It isn't passive. See lines 64-73 of the code [1]. This seems very similar to what you describe, but rather than you pinging a bunch of places around the world, it has a bunch of places around the world essentially pinging you.
If you check the HTML source, it's src'ing scripts from machines around the world (I assume whatever host is being used, the author has spun up a VPN in each of their data centers). Here's an example of one [2]. Each of these sends you a constant value over and over again, and the server side measures the latency, before finally reporting the average round-trip time to you.
If you check the HTML source, it's src'ing scripts from machines around the world (I assume whatever host is being used, the author has spun up a VPN in each of their data centers). Here's an example of one [2]. Each of these sends you a constant value over and over again, and the server side measures the latency, before finally reporting the average round-trip time to you.
[1]: http://geoloc.foremski.pl/tcpinfo.go
[2]: http://46.101.226.53/DE_Frankfurt.js