$_SERVER parameters HTTP_X_FORWARDED_FOR & REMOTE_ADDR and getting IP_PHP tutorial

1.REMOTE_ADDR: IP address of the user’s computer browsing the current page 2.HTTP_X_FORWARDED_FOR: The gateway of the user’s computer browsing the current page 3.HTTP_CLIENT_IP: client’s ip

Use $_SERVER["REMOTE_ADDR"] in PHP to obtain the client's IP address. However, if the client uses a proxy server to access, the IP address obtained is the proxy server's IP address, not the real client IP. address. To obtain the client's real IP address through a proxy server, use $_SERVER["HTTP_X_FORWARDED_FOR"] to read it.

However, it should be noted that not every proxy server can use $_SERVER["HTTP_X_FORWARDED_FOR"] to read the real IP of the client. Some of the IPs read by this method are still the IP of the proxy server.

Another thing to note is that if the client does not access through a proxy server, the value obtained with $_SERVER["HTTP_X_FORWARDED_FOR"] will be empty. Therefore, if you want to use this method in your program, you can do it like this:

The code is as follows

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代码如下	复制代码
if ($_SERVER["HTTP_X_FORWARDED_FOR"]==”") { $user_ip=$_SERVER["REMOTE_ADDR"]; } else $user_ip=$_SERVER["HTTP_X_FORWARDED_FOR"]; ?>

if ($_SERVER["HTTP_X_FORWARDED_FOR"]==”")

{

代码如下

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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); }

<🎜>$user_ip=$_SERVER["REMOTE_ADDR"];<🎜> <🎜>}<🎜> <🎜>else<🎜> <🎜>$user_ip=$_SERVER["HTTP_X_FORWARDED_FOR"];<🎜> <🎜>?>

That is: if the client passes through the proxy server, the value of HTTP_X_FORWARDED_FOR is taken. If the client does not pass through the proxy server, the value of REMOTE_ADDR is taken. Get the real IP address of the client

The code is as follows

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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); }

Get the difference between the three attributes of the user's IP address (HTTP_X_FORWARDED_FOR, HTTP_VIA, REMOTE_ADDR)
1. Situation without using proxy server:

REMOTE_ADDR = your IP
HTTP_VIA = No value or not displayed
HTTP_X_FORWARDED_FOR = No value or no value

2. The use of transparent proxy servers: Transparent Proxies

REMOTE_ADDR = 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 the person you are visiting, and cannot achieve the purpose of hiding your true identity.

3. The situation of 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.

Hide your real IP, but reveal to your visitors 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. The use of high-anonymity proxy servers: High Anonymity Proxies (Elite proxies)

REMOTE_ADDR = proxy server IP
HTTP_VIA = No value or not displayed
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.

The code is as follows

代码如下

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if ($HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"]) { $ip = $HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"]; } elseif ($HTTP_SERVER_VARS["HTTP_CLIENT_IP"]) { $ip = $HTTP_SERVER_VARS["HTTP_CLIENT_IP"]; } elseif ($HTTP_SERVER_VARS["REMOTE_ADDR"]) { $ip = $HTTP_SERVER_VARS["REMOTE_ADDR"]; } elseif (getenv("HTTP_X_FORWARDED_FOR")) { $ip = getenv("HTTP_X_FORWARDED_FOR"); } elseif (getenv("HTTP_CLIENT_IP")) { $ip = getenv("HTTP_CLIENT_IP"); } elseif (getenv("REMOTE_ADDR")) { $ip = getenv("REMOTE_ADDR"); } else { $ip = "Unknown"; } echo "你的IP:".$ip ; ?>

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if ($HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"])

{

$ip = $HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"]; } elseif ($HTTP_SERVER_VARS["HTTP_CLIENT_IP"]) { $ip = $HTTP_SERVER_VARS["HTTP_CLIENT_IP"]; } elseif ($HTTP_SERVER_VARS["REMOTE_ADDR"]) { $ip = $HTTP_SERVER_VARS["REMOTE_ADDR"]; } elseif (getenv("HTTP_X_FORWARDED_FOR")) { $ip = getenv("HTTP_X_FORWARDED_FOR");

}

elseif (getenv("HTTP_CLIENT_IP"))