I’m trying to bind a socket in .NET to a specific network interface. Looking at the IOControlCode documentation, I can see that I could use BindToInterface (SIO_INDEX_BIND) or UnicastInterface (SIO_UCAST_IF) paired with the IOControl method for that. However, when I try using any of those options, I get the following exception:

System.Net.Sockets.SocketException: 'The attempted operation is not supported for the type of object referenced'

I tried looking for documentation online on how to use those options, but found nothing useful. Can someone enlighten me on how to use them properly?

PS: I don’t want to use the Bind method on my socket because it binds to a specific IP address, and I need to bind my socket to a network interface instead. I’m running my code on Windows 11 OS.

I tried binding the socket with the following code:

var uri = new Uri("http://example.com");
// Create and connect a dual-stack socket
Socket socket = new Socket(SocketType.Stream, System.Net.Sockets.ProtocolType.Tcp);
// Interface index is 7
socket.IOControl(IOControlCode.BindToInterface, BitConverter.GetBytes(7), null);
socket.Connect(uri.Host, 80);

But got the exception mentioned above. I was expecting it to work and to bind the socket to the interface.