On my local network I have to setup Linux Ubuntu boxes, so users will be able to access only to few (2-3) domains. Also, all of those Linux Ubuntu boxes are behind Proxy.
Tried to configure this using Firestarter, but I did not make it after several hours of attempts.
Most of the time, I was able to access to all of Internet, or wasn't at all - in Firefox I was getting the message:
The proxy server is refusing connections.
IP address of Proxy server is 192.168.21.155.
What I tried with Firestarter is to define Outbound traffic policy as Restrictive by default => whitelist traffic => Allow connections to host: 192.168.21.155,
and several IP addresses I want to give access. But no luck, all of the websites where blocked in this case.
Also, tried to Allow service DNS (port 53), and Http-alt (port 8080) to several IP addresses I want to give access.
But I did not make it.
Also, I removed UFW (Uncomplicated Firewall) with all of it's definition, and on Iptables I have no rule defined.
Can you help me please how to configure firewall in this case?