1SLAPD-LDAP(5) File Formats Manual SLAPD-LDAP(5)
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6 slapd-ldap - LDAP backend to slapd
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9 /etc/openldap/slapd.conf
10
12 The LDAP backend to slapd(8) is not an actual database; instead it acts
13 as a proxy to forward incoming requests to another LDAP server. While
14 processing requests it will also chase referrals, so that referrals are
15 fully processed instead of being returned to the slapd client.
16 Sessions that explicitly Bind to the back-ldap database always create
18 their own private connection to the remote LDAP server. Anonymous ses‐
19 sions will share a single anonymous connection to the remote server.
20 For sessions bound through other mechanisms, all sessions with the same
21 DN will share the same connection. This connection pooling strategy can
22 enhance the proxy's efficiency by reducing the overhead of repeatedly
23 making/breaking multiple connections.
24 The ldap database can also act as an information service, i.e. the
26 identity of locally authenticated clients is asserted to the remote
27 server, possibly in some modified form. For this purpose, the proxy
28 binds to the remote server with some administrative identity, and, if
29 required, authorizes the asserted identity. See the idassert-* rules
30 below. The administrative identity of the proxy, on the remote server,
31 must be allowed to authorize by means of appropriate authzTo rules; see
32 slapd.conf(5) for details.
33 The proxy instance of slapd(8) must contain schema information for the
35 attributes and objectClasses used in filters, request DNs and request-
36 related data in general. It should also contain schema information for
37 the data returned by the proxied server. It is the responsibility of
38 the proxy administrator to keep the schema of the proxy lined up with
39 that of the proxied server.
40 Note: When looping back to the same instance of slapd(8), each connec‐
43 tion requires a new thread; as a consequence, slapd(8) must be compiled
44 with thread support, and the threads parameter may need some tuning; in
45 those cases, one may consider using slapd-relay(5) instead, which per‐
46 forms the relayed operation internally and thus reuses the same connec‐
47 tion.
48
51 These slapd.conf options apply to the LDAP backend database. That is,
52 they must follow a "database ldap" line and come before any subsequent
53 "backend" or "database" lines. Other database options are described in
54 the slapd.conf(5) manual page.
55 Note: In early versions of back-ldap it was recommended to always set
58 lastmod off
60 for ldap and meta databases. This was required because operational
62 attributes related to entry creation and modification should not be
63 proxied, as they could be mistakenly written to the target server(s),
64 generating an error. The current implementation automatically sets
65 lastmod to off, so its use is redundant and should be omitted.
66 uri <ldapurl>
69 LDAP server to use. Multiple URIs can be set in a single lda‐
70 purl argument, resulting in the underlying library automatically
71 calling the first server of the list that responds, e.g.
72 uri "ldap://host/ ldap://backup-host/"
74 The URI list is space- or comma-separated. Whenever the server
76 that responds is not the first one in the list, the list is
77 rearranged and the responsive server is moved to the head, so
78 that it will be first contacted the next time a connection needs
79 to be created.
80 acl-bind bindmethod=simple|sasl [binddn=<simple DN>]
82 [credentials=<simple password>] [saslmech=<SASL mech>]
83 [secprops=<properties>] [realm=<realm>] [authcId=<authentication
84 ID>] [authzId=<authorization ID>] [starttls=no|yes|critical]
85 [tls_cert=<file>] [tls_key=<file>] [tls_cacert=<file>]
86 [tls_cacertdir=<path>] [tls_reqcert=never|allow|try|demand]
87 [tls_cipher_suite=<ciphers>]
88 [tls_protocol_min=<major>[.<minor>]]
89 [tls_crlcheck=none|peer|all]
90 Allows one to define the parameters of the authentication method
91 that is internally used by the proxy to collect info related to
92 access control, and whenever an operation occurs with the
93 identity of the rootdn of the LDAP proxy database. The identity
94 defined by this directive, according to the properties
95 associated to the authentication method, is supposed to have
96 read access on the target server to attributes used on the proxy
97 for ACL checking.
98 There is no risk of giving away such values; they are only used
100 to check permissions. The default is to use simple bind, with
101 empty binddn and credentials, which means that the related
102 operations will be performed anonymously. If not set, and if
103 idassert-bind is defined, this latter identity is used instead.
