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 Posted by Bone Ur on 12/19/07 01:42 
Well bust mah britches and call me cheeky, on Tue, 18 Dec 2007 16:33:55 
GMT jw88574@hooya.com scribed:  
 
> Using Apache on an old PIII with Knoppix 
>  
> I am playing with a captcha image builder on my personal site and it 
> works pretty good.  It builds an image on the fly in var/www/pictures 
> and hands the actual code to a cgi script. 
>  
> But, the image it makes can be seen by anybody just by surfing to 
> http://somehost/pictures. So putting a security feature in the 
> document root is probably not a good idea.  Changing the path to build 
> the image to /usr/lib/cgi-bin/pictures solves the visiblity problem 
> but the HTML code that the cgi-script makes does not have the 
> authority to see the new location. 
>  
> So it comes down to my not understanding the security of web scripts 
> well enough. 
>  
> As I understand it, on this Apache the user comes in as user www-data. 
> The ownership and group to ./cgi-bin/pictures is www-data.  I think 
> this is true because if the cgi-scripts aren't owned by www-data, they 
> can't won't run.   But some of the documentation says that an Apache 
> user always comes in as unknown and I haven't resolved this issue yet, 
> like why would user unknown be allowed to run a script, rather than be 
> escorted to /dev/null. 
>  
> After thinking about it, it would seem that by giving a world visible 
> HTML script the rights to see an image, whereever it is, it would be 
> impossible to keep that surfer from seeing the image in the raw, so to 
> speak.  To put it another way, is there a method to allow an HTML 
> script in the document root to see and image (or file or whatever) and 
> still prevent access to that resource? 
 
Depends on exactly what you mean by "access". 
 
Regarding this image for instance, how would someone see it now without  
using your page? 
 
--  
Bone Ur 
Cavemen have formidable pheromones.
 
  
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