PHP获取客户端的真实ip

function getIP() {
    if (getenv('HTTP_CLIENT_IP')) {
        $ip = getenv('HTTP_CLIENT_IP');
    } elseif (getenv('HTTP_X_FORWARDED_FOR')) {
        $ip = getenv('HTTP_X_FORWARDED_FOR');
    } elseif (getenv('HTTP_X_FORWARDED')) {
        $ip = getenv('HTTP_X_FORWARDED');
    } elseif (getenv('HTTP_FORWARDED_FOR')) {
        $ip = getenv('HTTP_FORWARDED_FOR');

    } elseif (getenv('HTTP_FORWARDED')) {
        $ip = getenv('HTTP_FORWARDED');
    } else {
        $ip = $_SERVER['REMOTE_ADDR'];
    }
    return $ip;
}

get_env表示获取一个环境变量的值，可以查看官方手册的详细说明。