Squid is a tool that has caching features and a built-in proxy server. This helps you to redirect the http traffic to that proxy server and cache it. By redirecting to the proxy server and serving the web pages from the cache, lot of bandwidth is saved. It is simple and effective to use squid and it is free.

You can find it in Red Hat Linux or Fedora operating system. Check it out whether squid is running in your system by typing the command ‘rpm –q squid’ in the command prompt.

With squid running you can restrict the users from accessing any particular IP address which means that you can restrict them from accessing any websites. You can also restrict by mentioning the website name instead of the IP address.

You can also restrict the users by the day and the time of access. You can also use regular expressions to match any of the text entered in the address bar and restrict them if the URL has a particular string.