PHP solution to obtain the real IP of the user client

Obtaining the client IP is actually not a simple task. Because of IP spoofing and proxy problems, the authenticity of obtaining the client IP will be compromised and cannot be 100% accurate. But we try to use more complete methods Get the client's IP. Let me share with you how to get the real IP of the user's client in PHP. Let's take a look.

Obtaining the client's IP is actually not a simple job because there are IP spoofing and proxies. problem, so the authenticity of obtaining the client's IP will be compromised and cannot be 100% accurate. But we still try to find a more complete method of obtaining the client's real IP. There are many ways to obtain the IP using php.

function getIp(){
if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown"))
$ip = getenv("HTTP_CLIENT_IP");
else if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown"))
$ip = getenv("HTTP_X_FORWARDED_FOR");
else if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown"))
$ip = getenv("REMOTE_ADDR");
else if (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown"))
$ip = $_SERVER['REMOTE_ADDR'];
else
$ip = "unknown";
return($ip);

Now we need to explain this code. Two functions are used here, getenv() and strcasecmp(). The former function obtains the system environment variables. If If the value can be obtained, it will return the value, if it cannot, it will return false.

$_SERVER is the server super global variable array. You can also use $_SERVER['REMOTE_ADDR'] to get the client's IP address. The difference between the two The reason is that getenv does not support PHP running in IIS isapi mode.

strcasecmp(string1,string2) The usage of the string function is to compare string1 and string2. If they are equal, 0 is returned. If string1 is greater than string2, the return value is greater than If it is less than 0, it will return a number less than 0.

The function first uses the customer IP. If it does not work, try to use the proxy method. If it does not work, then use REMOTE_ADDR.

I also saw one A more detailed method of detecting IP takes into account IP spoofing and multiple proxy codes. The method is similar.

function getip() {
$unknown = 'unknown';
if ( isset($_SERVER['HTTP_X_FORWARDED_FOR']) && $_SERVER['HTTP_X_FORWARDED_FOR'] && strcasecmp($_SERVER['HTTP_X_FORWARDED_FOR'], $unknown) ) {
$ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
} elseif ( isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], $unknown) ) {
$ip = $_SERVER['REMOTE_ADDR'];
}
/*
处理多层代理的情况
或者使用正则方式：$ip = preg_match("/[\d\.]{7,15}/", $ip, $matches) ? $matches[0] : $unknown;
*/
if (false !== strpos($ip, ','))
$ip = reset(explode(',', $ip));
return $ip;
}

1. No proxy server is used PHP obtains the client IP:

REMOTE_ADDR = Client IP
HTTP_X_FORWARDED_FOR = No value or no value displayed

2. When using a transparent proxy server: Transparent Proxies

REMOTE_ADDR = Last proxy server IP
HTTP_X_FORWARDED_FOR = Client real IP (when passing through multiple proxy servers, this value is similar: 221.5.252.160, 203.98.182.163, 203.129.72.215 )

This type of proxy server still sends the client’s real IP to the access object, which cannot achieve the purpose of hiding the true identity.

3. PHP using ordinary anonymous proxy servers Get the client IP: Anonymous Proxies

REMOTE_ADDR = Last proxy server IP
HTTP_X_FORWARDED_FOR = Proxy server IP (when passing through multiple proxy servers, this value is similar: 203.98.182.163, 203.98. 182.163, 203.129.72.215)

In this case, the real IP of the client is hidden, but it is revealed to the access object that the client uses a proxy server to access them.

4. The use of deceptive proxy servers: Distorting Proxies

REMOTE_ADDR = Proxy server IP
HTTP_X_FORWARDED_FOR = Random IP (when passing through multiple proxy servers, this value is similar: 220.4.251.159 , 203.98.182.163, 203.129.72.215)

In this case, it is also revealed that the client uses a proxy server, but a fake random IP (220.4.251.159) is fabricated to replace the client's real IP to deceive. It.

5. Use PHP of high anonymity proxy server to obtain client IP: High Anonymity Proxies (Elite proxies)

REMOTE_ADDR = Proxy server IP

HTTP_X_FORWARDED_FOR = No value or not displayed

Whether it is REMOTE_ADDR or HTTP_FORWARDED_FOR, these header messages may not be available because different browsers and different network devices may send different IP header messages. Therefore, PHP uses The value obtained by $_SERVER["REMOTE_ADDR"] and $_SERVER["HTTP_X_FORWARDED_FOR"] may be a null value or an "unknown" value.

Summary: The above is the entire content of this article, I hope it can help Everyone’s learning helps.

Related recommendations:

phpRegistration and login interface implementation case

php The difference between array_key_exists() and isset()

##phpPractice of building a chat room based on websocket

The above is the detailed content of PHP solution to obtain the real IP of the user client. For more information, please follow other related articles on the PHP Chinese website!