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slapd-ldap (5oldap)

Name

slapd-ldap - LDAP backend to slapd

Synopsis

/etc/openldap/slapd.conf

Description

SLAPD-LDAP(5oldap)                                          SLAPD-LDAP(5oldap)



NAME
       slapd-ldap - LDAP backend to slapd

SYNOPSIS
       /etc/openldap/slapd.conf

DESCRIPTION
       The LDAP backend to slapd(8) is not an actual database; instead it acts
       as a proxy to forward incoming requests to another LDAP  server.  While
       processing requests it will also chase referrals, so that referrals are
       fully processed instead of being returned to the slapd client.

       Sessions that explicitly Bind to the back-ldap database  always  create
       their  own private connection to the remote LDAP server. Anonymous ses-
       sions will share a single anonymous connection to  the  remote  server.
       For sessions bound through other mechanisms, all sessions with the same
       DN will share the same connection. This connection pooling strategy can
       enhance  the  proxy's efficiency by reducing the overhead of repeatedly
       making/breaking multiple connections.

       The ldap database can also act as  an  information  service,  i.e.  the
       identity  of  locally  authenticated  clients is asserted to the remote
       server, possibly in some modified form.  For this  purpose,  the  proxy
       binds  to  the remote server with some administrative identity, and, if
       required, authorizes the asserted identity.  See the  idassert-*  rules
       below.  The administrative identity of the proxy, on the remote server,
       must be allowed to authorize by means of appropriate authzTo rules; see
       slapd.conf(5) for details.

       The  proxy instance of slapd(8) must contain schema information for the
       attributes and objectClasses used in filters, request DNs and  request-
       related data in general.  It should also contain schema information for
       the data returned by the proxied server.  It is the  responsibility  of
       the  proxy  administrator to keep the schema of the proxy lined up with
       that of the proxied server.


       Note: When looping back to the same instance of slapd(8), each  connec-
       tion requires a new thread; as a consequence, slapd(8) must be compiled
       with thread support, and the threads parameter may need some tuning; in
       those  cases, one may consider using slapd-relay(5) instead, which per-
       forms the relayed operation internally and thus reuses the same connec-
       tion.


CONFIGURATION
       These  slapd.conf options apply to the LDAP backend database.  That is,
       they must follow a "database ldap" line and come before any  subsequent
       "backend" or "database" lines.  Other database options are described in
       the slapd.conf(5) manual page.


       Note: In early versions of back-ldap it was recommended to always set

              lastmod  off

       for ldap and meta databases.  This  was  required  because  operational
       attributes  related  to  entry  creation and modification should not be
       proxied, as they could be mistakenly written to the  target  server(s),
       generating  an  error.   The  current implementation automatically sets
       lastmod to off, so its use is redundant and should be omitted.


       uri <ldapurl>
              LDAP server to use.  Multiple URIs can be set in a  single  lda-
              purl argument, resulting in the underlying library automatically
              calling the first server of the list that responds, e.g.

              uri "ldap://host/ ldap://backup-host/"

              The URI list is space- or comma-separated.  Whenever the  server
              that  responds  is  not  the  first one in the list, the list is
              rearranged and the responsive server is moved to  the  head,  so
              that it will be first contacted the next time a connection needs
              to be created.

       acl-bind       bindmethod=simple|sasl       [binddn=<simple        DN>]
              [credentials=<simple     password>]    [saslmech=<SASL    mech>]
              [secprops=<properties>] [realm=<realm>] [authcId=<authentication
              ID>]   [authzId=<authorization  ID>]  [starttls=no|yes|critical]
              [tls_cert=<file>]      [tls_key=<file>]      [tls_cacert=<file>]
              [tls_cacertdir=<path>]      [tls_reqcert=never|allow|try|demand]
              [tls_cipher_suite=<ciphers>]
              [tls_protocol_min=<major>[.<minor>]]
              [tls_crlcheck=none|peer|all]
              Allows one to define the parameters of the authentication method
              that  is internally used by the proxy to collect info related to
              access control,  and  whenever  an  operation  occurs  with  the
              identity of the rootdn of the LDAP proxy database.  The identity
              defined  by  this  directive,  according   to   the   properties
              associated  to  the  authentication  method, is supposed to have
              read access on the target server to attributes used on the proxy
              for ACL checking.

              There  is no risk of giving away such values; they are only used
              to check permissions.  The default is to use simple  bind,  with
              empty  binddn  and  credentials,  which  means  that the related
              operations will be performed anonymously.  If not  set,  and  if
              idassert-bind  is defined, this latter identity is used instead.
              See idassert-bind for details.

