以下是我发现的最先进的方法，我在过去已经尝试过其他一些方法。确保获得访问者的IP地址是有效的(但请注意，任何黑客都很容易伪造IP地址)。

function get_ip_address() {

    // Check for shared Internet/ISP IP
    if (!empty($_SERVER['HTTP_CLIENT_IP']) && validate_ip($_SERVER['HTTP_CLIENT_IP'])) {
        return $_SERVER['HTTP_CLIENT_IP'];
    }

    // Check for IP addresses passing through proxies
    if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {

        // Check if multiple IP addresses exist in var
        if (strpos($_SERVER['HTTP_X_FORWARDED_FOR'], ',') !== false) {
            $iplist = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
            foreach ($iplist as $ip) {
                if (validate_ip($ip))
                    return $ip;
            }
        }
        else {
            if (validate_ip($_SERVER['HTTP_X_FORWARDED_FOR']))
                return $_SERVER['HTTP_X_FORWARDED_FOR'];
        }
    }
    if (!empty($_SERVER['HTTP_X_FORWARDED']) && validate_ip($_SERVER['HTTP_X_FORWARDED']))
        return $_SERVER['HTTP_X_FORWARDED'];
    if (!empty($_SERVER['HTTP_X_CLUSTER_CLIENT_IP']) && validate_ip($_SERVER['HTTP_X_CLUSTER_CLIENT_IP']))
        return $_SERVER['HTTP_X_CLUSTER_CLIENT_IP'];
    if (!empty($_SERVER['HTTP_FORWARDED_FOR']) && validate_ip($_SERVER['HTTP_FORWARDED_FOR']))
        return $_SERVER['HTTP_FORWARDED_FOR'];
    if (!empty($_SERVER['HTTP_FORWARDED']) && validate_ip($_SERVER['HTTP_FORWARDED']))
        return $_SERVER['HTTP_FORWARDED'];

    // Return unreliable IP address since all else failed
    return $_SERVER['REMOTE_ADDR'];
}

/**
 * Ensures an IP address is both a valid IP address and does not fall within
 * a private network range.
 */
function validate_ip($ip) {

    if (strtolower($ip) === 'unknown')
        return false;

    // Generate IPv4 network address
    $ip = ip2long($ip);

    // If the IP address is set and not equivalent to 255.255.255.255
    if ($ip !== false && $ip !== -1) {
        // Make sure to get unsigned long representation of IP address
        // due to discrepancies between 32 and 64 bit OSes and
        // signed numbers (ints default to signed in PHP)
        $ip = sprintf('%u', $ip);

        // Do private network range checking
        if ($ip >= 0 && $ip <= 50331647)
            return false;
        if ($ip >= 167772160 && $ip <= 184549375)
            return false;
        if ($ip >= 2130706432 && $ip <= 2147483647)
            return false;
        if ($ip >= 2851995648 && $ip <= 2852061183)
            return false;
        if ($ip >= 2886729728 && $ip <= 2887778303)
            return false;
        if ($ip >= 3221225984 && $ip <= 3221226239)
            return false;
        if ($ip >= 3232235520 && $ip <= 3232301055)
            return false;
        if ($ip >= 4294967040)
            return false;
    }
    return true;
}

在PHP中，获取公共IP的最后一个选项应该始终是$_SERVER["REMOTE_ADDR"]，因为有太多的安全原因。

下面是获取客户端已验证的IP地址的变通方法。

public static function getPublicIP() : string
    {
        $realIP = "Invalid IP Address";

        $activeHeaders = [];

        $headers = [
            "HTTP_CLIENT_IP",
            "HTTP_PRAGMA",
            "HTTP_XONNECTION",
            "HTTP_CACHE_INFO",
            "HTTP_XPROXY",
            "HTTP_PROXY",
            "HTTP_PROXY_CONNECTION",
            "HTTP_VIA",
            "HTTP_X_COMING_FROM",
            "HTTP_COMING_FROM",
            "HTTP_X_FORWARDED_FOR",
            "HTTP_X_FORWARDED",
            "HTTP_X_CLUSTER_CLIENT_IP",
            "HTTP_FORWARDED_FOR",
            "HTTP_FORWARDED",
            "ZHTTP_CACHE_CONTROL",
            "REMOTE_ADDR" #this should be the last option
        ];

        #Find active headers
        foreach ($headers as $key)
        {
            if (array_key_exists($key, $_SERVER))
            {
                $activeHeaders[$key] = $_SERVER[$key];
            }
        }

         #Reemove remote address since we got more options to choose from
        if(count($activeHeaders) > 1)
        {
            unset($activeHeaders["REMOTE_ADDR"]);
        }

        #Pick a random item now that we have a secure way.
        $realIP = $activeHeaders[array_rand($activeHeaders)];

        #Validate the public IP
        if (filter_var($realIP, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4))
        {
            return $realIP;
        }

        return $realIP;
    }

正如您在这里看到的，$_SERVER["REMOTE_ADDR"]是IP的最后一个选项。在收到IP后，我们也验证IP，以确保质量和安全。

它应该包含在$_SERVER['REMOTE_ADDR']变量中。

答案是使用$_SERVER变量。例如，$_SERVER["REMOTE_ADDR"]将返回客户端的IP地址。

下面的函数确定所有的可能性，并以逗号分隔的格式返回值(ip, ip等)。

它还有一个可选的验证功能(默认禁用的第一个参数)，用于根据(私有范围和保留范围)验证IP地址。

<?php
echo GetClientIP(true);

function GetClientIP($validate = False) {
  $ipkeys = array(
  'REMOTE_ADDR',
  'HTTP_CLIENT_IP',
  'HTTP_X_FORWARDED_FOR',
  'HTTP_X_FORWARDED',
  'HTTP_FORWARDED_FOR',
  'HTTP_FORWARDED',
  'HTTP_X_CLUSTER_CLIENT_IP'
  );

  /*
  Now we check each key against $_SERVER if containing such value
  */
  $ip = array();
  foreach ($ipkeys as $keyword) {
    if (isset($_SERVER[$keyword])) {
      if ($validate) {
        if (ValidatePublicIP($_SERVER[$keyword])) {
          $ip[] = $_SERVER[$keyword];
        }
      }
      else{
        $ip[] = $_SERVER[$keyword];
      }
    }
  }

  $ip = ( empty($ip) ? 'Unknown' : implode(", ", $ip) );
  return $ip;
}

function ValidatePublicIP($ip){
  if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
    return true;
  }
  else {
    return false;
  }
}

获取客户端IP地址，请使用getenv("REMOTE_ADDR")。

例如,

$ip_address = getenv("REMOTE_ADDR");
echo $ip_address;

如果你使用localhost调用你的服务器，它会输出::1。 因此，请使用直接服务器ip地址或域名调用您的服务器。