LDAP Workstation Authentication
Once you have a working LDAP server, you will need to install libraries on the client that will know how and when to contact it. On Ubuntu, this has been traditionally accomplished by installing the libnss-ldap package, but nowadays you should use SSSD. Please refer to Service - SSSD.
User and Group Management - ldapscripts
Another very common usage case for having an LDAP server is to store unix user and group information in the directory. There are many tools out there, but usually big deployments will have developed their own. Here we will briefly show how to use the
ldapscripts package for an easy and quick way to start storing user and group information in OpenLDAP.
Install the package:
sudo apt install ldapscripts
Then edit the file
/etc/ldapscripts/ldapscripts.conf to arrive at something similar to the following:
SERVER=ldap://ldap01.example.com LDAPBINOPTS="-ZZ" BINDDN='cn=admin,dc=example,dc=com' BINDPWDFILE="/etc/ldapscripts/ldapscripts.passwd" SUFFIX='dc=example,dc=com' GSUFFIX='ou=Groups' USUFFIX='ou=People' MSUFFIX='ou=Computers'
- Adjust SERVER and related SUFFIX options to suit your directory structure.
- Note we are forcing START_TLS usage here (-ZZ parameter), please refer to LDAP with TLS for details on how to set the server up with TLS support
Store the cn=admin password in the
/etc/ldapscripts/ldapscripts.passwd file and make sure it’s only readable by the root local user:
$ sudo chmod 400 /etc/ldapscripts/ldapscripts.passwd
The scripts are now ready to help manage your directory. Here are some examples of how to use them:
Create a new user:
sudo ldapaddgroup george sudo ldapadduser george george
This will create a group and user with name george and set the user’s primary group (gid) to george
Change a user’s password:
$ sudo ldapsetpasswd george Changing password for user uid=george,ou=People,dc=example,dc=com New Password: Retype New Password: Successfully set password for user uid=george,ou=People,dc=example,dc=com
Delete a user:
sudo ldapdeleteuser george > **Note** > > This won't delete the user's primary group, but will remove the user from supplementary ones.
Add a group:
sudo ldapaddgroup qa
Delete a group:
sudo ldapdeletegroup qa
Add a user to a group:
sudo ldapaddusertogroup george qa
You should now see a memberUid attribute for the qa group with a value of george.
Remove a user from a group:
sudo ldapdeleteuserfromgroup george qa
The memberUid attribute should now be removed from the qa group.
The ldapmodifyuser script allows you to add, remove, or replace a user’s attributes. The script uses the same syntax as the ldapmodify utility. For example:
sudo ldapmodifyuser george # About to modify the following entry : dn: uid=george,ou=People,dc=example,dc=com objectClass: account objectClass: posixAccount cn: george uid: george uidNumber: 10001 gidNumber: 10001 homeDirectory: /home/george loginShell: /bin/bash gecos: george description: User account userPassword:: e1NTSEF9eXFsTFcyWlhwWkF1eGUybVdFWHZKRzJVMjFTSG9vcHk= # Enter your modifications here, end with CTRL-D. dn: uid=george,ou=People,dc=example,dc=com replace: gecos gecos: George Carlin
The user’s gecos should now be “George Carlin”.
A nice feature of ldapscripts is the template system. Templates allow you to customize the attributes of user, group, and machine objects. For example, to enable the user template edit
There are sample templates in the
/usr/share/doc/ldapscripts/examplesdirectory. Copy or rename the
sudo cp /usr/share/doc/ldapscripts/examples/ldapadduser.template.sample \ /etc/ldapscripts/ldapadduser.template
Edit the new template to add the desired attributes. The following will create new users with an objectClass of inetOrgPerson:
dn: uid=<user>,<usuffix>,<suffix> objectClass: inetOrgPerson objectClass: posixAccount cn: <user> sn: <ask> uid: <user> uidNumber: <uid> gidNumber: <gid> homeDirectory: <home> loginShell: <shell> gecos: <user> description: User account title: Employee
Notice the <ask> option used for the sn attribute. This will make ldapadduser prompt you for its value.
There are utilities in the package that were not covered here. This command will output a list:
dpkg -L ldapscripts | grep /usr/sbin
The primary resource is the upstream documentation: www.openldap.org
Zytrax’s LDAP for Rocket Scientists; a less pedantic but comprehensive treatment of LDAP
A Ubuntu community OpenLDAP wiki page has a collection of notes
O’Reilly’s LDAP System Administration (textbook; 2003)
Packt’s Mastering OpenLDAP (textbook; 2007)