              The connection between the proxy database and the remote  server
              associated to this identity is cached regardless of the lifespan
              of the client-proxy connection that first established it.

              This identity is not implicitly  used  by  the  proxy  when  the
              client   connects   anonymously.    The  idassert-bind  feature,
              instead,  in  some  cases  can  be  crafted  to  implement  that
              behavior,  which is intrinsically unsafe and should be used with
              extreme  care.   This  directive  obsoletes   acl-authcDN,   and
              acl-passwd.

              The  TLS  settings  default  to  the  same as the main slapd TLS
              settings, except for tls_reqcert which defaults to "demand".


       cancel {ABANDON|ignore|exop[-discover]}
              Defines how  to  handle  operation  cancellation.   By  default,
              abandon  is  invoked, so the operation is abandoned immediately.
              If set to ignore, no action is taken and any further response is
              ignored;  this  may  result  in  further response messages to be
              queued for that connection,  so  it  is  recommended  that  long
              lasting  connections  are  timed  out  either by idle-timeout or
              conn-ttl, so that resources eventually get released.  If set  to
              exop,  a cancel operation (RFC 3909) is issued, resulting in the
              cancellation of the  current  operation;  the  cancel  operation
              waits  for  remote  server  response,  so  its  use  may  not be
              recommended.  If set to exop-discover,  support  of  the  cancel
              extended  operation  is  detected by reading the remote server's
              root DSE.


       chase-referrals {YES|no}
              enable/disable automatic referral chasing, which is delegated to
              the  underlying  libldap, with rebinding eventually performed if
              the rebind-as-user directive is used.  The default is  to  chase
              referrals.


       conn-ttl <time>
              This  directive  causes  a  cached  connection to be dropped and
              recreated after a given ttl, regardless of being idle or not.


       idassert-authzFrom <authz-regexp>
              if defined, selects what  local  identities  are  authorized  to
              exploit  the  identity  assertion  feature.   The string <authz-
              regexp> follows the rules defined for the  authzFrom  attribute.
              See  slapd.conf(5), section related to authz-policy, for details
              on the syntax of this field.


       idassert-bind    bindmethod=none|simple|sasl    [binddn=<simple    DN>]
              [credentials=<simple     password>]    [saslmech=<SASL    mech>]
              [secprops=<properties>] [realm=<realm>] [authcId=<authentication
              ID>]  [authzId=<authorization  ID>]  [authz={native|proxyauthz}]
              [mode=<mode>]     [flags=<flags>]     [starttls=no|yes|critical]
              [tls_cert=<file>]      [tls_key=<file>]      [tls_cacert=<file>]
              [tls_cacertdir=<path>]      [tls_reqcert=never|allow|try|demand]
              [tls_cipher_suite=<ciphers>]        [tls_protocol_min=<version>]
              [tls_crlcheck=none|peer|all]
              Allows one to define the parameters of the authentication method
              that  is  internally  used by the proxy to authorize connections
              that are authenticated by other  databases.   Direct  binds  are
              always proxied without any idassert handling.

              The  identity  defined  by  this  directive,  according  to  the
              properties associated to the authentication method, is  supposed
              to  have  auth access on the target server to attributes used on
              the proxy  for  authentication  and  authorization,  and  to  be
              allowed   to   authorize  the  users.   This  requires  to  have
              proxyAuthz   privileges   on   a   wide   set   of   DNs,   e.g.
              authzTo=dn.subtree:"",   and   the   remote   server   to   have
              authz-policy set to to or both.  See slapd.conf(5)  for  details
              on  these  statements  and for remarks and drawbacks about their
              usage.  The supported bindmethods are

              none|simple|sasl

              where none  is  the  default,  i.e.  no  identity  assertion  is
              performed.

              The authz parameter is used to instruct the SASL bind to exploit
              native SASL authorization, if available; since  connections  are
              cached,  this  should only be used when authorizing with a fixed
              identity (e.g. by means of the authzDN or  authzID  parameters).
              Otherwise,  the  default proxyauthz is used, i.e. the proxyAuthz
              control (Proxied  Authorization,  RFC  4370)  is  added  to  all
              operations.

              The supported modes are:

              <mode> := {legacy|anonymous|none|self}

              If <mode> is not present, and authzId is given, the proxy always
              authorizes that identity.  <authorization ID> can be

              u:<user>

              [dn:]<DN>

              The former is supposed to  be  expanded  by  the  remote  server
              according to the authz rules; see slapd.conf(5) for details.  In
              the latter case, whether or not the dn: prefix is  present,  the
              string must pass DN validation and normalization.

