1 .TH SLAPD-META 5 "RELEASEDATE" "OpenLDAP LDVERSION"
2 .\" Copyright 1998-2007 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.
42 Note: When looping back to the same instance of \fBslapd\fP(8),
43 each connection requires a new thread; as a consequence, \fBslapd\fP(8)
44 must be compiled with thread support, and the \fBthreads\fP parameter
45 may need some tuning; in those cases, unless the multiple target feature
46 is required, one may consider using \fBslapd-relay\fP(5) instead,
47 which performs the relayed operation internally and thus reuses
51 There are examples in various places in this document, as well as in the
52 slapd/back-meta/data/ directory in the OpenLDAP source tree.
56 options apply to the META backend database.
57 That is, they must follow a "database meta" line and come before any
58 subsequent "backend" or "database" lines.
59 Other database options are described in the
63 Note: In early versions of back-ldap and back-meta it was recommended to always set
76 This was required because operational attributes related to entry creation
77 and modification should not be proxied, as they could be mistakenly written
78 to the target server(s), generating an error.
79 The current implementation automatically sets lastmod to \fBoff\fP,
80 so its use is redundant and should be omitted.
82 .SH SPECIAL CONFIGURATION DIRECTIVES
83 Target configuration starts with the "uri" directive.
84 All the configuration directives that are not specific to targets
85 should be defined first for clarity, including those that are common
91 This directive causes a cached connection to be dropped an recreated
92 after a given ttl, regardless of being idle or not.
95 .B default-target none
96 This directive forces the backend to reject all those operations
97 that must resolve to a single target in case none or multiple
99 They include: add, delete, modify, modrdn; compare is not included, as
100 well as bind since, as they don't alter entries, in case of multiple
101 matches an attempt is made to perform the operation on any candidate
102 target, with the constraint that at most one must succeed.
103 This directive can also be used when processing targets to mark a
104 specific target as default.
107 .B dncache-ttl {DISABLED|forever|<ttl>}
108 This directive sets the time-to-live of the DN cache.
109 This caches the target that holds a given DN to speed up target
110 selection in case multiple targets would result from an uncached
111 search; forever means cache never expires; disabled means no DN
112 caching; otherwise a valid ( > 0 ) ttl is required, in the format
118 .B onerr {CONTINUE|report|stop}
119 This directive allows to select the behavior in case an error is returned
120 by one target during a search.
121 The default, \fBcontinue\fP, consists in continuing the operation,
122 trying to return as much data as possible.
123 If the value is set to \fBstop\fP, the search is terminated as soon
124 as an error is returned by one target, and the error is immediately
125 propagated to the client.
126 If the value is set to \fBreport\fP, the search is continuated to the end
127 but, in case at least one target returned an error code, the first
128 non-success error code is returned.
131 .B protocol\-version {0,2,3}
132 This directive indicates what protocol version must be used to contact
134 If set to 0 (the default), the proxy uses the same protocol version
135 used by the client, otherwise the requested protocol is used.
136 The proxy returns \fIunwillingToPerform\fP if an operation that is
137 incompatible with the requested protocol is attempted.
138 If set before any target specification, it affects all targets, unless
139 overridden by any per-target directive.
142 .B pseudoroot-bind-defer {NO|yes}
143 This directive, when set to
145 causes the authentication to the remote servers with the pseudo-root
146 identity to be deferred until actually needed by subsequent operations.
149 .B quarantine <interval>,<num>[;<interval>,<num>[...]]
150 Turns on quarantine of URIs that returned
151 .IR LDAP_UNAVAILABLE ,
152 so that an attempt to reconnect only occurs at given intervals instead
153 of any time a client requests an operation.
154 The pattern is: retry only after at least
156 seconds elapsed since last attempt, for exactly
158 times; then use the next pattern.
161 for the last pattern is "\fB+\fP", it retries forever; otherwise,
162 no more retries occur.
163 This directive must appear before any target specification;
164 it affects all targets with the same pattern.
