About a month ago, the China Telecom here started blocking my DSL account from downloading web pages. One of their network techs told me they stopped allowing the sharing of a broadband line among multiple computers. Unfortunately, the heuristic that determines which connections are shared is too sensitive. I have triggered it several times with a single computer.

The times I've noticed, the block started around 5:10 am. My guess so far is that they are counting the number of http connections or the bandwidth used in a day or looking at the maximum number of concurrently open HTTP sockets in a day. One symptom is that connections to web pages get reset, which is an old great firewall trick. Another symptom is that these http connections get redirected to a "blocked" URL which strangely points at an unused IP address. This causes firefox to hang for a very long time. The only official recourse seems to be calling the China Telecom 10000 help line. They dutifully take a day or two to fix things.

Luckily I've been able to work around this so far both with tor and with ssh SOCKS.