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 (i.e. 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.