Using free subdomains to circumvent web filtering systems

Question

(I was told that this was the place to ask this by someone from Webmasters, if I've got it wrong again please give me a chance!)

I'm running a personal proxy service for the use of myself and some of my friends. Currently, in order to circumvent filtering restrictions I've signed up with a free web host to use their subdomain and that works for now, but it's only a matter of time before that subdomain is blacklisted. Is there any way I can use the subdomains provided by a free DNS/subdomain provider (such as http://freedns.afraid.org) as fully featured domains to keep my site unblocked?

Answer 1

You can certainly make it so that people can use the free subdomain to reach your website. Whether that would actually circumvent filtering systems is a different story and will largely depend on how the filtering system works.

To allow people to access your website using the subdomain URL, you'd just register the subdomain you want, and they will ask you for the IP address you want it to point to. Of course, here you would enter the IP address of your web server.

If your website is the only site on the webserver, then this would probably be all you'd have to do. But if there are multiple sites on the server, you will need to add a VirtualServer entry for the subdomain in your webserver configuration so that the webserver knows which website users are trying to reach when they access the webserver's IP. If you are using shared hosting you can probably ask your hosting provider to do this for you.

But like I said earlier, whether this would actually circumvent filtering depends on how that filtering system works. If it filters based on domain name, then there's a good chance it would work, but if it filters based on IP address, it would do no good because your website will be at the same IP address no matter how many subdomains you register for it.

Answer 2

...Is there any way I can use the subdomains provided by a free DNS/subdomain provider (such as http://freedns.afraid.org) as fully featured domains to keep my site unblocked?

I assume you mean to have your own proxy at home and just have a static public host name for this proxy.

It depends what kind of block you are trying to circumvent and how you do it:

• Running a real web proxy or a SOCKS proxy can easily detected because the traffic looks very typical and different from normal HTTP traffic. Corporate firewalls can often be configured to detect and block this kind of traffic. They block this kind of traffic not by target URL but just by the traffic pattern, so using another hostname does not help.
• Running a forwarder which rewrites the URLs (e.g. rewrite http://example.org/foo to http://proxy.example.com/example.org/foo) is harder to detect. But it is a security risk because you effectively disable the protection by same origin policy if you are serving everything from the same domain. Even using a subdomain for each major domain (e.g. example.org.proxy.example.com/foo) would not be enough. And given enough traffic it might be detected because of unusual usage. But in this case it would be either by target host name or by IP address. In the first case using just another host name would work, in the second case the IP where you run the proxy service on is affected. A corporate network might also simply block all traffic to ISP for home users for security reasons (the IP ranges are known, so blocking is easy).
• Having a local proxy instead which translates your requests and then forwards them to your external proxy might help be restoring protection by same origin policy. Apart from that the same problem with possible detection applies.

In any case:

• If you tunnel only a few traffic inside a network with lots of other traffic the chance of detection is low, unless you use some easily detectable way like a HTTP proxy or SOCKS proxy.
• If you try to circumvent some policy this way and you will be detected, than you have to face the consequences. It does not matter if this is a corporate policy, school policy or state policy, although the consequences might be different.