How do I configure Reverse Group Membership Maintenance on an openldap server? (memberOf)
- by emills
I am currently working on integrating LDAP authentication into a system and I would like to restrict access based on LDAP group. The only way to do this is via a search filter and therefore I believe my only option to be the use of the "memberOf" attribute in my search filter. It is my understanding that the "memberOf" attribute is an operational attribute which can be created by the server for me anytime a new "member" attribute is created for any "groupOfNames" entry on the server.
My main goal is to be able to add a "member" attribute to an existing "groupOfNames" entry and have a matching "memberOf" attribute be added to the DN I provide.
What I have managed to achieve so far:
I'm still pretty new to LDAP administration but based on what I found in the openldap admin's guide, it looks like Reverse Group Membership Maintence aka "memberof overlay" would achieve exactly the effect I am looking for.
My server is currently running a package installation (slapd on ubuntu) of openldap 2.4.15 which uses "cn=config" style runtime configuration. Most of the examples I have found still reference the older "slapd.conf" method of static configuration and I have tried my best to adapt the configurations to the new directory based model.
I have added the following entries to enable the memberof overlay module:
Enable the module with olcModuleLoad
cn=config/cn\=module\{0\}.ldif
dn: cn=module{0}
objectClass: olcModuleList
cn: module{0}
olcModulePath: /usr/lib/ldap
olcModuleLoad: {0}back_hdb
olcModuleLoad: {1}memberof.la
structuralObjectClass: olcModuleList
entryUUID: a410ce98-3fdf-102e-82cf-59ccb6b4d60d
creatorsName: cn=config
createTimestamp: 20090927183056Z
entryCSN: 20091009174548.503911Z#000000#000#000000
modifiersName: cn=admin,cn=config
modifyTimestamp: 20091009174548Z
Enabled the overlay for the database and allowed it to use it's default settings (groupOfNames,member,memberOf,etc)
cn=config/olcDatabase={1}hdb/olcOverlay\=\{0\}memberof
dn: olcOverlay={0}memberof
objectClass: olcMemberOf
objectClass: olcOverlayConfig
objectClass: olcConfig
objectClass: top
olcOverlay: {0}memberof
structuralObjectClass: olcMemberOf
entryUUID: 6d599084-490c-102e-80f6-f1a5d50be388
creatorsName: cn=admin,cn=config
createTimestamp: 20091009104412Z
olcMemberOfRefInt: TRUE
entryCSN: 20091009173500.139380Z#000000#000#000000
modifiersName: cn=admin,cn=config
modifyTimestamp: 20091009173500Z
My current result:
By using the above configuration, I am able to add a NEW "groupOfNames" with any number of "member" entries and have all the involved DNs updated with a "memberOf" attribute. This is part of the behavior I would expect. While I believe the following should have been accomplished with the memberof overlay, I still do not know how to do the following and I would gladly welcome any advice:
Add a "member" attribute to an EXISTING "groupOfNames" and have a corresponding "memberOf" attribute be created automatically.
Remove a "member" attribute and have the corresponding "memberOf" attribute" be removed automatically.
