WP-antiProxy is a WordPress plugin by Rynaldo Stoltz that will fetch and auto-correct the client’s IP address in the event that he is hidden behind a proxy or load balancer.
Unlike other similar plugins, WP-antiProxy uses both uses and looks at both the HTTP headers as well as ports.
Ports: 8080,80,81,1080,6588,8000,3128,553,554,4480
Download and more info: http://wordpress.org/extend/plugins/wp-antiproxy/