Problem getting real IP in php

Question

I am using this to get real IP but I take empty from $_SERVER['HTTP_CLIENT_IP'], I take not empty only from $_SERVER['REMOTE_ADDR'] .But I dont need the IP of proxy, I need the real ip of computers using some intranet. Can I get it? When $_SERVER['HTTP_CLIENT_IP'] does not return empty?

function getRealIpAddr()
{
    if (!empty($_SERVER['HTTP_CLIENT_IP']))   //check ip from share internet
    {
      $ip=$_SERVER['HTTP_CLIENT_IP'];
    }
    elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR']))   //to check ip is pass from proxy
    {
      $ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
    }
    else
    {
      $ip=$_SERVER['REMOTE_ADDR'];
    }
    return $ip;
}

Answer 1

HTTP_CLIENT_IP is not specified in the $_SERVER documentation... It may be available as an environmental variable (under $_ENV), but it's not in $_SERVER. The method you're using (going to HTTP_X_FORWARDED_FOR, then falling back on REMOTE_ADDR) is about the best you can do...

Answer 2

What you are doing is about all that you can do to get this information. I'm not 100% sure what you are saying, but try the 2 methods below to see if they give you different/better info.

Try:

$headers = apache_request_headers(); 
echo $headers['X-Forwarded-For'];

Or:

$ip_list = getenv('HTTP_X_FORWARDED_FOR');
echo $ip_list;

Answer 3

Anonymizing proxies will not populate HTTP_X_FORWARDED_FOR or REMOTE_ADDR, or will populate them using their own IP addresses, not the client IP address.

If you are working on something where you absolutely must identify the ip address of the gateway the client computer is using and are having to deal with situations where anonymizing proxies are being used, then you will have to come up with something else. I have in the past, used flash to make a socket connection to the server and send a unique key provided to the flash via params.

Be aware though that this is not a perfect solution. But in the case I was using it, to prevent cheating on a voting app, it worked fine. No flash, no vote. Similar things could be done with Java applets, silverlight, etc. Any client tech where you can specify the port that you talk to the server with. You would not want to use 80, 8080, etc, any of the common proxy ports.

Answer 4

It's not possible to resolve this 100% of the time, but this would get you about as close as possible:

if($_SERVER["HTTP_X_FORWARDED_FOR"]) {
    if($_SERVER["HTTP_CLIENT_IP"]) {
        $proxy = $_SERVER["HTTP_CLIENT_IP"];
    } else {
        $proxy = $_SERVER["REMOTE_ADDR"];
    }

    $ip = $_SERVER["HTTP_X_FORWARDED_FOR"];
} else {
    if($_SERVER["HTTP_CLIENT_IP"]) {
        $ip = $_SERVER["HTTP_CLIENT_IP"];
    } else {
        $ip = $_SERVER["REMOTE_ADDR"];
    }
}

echo "IP resolved to: ".$ip." (could still be a proxy IP though)<br>";
if($proxy) echo "Proxied through: ".$proxy;