[37785] in bugtraq
Re: *nix data wipe tools
daemon@ATHENA.MIT.EDU (Wietse Venema)
Fri Dec 17 14:54:28 2004
In-Reply-To: <41C1EAAF.9050203@edeca.net> "from David Cannings at Dec 16, 2004
08:06:07 pm"
To: bugtraq@securityfocus.com
Date: Fri, 17 Dec 2004 13:05:37 -0500 (EST)
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From: wietse@porcupine.org (Wietse Venema)
David Cannings:
> Thomas C. Greene wrote:
> > I've posted the final versions of a few simple, free shell scripts that i've
> > been working on to make data hygiene more convenient on *nix systems. Thanks
> > to list members who helped test them and contributed improvements.
>
> Is there any specific advantage of these scripts over bcwipe?
>
> http://www.jetico.com/index.htm#/bcwipe_unix.htm
There's a general problem with applications that go through the
file system to destroy the contents of a file. Unless one uses
very simplistic disk harware and file systems, there is no guarantee
that overwrite requests will actually overwrite the intended bits.
For a example, Solaris 10 ZFS uses copy-on-write, to avoid corruption
when the system crashes in the middle of an update; many disk drives
have write caches built-in so only the last overwrite request takes
effect; and non-volatile memory "disks" have a limited number of
write cycles and try to avoid hot spots.
Wietse
