1SLAPD-RELAY(5) File Formats Manual SLAPD-RELAY(5)
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6 slapd-relay - relay backend to slapd
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9 /etc/openldap/slapd.conf
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12 The primary purpose of this slapd(8) backend is to map a naming context
13 defined in a database running in the same slapd(8) instance into a vir‐
14 tual naming context, with attributeType and objectClass manipulation,
15 if required. It requires the slapo-rwm(5) overlay.
16 This backend and the above mentioned overlay are experimental.
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20 The following slapd.conf directives apply to the relay backend data‐
21 base. That is, they must follow a "database relay" line and come be‐
22 fore any subsequent "backend" or "database" lines. Other database op‐
23 tions are described in the slapd.conf(5) manual page; only the suffix
24 directive is allowed by the relay backend.
25 relay <real naming context>
27 The naming context of the database that is presented under a
28 virtual naming context. The presence of this directive implies
29 that one specific database, i.e. the one serving the real naming
30 context, will be presented under a virtual naming context.
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34 The relay database does not automatically rewrite the naming context of
35 requests and responses. For this purpose, the slapo-rwm(5) overlay
36 must be explicitly instantiated, and configured as appropriate. Usu‐
37 ally, the rwm-suffixmassage directive suffices if only naming context
38 rewriting is required.
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42 One important issue is that access rules are based on the identity that
43 issued the operation. After massaging from the virtual to the real
44 naming context, the frontend sees the operation as performed by the
45 identity in the real naming context. Moreover, since back-relay by‐
46 passes the real database frontend operations by short-circuiting opera‐
47 tions through the internal backend API, the original database access
48 rules do not apply but in selected cases, i.e. when the backend itself
49 applies access control. As a consequence, the instances of the relay
50 database must provide own access rules that are consistent with those
51 of the original database, possibly adding further specific restric‐
52 tions. So, access rules in the relay database must refer to identities
53 in the real naming context. Examples are reported in the EXAMPLES sec‐
54 tion.
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58 If no relay directive is given, the relay database does not refer to
59 any specific database, but the most appropriate one is looked-up after
60 rewriting the request DN for the operation that is being handled.
61 This allows one to write carefully crafted rewrite rules that cause
63 some of the requests to be directed to one database, and some to an‐
64 other; e.g., authentication can be mapped to one database, and searches
65 to another, or different target databases can be selected based on the
66 DN of the request, and so.
67 Another possibility is to map the same operation to different databases
69 based on details of the virtual naming context, e.g. groups on one
70 database and persons on another.
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73 To implement a plain virtual naming context mapping that refers to a
74 single database, use
75 database relay
77 suffix "dc=virtual,dc=naming,dc=context"
78 relay "dc=real,dc=naming,dc=context"
79 overlay rwm
80 rwm-suffixmassage "dc=real,dc=naming,dc=context"
81 To implement a plain virtual naming context mapping that looks up the
83 real naming context for each operation, use
84 database relay
86 suffix "dc=virtual,dc=naming,dc=context"
87 overlay rwm
88 rwm-suffixmassage "dc=real,dc=naming,dc=context"
89 This is useful, for instance, to relay different databases that share
91 the terminal portion of the naming context (the one that is rewritten).
92 To implement the old-fashioned suffixalias, e.g. mapping the virtual to
94 the real naming context, but not the results back from the real to the
95 virtual naming context, use
96 database relay
98 suffix "dc=virtual,dc=naming,dc=context"
99 relay "dc=real,dc=naming,dc=context"
100 overlay rwm
101 rwm-rewriteEngine on
102 rwm-rewriteContext default
103 rwm-rewriteRule "dc=virtual,dc=naming,dc=context"
104 "dc=real,dc=naming,dc=context" ":@"
105 rwm-rewriteContext searchFilter
106 rwm-rewriteContext searchEntryDN
107 rwm-rewriteContext searchAttrDN
108 rwm-rewriteContext matchedDN
109 Note that the slapo-rwm(5) overlay is instantiated, but the rewrite
111 rules are written explicitly, rather than automatically as with the
112 rwm-suffixmassage statement, to map all the virtual to real naming con‐
113 text data flow, but none of the real to virtual.
114 Access rules:
116 database bdb
118 suffix "dc=example,dc=com"
119 # skip...
120 access to dn.subtree="dc=example,dc=com"
121 by dn.exact="cn=Supervisor,dc=example,dc=com" write
122 by * read
123 database relay
125 suffix "o=Example,c=US"
126 relay "dc=example,dc=com"
127 overlay rwm
128 rwm-suffixmassage "dc=example,dc=com"
129 # skip ...
130 access to dn.subtree="o=Example,c=US"
131 by dn.exact="cn=Supervisor,dc=example,dc=com" write
132 by dn.exact="cn=Relay Supervisor,dc=example,dc=com" write
133 by * read
134 Note that, in both databases, the identities (the <who> clause) are in
136 the real naming context, i.e. `dc=example,dc=com', while the targets
137 (the <what> clause) are in the real and in the virtual naming context,
138 respectively.
139
141 The relay backend does not honor any of the access control semantics
142 described in slapd.access(5); all access control is delegated to the
143 relayed database(s). Only read (=r) access to the entry pseudo-attri‐
144 bute and to the other attribute values of the entries returned by the
145 search operation is honored, which is performed by the frontend.
146
148 /etc/openldap/slapd.conf
149 default slapd configuration file
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152 slapd.conf(5), slapd-config(5), slapo-rwm(5), slapd(8).
153OpenLDAP 2021/06/03 SLAPD-RELAY(5)