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Thread: Command Line to wipe a hard drive

  1. #1
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    Question Command Line to wipe a hard drive

    Is there a nice list of command lines somewhere. New at this and the command lines I've attempted are not getting me anywhere. Need to wipe a hard drive.
    Thanks in advance.

  2. #2
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    Quote Originally Posted by Seabean1 View Post
    Need to wipe a hard drive.
    Hi Seabean1 and welcome to the Knoppix forums.

    No reply ? Perhaps what you are asking is not what you need. I think most reading your post will say to themselves "Anyone who knows what they are doing would not have to ask how to do something so dangerous". There certainly isn't a nice command line that is guaranteed not to wipe the wrong hard drive for you.

    Could you tell a little of what you are trying to achieve or what has gone wrong for you ?

    Usually it is enough to repartition your disk and create new file systems. Wiping the hard drive is something you'd only need to do you've confidential data or naughty pictures on the drive you really need to destroy. There's special disk wiping software available for that.

    You sure it's a hard drive 'cos flash drives are different. You sure it the whole drive and not just a partition ?

  3. #3
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    Yes....I need to wipe the whole drive!

    Thank-you for your response. I work in a data center and I've been asked to wipe all hard drives before decommissioning a server. Normally, we have a service punch a hole in the drive, but this one device is being shipped out for reuse at another center. Thanks.

  4. #4
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    if you are REALLY certain you want data to be written over the entire disk I can give commands here that will do it fairly well.
    first I would like you to disconnect everything but that one drive and what you have Knoppix runing on, then write back here, yes I am serious
    one of the commands is called dd and this command will do a great job of overwriting the information on ANY disk.
    my command is actually several commands in sequence that will take a while to complete (we talk days with any large drive).
    fact is that some of it may actually still be recovered with some care after 10 repeats, clasified data on things like hospital computers require this to be repeated 25 times and to be treated as still not 100% clean.
    some authorities (read armed forces, intelligence community...) require disks with sensitive data to be incinerated at 1300C, by then the disk is a molten blob of metal waaaay beyond curie point.
    Curie point is the point where materials loose their magnetic properties and the domains are in free flux, even a bar of steel is not magnetic at that point (blacksmiths use that fact when they harden carbon or "low alloy" steel, at that point the steel is just few degrees below ideal hardening temperature)

  5. #5
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    I am using an old server and I'm booting from the CD with Knoppix. I have a total of 4 drives to wipe, but can do one at a time if necessary. Time is not an issue. And thanks.

  6. #6
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    ok, here goes, if you type wrong drive number you will wipe wrong drive beyond easy repair, so take care.
    first you become "superuser" or more correctly root.
    Code:
    sudo su
    everything you do from now is dangerous.
    first you find name of drive by typing
    Code:
    sudo  fdisk -l
    on a commandline.
    the outout wil be something like
    Disk /dev/sdb: 7948 MB, 7948206080 byte
    Enhet start end Block Id System
    /dev/sda1 * 11 19166 7757824 83 Linux
    (yeah I am using a pen-drive just now)

    this tell me that I have only one drive called sda and only one partition called 1

    a ATA drive would show up as hda for first drive, hdb for second, hdc for third...
    a SCSI or SATA drive would show up as sda for first drive, sdb for second, sdc for third...

    partitions are merely numbers 1, 2, 3...

    wiping the disk I write
    Code:
    dd if=/dev/urandom of=/dev/sda&&dd if=/dev/zero of=/dev/sda
    this wil first write "random" data to the entire drive bit by bit, in the process wrecking any partitiontable, filesystem... then it will write zero's to entire drive bit by bit (yeah, will take a while).

    if you just wanted data to be fairly well destroyed so you could start anew, here you go.

    if not enough, now for second step.
    make disk one large partition and encrypt entire drive, that is a bit more than I can write here, but here you have one link (search web for more, there is a lot out there).

    http://www.tldp.org/HOWTO/html_singl...ryption-HOWTO/

    Actually you could likely do it using RSA/SHA like if it was a textfile or E-mail.
    use sha or rsa on /dev/XYZ as if it was a file

    if you want a "deeper wipe" repeat ALL steps above 25 times/disk

    if you want data 100% gone you are out of luck as to simpel computer code, according to authorities only way to be 100% certain is if you melt them down and almost have to stir the thing according to some (not likely needed imho as the magnetic properties will be gone past curie point)
    Last edited by OErjan; 03-12-2011 at 07:58 AM.

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