167 .B rebind-as-user {NO|yes}
168 If this option is given, the client's bind credentials are remembered
169 for rebinds, when trying to re-establish a broken connection,
170 or when chasing a referral, if
176 .B session\-tracking\-request {NO|yes}
177 Adds session tracking control for all requests.
178 The client's IP and hostname, and the identity associated to each request,
179 if known, are sent to the remote server for informational purposes.
180 This directive is incompatible with setting \fIprotocol\-version\fP to 2.
181 If set before any target specification, it affects all targets, unless
182 overridden by any per-target directive.
185 .B single\-conn {NO|yes}
186 Discards current cached connection when the client rebinds.
189 .B use-temporary-conn {NO|yes}
192 create a temporary connection whenever competing with other threads
193 for a shared one; otherwise, wait until the shared connection is available.
195 .SH TARGET SPECIFICATION
196 Target specification starts with a "uri" directive:
199 .B uri <protocol>://[<host>]/<naming context> [...]
200 The <protocol> part can be anything
201 .BR ldap_initialize (3)
202 accepts ({ldap|ldaps|ldapi} and variants); the <host> may be
203 omitted, defaulting to whatever is set in
205 The <naming context> part is \fImandatory\fP for the first URI,
206 but it \fImust be omitted\fP for subsequent ones, if any.
207 The naming context part must be within the naming context defined for the backend,
212 suffix "\fBdc=foo,dc=com\fP"
213 uri "ldap://x.foo.com/dc=x,\fBdc=foo,dc=com\fP"
218 The <naming context> part doesn't need to be unique across the targets;
219 it may also match one of the values of the "suffix" directive.
220 Multiple URIs may be defined in a single URI statement.
221 The additional URIs must be separate arguments and must not have any
222 <naming context> part. This causes the underlying library
223 to contact the first server of the list that responds.
224 For example, if \fIl1.foo.com\fP and \fIl2.foo.com\fP are shadows
225 of the same server, the directive
228 suffix "\fBdc=foo,dc=com\fP"
229 uri "ldap://l1.foo.com/\fBdc=foo,dc=com\fP" "ldap://l2.foo.com/"
234 causes \fIl2.foo.com\fP to be contacted whenever \fIl1.foo.com\fP
236 In that case, the URI list is internally rearranged, by moving unavailable
237 URIs to the end, so that further connection attempts occur with respect to
238 the last URI that succeeded.
242 .B acl-authcDN "<administrative DN for access control purposes>"
243 DN which is used to query the target server for acl checking,
244 as in the LDAP backend; it is supposed to have read access
245 on the target server to attributes used on the proxy for acl checking.
246 There is no risk of giving away such values; they are only used to
248 .B The acl-authcDN identity is by no means implicitly used by the proxy
249 .B when the client connects anonymously.
252 .B acl-passwd <password>
253 Password used with the
259 .B bind-timeout <microseconds>
260 This directive defines the timeout, in microseconds, used when polling
261 for response after an asynchronous bind connection. The initial call
262 to ldap_result(3) is performed with a trade-off timeout of 100000 us;
263 if that results in a timeout exceeded, subsequent calls use the value
266 The default value is used also for subsequent calls if
269 If set before any target specification, it affects all targets, unless
270 overridden by any per-target directive.
273 .B chase-referrals {YES|no}
274 enable/disable automatic referral chasing, which is delegated to the
275 underlying libldap, with rebinding eventually performed if the
276 \fBrebind-as-user\fP directive is used. The default is to chase referrals.
277 If set before any target specification, it affects all targets, unless
278 overridden by any per-target directive.
281 .B default-target [<target>]
282 The "default-target" directive can also be used during target specification.
283 With no arguments it marks the current target as the default.
284 The optional number marks target <target> as the default one, starting
286 Target <target> must be defined.
289 .B idle-timeout <time>
290 This directive causes a cached connection to be dropped an recreated
291 after it has been idle for the specified time.
292 The value can be specified as
294 [<d>d][<h>h][<m>m][<s>[s]]
296 where <d>, <h>, <m> and <s> are respectively treated as days, hours,
298 If set before any target specification, it affects all targets, unless
299 overridden by any per-target directive.
