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Some websites are blocked in my network, so I have to use a proxy outside my local network to access them. In order to maximize the speed, only blocked sites be accessed through proxy.

Currently, my browser(with a plugin named SwitchySharp) is doing the job of unlocking the blocked sites. However, it would be much better if a proxy server, which determines whether the requested sites are blocked or not, could do the work.

I don't know if I'm understood. The diagram below expresses the same idea.

Browser || Local Proxy: If the requested URL is in black list, then use a proxy outside the network to access it. If not, go for it directly.

I am in China, where a lot of websites are blocked. If there is such software, life can be much better: once the proxy is set, phones, tablets, laptops etc. can suddenly access all the world wide web has to offer.

I am asking this because if there isn't such thing, I will write one myself.

Thank you for reading this. Best regards.

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migrated from Dec 26 '12 at 9:05

This question came from our site for professional and enthusiast programmers.

You can use Proxy Automatic Configuration (PAC) files to achieve this.

The configuration is inside the IE: Internet Options / LAN settings / Automatic configuration

For example: I can use file://c:/test.pacinside the address (below "Use automatic configuration script")

And here is the example of test.pac content:

function FindProxyForURL(url, host)
if (url == "")
return "DIRECT";
return "PROXY";

For more syntax about pac file, you can refer:

Note: The automatic configuration script's address can not only be file://, it can also be http://, thus it provide more convenient way for management.

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Thank you. Actually, what I want is a proxy server that could parse PAC-like file. Guess I'll have to write one myself then~ – strongwillow Dec 26 '12 at 15:35

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