From owner-freebsd-questions@FreeBSD.ORG Mon Jun 23 20:36:36 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id DF5591065672 for ; Mon, 23 Jun 2008 20:36:36 +0000 (UTC) (envelope-from af300wsm@gmail.com) Received: from py-out-1112.google.com (py-out-1112.google.com [64.233.166.178]) by mx1.freebsd.org (Postfix) with ESMTP id 8F0E68FC18 for ; Mon, 23 Jun 2008 20:36:36 +0000 (UTC) (envelope-from af300wsm@gmail.com) Received: by py-out-1112.google.com with SMTP id p76so1106522pyb.10 for ; Mon, 23 Jun 2008 13:36:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:cc:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=CQAm0mlyo212m3SGCbYS9VEwF4HHPQ2EGuKbID1QdPM=; b=ugqxV76Ib4awhq8zlXW7dhysa1G3wlRsqVoYrEATlelmPcOI6lbIEJaikpmNzhT4dH 80zwiDZMstoZtInkKnd98GcHKJ3bAocEG+mcf53CKRKegDlH7Q0VitdAQyyExHCtdITT vFk4FklCYWRN4mIbo71trGplwvdeH5GzjLiQU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=D5FO+NVIankc93hR9vAwc0mlJ/e9T1WU9A8GRFXUXi6+YeJLp3ZA9ARlnwYiU8nLNm KwlUDpZyI6lFEm9rquKCKVFPy3sC1lACkF03aNd7qaqjn+mQoiG0zvGWwEbasCgLzYfE DKJ3yKOMIl0aNllmwr33fbit6DFkC74iF8mdo= Received: by 10.142.186.9 with SMTP id j9mr4486225wff.284.1214253395227; Mon, 23 Jun 2008 13:36:35 -0700 (PDT) Received: by 10.150.196.13 with HTTP; Mon, 23 Jun 2008 13:36:35 -0700 (PDT) Message-ID: <340a29540806231336g4be401a6h5f5a1b2b6dca110e@mail.gmail.com> Date: Mon, 23 Jun 2008 14:36:35 -0600 From: "Andrew Falanga" To: "Roland Smith" In-Reply-To: <20080623202259.GB97202@slackbox.xs4all.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <340a29540806231257x670cf398qc5bf11c396fd0afb@mail.gmail.com> <20080623202259.GB97202@slackbox.xs4all.nl> Cc: FreeBSD Questions Subject: Re: Wipe a drive clean X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 23 Jun 2008 20:36:37 -0000 On Mon, Jun 23, 2008 at 2:23 PM, Roland Smith wrote: > > I'm not sure about flash memory, but for a harddrive, simple writing 0's > is not a secure way to delete data. It can still be recovered. Actually, this is for an experiment that I want to start with a "clean" device for. I'm not actually trying to obtain some level of security. > >> I'd rather not install a port, if I can avoid it. I > > Have a look at security/wipe. Before reading this, yes I did. In fact, I even installed it. However, the first operation appears to be a renaming of the file in question. I was doing: wipe -z /dev/da2 which was being kicked out with "Operation not permitted." It seemed to want to move/rename the file first. I didn't do enough digging to get around this before reading this e-mail. > > > I think the trick is to use the right block size. Try bs=512 or > 2048 in your dd command. Use if=/dev/random instead of if=/dev/zero and > repeat a couple of times. Note that wiping flash drives way will > shorten the lifespan of the device. > The man page says that a block size of 512 is the default, though I put it on the command line anyway (talk about being paranoid). My problem was the input file. I was using /dev/null instead of /dev/zero (which I didn't know about until this e-mail). Thanks guys. Andy -- A: Because it messes up the order in which people normally read text. Q: Why is it such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet and in e-mail?