1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
|
Configuring Kerberos with OpenLDAP back-end
===========================================
1. Set up SSL on the OpenLDAP server and client to ensure secure
communication when the KDC service and LDAP server are on different
machines. ``ldapi://`` can be used if the LDAP server and KDC
service are running on the same machine.
A. Setting up SSL on the OpenLDAP server:
i) Get a CA certificate using OpenSSL tools
ii) Configure OpenLDAP server for using SSL/TLS
For the latter, you need to specify the location of CA
certificate location in *slapd.conf* file.
Refer to the following link for more information:
http://www.openldap.org/doc/admin23/tls.html
B. Setting up SSL on OpenLDAP client:
i) For the KDC and Admin Server, you need to do the client-side
configuration in ldap.conf. For example::
TLS_CACERT /etc/openldap/certs/cacert.pem
2. Include the Kerberos schema file (kerberos.schema) in the
configuration file (slapd.conf) on the LDAP Server, by providing
the location where it is stored::
include /etc/openldap/schema/kerberos.schema
3. Choose DNs for the :ref:`krb5kdc(8)` and :ref:`kadmind(8)` servers
to bind to the LDAP server, and create them if necessary. These DNs
will be specified with the **ldap_kdc_dn** and **ldap_kadmind_dn**
directives in :ref:`kdc.conf(5)`; their passwords can be stashed
with "``kdb5_ldap_util stashsrvpw``" and the resulting file
specified with the **ldap_service_password_file** directive.
4. Choose a DN for the global Kerberos container entry (but do not
create the entry at this time). This DN will be specified with the
**ldap_kerberos_container_dn** directive in :ref:`kdc.conf(5)`.
Realm container entries will be created underneath this DN.
Principal entries may exist either underneath the realm container
(the default) or in separate trees referenced from the realm
container.
5. Configure the LDAP server ACLs to enable the KDC and kadmin server
DNs to read and write the Kerberos data.
Sample access control information::
access to dn.base=""
by * read
access to dn.base="cn=Subschema"
by * read
access to attrs=userPassword,userPKCS12
by self write
by * auth
access to attrs=shadowLastChange
by self write
by * read
# Providing access to realm container
access to dn.subtree= "cn=EXAMPLE.COM,cn=krbcontainer,dc=example,dc=com"
by dn.exact="cn=kdc-service,dc=example,dc=com" read
by dn.exact="cn=adm-service,dc=example,dc=com" write
by * none
# Providing access to principals, if not underneath realm container
access to dn.subtree= "ou=users,dc=example,dc=com"
by dn.exact="cn=kdc-service,dc=example,dc=com" read
by dn.exact="cn=adm-service,dc=example,dc=com" write
by * none
access to *
by * read
If the locations of the container and principals or the DNs of
the service objects for a realm are changed then this
information should be updated.
6. Start the LDAP server as follows::
slapd -h "ldapi:/// ldaps:///"
7. Modify the :ref:`kdc.conf(5)` file to include LDAP specific items
listed below::
realms
database_module
dbmodules
db_library
db_module_dir
ldap_kdc_dn
ldap_kadmind_dn
ldap_service_password_file
ldap_servers
ldap_conns_per_server
8. Create the realm using :ref:`kdb5_ldap_util(8)` (see
:ref:`ldap_create_realm`)::
kdb5_ldap_util -D cn=admin,dc=example,dc=com create -subtrees ou=users,dc=example,dc=com -r EXAMPLE.COM -s
Use the **-subtrees** option if the principals are to exist in a
separate subtree from the realm container. Before executing the
command, make sure that the subtree mentioned above
``(ou=users,dc=example,dc=com)`` exists. If the principals will
exist underneath the realm container, omit the **-subtrees** option
and do not worry about creating the principal subtree.
For more information, refer to the section :ref:`ops_on_ldap`.
The realm object is created under the
**ldap_kerberos_container_dn** specified in the configuration file.
This operation will also create the Kerberos container, if not
present already. This will be used to store information related to
all realms.
9. Stash the password of the service object used by the KDC and
Administration service to bind to the LDAP server using the
:ref:`kdb5_ldap_util(8)` **stashsrvpw** command (see
:ref:`stash_ldap`). The object DN should be the same as
**ldap_kdc_dn** and **ldap_kadmind_dn** values specified in the
:ref:`kdc.conf(5)` file::
kdb5_ldap_util -D cn=admin,dc=example,dc=com stashsrvpw -f /etc/kerberos/service.keyfile cn=krbadmin,dc=example,dc=com
10. Add ``krbPrincipalName`` to the indexes in slapd.conf to speed up
the access.
With the LDAP back end it is possible to provide aliases for principal
entries. Currently we provide no mechanism provided for creating
aliases, so it must be done by direct manipulation of the LDAP
entries.
An entry with aliases contains multiple values of the
*krbPrincipalName* attribute. Since LDAP attribute values are not
ordered, it is necessary to specify which principal name is canonical,
by using the *krbCanonicalName* attribute. Therefore, to create
aliases for an entry, first set the *krbCanonicalName* attribute of
the entry to the canonical principal name (which should be identical
to the pre-existing *krbPrincipalName* value), and then add additional
*krbPrincipalName* attributes for the aliases.
Principal aliases are only returned by the KDC when the client
requests canonicalization. Canonicalization is normally requested for
service principals; for client principals, an explicit flag is often
required (e.g., ``kinit -C``) and canonicalization is only performed
for initial ticket requests.
.. seealso:: :ref:`ldap_be_ubuntu`
|
