like the other commenter said, they have IP address information which they "can" corelate from say logs from reddit and pin point which anonymous user posted something. or where a particular email was sent from, they find the email, they can trace it back to the sender and looking at logs, can find where and which device that was from.... ipv6 is very prevalent in india and you don't need a wifi AP level monitoring as you can do on a per-device basis