Checking if it is installed
To check if the PHP LDAP Module is installed on your server, use Tiki Check and search for a section labelled "ldap".
Installing
Depending on your server distribution/installation the method to install it would be different. For example:
- Ubuntu
- apt-get install php5-ldap
- CentOS
- yum install php-ldap
You should restart apache after installing the ldap module