MAC-Address Detection

[Anon]

I am trying to get a list of all my client computers MAC-addresses for authentication purposes. I would like to be able to detect there MAC-Address automatically when they enter my website so that it could be sent to the database.
Any Idea on how to do this using HTML or PHP or JAVA ...

Any help would be much appreciated,
[e-mail]

[Anon]

A Mac address is usually for INTERNAL use. You trying to get a MAC address would be like trying to get an IP number from an internal range.

[Anon]

You can't really rely on a MAC address for security, anyway, because any router can easily clone a MAC address and all users behind a gateway would appear to have the same MAC address.