Disable edit for unregistred users

Disable edit/create page without registration.

Add into LocalSettings.php

$wgGroupPermissions['*']['edit'] = false;

// Not necessary to disable this explicity: it requires the edit right
$wgGroupPermissions['*']['createpage'] = false;
$wgGroupPermissions['*']['createtalk'] = false;

http://www.mediawiki.org/wiki/Manual:User_rights