Ubuntu: block access sites through internet gateway

Question

We have a local server which manages our internet connection. This server functions as a gateway, and that way we share the internet throughout the office (instead of using a router). However, I'd like to block access to the internet for all users at some point in the day, EXCEPT for a few websites. I do not care to doing this switch manually, but I'm looking for some easy method of blocking all but a few websites. Is there an easy way, with this server already centralizing internet access?

Answer 1

I have used squidguard before which has worked very well - supports blocking of sites and categories by specified rules(before work/lunchtime/weekends etc) and IP subnets. Once you have squid installed and working it is very easy to get squidguard in place. Permitting internal users by subnets is great for allowing access according to your organisational requirements.

Answer 2

A tool like dansgaurdian should be able to do this for you. You could also look at the custom filter capabilities of squid.

Answer 3

I realize that this may not be what you are interested in, but consider trying Untangle Firewall/Router, which is based on Debian, and indirectly Ubuntu, and allows all sorts of filtering. It is a great product for the kind of environment you describe.