The paper describes how to mitigate eavesdropping:
> Changing the fiber adapter connecting to the modem from a flat PC end face to an angled APC end face can reduce the echo, which is also a practical method to avoid the risk of being eavesdropped.
> Changing the fiber adapter connecting to the modem from a flat PC end face to an angled APC end face can reduce the echo, which is also a practical method to avoid the risk of being eavesdropped.