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, the slapd(8) threads pa‐
44 rameter may need some tuning. In those cases, one may consider using
45 slapd-relay(5) instead, which performs the relayed operation internally
46 and thus reuses the same connection.
47
50 These slapd.conf options apply to the LDAP backend database. That is,
51 they must follow a "database ldap" line and come before any subsequent
52 "backend" or "database" lines. Other database options are described in
53 the slapd.conf(5) manual page.
54 Note: In early versions of back-ldap it was recommended to always set
57 lastmod off
59 for ldap and meta databases. This was required because operational at‐
61 tributes related to entry creation and modification should not be prox‐
62 ied, as they could be mistakenly written to the target server(s), gen‐
63 erating an error. The current implementation automatically sets last‐
64 mod to off, so its use is redundant and should be omitted.
65 uri <ldapurl>
68 LDAP server to use. Multiple URIs can be set in a single lda‐
69 purl argument, resulting in the underlying library automatically
70 calling the first server of the list that responds, e.g.
71 uri "ldap://host/ ldap://backup-host/"
73 The URI list is space- or comma-separated. Whenever the server
75 that responds is not the first one in the list, the list is re‐
76 arranged and the responsive server is moved to the head, so that
77 it will be first contacted the next time a connection needs to
78 be created.
79 acl-bind bindmethod=simple|sasl [binddn=<simple DN>]
81 [credentials=<simple password>] [saslmech=<SASL mech>]
82 [secprops=<properties>] [realm=<realm>] [authcId=<authentication
83 ID>] [authzId=<authorization ID>] [starttls=no|yes|critical]
84 [tls_cert=<file>] [tls_key=<file>] [tls_cacert=<file>]
85 [tls_cacertdir=<path>] [tls_reqcert=never|allow|try|demand]
86 [tls_reqsan=never|allow|try|demand] [tls_cipher_suite=<ciphers>]
87 [tls_ecname=<names>] [tls_protocol_min=<major>[.<minor>]]
88 [tls_crlcheck=none|peer|all]
89 Allows one to define the parameters of the authentication method
90 that is internally used by the proxy to collect info related to
91 access control, and whenever an operation occurs with the
92 identity of the rootdn of the LDAP proxy database. The identity
93 defined by this directive, according to the properties
94 associated to the authentication method, is supposed to have
95 read access on the target server to attributes used on the proxy
96 for ACL checking.
97 There is no risk of giving away such values; they are only used
99 to check permissions. The default is to use simple bind, with
100 empty binddn and credentials, which means that the related
101 operations will be performed anonymously. If not set, and if
102 idassert-bind is defined, this latter identity is used instead.
103 See idassert-bind for details.
104 The connection between the proxy database and the remote server
106 associated to this identity is cached regardless of the lifespan
107 of the client-proxy connection that first established it.
108 This identity is not implicitly used by the proxy when the
110 client connects anonymously. The idassert-bind feature,
111 instead, in some cases can be crafted to implement that
112 behavior, which is intrinsically unsafe and should be used with
113 extreme care.
114 The TLS settings default to the same as the main slapd TLS
116 settings, except for tls_reqcert which defaults to "demand", and
117 tls_reqsan which defaults to "allow".
118 cancel {ABANDON|ignore|exop[-discover]}
121 Defines how to handle operation cancellation. By default,
122 abandon is invoked, so the operation is abandoned immediately.
123 If set to ignore, no action is taken and any further response is
124 ignored; this may result in further response messages to be
125 queued for that connection, so it is recommended that long
126 lasting connections are timed out either by idle-timeout or
127 conn-ttl, so that resources eventually get released. If set to
128 exop, a cancel operation (RFC 3909) is issued, resulting in the
129 cancellation of the current operation; the cancel operation
130 waits for remote server response, so its use may not be
131 recommended. If set to exop-discover, support of the cancel
132 extended operation is detected by reading the remote server's
133 root DSE.
134 chase-referrals {YES|no}
137 enable/disable automatic referral chasing, which is delegated to
138 the underlying libldap, with rebinding eventually performed if
139 the rebind-as-user directive is used. The default is to chase
140 referrals.
141 conn-pool-max <int>
144 This directive defines the maximum size of the privileged
145 connections pool.
146 conn-ttl <time>
149 This directive causes a cached connection to be dropped after a
150 given ttl, regardless of being idle or not. If a client
151 connection outlives the remote connection, the client will
152 receive LDAP_UNAVAILABLE when it executes the next operation.
