Stopping WordPress trackback spam without plugin

What is the most effective method for combating the trackback spam that inundates comment sections?

Altering the global Trackbacks configuration through the Dashboard -> Settings -> Discussion will exclusively modify the default behavior.

If you presently have posts or pages with trackbacks enabled, adjusting the default setting won’t affect the individual post-level settings.

To address this issue use the following filter to programmatically disapprove any trackback or pingback:

 add_filter('pre_comment_approved',function($approved,$comment){
		
	if( in_array($comment['comment_type'],array(
			
		'trackback',
		'pingback',
		
	))){
        
		$approved = false;
	}
		
	return $approved;
		
},999999,2);