HN user

kotri

96 karma
Posts1
Comments10
View on HN

ignore the forged RST+ACK

See <Ignoring the Great Firewall of China> in 2006. That won't work if RST/ACK was injected to both sides.

Then it would come testing to see if sending a bunch of ACK packets, perhaps with sequence numbers that would when reconstructed could complete the handshake. Trying to send them alongside the SYN+ACK or even before if it can be predicted. Maybe try sending some packets with sequence id 0 as well to see what happens.

This is an interesting approach already being utilized, namely TCB desync. But currently most people tend to buy VPN/proxy services rather than studying this.

How is traffic controlled inside PRC?

Unknown. I haven't seen any injected fake DNS or reset packets so far to domestic hosts. But there are rumors that Google's servers in Beijing (AS24424) was once black holed.

Is GFW a central hub for all traffic between all hosts?

It's supposed to has centralized management system, but not a single hub.

Or between residential ASNs and commercial ones only?

Yes, the injecting devices are deployed in IXPs, the AS borders. See <Internet censorship in China: Where does the filtering occur?>.

In the UK and Iran a lot of censorship was implemented by leaning on ISPs at IP level (eg BT Cleanfeed) and with DNS blocks but I haven’t kept up to date with how networks might handle residential hosting.

I believe Iran has more centralized system like China controlled by Tehran.

Maybe internal traffic is just all banned?

No, internal HTTPS traffic is not banned in that hour.