153 idassert-authzFrom <authz-regexp>
157 if defined, selects what local identities are authorized to
158 exploit the identity assertion feature. The string <authz-
159 regexp> mostly follows the rules defined for the authzFrom
160 attribute. See slapd.conf(5), section related to authz-policy,
161 for details on the syntax of this field. This parameter differs
162 from the documented behavior in relation to the meaning of *,
163 which in this case allows anonymous rather than denies.
164 idassert-bind bindmethod=none|simple|sasl [binddn=<simple DN>]
167 [credentials=<simple password>] [saslmech=<SASL mech>]
168 [secprops=<properties>] [realm=<realm>] [authcId=<authentication
169 ID>] [authzId=<authorization ID>] [authz={native|proxyauthz}]
170 [mode=<mode>] [flags=<flags>] [starttls=no|yes|critical]
171 [tls_cert=<file>] [tls_key=<file>] [tls_cacert=<file>]
172 [tls_cacertdir=<path>] [tls_reqcert=never|allow|try|demand]
173 [tls_reqsan=never|allow|try|demand] [tls_cipher_suite=<ciphers>]
174 [tls_ecname=<names>] [tls_protocol_min=<version>]
175 [tls_crlcheck=none|peer|all]
176 Allows one to define the parameters of the authentication method
177 that is internally used by the proxy to authorize connections
178 that are authenticated by other databases. Direct binds are
179 always proxied without any idassert handling.
180 The identity defined by this directive, according to the
182 properties associated to the authentication method, is supposed
183 to have auth access on the target server to attributes used on
184 the proxy for authentication and authorization, and to be
185 allowed to authorize the users. This requires to have
186 proxyAuthz privileges on a wide set of DNs, e.g.
187 authzTo=dn.subtree:"", and the remote server to have
188 authz-policy set to to or both. See slapd.conf(5) for details
189 on these statements and for remarks and drawbacks about their
190 usage. The supported bindmethods are
191 none|simple|sasl
193 where none is the default, i.e. no identity assertion is
195 performed.
196 The authz parameter is used to instruct the SASL bind to exploit
198 native SASL authorization, if available; since connections are
199 cached, this should only be used when authorizing with a fixed
200 identity (e.g. by means of the authzDN or authzID parameters).
201 Otherwise, the default proxyauthz is used, i.e. the proxyAuthz
202 control (Proxied Authorization, RFC 4370) is added to all
203 operations.
204 The supported modes are:
206 <mode> := {legacy|anonymous|none|self}
208 If <mode> is not present, and authzId is given, the proxy always
210 authorizes that identity. <authorization ID> can be
211 u:<user>
213 [dn:]<DN>
215 The former is supposed to be expanded by the remote server
217 according to the authz rules; see slapd.conf(5) for details. In
218 the latter case, whether or not the dn: prefix is present, the
219 string must pass DN validation and normalization.
220 The default mode is legacy, which implies that the proxy will
222 either perform a simple bind as the authcDN or a SASL bind as
223 the authcID and assert the client's identity when it is not
224 anonymous. The other modes imply that the proxy will always
225 either perform a simple bind as the authcDN or a SASL bind as
226 the authcID, unless restricted by idassert-authzFrom rules (see
227 below), in which case the operation will fail; eventually, it
228 will assert some other identity according to <mode>. Other
229 identity assertion modes are anonymous and self, which
230 respectively mean that the empty or the client's identity will
231 be asserted; none, which means that no proxyAuthz control will
232 be used, so the authcDN or the authcID identity will be
233 asserted. For all modes that require the use of the proxyAuthz
234 control, on the remote server the proxy identity must have
235 appropriate authzTo permissions, or the asserted identities must
236 have appropriate authzFrom permissions. Note, however, that the
237 ID assertion feature is mostly useful when the asserted
238 identities do not exist on the remote server.
239 Flags can be
241 override,[non-]prescriptive,proxy-authz-[non-]critical,dn-{authzid|whoami}
243 When the override flag is used, identity assertion takes place
245 even when the database is authorizing for the identity of the
246 client, i.e. after binding with the provided identity, and thus
247 authenticating it, the proxy performs the identity assertion
248 using the configured identity and authentication method.
249 When the prescriptive flag is used (the default), operations
251 fail with inappropriateAuthentication for those identities whose
252 assertion is not allowed by the idassert-authzFrom patterns. If
253 the non-prescriptive flag is used, operations are performed
254 anonymously for those identities whose assertion is not allowed
255 by the idassert-authzFrom patterns.
256 When the proxy-authz-non-critical flag is used (the default),
258 the proxyAuthz control is not marked as critical, in violation
259 of RFC 4370. Use of proxy-authz-critical is recommended.
