Back in the day when every hotel that was charging for WiFi was stupidly leaving port 53 wide open, I wrote an IP over DNS tunnel to get free WiFi. Worked great until I went to a hotel in Tokyo and turned it on. Suddenly my network connection was completely dead. They were clearly watching for shenanigans. Took me a few minutes to figure out they had redirected my MAC address to the bit bucket. I spoofed my MAC to a different one, and then behaved, as well as admired those IT guys.

Yeah, back when I was in school it was a cat and mouse game of finding a new proxy every week when the last one got blocked. The minute someone found a new one, it was everywhere.

I decided to sidestep the whole game and run my own proxy at home. I didn't have enough bandwidth for multiple users, so it was just me. I don't think IT ever caught on.