If you have found yourself needing to access an LDAP server from PHP and your running on a DirectAdmin box you’re going to find it is not available by default.

Here is what I needed to do in order to get it running on a Debian system:

apt-get install php5-ldap libldap-dev

Copy the ldap.so file into the PHP extensions directory:

cp /usr/lib/php5/20090626/ldap.so /usr/local/lib/php/extensions/no-debug-non-zts-20090626/

Add the extension to your active php.ini file, in my case the active php.ini file was: /usr/local/lib/php.ini. You can find out the location of your working php.ini file through phpinfo().

extension=ldap.so

Restart Apache and you should be up and running (you can use phpinfo() to check if LDAP is available to you.

/etc/init.d/httpd restart