This isn't really a javascript question, I think. I think this is a question about how to get the Windows File Sharing name of a client who is connecting to the website. The long and short of it is that you have to have http://samba.org (Samba File Sharing) or run the perl script on a windows machine with microsoft networking. There are perl modules that create an interface for you to samba (search cpan for a list). I think you'd have to do some kind of funky reverse lookup by IP address.

# Environment variables aren't particularly safe.  
# Make sure you clean the address first

$address = $ENV{REMOTE_ADDRESS};
$name = `nmblookup -A $address`;

# parse $name for the information you actually want. 
# nmblookup returns a lot more information than just name
[download]

If you don't have samba installed, you are probably out of luck. You could try a search for SMB networking for the server OS you are running. If you are running the script on a windows machine, you'll have to figure that command out for yourself. It probably has to do with 'net' or something...