使用MaxMind GeoIP(或GeoIPLite，如果你还没有准备好支付)。

$gi = geoip_open('GeoIP.dat', GEOIP_MEMORY_CACHE);
$country = geoip_country_code_by_addr($gi, $_SERVER['REMOTE_ADDR']);
geoip_close($gi);

我知道这是旧的，但我尝试了其他一些解决方案在这里，他们似乎是过时的或只是返回null。我是这么做的。

使用http://www.geoplugin.net/json.gp?ip=，不需要任何类型的注册或支付服务。

function get_client_ip_server() {
  $ipaddress = '';
if (isset($_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;
}

$ipaddress = get_client_ip_server();

function getCountry($ip){
    $curlSession = curl_init();
    curl_setopt($curlSession, CURLOPT_URL, 'http://www.geoplugin.net/json.gp?ip='.$ip);
    curl_setopt($curlSession, CURLOPT_BINARYTRANSFER, true);
    curl_setopt($curlSession, CURLOPT_RETURNTRANSFER, true);

    $jsonData = json_decode(curl_exec($curlSession));
    curl_close($curlSession);

    return $jsonData->geoplugin_countryCode;
}

echo "County: " .getCountry($ipaddress);

如果你想要更多关于它的信息，这是一个完整的Json返回:

{
  "geoplugin_request":"IP_ADDRESS",
  "geoplugin_status":200,
  "geoplugin_delay":"2ms",
  "geoplugin_credit":"Some of the returned data includes GeoLite data created by MaxMind, available from <a href='http:\/\/www.maxmind.com'>http:\/\/www.maxmind.com<\/a>.",
  "geoplugin_city":"Current City",
  "geoplugin_region":"Region",
  "geoplugin_regionCode":"Region Code",
  "geoplugin_regionName":"Region Name",
  "geoplugin_areaCode":"",
  "geoplugin_dmaCode":"650",
  "geoplugin_countryCode":"US",
  "geoplugin_countryName":"United States",
  "geoplugin_inEU":0,
  "geoplugin_euVATrate":false,
  "geoplugin_continentCode":"NA",
  "geoplugin_continentName":"North America",
  "geoplugin_latitude":"37.5563",
  "geoplugin_longitude":"-99.9413",
  "geoplugin_locationAccuracyRadius":"5",
  "geoplugin_timezone":"America\/Chicago",
  "geoplugin_currencyCode":"USD",
  "geoplugin_currencySymbol":"$",
  "geoplugin_currencySymbol_UTF8":"$",
  "geoplugin_currencyConverter":1
}

您可以使用此代码片段。

 if($a = unserialize(file_get_contents('http://www.geoplugin.net/php.gp?ip='.$_SERVER['REMOTE_ADDR']))){
        $countrycode= $a['geoplugin_countryCode'];
        if ($countrycode=='UK' ){
            header( 'Location: https://www.example.co.uk/' ) ;exit;
        }
    }

您可以使用http://ip-api.com上的web服务 在PHP代码中，执行如下操作:

<?php
$ip = $_REQUEST['REMOTE_ADDR']; // the IP address to query
$query = @unserialize(file_get_contents('http://ip-api.com/php/'.$ip));
if($query && $query['status'] == 'success') {
  echo 'Hello visitor from '.$query['country'].', '.$query['city'].'!';
} else {
  echo 'Unable to get location';
}
?>

查询有许多其他信息:

array (
  'status'      => 'success',
  'country'     => 'COUNTRY',
  'countryCode' => 'COUNTRY CODE',
  'region'      => 'REGION CODE',
  'regionName'  => 'REGION NAME',
  'city'        => 'CITY',
  'zip'         => ZIP CODE,
  'lat'         => LATITUDE,
  'lon'         => LONGITUDE,
  'timezone'    => 'TIME ZONE',
  'isp'         => 'ISP NAME',
  'org'         => 'ORGANIZATION NAME',
  'as'          => 'AS NUMBER / NAME',
  'query'       => 'IP ADDRESS USED FOR QUERY',
)

在code.google上查看php-ip-2-country。他们提供的数据库每天都会更新，所以如果你拥有自己的SQL服务器，就没有必要连接到外部服务器进行检查。所以使用代码你只需要输入:

<?php
$ip = $_SERVER['REMOTE_ADDR'];

if(!empty($ip)){
        require('./phpip2country.class.php');

        /**
         * Newest data (SQL) avaliable on project website
         * @link http://code.google.com/p/php-ip-2-country/
         */
        $dbConfigArray = array(
                'host' => 'localhost', //example host name
                'port' => 3306, //3306 -default mysql port number
                'dbName' => 'ip_to_country', //example db name
                'dbUserName' => 'ip_to_country', //example user name
                'dbUserPassword' => 'QrDB9Y8CKMdLDH8Q', //example user password
                'tableName' => 'ip_to_country', //example table name
        );

        $phpIp2Country = new phpIp2Country($ip,$dbConfigArray);
        $country = $phpIp2Country->getInfo(IP_COUNTRY_NAME);
        echo $country;
?>

示例代码(来自资源)

<?
require('phpip2country.class.php');

$dbConfigArray = array(
        'host' => 'localhost', //example host name
        'port' => 3306, //3306 -default mysql port number
        'dbName' => 'ip_to_country', //example db name
        'dbUserName' => 'ip_to_country', //example user name
        'dbUserPassword' => 'QrDB9Y8CKMdLDH8Q', //example user password
        'tableName' => 'ip_to_country', //example table name
);

$phpIp2Country = new phpIp2Country('213.180.138.148',$dbConfigArray);

print_r($phpIp2Country->getInfo(IP_INFO));
?>

输出

Array
(
    [IP_FROM] => 3585376256
    [IP_TO] => 3585384447
    [REGISTRY] => RIPE
    [ASSIGNED] => 948758400
    [CTRY] => PL
    [CNTRY] => POL
    [COUNTRY] => POLAND
    [IP_STR] => 213.180.138.148
    [IP_VALUE] => 3585378964
    [IP_FROM_STR] => 127.255.255.255
    [IP_TO_STR] => 127.255.255.255
)

不确定这是否是一个新的服务，但现在(2016)在php中最简单的方法是使用geoplugin的php web服务:http://www.geoplugin.net/php.gp:

基本用法:

// GET IP ADDRESS
if (!empty($_SERVER['HTTP_CLIENT_IP'])) {
    $ip = $_SERVER['HTTP_CLIENT_IP'];
} else if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
    $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
} else if (!empty($_SERVER['REMOTE_ADDR'])) {
    $ip = $_SERVER['REMOTE_ADDR'];
} else {
    $ip = false;
}

// CALL THE WEBSERVICE
$ip_info = unserialize(file_get_contents('http://www.geoplugin.net/php.gp?ip='.$ip));

它们还提供了一个现成的类:http://www.geoplugin.com/_media/webservices/geoplugin.class.php.tgz?id=webservices%3Aphp&cache=cache