I think I used to wardrive around and add open wifi hotspots to that system when I was like 18/19. I had Linux on a laptop and had gotten a crazy wifi antenna and a USB GPS module (along with some less than legal software to crack WEP encryption) and would drive around in my van looking for routers I could hop onto and map which ones worked and had internet.
I’m not sure what map software I was using though. It was some open source thing.