[Gllug] Wiping free space.

general_email at technicalbloke.com general_email at technicalbloke.com
Tue Dec 29 18:29:24 UTC 2009

JLMS wrote:
> On Mon, Dec 28, 2009 at 4:27 PM, general_email at technicalbloke.com
> <general_email at technicalbloke.com> wrote:
>> b) AFAIK, files are block aligned so files which don't divide perfectly
>> into the block size may have space at the very end of that the OS
>> doesn't regard as free.
>> Are the above conerns legitimate or just here-say? If the former are
>> there any apps I would find in the big 3 repos that overwrite unused
>> space while mitigating the above?
> My main concern would be why to do all this at all.
> If the data is so sensitive then backup your file systems, clean the
> disk properly (using DBAN or something similar) or destroy it (if it
> is old you can get a cheap replacement easily, if it is new, it will
> cost you relatively little to get a newer, bigger disk), and recover
> your system from the backups.

I agree in most use cases there is a better alternative such as whole
disk encryption and offline wiping a la dban. I was just curious if this
can be accomplished in place to a reasonable degree too. Scrub
(mentioned by RJ earlier, thanks :) seems good enough to prevent
recovery of files and their names on non-journaled filesystems, although
it does not clean any journal data. Although that might still leave a
fair chunk of data that digital forensics analysts could retrieve
evidence from it looks good enough for day to day privacy on systems
where encryption / full disk wiping isn't an option.


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