How to set up LDAP users and groups

powersj · August 18, 2023, 12:56pm

Once you have a working LDAP server, you will need to install libraries on the client that know how and when to contact it. On Ubuntu, this was traditionally done by installing the libnss-ldap package, but nowadays you should use the System Security Services Daemon (SSSD). To find out how to use LDAP with SSSD, refer to our SSSD and LDAP guide.

User and group management - `ldapscripts`

A common use case for an LDAP server is to store Unix user and group information in the directory. There are many tools out there, and big deployments will usually develop their own. However, as a quick and easy way to get started storing user and group information in OpenLDAP, you can use the ldapscripts package.

Install ldapscripts

You can install ldapscripts by running the following command:

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'

Notes:

Adjust SERVER and related SUFFIX options to suit your directory structure.

Here, we are forcing use of START_TLS (-ZZ parameter). Refer to LDAP with TLS to learn how to set up the server 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.

Manage users and groups with ldapscripts

Here are some brief examples you can use to manage users and groups using ldapscripts.

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” as well.

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 that 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.

Manage user attributes with `ldapmodifyuser`

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”.

`ldapscripts` templates

A nice feature of ldapscripts is the template system. Templates allow you to customise the attributes of user, group, and machine objects. For example, to enable the user template, edit /etc/ldapscripts/ldapscripts.conf by changing:

UTEMPLATE="/etc/ldapscripts/ldapadduser.template"

There are sample templates in the /usr/share/doc/ldapscripts/examples directory. Copy or rename the ldapadduser.template.sample file to /etc/ldapscripts/ldapadduser.template:

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 of them:

dpkg -L ldapscripts | grep /usr/sbin

Next steps

Now that you know how to set up and modify users and groups, you may wish to learn more about how access control works. If you’re already familiar with this topic, it’s a good idea to secure your LDAP communication by setting up Transport Layer Security (TLS).