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User's Manual


Koffix Blocker is a desktop application that helps you to block or restrict sites that are involved in questionable practices.

When you surf the web you may sometimes accidentally visit sites that, for example, try to install some sort of spyware on your computer. If you had known that beforehand you probably wouldn't have visited these sites at all. Koffix Blocker can help you block these sites.

To block a site, Koffix can simply add it to the HOSTS file. This type of block will stop all communication with the site and it will appear to you as if the site does not exists. Koffix can also restrict certain sites by adding them to the Restricted Zone, which in short put certain restrictions on the sites such as preventing the site from running ActiveX, JavaScript or installing files. You will still be able to browse the restricted web site.

You can find the complete list of sites included in Koffix on the official Koffix website.


Please download the setup file from the official web site, save it somewhere on your computer, double click the file to start the installation. The installation wizard will guide you through the installation.

Running Koffix

Once the installation is finished, you can run the program by clicking Start -> (All) programs -> Koffix Blocker-> Koffix. (The Start button is generally located in the bottom left corner on your desktop.)

Welcome screen

Screenshot of Koffix's welcome screen When Koffix starts it will show the "Welcome screen" with some general information about the program. To continue, press the "Start scan" button and Koffix will examine your system to see which sites that should be blocked.

Scan finished screen

Screenshot of Koffix showing the 'Scan finished screen' The scanning is usually finished in a blink of an eye, and you will see the "Scan finished screen" which shows a list of sites that you can block by putting them into the Restricted zone and/or the HOSTS file. You can get more details by clicking the » links or the sites-link to find out why a site is included in Koffix. Check the boxes of the sites you want to block, when finished, scroll down to the bottom and click "Apply selected changes", and the sites you have chosen will be blocked.

Updating Koffix

Please keep in mind that you can update koffix by pressing the UPDATES button in the Welcome screen. This will update the block definition file from If an update was available and successfully downloaded, remember to go through the process of scanning and selecting the sites you would like to block again.
When there has been a major upgrade of Koffix it will be required to uninstall the program and the download the new version. In such an event you will be notified in Koffix welcome screen.


You can uninstall Koffix from the "Add/Remove Programs" dialog accessible from the Windows Control Panel. If Koffix is running, please close it before starting the uninstall.
Please notice that the sites you have blocked will remain blocked after uninstalling Koffix.


An error occurred when trying to open the file for writing. Filename: 'C:\WINDOWS\System32\drivers\etc\HOSTS'. .. Access is denied

The "Access is denied" error occur if your HOSTS file is write-protected. There are a few anti-spyware programs - such as "Spyware Search and Destroy" and "WinPatrol" - that can write-protect the HOSTS file and prevent Koffix from modifying it. If you are running Spybot 1.4 you can remove the write-protection by the following sequence: Start SpyBot -> Mode -> Advanced Mode -> Yes -> Tools -> IE Tweaks -> Uncheck "Lock Hosts file read-only as protection against hijackers"

You can also remove the write-protection manually with the following sequence: Click Start -> (All) Programs -> Accessories -> Windows Explorer, then browse down to the HOSTS file (You can see the exact path of your HOSTS file in the error message displayed in Koffix). Right-click the HOSTS file, choose Properties, uncheck Read-only, click OK.