How to obtain the Client IP address in PHP

The getenv ('remote _ ADDR ') method mentioned in PHP manual has many problems in obtaining the Client IP address, therefore, it is necessary to consider using a more comprehensive method to obtain the IP address of the user client more accurately. Getenv

(PHP 3, PHP 4, PHP 5)

Getenv -- gets the value of an environment variable

Description

StringGetenv(String varname)

Returns the value of the environment variableVarname, OrFalseOn an error.

<?php// Example use of getenv()$ip= getenv('REMOTE_ADDR');// Or simply use a Superglobal ($_SERVER or $_ENV)$ip = $_SERVER['REMOTE_ADDR'];?>

This is the method provided by manual, the official PHP website.

However, when the Web Server API isAsapi (IIS)The getenv function does not work. In this case, if you use getenv to obtain the IP address of the client, the IP address is incorrect.

Therefore, the safer and more accurate method is to avoid using the getenv function. For example, you can use the following function to obtain IP information:

// Get the real client IP ("bullet-proof ")

Function getip (){
If (getenv ("http_client_ip ")&&
Strcasecmp (getenv ("http_client_ip"), "unknown "))
$ IP =
Getenv ("http_client_ip ");
Elseif (getenv ("http_x_forwarded_for ")&&
Strcasecmp (getenv ("http_x_forwarded_for"), "unknown "))
$ IP =
Getenv ("http_x_forwarded_for ");
Elseif (getenv ("remote_addr ")&&
Strcasecmp (getenv ("remote_addr"), "unknown "))
$ IP =
Getenv ("remote_addr ");
Elseif (isset ($ _ server ['remote _ ADDR ']) &
$ _ Server ['remote _ ADDR '] &
Strcasecmp ($ _ server ['remote _ ADDR '], "unknown "))
$ IP =
$ _ Server ['remote _ ADDR '];
Else
$ IP =
"Unknown ";
Return ($ IP );
}

For more detailed discussion, see http://cn.php.net/manual/zh/function.getenv.php