anti-ad blocking (anti-leech) system?

[Spinball]

Hi Folks,
I would like to block access to our website by all people who block adverts.
Not pop-ups - just normal ad banners.
(The ad banners on our site pay for it's existance and I would like to address the problem of people using ad blocking. I use an ad serving system I wrote myself which involves an external php script to determine what banners to serve etc.)
I see a couple of threads here relating to anti-leech but they focus on stopping file downloads.
Is there a way to do it?
Thanks.

[Deaths]

Is there a way to block ads? Banners I mean.

You could maybe insert some vital code into the ad code, so if they block the ad the forums are all messed up :)

[Marco van Herwaarden]

A quick and maybe simple solution would be to show a generated code along with the banner ad. If someone want to download something, they should enter that code. Seems like the simplest and easiest way to do it.

[Deaths]

Doesn't he want them to not be able to look at the site entirely?

Maybe you can use a query for this.
Basicly, when they see the banner, some field in the user's User field will be altered from 0 to 1. And every time they want to see the forums, vB checks for that field, if it's 1 or 0. If it's 0, it returns an error.

[AN-net]

i dont believe this is possible without some heavy coding which is probably more work than just simply not using popups/ads or just not worry about it. this probably require some type of java etc. since anti-ad programs are OS programs not web programs so.... yeah... you would need to find a coder for this

[Reeve of shinra]

Have the advert itself leave a cookie thats needed to view the site? I dont know.

Honestly, if users are viewing your ads, then you need to start offering something different that your users would be more inclined to participate in. Treat the problem, not the symptom.

[Spinball]

I think this issue will affect a lot of vB users since many of us rely on advertising for the survival of our sites.
MarcoH64 - interesting solution. Makes life a bit more complicated for regular users, though.
Deaths - yes - I want the system to try and serve a banner and if it fails, a different page opens explainaing why they are not allowed to access the site.
AN-net - we reply on advertising to pay the very large running costs of the site. I have written a proprietory php ad serving script which I could edit if I knew how to test whether they have ad blocking on or off.
Common sense tells me that the web server is instructed not to serve the graphic and text which are identified as an advert. The fact that this has happened must surely be detectable?
Reeve of shinra - what about people who are not using cookies? Stuffs the site up for them, too?
Thanks all for your replies.
My fingers are still crossed that someone knows a solution.

Is there a way to block ads? Banners I mean.

You could maybe insert some vital code into the ad code, so if they block the ad the forums are all messed up :)

Actually I guess it might be possible to have the default style show black text on a black background, and have the proper forum style override this and embedded in the banner? Does anyone know how to do this?

[Zero Tolerance]

I suppose the easiest solution would to be insert the Ad(s) inside an object, like:
<div id='AdObject'>ADS GO HERE</div>

Then use a little bit of javascript to detect if the ad is there or not .. and then if not, js will redirect them to a page saying bla bla bla.

What types of ad's are you using, if i can look at them i can show you how to implement this method.

- Zero Tolerance

[Spinball]

<a href="http://www.avforums.com" target="_blank">www.avforums.com</a>
They are gifs, jpgs, swfs or Google Adsense.
You'll see the 468x60 ads served at the top (run of site) and the 728x90 which appear at the top and bottom of specific forums and all the threads in them.
The Google adverts are the 'house ads' displayed by default. The plasmas forum has lots of adverts in it.
I already enclose them all in a div to center them and I've put in an id as you suggested.

Thinking about it, perhaps the best way to approach the problem would, rather than block the pages altogether, maybe have a Javascript alert pop up infront of every page asking them to switch of ad blocking.
If they also have Javascript switched off, then I guess we're stuffed?

Appreciate any help you can give to encourage people to add us to their 'allowed sites' list.

[Spinball]

Zero Tolerance seems to have disappeared (?!).
Ok, I implemented a solution where a div tag is put around the advert and put the following Javascript after it:

<script type="text/javascript"> <!--
if (document.getElementById('AdObject')=null)
{
var nagtext='<H3 align="center">Nag message.<br>Thank you.</H3>';
document.write(nagtext);
}
//--> </script>


and installed AdSubtract software to block adverts. My solution above failed because AdSubtract adds

style='text-decoration: none'

at the end of the IMG tag of the banner.

Anyone know how to detect the text-decoration setting of an element? If I could detect that I could also display the nag message.