1 .TH SLAPD-META 5 "RELEASEDATE" "OpenLDAP LDVERSION"
2 .\" Copyright 1998-2008 The OpenLDAP Foundation, All Rights Reserved.
3 .\" Copying restrictions apply. See the COPYRIGHT file.
4 .\" Copyright 2001, Pierangelo Masarati, All rights reserved. <ando@sys-net.it>
7 .\" Portions of this document should probably be moved to slapd-ldap(5)
8 .\" and maybe manual pages for librewrite.
11 slapd-meta \- metadirectory backend to slapd
19 performs basic LDAP proxying with respect to a set of remote LDAP
20 servers, called "targets".
21 The information contained in these servers can be presented as
22 belonging to a single Directory Information Tree (DIT).
24 A basic knowledge of the functionality of the
26 backend is recommended.
27 This backend has been designed as an enhancement of the ldap backend.
28 The two backends share many features (actually they also share
32 backend is intended to proxy operations directed to a single server, the
34 backend is mainly intended for proxying of multiple servers and possibly
35 naming context masquerading.
36 These features, although useful in many scenarios, may result in
37 excessive overhead for some applications, so its use should be
39 In the examples section, some typical scenarios will be discussed.
43 must contain schema information for the attributes and objectClasses
44 used in filters, request DN and request-related data in general.
45 It should also contain schema information for the data returned
46 by the proxied server.
47 It is the responsibility of the proxy administrator to keep the schema
48 of the proxy lined up with that of the proxied server.
51 Note: When looping back to the same instance of \fBslapd\fP(8),
52 each connection requires a new thread; as a consequence, \fBslapd\fP(8)
53 must be compiled with thread support, and the \fBthreads\fP parameter
54 may need some tuning; in those cases, unless the multiple target feature
55 is required, one may consider using \fBslapd-relay\fP(5) instead,
56 which performs the relayed operation internally and thus reuses
60 There are examples in various places in this document, as well as in the
61 slapd/back-meta/data/ directory in the OpenLDAP source tree.
65 options apply to the META backend database.
66 That is, they must follow a "database meta" line and come before any
67 subsequent "backend" or "database" lines.
68 Other database options are described in the
72 Note: In early versions of back-ldap and back-meta it was recommended to always set
85 This was required because operational attributes related to entry creation
86 and modification should not be proxied, as they could be mistakenly written
87 to the target server(s), generating an error.
88 The current implementation automatically sets lastmod to \fBoff\fP,
89 so its use is redundant and should be omitted.
91 .SH SPECIAL CONFIGURATION DIRECTIVES
92 Target configuration starts with the "uri" directive.
93 All the configuration directives that are not specific to targets
94 should be defined first for clarity, including those that are common
100 This directive causes a cached connection to be dropped an recreated
101 after a given ttl, regardless of being idle or not.
104 .B default-target none
105 This directive forces the backend to reject all those operations
106 that must resolve to a single target in case none or multiple
107 targets are selected.
108 They include: add, delete, modify, modrdn; compare is not included, as
109 well as bind since, as they don't alter entries, in case of multiple
110 matches an attempt is made to perform the operation on any candidate
111 target, with the constraint that at most one must succeed.
112 This directive can also be used when processing targets to mark a
113 specific target as default.
116 .B dncache-ttl {DISABLED|forever|<ttl>}
117 This directive sets the time-to-live of the DN cache.
118 This caches the target that holds a given DN to speed up target
119 selection in case multiple targets would result from an uncached
120 search; forever means cache never expires; disabled means no DN
121 caching; otherwise a valid ( > 0 ) ttl is required, in the format
127 .B onerr {CONTINUE|report|stop}
128 This directive allows to select the behavior in case an error is returned
129 by one target during a search.
130 The default, \fBcontinue\fP, consists in continuing the operation,
131 trying to return as much data as possible.
132 If the value is set to \fBstop\fP, the search is terminated as soon
133 as an error is returned by one target, and the error is immediately
134 propagated to the client.
135 If the value is set to \fBreport\fP, the search is continuated to the end
136 but, in case at least one target returned an error code, the first
137 non-success error code is returned.
143 do not return search reference responses.
144 By default, they are returned unless request is LDAPv2.
145 If set before any target specification, it affects all targets, unless
146 overridden by any per-target directive.
149 .B noundeffilter <NO|yes>
152 return success instead of searching if a filter is undefined or contains
154 By default, the search is propagated after replacing undefined portions
156 .BR (!(objectClass=*)) ,
157 which corresponds to the empty result set.
158 If set before any target specification, it affects all targets, unless
159 overridden by any per-target directive.
162 .B protocol\-version {0,2,3}
163 This directive indicates what protocol version must be used to contact
165 If set to 0 (the default), the proxy uses the same protocol version
166 used by the client, otherwise the requested protocol is used.
