I've never really thought about this. Thanks for bringing it to my attention!
If they use the same port and protocol as most of the Internet (i.e. HTTPS on port 443), they're safe from this? Steem RPC does, so should be ok, whilst the RPC servers can stay afloat!
To shut that down, they'd have to turn off the Internet as we know it, or commandeer the DNS servers, which I think is their usual approach.
The attack surface is so big, that they can start from anywhere, if they really want. If you don't think this is possible, look at China and at their internet, which is basically a glorified intranet.
I've never looked into how China censor their 'Internet'. Do they not just block most cross gateway SSL connections, and do packet inspection on unencrypted traffic?
Much, much more complicated than that. I've been in Hong Kong a few years ago and exchanged a few tweets with a friend who was traveling with me but staying at a different hotel. The tweets arrived 2 days after we left HK. In order to pull this out you gotta have a lot more than just packet inspection (huge pipelines, storage management, etc). It's not called "the Great Wall of Internet" for nothing.
Right, yeah I suppose they have internal censorship too, so can't even use the same SSL as we do! A different world indeed!