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.
98 field is currently ignored.
99 There is no risk of giving away such values; they are only used to
101 The default is to use
103 with empty binddn and credentials,
104 which means that the related operations will be performed anonymously.
106 .B This identity is by no means implicitly used by the proxy
107 .B when the client connects anonymously.
111 This directive obsoletes
120 .B bindmethod=none|simple|sasl [binddn=<simple DN>] [credentials=<simple password>]
121 .B [saslmech=<SASL mech>] [secprops=<properties>] [realm=<realm>]
122 .B [authcId=<authentication ID>] [authzId=<authorization ID>]
123 .B [authz={native|proxyauthz}] [mode=<mode>] [flags=<flags>]
125 Allows to define the parameters of the authentication method that is
126 internally used by the proxy to authorize connections that are
127 authenticated by other databases.
128 The identity defined by this directive, according to the properties
129 associated to the authentication method, is supposed to have auth access
130 on the target server to attributes used on the proxy for authentication
131 and authorization, and to be allowed to authorize the users.
132 This requires to have
134 privileges on a wide set of DNs, e.g.
135 .BR authzTo=dn.subtree:"" ,
136 and the remote server to have
144 for details on these statements and for remarks and drawbacks about
146 The supported bindmethods are
148 \fBnone|simple|sasl\fP
152 is the default, i.e. no \fIidentity assertion\fP is performed.
154 The authz parameter is used to instruct the SASL bind to exploit
156 SASL authorization, if available; since connections are cached,
157 this should only be used when authorizing with a fixed identity
158 (e.g. by means of the
163 Otherwise, the default
165 is used, i.e. the proxyAuthz control is added to all operations.
167 The supported modes are:
169 \fB<mode> := {legacy|anonymous|none|self}\fP
175 is given, the proxy always authorizes that identity.
176 .B <authorization ID>
183 The former is supposed to be expanded by the remote server according
184 to the authz rules; see
187 In the latter case, whether or not the
189 prefix is present, the string must pass DN validation and normalization.
193 which implies that the proxy will either perform a simple bind as the
195 or a SASL bind as the
197 and assert the client's identity when it is not anonymous.
198 Direct binds are always proxied.
199 The other modes imply that the proxy will always either perform a simple bind
202 or a SASL bind as the
205 .BR idassert-authzFrom
206 rules (see below), in which case the operation will fail;
207 eventually, it will assert some other identity according to
209 Other identity assertion modes are
213 which respectively mean that the
220 which means that no proxyAuthz control will be used, so the
224 identity will be asserted.
225 For all modes that require the use of the
227 control, on the remote server the proxy identity must have appropriate
229 permissions, or the asserted identities must have appropriate
231 permissions. Note, however, that the ID assertion feature is mostly
232 useful when the asserted identities do not exist on the remote server.
236 \fBoverride,{prescriptive|non-prescriptive}\fP
240 flag is used, identity assertion takes place even when the database
241 is authorizing for the identity of the client, i.e. after binding
242 with the provided identity, and thus authenticating it, the proxy
243 performs the identity assertion using the configured identity and
244 authentication method.
248 flag is used (the default), operations fail with
249 \fIinappropriateAuthentication\fP
250 for those identities whose assertion is not allowed by the
251 .B idassert-authzFrom
255 flag is used, operations are performed anonymously for those identities
256 whose assertion is not allowed by the
257 .B idassert-authzFrom
260 This directive obsoletes
261 .BR idassert-authcDN ,
262 .BR idassert-passwd ,
265 .BR idassert-method .
269 .B idassert-authzFrom <authz-regexp>
270 if defined, selects what
272 identities are authorized to exploit the identity assertion feature.
275 follows the rules defined for the
282 for details on the syntax of this field.
285 .B proxy-whoami {NO|yes}
286 Turns on proxying of the WhoAmI extended operation. If this option is
287 given, back-ldap will replace slapd's original WhoAmI routine with its
288 own. On slapd sessions that were authenticated by back-ldap, the WhoAmI
289 request will be forwarded to the remote LDAP server. Other sessions will
290 be handled by the local slapd, as before. This option is mainly useful
291 in conjunction with Proxy Authorization.
