Content Advisor Alternatives

I need help looking for an alternative to content advisor,

Right now we have 55 different offices connecting to our corporate location using VPN. We currently block all access to internet on remote locations, and anytime we need to add a site to the approve list, I have to connect to each computer and add the site manually.

I am looking for a way to redirect all traffic from our locations to a central server here in our corporate offices. I want to have one list of approved sites they can access and everything else block. That way when I want to add an approved site I just add it to our list. Is that possible? Any ideas?

Thanks!