data shredder
Gilles Gravier
ggravier at fsfe.org
Mon Dec 21 08:08:58 UTC 2009
If you want to be sure your data gets shredded, use an encrypted
filesystem either through LOFI, or using Solaris' ZFS file system, or
some other full disk encryption tool.
On my Ubuntu Netbook, I use TrueCrypt : http://www.truecrypt.org/ which
is nice because it encrypts to a FAT filesystem... and the resulting
encrypted volumes can be shared with Windows or MacOS.
Deleting a file from an encrypted volume results in random data being
put there.
You can also look at projects like assured delete from my colleague
Radia Perlman : http://research.sun.com/techrep/2005/abstract-140.html
Gilles.
On 21/12/2009 08:26, Emil Payne wrote:
>
> NoOp wrote:
>
>> On 12/20/2009 07:28 PM, jesse stephen wrote:
>>
>>> I'm looking for a data shredder for ubuntu 9.10
>>>
>>>
>>>
>> $ man shred
>>
>>
>>
>>
>>
> From MAN SHRED - Note the info about EXT3:
>
> CAUTION: Note that shred relies on a very important assumption: that
> the file system overwrites data in place. This is the traditional way
> to do things, but many modern file system designs do not satisfy
> this assumption. The following are examples of file systems on
> which shred is not effective, or is not guaranteed to be effective
> in all file sys‐ tem modes:
>
> * log-structured or journaled file systems, such as those
> supplied with AIX and Solaris (and JFS, ReiserFS, XFS, Ext3, etc.)
>
> * file systems that write redundant data and carry on even if
> some writes fail, such as RAID-based file systems
>
> * file systems that make snapshots, such as Network
> Appliance's NFS server
>
> * file systems that cache in temporary locations, such as NFS
> version 3 clients
>
> * compressed file systems
>
> In the case of ext3 file systems, the above disclaimer
> applies (and shred is thus of limited effectiveness) only in
> data=journal mode, which journals file data in addition to just
> metadata. In both the data=ordered (default) and data=writeback modes,
> shred works as usual.
>
> Ext3 journaling modes can be changed by adding the
> data=something option to the mount options for a particular file
> system in the /etc/fstab file, as documented in the mount man page
> (man mount).
>
> In addition, file system backups and remote mirrors may contain
> copies of the file that cannot be removed, and that will allow a
> shredded file to be recovered later.
>
>
>
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