When a venue is set up, it inherits a list of default categories to restrict. Each category contains a list of sites that will become inaccessible.
Every website request made through a Purple WiFi session is routed via our DNS filtering servers. These servers check against the list of blocked sites and the IWF watchlist. If a User request is denied, it redirects them to a landing page explaining that access to this site has been blocked.
These lists are configurable either by the Internet Watch Foundation's watchlist, by category (for instance bars will usually want to remove alcohol related sites from the blocked list) or by specific site.