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Old 04-25-2005, 12:14 AM   #1
atheist
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Completely Deleting Files (quickly)


I'll keep this quick.

I'm looking for a way to delete data from a hard drive. Three harddrives, simultaniously. One of which contains the operating system itself. A Debian GNU/Linux system. I need this to be in a way that doesn't allow for any kind of recovering of the data.

This preferably, has to be rather quick and non-complicated.

I've partioned the disks using xfs, reiserfs and ext2 (/boot/) along with swap space on each drive. So, every disk has multiple partitions.

I'd appreciate it if you could help me out.
 
Old 04-25-2005, 12:40 AM   #2
crozewski
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nothingnothing

Last edited by crozewski; 12-03-2008 at 10:58 PM.
 
Old 04-25-2005, 01:42 AM   #3
atheist
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Thanks. But here's a part of the man page:
Quote:
CAUTION: Note that shred relies on a very important assumption: that
the filesystem overwrites data in place. This is the traditional way
to do things, but many modern filesystem designs do not satisfy this
assumption. The following are examples of filesystems on which shred
is not effective:

* log-structured or journaled filesystems, such as those supplied with

AIX and Solaris (and JFS, ReiserFS, XFS, Ext3, etc.)
Which is not too good since I'm using only using ReiserFS and XFS. Not counting the 32MB /boot/ partition.
 
Old 04-25-2005, 02:29 AM   #4
jschiwal
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Before installing the system, you could boot up with a live distro, or your rescue system, and use the dd command to do manually what shred does, except use of=/dev/hda1 to shred the entire parition rather than working on individual files. Perhaps a simple script that first uses if=/dev/zero of=/dev/hda1, then uses if=/dev/random (use this a few times) and finally if=/dev/zero. You will need to remake the file-systems after you are done, or since all of the partitions are zeroed out, perhaps delete all of the partitions and install from scratch. The Norton Shred program for Windows goes over a file 3 times by default, while the shred command repeats the process 26 times by default.

If you have more than one hard drive, than you could run the scripts in the background for each one. However, if you have several partitions on a single hard-drive, running them in parallel would lead to drive head thrashing.

Another idea is to change the type of the partitions to ext2 and try to use shred on the entire partition, however I don't think that would work.

Last edited by jschiwal; 04-25-2005 at 02:34 AM.
 
Old 04-25-2005, 02:40 AM   #5
kencaz
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Thermite always works well when you need to destroy somthing fast.

Look into it.

KC
 
Old 04-25-2005, 02:57 PM   #6
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You could use Autoclave http://staff.washington.edu/jdlarios/autoclave/ which boots from a floppy and allows you to securly delete all partitions on a hard drive, you can even wipe more than one hard drive at a time.
 
Old 04-25-2005, 05:18 PM   #7
tormented_one
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A really powerful magnet will do the job. A bucket of salt water, or you can do like the company I work for and drill holes through the drives. If you wanna keep the drives, as for quick I can think of none, but dd, autoclave, shred, and a few others will work. Also, I cant help but think purge. I know my install of slack has no purge command, so I can't say if debian has a purge or comparible command. I personally would go with dd if=/dev/zero, if=/dev/random as stated above.
 
Old 04-26-2005, 02:56 AM   #8
atheist
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Thanks. I should be able to work something out with all that. I'm thinking http://dban.sourceforge.net/ right now. That's what was recommended on the Autoclave site, anyway.
 
Old 05-04-2005, 10:50 PM   #9
crozewski
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nothingnothing

Last edited by crozewski; 12-03-2008 at 10:59 PM.
 
Old 05-04-2005, 11:31 PM   #10
Tinkster
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None of the methods (thermite aside) are a) quick enough
or b) unrecoverable ... dban, wipe are too slow if you want
instantaneous; salt-water won't kill the magnetic surface but
only the electronics, so data can EASILY be recovered; drilling
holes will give you bad sectors, but data can STILL be recovered
from other areas of the drive.

A good load of thermite (or a good load of magnesium shavings
with some KmNO4 or NH2ClO4) with some reliable ignition method
will be the safest bet).

Cheers,
Tink
 
  


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