How do you determine which adapter is used?

Question

I have a need to figure out which adapter is used when a connection is created. In other words, if I have multiple NIC cards (ie wireless, lan, etc) on my machine, which card is being used for the connection?

If anyone can point me in the right direction...

Answer 1

In C#

foreach(var nic in NetworkInterface.GetAllNetworkInterfaces.Where(n => n.OperationalStatus == OperationStatus.UP)
{
    if(nic.GetIsNetworkAvailable())
    {
       //nic is attached to some form of network
    }
}

VB .NET

ForEach nic in NetworkInterface.GetAllNetworkInterfaces.Where(Function(n) n.OperationalStatus = OperationStatus.UP)
    If nic.GetIsNetworkAvailable() Then
       //nic is attached to some form of network
    End If
Next

This will only test active working Network Interfaces that are connected to an active network.

Answer 2

你为什么不使用MAC地址？

Answer 3

Maybe you could map it by the MAC Address:

var nics = NetworkInterface.GetAllNetworkInterfaces();
foreach (var nic in nics)
{
    if (nic.OperationalStatus == OperationalStatus.Up)
    {
        var mac = nic.GetPhysicalAddress().ToString();
        if (mac == "your:connections:mac:address")
        {
            /* ... */
        }
    }
}

The "your:connections:mac:address" part you can figure out following this method, using the IP address of the LocalEndPoint .

How do I obtain the physical (MAC) address of an IP address using C#?

It's not beautiful, but it could work.