How to Block a Website Using a Firewall
A firewall is a program that can be used to manage incoming and outgoing connections from your computer to a network or the Internet. Though a firewall is mainly used to block (or allow) specific programs from connecting to the Internet, you can also use firewalls to block users from being able to access specific Internet pages. You just have to enter your firewall's "Settings" utility and manually add a rule disabling users from visiting a particular site.
Open your firewall's configuration utility. Steps to do this will vary depending on your specific firewall. For example, if you use the Windows Firewall (a permanent fixture of Windows XP, Windows Vista and Windows 7), you would enter the Windows Control Panel and open the "Windows Firewall" icon.
Select the "Settings" option in your firewall configuration utility. Some firewalls may call this the "Options" or even "Configure" menu option. This will bring up a list of programs and sites that are currently blocked from access, as well as a list of programs and sites that are currently allowed access to your network connection.
Select the "Add" button and add the URL of the website you don't want users of your computer to be able to access.
Click "OK." The URL of the website will appear on the list on screen and that website will be blocked from access on your computer by the firewall.