Get a real IP vs Proxy

This function will try to "guess" a real IP vs Proxy

<?php
	function get_real_ip()
    {

		if (isset($_SERVER["HTTP_CLIENT_IP"]))
        {
			return $_SERVER["HTTP_CLIENT_IP"];
		}
		elseif (isset($_SERVER["HTTP_X_FORWARDED_FOR"]))
        {
			return $_SERVER["HTTP_X_FORWARDED_FOR"];
		}
		elseif (isset($_SERVER["HTTP_X_FORWARDED"]))
        {
			return $_SERVER["HTTP_X_FORWARDED"];
		}
		elseif (isset($_SERVER["HTTP_FORWARDED_FOR"]))
        {
			return $_SERVER["HTTP_FORWARDED_FOR"];
		}
		elseif (isset($_SERVER["HTTP_FORWARDED"]))
        {
			return $_SERVER["HTTP_FORWARDED"];
		}
		else
        {
			return $_SERVER["REMOTE_ADDR"];
		}

	}
    echo get_real_ip();
?>