LDAP authentication requires a LDAP extension for PHP, so you have to install it before you use it.

1. Install LDAP in Windows

1.1  If your PHP already has php_ldap.dll, you can open the php.ini file, find the ";extension=php_ldap.dll" and save the file after removing the ";".
1.2  If you do not have php_ldap.dll, first find the online PHP files accordingly and place it in the appropriate directory, then repeat the instruction mentioned above.

1.3  Restart Apache.

2. Install LDAP in Linux

2.1 If your PHP is compiled and installed, you need to add the "--with- ldap " to recompile the installation.
2.2 If your PHP is installed through the Linux package manager, you can install the php_ldap through the package manager. Taking Debian as an example, implement apt-get install php5-ldap.

2.3  Restart Apache.

3. Check the installation

Open the phpinfo () test screen. If you can see the following the screenshot,  that means the installation is done.