/**
@page defender_demo AWS IoT Device Defender
@brief This demo demonstrates usage of the AWS IoT Device Defender Client library.

@section defender_demo_main AWS IoT Device Defender Demo
@brief This demo application uses the AWS IoT Device Defender Client library,
MQTT Client library, and JSON library to interact with the [AWS IoT Device
Defender service](https://aws.amazon.com/iot-device-defender/).

The demo reports the following metrics to the AWS IoT Device Defender Service:
- Network statistics [Packets (Ethernet Frames) and Bytes sent and received over wire]
- List of open TCP ports
- List of open UDP ports
- List of established connections

The demo gets the above metrics by reading `/proc/net/dev`, `/proc/net/tcp` and,
`/proc/net/udp`. It then constructs a JSON report in the format as expected by
the AWS IoT Device Defender service. The constructed JSON report is then
published on the device defender MQTT topic reserved for publishing JSON
reports. The demo then waits for a report accepted response, and ensures that
the response contains the same report Id as was sent in the request.

<div class="caption" style="text-align:center">
AWS IoT Device Defender Demo Workflow
</div>
@image html defender_demo.png width=100%
*/