167 The proxy returns \fIunwillingToPerform\fP if an operation that is
168 incompatible with the requested protocol is attempted.
169 If set before any target specification, it affects all targets, unless
170 overridden by any per-target directive.
173 .B pseudoroot-bind-defer {YES|no}
174 This directive, when set to
176 causes the authentication to the remote servers with the pseudo-root
177 identity to be deferred until actually needed by subsequent operations.
178 Otherwise, all binds as the rootdn are propagated to the targets.
181 .B quarantine <interval>,<num>[;<interval>,<num>[...]]
182 Turns on quarantine of URIs that returned
183 .IR LDAP_UNAVAILABLE ,
184 so that an attempt to reconnect only occurs at given intervals instead
185 of any time a client requests an operation.
186 The pattern is: retry only after at least
188 seconds elapsed since last attempt, for exactly
190 times; then use the next pattern.
193 for the last pattern is "\fB+\fP", it retries forever; otherwise,
194 no more retries occur.
195 This directive must appear before any target specification;
196 it affects all targets with the same pattern.
199 .B rebind-as-user {NO|yes}
200 If this option is given, the client's bind credentials are remembered
201 for rebinds, when trying to re-establish a broken connection,
202 or when chasing a referral, if
208 .B session\-tracking\-request {NO|yes}
209 Adds session tracking control for all requests.
210 The client's IP and hostname, and the identity associated to each request,
211 if known, are sent to the remote server for informational purposes.
212 This directive is incompatible with setting \fIprotocol\-version\fP to 2.
213 If set before any target specification, it affects all targets, unless
214 overridden by any per-target directive.
217 .B single\-conn {NO|yes}
218 Discards current cached connection when the client rebinds.
221 .B use-temporary-conn {NO|yes}
224 create a temporary connection whenever competing with other threads
225 for a shared one; otherwise, wait until the shared connection is available.
227 .SH TARGET SPECIFICATION
228 Target specification starts with a "uri" directive:
231 .B uri <protocol>://[<host>]/<naming context> [...]
232 The <protocol> part can be anything
233 .BR ldap_initialize (3)
234 accepts ({ldap|ldaps|ldapi} and variants); the <host> may be
235 omitted, defaulting to whatever is set in
237 The <naming context> part is \fImandatory\fP for the first URI,
238 but it \fImust be omitted\fP for subsequent ones, if any.
239 The naming context part must be within the naming context defined for the backend,
244 suffix "\fBdc=foo,dc=com\fP"
245 uri "ldap://x.foo.com/dc=x,\fBdc=foo,dc=com\fP"
250 The <naming context> part doesn't need to be unique across the targets;
251 it may also match one of the values of the "suffix" directive.
252 Multiple URIs may be defined in a single URI statement.
253 The additional URIs must be separate arguments and must not have any
254 <naming context> part. This causes the underlying library
255 to contact the first server of the list that responds.
256 For example, if \fIl1.foo.com\fP and \fIl2.foo.com\fP are shadows
257 of the same server, the directive
260 suffix "\fBdc=foo,dc=com\fP"
261 uri "ldap://l1.foo.com/\fBdc=foo,dc=com\fP" "ldap://l2.foo.com/"
266 causes \fIl2.foo.com\fP to be contacted whenever \fIl1.foo.com\fP
268 In that case, the URI list is internally rearranged, by moving unavailable
269 URIs to the end, so that further connection attempts occur with respect to
270 the last URI that succeeded.
274 .B acl-authcDN "<administrative DN for access control purposes>"
275 DN which is used to query the target server for acl checking,
276 as in the LDAP backend; it is supposed to have read access
277 on the target server to attributes used on the proxy for acl checking.
278 There is no risk of giving away such values; they are only used to
280 .B The acl-authcDN identity is by no means implicitly used by the proxy
281 .B when the client connects anonymously.
284 .B acl-passwd <password>
285 Password used with the
291 .B bind-timeout <microseconds>
292 This directive defines the timeout, in microseconds, used when polling
293 for response after an asynchronous bind connection. The initial call
294 to ldap_result(3) is performed with a trade-off timeout of 100000 us;
295 if that results in a timeout exceeded, subsequent calls use the value
298 The default value is used also for subsequent calls if
301 If set before any target specification, it affects all targets, unless
302 overridden by any per-target directive.
305 .B chase-referrals {YES|no}
306 enable/disable automatic referral chasing, which is delegated to the
307 underlying libldap, with rebinding eventually performed if the
308 \fBrebind-as-user\fP directive is used. The default is to chase referrals.
309 If set before any target specification, it affects all targets, unless
310 overridden by any per-target directive.
313 .B default-target [<target>]
314 The "default-target" directive can also be used during target specification.
315 With no arguments it marks the current target as the default.
316 The optional number marks target <target> as the default one, starting
318 Target <target> must be defined.
321 .B idassert-authzFrom <authz-regexp>
322 if defined, selects what
324 identities are authorized to exploit the identity assertion feature.
