Introduction to the method of obtaining the real IP of the real client in PHP

REMOTE_ADDR is the IP when your client "handshakes" with your server. If an "anonymous proxy" is used, REMOTE_ADDR will display the IP of the proxy server.

HTTP_CLIENT_IP is the HTTP header sent by the proxy server. If it is a "super anonymous proxy", a value of none is returned. Likewise, REMOTE_ADDR will be replaced with the IP of this proxy server.

$_SERVER['REMOTE_ADDR']; //Accessing end (may be user, may be proxy) IP

$_SERVER['HTTP_CLIENT_IP']; //Agent end ( It may exist and can be forged)

$_SERVER['HTTP_X_FORWARDED_FOR']; //Which IP the user is using as a proxy (It may exist and it can also be forged)

The difference between the three values ​​is as follows:

1. When no proxy server is used:

REMOTE_ADDR = Your IP

HTTP_VIA = No value or not displayed

HTTP_X_FORWARDED_FOR = No value or not displayed

2. When using a transparent proxy server: Transparent Proxies

REMOTE_ADDR = The last proxy server IP

HTTP_VIA = Proxy server IP

HTTP_X_FORWARDED_FOR = your real IP. When passing through multiple proxy servers, this value is similar to the following: 203.98.182.163, 203.98.182.163, 203.129.72.215.

This type of proxy server still forwards your information to your visitor, which cannot achieve the purpose of hiding your true identity.

3. When using ordinary anonymous proxy servers: Anonymous Proxies

REMOTE_ADDR = Last proxy server IP

HTTP_VIA = Proxy server IP

HTTP_X_FORWARDED_FOR = Proxy server IP, when passing through multiple proxy servers, this value is similar to the following: 203.98.182.163, 203.98.182.163, 203.129.72.215.

Hides your real IP, but reveals to the target audience that you are using a proxy server to access them.

4. The use of deceptive proxy servers: Distorting Proxies

REMOTE_ADDR = Proxy server IP

HTTP_VIA = Proxy server IP

HTTP_X_FORWARDED_FOR = Random IP, when passing through multiple proxy servers, this value is similar to the following: 203.98.182.163, 203.98.182.163, 203.129.72.215.

Tell the visitor that you are using a proxy server, but make up a fake random IP instead of your real IP to trick it.

5. When using a high-anonymity proxy server: High Anonymity Proxies (Elite proxies)

REMOTE_ADDR = Proxy server IP

HTTP_VIA = No value or no display

HTTP_X_FORWARDED_FOR = No value or not displayed. When passing through multiple proxy servers, this value is similar to the following: 203.98.182.163, 203.98.182.163, 203.129.72.215.

Completely replaces all your information with the proxy server's information, just like you are using that proxy server to directly access the object.

//获取用户IP
$ip = '';
foreach (array('HTTP_CLIENT_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_FROM', 'REMOTE_ADDR') as $v) {
  if (isset($_SERVER[$v])) {
    if (! preg_match('/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/', $_SERVER[$v])) {
        continue;
  } 
     $ip = $_SERVER[$v];
  }
}
uset($ip,$v);

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