Forum OpenACS Q&A: Re: How to uniquely identify user's PC without using IP address?

You could always try the following script.  I don't recommend running it more than once per session.  You need samba installed on the web server to do this but nothing samba-wise needs to be running or mounted.

set win_info [exec nmblookup -A $some_ip];

set machine_name_ptr [string first {<03>} $win_info];

set machine_name [string trim [string range $win_info [expr [string last {>} $win_info $machine_name_ptr] + 1] [expr $machine_name_ptr - 1]]]

(I don't actually use this script so I don't know how well it works.  I did test it a couple of times before posting it though.)