In order to block access to certain sites, edit the hosts file located at c:\windows\system32\drivers\etc\. This document contains the DNS names of banned resources, so placing him the addresses, you will prevent the visit unwanted websites from your computer. This mechanism is relevant only for one PC, and in that case, if a blocked site, there are mirrors, you must make an entry in the host e for each mirror individually.
Use the method of IP blocking. To do this, create a list of IP addresses of sites with illegal access to a specific computer, thus you will ensure the lock using the software firewall. However, this method to block a website by the name would be impossible. Do not forget about the method using the proxy server. The essence is to create "black lists" of sites in the software settings of the proxy server. When using this method, you indicate "stop words" in URLs, to which access want to close. The inferiority of this method is the forced browser setting and the ability of the users to visit the forbidden resources, bypassing the proxy server.
Also use method of URL filtering. Great flexibility and good effect of this method is very different from the previous one. The analysis of each network resource is the essence of the process URL filtering. If found, the header of the WEB request that contains the url of the site you want to block, it performs the following operations:

1) is blocked by the network resource with the client request;
2) the client sends a message "Access blocked";
3) terminates TCP connection.

To use this method to the value of the filter type prohibited requests and save the changes. URL filter can block access to any website by name, to prevent downloading the file by their extension and also create a list of approved sites and deny access to others.