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
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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> follows the rules defined for the authzFrom attribute.
153 See slapd.conf(5), section related to authz-policy, for details
154 on the syntax of this field.
155 idassert-bind bindmethod=none|simple|sasl [binddn=<simple DN>]
158 [credentials=<simple password>] [saslmech=<SASL mech>]
159 [secprops=<properties>] [realm=<realm>] [authcId=<authentication
160 ID>] [authzId=<authorization ID>] [authz={native|proxyauthz}]
161 [mode=<mode>] [flags=<flags>] [starttls=no|yes|critical]
162 [tls_cert=<file>] [tls_key=<file>] [tls_cacert=<file>]
163 [tls_cacertdir=<path>] [tls_reqcert=never|allow|try|demand]
164 [tls_cipher_suite=<ciphers>] [tls_protocol_min=<version>]
165 [tls_crlcheck=none|peer|all]
166 Allows one to define the parameters of the authentication method
167 that is internally used by the proxy to authorize connections
168 that are authenticated by other databases. Direct binds are
169 always proxied without any idassert handling.
170 The identity defined by this directive, according to the
172 properties associated to the authentication method, is supposed
173 to have auth access on the target server to attributes used on
174 the proxy for authentication and authorization, and to be
175 allowed to authorize the users. This requires to have
176 proxyAuthz privileges on a wide set of DNs, e.g.
177 authzTo=dn.subtree:"", and the remote server to have
178 authz-policy set to to or both. See slapd.conf(5) for details
179 on these statements and for remarks and drawbacks about their
180 usage. The supported bindmethods are
181 none|simple|sasl
183 where none is the default, i.e. no identity assertion is
185 performed.
186 The authz parameter is used to instruct the SASL bind to exploit
188 native SASL authorization, if available; since connections are
189 cached, this should only be used when authorizing with a fixed
190 identity (e.g. by means of the authzDN or authzID parameters).
191 Otherwise, the default proxyauthz is used, i.e. the proxyAuthz
192 control (Proxied Authorization, RFC 4370) is added to all
193 operations.
194 The supported modes are:
196 <mode> := {legacy|anonymous|none|self}
198 If <mode> is not present, and authzId is given, the proxy always
200 authorizes that identity. <authorization ID> can be
201 u:<user>
203 [dn:]<DN>
205 The former is supposed to be expanded by the remote server
207 according to the authz rules; see slapd.conf(5) for details. In
208 the latter case, whether or not the dn: prefix is present, the
209 string must pass DN validation and normalization.
210 The default mode is legacy, which implies that the proxy will
212 either perform a simple bind as the authcDN or a SASL bind as
213 the authcID and assert the client's identity when it is not
214 anonymous. The other modes imply that the proxy will always
215 either perform a simple bind as the authcDN or a SASL bind as
216 the authcID, unless restricted by idassert-authzFrom rules (see
217 below), in which case the operation will fail; eventually, it
218 will assert some other identity according to <mode>. Other
219 identity assertion modes are anonymous and self, which
220 respectively mean that the empty or the client's identity will
221 be asserted; none, which means that no proxyAuthz control will
222 be used, so the authcDN or the authcID identity will be
223 asserted. For all modes that require the use of the proxyAuthz
224 control, on the remote server the proxy identity must have
225 appropriate authzTo permissions, or the asserted identities must
226 have appropriate authzFrom permissions. Note, however, that the
227 ID assertion feature is mostly useful when the asserted
228 identities do not exist on the remote server.
229 Flags can be
231 override,[non-]prescriptive,proxy-authz-[non-]critical
233 When the override flag is used, identity assertion takes place
235 even when the database is authorizing for the identity of the
236 client, i.e. after binding with the provided identity, and thus
237 authenticating it, the proxy performs the identity assertion
238 using the configured identity and authentication method.
239 When the prescriptive flag is used (the default), operations
241 fail with inappropriateAuthentication for those identities whose
242 assertion is not allowed by the idassert-authzFrom patterns. If
243 the non-prescriptive flag is used, operations are performed
244 anonymously for those identities whose assertion is not allowed
245 by the idassert-authzFrom patterns.
246 When the proxy-authz-non-critical flag is used (the default),
248 the proxyAuthz control is not marked as critical, in violation
249 of RFC 4370. Use of proxy-authz-critical is recommended.
250 The TLS settings default to the same as the main slapd TLS
252 settings, except for tls_reqcert which defaults to "demand".
253 The identity associated to this directive is also used for
255 privileged operations whenever idassert-bind is defined and
256 acl-bind is not. See acl-bind for details.
257 This directive obsoletes idassert-authcDN, idassert-passwd,
259 idassert-mode, and idassert-method.
260 idassert-passthru <authz-regexp>
263 if defined, selects what local identities bypass the identity
264 assertion feature. Those identities need to be known by the
265 remote host. The string <authz-regexp> follows the rules
266 defined for the authzFrom attribute. See slapd.conf(5), section
267 related to authz-policy, for details on the syntax of this
268 field.
