Step-by-Step Guide: Installing OpenLDAP on Ubuntu and CentOS


Understanding OpenLDAP and its Importance

OpenLDAP, or Lightweight Directory Access Protocol, is a free and open-source software that enables users to access, manage, and store directory information. In simple terms, OpenLDAP is an efficient solution for managing user accounts and groups in an organization.

It provides a centralized directory service that can be accessed by multiple applications and systems. With the growing number of online services and applications, managing user accounts in a centralized manner has become essential for organizations.

This is where OpenLDAP comes into play. It enables organizations to create directories that can be used for various purposes such as authentication, authorization, address book management, etc.

Brief Overview of the Installation Process

Installing OpenLDAP on Ubuntu or CentOS may seem like a daunting task but with the right guidance it can be achieved with ease. The installation process involves downloading necessary packages and configuring the LDAP server settings according to your organization’s needs. Once installed correctly, you can create users and groups in the LDAP directory to manage their access to various resources within your organization.

Throughout this article we will provide you with detailed step-by-step instructions for installing OpenLDAP on Ubuntu and CentOS operating systems. By following these instructions carefully you will have a fully functional OpenLDAP installation in no time!


OpenLDAP is a powerful open-source LDAP server that is used to manage directory information. To install OpenLDAP on Ubuntu and CentOS, there are certain prerequisites that need to be satisfied. In this section of the article, we will go over the list of requirements you should have and steps to ensure all prerequisites are met.

List of requirements for installing OpenLDAP on Ubuntu and CentOS

1. A server running Ubuntu or CentOS OS 2. A root access or sudo user account

3. A static IP address assigned to the server 4. Basic knowledge of Linux commands and LDAP concepts

In addition, you will also need to make sure that your system is up-to-date before beginning the installation process. Use the following command in your terminal to update your system: “`

$ sudo apt-get update && sudo apt-get upgrade -y # For Ubuntu $ sudo yum update && sudo yum upgrade -y # For CentOS “`

Steps to ensure all prerequisites are met before beginning the installation process

Before proceeding with the installation process, it is important to ensure that all prerequisites have been met: 1. Verify your operating system version: OpenLDAP can be installed on both Ubuntu and CentOS, but different versions of OpenLDAP may require specific versions of these operating systems.

– For Ubuntu: Verify that you’re running 16.04 LTS or later versions. – For CentOS: Verify that you’re running at least 7.x version.

You can verify your OS version by using the following command: “` $ lsb_release -a # For Ubuntu

$ cat /etc/centos-release # For CentOS “` 2. Set a static IP address: A static IP address ensures that your server has a reliable network connection during and after installation.

– To set a static IP address in Ubuntu, you can use the following command: “` $ sudo nano /etc/network/interfaces “`

– To set a static IP address in CentOS, you need to edit the networking configuration file: “` $ sudo nano /etc/sysconfig/network-scripts/ifcfg-[network interface name] “`

3. Create a sudo user account: It is always recommended that you create a new user with sudo privileges for security reasons. – To add a new user with sudo privileges in Ubuntu, use the following command: “`

$ adduser [username] && gpasswd -a [username] sudo “` – To add a new user with sudo privileges in CentOS, use the following command: “`

$ useradd [username] $ passwd [password]

$ visudo # Add the following line at the end of the file:

[username] ALL=(ALL) ALL “` By following these steps, you ensure that all prerequisites are met before beginning to install and configure OpenLDAP on your server running Ubuntu or CentOS.

Installing OpenLDAP on Ubuntu

Installing Necessary Packages

Before installing OpenLDAP, it’s important to ensure that all necessary packages are installed. This can be done by running the following command in the terminal:

sudo apt-get install slapd ldap-utils

This will install both the OpenLDAP server and client utilities. Once the packages have finished downloading, you will be prompted to set a password for the administrative account of OpenLDAP. Be sure to choose a secure password and remember it for future use.

Configuring LDAP Server Settings

After installing the necessary packages, it’s time to configure the LDAP server settings. This can be done through a series of prompts by running the following command in the terminal:

sudo dpkg-reconfigure slapd

The prompts will ask for information such as organization name, domain name, and base DN (Distinguished Name). It’s important to carefully consider these options as they will impact how LDAP functions within your system. Once all prompts have been completed, you can test that OpenLDAP is functioning correctly by running the command:

sudo systemctl status slapd

This should return a status of “active (running)” indicating that OpenLDAP is up and running.

