[arch-general] Can a ISP modify incoming http traffic to display ads using transparent proxy server ?

[Jan de Groot]

On Sat, 2011-04-02 at 12:15 +0530, Partha Chowdhury wrote:
> My ISP is running a transparent proxy server on port 80 as I found out 
> from this thread
> 
> http://mailman.archlinux.org/pipermail/arch-general/2011-March/019172.html
> 
> Now from last two or three days, I keep getting pop-up ads from a 
> particular domain on every website i go to - even on text only websites 
> ! If i choose another proxy server in firefox , then that does not 
> appear on any site. But i normally connect to internet, that specific 
> pop-up to a very particular website appears on every single page. If I 
> install adblock plus in firefox, then of course no ads are displayed.
> 
> So is it possible that my ISP is serving that ad by intercepting 
> incoming http traffic ?

Yes, proxyservers can intercept pages and modify them. I used to have a
transparent squid proxy that would filter ads and replace them with a
1x1px transparent pixel.
If you're paying for this internet line, I would suggest to switch to a
different provider. Inserting ads in HTTP pages for a connection that is
being payed for is not-done.