# Disable reading line, for anonymous (not-logged-in => * ) : $wgGroupPermissions['*']['read'] = false;
http://meta.wikimedia.org/wiki/MediaWiki_FAQ#Basic_User_Account_Management.3F http://meta.wikimedia.org/wiki/Access_Restrictions#1.5_Upwards
In order to prevent readings from anonymous users you need to set (in /LocalSettings.php):
# Disable reading line, for anonymous (not-logged-in => * ) : $wgGroupPermissions['*']['read'] = false;
http://www.mediawiki.org/wiki/Extension:PageSecurity
PageSecurity is an extension to MediaWiki that implements page access control. It can enforce read and write protection for selected pages or for sets of pages. User access is controlled by membership in user groups.