1 .TH SLAPD-LDAP 5 "RELEASEDATE" "OpenLDAP LDVERSION"
2 .\" Copyright 1998-2005 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
43 options apply to the LDAP backend database.
44 That is, they must follow a "database ldap" line and come before any
45 subsequent "backend" or "database" lines.
46 Other database options are described in the
50 Note: In early versions of back-ldap it was recommended to always set
63 This is because operational attributes related to entry creation and
64 modification should not be proxied, as they could be mistakenly written
65 to the target server(s), generating an error.
66 The current implementation automatically sets lastmod to off, so its use
67 is redundant and should be omitted, because the lastmod directive will
68 be deprecated in the future.
72 LDAP server to use. Multiple URIs can be set in in a single
74 argument, resulting in the underlying library automatically
75 call the first server of the list that responds, e.g.
77 \fBuri "ldap://host/ ldap://backup-host"\fP
79 The URI list is space- or comma-separated.
80 This statement is mandatory.
82 .\".B server <hostport>
83 .\"Obsolete option; same as `uri ldap://<hostport>/'.
87 .B bindmethod=simple|sasl [binddn=<simple DN>] [credentials=<simple password>]
88 .B [saslmech=<SASL mech>] [secprops=<properties>] [realm=<realm>]
89 .B [authcId=<authentication ID>] [authzId=<authorization ID>]
91 Allows to define the parameters of the authentication method that is
92 internally used by the proxy to collect info related to access control.
93 The identity defined by this directive, according to the properties
94 associated to the authentication method, is supposed to have read access
95 on the target server to attributes used on the proxy for ACL checking.
96 There is no risk of giving away such values; they are only used to
100 bind, with empty \fIbinddn\fP and \fIcredentials\fP,
101 which means that the related operations will be performed anonymously.
103 .B This identity is by no means implicitly used by the proxy
104 .B when the client connects anonymously.
107 feature, instead, in some cases can be crafted to implement that behavior,
108 which is \fIintrinsically unsafe and should be used with extreme care\fP.
109 This directive obsoletes
118 .B bindmethod=none|simple|sasl [binddn=<simple DN>] [credentials=<simple password>]
119 .B [saslmech=<SASL mech>] [secprops=<properties>] [realm=<realm>]
120 .B [authcId=<authentication ID>] [authzId=<authorization ID>]
121 .B [authz={native|proxyauthz}] [mode=<mode>] [flags=<flags>]
123 Allows to define the parameters of the authentication method that is
124 internally used by the proxy to authorize connections that are
125 authenticated by other databases.
126 The identity defined by this directive, according to the properties
127 associated to the authentication method, is supposed to have auth access
128 on the target server to attributes used on the proxy for authentication
129 and authorization, and to be allowed to authorize the users.
130 This requires to have
132 privileges on a wide set of DNs, e.g.
133 .BR authzTo=dn.subtree:"" ,
134 and the remote server to have
142 for details on these statements and for remarks and drawbacks about
144 The supported bindmethods are
146 \fBnone|simple|sasl\fP
150 is the default, i.e. no \fIidentity assertion\fP is performed.
152 The authz parameter is used to instruct the SASL bind to exploit
154 SASL authorization, if available; since connections are cached,
155 this should only be used when authorizing with a fixed identity
156 (e.g. by means of the
161 Otherwise, the default
163 is used, i.e. the proxyAuthz control is added to all operations.
165 The supported modes are:
167 \fB<mode> := {legacy|anonymous|none|self}\fP
173 is given, the proxy always authorizes that identity.
174 .B <authorization ID>
181 The former is supposed to be expanded by the remote server according
182 to the authz rules; see
185 In the latter case, whether or not the
187 prefix is present, the string must pass DN validation and normalization.
191 which implies that the proxy will either perform a simple bind as the
193 or a SASL bind as the
195 and assert the client's identity when it is not anonymous.
196 Direct binds are always proxied.
197 The other modes imply that the proxy will always either perform a simple bind
200 or a SASL bind as the
203 .BR idassert-authzFrom
204 rules (see below), in which case the operation will fail;
205 eventually, it will assert some other identity according to
207 Other identity assertion modes are
211 which respectively mean that the
218 which means that no proxyAuthz control will be used, so the
222 identity will be asserted.
223 For all modes that require the use of the
225 control, on the remote server the proxy identity must have appropriate
227 permissions, or the asserted identities must have appropriate
229 permissions. Note, however, that the ID assertion feature is mostly
230 useful when the asserted identities do not exist on the remote server.
234 \fBoverride,{prescriptive|non-prescriptive}\fP
238 flag is used, identity assertion takes place even when the database
239 is authorizing for the identity of the client, i.e. after binding
240 with the provided identity, and thus authenticating it, the proxy
241 performs the identity assertion using the configured identity and
242 authentication method.
246 flag is used (the default), operations fail with
247 \fIinappropriateAuthentication\fP
248 for those identities whose assertion is not allowed by the
249 .B idassert-authzFrom
253 flag is used, operations are performed anonymously for those identities
254 whose assertion is not allowed by the
255 .B idassert-authzFrom
258 This directive obsoletes
259 .BR idassert-authcDN ,
260 .BR idassert-passwd ,
263 .BR idassert-method .