269 idle-timeout <time>
273 This directive causes a cached connection to be dropped an
274 recreated after it has been idle for the specified time.
275 keepalive <idle>:<probes>:<interval>
278 The keepalive parameter sets the values of idle, probes, and
279 interval used to check whether a socket is alive; idle is the
280 number of seconds a connection needs to remain idle before TCP
281 starts sending keepalive probes; probes is the maximum number of
282 keepalive probes TCP should send before dropping the connection;
283 interval is interval in seconds between individual keepalive
284 probes. Only some systems support the customization of these
285 values; the keepalive parameter is ignored otherwise, and
286 system-wide settings are used.
287 network-timeout <time>
290 Sets the network timeout value after which poll(2)/select(2)
291 following a connect(2) returns in case of no activity. The
292 value is in seconds, and it can be specified as for
293 idle-timeout.
294 norefs <NO|yes>
297 If yes, do not return search reference responses. By default,
298 they are returned unless request is LDAPv2.
299 omit-unknown-schema <NO|yes>
302 If yes, do not return objectClasses or attributes that are not
303 known to the local server. The default is to return all schema
304 elements.
305 noundeffilter <NO|yes>
308 If yes, return success instead of searching if a filter is
309 undefined or contains undefined portions. By default, the
310 search is propagated after replacing undefined portions with
311 (!(objectClass=*)), which corresponds to the empty result set.
312 onerr {CONTINUE|stop}
315 This directive allows one to select the behavior in case an
316 error is returned by the remote server during a search. The
317 default, continue, consists in returning success. If the value
318 is set to stop, the error is returned to the client.
319 protocol-version {0,2,3}
322 This directive indicates what protocol version must be used to
323 contact the remote server. If set to 0 (the default), the proxy
324 uses the same protocol version used by the client, otherwise the
325 requested protocol is used. The proxy returns
326 unwillingToPerform if an operation that is incompatible with the
327 requested protocol is attempted.
328 proxy-whoami {NO|yes}
331 Turns on proxying of the WhoAmI extended operation. If this
332 option is given, back-ldap will replace slapd's original WhoAmI
333 routine with its own. On slapd sessions that were authenticated
334 by back-ldap, the WhoAmI request will be forwarded to the remote
335 LDAP server. Other sessions will be handled by the local slapd,
336 as before. This option is mainly useful in conjunction with
337 Proxy Authorization.
338 quarantine <interval>,<num>[;<interval>,<num>[...]]
341 Turns on quarantine of URIs that returned LDAP_UNAVAILABLE, so
342 that an attempt to reconnect only occurs at given intervals
343 instead of any time a client requests an operation. The pattern
344 is: retry only after at least interval seconds elapsed since
345 last attempt, for exactly num times; then use the next pattern.
346 If num for the last pattern is "+", it retries forever;
347 otherwise, no more retries occur. The process can be restarted
348 by resetting the olcDbQuarantine attribute of the database entry
349 in the configuration backend.
350 rebind-as-user {NO|yes}
353 If this option is given, the client's bind credentials are
354 remembered for rebinds, when trying to re-establish a broken
355 connection, or when chasing a referral, if chase-referrals is
356 set to yes.
357 session-tracking-request {NO|yes}
360 Adds session tracking control for all requests. The client's IP
361 and hostname, and the identity associated to each request, if
362 known, are sent to the remote server for informational purposes.
363 This directive is incompatible with setting protocol-version to
364 2.
365 single-conn {NO|yes}
368 Discards current cached connection when the client rebinds.
369 t-f-support {NO|yes|discover}
372 enable if the remote server supports absolute filters (see RFC
373 4526 for details). If set to discover, support is detected by
374 reading the remote server's root DSE.
375 timeout [<op>=]<val> [...]
378 This directive allows one to set per-operation timeouts.
379 Operations can be
380 <op> ::= bind, add, delete, modrdn, modify, compare, search
382 The overall duration of the search operation is controlled
384 either by the timelimit parameter or by server-side enforced
385 time limits (see timelimit and limits in slapd.conf(5) for
386 details). This timeout parameter controls how long the target
387 can be irresponsive before the operation is aborted. Timeout is
388 meaningless for the remaining operations, unbind and abandon,
389 which do not imply any response, while it is not yet implemented
390 in currently supported extended operations. If no operation is
391 specified, the timeout val affects all supported operations.
392 Note: if the timelimit is exceeded, the operation is cancelled
394 (according to the cancel directive); the protocol does not
395 provide any means to rollback operations, so the client will not
396 be notified about the result of the operation, which may
397 eventually succeeded or not. In case the timeout is exceeded
398 during a bind operation, the connection is destroyed, according
399 to RFC4511.
400 Note: in some cases, this backend may issue binds prior to other
402 operations (e.g. to bind anonymously or with some prescribed
403 identity according to the idassert-bind directive). In this
404 case, the timeout of the operation that resulted in the bind is
405 used.
