<?
if (isset($_GET['file'])) $file=$_GET['file']; //so it gets the GET data from url (file=filename.ext);

$ip=$_SERVER['REMOTE_ADDRESS'];
$file=fopen('download_log.html','a');
$date=date('d-m-y H:i:s');
$text="<br><hr><p>".$file.", ".$ip." on date ".$date;
fputs($file,$text); /* At that point, the download try is logged, so if he doesn't proceed the download, will be logged anyway */
/* if you want to be secure and avoid the ppl downloading what they dont have to do, you could add every file name to a MySQL DB and add an ID, so you were only to need to put in your links the id like "download.php?id=257", but thats a bit long to explain, so i continue with the simple explanation */

echo "You're going to download the file <b>".$file."</b>. If you want to proceed, click <a href='".$file"' target='_blank'><b>here</b></a>";
?>