slapd's original WhoAmI routine with its
295 own. On slapd sessions that were authenticated by back-ldap, the WhoAmI
296 request will be forwarded to the remote LDAP server. Other sessions will
297 be handled by the local slapd, as before. This option is mainly useful
298 in conjunction with Proxy Authorization.
301 .B rebind-as-user {NO|yes}
302 If this option is given, the client's bind credentials are remembered
303 for rebinds when chasing referrals. Useful when
304 \fBchase-referrals\fP is set to \fByes\fP, useless otherwise.
307 .B chase-referrals {YES|no}
308 enable/disable automatic referral chasing, which is delegated to the
309 underlying libldap, with rebinding eventually performed if the
310 \fBrebind-as-user\fP directive is used. The default is to chase referrals.
313 .B tls {[try-]start|[try-]propagate}
314 execute the StartTLS extended operation when the connection is initialized;
315 only works if the URI directive protocol scheme is not \fBldaps://\fP.
316 \fBpropagate\fP issues the StartTLS operation only if the original
318 The \fBtry-\fP prefix instructs the proxy to continue operations
319 if the StartTLS operation failed; its use is highly deprecated.
322 .B t-f-support {NO|yes|discover}
323 enable if the remote server supports absolute filters
324 (see \fIdraft-zeilenga-ldap-t-f\fP for details).
327 support is detected by reading the remote server's root DSE.
330 .B timeout [{add|delete|modify|modrdn}=]<val> [...]
331 This directive allows to set per-operation timeouts.
332 If no operation is specified, it affects all.
333 Currently, only write operations are addressed, because searches
334 can already be limited by means of the
338 for details), and other operations are not supposed to incur into the
340 Note: if the timelimit is exceeded, the operation is abandoned;
341 the protocol does not provide any means to rollback the operation,
342 so the client will not know if the operation eventually succeeded or not.
345 .B idle-timeout <time>
346 This directive causes a cached connection to be dropped an recreated
347 after it has been idle for the specified time.
351 This directive causes a cached connection to be dropped an recreated
352 after a given ttl, regardless of being idle or not.
354 .SH BACKWARD COMPATIBILITY
355 The LDAP backend has been heavily reworked between releases 2.2 and 2.3;
356 as a side-effect, some of the traditional directives have been
357 deprecated and should be no longer used, as they might disappear
361 .B server <hostname[:port]>
362 this directive is no longer supported. Use the
364 directive as described above.
367 .B acl-authcDN "<administrative DN for access control purposes>"
368 DN which is used to query the target server for acl checking; it
369 is supposed to have read access on the target server to attributes used
370 on the proxy for acl checking.
371 There is no risk of giving away such values; they are only used to
373 .B The acl-authcDN identity is by no means implicitly used by the proxy
374 .B when the client connects anonymously.
378 This directive is obsoleted by the
382 when \fIbindmethod\fP=\fBsimple\fP, and will be dismissed in the future.
385 .B acl-passwd <password>
386 Password used with the above
389 This directive is obsoleted by the
393 when \fIbindmethod\fP=\fBsimple\fP, and will be dismissed in the future.
396 .B idassert-authcDN "<administrative DN for proxyAuthz purposes>"
397 DN which is used to propagate the client's identity to the target
398 by means of the proxyAuthz control when the client does not
399 belong to the DIT fragment that is being proxied by back-ldap.
400 This directive is obsoleted by the
404 when \fIbindmethod\fP=\fBsimple\fP, and will be dismissed in the future.
407 .B idassert-passwd <password>
408 Password used with the
411 This directive is obsoleted by the
415 when \fIbindmethod\fP=\fBsimple\fP, and will be dismissed in the future.
418 .B idassert-mode <mode> [<flags>]
420 .I identity assertion
422 This directive is obsoleted by the
426 and will be dismissed in the future.
429 .B idassert-method <method> [<saslargs>]
430 This directive is obsoleted by the
434 and will be dismissed in the future.
437 .B suffixmassage, map, rewrite*
438 These directives are no longer supported by back-ldap; their
439 functionality is now delegated to the
441 overlay. Essentially, add a statement
445 first, and prefix all rewrite/map statements with
447 to obtain the original behavior.
451 .\" However, to ease update from existing configurations, back-ldap still
452 .\" recognizes them and automatically instantiates the
454 .\" overlay if available and not instantiated yet.
455 .\" This behavior may change in the future.
460 backend does not honor all ACL semantics as described in
461 .BR slapd.access (5).
462 In general, access checking is delegated to the remote server(s).
467 pseudo-attribute and to the other attribute values of the entries
470 operation is honored, which is performed by the frontend.
473 The LDAP backend provides basic proxying functionalities to many overlays.
476 overlay, described in
477 .BR slapo\-chain (5),
480 overlay, described in
481 .BR slapo\-translucent (5),
482 deserve a special mention.
484 Conversely, there are many overlays that are best used in conjunction
485 with the LDAP backend.
488 overlay allows caching of LDAP search requests (queries)
491 .BR slapo\-pcache (5)
495 overlay provides DN rewrite and attribute/objectClass mapping
496 capabilities to the underlying database.
504 default slapd configuration file
508 .BR slapo\-chain (5),
509 .BR slapo\-pcache (5),
511 .BR slapo\-translucent (5),
515 Howard Chu, with enhancements by Pierangelo Masarati
projects / openldap / blob