How to block access to some sites?

Question

Computer networks

How to block access to some sites?
Organization: 40 PCs (Win 7, 8 / 8.1) The employee brings his laptop (Win 7) and connects via cable to the hub that is in their room. I gave him an IP from our network. All other employees (except bosses) have programs for blocking access to certain sites and social networks, some are blocked through the hosts file. How to block this employee with a laptop so that at home he can go to the same social networks and watch whatever he wants?
Here's what's on the gateway. It seems that these sites are blocked. but it doesn't actually happen

thank you

Answer 1

1. For good, such things are done on the gateway - through a firewall / proxy and what else can you think of.
2. You do not have a sharashka office for 4 managers, 4 bosses and Bukh / Sysadmin - although I also raised the gateway in such a one and from there I already ruled everything.
3. Is everything so bad with you that people are forced to bring their laptops? The first thing I would do when I come to an organization where they give a patch cord to the first person I meet is to pump out 1c and internal customer databases / documents. Then I would sell to competitors. Yes, I am like that =)
Let them sit at home with their laptops and play zouma / farm / one-eyed people, etc. there. At work, there are jobs and "laws" of information security. Not fig.
And yes. Raising OpenVPN does not interfere with anything - hesitate to block through hosts

Answer 2

You initially crookedly made control of access to the Internet. What is the gateway?