327 follows the rules defined for the
334 for details on the syntax of this field.
339 .B bindmethod=none|simple|sasl [binddn=<simple DN>] [credentials=<simple password>]
340 .B [saslmech=<SASL mech>] [secprops=<properties>] [realm=<realm>]
341 .B [authcId=<authentication ID>] [authzId=<authorization ID>]
342 .B [authz={native|proxyauthz}] [mode=<mode>] [flags=<flags>]
345 .B [tls_cacert=<file>]
346 .B [tls_cacertdir=<path>]
347 .B [tls_reqcert=never|allow|try|demand]
348 .B [tls_ciphersuite=<ciphers>]
349 .B [tls_crlcheck=none|peer|all]
351 Allows to define the parameters of the authentication method that is
352 internally used by the proxy to authorize connections that are
353 authenticated by other databases.
354 The identity defined by this directive, according to the properties
355 associated to the authentication method, is supposed to have auth access
356 on the target server to attributes used on the proxy for authentication
357 and authorization, and to be allowed to authorize the users.
358 This requires to have
360 privileges on a wide set of DNs, e.g.
361 .BR authzTo=dn.subtree:"" ,
362 and the remote server to have
370 for details on these statements and for remarks and drawbacks about
372 The supported bindmethods are
374 \fBnone|simple|sasl\fP
378 is the default, i.e. no \fIidentity assertion\fP is performed.
380 The authz parameter is used to instruct the SASL bind to exploit
382 SASL authorization, if available; since connections are cached,
383 this should only be used when authorizing with a fixed identity
384 (e.g. by means of the
389 Otherwise, the default
391 is used, i.e. the proxyAuthz control (Proxied Authorization, RFC 4370)
392 is added to all operations.
394 The supported modes are:
396 \fB<mode> := {legacy|anonymous|none|self}\fP
402 is given, the proxy always authorizes that identity.
403 .B <authorization ID>
410 The former is supposed to be expanded by the remote server according
411 to the authz rules; see
414 In the latter case, whether or not the
416 prefix is present, the string must pass DN validation and normalization.
420 which implies that the proxy will either perform a simple bind as the
422 or a SASL bind as the
424 and assert the client's identity when it is not anonymous.
425 Direct binds are always proxied.
426 The other modes imply that the proxy will always either perform a simple bind
429 or a SASL bind as the
432 .BR idassert-authzFrom
433 rules (see below), in which case the operation will fail;
434 eventually, it will assert some other identity according to
436 Other identity assertion modes are
440 which respectively mean that the
447 which means that no proxyAuthz control will be used, so the
451 identity will be asserted.
452 For all modes that require the use of the
454 control, on the remote server the proxy identity must have appropriate
456 permissions, or the asserted identities must have appropriate
458 permissions. Note, however, that the ID assertion feature is mostly
459 useful when the asserted identities do not exist on the remote server.
463 \fBoverride,[non-]prescriptive\fP
467 flag is used, identity assertion takes place even when the database
468 is authorizing for the identity of the client, i.e. after binding
469 with the provided identity, and thus authenticating it, the proxy
470 performs the identity assertion using the configured identity and
471 authentication method.
475 flag is used (the default), operations fail with
476 \fIinappropriateAuthentication\fP
477 for those identities whose assertion is not allowed by the
478 .B idassert-authzFrom
482 flag is used, operations are performed anonymously for those identities
483 whose assertion is not allowed by the
484 .B idassert-authzFrom
487 The TLS settings default to the same as the main slapd TLS settings,
490 which defaults to "demand".
492 The identity associated to this directive is also used for privileged
493 operations whenever \fBidassert-bind\fP is defined and \fBacl-bind\fP
494 is not. See \fBacl-bind\fP for details.
498 .B idle-timeout <time>
499 This directive causes a cached connection to be dropped an recreated
500 after it has been idle for the specified time.
501 The value can be specified as
503 [<d>d][<h>h][<m>m][<s>[s]]
505 where <d>, <h>, <m> and <s> are respectively treated as days, hours,
507 If set before any target specification, it affects all targets, unless
508 overridden by any per-target directive.
511 .B map "{attribute|objectclass} [<local name>|*] {<foreign name>|*}"
512 This maps object classes and attributes as in the LDAP backend.
517 .B network-timeout <time>
518 Sets the network timeout value after which
519 .BR poll (2)/ select (2)
522 returns in case of no activity.
523 The value is in seconds, and it can be specified as for
525 If set before any target specification, it affects all targets, unless
526 overridden by any per-target directive.
