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Setting up an LDAP server is essential when you want centralized authentication across multiple systems. Instead of managing local users on every machine, LDAP allows you to maintain a unified directory service.

In this guide, we will install and configure OpenLDAP using the slapd service on a Linux server.

What is OpenLDAP?

OpenLDAP is an open-source implementation of the Lightweight Directory Access Protocol (LDAP). It is widely used for:

• Centralized user authentication
• Directory-based access control
• Managing user credentials across servers
• Integrating with mail servers, VPNs, and web applications

The main LDAP daemon is called slapd.

Step 1: Install OpenLDAP Packages

First, update your package list:

apt-get update

Now install the required packages:

apt-get install slapd ldap-utils migrationtools

Package Explanation

• slapd – OpenLDAP server daemon
• ldap-utils – LDAP command-line tools
• migrationtools – Tools for migrating existing accounts

During installation, you will be prompted to set:

• Administrator password
• Confirm password

Make sure to store this securely.

Step 2: Reconfigure slapd

To properly configure the LDAP server, run:

dpkg-reconfigure slapd

You will see configuration prompts. Use the following settings:

Prompt	Recommended Value
Omit OpenLDAP server configuration?	No
DNS domain name	example.local
Organization name	example.local
Administrator password	(your secure password)
Database backend	BDB
Remove database when slapd is purged?	No
Move old database?	Yes
Allow LDAPv2 protocol?	No

What These Settings Mean

• DNS domain name defines your LDAP base DN
• Organization name is used in directory structure
• BDB (Berkeley DB) is the storage backend
• LDAPv2 is disabled for security reasons

Step 3: Restart OpenLDAP Service

After configuration, restart the service:

/etc/init.d/slapd restart

Or on newer systems:

systemctl restart slapd

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Step 4: Verify LDAP is Running

Check service status:

systemctl status slapd

Test LDAP connectivity:

ldapsearch -x

If configured correctly, you should see directory information returned.

Common Issues and Troubleshooting

1️⃣ slapd Fails to Start

• Check logs:

journalctl -xe

• Verify port 389 is not blocked

2️⃣ Authentication Fails

• Confirm base DN
• Check admin password
• Verify firewall rules

3️⃣ Migration Issues

• Ensure migrationtools is properly configured
• Verify correct domain mapping

Security Best Practices

When running OpenLDAP in production:

• Enable TLS/SSL encryption
• Restrict anonymous binds
• Use strong admin passwords
• Configure firewall rules
• Regularly back up LDAP database

FAQ Section

What is slapd in OpenLDAP?

slapd is the standalone LDAP daemon that handles directory service requests.

Which port does OpenLDAP use?

By default, LDAP runs on port 389 and LDAPS runs on port 636.

Can OpenLDAP be used for centralized login?

Yes, OpenLDAP is commonly used for centralized authentication across Linux servers and applications.

If you require help, contact SupportPRO Server Admin