Many network adapters at machine, need to find one that is used for traffic in Windows (from .net)

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.E开发者_如何学运维mpty;

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.

---

If I had two different ethernet cards - two different MAC addresses - which MAC address would be the right address?

Answering that is the root of answering this question. You have to create the algorithm to pick the right choice - there are lots of tools at hand to enable you to be more discriminating:

1. GetIsNetworkAvailable==true - identifies only interfaces with active connections
2. Speed - enables you to probe for fastest connection
3. NetworkInterfaceType e.g. Ethernet

Even given these rules, multiple adapters may still match. e.g. a machine with multiple NICs bound to the same LAN. Only you can determine rules for tiebreakers.

---

You know what IP address your application is using for the Web service, right? Precisely one adapter will have this IP address.

Ypou can check this via GetIPProperties > UnicastAddresses