I've made a slight modification to this hack, so that the email also includes not only the IP name, but the host name as well.
This is the code to add:
Code:
$ipaddress=iif(getenv("REMOTE_ADDR")!="",getenv("REMOTE_ADDR"),$HTTP_HOST);
$iphostname = @gethostbyaddr($ipaddress);
$message="Someone is trying to login using your admin account!\n\nThe IP address is: $ipaddress\nThe host is: $iphostname";
mail($webmasteremail,"Warning: vBulletin Admin Login Tried",$message,"From: \"$bbtitle Admin CP\" <$webmasteremail>");
FireFly, if you like you can put that into your "official" version, or if you have any suggestions to improve what I did, please let me know.