From owner-freebsd-security Thu Nov 18 13:58:27 1999 Delivered-To: freebsd-security@freebsd.org Received: from ind.alcatel.com (postal.xylan.com [208.8.0.248]) by hub.freebsd.org (Postfix) with ESMTP id 9645A154AD; Thu, 18 Nov 1999 13:58:21 -0800 (PST) (envelope-from wes@softweyr.com) Received: from mailhub.xylan.com (mailhub [198.206.181.70]) by ind.alcatel.com (8.9.3+Sun/8.9.1 (ind.alcatel.com 3.0 [OUT])) with SMTP id NAA21159; Thu, 18 Nov 1999 13:57:18 -0800 (PST) X-Origination-Site: Received: from omni.xylan.com by mailhub.xylan.com (SMI-8.6/SMI-SVR4 (mailhub 2.1 [HUB])) id NAA03618; Thu, 18 Nov 1999 13:57:17 -0800 Received: from softweyr.com (dyn0.utah.xylan.com) by omni.xylan.com (4.1/SMI-4.1 (xylan engr [SPOOL])) id AA22659; Thu, 18 Nov 99 13:57:14 PST Message-Id: <38347633.22E76DE0@softweyr.com> Date: Thu, 18 Nov 1999 14:57:07 -0700 From: Wes Peters Organization: Softweyr LLC X-Mailer: Mozilla 4.7 [en] (X11; U; FreeBSD 3.1-RELEASE i386) X-Accept-Language: en Mime-Version: 1.0 To: Barrett Richardson Cc: Kris Kennaway , TrouBle , David G Andersen , freebsd-security@FreeBSD.ORG Subject: Re: secure filesystem wiping References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Barrett Richardson wrote: > > On Wed, 17 Nov 1999, Kris Kennaway wrote: > > > On Thu, 18 Nov 1999, TrouBle wrote: > > > > > obliterate only wipes the one file you specify.. i want to wipe all the > > > free space on the disk, without damaging good intact files on it, linux > > > has a progrtam called wipe that does this, now ill ask again is there > > > something similiar for freebsd > > > > dd if=/dev/zero of=/usr/bigfile || rm -f /usr/bigfile > > > > Replace /dev/zero with /dev/urandom according to taste. > > > > Kris > > > > Excellant idea, and simple. The problem with modern encoding formats > is that the previous layer is still somewhat recoverable, and sometimes > layers before that. The obliterate program overwrites with carefully > chosen patterns intended to obscure the residual stray magnetic fields > left by previously written data. > > A file that big will be a problem for obliterate though, it'll have to > be done in strips. I've tested obliterate on some rather large files (250 MB) and it exhausts the system entropy pool very quickly, even on a system with a busy network. Does anyone make a hardware entropy device? ;^) -- "Where am I, and what am I doing in this handbasket?" Wes Peters Softweyr LLC wes@softweyr.com http://softweyr.com/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message