We hear time and time again of countries censoring internet traffic by blocking IP Ranges.
Without getting into the politics of it, let's take for example China's Great Firewall. Even though it is not the most oppressive of firewalls, it still seems to be a constant cat-and-mouse game of VPN server's IP addresses getting blocked and VPN hosting companies moving to different IPs. When technologies altogether such as OpenVPN get blocked, modifications are made to the protocol to allow the traffic to pass undetected.
With so much effort going into maintaining these firewalls, it might almost be worthwhile to create a list of every legitimate service IP that is used. Has a government ever experimented with whitelist-based censorship?