104 See idassert-bind for details.
105 The connection between the proxy database and the remote server
107 associated to this identity is cached regardless of the lifespan
108 of the client-proxy connection that first established it.
109 This identity is not implicitly used by the proxy when the
111 client connects anonymously. The idassert-bind feature,
112 instead, in some cases can be crafted to implement that
113 behavior, which is intrinsically unsafe and should be used with
114 extreme care. This directive obsoletes acl-authcDN, and
115 acl-passwd.
116 The TLS settings default to the same as the main slapd TLS
118 settings, except for tls_reqcert which defaults to "demand".
119 cancel {ABANDON|ignore|exop[-discover]}
122 Defines how to handle operation cancellation. By default,
123 abandon is invoked, so the operation is abandoned immediately.
124 If set to ignore, no action is taken and any further response is
125 ignored; this may result in further response messages to be
126 queued for that connection, so it is recommended that long
127 lasting connections are timed out either by idle-timeout or
128 conn-ttl, so that resources eventually get released. If set to
129 exop, a cancel operation (RFC 3909) is issued, resulting in the
130 cancellation of the current operation; the cancel operation
131 waits for remote server response, so its use may not be
132 recommended. If set to exop-discover, support of the cancel
133 extended operation is detected by reading the remote server's
134 root DSE.
135 chase-referrals {YES|no}
138 enable/disable automatic referral chasing, which is delegated to
139 the underlying libldap, with rebinding eventually performed if
140 the rebind-as-user directive is used. The default is to chase
141 referrals.
142 conn-ttl <time>
145 This directive causes a cached connection to be dropped and
146 recreated after a given ttl, regardless of being idle or not.
147 idassert-authzFrom <authz-regexp>
150 if defined, selects what local identities are authorized to
151 exploit the identity assertion feature. The string <authz-
152 regexp> mostly follows the rules defined for the authzFrom
153 attribute. See slapd.conf(5), section related to authz-policy,
154 for details on the syntax of this field. This parameter differs
155 from the documented behavior in relation to the meaning of *,
156 which in this case allows anonymous rather than denies.
157 idassert-bind bindmethod=none|simple|sasl [binddn=<simple DN>]
160 [credentials=<simple password>] [saslmech=<SASL mech>]
161 [secprops=<properties>] [realm=<realm>] [authcId=<authentication
162 ID>] [authzId=<authorization ID>] [authz={native|proxyauthz}]
163 [mode=<mode>] [flags=<flags>] [starttls=no|yes|critical]
164 [tls_cert=<file>] [tls_key=<file>] [tls_cacert=<file>]
165 [tls_cacertdir=<path>] [tls_reqcert=never|allow|try|demand]
166 [tls_cipher_suite=<ciphers>] [tls_protocol_min=<version>]
167 [tls_crlcheck=none|peer|all]
168 Allows one to define the parameters of the authentication method
169 that is internally used by the proxy to authorize connections
170 that are authenticated by other databases. Direct binds are
171 always proxied without any idassert handling.
172 The identity defined by this directive, according to the
174 properties associated to the authentication method, is supposed
175 to have auth access on the target server to attributes used on
176 the proxy for authentication and authorization, and to be
177 allowed to authorize the users. This requires to have
178 proxyAuthz privileges on a wide set of DNs, e.g.
179 authzTo=dn.subtree:"", and the remote server to have
180 authz-policy set to to or both. See slapd.conf(5) for details
181 on these statements and for remarks and drawbacks about their
182 usage. The supported bindmethods are
183 none|simple|sasl
185 where none is the default, i.e. no identity assertion is
187 performed.
188 The authz parameter is used to instruct the SASL bind to exploit
190 native SASL authorization, if available; since connections are
191 cached, this should only be used when authorizing with a fixed
192 identity (e.g. by means of the authzDN or authzID parameters).
193 Otherwise, the default proxyauthz is used, i.e. the proxyAuthz
194 control (Proxied Authorization, RFC 4370) is added to all
195 operations.
