public static IPAddress GetDefaultGateway()
        {
            var card = NetworkInterface.GetAllNetworkInterfaces().FirstOrDefault();
            if (card == null) 
            {
                return null;
            }
            foreach (var address in card.GetIPProperties().GatewayAddresses)
            {
                if (address.Address.AddressFamily == AddressFamily.InterNetwork)
                {
                    return address.Address;
                }
            } 
            return card.GetIPProperties().GatewayAddresses.FirstOrDefault().Address;
        }