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。
我想出了这个函数，它不简单地返回IP地址，而是一个具有IP信息的数组。
// Example usage:
$info = ip_info();
if ( $info->proxy ) {
echo 'Your IP is ' . $info->ip;
} else {
echo 'Your IP is ' . $info->ip . ' and your proxy is ' . $info->proxy_ip;
}
函数如下:
/**
* 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.
*
* @since 1.1.3
*
* @return object {
* IP Address details
*
* string $ip The users IP address (might be spoofed, if $proxy is true)
* bool $proxy True, if a proxy was detected
* string $proxy_id The proxy-server IP address
* }
*/
function ip_info() {
$result = (object) array(
'ip' => $_SERVER['REMOTE_ADDR'],
'proxy' => false,
'proxy_ip' => '',
);
/*
* This code tries to bypass a proxy and get the actual IP address of
* the visitor behind the proxy.
* Warning: These values might be spoofed!
*/
$ip_fields = array(
'HTTP_CLIENT_IP',
'HTTP_X_FORWARDED_FOR',
'HTTP_X_FORWARDED',
'HTTP_X_CLUSTER_CLIENT_IP',
'HTTP_FORWARDED_FOR',
'HTTP_FORWARDED',
'REMOTE_ADDR',
);
foreach ( $ip_fields as $key ) {
if ( array_key_exists( $key, $_SERVER ) === true ) {
foreach ( explode( ',', $_SERVER[$key] ) as $ip ) {
$ip = trim( $ip );
if ( filter_var( $ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE ) !== false ) {
$forwarded = $ip;
break 2;
}
}
}
}
// If we found a different IP address then REMOTE_ADDR then it's a proxy!
if ( $forwarded != $result->ip ) {
$result->proxy = true;
$result->proxy_ip = $result->ip;
$result->ip = $forwarded;
}
return $result;
}
如果你使用CloudFlare缓存层服务，下面是修改后的版本
function getIP()
{
$fields = array('HTTP_X_FORWARDED_FOR',
'REMOTE_ADDR',
'HTTP_CF_CONNECTING_IP',
'HTTP_X_CLUSTER_CLIENT_IP');
foreach($fields as $f)
{
$tries = $_SERVER[$f];
if (empty($tries))
continue;
$tries = explode(',',$tries);
foreach($tries as $try)
{
$r = filter_var($try,
FILTER_VALIDATE_IP, FILTER_FLAG_IPV4 |
FILTER_FLAG_NO_PRIV_RANGE |
FILTER_FLAG_NO_RES_RANGE);
if ($r !== false)
{
return $try;
}
}
}
return false;
}
我想出了这个函数，它不简单地返回IP地址，而是一个具有IP信息的数组。
// Example usage:
$info = ip_info();
if ( $info->proxy ) {
echo 'Your IP is ' . $info->ip;
} else {
echo 'Your IP is ' . $info->ip . ' and your proxy is ' . $info->proxy_ip;
}
函数如下:
/**
* 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.
*
* @since 1.1.3
*
* @return object {
* IP Address details
*
* string $ip The users IP address (might be spoofed, if $proxy is true)
* bool $proxy True, if a proxy was detected
* string $proxy_id The proxy-server IP address
* }
*/
function ip_info() {
$result = (object) array(
'ip' => $_SERVER['REMOTE_ADDR'],
'proxy' => false,
'proxy_ip' => '',
);
/*
* This code tries to bypass a proxy and get the actual IP address of
* the visitor behind the proxy.
* Warning: These values might be spoofed!
*/
$ip_fields = array(
'HTTP_CLIENT_IP',
'HTTP_X_FORWARDED_FOR',
'HTTP_X_FORWARDED',
'HTTP_X_CLUSTER_CLIENT_IP',
'HTTP_FORWARDED_FOR',
'HTTP_FORWARDED',
'REMOTE_ADDR',
);
foreach ( $ip_fields as $key ) {
if ( array_key_exists( $key, $_SERVER ) === true ) {
foreach ( explode( ',', $_SERVER[$key] ) as $ip ) {
$ip = trim( $ip );
if ( filter_var( $ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE ) !== false ) {
$forwarded = $ip;
break 2;
}
}
}
}
// If we found a different IP address then REMOTE_ADDR then it's a proxy!
if ( $forwarded != $result->ip ) {
$result->proxy = true;
$result->proxy_ip = $result->ip;
$result->ip = $forwarded;
}
return $result;
}
/**
* 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);
}
然而，即使这样，获取用户的真实IP地址也是不可靠的。他们所需要做的就是使用一个匿名的代理服务器(一个不尊重http_x_forwarded_for, http_forwarded等的头)，你得到的只是他们的代理服务器的IP地址。
然后，您可以查看是否有一个匿名的代理服务器IP地址列表，但没有办法确保这是100%准确的，它所做的最多是让您知道这是一个代理服务器。如果有人很聪明，他们可以欺骗HTTP转发的报头。
假设我不喜欢当地的大学。我知道他们注册了什么IP地址，然后通过做坏事让他们的IP地址在你的网站上被禁止，因为我知道你遵守HTTP转发。这样的例子不胜枚举。
然后，正如您所猜测的那样，还有内部IP地址，例如我前面提到的学院网络。很多人使用10.x.x。x格式。所以你只知道它被转发到一个共享网络。
那我就不多说了，动态IP地址已经是宽带的方式了。所以。即使你获得了一个用户IP地址，预计它最多2 - 3个月就会改变。