196 The supported modes are:
198 <mode> := {legacy|anonymous|none|self}
200 If <mode> is not present, and authzId is given, the proxy always
202 authorizes that identity. <authorization ID> can be
203 u:<user>
205 [dn:]<DN>
207 The former is supposed to be expanded by the remote server
209 according to the authz rules; see slapd.conf(5) for details. In
210 the latter case, whether or not the dn: prefix is present, the
211 string must pass DN validation and normalization.
212 The default mode is legacy, which implies that the proxy will
214 either perform a simple bind as the authcDN or a SASL bind as
215 the authcID and assert the client's identity when it is not
216 anonymous. The other modes imply that the proxy will always
217 either perform a simple bind as the authcDN or a SASL bind as
218 the authcID, unless restricted by idassert-authzFrom rules (see
219 below), in which case the operation will fail; eventually, it
220 will assert some other identity according to <mode>. Other
221 identity assertion modes are anonymous and self, which
222 respectively mean that the empty or the client's identity will
223 be asserted; none, which means that no proxyAuthz control will
224 be used, so the authcDN or the authcID identity will be
225 asserted. For all modes that require the use of the proxyAuthz
226 control, on the remote server the proxy identity must have
227 appropriate authzTo permissions, or the asserted identities must
228 have appropriate authzFrom permissions. Note, however, that the
229 ID assertion feature is mostly useful when the asserted
230 identities do not exist on the remote server.
231 Flags can be
233 override,[non-]prescriptive,proxy-authz-[non-]critical
235 When the override flag is used, identity assertion takes place
237 even when the database is authorizing for the identity of the
238 client, i.e. after binding with the provided identity, and thus
239 authenticating it, the proxy performs the identity assertion
240 using the configured identity and authentication method.
241 When the prescriptive flag is used (the default), operations
243 fail with inappropriateAuthentication for those identities whose
244 assertion is not allowed by the idassert-authzFrom patterns. If
245 the non-prescriptive flag is used, operations are performed
246 anonymously for those identities whose assertion is not allowed
247 by the idassert-authzFrom patterns.
248 When the proxy-authz-non-critical flag is used (the default),
250 the proxyAuthz control is not marked as critical, in violation
251 of RFC 4370. Use of proxy-authz-critical is recommended.
252 The TLS settings default to the same as the main slapd TLS
254 settings, except for tls_reqcert which defaults to "demand".
255 The identity associated to this directive is also used for
257 privileged operations whenever idassert-bind is defined and
258 acl-bind is not. See acl-bind for details.
259 This directive obsoletes idassert-authcDN, idassert-passwd,
261 idassert-mode, and idassert-method.
262 idassert-passthru <authz-regexp>
265 if defined, selects what local identities bypass the identity
266 assertion feature. Those identities need to be known by the
267 remote host. The string <authz-regexp> follows the rules
268 defined for the authzFrom attribute. See slapd.conf(5), section
269 related to authz-policy, for details on the syntax of this
270 field.
271 idle-timeout <time>
275 This directive causes a cached connection to be dropped an
276 recreated after it has been idle for the specified time.
277 keepalive <idle>:<probes>:<interval>
280 The keepalive parameter sets the values of idle, probes, and
281 interval used to check whether a socket is alive; idle is the
282 number of seconds a connection needs to remain idle before TCP
283 starts sending keepalive probes; probes is the maximum number of
284 keepalive probes TCP should send before dropping the connection;
285 interval is interval in seconds between individual keepalive
286 probes. Only some systems support the customization of these
287 values; the keepalive parameter is ignored otherwise, and
288 system-wide settings are used.
289 network-timeout <time>
292 Sets the network timeout value after which poll(2)/select(2)
293 following a connect(2) returns in case of no activity. The
294 value is in seconds, and it can be specified as for
295 idle-timeout.
296 norefs <NO|yes>
299 If yes, do not return search reference responses. By default,
300 they are returned unless request is LDAPv2.
301 omit-unknown-schema <NO|yes>
304 If yes, do not return objectClasses or attributes that are not
305 known to the local server. The default is to return all schema
306 elements.
307 noundeffilter <NO|yes>
310 If yes, return success instead of searching if a filter is
311 undefined or contains undefined portions. By default, the
312 search is propagated after replacing undefined portions with
313 (!(objectClass=*)), which corresponds to the empty result set.
