Re: [debian-knoppix] Include wipe into Knoppix
Am Freitag, 1. November 2002 14:55 schrieb Klaus Knopper:
> Hello Christian,
>
> Sorry, I'm not going to include wipe, because it's useless.
Since with wipe I'm able to securely destroy sensible data with one simple
command (i.e. wipe -r /path/to/sensible/data) I think, wipe is definitely not
useless. :)
> We had this discussion before, but I'm summarizing it anyways. ;-)
Thank you very much. :)
> Depending on which filesystem you use, erasing a file by copying random
> data over it is not going to physically destroy the file contents on
> your harddisk. Journaling filesystems for example create new blocks
> when you overwrite a file, rather than overwriting existing ones. So,
> even doing a dd if=/dev/urandom of=file_to_be_shred (which is what wipe
> does), does not necessarily do what you expect.
I always thought wipe does not only writes several times random data over the
data to be wiped out. I understood this tool, as it would write some special
patterns in a special sequence, so that the possibility of getting old data
out of the effect of the magnetical remanence, is decreased more than just
writing random patterns. But I'm open to other explanations. :)
Another 'problem' is that if I want to overwrite a file with dd i need to say
dd the size of the wile. wipe deals that automatically.
> Concerning tapes: use dd. it is faster and present on every Unix
> installation.
What I have to do here is to securely delete sensible data in only a few
directories (usually /home/<data> and /usr/local/<data>) with together about
one or two gigs of data on some computers when for example the harddisks are
getting more and more badblocks and needs to be replaced, the computer goes
to another division in our institute or the computer is sorted out and
donated to a school or similar.
The easiest way would be to boot those computers with KNOPPIX, mount the
partitions, run a "sudo wipe -r /mnt/partition/sensible/data", wait for half
an hour or so and that's it. If i had to run several write cycles with random
data on the entire disk, this would last much longer than only wiping the
sensible data itself.
The problem ist, that I don't have network on those maschine when I delete
these files, so that I could simplay download the tool over the net and
floppy drives are also unuseable in that situation I had to experience
(defective floppies, floppy drives, floppy controllers or even there is no
floppy drive available).
Regards,
Christian
--
Christian Wenke
OFFIS
Bereich Embedded Systems
Escherweg 2 - 26121 Oldenburg - Germany
E-Mail: christian.wenke@offis.de - URL: http://www.offis.de/
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