Date: Mon, 23 Jun 2008 14:36:35 -0600 From: "Andrew Falanga" <af300wsm@gmail.com> To: "Roland Smith" <rsmith@xs4all.nl> Cc: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: Wipe a drive clean Message-ID: <340a29540806231336g4be401a6h5f5a1b2b6dca110e@mail.gmail.com> In-Reply-To: <20080623202259.GB97202@slackbox.xs4all.nl> References: <340a29540806231257x670cf398qc5bf11c396fd0afb@mail.gmail.com> <20080623202259.GB97202@slackbox.xs4all.nl>
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On Mon, Jun 23, 2008 at 2:23 PM, Roland Smith <rsmith@xs4all.nl> 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?
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