302 .B map "{attribute|objectclass} [<local name>|*] {<foreign name>|*}"
303 This maps object classes and attributes as in the LDAP backend.
308 .B network-timeout <time>
309 Sets the network timeout value after which
310 .BR poll (2)/ select (2)
313 returns in case of no activity.
314 The value is in seconds, and it can be specified as for
316 If set before any target specification, it affects all targets, unless
317 overridden by any per-target directive.
320 .B nretries {forever|never|<nretries>}
321 This directive defines how many times a bind should be retried
322 in case of temporary failure in contacting a target. If defined
323 before any target specification, it applies to all targets (by default,
326 the global value can be overridden by redefinitions inside each target
330 .B pseudorootdn "<substitute DN in case of rootdn bind>"
331 This directive, if present, sets the DN that will be substituted to
332 the bind DN if a bind with the backend's "rootdn" succeeds.
333 The true "rootdn" of the target server ought not be used; an arbitrary
334 administrative DN should used instead.
337 .B pseudorootpw "<substitute password in case of rootdn bind>"
338 This directive sets the credential that will be used in case a bind
339 with the backend's "rootdn" succeeds, and the bind is propagated to
340 the target using the "pseudorootdn" DN.
342 Note: cleartext credentials must be supplied here; as a consequence,
343 using the pseudorootdn/pseudorootpw directives is inherently unsafe.
347 The rewrite options are described in the "REWRITING" section.
350 .B subtree-exclude "<DN>"
351 This directive instructs back-meta to ignore the current target
352 for operations whose requestDN is subordinate to
354 There may be multiple occurrences of the
356 directive for each of the targets.
359 .B suffixmassage "<virtual naming context>" "<real naming context>"
360 All the directives starting with "rewrite" refer to the rewrite engine
361 that has been added to slapd.
362 The "suffixmassage" directive was introduced in the LDAP backend to
363 allow suffix massaging while proxying.
364 It has been obsoleted by the rewriting tools.
365 However, both for backward compatibility and for ease of configuration
366 when simple suffix massage is required, it has been preserved.
367 It wraps the basic rewriting instructions that perform suffix
368 massaging. See the "REWRITING" section for a detailed list
369 of the rewrite rules it implies.
372 .B t-f-support {NO|yes|discover}
373 enable if the remote server supports absolute filters
374 (see \fIdraft-zeilenga-ldap-t-f\fP for details).
377 support is detected by reading the remote server's root DSE.
378 If set before any target specification, it affects all targets, unless
379 overridden by any per-target directive.
382 .B timeout [<op>=]<val> [...]
383 This directive allows to set per-operation timeouts.
386 \fB<op> ::= bind, add, delete, modrdn, modify, compare, search\fP
388 The overall duration of the \fBsearch\fP operation is controlled either
389 by the \fBtimelimit\fP parameter or by server-side enforced
390 time limits (see \fBtimelimit\fP and \fBlimits\fP in
393 This \fBtimeout\fP parameter controls how long the target can be
394 irresponsive before the operation is aborted.
395 Timeout is meaningless for the remaining operations,
396 \fBunbind\fP and \fBabandon\fP, which do not imply any response,
397 while it is not yet implemented in currently supported \fBextended\fP
399 If no operation is specified, the timeout \fBval\fP affects all
400 supported operations.
401 If specified before any target definition, it affects all targets
402 unless overridden by per-target directives.
404 Note: if the timeout is exceeded, the operation is cancelled
405 (according to the \fBcancel\fP directive);
406 the protocol does not provide any means to rollback operations,
407 so the client will not be notified about the result of the operation,
408 which may eventually succeeded or not.
409 In case the timeout is exceeded during a bind operation, the connection
410 is destroyed, according to RFC4511.
413 .B tls {[try-]start|[try-]propagate}
414 execute the StartTLS extended operation when the connection is initialized;
415 only works if the URI directive protocol scheme is not \fBldaps://\fP.
416 \fBpropagate\fP issues the StartTLS operation only if the original
418 The \fBtry-\fP prefix instructs the proxy to continue operations
419 if the StartTLS operation failed; its use is highly deprecated.