267 .B idassert-authzFrom <authz-regexp>
268 if defined, selects what
270 identities are authorized to exploit the identity assertion feature.
273 follows the rules defined for the
280 for details on the syntax of this field.
283 .B proxy-whoami {NO|yes}
284 Turns on proxying of the WhoAmI extended operation. If this option is
285 given, back-ldap will replace slapd's original WhoAmI routine with its
286 own. On slapd sessions that were authenticated by back-ldap, the WhoAmI
287 request will be forwarded to the remote LDAP server. Other sessions will
288 be handled by the local slapd, as before. This option is mainly useful
289 in conjunction with Proxy Authorization.
292 .B rebind-as-user {NO|yes}
293 If this option is given, the client's bind credentials are remembered
294 for rebinds when chasing referrals. Useful when
295 \fBchase-referrals\fP is set to \fByes\fP, useless otherwise.
298 .B chase-referrals {YES|no}
299 enable/disable automatic referral chasing, which is delegated to the
300 underlying libldap, with rebinding eventually performed if the
301 \fBrebind-as-user\fP directive is used. The default is to chase referrals.
304 .B tls {[try-]start|[try-]propagate}
305 execute the StartTLS extended operation when the connection is initialized;
306 only works if the URI directive protocol scheme is not \fBldaps://\fP.
307 \fBpropagate\fP issues the StartTLS operation only if the original
309 The \fBtry-\fP prefix instructs the proxy to continue operations
310 if the StartTLS operation failed; its use is highly deprecated.
313 .B t-f-support {NO|yes|discover}
314 enable if the remote server supports absolute filters
315 (see \fIdraft-zeilenga-ldap-t-f\fP for details).
318 support is detected by reading the remote server's root DSE.
321 .B timeout [{add|delete|modify|modrdn}=]<val> [...]
322 This directive allows to set per-operation timeouts.
323 If no operation is specified, it affects all.
324 Currently, only write operations are addressed, because searches
325 can already be limited by means of the
329 for details), and other operations are not supposed to incur into the
331 Note: if the timelimit is exceeded, the operation is abandoned;
332 the protocol does not provide any means to rollback the operation,
333 so the client will not know if the operation eventually succeeded or not.
336 .B idle-timeout <time>
337 This directive causes a cached connection to be dropped an recreated
338 after it has been idle for the specified time.
340 .SH BACKWARD COMPATIBILITY
341 The LDAP backend has been heavily reworked between releases 2.2 and 2.3;
342 as a side-effect, some of the traditional directives have been
343 deprecated and should be no longer used.
346 .B server <hostname[:port]>
347 this directive is no longer supported. Use the
349 directive as described above.
352 .B acl-authcDN "<administrative DN for access control purposes>"
353 DN which is used to query the target server for acl checking; it
354 is supposed to have read access on the target server to attributes used
355 on the proxy for acl checking.
356 There is no risk of giving away such values; they are only used to
358 .B The acl-authcDN identity is by no means implicitly used by the proxy
359 .B when the client connects anonymously.
363 This directive is obsoleted by
365 and may dismissed in the future.
368 .B acl-passwd <password>
369 Password used with the
373 This directive is obsoleted by
375 and may be dismissed in the future.
378 .B idassert-authcDN "<administrative DN for proxyAuthz purposes>"
379 DN which is used to propagate the client's identity to the target
380 by means of the proxyAuthz control when the client does not
381 belong to the DIT fragment that is being proxied by back-ldap.
382 This directive is obsoleted by
384 and may be dismissed in the future.
387 .B idassert-passwd <password>
388 Password used with the
391 This directive is obsoleted by
393 and may be dismissed in the future.
396 .B idassert-mode <mode> [<flags>]
398 .I identity assertion
400 This directive is obsoleted by
402 and may be dismissed in the future.
405 .B idassert-method <method> [<saslargs>]
406 This directive is obsoleted by
408 and may be dismissed in the future.
411 .B suffixmassage, map, rewrite*
412 These directives are no longer supported by back-ldap; their
413 functionality is now delegated to the
415 overlay. Essentially, add a statement
419 first, and prefix all rewrite/map statements with
421 to obtain the original behavior.
425 .\" However, to ease update from existing configurations, back-ldap still
426 .\" recognizes them and automatically instantiates the
428 .\" overlay if available and not instantiated yet.
429 .\" This behavior may change in the future.
434 backend does not honor all ACL semantics as described in
435 .BR slapd.access (5).
436 In general, access checking is delegated to the remote server(s).
441 pseudo-attribute and to the other attribute values of the entries
444 operation is honored, which is performed by the frontend.
447 The LDAP backend provides basic proxying functionalities to many overlays.
450 overlay, described in
451 .BR slapo\-chain (5),
454 overlay, described in
455 .BR slapo\-translucent (5),
456 deserve a special mention.
458 Conversely, there are many overlays that are best used in conjunction
459 with the LDAP backend.
462 overlay allows caching of LDAP search requests (queries)
465 .BR slapo\-pcache (5)
469 overlay provides DN rewrite and attribute/objectClass mapping
470 capabilities to the underlying database.
478 default slapd configuration file
482 .BR slapo\-chain (5),
483 .BR slapo\-pcache (5),
485 .BR slapo\-translucent (5),
489 Howard Chu, with enhancements by Pierangelo Masarati
projects / openldap / blob