529 .B nretries {forever|never|<nretries>}
530 This directive defines how many times a bind should be retried
531 in case of temporary failure in contacting a target. If defined
532 before any target specification, it applies to all targets (by default,
535 the global value can be overridden by redefinitions inside each target
539 .B pseudorootdn "<substitute DN in case of rootdn bind>"
540 This directive, if present, sets the DN that will be substituted to
541 the bind DN if a bind with the backend's "rootdn" succeeds.
542 The true "rootdn" of the target server ought not be used; an arbitrary
543 administrative DN should used instead.
546 .B pseudorootpw "<substitute password in case of rootdn bind>"
547 This directive sets the credential that will be used in case a bind
548 with the backend's "rootdn" succeeds, and the bind is propagated to
549 the target using the "pseudorootdn" DN.
551 Note: cleartext credentials must be supplied here; as a consequence,
552 using the pseudorootdn/pseudorootpw directives is inherently unsafe.
556 The rewrite options are described in the "REWRITING" section.
559 .B subtree-exclude "<DN>"
560 This directive instructs back-meta to ignore the current target
561 for operations whose requestDN is subordinate to
563 There may be multiple occurrences of the
565 directive for each of the targets.
568 .B suffixmassage "<virtual naming context>" "<real naming context>"
569 All the directives starting with "rewrite" refer to the rewrite engine
570 that has been added to slapd.
571 The "suffixmassage" directive was introduced in the LDAP backend to
572 allow suffix massaging while proxying.
573 It has been obsoleted by the rewriting tools.
574 However, both for backward compatibility and for ease of configuration
575 when simple suffix massage is required, it has been preserved.
576 It wraps the basic rewriting instructions that perform suffix
577 massaging. See the "REWRITING" section for a detailed list
578 of the rewrite rules it implies.
581 .B t-f-support {NO|yes|discover}
582 enable if the remote server supports absolute filters
583 (see \fIdraft-zeilenga-ldap-t-f\fP for details).
586 support is detected by reading the remote server's root DSE.
587 If set before any target specification, it affects all targets, unless
588 overridden by any per-target directive.
591 .B timeout [<op>=]<val> [...]
592 This directive allows to set per-operation timeouts.
595 \fB<op> ::= bind, add, delete, modrdn, modify, compare, search\fP
597 The overall duration of the \fBsearch\fP operation is controlled either
598 by the \fBtimelimit\fP parameter or by server-side enforced
599 time limits (see \fBtimelimit\fP and \fBlimits\fP in
602 This \fBtimeout\fP parameter controls how long the target can be
603 irresponsive before the operation is aborted.
604 Timeout is meaningless for the remaining operations,
605 \fBunbind\fP and \fBabandon\fP, which do not imply any response,
606 while it is not yet implemented in currently supported \fBextended\fP
608 If no operation is specified, the timeout \fBval\fP affects all
609 supported operations.
610 If specified before any target definition, it affects all targets
611 unless overridden by per-target directives.
613 Note: if the timeout is exceeded, the operation is cancelled
614 (according to the \fBcancel\fP directive);
615 the protocol does not provide any means to rollback operations,
616 so the client will not be notified about the result of the operation,
617 which may eventually succeeded or not.
618 In case the timeout is exceeded during a bind operation, the connection
619 is destroyed, according to RFC4511.
622 .B tls {[try-]start|[try-]propagate}
623 execute the StartTLS extended operation when the connection is initialized;
624 only works if the URI directive protocol scheme is not \fBldaps://\fP.
625 \fBpropagate\fP issues the StartTLS operation only if the original
627 The \fBtry-\fP prefix instructs the proxy to continue operations
628 if the StartTLS operation failed; its use is highly deprecated.
629 If set before any target specification, it affects all targets, unless
630 overridden by any per-target directive.
633 A powerful (and in some sense dangerous) rewrite engine has been added
634 to both the LDAP and Meta backends.
635 While the former can gain limited beneficial effects from rewriting
636 stuff, the latter can become an amazingly powerful tool.
638 Consider a couple of scenarios first.
640 1) Two directory servers share two levels of naming context;
641 say "dc=a,dc=foo,dc=com" and "dc=b,dc=foo,dc=com".
642 Then, an unambiguous Meta database can be configured as:
647 suffix "\fBdc=foo,dc=com\fP"
648 uri "ldap://a.foo.com/dc=a,\fBdc=foo,dc=com\fP"
649 uri "ldap://b.foo.com/dc=b,\fBdc=foo,dc=com\fP"
653 Operations directed to a specific target can be easily resolved
654 because there are no ambiguities.
655 The only operation that may resolve to multiple targets is a search
656 with base "dc=foo,dc=com" and scope at least "one", which results in
657 spawning two searches to the targets.
659 2a) Two directory servers don't share any portion of naming context,
660 but they'd present as a single DIT
661 [Caveat: uniqueness of (massaged) entries among the two servers is
662 assumed; integrity checks risk to incur in excessive overhead and have
663 not been implemented].
