ActiveX / Java Applet

I need webpage coded in C# that will be able to get a client mac address which will be used as part of a database query (where macADD = 'hklhllh') I currently have an active x component which works fine but that restricts what browsers can access the app, this query is part of a login procedure. I need a solution that will work with a mac also as well as other browsers not only internet explorer. If my explanation is not clear, I can explain in much greater details if necessary.