              The  default  mode  is legacy, which implies that the proxy will
              either perform a simple bind as the authcDN or a  SASL  bind  as
              the  authcID  and  assert  the  client's identity when it is not
              anonymous.  The other modes imply that  the  proxy  will  always
              either  perform  a  simple bind as the authcDN or a SASL bind as
              the authcID, unless restricted by idassert-authzFrom rules  (see
              below),  in  which  case the operation will fail; eventually, it
              will assert some other  identity  according  to  <mode>.   Other
              identity   assertion   modes   are  anonymous  and  self,  which
              respectively mean that the empty or the client's  identity  will
              be  asserted;  none, which means that no proxyAuthz control will
              be used,  so  the  authcDN  or  the  authcID  identity  will  be
              asserted.   For all modes that require the use of the proxyAuthz
              control, on the remote  server  the  proxy  identity  must  have
              appropriate authzTo permissions, or the asserted identities must
              have appropriate authzFrom permissions.  Note, however, that the
              ID   assertion  feature  is  mostly  useful  when  the  asserted
              identities do not exist on the remote server.

              Flags can be

              override,[non-]prescriptive,proxy-authz-[non-]critical

              When the override flag is used, identity assertion  takes  place
              even  when  the  database is authorizing for the identity of the
              client, i.e. after binding with the provided identity, and  thus
              authenticating  it,  the  proxy  performs the identity assertion
              using the configured identity and authentication method.

              When the prescriptive flag is  used  (the  default),  operations
              fail with inappropriateAuthentication for those identities whose
              assertion is not allowed by the idassert-authzFrom patterns.  If
              the  non-prescriptive  flag  is  used,  operations are performed
              anonymously for those identities whose assertion is not  allowed
              by the idassert-authzFrom patterns.

              When  the  proxy-authz-non-critical  flag is used (the default),
              the proxyAuthz control is not marked as critical,  in  violation
              of RFC 4370.  Use of proxy-authz-critical is recommended.

              The  TLS  settings  default  to  the  same as the main slapd TLS
              settings, except for tls_reqcert which defaults to "demand".

              The identity associated to  this  directive  is  also  used  for
              privileged  operations  whenever  idassert-bind  is  defined and
              acl-bind is not.  See acl-bind for details.

              This  directive  obsoletes  idassert-authcDN,   idassert-passwd,
              idassert-mode, and idassert-method.


       idassert-passthru <authz-regexp>
              if  defined,  selects  what local identities bypass the identity
              assertion feature.  Those identities need to  be  known  by  the
              remote  host.   The  string  <authz-regexp>  follows  the  rules
              defined for the authzFrom attribute.  See slapd.conf(5), section
              related  to  authz-policy,  for  details  on  the syntax of this
              field.



       idle-timeout <time>
              This directive causes a  cached  connection  to  be  dropped  an
              recreated after it has been idle for the specified time.


       keepalive <idle>:<probes>:<interval>
              The  keepalive  parameter  sets  the values of idle, probes, and
              interval used to check whether a socket is alive;  idle  is  the
              number  of  seconds a connection needs to remain idle before TCP
              starts sending keepalive probes; probes is the maximum number of
              keepalive probes TCP should send before dropping the connection;
              interval is interval in  seconds  between  individual  keepalive
              probes.   Only  some  systems support the customization of these
              values;  the  keepalive  parameter  is  ignored  otherwise,  and
              system-wide settings are used.


       network-timeout <time>
              Sets  the  network  timeout  value after which poll(2)/select(2)
              following a connect(2) returns in  case  of  no  activity.   The
              value   is   in   seconds,  and  it  can  be  specified  as  for
              idle-timeout.


       norefs <NO|yes>
              If yes, do not return search reference responses.   By  default,
              they are returned unless request is LDAPv2.


       omit-unknown-schema <NO|yes>
              If  yes,  do not return objectClasses or attributes that are not
              known to the local server.  The default is to return all  schema
              elements.


       noundeffilter <NO|yes>
              If  yes,  return  success  instead  of  searching if a filter is
              undefined or  contains  undefined  portions.   By  default,  the
              search  is  propagated  after  replacing undefined portions with
              (!(objectClass=*)), which corresponds to the empty result set.


       onerr {CONTINUE|stop}
              This directive allows one to select  the  behavior  in  case  an
              error  is  returned  by  the remote server during a search.  The
              default, continue, consists in returning success.  If the  value
              is set to stop, the error is returned to the client.