406 tls {[try-]start|[try-]propagate|ldaps} [tls_cert=<file>]
409 [tls_key=<file>] [tls_cacert=<file>] [tls_cacertdir=<path>]
410 [tls_reqcert=never|allow|try|demand]
411 [tls_cipher_suite=<ciphers>] [tls_crlcheck=none|peer|all]
412 Specify the use of TLS when a regular connection is initialized.
413 The StartTLS extended operation will be used unless the URI
414 directive protocol scheme is ldaps://. In that case this keyword
415 may only be set to "ldaps" and the StartTLS operation will not
416 be used. propagate issues the StartTLS operation only if the
417 original connection did. The try- prefix instructs the proxy to
418 continue operations if the StartTLS operation failed; its use is
419 not recommended.
420 The TLS settings default to the same as the main slapd TLS
422 settings, except for tls_reqcert which defaults to "demand".
423 use-temporary-conn {NO|yes}
426 when set to yes, create a temporary connection whenever
427 competing with other threads for a shared one; otherwise, wait
428 until the shared connection is available.
429
432 The LDAP backend has been heavily reworked between releases 2.2 and
433 2.3, and subsequently between 2.3 and 2.4. As a side-effect, some of
434 the traditional directives have been deprecated and should be no longer
435 used, as they might disappear in future releases.
436 acl-authcDN <administrative DN for access control purposes>
439 Formerly known as the binddn, it is the DN that is used to query
440 the target server for acl checking; it is supposed to have read
441 access on the target server to attributes used on the proxy for
442 acl checking. There is no risk of giving away such values; they
443 are only used to check permissions.
444 The acl-authcDN identity is by no means implicitly used by the
446 proxy when the client connects anonymously. The idassert-*
447 feature can be used (at own risk) for that purpose instead.
448 This directive is obsoleted by the binddn arg of acl-bind when
450 bindmethod=simple, and will be dismissed in the future.
451 acl-passwd <password>
454 Formerly known as the bindpw, it is the password used with the
455 above acl-authcDN directive. This directive is obsoleted by the
456 credentials arg of acl-bind when bindmethod=simple, and will be
457 dismissed in the future.
458 idassert-authcDN <administrative DN for proxyAuthz purposes>
461 DN which is used to propagate the client's identity to the
462 target by means of the proxyAuthz control when the client does
463 not belong to the DIT fragment that is being proxied by back-
464 ldap. This directive is obsoleted by the binddn arg of
465 idassert-bind when bindmethod=simple, and will be dismissed in
466 the future.
467 idassert-passwd <password>
470 Password used with the idassert-authcDN above. This directive
471 is obsoleted by the crendentials arg of idassert-bind when
472 bindmethod=simple, and will be dismissed in the future.
473 idassert-mode <mode> [<flags>]
476 defines what type of identity assertion is used. This directive
477 is obsoleted by the mode arg of idassert-bind, and will be
478 dismissed in the future.
479 idassert-method <method> [<saslargs>]
482 This directive is obsoleted by the bindmethod arg of
483 idassert-bind, and will be dismissed in the future.
484 port <port>
487 this directive is no longer supported. Use the uri directive as
488 described above.
489 server <hostname[:port]>
492 this directive is no longer supported. Use the uri directive as
493 described above.
494 suffixmassage, map, rewrite*
497 These directives are no longer supported by back-ldap; their
498 functionality is now delegated to the rwm overlay. Essentially,
499 add a statement
500 overlay rwm
502 first, and prefix all rewrite/map statements with rwm- to obtain
504 the original behavior. See slapo-rwm(5) for details.
505
508 The ldap backend does not honor all ACL semantics as described in
509 slapd.access(5). In general, access checking is delegated to the
510 remote server(s). Only read (=r) access to the entry pseudo-attribute
511 and to the other attribute values of the entries returned by the search
512 operation is honored, which is performed by the frontend.
513
516 The LDAP backend provides basic proxying functionalities to many
517 overlays. The chain overlay, described in slapo-chain(5), and the
518 translucent overlay, described in slapo-translucent(5), deserve a
519 special mention.
520 Conversely, there are many overlays that are best used in conjunction
522 with the LDAP backend. The proxycache overlay allows caching of LDAP
523 search requests (queries) in a local database. See slapo-pcache(5) for
524 details. The rwm overlay provides DN rewrite and attribute/objectClass
525 mapping capabilities to the underlying database. See slapo-rwm(5) for
526 details.
527
530 /etc/openldap/slapd.conf
531 default slapd configuration file
532
534 slapd.conf(5), slapd-config(5), slapd-meta(5), slapo-chain(5),
535 slapo-pcache(5), slapo-rwm(5), slapo-translucent(5), slapd(8), ldap(3).
536
538 Howard Chu, with enhancements by Pierangelo Masarati
539OpenLDAP 2.4.47 2018/12/19 SLAPD-LDAP(5)