skins/<skinname>/_main.php find and add the red bit :-

$disp_comment_form = is_logged_in(); // Display the comments form if comments requested

htsrv/comment.post.php find and add the red bit :-

require_once( dirname(__FILE__) . '/../evocore/_main.inc.php' );
if ( !is_logged_in() ){
header_nocache();
header_redirect();
exit;
}

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great! thnx allot. :D

Even after adjusting the code as stated I am still getting spam. Any advice?

That should have stopped all your comment spam, which only leaves trackbacks and pingbacks, both of which can be disabled from admin > blogs > [blog name] > advanced

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