you also could echo the *:

like:

 echo "<b> Browser: </b>"; 

then you will get less opening and closing from php.
but although nice code if you are a beginner :)

edit;

also why working with variables in this script, it is shorter I know, but not need in this script.

And try to get your variables set at the beginning of your script like:

$ip = $_SERVER['REMOTE_ADDR'];
$ip = $_SERVER['REMOTE_ADDR'];
$ip2 = $_SERVER['HTTP_REMOTE_HOST'];
$port = $_SERVER['REMOTE_PORT'];
$browser = $_SERVER['HTTP_USER_AGENT'];