You could beef up the router and get one to control and monitor packets (data coming in and out) You can see who's accessing social networks an etc. Block IP or Web Sites you don't want these 9 systems to access. Another way is to block the sites through Group Policy or use one PC as
Kerio Control Web Filter
Kerio Control Web Filter service prevents users from visiting websites that are known to contain malicious content, including viruses, spyware, Trojans, or web pages that engage in phishing attacks or online identity theft.
Kerio Control Web Filter, integrated as a security service in Kerio Control, organizes sites into 141 different categories of web content. Administrators block or log access to sites based on specific content categories.
http://www.kerio.com/control/user-management/web-filter
Kerio Control Statistics
Network statistics
and user-based reporting
http://www.kerio.com/control/user-ma...tics-reporting