title: Getting something unique about user's computer with JavaScript?
body: <p>Here's the idea:
  If I can get something unique about a computer with JavaScript from an HTML page (probably the MAC address), then can I use this data as another security check?
  Is that possible?</p>
  
  <p>I am not going to check the computer at client side, i am going to send it to server to check. If nothing sent, user will be blocked. So it is not something that any developer+firebug combination can bypass. I just want to send one more string with username and password which is unique to computer and no one else knows if they don't entered to the system from that computer. Like a password hidden from user itself.</p>