420 If set before any target specification, it affects all targets, unless
421 overridden by any per-target directive.
424 A powerful (and in some sense dangerous) rewrite engine has been added
425 to both the LDAP and Meta backends.
426 While the former can gain limited beneficial effects from rewriting
427 stuff, the latter can become an amazingly powerful tool.
429 Consider a couple of scenarios first.
431 1) Two directory servers share two levels of naming context;
432 say "dc=a,dc=foo,dc=com" and "dc=b,dc=foo,dc=com".
433 Then, an unambiguous Meta database can be configured as:
438 suffix "\fBdc=foo,dc=com\fP"
439 uri "ldap://a.foo.com/dc=a,\fBdc=foo,dc=com\fP"
440 uri "ldap://b.foo.com/dc=b,\fBdc=foo,dc=com\fP"
444 Operations directed to a specific target can be easily resolved
445 because there are no ambiguities.
446 The only operation that may resolve to multiple targets is a search
447 with base "dc=foo,dc=com" and scope at least "one", which results in
448 spawning two searches to the targets.
450 2a) Two directory servers don't share any portion of naming context,
451 but they'd present as a single DIT
452 [Caveat: uniqueness of (massaged) entries among the two servers is
453 assumed; integrity checks risk to incur in excessive overhead and have
454 not been implemented].
455 Say we have "dc=bar,dc=org" and "o=Foo,c=US",
456 and we'd like them to appear as branches of "dc=foo,dc=com", say
457 "dc=a,dc=foo,dc=com" and "dc=b,dc=foo,dc=com".
458 Then we need to configure our Meta backend as:
463 suffix "dc=foo,dc=com"
465 uri "ldap://a.bar.com/\fBdc=a,dc=foo,dc=com\fP"
466 suffixmassage "\fBdc=a,dc=foo,dc=com\fP" "dc=bar,dc=org"
468 uri "ldap://b.foo.com/\fBdc=b,dc=foo,dc=com\fP"
469 suffixmassage "\fBdc=b,dc=foo,dc=com\fP" "o=Foo,c=US"
473 Again, operations can be resolved without ambiguity, although
474 some rewriting is required.
475 Notice that the virtual naming context of each target is a branch of
476 the database's naming context; it is rewritten back and forth when
477 operations are performed towards the target servers.
478 What "back and forth" means will be clarified later.
480 When a search with base "dc=foo,dc=com" is attempted, if the
481 scope is "base" it fails with "no such object"; in fact, the
482 common root of the two targets (prior to massaging) does not
484 If the scope is "one", both targets are contacted with the base
485 replaced by each target's base; the scope is derated to "base".
486 In general, a scope "one" search is honored, and the scope is derated,
487 only when the incoming base is at most one level lower of a target's
488 naming context (prior to massaging).
490 Finally, if the scope is "sub" the incoming base is replaced
491 by each target's unmassaged naming context, and the scope
494 2b) Consider the above reported scenario with the two servers
495 sharing the same naming context:
500 suffix "\fBdc=foo,dc=com\fP"
502 uri "ldap://a.bar.com/\fBdc=foo,dc=com\fP"
503 suffixmassage "\fBdc=foo,dc=com\fP" "dc=bar,dc=org"
505 uri "ldap://b.foo.com/\fBdc=foo,dc=com\fP"
506 suffixmassage "\fBdc=foo,dc=com\fP" "o=Foo,c=US"
510 All the previous considerations hold, except that now there is
511 no way to unambiguously resolve a DN.
512 In this case, all the operations that require an unambiguous target
513 selection will fail unless the DN is already cached or a default
515 Practical configurations may result as a combination of all the
518 Note on ACLs: at present you may add whatever ACL rule you desire
519 to to the Meta (and LDAP) backends.
520 However, the meaning of an ACL on a proxy may require some
522 Two philosophies may be considered:
524 a) the remote server dictates the permissions; the proxy simply passes
525 back what it gets from the remote server.
