Distributions of Linux that include some form of Flash Player browser extension as part of their package system usually allows external Web access to typeface configuration data. Debian, Fedora and the various *Buntu releases generally ship a customized NPAPI-compliant Flash interface. Other users may have installed their own version of say Firefox or QupZilla and therefore might be unconsciously transmitting font information.
This information is transmitted with the intent of helping Web developers find out more about which fonts are installed on what types of devices, but it should generally be viewed as a problem because it’s inefficient as well as insecure. Chances are if you’re running Linux, then you probably lack many of the fonts installed on Android, iOS, OS X and Windows devices, thus rendering this technology pointless to begin with. Fortunately it’s very easy to disable if you know the right place to put a configuration file.
Disabling Flash Font Enumeration
First open up a graphical command prompt by either holding down CTRL and ALT while pressing T or selecting the icon from your desktop environment’s root menu, depending on which distribution you’re using.
Issue the following command to move to the right directory:
This is where the file needs to be. Should the cd command fail, then type:
You’ll need to enter your password if prompted. Issue the command:
This will return mms.cfg if the file is there. If other files are there or nothing at all, then you won’t need to worry about anything and can simply move on. If the file is already there, then proceed to the next step, but be sure to not change anything else in the file.
Type sudo nano mms.cfg at the command prompt and press enter. You’ll be brought to a text editor screen where you’ll need to add the line
DisableDeviceFontEnumeration = 1
Hold CTRL and press O, then press y to save the file. Hold CTRL and press X to exit the nano text editor. You may want to logout of your desktop environment or restart to make sure the changes took.