664 Say we have "dc=bar,dc=org" and "o=Foo,c=US",
665 and we'd like them to appear as branches of "dc=foo,dc=com", say
666 "dc=a,dc=foo,dc=com" and "dc=b,dc=foo,dc=com".
667 Then we need to configure our Meta backend as:
672 suffix "dc=foo,dc=com"
674 uri "ldap://a.bar.com/\fBdc=a,dc=foo,dc=com\fP"
675 suffixmassage "\fBdc=a,dc=foo,dc=com\fP" "dc=bar,dc=org"
677 uri "ldap://b.foo.com/\fBdc=b,dc=foo,dc=com\fP"
678 suffixmassage "\fBdc=b,dc=foo,dc=com\fP" "o=Foo,c=US"
682 Again, operations can be resolved without ambiguity, although
683 some rewriting is required.
684 Notice that the virtual naming context of each target is a branch of
685 the database's naming context; it is rewritten back and forth when
686 operations are performed towards the target servers.
687 What "back and forth" means will be clarified later.
689 When a search with base "dc=foo,dc=com" is attempted, if the
690 scope is "base" it fails with "no such object"; in fact, the
691 common root of the two targets (prior to massaging) does not
693 If the scope is "one", both targets are contacted with the base
694 replaced by each target's base; the scope is derated to "base".
695 In general, a scope "one" search is honored, and the scope is derated,
696 only when the incoming base is at most one level lower of a target's
697 naming context (prior to massaging).
699 Finally, if the scope is "sub" the incoming base is replaced
700 by each target's unmassaged naming context, and the scope
703 2b) Consider the above reported scenario with the two servers
704 sharing the same naming context:
709 suffix "\fBdc=foo,dc=com\fP"
711 uri "ldap://a.bar.com/\fBdc=foo,dc=com\fP"
712 suffixmassage "\fBdc=foo,dc=com\fP" "dc=bar,dc=org"
714 uri "ldap://b.foo.com/\fBdc=foo,dc=com\fP"
715 suffixmassage "\fBdc=foo,dc=com\fP" "o=Foo,c=US"
719 All the previous considerations hold, except that now there is
720 no way to unambiguously resolve a DN.
721 In this case, all the operations that require an unambiguous target
722 selection will fail unless the DN is already cached or a default
724 Practical configurations may result as a combination of all the
727 Note on ACLs: at present you may add whatever ACL rule you desire
728 to to the Meta (and LDAP) backends.
729 However, the meaning of an ACL on a proxy may require some
731 Two philosophies may be considered:
733 a) the remote server dictates the permissions; the proxy simply passes
734 back what it gets from the remote server.
736 b) the remote server unveils "everything"; the proxy is responsible
737 for protecting data from unauthorized access.
739 Of course the latter sounds unreasonable, but it is not.
740 It is possible to imagine scenarios in which a remote host discloses
741 data that can be considered "public" inside an intranet, and a proxy
742 that connects it to the internet may impose additional constraints.
743 To this purpose, the proxy should be able to comply with all the ACL
744 matching criteria that the server supports.
745 This has been achieved with regard to all the criteria supported by
746 slapd except a special subtle case (please drop me a note if you can
747 find other exceptions: <ando@openldap.org>).
752 access to dn="<dn>" attrs=<attr>
753 by dnattr=<dnattr> read
758 cannot be matched iff the attribute that is being requested, <attr>,
759 is NOT <dnattr>, and the attribute that determines membership,
760 <dnattr>, has not been requested (e.g. in a search)
762 In fact this ACL is resolved by slapd using the portion of entry it
763 retrieved from the remote server without requiring any further
764 intervention of the backend, so, if the <dnattr> attribute has not
765 been fetched, the match cannot be assessed because the attribute is
766 not present, not because no value matches the requirement!
768 Note on ACLs and attribute mapping: ACLs are applied to the mapped
769 attributes; for instance, if the attribute locally known as "foo" is
770 mapped to "bar" on a remote server, then local ACLs apply to attribute
771 "foo" and are totally unaware of its remote name.
772 The remote server will check permissions for "bar", and the local
773 server will possibly enforce additional restrictions to "foo".
775 .\" If this section is moved, also update the reference in
776 .\" libraries/librewrite/RATIONALE.
779 A string is rewritten according to a set of rules, called a `rewrite
781 The rules are based on POSIX (''extended'') regular expressions (regex)
782 with substring matching; basic variable substitution and map resolution
783 of substrings is allowed by specific mechanisms detailed in the following.
784 The behavior of pattern matching/substitution can be altered by a set
787 The underlying concept is to build a lightweight rewrite module
788 for the slapd server (initially dedicated to the LDAP backend).
790 An incoming string is matched against a set of rules.
791 Rules are made of a regex match pattern, a substitution pattern
792 and a set of actions, described by a set of flags.