527 b) the remote server unveils "everything"; the proxy is responsible
528 for protecting data from unauthorized access.
530 Of course the latter sounds unreasonable, but it is not.
531 It is possible to imagine scenarios in which a remote host discloses
532 data that can be considered "public" inside an intranet, and a proxy
533 that connects it to the internet may impose additional constraints.
534 To this purpose, the proxy should be able to comply with all the ACL
535 matching criteria that the server supports.
536 This has been achieved with regard to all the criteria supported by
537 slapd except a special subtle case (please drop me a note if you can
538 find other exceptions: <ando@openldap.org>).
543 access to dn="<dn>" attrs=<attr>
544 by dnattr=<dnattr> read
549 cannot be matched iff the attribute that is being requested, <attr>,
550 is NOT <dnattr>, and the attribute that determines membership,
551 <dnattr>, has not been requested (e.g. in a search)
553 In fact this ACL is resolved by slapd using the portion of entry it
554 retrieved from the remote server without requiring any further
555 intervention of the backend, so, if the <dnattr> attribute has not
556 been fetched, the match cannot be assessed because the attribute is
557 not present, not because no value matches the requirement!
559 Note on ACLs and attribute mapping: ACLs are applied to the mapped
560 attributes; for instance, if the attribute locally known as "foo" is
561 mapped to "bar" on a remote server, then local ACLs apply to attribute
562 "foo" and are totally unaware of its remote name.
563 The remote server will check permissions for "bar", and the local
564 server will possibly enforce additional restrictions to "foo".
566 .\" If this section is moved, also update the reference in
567 .\" libraries/librewrite/RATIONALE.
570 A string is rewritten according to a set of rules, called a `rewrite
572 The rules are based on POSIX (''extended'') regular expressions (regex)
573 with substring matching; basic variable substitution and map resolution
574 of substrings is allowed by specific mechanisms detailed in the following.
575 The behavior of pattern matching/substitution can be altered by a set
578 The underlying concept is to build a lightweight rewrite module
579 for the slapd server (initially dedicated to the LDAP backend).
581 An incoming string is matched against a set of rules.
582 Rules are made of a regex match pattern, a substitution pattern
583 and a set of actions, described by a set of flags.
584 In case of match a string rewriting is performed according to the
585 substitution pattern that allows to refer to substrings matched in the
587 The actions, if any, are finally performed.
588 The substitution pattern allows map resolution of substrings.
589 A map is a generic object that maps a substitution pattern to a value.
590 The flags are divided in "Pattern matching Flags" and "Action Flags";
591 the former alter the regex match pattern behavior while the latter
592 alter the action that is taken after substitution.
593 .SH "Pattern Matching Flags"
596 honors case in matching (default is case insensitive)
599 use POSIX ''basic'' regular expressions (default is ''extended'')
604 recursive passes for a specific rule; does not alter the max total count
605 of passes, so it can only enforce a stricter limit for a specific rule.
609 apply the rule once only (default is recursive)
612 stop applying rules in case of match; the current rule is still applied
613 recursively; combine with `:' to apply the current rule only once
617 stop current operation if the rule matches, and issue an `unwilling to
623 rules back and forth (watch for loops!).
624 Note that `G{1}' is implicit in every rule.
627 ignores errors in rule; this means, in case of error, e.g. issued by a
628 map, the error is treated as a missed match.
629 The `unwilling to perform' is not overridden.
635 as return code if the rule matches; the flag does not alter the recursive
636 behavior of the rule, so, to have it performed only once, it must be used
637 in combination with `:', e.g.
639 returns the value `16' after exactly one execution of the rule, if the
641 As a consequence, its behavior is equivalent to `@', with the return
644 or, in other words, `@' is equivalent to `U{0}'.
645 By convention, the freely available codes are above 16 included;
646 the others are reserved.
648 The ordering of the flags can be significant.
649 For instance: `IG{2}' means ignore errors and jump two lines ahead
650 both in case of match and in case of error, while `G{2}I' means ignore
651 errors, but jump two lines ahead only in case of match.
