Given all of the attention on the banning of Web sites in the UK (read Wikipedia / Scorpions album), we thought we’d give you the inside view on how it comes about.
If a member of the public raises an objection to a Web site to the Internet Watch Foundation (IWF), the IWF takes a look at it to judge if it’s objectionable (btw – they’re one of the few bodies in the UK legally allowed to view the child pr0n)
If the IWF condemned it, the Web address is passed over to the people operating the signed-up-ISPs.
The Web address is then resolved to IP address/es and uploaded to the ISP’s IP Filter and proxy servers that sit inside the networks of CleanFeed ISPs.
A User at home types in a domain name into their browser, the domain will resolve the IP and this is checked against the dodgy-IP list.
This request is then filtered over the to proxy where the full URL is passed for investigate further.
The full URL is passed or failed as being acceptable after it’s looked up on their banned URL list and, depending on the ISP, the user either sees the site if it’s been judged as OK, or if not, depending on their ISP, nothing is displayed on their Web browser but an error message.
If, for example, they’re with Demon Internet, they get a HTTP 403 error, letting them know that they’ve been forbidden from accessing the site.
If they’re with Virgin they just get a 404 error, as if the site was unavailable, so the Internet user is none the wiser that they’re tried to access a forbidden site.
Not all queries go through the proxy, as given the amount of traffic most ISPs handle, they’d melt, so the ‘check IP address’ first method works better.
All of this is logged at the ISP, but nothing happens with the data unless the police make a legal request for it.
That’s pretty much the sum of it.
Thanks to Steve Kennedy for the background on this.