260 When the dn-authzid flag is used, RFC 3829 LDAP Authorization
262 Identity Controls is used to retrieve the identity associated to
263 the SASL identity; when the dn-whoami flag is used, RFC 4532
264 LDAP Who am I? Operation is performed after the bind for the
265 same purpose.
266 The TLS settings default to the same as the main slapd TLS
268 settings, except for tls_reqcert which defaults to "demand", and
269 tls_reqsan which defaults to "allow".
270 The identity associated to this directive is also used for
272 privileged operations whenever idassert-bind is defined and
273 acl-bind is not. See acl-bind for details.
274 idassert-passthru <authz-regexp>
277 if defined, selects what local identities bypass the
278 identity assertion feature. Those identities need to be
279 known by the remote host. The string <authz-regexp>
280 follows the rules defined for the authzFrom attribute.
281 See slapd.conf(5), section related to authz-policy, for
282 details on the syntax of this field.
283 idle-timeout <time>
286 This directive causes a cached connection to be dropped
287 after it has been idle for the specified time. If a
288 client connection outlives the remote connection, the
289 client will receive LDAP_UNAVAILABLE when it executes the
290 next operation.
291 keepalive <idle>:<probes>:<interval>
294 The keepalive parameter sets the values of idle, probes,
295 and interval used to check whether a socket is alive;
296 idle is the number of seconds a connection needs to
297 remain idle before TCP starts sending keepalive probes;
298 probes is the maximum number of keepalive probes TCP
299 should send before dropping the connection; interval is
300 interval in seconds between individual keepalive probes.
301 Only some systems support the customization of these
302 values; the keepalive parameter is ignored otherwise, and
303 system-wide settings are used.
304 tcp-user-timeout <milliseconds>
307 If non-zero, corresponds to the TCP_USER_TIMEOUT set on
308 the target connections, overriding the operating system
309 setting. Only some systems support the customization of
310 this parameter, it is ignored otherwise and system-wide
311 settings are used.
312 network-timeout <time>
315 Sets the network timeout value after which
316 poll(2)/select(2) following a connect(2) returns in case
317 of no activity. The value is in seconds, and it can be
318 specified as for idle-timeout.
319 norefs <NO|yes>
322 If yes, do not return search reference responses. By
323 default, they are returned unless request is LDAPv2.
324 omit-unknown-schema <NO|yes>
327 If yes, do not return objectClasses or attributes that
328 are not known to the local server. The default is to
329 return all schema elements.
330 noundeffilter <NO|yes>
333 If yes, return success instead of searching if a filter
334 is undefined or contains undefined portions. By default,
335 the search is propagated after replacing undefined
336 portions with (!(objectClass=*)), which corresponds to
337 the empty result set.
338 onerr {CONTINUE|stop}
341 This directive allows one to select the behavior in case
342 an error is returned by the remote server during a
343 search. The default, continue, consists in returning
344 success. If the value is set to stop, the error is
345 returned to the client.
346 protocol-version {0,2,3}
349 This directive indicates what protocol version must be
350 used to contact the remote server. If set to 0 (the
351 default), the proxy uses the same protocol version used
352 by the client, otherwise the requested protocol is used.
353 The proxy returns unwillingToPerform if an operation that
354 is incompatible with the requested protocol is attempted.
355 proxy-whoami {NO|yes}
358 Turns on proxying of the WhoAmI extended operation. If
359 this option is given, back-ldap will replace slapd's
360 original WhoAmI routine with its own. On slapd sessions
361 that were authenticated by back-ldap, the WhoAmI request
362 will be forwarded to the remote LDAP server. Other
363 sessions will be handled by the local slapd, as before.
364 This option is mainly useful in conjunction with Proxy
365 Authorization.
366 quarantine <interval>,<num>[;<interval>,<num>[...]]
369 Turns on quarantine of URIs that returned
370 LDAP_UNAVAILABLE, so that an attempt to reconnect only
371 occurs at given intervals instead of any time a client
372 requests an operation. The pattern is: retry only after
373 at least interval seconds elapsed since last attempt, for
374 exactly num times; then use the next pattern. If num for
375 the last pattern is "+", it retries forever; otherwise,
376 no more retries occur. The process can be restarted by
377 resetting the olcDbQuarantine attribute of the database
378 entry in the configuration backend.
379 rebind-as-user {NO|yes}
382 If this option is given, the client's bind credentials
383 are remembered for rebinds, when trying to re-establish a
384 broken connection, or when chasing a referral, if
385 chase-referrals is set to yes. Note, however, that
386 connection is not re-established automatically after it
387 was dropped due to idle-timeout or conn-ttl .
