I was moved to write this because the Torys have decided to get ISP’s to block porn at source. Despite it being technically, if not impossible then incredibly difficult and likely to cause more problems than it solves.

Which means it will be incredibly expensive, and let’s face it the ISP’s wont be paying extra; we will. It will also not block all inappropriate content, but will block a fair amount of innocent content. It will also mean that even those who will opt out (choosing instead the more sensible method of computer based filtering) will still have to pay.

There are many reasons why it wont work, and here are just a few.. yes, honestly, this massive post doesn’t actually cover it all.

Anatomy of a website

The domain is the address you type in.
Eg. http://www.google.com
This is actually separate to the website itself, which is why you can have multiple domain names pointed to the same site.

Say you wanted to block http://www.google.com you wouldn’t necessarily be blocking access to the website itself. As they could then just set up http://www.googleisback.com without having to change where it is hosted or reload content.

You also could block domain names with keywords in the title, say you blocked “google”, however this wouldn’t block http://www.gooogle.com – which could easily be pointed at the same site.

So that wouldn’t work for filtering websites, too easy to get around.

A website is hosted on rented or bought server space, you could block the IP address for a server, which is what the domain name points to. This is about the only way to block websites, but requires you individually blocking each website.

An ISP provides access to the internet, whether for a user or server, some have their own servers which they host sites on. But not all do. Hosting and providing net access are two different things.

Essentially the same as the domain name, but with directions to specific pages or files.
Eg. http://www.mumsnet.com/Talk

You could block specific pages within a website, either by keyword or knowing the address. However you’d have to somehow take into account embedded information;
The web standard style of coding websites nowadays usually runs along the lines of;
Main page
¬ Header
¬ Content
¬ Footer

So while you may have blocked “main page”, you haven’t blocked “header”, “content” and “footer”, and if someone was to direct link to one of them..

Meta Data
Hidden information coded into webpages, usually keywords and a description. Not all sites bother with this though.

So although you could search the meta data for keywords and block pages where the meta keywords are to be filtered, if someone hasn’t entered meta data then the computer will have no way of knowing.

Keywords could also be in the coding. This will include the text you see on the page. You could block pages with blocked keywords, however, read on to see why that is flawed.

There are only two way to block images.
1) Block any images that are inserted using the [ img ] code. Which will block 99% of images. 99% of all images that is. Including the MN logo at the top of your page.
2) Block images with filtered keywords, but this has the same problem as meta data, it doesn’t have to be filled in. And the image file could be 111111.jpg. With no keyword data, you have no clue of that is a pornographic image or a pretty little flower.

There is no technology that exists that can identify what an unlabelled, generically titled image is either.

Embedded Media
Exactly the same as Images. This covers embedded video, interactive flash and audio.

Different filtering methods

You could block keywords. But what keywords would you block for porn?

Penis? Vagina? Breast?
– there goes any website that mentions anatomy in any way, say medical websites…

– so no personal pages about Ginger the cat.

Porn? Erotica?
– There goes this page, and a large part of the feminism forum.

Do any of you have spam filters on your email? Does that work all of the time?
Do you ever get emails asking if you’d like to purchase v1agra?

That’s the other way to get round keyword filters, just type things wrong or leave sp aces in them. You could even add in sym|3ols.

Also, if you wanted text but didn’t want it searchable then you’d just use an image file with the text on and not label the image file. Easy.

So to summarise. You can block individual IP addresses, one by one – but hang on, how would you implement this? Who’d decide? Do you create a central agency to decide? Or do you leave it up to the public to report?

If you leave it up to the public do you immediately filter any reported sites to look at when someone gets a chance? Or do you wait? Could get a few complaints when sites aren’t removed promptly enough? Say you decide that you will only filter a site when it has a set number of complaints? What happens when a large group of internet users decide it would be amusing to all report one site at once?

And would you block the page with the content, or the whole site? What if someone posted a pornographic picture on flickr, do you filter all of flickr?

If you use keywords to block sites then you will block innocent websites.

There’s also a flaw with opting in. Say it’s a family network, (because remember, the ISP’s can’t distinguish between separate computers) and one person wants to opt in (possibly because the filter system has blocked a website which isn’t actually pornographic) then how do you protect the children?? Oh yeah, a computer based filter. One which can be set up not only for individual computers, but also for individual user accounts on one computer. So essentially despite having a hugely expensive system put in place, the one that is likely to be the most useful is the system which is already in place.

Advantages to ISP filtering

– Parents who do not take note of what their children have access to, and who do not feel the need to censor internet access, will be be over ridden therefore looking after the poor innocent children. 
Uh.. well.. maybe.. that is as long as those parents don’t then opt out of the ISP filtering..

Ok, scrap that. Let’s start again..

Advantages to ISP filtering

Well.. um.. nope, coming up blank.

Advantages to Computer based filtering

– Customisable for different users. This means that you do not have to apply the same filtering to an entire household, you don’t even have to apply it to all users on one computer. Unlike ISP side filtering, which will be on or off for all users. So you may want to access something, but not want your child to access it. Easily done with a computer filter.

– Does not slow down the internet.

– Will not add anything extra to your monthly bill

– There are already free programs out there.


I can’t believe I actually need to write this, but going by previous conversations I obviously do.

I do not believe children should have access to porn, I am not upset that I would not be able to access porn.

I am however realistic about how technology works, and if someone could come up with a definitive way to stop children accessing all porn online I would support it wholeheartedly. But this isn’t it.

Why spend the money trying to make something work which is already known to be flawed, when that money could go into something which does help!

Is this really about blocking porn from kids? Because it obviously wont. You can either block all porn – by blocking basically everything, just in case. Or only some. Because if you decide the latter, what are you actually achieving?