First download the LDAP extension from MediaWikiExtension and follow the instructions given on the same page.
For running the command “ php maintenance/update.php” it’s a little trick, because sometime it happens that PHP is not configured in path variable to run on command prompt, so for this follow this article.
Configure the LDAP settings in your localsettings.php, that’s a little hack, first follow the instructions mentioned in this article, actually this is the same author's blog which wrote the plugin, so it’s very informative.
If you got the error of “Unable to start TLS: Server is unavailable” then use the following code:
$wgLDAPEncryptionType = array("group"=>"clear");
Where “group” will be replaced by the same string used in the ldap settings in localsettings.php file. Usually it’s a domain name in LDAP string for instance:
Enjoy the LDAP login!!!
If you face any issue, you can contact to me via blog comments!