       protocol-version {0,2,3}
              This  directive  indicates what protocol version must be used to
              contact the remote server.  If set to 0 (the default), the proxy
              uses the same protocol version used by the client, otherwise the
              requested    protocol    is    used.     The    proxy    returns
              unwillingToPerform if an operation that is incompatible with the
              requested protocol is attempted.


       proxy-whoami {NO|yes}
              Turns on proxying of the  WhoAmI  extended  operation.  If  this
              option  is given, back-ldap will replace slapd's original WhoAmI
              routine with its own. On slapd sessions that were  authenticated
              by back-ldap, the WhoAmI request will be forwarded to the remote
              LDAP server. Other sessions will be handled by the local  slapd,
              as  before.  This  option  is  mainly useful in conjunction with
              Proxy Authorization.


       quarantine <interval>,<num>[;<interval>,<num>[...]]
              Turns on quarantine of URIs that returned  LDAP_UNAVAILABLE,  so
              that  an  attempt  to  reconnect  only occurs at given intervals
              instead of any time a client requests an operation.  The pattern
              is:  retry  only  after  at least interval seconds elapsed since
              last attempt, for exactly num times; then use the next  pattern.
              If  num  for  the  last  pattern  is  "+",  it  retries forever;
              otherwise, no more retries occur.  The process can be  restarted
              by resetting the olcDbQuarantine attribute of the database entry
              in the configuration backend.


       rebind-as-user {NO|yes}
              If this option is  given,  the  client's  bind  credentials  are
              remembered  for  rebinds,  when  trying to re-establish a broken
              connection, or when chasing a referral,  if  chase-referrals  is
              set to yes.


       session-tracking-request {NO|yes}
              Adds session tracking control for all requests.  The client's IP
              and hostname, and the identity associated to  each  request,  if
              known, are sent to the remote server for informational purposes.
              This directive is incompatible with setting protocol-version  to
              2.


       single-conn {NO|yes}
              Discards current cached connection when the client rebinds.


       t-f-support {NO|yes|discover}
              enable  if  the remote server supports absolute filters (see RFC
              4526 for details).  If set to discover, support is  detected  by
              reading the remote server's root DSE.


       timeout [<op>=]<val> [...]
              This   directive  allows  one  to  set  per-operation  timeouts.
              Operations can be

              <op> ::= bind, add, delete, modrdn, modify, compare, search

              The overall duration  of  the  search  operation  is  controlled
              either  by  the  timelimit  parameter or by server-side enforced
              time limits (see  timelimit  and  limits  in  slapd.conf(5)  for
              details).   This  timeout parameter controls how long the target
              can be irresponsive before the operation is aborted.  Timeout is
              meaningless  for  the  remaining operations, unbind and abandon,
              which do not imply any response, while it is not yet implemented
              in  currently supported extended operations.  If no operation is
              specified, the timeout val affects all supported operations.

              Note: if the timelimit is exceeded, the operation  is  cancelled
              (according  to  the  cancel  directive);  the  protocol does not
              provide any means to rollback operations, so the client will not
              be  notified  about  the  result  of  the  operation,  which may
              eventually succeeded or not.  In case the  timeout  is  exceeded
              during  a bind operation, the connection is destroyed, according
              to RFC4511.

              Note: in some cases, this backend may issue binds prior to other
              operations  (e.g.  to  bind  anonymously or with some prescribed
              identity according to the  idassert-bind  directive).   In  this
              case,  the timeout of the operation that resulted in the bind is
              used.


       tls        {[try-]start|[try-]propagate|ldaps}        [tls_cert=<file>]
              [tls_key=<file>]    [tls_cacert=<file>]   [tls_cacertdir=<path>]
              [tls_reqcert=never|allow|try|demand]
              [tls_cipher_suite=<ciphers>] [tls_crlcheck=none|peer|all]
              Specify the use of TLS when a regular connection is initialized.
              The StartTLS extended operation will  be  used  unless  the  URI
              directive protocol scheme is ldaps://. In that case this keyword
              may only be set to "ldaps" and the StartTLS operation  will  not
              be  used.   propagate  issues the StartTLS operation only if the
              original connection did.  The try- prefix instructs the proxy to
              continue operations if the StartTLS operation failed; its use is
              not recommended.

              The TLS settings default to the  same  as  the  main  slapd  TLS
              settings, except for tls_reqcert which defaults to "demand".


       use-temporary-conn {NO|yes}
              when   set  to  yes,  create  a  temporary  connection  whenever
              competing with other threads for a shared one;  otherwise,  wait
              until the shared connection is available.


