"unidentifiable mechanism" I'm not sure this is actually true. You can determine that it is a VPN by checking the amount of exchanged packets between interval

"unidentifiable mechanism" I'm not sure this is actually true. You can determine that it is a VPN by checking the amount of exchanged packets between interval of time (e.g. if 5 kbps are routinely sent every 30 seconds for 5 minutes this is totally abnormal) Another alternative for the government could be to limit the bandwidth and time of hosts who have a big standard deviation in the amount of the packets per second they transmit. So undetectable I don't think so and I believe smarter people here can find even better ideas. That being said it's a very nice tool, certainly useful in corporate environments as well (except of course, that it'll be suspicious that one single host is exchanging so much data and keeping so long connections)