$ curl -I filesonic.com

HTTP/1.1 302 Moved Temporarily
Server: nginx
Date: Sun, 17 Apr 2011 12:21:29 GMT
Content-Type: text/html
Location: http://www.filesonic.com/
Age: 0
Via: HTTP/1.1 webcache1-know.server.virginmedia.net (Traffic-Server/5.7.0-59705 [cMs f ])

几点：

1. The IWF are the quango who have taken it upon themselves to filter bits of the Internet in the UK. ISPs then subscribe to a list of blocked domains and individual URLs.

2. the IWF want to only block individual URLs. Unfortunately, this can only be done at the HTTP layer since URLs exist at this layer, which means its necessary to proxy all traffic through a HTTP proxy. This is done by your ISP routing any packets addressed to, say Fileserve’s IP address, to their own proxy instead of to Fileserve’s servers. Your ISP’s proxy then checks to see if the url is blocked. If it is, several different things may happen depending on your ISP. In some cases the connection is dropped. In others a 404 File Not Found (dishonest) or a 403 Forbidden (honest) is returned. If the URL isn’t blocked, the ISP’s proxy will make the request on your behalf to Fileserve and respond with Fileserve’s response.

3. IWF这货在2008年就跟wikipedia干上了。Scorpions的Virgin Killer又中枪了。

4. 当然，IWF官方也是很冠冕堂皇的说，我们只封XX内容。

我觉得这种ISP级别的全局代理是最贱的。天底下操蛋的东西都一个德行。

via