BACKWARD COMPATIBILITY
       The  LDAP  backend  has  been heavily reworked between releases 2.2 and
       2.3, and subsequently between 2.3 and 2.4.  As a side-effect,  some  of
       the traditional directives have been deprecated and should be no longer
       used, as they might disappear in future releases.


       acl-authcDN <administrative DN for access control purposes>
              Formerly known as the binddn, it is the DN that is used to query
              the  target server for acl checking; it is supposed to have read
              access on the target server to attributes used on the proxy  for
              acl checking.  There is no risk of giving away such values; they
              are only used to check permissions.

              The acl-authcDN identity is by no means implicitly used  by  the
              proxy  when  the  client  connects  anonymously.  The idassert-*
              feature can be used (at own risk) for that purpose instead.

              This directive is obsoleted by the binddn arg of  acl-bind  when
              bindmethod=simple, and will be dismissed in the future.


       acl-passwd <password>
              Formerly  known  as the bindpw, it is the password used with the
              above acl-authcDN directive.  This directive is obsoleted by the
              credentials  arg of acl-bind when bindmethod=simple, and will be
              dismissed in the future.


       idassert-authcDN <administrative DN for proxyAuthz purposes>
              DN which is used to  propagate  the  client's  identity  to  the
              target  by  means of the proxyAuthz control when the client does
              not belong to the DIT fragment that is being  proxied  by  back-
              ldap.   This  directive  is  obsoleted  by  the  binddn  arg  of
              idassert-bind when bindmethod=simple, and will be  dismissed  in
              the future.


       idassert-passwd <password>
              Password  used  with the idassert-authcDN above.  This directive
              is obsoleted by  the  crendentials  arg  of  idassert-bind  when
              bindmethod=simple, and will be dismissed in the future.


       idassert-mode <mode> [<flags>]
              defines what type of identity assertion is used.  This directive
              is obsoleted by the mode  arg  of  idassert-bind,  and  will  be
              dismissed in the future.


       idassert-method <method> [<saslargs>]
              This   directive   is   obsoleted   by  the  bindmethod  arg  of
              idassert-bind, and will be dismissed in the future.


       port <port>
              this directive is no longer supported.  Use the uri directive as
              described above.


       server <hostname[:port]>
              this directive is no longer supported.  Use the uri directive as
              described above.


       suffixmassage, map, rewrite*
              These directives are no longer  supported  by  back-ldap;  their
              functionality is now delegated to the rwm overlay.  Essentially,
              add a statement

              overlay rwm

              first, and prefix all rewrite/map statements with rwm- to obtain
              the original behavior.  See slapo-rwm(5) for details.


ACCESS CONTROL
       The  ldap  backend  does  not  honor  all ACL semantics as described in
       slapd.access(5).  In general,  access  checking  is  delegated  to  the
       remote  server(s).  Only read (=r) access to the entry pseudo-attribute
       and to the other attribute values of the entries returned by the search
       operation is honored, which is performed by the frontend.


OVERLAYS
       The  LDAP  backend  provides  basic  proxying  functionalities  to many
       overlays.  The chain overlay,  described  in  slapo-chain(5),  and  the
       translucent  overlay,  described  in  slapo-translucent(5),  deserve  a
       special mention.

       Conversely, there are many overlays that are best used  in  conjunction
       with  the  LDAP backend.  The proxycache overlay allows caching of LDAP
       search requests (queries) in a local database.  See slapo-pcache(5) for
       details.  The rwm overlay provides DN rewrite and attribute/objectClass
       mapping capabilities to the underlying database.  See slapo-rwm(5)  for
       details.


FILES
       /etc/openldap/slapd.conf
              default slapd configuration file


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+-------------------------------+
       |ATTRIBUTE TYPE |       ATTRIBUTE VALUE         |
       +---------------+-------------------------------+
       |Availability   | service/network/ldap/openldap |
       +---------------+-------------------------------+
       |Stability      | Pass-through uncommitted      |
       +---------------+-------------------------------+
SEE ALSO
       slapd.conf(5),    slapd-config(5),    slapd-meta(5),    slapo-chain(5),
       slapo-pcache(5), slapo-rwm(5), slapo-translucent(5), slapd(8), ldap(3).

AUTHOR
       Howard Chu, with enhancements by Pierangelo Masarati



NOTES
       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source                was                downloaded                from
       ftp://ftp.openldap.org/pub/OpenLDAP/openldap-
       release/openldap-2.4.46.tgz

       Further information about this software can be found on the open source
       community website at http://www.openldap.org/.



OpenLDAP 2.4.46                   2018/03/22                SLAPD-LDAP(5oldap)