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Re: Block directory authorities, is it possible?

I wonder if it's just an oversight that tor.eff.org hasn't been blocked
in your case?

I don't think it is an oversight that tor.eff.org has not been blocked in my case. I have never heard of the Tor site being blocked anywhere in China. My friends in Beijing, Shanghai and Shandong province are able to access it and I was able to access it continuously for three years in Shandong when I lived there.

How does the blocking with your ISP work? Do you get a generic reject
page telling you the service is blocked? Do you get TCP resets?

When a page is blocked it usually looks like it has timed out. I'm not clear as to how the blocking works. It seems that sensitive keywords in a webpage trigger the firewall to send a TCP reset to both the client and the server(1), but I do not know how specific IP addresses are blocked. I guess the routers at the great firewall just stop the client's request from reaching the server at that specific IP address and that the router at the firewall doesn't send any response back to the client so that it looks like a timeout. Someone please correct me if I'm wrong about this.

(1) http://www.andrewlih.com/blog/2006/06/27/great-firewall-filtering-revealed/

Kevin S.