388 session-tracking-request {NO|yes}
391 Adds session tracking control for all requests. The
392 client's IP and hostname, and the identity associated to
393 each request, if known, are sent to the remote server for
394 informational purposes. This directive is incompatible
395 with setting protocol-version to 2.
396 single-conn {NO|yes}
399 Discards current cached connection when the client
400 rebinds.
401 t-f-support {NO|yes|discover}
404 enable if the remote server supports absolute filters
405 (see RFC 4526 for details). If set to discover, support
406 is detected by reading the remote server's root DSE.
407 timeout [<op>=]<val> [...]
410 This directive allows one to set per-operation timeouts.
411 Operations can be
412 <op> ::= bind, add, delete, modrdn, modify, compare,
414 search
415 The overall duration of the search operation is
417 controlled either by the timelimit parameter or by
418 server-side enforced time limits (see timelimit and
419 limits in slapd.conf(5) for details). This timeout
420 parameter controls how long the target can be
421 irresponsive before the operation is aborted. Timeout is
422 meaningless for the remaining operations, unbind and
423 abandon, which do not imply any response, while it is not
424 yet implemented in currently supported extended
425 operations. If no operation is specified, the timeout
426 val affects all supported operations.
427 Note: if the timelimit is exceeded, the operation is
429 cancelled (according to the cancel directive); the
430 protocol does not provide any means to rollback
431 operations, so the client will not be notified about the
432 result of the operation, which may eventually succeeded
433 or not. In case the timeout is exceeded during a bind
434 operation, the connection is destroyed, according to
435 RFC4511.
436 Note: in some cases, this backend may issue binds prior
438 to other operations (e.g. to bind anonymously or with
439 some prescribed identity according to the idassert-bind
440 directive). In this case, the timeout of the operation
441 that resulted in the bind is used.
442 tls {none|[try-]start|[try-]propagate|ldaps} [starttls=no]
445 [tls_cert=<file>] [tls_key=<file>] [tls_cacert=<file>]
446 [tls_cacertdir=<path>]
447 [tls_reqcert=never|allow|try|demand]
448 [tls_reqsan=never|allow|try|demand]
449 [tls_cipher_suite=<ciphers>] [tls_ecname=<names>]
450 [tls_crlcheck=none|peer|all]
451 Specify TLS settings for regular connections.
452 If the first parameter is not "none" then this configures
454 the TLS settings to be used for regular connections. The
455 StartTLS extended operation will be used when
456 establishing the connection unless the URI directive
457 protocol scheme is ldaps://. In that case this keyword
458 may only be set to "ldaps" and the StartTLS operation
459 will not be used.
460 With propagate, the proxy issues the StartTLS operation
462 only if the original connection has a TLS layer set up.
463 The try- prefix instructs the proxy to continue
464 operations if the StartTLS operation failed; its use is
465 not recommended.
466 The TLS settings default to the same as the main slapd
468 TLS settings, except for tls_reqcert which defaults to
469 "demand", tls_reqsan which defaults to "allow", and
470 starttls which is overshadowed by the first keyword and
471 thus ignored.
472 use-temporary-conn {NO|yes}
475 when set to yes, create a temporary connection whenever
476 competing with other threads for a shared one; otherwise,
477 wait until the shared connection is available.
478
481 The ldap backend does not honor all ACL semantics as described in
482 slapd.access(5). In general, access checking is delegated to the
483 remote server(s). Only read (=r) access to the entry pseudo-attribute
484 and to the other attribute values of the entries returned by the search
485 operation is honored, which is performed by the frontend.
486
489 The LDAP backend provides basic proxying functionalities to many
490 overlays. The chain overlay, described in slapo-chain(5), and the
491 translucent overlay, described in slapo-translucent(5), deserve a
492 special mention.
493 Conversely, there are many overlays that are best used in conjunction
495 with the LDAP backend. The proxycache overlay allows caching of LDAP
496 search requests (queries) in a local database. See slapo-pcache(5) for
497 details. The rwm overlay provides DN rewrite and attribute/objectClass
498 mapping capabilities to the underlying database. See slapo-rwm(5) for
499 details.
500
503 /etc/openldap/slapd.conf
504 default slapd configuration file
505
507 slapd.conf(5), slapd-config(5), slapd-meta(5), slapo-chain(5),
508 slapo-pcache(5), slapo-rwm(5), slapo-translucent(5), slapd(8), ldap(3).
509
511 Howard Chu, with enhancements by Pierangelo Masarati
512OpenLDAP 2.6.2 2022/05/04 SLAPD-LDAP(5)