How can I get the MAC and the IP address of a connected client in PHP?

Server IP

You can get the server IP address from $_SERVER['SERVER_ADDR'].

Server MAC address

For the MAC address, you could parse the output of netstat -ie in Linux, or ipconfig /all in Windows.

Client IP address

You can get the client IP from $_SERVER['REMOTE_ADDR']

Client MAC address

The client MAC address will not be available to you except in one special circumstance: if the client is on the same ethernet segment as the server.

So, if you are building some kind of LAN based system and your clients are on the same ethernet segment, then you could get the MAC address by parsing the output of arp -n (linux) or arp -a (windows).

Edit: you ask in comments how to get the output of an external command - one way is to use backticks, e.g.

$ipAddress=$_SERVER['REMOTE_ADDR'];
$macAddr=false;

#run the external command, break output into lines
$arp=`arp -a $ipAddress`;
$lines=explode("\n", $arp);

#look for the output line describing our IP address
foreach($lines as $line)
{
   $cols=preg_split('/\s+/', trim($line));
   if ($cols[0]==$ipAddress)
   {
       $macAddr=$cols[1];
   }
}

But what if the client isn't on a LAN?

Well, you're out of luck unless you can have the client volunteer that information and transmit via other means.

The MAC address of a client (in the sense of the computer that issued the HTTP request) is overwritten by every router between the client and the server.

Client IP is conveniently provided to the script in $_SERVER['REMOTE_ADDR']. In some scenarios, particularly if your web server is behind a proxy (i.e. a caching proxy) $_SERVER['REMOTE ADDR'] will return the IP of the proxy, and there will be an extra value, often $_SERVER['HTTP_X_FORWARDED_FOR'], that contains the IP of the original request client.

Sometimes, particularly when you're dealing with an anonymizing proxy that you don't control, the proxy won't return the real IP address, and all you can hope for is the IP address of the proxy.

I don't think you can get MAC address in PHP, but you can get IP from $_SERVER['REMOTE_ADDR'] variable.

For windows server I think u can use this:

<?php
echo exec('getmac');
?>