Banner grabber

[Extreme]

I don't meen banners in a way of comercial picture, but banner when you visit some server and it shows you what server they are running... I am trying to make my own banner grabber which would be able to see what software is the server using for any port... I found only one code but I don't know if that is anything close to it. However, I tryed it, but it doesn't give me any echo on the end. Maybe wrong code. If you have better, or know how to fix this one, please do.
function get_server_software($domain) {
$fp = fsockopen($domain, $port, $errno, $errstr, 1);

if (!$fp) {
return("");
}

else {
fputs($fp, "HEAD / HTTP/1.1\r\nHost: " . $domain . "\r\n\r\n");

while (!feof($fp)) {
if (preg_match("/\bServer:/", $server = fgets($fp, 256))) {
fclose($fp);
return(substr($server, 8, -2));
}
}

fclose($fp);
}
}