trusty (5) slapd-relay.5.gz

Provided by: slapd_2.4.31-1+nmu2ubuntu8.5_amd64 bug

NAME

       slapd-relay - relay backend to slapd

SYNOPSIS

       /etc/ldap/slapd.conf

DESCRIPTION

       The  primary purpose of this slapd(8) backend is to map a naming context defined in a database running in
       the  same  slapd(8)  instance  into  a  virtual  naming  context,  with  attributeType  and   objectClass
       manipulation, if required.  It requires the slapo-rwm(5) overlay.

       This backend and the above mentioned overlay are experimental.

CONFIGURATION

       The  following  slapd.conf  directives  apply to the relay backend database.  That is, they must follow a
       "database relay" line and come before any subsequent  "backend"  or  "database"  lines.   Other  database
       options are described in the slapd.conf(5) manual page; only the suffix directive is allowed by the relay
       backend.

       relay <real naming context>
              The naming context of the database that is presented under a virtual naming context.  The presence
              of  this  directive  implies  that  one  specific  database,  i.e. the one serving the real naming
              context, will be presented under a virtual naming context.

MASSAGING

       The relay database does not automatically rewrite the naming context of requests and responses.  For this
       purpose,  the  slapo-rwm(5)  overlay  must  be  explicitly  instantiated,  and configured as appropriate.
       Usually, the rwm-suffixmassage directive suffices if only naming context rewriting is required.

ACCESS RULES

       One important issue is that access rules are based on the identity  that  issued  the  operation.   After
       massaging  from  the  virtual to the real naming context, the frontend sees the operation as performed by
       the identity in the real naming context.  Moreover, since back-relay bypasses the real database  frontend
       operations  by short-circuiting operations through the internal backend API, the original database access
       rules do not apply but in selected cases, i.e. when the backend itself  applies  access  control.   As  a
       consequence,  the  instances of the relay database must provide own access rules that are consistent with
       those of the original database, possibly adding further specific restrictions.  So, access rules  in  the
       relay  database  must  refer  to  identities  in  the  real naming context.  Examples are reported in the
       EXAMPLES section.

SCENARIOS

       If no relay directive is given, the relay database does not refer to any specific database, but the  most
       appropriate one is looked-up after rewriting the request DN for the operation that is being handled.

       This  allows  to  write carefully crafted rewrite rules that cause some of the requests to be directed to
       one database, and some to another; e.g., authentication can be mapped to one database,  and  searches  to
       another, or different target databases can be selected based on the DN of the request, and so.

       Another  possibility  is to map the same operation to different databases based on details of the virtual
       naming context, e.g. groups on one database and persons on another.

EXAMPLES

       To implement a plain virtual naming context mapping that refers to a single database, use

         database                relay
         suffix                  "dc=virtual,dc=naming,dc=context"
         relay                   "dc=real,dc=naming,dc=context"
         overlay                 rwm
         rwm-suffixmassage       "dc=real,dc=naming,dc=context"

       To implement a plain virtual naming context mapping that looks  up  the  real  naming  context  for  each
       operation, use

         database                relay
         suffix                  "dc=virtual,dc=naming,dc=context"
         overlay                 rwm
         rwm-suffixmassage       "dc=real,dc=naming,dc=context"

       This  is useful, for instance, to relay different databases that share the terminal portion of the naming
       context (the one that is rewritten).

       To implement the old-fashioned suffixalias, e.g. mapping the virtual to the real naming context, but  not
       the results back from the real to the virtual naming context, use

         database                relay
         suffix                  "dc=virtual,dc=naming,dc=context"
         relay                   "dc=real,dc=naming,dc=context"
         overlay                 rwm
         rwm-rewriteEngine       on
         rwm-rewriteContext      default
         rwm-rewriteRule         "dc=virtual,dc=naming,dc=context"
                                 "dc=real,dc=naming,dc=context" ":@"
         rwm-rewriteContext      searchFilter
         rwm-rewriteContext      searchEntryDN
         rwm-rewriteContext      searchAttrDN
         rwm-rewriteContext      matchedDN

       Note  that the slapo-rwm(5) overlay is instantiated, but the rewrite rules are written explicitly, rather
       than automatically as with the rwm-suffixmassage statement, to map all the virtual to real naming context
       data flow, but none of the real to virtual.

       Access rules:

         database                bdb
         suffix                  "dc=example,dc=com"
         # skip...
         access to dn.subtree="dc=example,dc=com"
                 by dn.exact="cn=Supervisor,dc=example,dc=com" write
                 by * read

         database                relay
         suffix                  "o=Example,c=US"
         relay                   "dc=example,dc=com"
         overlay                 rwm
         rwm-suffixmassage       "dc=example,dc=com"
         # skip ...
         access to dn.subtree="o=Example,c=US"
                 by dn.exact="cn=Supervisor,dc=example,dc=com" write
                 by dn.exact="cn=Relay Supervisor,dc=example,dc=com" write
                 by * read

       Note  that,  in  both  databases,  the identities (the <who> clause) are in the real naming context, i.e.
       `dc=example,dc=com', while the targets (the <what> clause) are in the real  and  in  the  virtual  naming
       context, respectively.

ACCESS CONTROL

       The  relay  backend  does not honor any of the access control semantics described in slapd.access(5); all
       access control is delegated to the relayed database(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.

FILES

       /etc/ldap/slapd.conf
              default slapd configuration file

SEE ALSO

       slapd.conf(5), slapd-config(5), slapo-rwm(5), slapd(8).