public static bool TryPortNumber(int port)
	{
		try
		{

			using (var client = new System.Net.Sockets.TcpClient(new System.Net.IPEndPoint(System.Net.IPAddress.Any, port)))
			{
				return true;
			}
		}
		catch (System.Net.Sockets.SocketException error)
		{
			if (error.SocketErrorCode == System.Net.Sockets.SocketError.AddressAlreadyInUse /* check this is the one you get */ )
				return false;
			/* unexpected error that we DON'T have handling for here */
			throw error;
		}
	}