Adding Users and Groups to LDAP Directory

Now that OpenLDAP is installed and configured on Ubuntu, it’s time to start adding users and groups to the directory. This can be done using tools such as ldapadd or phpldapadmin.

To add a user using ldapadd, first create an LDIF file with user details such as username, password hash, and group membership. Then run the following command in terminal:

ldapadd -x -D cn=admin,{base DN} -w -f {filename}.ldif

Be sure to replace {base DN} and {filename} with the appropriate information for your system. To add users using phpldapadmin, navigate to the web interface and login as the OpenLDAP administrator.

From there, navigate to the appropriate container in the directory tree and click “Create new entry” to add a new user. With these steps, OpenLDAP is now successfully installed on Ubuntu and ready for use in your system.

Installing OpenLDAP on CentOS

Installing Necessary Packages

Before beginning the installation of OpenLDAP on CentOS, it is important to ensure that the necessary packages are installed on the system. These packages include openldap-servers, openldap-clients, and migrationtools. To install these packages, use the yum package manager by running the following command:

“`sudo yum install openldap-servers openldap-clients migrationtools“` After installation, ensure that the LDAP server is started and set to start automatically at boot time with the following commands: “`

sudo systemctl start slapd sudo systemctl enable slapd “`

Configuring LDAP Server Settings

The next step in installing OpenLDAP on CentOS is configuring the LDAP server settings. This can be done by editing the main configuration file located at /etc/openldap/slapd.conf.

In this file, you can specify options such as base DN, root DN password, and access controls. To set up a basic configuration for testing purposes, add the following lines to the end of /etc/openldap/slapd.conf: “`

database mdb suffix “dc=my-domain,dc=com”

rootdn “cn=Manager,dc=my-domain,dc=com” rootpw {SSHA}password

directory /var/lib/ldap “` This sets up a directory at dc=my-domain.dc=com with a root user called Manager and a password of “password”.

Adding Users and Groups to LDAP Directory

Once OpenLDAP is installed and configured on CentOS, you can begin adding users and groups to your directory. The first step is to create an LDIF file containing your user or group information in a specific format.

For example, if you wanted to add a user called john with a password of “password123”, you would create an LDIF file called john.ldif with the following contents: “` dn: uid=john,dc=my-domain,dc=com

objectClass: top objectClass: account

objectClass: posixAccount objectClass: shadowAccount

cn: John Doe uid: john

uidNumber: 1000 gidNumber: 1000

homeDirectory: /home/john loginShell: /bin/bash

userPassword:: e1NTSEF9N2lybzJ1d3ZDYWl6K05HOGxXMGFDOUtyc2pSTGh5Q3M= “` To add this user to the LDAP directory, run the following command:

“`sudo ldapadd -x -D cn=Manager,dc=my-domain,dc=com -W -f john.ldif“` This will prompt you for the root user password specified in slapd.conf and add the new user to your directory.

Advanced Configuration Options

Secure Your Connection with SSL Encryption

One of the main advantages of OpenLDAP is that it allows for secure authentication and data transfer. You can implement SSL encryption to ensure that your LDAP server is protected from unauthorized access.

To do this, you will need to obtain an SSL certificate from a trusted certificate authority, such as Let’s Encrypt or Verisign. Once you have obtained the certificate, you will need to configure your LDAP server to use it.

First, install the OpenSSL package if it is not already installed on your system. Then generate a private key and a CSR (certificate signing request) using the following command: openssl req -new -newkey rsa:2048 -nodes -keyout ldap.key -out ldap.csr

You will be prompted to answer several questions about your organization and domain name. Once you have generated the CSR, submit it to your preferred CA and wait for them to issue an SSL certificate in response. Once you receive the issued certificate from the CA, save it in a file called ldap.crt.

Then modify /etc/openldap/slapd.conf file with the following configuration: TLSVerifyClient never

TLSCertificateFile /path/to/ldap.crt TLSCertificateKeyFile /path/to/ldap.key

This enables TLS encryption on all connections established with the OpenLDAP server.

Data Replication for High Availability

Data replication in OpenLDAP is used for creating high availability clusters where multiple LDAP servers are synchronized with each other. This means that if one server fails or becomes unavailable, another replica can take over without any disruption in service.

