Control or Plugin to run on a browser and get a user\'s MAC address

I need a control or plugin to run on a browser and get a user's MAC address. The control or plugin needs to be able to get this MAC address from computers from behind a Proxy, firewall or antivirus etc. In addition I need a HTML page which uses the control or plugin. This HTML page is test the script and to display the MAC Address of the computer on which the browser is working. The control or plugin should work on all major browsers, IE, Chrome, Mozilla, Firefox and Safari. If required you can make separate controls or plugins for different browsers. The goal of this project is to be used in the security layer of a web application login page. Users of this application will have their MAC address resolved to determine if they are allowed to login to the web application.