Guangzhou airport has a crazy way of providing free wifi. If you have a Chinese phone you can receive a login account via text, but if you don't have a Chinese number, then you have to go to a physical ticket machine, scan your passport, and quickly jot down (or photograph) the code that flashes on the screen for 15 seconds.
Once you have this code, you have to click "Ticket Cert" on the login page and enter the info.
This worked fine for me on my iPhone.
But when I tried to follow the same steps on my laptop, the "Ticket Cert" option did not appear on my browser login prompt. I saw a slightly different page that only had the SMS option (and a bunch of half-loaded CSS and javascript errors).
I tried many things including spoofing the UserAgent on my browser. Nothing seemed to work.
Finally, I changed the MAC address on my laptop to match my already-online iphone's
ifconfig en0 ether [iphone's "Wi-Fi Address"]
This worked.
PS: So far, I have not managed to get any sort of vpn, proxy or ssh tunnelling to work.