793 In case of match a string rewriting is performed according to the
794 substitution pattern that allows to refer to substrings matched in the
796 The actions, if any, are finally performed.
797 The substitution pattern allows map resolution of substrings.
798 A map is a generic object that maps a substitution pattern to a value.
799 The flags are divided in "Pattern matching Flags" and "Action Flags";
800 the former alter the regex match pattern behavior while the latter
801 alter the action that is taken after substitution.
802 .SH "Pattern Matching Flags"
805 honors case in matching (default is case insensitive)
808 use POSIX ''basic'' regular expressions (default is ''extended'')
813 recursive passes for a specific rule; does not alter the max total count
814 of passes, so it can only enforce a stricter limit for a specific rule.
818 apply the rule once only (default is recursive)
821 stop applying rules in case of match; the current rule is still applied
822 recursively; combine with `:' to apply the current rule only once
826 stop current operation if the rule matches, and issue an `unwilling to
832 rules back and forth (watch for loops!).
833 Note that `G{1}' is implicit in every rule.
836 ignores errors in rule; this means, in case of error, e.g. issued by a
837 map, the error is treated as a missed match.
838 The `unwilling to perform' is not overridden.
844 as return code if the rule matches; the flag does not alter the recursive
845 behavior of the rule, so, to have it performed only once, it must be used
846 in combination with `:', e.g.
848 returns the value `16' after exactly one execution of the rule, if the
850 As a consequence, its behavior is equivalent to `@', with the return
853 or, in other words, `@' is equivalent to `U{0}'.
854 By convention, the freely available codes are above 16 included;
855 the others are reserved.
857 The ordering of the flags can be significant.
858 For instance: `IG{2}' means ignore errors and jump two lines ahead
859 both in case of match and in case of error, while `G{2}I' means ignore
860 errors, but jump two lines ahead only in case of match.
862 More flags (mainly Action Flags) will be added as needed.
863 .SH "Pattern matching:"
868 .SH "Substitution Pattern Syntax:"
869 Everything starting with `%' requires substitution;
871 the only obvious exception is `%%', which is left as is;
873 the basic substitution is `%d', where `d' is a digit;
874 0 means the whole string, while 1-9 is a submatch;
876 a `%' followed by a `{' invokes an advanced substitution.
880 `%' `{' [ <op> ] <name> `(' <substitution> `)' `}'
883 where <name> must be a legal name for the map, i.e.
887 <name> ::= [a-z][a-z0-9]* (case insensitive)
888 <op> ::= `>' `|' `&' `&&' `*' `**' `$'
892 and <substitution> must be a legal substitution
893 pattern, with no limits on the nesting level.
898 sub context invocation; <name> must be a legal, already defined
902 external command invocation; <name> must refer to a legal, already
903 defined command name (NOT IMPL.)
906 variable assignment; <name> defines a variable in the running
907 operation structure which can be dereferenced later; operator
909 assigns a variable in the rewrite context scope; operator
911 assigns a variable that scopes the entire session, e.g. its value
912 can be dereferenced later by other rewrite contexts
915 variable dereferencing; <name> must refer to a variable that is
916 defined and assigned for the running operation; operator
918 dereferences a variable scoping the rewrite context; operator
920 dereferences a variable scoping the whole session, e.g. the value
921 is passed across rewrite contexts
924 parameter dereferencing; <name> must refer to an existing parameter;
925 the idea is to make some run-time parameters set by the system
926 available to the rewrite engine, as the client host name, the bind DN
927 if any, constant parameters initialized at config time, and so on;
928 no parameter is currently set by either
932 but constant parameters can be defined in the configuration file
937 Substitution escaping has been delegated to the `%' symbol,
938 which is used instead of `\e' in string substitution patterns
939 because `\e' is already escaped by slapd's low level parsing routines;
940 as a consequence, regex escaping requires two `\e' symbols,
941 e.g. `\fB.*\e.foo\e.bar\fP' must be written as `\fB.*\e\e.foo\e\e.bar\fP'.
943 .\" The symbol can be altered at will by redefining the related macro in
946 .SH "Rewrite context:"
947 A rewrite context is a set of rules which are applied in sequence.
948 The basic idea is to have an application initialize a rewrite
949 engine (think of Apache's mod_rewrite ...) with a set of rewrite
950 contexts; when string rewriting is required, one invokes the
951 appropriate rewrite context with the input string and obtains the
952 newly rewritten one if no errors occur.
954 Each basic server operation is associated to a rewrite context;
955 they are divided in two main groups: client \-> server and
956 server \-> client rewriting.