To set up replication in OpenLDAP, you need to configure at least two LDAP servers: one master and one or more replicas. The replication process involves the transfer of changes made to the master LDAP server to all replicas.

OpenLDAP supports two types of replication: Master-Slave and Mirror Mode. In Master-Slave replication, only the master server can be modified while replica servers are read-only.

To set up Master-Slave replication, modify /etc/openldap/slapd.conf and add the following lines: syncrepl rid=123

provider=ldap:// type=refreshAndPersist

retry=”60 +” searchbase=”dc=example,dc=com”

filter=”(objectClass=*)” scope=sub

schemachecking=off bindmethod=simple

binddn=”cn=admin,dc=example,dc=com” credentials=password

In Mirror Mode replication, all servers are read/write capable so modifications can be made on any server which will then be synchronized with all other replicas. This mode is useful for load balancing and is recommended for large-scale deployments.

Access Control with ACL

OpenLDAP provides Access Control List (ACL) functionality that enables administrators to control access to the LDAP directory based on various criteria such as IP address, user group membership or password policies. The ACLs in OpenLDAP are defined using a specific syntax in the slapd.conf file. For example:

access to * by anonymous auth access to * by dn=”cn=admin,dc=my-domain-corp,dc=com” write

access to * by users read This configuration allows any authenticated user to access any LDAP entry but limits modification rights to the admin account.

All users can perform read operations on LDAP entries. To set up an ACL in OpenLDAP, you need to define the access control rules for each LDAP object by specifying the type of access allowed and the DN (Distinguished Name) of the user or group that is permitted to perform those actions.


Common issues that may arise during the installation process

While installing OpenLDAP, you may run into several issues. One common issue is the inability to connect to the LDAP server after installation. This issue can be caused by a misconfiguration of the LDAP server settings during installation.

To resolve this issue, check your configuration files and verify that all settings are correct. Additionally, ensure that any firewalls on your system are not blocking traffic to the LDAP server.

Another common issue is incorrect permissions on important files or directories. Make sure all necessary directories, such as /etc/ldap and /var/lib/ldap, have correct ownership and permissions set.

Failure to do so can cause errors with starting or stopping services related to OpenLDAP. If you experience problems while adding users or groups to your LDAP directory, double-check that your LDIF files are formatted correctly and contain all necessary attributes for each entry.

Troubleshooting tips and solutions

If you encounter an error message during installation or operation of OpenLDAP, it’s essential first to check for any relevant error logs. You can find these logs in /var/log/syslog or with journalctl commands if using systemd.

Look for specific error messages related to OpenLDAP services, such as slapd.service. If there are no clear error messages in your logs file or if you’re having trouble finding them altogether, consider increasing verbosity levels when running commands related to OpenLDAP.

For instance, when attempting an ldapsearch command use -d 1 flag at first before moving up in levels (e.g., -d 2). This increases debugging information provided by the command which helps identify issues more readily.

Make sure your system is up-to-date with the latest security patches available for both Ubuntu and CentOS distributions since many errors might be caused by outdated software versions running on your system. If all else fails, consider seeking help from the OpenLDAP community forums or mailing lists.


OpenLDAP is an essential tool for managing user accounts and groups in a network environment. Its flexibility and scalability make it an ideal choice for small to large-sized businesses.

With the step-by-step guide provided above, installing OpenLDAP on Ubuntu and CentOS should be a breeze. Overall, implementing OpenLDAP can greatly enhance the security and efficiency of a network infrastructure.

By centralizing user account management, administrators can easily add or remove users from multiple systems without having to log into each one individually. This saves time and reduces the risk of human error.

We highly recommend that anyone responsible for managing user accounts in a network environment consider implementing OpenLDAP. It may take some time to set up initially but will ultimately save time and resources in the long run.

Final Thoughts and Recommendations

In addition to implementing OpenLDAP, we recommend keeping up-to-date with security best practices such as using strong passwords, regularly updating software packages, and monitoring system logs for suspicious activity. It’s also important to regularly back up your LDAP directory data to ensure that you can quickly recover from any disasters.

We encourage readers to continue exploring the many features of OpenLDAP beyond what was covered in this article. There are many advanced configuration options available such as SSL encryption, replication, access control policies, and more.

Thank you for reading our step-by-step guide on Installing OpenLDAP on Ubuntu and CentOS! We hope it has been informative and helpful in your journey towards better user account management.

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