Finding all local network broadcast addresses
foreach (NetworkInterface Interface in NetworkInterface.GetAllNetworkInterfaces())
        {
            if (Interface.SupportsMulticast)
            {
                IPInterfaceProperties IPProperties = Interface.GetIPProperties();
                foreach (IPAddressInformation  address in IPProperties.MulticastAddresses)
                {
                    Console.WriteLine(address.Address);
                }
            }
        }
    }