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1 .TH SLAPO-CHAIN 5 "2008/07/16" "OpenLDAP 2.4.11"
2 .\" Copyright 1998-2008 The OpenLDAP Foundation, All Rights Reserved.
3 .\" Copying restrictions apply. See the COPYRIGHT file.
4 .\" $OpenLDAP: pkg/ldap/doc/man/man5/slapo-chain.5,v 1.10.2.4 2008/02/11 23:26:40 kurt Exp $
5 .SH NAME
6 slapo-chain \- chain overlay to slapd
7 .SH SYNOPSIS
8 /etc/openldap/slapd.conf
9 .SH DESCRIPTION
10 The
11 .B chain
12 overlay to
13 .BR slapd (8)
14 allows automatic referral chasing.
15 Any time a referral is returned (except for bind operations),
16 it is chased by using an instance of the ldap backend.
17 If operations are performed with an identity (i.e. after a bind),
18 that identity can be asserted while chasing the referrals
19 by means of the \fIidentity assertion\fP feature of back-ldap
20 (see
21 .BR slapd-ldap (5)
22 for details), which is essentially based on the
23 .B proxied authorization
24 control [RFC 4370].
25 Referral chasing can be controlled by the client by issuing the
26 \fBchaining\fP control
27 (see \fIdraft-sermersheim-ldap-chaining\fP for details.)
29 .LP
30 The config directives that are specific to the
31 .B chain
32 overlay are prefixed by
33 .BR chain\- ,
34 to avoid potential conflicts with directives specific to the underlying
35 database or to other stacked overlays.
37 .LP
38 There are very few chain overlay specific directives; however, directives
39 related to the instances of the \fIldap\fP backend that may be implicitly
40 instantiated by the overlay may assume a special meaning when used
41 in conjunction with this overlay. They are described in
42 .BR slapd-ldap (5),
43 and they also need to be prefixed by
44 .BR chain\- .
45 .TP
46 .B overlay chain
47 This directive adds the chain overlay to the current backend.
48 The chain overlay may be used with any backend, but it is mainly
49 intended for use with local storage backends that may return referrals.
50 It is useless in conjunction with the \fIslapd-ldap\fP and \fIslapd-meta\fP
51 backends because they already exploit the libldap specific referral chase
52 feature.
53 [Note: this may change in the future, as the \fBldap\fP(5) and
54 \fBmeta\fP(5) backends might no longer chase referrals on their own.]
55 .TP
56 .B chain-cache-uri {FALSE|true}
57 This directive instructs the \fIchain\fP overlay to cache
58 connections to URIs parsed out of referrals that are not predefined,
59 to be reused for later chaining.
60 These URIs inherit the properties configured for the underlying
61 \fBslapd-ldap\fP(5) before any occurrence of the \fBchain-uri\fP
62 directive; basically, they are chained anonymously.
63 .TP
64 .B chain-chaining [resolve=<r>] [continuation=<c>] [critical]
65 This directive enables the \fIchaining\fP control
66 (see \fIdraft-sermersheim-ldap-chaining\fP for details)
67 with the desired resolve and continuation behaviors and criticality.
68 The \fBresolve\fP parameter refers to the behavior while discovering
69 a resource, namely when accessing the object indicated by the request DN;
70 the \fBcontinuation\fP parameter refers to the behavior while handling
71 intermediate responses, which is mostly significant for the search
72 operation, but may affect extended operations that return intermediate
73 responses.
74 The values \fBr\fP and \fBc\fP can be any of
75 .BR chainingPreferred ,
76 .BR chainingRequired ,
77 .BR referralsPreferred ,
78 .BR referralsRequired .
79 If the \fBcritical\fP flag affects the control criticality if provided.
80 [This control is experimental and its support may change in the future.]
81 .TP
82 .B chain-max-depth <n>
83 In case a referral is returned during referral chasing, further chasing
84 occurs at most \fB<n>\fP levels deep. Set to \fB1\fP (the default)
85 to disable further referral chasing.
86 .TP
87 .B chain-return-error {FALSE|true}
88 In case referral chasing fails, the real error is returned instead
89 of the original referral. In case multiple referral URIs are present,
90 only the first error is returned. This behavior may not be always
91 appropriate nor desirable, since failures in referral chasing might be
92 better resolved by the client (e.g. when caused by distributed
93 authentication issues).
94 .TP
95 .B chain-uri <ldapuri>
96 This directive instantiates a new underlying \fIldap\fP database
97 and instructs it about which URI to contact to chase referrals.
98 As opposed to what stated in \fBslapd-ldap\fP(5), only one URI
99 can appear after this directive; all subsequent \fBslapd-ldap\fP(5)
100 directives prefixed by \fBchain-\fP refer to this specific instance
101 of a remote server.
102 .LP
104 Directives for configuring the underlying ldap database may also
105 be required, as shown in this example:
106 .LP
107 .RS
108 .nf
109 overlay chain
110 chain-rebind-as-user FALSE
112 chain-uri "ldap://ldap1.example.com"
113 chain-rebind-as-user TRUE
114 chain-idassert-bind bindmethod="simple"
115 binddn="cn=Auth,dc=example,dc=com"
116 credentials="secret"
117 mode="self"
119 chain-uri "ldap://ldap2.example.com"
120 chain-idassert-bind bindmethod="simple"
121 binddn="cn=Auth,dc=example,dc=com"
122 credentials="secret"
123 mode="none"
125 .fi
126 .RE
127 .LP
128 Any valid directives for the ldap database may be used; see
129 .BR slapd-ldap (5)
130 for details.
131 Multiple occurrences of the \fBchain-uri\fP directive may appear,
132 to define multiple "trusted" URIs where operations with
133 \fIidentity assertion\fP are chained.
134 All URIs not listed in the configuration are chained anonymously.
135 All \fBslapd-ldap\fP(5) directives appearing before the first
136 occurrence of \fBchain-uri\fP are inherited by all URIs,
137 unless specifically overridden inside each URI configuration.
138 .SH FILES
139 .TP
140 /etc/openldap/slapd.conf
141 default slapd configuration file
142 .SH SEE ALSO
143 .BR slapd.conf (5),
144 .BR slapd\-ldap (5),
145 .BR slapd (8).
146 .SH AUTHOR
147 Originally implemented by Howard Chu; extended by Pierangelo Masarati.