314 onerr {CONTINUE|stop}
317 This directive allows one to select the behavior in case an
318 error is returned by the remote server during a search. The
319 default, continue, consists in returning success. If the value
320 is set to stop, the error is returned to the client.
321 protocol-version {0,2,3}
324 This directive indicates what protocol version must be used to
325 contact the remote server. If set to 0 (the default), the proxy
326 uses the same protocol version used by the client, otherwise the
327 requested protocol is used. The proxy returns
328 unwillingToPerform if an operation that is incompatible with the
329 requested protocol is attempted.
330 proxy-whoami {NO|yes}
333 Turns on proxying of the WhoAmI extended operation. If this
334 option is given, back-ldap will replace slapd's original WhoAmI
335 routine with its own. On slapd sessions that were authenticated
336 by back-ldap, the WhoAmI request will be forwarded to the remote
337 LDAP server. Other sessions will be handled by the local slapd,
338 as before. This option is mainly useful in conjunction with
339 Proxy Authorization.
340 quarantine <interval>,<num>[;<interval>,<num>[...]]
343 Turns on quarantine of URIs that returned LDAP_UNAVAILABLE, so
344 that an attempt to reconnect only occurs at given intervals
345 instead of any time a client requests an operation. The pattern
346 is: retry only after at least interval seconds elapsed since
347 last attempt, for exactly num times; then use the next pattern.
348 If num for the last pattern is "+", it retries forever;
349 otherwise, no more retries occur. The process can be restarted
350 by resetting the olcDbQuarantine attribute of the database entry
351 in the configuration backend.
352 rebind-as-user {NO|yes}
355 If this option is given, the client's bind credentials are
356 remembered for rebinds, when trying to re-establish a broken
357 connection, or when chasing a referral, if chase-referrals is
358 set to yes.
359 session-tracking-request {NO|yes}
362 Adds session tracking control for all requests. The client's IP
363 and hostname, and the identity associated to each request, if
364 known, are sent to the remote server for informational purposes.
365 This directive is incompatible with setting protocol-version to
366 2.
367 single-conn {NO|yes}
370 Discards current cached connection when the client rebinds.
371 t-f-support {NO|yes|discover}
374 enable if the remote server supports absolute filters (see RFC
375 4526 for details). If set to discover, support is detected by
376 reading the remote server's root DSE.
377 timeout [<op>=]<val> [...]
380 This directive allows one to set per-operation timeouts.
381 Operations can be
382 <op> ::= bind, add, delete, modrdn, modify, compare, search
384 The overall duration of the search operation is controlled
386 either by the timelimit parameter or by server-side enforced
387 time limits (see timelimit and limits in slapd.conf(5) for
388 details). This timeout parameter controls how long the target
389 can be irresponsive before the operation is aborted. Timeout is
390 meaningless for the remaining operations, unbind and abandon,
391 which do not imply any response, while it is not yet implemented
392 in currently supported extended operations. If no operation is
393 specified, the timeout val affects all supported operations.
394 Note: if the timelimit is exceeded, the operation is cancelled
396 (according to the cancel directive); the protocol does not
397 provide any means to rollback operations, so the client will not
398 be notified about the result of the operation, which may
399 eventually succeeded or not. In case the timeout is exceeded
400 during a bind operation, the connection is destroyed, according
401 to RFC4511.
402 Note: in some cases, this backend may issue binds prior to other
404 operations (e.g. to bind anonymously or with some prescribed
405 identity according to the idassert-bind directive). In this
406 case, the timeout of the operation that resulted in the bind is
407 used.
408 tls {none|[try-]start|[try-]propagate|ldaps} [starttls=no]
411 [tls_cert=<file>] [tls_key=<file>] [tls_cacert=<file>]
412 [tls_cacertdir=<path>] [tls_reqcert=never|allow|try|demand]
413 [tls_cipher_suite=<ciphers>] [tls_crlcheck=none|peer|all]
414 Specify TLS settings for regular connections.
415 The first parameter only applies to ldap:// connections and so
417 at the moment, none and ldaps are equivalent.
418 With propagate, the proxy issues StartTLS operation only if the
420 original connection has a TLS layer set up. The try- prefix
421 instructs the proxy to continue operations if the StartTLS
422 operation failed; its use is not recommended.
