互联网背后有不同类型的用户，因此我们希望从不同的部分捕获IP地址。这些都是:

1. $ _SERVER [' REMOTE_ADDR '] - 其中包含客户端的真实IP地址。这是您可以从用户那里找到的最可靠的值。

2. $ _SERVER [' REMOTE_HOST '] - 这将获取用户正在查看当前页面的主机名。但是要使这个脚本工作，必须在httpd.conf中配置主机名查找。

3.$ _SERVER [' HTTP_CLIENT_IP '] - 当用户来自共享Internet服务时，这将获取IP地址。

4. $_SERVER['HTTP_X_FORWARDED_FOR'] -这将从用户获取IP地址时，他/她是后面的代理。

所以我们可以用下面这个组合函数从不同位置观看的用户那里得到真实的IP地址，

// Function to get the user IP address
function getUserIP() {
    $ipaddress = '';
    if (isset($_SERVER['HTTP_CLIENT_IP']))
        $ipaddress = $_SERVER['HTTP_CLIENT_IP'];
    else if(isset($_SERVER['HTTP_X_FORWARDED_FOR']))
        $ipaddress = $_SERVER['HTTP_X_FORWARDED_FOR'];
    else if(isset($_SERVER['HTTP_X_FORWARDED']))
        $ipaddress = $_SERVER['HTTP_X_FORWARDED'];
    else if(isset($_SERVER['HTTP_X_CLUSTER_CLIENT_IP']))
        $ipaddress = $_SERVER['HTTP_X_CLUSTER_CLIENT_IP'];
    else if(isset($_SERVER['HTTP_FORWARDED_FOR']))
        $ipaddress = $_SERVER['HTTP_FORWARDED_FOR'];
    else if(isset($_SERVER['HTTP_FORWARDED']))
        $ipaddress = $_SERVER['HTTP_FORWARDED'];
    else if(isset($_SERVER['REMOTE_ADDR']))
        $ipaddress = $_SERVER['REMOTE_ADDR'];
    else
        $ipaddress = 'UNKNOWN';
    return $ipaddress;
}

像下面这样?

if (($ip=filter_input(INPUT_SERVER, 'REMOTE_ADDR', validate_ip)) === false or empty($ip)) {
    exit;
}
echo $ip;

PS

if (($ip=filter_input(INPUT_SERVER, 'REMOTE_ADDR', FILTER_VALIDATE_IP|FILTER_FLAG_NO_PRIV_RANGE|FILTER_FLAG_NO_RES_RANGE)) === false) {
    header('HTTP/1.0 400 Bad Request');
    exit;
}

所有以'HTTP_'或'X-'开头的报头都可能被欺骗，分别由用户定义。如果你想要跟踪，可以使用cookie等。

function get_client_ip()
{
    foreach (array(
                'HTTP_CLIENT_IP',
                'HTTP_X_FORWARDED_FOR',
                'HTTP_X_FORWARDED',
                'HTTP_X_CLUSTER_CLIENT_IP',
                'HTTP_FORWARDED_FOR',
                'HTTP_FORWARDED',
                'REMOTE_ADDR') as $key) {
        if (array_key_exists($key, $_SERVER)) {
            foreach (explode(',', $_SERVER[$key]) as $ip) {
                $ip = trim($ip);
                if ((bool) filter_var($ip, FILTER_VALIDATE_IP,
                                FILTER_FLAG_IPV4 |
                                FILTER_FLAG_NO_PRIV_RANGE |
                                FILTER_FLAG_NO_RES_RANGE)) {
                    return $ip;
                }
            }
        }
    }
    return null;
}

或压缩版:

function get_ip() {
    foreach (array('HTTP_CLIENT_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'REMOTE_ADDR') as $key) {
        if (array_key_exists($key, $_SERVER) === true) {
            foreach (array_map('trim', explode(',', $_SERVER[$key])) as $ip) {
                if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE) !== false) {
                    return $ip;
                }
            }
        }
    }
}

用于获取IP地址的安全和警告感知代码段:

$ip = filter_input(INPUT_SERVER, 'HTTP_CLIENT_IP', FILTER_VALIDATE_IP)
    ?: filter_input(INPUT_SERVER, 'HTTP_X_FORWARDED_FOR', FILTER_VALIDATE_IP)
    ?: $_SERVER['REMOTE_ADDR']
    ?? '0.0.0.0'; // Or other value fits "not defined" in your logic

试试这个:

 $_SERVER['REMOTE_ADDR'];

你可以使用下面的函数

function get_client_ip() {
    $ipaddress = '';
    if (isset($_SERVER['HTTP_CLIENT_IP']))
        $ipaddress = $_SERVER['HTTP_CLIENT_IP'];
    else if(isset($_SERVER['HTTP_X_FORWARDED_FOR']))
        $ipaddress = $_SERVER['HTTP_X_FORWARDED_FOR'];
    else if(isset($_SERVER['HTTP_X_FORWARDED']))
        $ipaddress = $_SERVER['HTTP_X_FORWARDED'];
    else if(isset($_SERVER['HTTP_FORWARDED_FOR']))
        $ipaddress = $_SERVER['HTTP_FORWARDED_FOR'];
    else if(isset($_SERVER['HTTP_FORWARDED']))
        $ipaddress = $_SERVER['HTTP_FORWARDED'];
    else if(isset($_SERVER['REMOTE_ADDR']))
        $ipaddress = $_SERVER['REMOTE_ADDR'];
    else
        $ipaddress = 'UNKNOWN';
    return $ipaddress;
}