294 .B rebind-as-user {NO|yes}
295 If this option is given, the client's bind credentials are remembered
296 for rebinds when chasing referrals. Useful when
297 \fBchase-referrals\fP is set to \fByes\fP, useless otherwise.
300 .B chase-referrals {YES|no}
301 enable/disable automatic referral chasing, which is delegated to the
302 underlying libldap, with rebinding eventually performed if the
303 \fBrebind-as-user\fP directive is used. The default is to chase referrals.
306 .B tls {[try-]start|[try-]propagate}
307 execute the start TLS extended operation when the connection is initialized;
308 only works if the URI directive protocol scheme is not \fBldaps://\fP.
309 \fBpropagate\fP issues the Start TLS exop only if the original
311 The \fBtry-\fP prefix instructs the proxy to continue operations
312 if start TLS failed; its use is highly deprecated.
315 .B t-f-support {NO|yes|discover}
316 enable if the remote server supports absolute filters
317 (see \fIdraft-zeilenga-ldap-t-f\fP for details).
320 support is detected by reading the remote server's root DSE.
322 .SH BACKWARD COMPATIBILITY
323 The LDAP backend has been heavily reworked between releases 2.2 and 2.3;
324 as a side-effect, some of the traditional directives have been
325 deprecated and should be no longer used.
328 .B server <hostname[:port]>
329 this directive is no longer supported. Use the
331 directive as described above.
334 .B acl-authcDN "<administrative DN for access control purposes>"
335 DN which is used to query the target server for acl checking; it
336 is supposed to have read access on the target server to attributes used
337 on the proxy for acl checking.
338 There is no risk of giving away such values; they are only used to
340 .B The acl-authcDN identity is by no means implicitly used by the proxy
341 .B when the client connects anonymously.
345 This directive is obsoleted by
347 and may dismissed in the future.
350 .B acl-passwd <password>
351 Password used with the
355 This directive is obsoleted by
357 and may be dismissed in the future.
360 .B idassert-authcDN "<administrative DN for proxyAuthz purposes>"
361 DN which is used to propagate the client's identity to the target
362 by means of the proxyAuthz control when the client does not
363 belong to the DIT fragment that is being proxied by back-ldap.
364 This directive is obsoleted by
366 and may be dismissed in the future.
369 .B idassert-passwd <password>
370 Password used with the
373 This directive is obsoleted by
375 and may be dismissed in the future.
378 .B idassert-mode <mode> [<flags>]
380 .I identity assertion
382 This directive is obsoleted by
384 and may be dismissed in the future.
387 .B idassert-method <method> [<saslargs>]
388 This directive is obsoleted by
390 and may be dismissed in the future.
393 .B suffixmassage, map, rewrite*
394 These directives are no longer supported by back-ldap; their
395 functionality is now delegated to the
397 overlay. Essentially, add a statement
401 first, and prefix all rewrite/map statements with
403 to obtain the original behavior.
407 .\" However, to ease update from existing configurations, back-ldap still
408 .\" recognizes them and automatically instantiates the
410 .\" overlay if available and not instantiated yet.
411 .\" This behavior may change in the future.
416 backend does not honor all ACL semantics as described in
417 .BR slapd.access (5).
418 In general, access checking is delegated to the remote server(s).
423 pseudo-attribute and to the other attribute values of the entries
426 operation is honored, which is performed by the frontend.
429 The LDAP backend provides basic proxying functionalities to many overlays.
432 overlay, described in
433 .BR slapo\-chain (5),
436 overlay, described in
437 .BR slapo\-translucent (5),
438 deserve a special mention.
440 Conversely, there are many overlays that are best used in conjunction
441 with the LDAP backend.
444 overlay allows caching of LDAP search requests (queries)
447 .BR slapo\-pcache (5)
451 overlay provides DN rewrite and attribute/objectClass mapping
452 capabilities to the underlying database.
460 default slapd configuration file
464 .BR slapo\-chain (5),
465 .BR slapo\-pcache (5),
467 .BR slapo\-translucent (5),
471 Howard Chu, with enhancements by Pierangelo Masarati
projects / openldap / blob