在php中，通常我们用$_SERVER['REMOTE_ADDR']得到访问者的ip。但当访问者使用了代理，它只能得到代理的ip。这时使用下面的函数就能得到访问者的真实ip：

方法一：

function getRealIpAddr(){
	if (!empty($_SERVER['HTTP_CLIENT_IP'])){//check ip from share internet
		$ip=$_SERVER['HTTP_CLIENT_IP'];
	} elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])){//to check ip is pass from proxy
		$ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
	}else{
		$ip=$_SERVER['REMOTE_ADDR'];
	}
	return $ip;
}

方法二：

function getIP(){
	static $realip;
	if (isset($_SERVER)){
		if (isset($_SERVER["HTTP_X_FORWARDED_FOR"])){
			$realip = $_SERVER["HTTP_X_FORWARDED_FOR"];
		} else if (isset($_SERVER["HTTP_CLIENT_IP"])) {
			$realip = $_SERVER["HTTP_CLIENT_IP"];
		} else {
			$realip = $_SERVER["REMOTE_ADDR"];
		}
	} else {
		if (getenv("HTTP_X_FORWARDED_FOR")){
			$realip = getenv("HTTP_X_FORWARDED_FOR");
		} else if (getenv("HTTP_CLIENT_IP")) {
			$realip = getenv("HTTP_CLIENT_IP");
		} else {
			$realip = getenv("REMOTE_ADDR");
		}
	}
	return $realip;
}