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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