653 More flags (mainly Action Flags) will be added as needed.
654 .SH "Pattern matching:"
659 .SH "Substitution Pattern Syntax:"
660 Everything starting with `%' requires substitution;
662 the only obvious exception is `%%', which is left as is;
664 the basic substitution is `%d', where `d' is a digit;
665 0 means the whole string, while 1-9 is a submatch;
667 a `%' followed by a `{' invokes an advanced substitution.
671 `%' `{' [ <op> ] <name> `(' <substitution> `)' `}'
674 where <name> must be a legal name for the map, i.e.
678 <name> ::= [a-z][a-z0-9]* (case insensitive)
679 <op> ::= `>' `|' `&' `&&' `*' `**' `$'
683 and <substitution> must be a legal substitution
684 pattern, with no limits on the nesting level.
689 sub context invocation; <name> must be a legal, already defined
693 external command invocation; <name> must refer to a legal, already
694 defined command name (NOT IMPL.)
697 variable assignment; <name> defines a variable in the running
698 operation structure which can be dereferenced later; operator
700 assigns a variable in the rewrite context scope; operator
702 assigns a variable that scopes the entire session, e.g. its value
703 can be dereferenced later by other rewrite contexts
706 variable dereferencing; <name> must refer to a variable that is
707 defined and assigned for the running operation; operator
709 dereferences a variable scoping the rewrite context; operator
711 dereferences a variable scoping the whole session, e.g. the value
712 is passed across rewrite contexts
715 parameter dereferencing; <name> must refer to an existing parameter;
716 the idea is to make some run-time parameters set by the system
717 available to the rewrite engine, as the client host name, the bind DN
718 if any, constant parameters initialized at config time, and so on;
719 no parameter is currently set by either
723 but constant parameters can be defined in the configuration file
728 Substitution escaping has been delegated to the `%' symbol,
729 which is used instead of `\e' in string substitution patterns
730 because `\e' is already escaped by slapd's low level parsing routines;
731 as a consequence, regex escaping requires two `\e' symbols,
732 e.g. `\fB.*\e.foo\e.bar\fP' must be written as `\fB.*\e\e.foo\e\e.bar\fP'.
734 .\" The symbol can be altered at will by redefining the related macro in
737 .SH "Rewrite context:"
738 A rewrite context is a set of rules which are applied in sequence.
739 The basic idea is to have an application initialize a rewrite
740 engine (think of Apache's mod_rewrite ...) with a set of rewrite
741 contexts; when string rewriting is required, one invokes the
742 appropriate rewrite context with the input string and obtains the
743 newly rewritten one if no errors occur.
745 Each basic server operation is associated to a rewrite context;
746 they are divided in two main groups: client \-> server and
747 server \-> client rewriting.
753 (default) if defined and no specific context
758 searchFilterAttrDN search
760 compareAttrDN compare AVA
764 modifyAttrDN modify AVA
768 exopPasswdDN password modify extended operation DN if proxy
776 searchResult search (only if defined; no default;
777 acts on DN and DN-syntax attributes
779 searchAttrDN search AVA
780 matchedDN all ops (only if applicable)
784 .SH "Basic configuration syntax"
786 .B rewriteEngine { on | off }
787 If `on', the requested rewriting is performed; if `off', no
788 rewriting takes place (an easy way to stop rewriting without
789 altering too much the configuration file).
791 .B rewriteContext <context name> "[ alias <aliased context name> ]"
792 <Context name> is the name that identifies the context, i.e. the name
793 used by the application to refer to the set of rules it contains.
794 It is used also to reference sub contexts in string rewriting.
795 A context may alias another one.
796 In this case the alias context contains no rule, and any reference to
797 it will result in accessing the aliased one.
799 .B rewriteRule "<regex match pattern>" "<substitution pattern>" "[ <flags> ]"
800 Determines how a string can be rewritten if a pattern is matched.
801 Examples are reported below.
802 .SH "Additional configuration syntax:"
804 .B rewriteMap "<map type>" "<map name>" "[ <map attrs> ]"
805 Allows to define a map that transforms substring rewriting into
807 The map is referenced inside the substitution pattern of a rule.
809 .B rewriteParam <param name> <param value>
810 Sets a value with global scope, that can be dereferenced by the
811 command `%{$paramName}'.