423 The TLS settings default to the same as the main slapd TLS
425 settings, except for tls_reqcert which defaults to "demand" and
426 starttls which is overshadowed by the first keyword and thus
427 ignored.
428 use-temporary-conn {NO|yes}
431 when set to yes, create a temporary connection whenever
432 competing with other threads for a shared one; otherwise, wait
433 until the shared connection is available.
434
437 The LDAP backend has been heavily reworked between releases 2.2 and
438 2.3, and subsequently between 2.3 and 2.4. As a side-effect, some of
439 the traditional directives have been deprecated and should be no longer
440 used, as they might disappear in future releases.
441 acl-authcDN <administrative DN for access control purposes>
444 Formerly known as the binddn, it is the DN that is used to query
445 the target server for acl checking; it is supposed to have read
446 access on the target server to attributes used on the proxy for
447 acl checking. There is no risk of giving away such values; they
448 are only used to check permissions.
449 The acl-authcDN identity is by no means implicitly used by the
451 proxy when the client connects anonymously. The idassert-*
452 feature can be used (at own risk) for that purpose instead.
453 This directive is obsoleted by the binddn arg of acl-bind when
455 bindmethod=simple, and will be dismissed in the future.
456 acl-passwd <password>
459 Formerly known as the bindpw, it is the password used with the
460 above acl-authcDN directive. This directive is obsoleted by the
461 credentials arg of acl-bind when bindmethod=simple, and will be
462 dismissed in the future.
463 idassert-authcDN <administrative DN for proxyAuthz purposes>
466 DN which is used to propagate the client's identity to the
467 target by means of the proxyAuthz control when the client does
468 not belong to the DIT fragment that is being proxied by back-
469 ldap. This directive is obsoleted by the binddn arg of
470 idassert-bind when bindmethod=simple, and will be dismissed in
471 the future.
472 idassert-passwd <password>
475 Password used with the idassert-authcDN above. This directive
476 is obsoleted by the crendentials arg of idassert-bind when
477 bindmethod=simple, and will be dismissed in the future.
478 idassert-mode <mode> [<flags>]
481 defines what type of identity assertion is used. This directive
482 is obsoleted by the mode arg of idassert-bind, and will be
483 dismissed in the future.
484 idassert-method <method> [<saslargs>]
487 This directive is obsoleted by the bindmethod arg of
488 idassert-bind, and will be dismissed in the future.
489 port <port>
492 this directive is no longer supported. Use the uri directive as
493 described above.
494 server <hostname[:port]>
497 this directive is no longer supported. Use the uri directive as
498 described above.
499 suffixmassage, map, rewrite*
502 These directives are no longer supported by back-ldap; their
503 functionality is now delegated to the rwm overlay. Essentially,
504 add a statement
505 overlay rwm
507 first, and prefix all rewrite/map statements with rwm- to obtain
509 the original behavior. See slapo-rwm(5) for details.
510
513 The ldap backend does not honor all ACL semantics as described in
514 slapd.access(5). In general, access checking is delegated to the
515 remote server(s). Only read (=r) access to the entry pseudo-attribute
516 and to the other attribute values of the entries returned by the search
517 operation is honored, which is performed by the frontend.
518
521 The LDAP backend provides basic proxying functionalities to many
522 overlays. The chain overlay, described in slapo-chain(5), and the
523 translucent overlay, described in slapo-translucent(5), deserve a
524 special mention.
525 Conversely, there are many overlays that are best used in conjunction
527 with the LDAP backend. The proxycache overlay allows caching of LDAP
528 search requests (queries) in a local database. See slapo-pcache(5) for
529 details. The rwm overlay provides DN rewrite and attribute/objectClass
530 mapping capabilities to the underlying database. See slapo-rwm(5) for
531 details.
532
535 /etc/openldap/slapd.conf
536 default slapd configuration file
537
539 slapd.conf(5), slapd-config(5), slapd-meta(5), slapo-chain(5),
540 slapo-pcache(5), slapo-rwm(5), slapo-translucent(5), slapd(8), ldap(3).
541
543 Howard Chu, with enhancements by Pierangelo Masarati
544OpenLDAP 2.4.50 2020/04/28 SLAPD-LDAP(5)