我知道有大量的$_SERVER变量头可用于IP地址检索。我想知道是否有一个普遍的共识，如何最准确地检索用户的真实IP地址(好知道没有方法是完美的)使用上述变量?
我花了一些时间试图找到一个深入的解决方案，并根据一些来源提出了以下代码。如果有人能在答案中找出漏洞，或者提供一些更准确的信息，我会很高兴。
edit包含来自@Alix的优化
/**
* Retrieves the best guess of the client's actual IP address.
* Takes into account numerous HTTP proxy headers due to variations
* in how different ISPs handle IP addresses in headers between hops.
*/
public function get_ip_address() {
// Check for shared internet/ISP IP
if (!empty($_SERVER['HTTP_CLIENT_IP']) && $this->validate_ip($_SERVER['HTTP_CLIENT_IP']))
return $_SERVER['HTTP_CLIENT_IP'];
// Check for IPs passing through proxies
if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
// Check if multiple IP addresses exist in var
$iplist = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
foreach ($iplist as $ip) {
if ($this->validate_ip($ip))
return $ip;
}
}
}
if (!empty($_SERVER['HTTP_X_FORWARDED']) && $this->validate_ip($_SERVER['HTTP_X_FORWARDED']))
return $_SERVER['HTTP_X_FORWARDED'];
if (!empty($_SERVER['HTTP_X_CLUSTER_CLIENT_IP']) && $this->validate_ip($_SERVER['HTTP_X_CLUSTER_CLIENT_IP']))
return $_SERVER['HTTP_X_CLUSTER_CLIENT_IP'];
if (!empty($_SERVER['HTTP_FORWARDED_FOR']) && $this->validate_ip($_SERVER['HTTP_FORWARDED_FOR']))
return $_SERVER['HTTP_FORWARDED_FOR'];
if (!empty($_SERVER['HTTP_FORWARDED']) && $this->validate_ip($_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.
*
* @access public
* @param string $ip
*/
public function validate_ip($ip) {
if (filter_var($ip, FILTER_VALIDATE_IP,
FILTER_FLAG_IPV4 |
FILTER_FLAG_IPV6 |
FILTER_FLAG_NO_PRIV_RANGE |
FILTER_FLAG_NO_RES_RANGE) === false)
return false;
self::$ip = $ip;
return true;
}
警告之词(更新)
REMOTE_ADDR仍然表示最可靠的IP地址来源。这里提到的其他$_SERVER变量很容易被远程客户端欺骗。此解决方案的目的是试图确定位于代理后面的客户机的IP地址。出于一般目的，您可以考虑将其与直接从$_SERVER['REMOTE_ADDR']返回的IP地址结合使用，并存储两者。
对于99.9%的用户，这个解决方案将完美地满足您的需求。它不能保护您免受0.1%的恶意用户通过注入他们自己的请求头来滥用您的系统。如果某些关键任务依赖于IP地址，请使用REMOTE_ADDR，而不必费心满足代理背后的需求。
我很惊讶没有人提到filter_input，所以这里是Alix Axel的回答浓缩成一行:
function get_ip_address(&$keys = ['HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'HTTP_CLIENT_IP', 'REMOTE_ADDR'])
{
return empty($keys) || ($ip = filter_input(INPUT_SERVER, array_pop($keys), FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE))? $ip : get_ip_address($keys);
}
/**
* Sanitizes IPv4 address according to Ilia Alshanetsky's book
* "php|architect?s Guide to PHP Security", chapter 2, page 67.
*
* @param string $ip An IPv4 address
*/
public static function sanitizeIpAddress($ip = '')
{
if ($ip == '')
{
$rtnStr = '0.0.0.0';
}
else
{
$rtnStr = long2ip(ip2long($ip));
}
return $rtnStr;
}
//---------------------------------------------------
/**
* Returns the sanitized HTTP_X_FORWARDED_FOR server variable.
*
*/
public static function getXForwardedFor()
{
if (isset($_SERVER['HTTP_X_FORWARDED_FOR']))
{
$rtnStr = $_SERVER['HTTP_X_FORWARDED_FOR'];
}
elseif (isset($HTTP_SERVER_VARS['HTTP_X_FORWARDED_FOR']))
{
$rtnStr = $HTTP_SERVER_VARS['HTTP_X_FORWARDED_FOR'];
}
elseif (getenv('HTTP_X_FORWARDED_FOR'))
{
$rtnStr = getenv('HTTP_X_FORWARDED_FOR');
}
else
{
$rtnStr = '';
}
// Sanitize IPv4 address (Ilia Alshanetsky):
if ($rtnStr != '')
{
$rtnStr = explode(', ', $rtnStr);
$rtnStr = self::sanitizeIpAddress($rtnStr[0]);
}
return $rtnStr;
}
//---------------------------------------------------
/**
* Returns the sanitized REMOTE_ADDR server variable.
*
*/
public static function getRemoteAddr()
{
if (isset($_SERVER['REMOTE_ADDR']))
{
$rtnStr = $_SERVER['REMOTE_ADDR'];
}
elseif (isset($HTTP_SERVER_VARS['REMOTE_ADDR']))
{
$rtnStr = $HTTP_SERVER_VARS['REMOTE_ADDR'];
}
elseif (getenv('REMOTE_ADDR'))
{
$rtnStr = getenv('REMOTE_ADDR');
}
else
{
$rtnStr = '';
}
// Sanitize IPv4 address (Ilia Alshanetsky):
if ($rtnStr != '')
{
$rtnStr = explode(', ', $rtnStr);
$rtnStr = self::sanitizeIpAddress($rtnStr[0]);
}
return $rtnStr;
}
//---------------------------------------------------
/**
* Returns the sanitized remote user and proxy IP addresses.
*
*/
public static function getIpAndProxy()
{
$xForwarded = self::getXForwardedFor();
$remoteAddr = self::getRemoteAddr();
if ($xForwarded != '')
{
$ip = $xForwarded;
$proxy = $remoteAddr;
}
else
{
$ip = $remoteAddr;
$proxy = '';
}
return array($ip, $proxy);
}
虽然这篇文章很老了，但这个话题仍然值得关注。所以我在我的项目中使用了另一个解决方案。我在这里找到了其他的解决方案，要么不完整，要么太复杂，难以理解。
if (! function_exists('get_visitor_IP'))
{
/**
* Get the real IP address from visitors proxy. e.g. Cloudflare
*
* @return string IP
*/
function get_visitor_IP()
{
// Get real visitor IP behind CloudFlare network
if (isset($_SERVER["HTTP_CF_CONNECTING_IP"])) {
$_SERVER['REMOTE_ADDR'] = $_SERVER["HTTP_CF_CONNECTING_IP"];
$_SERVER['HTTP_CLIENT_IP'] = $_SERVER["HTTP_CF_CONNECTING_IP"];
}
// Sometimes the `HTTP_CLIENT_IP` can be used by proxy servers
$ip = @$_SERVER['HTTP_CLIENT_IP'];
if (filter_var($ip, FILTER_VALIDATE_IP)) {
return $ip;
}
// Sometimes the `HTTP_X_FORWARDED_FOR` can contain more than IPs
$forward_ips = @$_SERVER['HTTP_X_FORWARDED_FOR'];
if ($forward_ips) {
$all_ips = explode(',', $forward_ips);
foreach ($all_ips as $ip) {
if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)){
return $ip;
}
}
}
return $_SERVER['REMOTE_ADDR'];
}
}
