Serial port RS-232 and Security

Question

If I have a device connected to serial port RS-232 on my computer and an application that is communicating with it. How secure is this? Can another application communicate with the device at the same time or is is just possible for one application?

And if my application isn't running, can another application communicate with the device? If so, how can I protect other applications to not communicate with the device? Is there any security settings in Windows for this?

I can not change the behaviour of the device, and it has no password protection.

Answer 1

If your application is running and the port is open, no other applications will be able to read/write to/from the same port. But, if your application is not running, any other application will be able to open the port and to send data, commands to the device.

Answer 2

To add to ocsid80's answer, one solution to the security is to ensure that there is always a known program running that has connected to the serial port and hence locked out all other programs. As an example you could write a service/device driver that connects to the physical port on start up and acts as a proxy to the physical port. Then your desired application talks to this proxy as required and you can build in all the security you need to establish this link.