This looks like apks and no desktop apps, is that accurate? I’ll never forget the warm cozy feeling I got when my isp sent me a letter listing the the movies I had pirated over popcorn time.
How did that work? Did they monitor the swarms? Fingerprint the chunks?
You can query trackers and DHT for torrents, and they return a bunch of IPs that are seeding/downloading the torrent. And then, as an ISP, you can combine IPs to subscriptions.
Check out this website that does the IP querying part for you:
Wow! I never thought there were records of that.
There’s a Defcon talk circa 2013 about crawling DHTs: https://www.youtube.com/watch?v=cvQrNoCwxgE
There's also magnetico: http://magnetico.org/
"Autonomous (self-hosted) BitTorrent DHT search engine suite."