bbPress.org

this should do it – make sure anonymous is turned on to allow creation, then this stops topics being created – ie the topic form being shown

add_filter ( 'bbp_current_user_can_publish_topics', 'rew_prevent_anonymous' );

function rew_prevent_anonymous ($retval) {
	// prevent topic creation if user is not logged in
	if ( !is_user_logged_in()) {
		$retval = false;
	}

return $retval;

}

if you don’t know how to add to the functions file, use this plugin and put the code in there

Code Snippets