813 .B rewriteMaxPasses <number of passes> [<number of passes per rule>]
814 Sets the maximum number of total rewriting passes that can be
815 performed in a single rewrite operation (to avoid loops).
816 A safe default is set to 100; note that reaching this limit is still
817 treated as a success; recursive invocation of rules is simply
819 The count applies to the rewriting operation as a whole, not
820 to any single rule; an optional per-rule limit can be set.
821 This limit is overridden by setting specific per-rule limits
822 with the `M{n}' flag.
823 .SH "Configuration examples:"
825 # set to `off' to disable rewriting
828 # the rules the "suffixmassage" directive implies
830 # all dataflow from client to server referring to DNs
831 rewriteContext default
832 rewriteRule "(.*)<virtualnamingcontext>$" "%1<realnamingcontext>" ":"
834 rewriteContext searchFilter
835 # all dataflow from server to client
836 rewriteContext searchResult
837 rewriteRule "(.*)<realnamingcontext>$" "%1<virtualnamingcontext>" ":"
838 rewriteContext searchAttrDN alias searchResult
839 rewriteContext matchedDN alias searchResult
841 # Everything defined here goes into the `default' context.
842 # This rule changes the naming context of anything sent
843 # to `dc=home,dc=net' to `dc=OpenLDAP, dc=org'
845 rewriteRule "(.*)dc=home,[ ]?dc=net"
846 "%1dc=OpenLDAP, dc=org" ":"
848 # since a pretty/normalized DN does not include spaces
849 # after rdn separators, e.g. `,', this rule suffices:
851 rewriteRule "(.*)dc=home,dc=net"
852 "%1dc=OpenLDAP,dc=org" ":"
854 # Start a new context (ends input of the previous one).
855 # This rule adds blanks between DN parts if not present.
856 rewriteContext addBlanks
857 rewriteRule "(.*),([^ ].*)" "%1, %2"
859 # This one eats blanks
860 rewriteContext eatBlanks
861 rewriteRule "(.*),[ ](.*)" "%1,%2"
863 # Here control goes back to the default rewrite
864 # context; rules are appended to the existing ones.
865 # anything that gets here is piped into rule `addBlanks'
866 rewriteContext default
867 rewriteRule ".*" "%{>addBlanks(%0)}" ":"
869 .\" # Anything with `uid=username' is looked up in
870 .\" # /etc/passwd for gecos (I know it's nearly useless,
871 .\" # but it is there just as a guideline to implementing
873 .\" # Note the `I' flag that leaves `uid=username' in place
874 .\" # if `username' does not have a valid account, and the
875 .\" # `:' that forces the rule to be processed exactly once.
876 .\" rewriteContext uid2Gecos
877 .\" rewriteRule "(.*)uid=([a-z0-9]+),(.+)"
878 .\" "%1cn=%2{xpasswd},%3" "I:"
880 .\" # Finally, in a bind, if one uses a `uid=username' DN,
881 .\" # it is rewritten in `cn=name surname' if possible.
882 .\" rewriteContext bindDN
883 .\" rewriteRule ".*" "%{>addBlanks(%{>uid2Gecos(%0)})}" ":"
885 # Rewrite the search base according to `default' rules.
886 rewriteContext searchBase alias default
888 # Search results with OpenLDAP DN are rewritten back with
889 # `dc=home,dc=net' naming context, with spaces eaten.
890 rewriteContext searchResult
891 rewriteRule "(.*[^ ]?)[ ]?dc=OpenLDAP,[ ]?dc=org"
892 "%{>eatBlanks(%1)}dc=home,dc=net" ":"
894 # Bind with email instead of full DN: we first need
895 # an ldap map that turns attributes into a DN (the
896 # argument used when invoking the map is appended to
897 # the URI and acts as the filter portion)
898 rewriteMap ldap attr2dn "ldap://host/dc=my,dc=org?dn?sub"
900 # Then we need to detect DN made up of a single email,
901 # e.g. `mail=someone@example.com'; note that the rule
902 # in case of match stops rewriting; in case of error,
903 # it is ignored. In case we are mapping virtual
904 # to real naming contexts, we also need to rewrite
905 # regular DNs, because the definition of a bindDn
906 # rewrite context overrides the default definition.
