We have blocked certain (guess what kind
websites on our corporate net, but now people just use external proxy servers to access them.
Is there any way to detect/disable that, with iptables only?
We have NATed network with only port 80, 443 allowed to be forwarded to web, and aren't using and own proxy server, but still it is possible to use external proxy or even a simple php page on remote server to forward and display blocked website to clients on local net.
Do we need to install squid or similar to be able to block some sites or even that won't help?