Integrating Home Assistant with FreshTomato allows you to track devices connected to a wireless router running FreshTomato firmware.
See this Home Assistant article for an example of how to configure a basic setup:
https://www.home-assistant.io/integrations/tomato/
The github page containing the Home Assistant source code for Tomato integration can be found here:
https://github.com/home-assistant/core/tree/dev/homeassistant/components/tomato