907 rewriteContext bindDN
908 rewriteRule "^mail=[^,]+@[^,]+$" "%{attr2dn(%0)}" ":@I"
910 # This is a rather sophisticated example. It massages a
911 # search filter in case who performs the search has
912 # administrative privileges. First we need to keep
913 # track of the bind DN of the incoming request, which is
914 # stored in a variable called `binddn' with session scope,
915 # and left in place to allow regular binding:
916 rewriteContext bindDN
917 rewriteRule ".+" "%{&&binddn(%0)}%0" ":"
919 # A search filter containing `uid=' is rewritten only
920 # if an appropriate DN is bound.
921 # To do this, in the first rule the bound DN is
922 # dereferenced, while the filter is decomposed in a
923 # prefix, in the value of the `uid=<arg>' AVA, and
924 # in a suffix. A tag `<>' is appended to the DN.
925 # If the DN refers to an entry in the `ou=admin' subtree,
926 # the filter is rewritten OR-ing the `uid=<arg>' with
927 # `cn=<arg>'; otherwise it is left as is. This could be
928 # useful, for instance, to allow apache's auth_ldap-1.4
929 # module to authenticate users with both `uid' and
930 # `cn', but only if the request comes from a possible
931 # `cn=Web auth,ou=admin,dc=home,dc=net' user.
932 rewriteContext searchFilter
933 rewriteRule "(.*\e\e()uid=([a-z0-9_]+)(\e\e).*)"
934 "%{**binddn}<>%{&prefix(%1)}%{&arg(%2)}%{&suffix(%3)}"
936 rewriteRule "[^,]+,ou=admin,dc=home,dc=net"
937 "%{*prefix}|(uid=%{*arg})(cn=%{*arg})%{*suffix}" ":@I"
938 rewriteRule ".*<>" "%{*prefix}uid=%{*arg}%{*suffix}" ":"
940 # This example shows how to strip unwanted DN-valued
941 # attribute values from a search result; the first rule
942 # matches DN values below "ou=People,dc=example,dc=com";
943 # in case of match the rewriting exits successfully.
944 # The second rule matches everything else and causes
945 # the value to be rejected.
946 rewriteContext searchResult
947 rewriteRule ".*,ou=People,dc=example,dc=com" "%0" ":@"
948 rewriteRule ".*" "" "#"
950 .SH "LDAP Proxy resolution (a possible evolution of slapd\-ldap(5)):"
951 In case the rewritten DN is an LDAP URI, the operation is initiated
952 towards the host[:port] indicated in the uri, if it does not refer
957 rewriteRule '^cn=root,.*' '%0' 'G{3}'
958 rewriteRule '^cn=[a-l].*' 'ldap://ldap1.my.org/%0' ':@'
959 rewriteRule '^cn=[m-z].*' 'ldap://ldap2.my.org/%0' ':@'
960 rewriteRule '.*' 'ldap://ldap3.my.org/%0' ':@'
963 (Rule 1 is simply there to illustrate the `G{n}' action; it could have
967 rewriteRule '^cn=root,.*' 'ldap://ldap3.my.org/%0' ':@'
970 with the advantage of saving one rewrite pass ...)
975 backend does not honor all ACL semantics as described in
976 .BR slapd.access (5).
977 In general, access checking is delegated to the remote server(s).
982 pseudo-attribute and to the other attribute values of the entries
985 operation is honored, which is performed by the frontend.
987 .SH PROXY CACHE OVERLAY
988 The proxy cache overlay
989 allows caching of LDAP search requests (queries) in a local database.
996 default slapd configuration file
1000 .BR slapo\-pcache (5),
1005 Pierangelo Masarati, based on back-ldap by Howard Chu