962 (default) if defined and no specific context
967 searchFilterAttrDN search
969 compareAttrDN compare AVA
973 modifyAttrDN modify AVA
977 exopPasswdDN password modify extended operation DN if proxy
985 searchResult search (only if defined; no default;
986 acts on DN and DN-syntax attributes
988 searchAttrDN search AVA
989 matchedDN all ops (only if applicable)
993 .SH "Basic configuration syntax"
995 .B rewriteEngine { on | off }
996 If `on', the requested rewriting is performed; if `off', no
997 rewriting takes place (an easy way to stop rewriting without
998 altering too much the configuration file).
1000 .B rewriteContext <context name> "[ alias <aliased context name> ]"
1001 <Context name> is the name that identifies the context, i.e. the name
1002 used by the application to refer to the set of rules it contains.
1003 It is used also to reference sub contexts in string rewriting.
1004 A context may alias another one.
1005 In this case the alias context contains no rule, and any reference to
1006 it will result in accessing the aliased one.
1008 .B rewriteRule "<regex match pattern>" "<substitution pattern>" "[ <flags> ]"
1009 Determines how a string can be rewritten if a pattern is matched.
1010 Examples are reported below.
1011 .SH "Additional configuration syntax:"
1013 .B rewriteMap "<map type>" "<map name>" "[ <map attrs> ]"
1014 Allows to define a map that transforms substring rewriting into
1016 The map is referenced inside the substitution pattern of a rule.
1018 .B rewriteParam <param name> <param value>
1019 Sets a value with global scope, that can be dereferenced by the
1020 command `%{$paramName}'.
1022 .B rewriteMaxPasses <number of passes> [<number of passes per rule>]
1023 Sets the maximum number of total rewriting passes that can be
1024 performed in a single rewrite operation (to avoid loops).
1025 A safe default is set to 100; note that reaching this limit is still
1026 treated as a success; recursive invocation of rules is simply
1028 The count applies to the rewriting operation as a whole, not
1029 to any single rule; an optional per-rule limit can be set.
1030 This limit is overridden by setting specific per-rule limits
1031 with the `M{n}' flag.
1032 .SH "Configuration examples:"
1034 # set to `off' to disable rewriting
1037 # the rules the "suffixmassage" directive implies
1039 # all dataflow from client to server referring to DNs
1040 rewriteContext default
1041 rewriteRule "(.*)<virtualnamingcontext>$" "%1<realnamingcontext>" ":"
1043 rewriteContext searchFilter
1044 # all dataflow from server to client
1045 rewriteContext searchResult
1046 rewriteRule "(.*)<realnamingcontext>$" "%1<virtualnamingcontext>" ":"
1047 rewriteContext searchAttrDN alias searchResult
1048 rewriteContext matchedDN alias searchResult
1050 # Everything defined here goes into the `default' context.
1051 # This rule changes the naming context of anything sent
1052 # to `dc=home,dc=net' to `dc=OpenLDAP, dc=org'
1054 rewriteRule "(.*)dc=home,[ ]?dc=net"
1055 "%1dc=OpenLDAP, dc=org" ":"
1057 # since a pretty/normalized DN does not include spaces
1058 # after rdn separators, e.g. `,', this rule suffices:
1060 rewriteRule "(.*)dc=home,dc=net"
1061 "%1dc=OpenLDAP,dc=org" ":"
1063 # Start a new context (ends input of the previous one).
1064 # This rule adds blanks between DN parts if not present.
1065 rewriteContext addBlanks
1066 rewriteRule "(.*),([^ ].*)" "%1, %2"
1068 # This one eats blanks
1069 rewriteContext eatBlanks
1070 rewriteRule "(.*),[ ](.*)" "%1,%2"
1072 # Here control goes back to the default rewrite
1073 # context; rules are appended to the existing ones.
1074 # anything that gets here is piped into rule `addBlanks'
1075 rewriteContext default
1076 rewriteRule ".*" "%{>addBlanks(%0)}" ":"
1078 .\" # Anything with `uid=username' is looked up in
1079 .\" # /etc/passwd for gecos (I know it's nearly useless,
1080 .\" # but it is there just as a guideline to implementing
1082 .\" # Note the `I' flag that leaves `uid=username' in place
1083 .\" # if `username' does not have a valid account, and the
1084 .\" # `:' that forces the rule to be processed exactly once.
1085 .\" rewriteContext uid2Gecos
1086 .\" rewriteRule "(.*)uid=([a-z0-9]+),(.+)"
1087 .\" "%1cn=%2{xpasswd},%3" "I:"
1089 .\" # Finally, in a bind, if one uses a `uid=username' DN,
1090 .\" # it is rewritten in `cn=name surname' if possible.
1091 .\" rewriteContext bindDN
1092 .\" rewriteRule ".*" "%{>addBlanks(%{>uid2Gecos(%0)})}" ":"
1094 # Rewrite the search base according to `default' rules.
1095 rewriteContext searchBase alias default
1097 # Search results with OpenLDAP DN are rewritten back with
1098 # `dc=home,dc=net' naming context, with spaces eaten.
