Understanding Your Thin Client | 13
All attacks on the terminal's security or unwanted changes can be thwarted by
simply rebooting the machine if the filter is turned on. Operating the machine
with the Filter turned off can be dangerous to the terminal and the important OS
files inside it.
Introduction to FBWF
The File-Based Write Filter, more commonly referred to as the FBWF, is a an
intelligent filtering system that allows you to protect specific volumes of your
local drive from write access, while simultaneously keeping less important files
like anti-virus databases or a user's
Documents and Settings
folder persistent.
The FBWF allows users to decide which directories are persistent and which are
transient. Persistent files are files that are not protected by the FBWF filter, and
all changes, good or bad, will survive after rebooting. Transient files are files
that are protected by the FBWF filter and all changes that are made to these files
are neglected and forgotten upon rebooting the terminal.
How Does FBWF Work?
When the FBWF is enabled, it makes your files secure from that instance.
Rebooting the terminal will revert your system immediately back to the state it
was in when you enabled it, like a restore point. As long as your FBWF is
enabled, it is in a safe state. It stays safe because it writes all changes made on
the system on an
overlay
in the RAM memory cache. An overlay can be
thought of as a protective layer over the disk. All changes made to the disk are
written on the transparent layer instead of the actual disk. When the terminal
looks for information on the disk, all upgrades and new installs can be found and
accessed because it is written on the overlay which is covering the disk.
However, once the terminal is rebooted, the memory cache is erased, and the
overlay is wiped clean, with no changes made. The system automatically
resumes from the same point it was at when you enabled the filter.
To install new hardware and software, or to upgrade any existing programs or
applications on your system, you will have to disable the FBWF. It is important
to re-enable the File-Based Write Filter as soon as the installation is complete so
you can protect your terminal from unnecessary disk writes. As long as you are
not installing or upgrading, it is necessary to leave the File-Based Write Filter in
an enabled state for correct performance. As long as it is enabled, your terminal
is safe from malicious network attacks or accidental uninstalls.
