How to allow access to web only through proxy?

Question

I have a machine with Linux Slackware 13.37. Is it possible to configure iptables, so the users will be able to access web only through squid? The direct access through the browser will be blocked.

Cause I don't want them to visit certain sites.

Answer 1

Yes, but you will need to setup a white list of allowed connection,

Set default out going policy to drop, and only allow access to a specific port / server, i.e

iptables -P OUTPUT DROP
iptables -A OUTPUT -p tcp --dport XX -d YY -j ACCEPT
... ( your other rules )

That way user must configure their browser to utilize YY:XX as the proxy server.