1099 rewriteContext searchResult
1100 rewriteRule "(.*[^ ]?)[ ]?dc=OpenLDAP,[ ]?dc=org"
1101 "%{>eatBlanks(%1)}dc=home,dc=net" ":"
1103 # Bind with email instead of full DN: we first need
1104 # an ldap map that turns attributes into a DN (the
1105 # argument used when invoking the map is appended to
1106 # the URI and acts as the filter portion)
1107 rewriteMap ldap attr2dn "ldap://host/dc=my,dc=org?dn?sub"
1109 # Then we need to detect DN made up of a single email,
1110 # e.g. `mail=someone@example.com'; note that the rule
1111 # in case of match stops rewriting; in case of error,
1112 # it is ignored. In case we are mapping virtual
1113 # to real naming contexts, we also need to rewrite
1114 # regular DNs, because the definition of a bindDn
1115 # rewrite context overrides the default definition.
1116 rewriteContext bindDN
1117 rewriteRule "^mail=[^,]+@[^,]+$" "%{attr2dn(%0)}" ":@I"
1119 # This is a rather sophisticated example. It massages a
1120 # search filter in case who performs the search has
1121 # administrative privileges. First we need to keep
1122 # track of the bind DN of the incoming request, which is
1123 # stored in a variable called `binddn' with session scope,
1124 # and left in place to allow regular binding:
1125 rewriteContext bindDN
1126 rewriteRule ".+" "%{&&binddn(%0)}%0" ":"
1128 # A search filter containing `uid=' is rewritten only
1129 # if an appropriate DN is bound.
1130 # To do this, in the first rule the bound DN is
1131 # dereferenced, while the filter is decomposed in a
1132 # prefix, in the value of the `uid=<arg>' AVA, and
1133 # in a suffix. A tag `<>' is appended to the DN.
1134 # If the DN refers to an entry in the `ou=admin' subtree,
1135 # the filter is rewritten OR-ing the `uid=<arg>' with
1136 # `cn=<arg>'; otherwise it is left as is. This could be
1137 # useful, for instance, to allow apache's auth_ldap-1.4
1138 # module to authenticate users with both `uid' and
1139 # `cn', but only if the request comes from a possible
1140 # `cn=Web auth,ou=admin,dc=home,dc=net' user.
1141 rewriteContext searchFilter
1142 rewriteRule "(.*\e\e()uid=([a-z0-9_]+)(\e\e).*)"
1143 "%{**binddn}<>%{&prefix(%1)}%{&arg(%2)}%{&suffix(%3)}"
1145 rewriteRule "[^,]+,ou=admin,dc=home,dc=net"
1146 "%{*prefix}|(uid=%{*arg})(cn=%{*arg})%{*suffix}" ":@I"
1147 rewriteRule ".*<>" "%{*prefix}uid=%{*arg}%{*suffix}" ":"
1149 # This example shows how to strip unwanted DN-valued
1150 # attribute values from a search result; the first rule
1151 # matches DN values below "ou=People,dc=example,dc=com";
1152 # in case of match the rewriting exits successfully.
1153 # The second rule matches everything else and causes
1154 # the value to be rejected.
1155 rewriteContext searchResult
1156 rewriteRule ".*,ou=People,dc=example,dc=com" "%0" ":@"
1157 rewriteRule ".*" "" "#"
1159 .SH "LDAP Proxy resolution (a possible evolution of slapd\-ldap(5)):"
1160 In case the rewritten DN is an LDAP URI, the operation is initiated
1161 towards the host[:port] indicated in the uri, if it does not refer
1162 to the local server.
1166 rewriteRule '^cn=root,.*' '%0' 'G{3}'
1167 rewriteRule '^cn=[a-l].*' 'ldap://ldap1.my.org/%0' ':@'
1168 rewriteRule '^cn=[m-z].*' 'ldap://ldap2.my.org/%0' ':@'
1169 rewriteRule '.*' 'ldap://ldap3.my.org/%0' ':@'
1172 (Rule 1 is simply there to illustrate the `G{n}' action; it could have
1176 rewriteRule '^cn=root,.*' 'ldap://ldap3.my.org/%0' ':@'
1179 with the advantage of saving one rewrite pass ...)
1184 backend does not honor all ACL semantics as described in
1185 .BR slapd.access (5).
1186 In general, access checking is delegated to the remote server(s).
1191 pseudo-attribute and to the other attribute values of the entries
1194 operation is honored, which is performed by the frontend.
1196 .SH PROXY CACHE OVERLAY
1197 The proxy cache overlay
1198 allows caching of LDAP search requests (queries) in a local database.
1200 .BR slapo-pcache (5)
1205 default slapd configuration file
1208 .BR slapd\-ldap (5),
1209 .BR slapo\-pcache (5),
1214 Pierangelo Masarati, based on back-ldap by Howard Chu
projects / openldap / blob