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NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION | MASSAGING | ACCESS RULES | SCENARIOS | EXAMPLES | ACCESS CONTROL | FILES | SEE ALSO | COLOPHON |
SLAPD-RELAY(5) File Formats Manual SLAPD-RELAY(5)
slapd-relay - relay backend to slapd
ETCDIR/slapd.conf
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.
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.
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.
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.
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 one 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.
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 mdb
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.
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.
ETCDIR/slapd.conf
default slapd configuration file
slapd.conf(5), slapd-config(5), slapo-rwm(5), slapd(8).
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COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
OpenLDAP LDVERSION RELEASEDATE SLAPD-RELAY(5)
Pages that refer to this page: slapd.backends(5), slapd-ldap(5), slapd-meta(5), slapo-rwm(5)