My application use Web-service. I'm control from what workstation was request and for this send MAC-Address how parameter of all methods. But then I start testing application in real, I found workstations which have many network adapters - Ethernet, Wireless, Bluetooth. When I get MAC-address using next code:

var networkAdapters = NetworkInterface.GetAllNetworkInterfaces();
if (networkAdapters == null || networkAdapters.Length == 0)
    return string.Empty;

string address = string.Empty;

foreach (var adapter in networkAdapters)
{
    var a = adapter.GetPhysicalAddress();
    if (a != null && a.ToString() != string.Empty)
    {
        address = a.ToString();
        break;
    }
}
return address;

Sometimes Web-service receive from workstation different MAC-Addresses, but I want get always only one MAC-address. Please, help me.