Thursday, December 6, 2018

Great Firewall of China breaking the threeway handshake?

So long time lurker but first time poster. And forgive the format, I am on mobile.

I work at an MSP and recently a customer's site was blocked on main land China. And I have researched how China normally blocked traffic with dns poisoning and ip blocking but that does not mesh with what we are seeing.

From China icmp traffic passes, but when trying to complete the three way handshake we see the SYN from China, we send the SYN-Ack then the connection times out.

Is anyone familiar with China use of this blocking?



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