Secure Overwrite of Free Disk Space

[Peter B]

Is there a Linux Program that will overwrite free disk space in a secure manner?
Or maybe a Terminal equivalent to the Windows Cypher /w: command?
For instance, after installing Linux Lite over the top of Windows, can the remaining free space be securely wiped and encrypted to ensure any 'leftover' files or documents from previous installations are inaccessible?

[rijnsma]

Maybe?:

Repository says:

Zerofree finds the unallocated blocks with non-zero value content in
an ext2, ext3 or ext4 file-system and fills them with zeroes
(zerofree can also work with another value than zero). This is mostly
useful if the device on which this file-system resides is a disk
image. In this case, depending on the type of disk image, a secondary
utility may be able to reduce the size of the disk image after
zerofree has been run. Zerofree requires the file-system to be
unmounted or mounted read-only.

The usual way to achieve the same result (zeroing the unused
blocks) is to run "dd" do create a file full of zeroes that takes up
the entire free space on the drive, and then delete this file. This
has many disadvantages, which zerofree alleviates:
* it is slow;
* it makes the disk image (temporarily) grow to its maximal extent;
* it (temporarily) uses all free space on the disk, so other
  concurrent write actions may fail.

Zerofree has been written to be run from GNU/Linux systems installed
as guest OSes inside a virtual machine. If this is not your case, you
almost certainly don't need this package. (One other use case would
be to erase sensitive data a little bit more securely than with a
simple "rm").

Or?:

Gutmann method based tools for securely wiping data from files, free
disk space, swap and memory: srm, sfill, sswap and sdmem.

[Scott(0)]

Is there a Linux Program that will overwrite free disk space in a secure manner?

I use BleachBit occasionally (LL108/64) and have never had a problem. You can find it in Synaptic.

[Peter B]

Scott

I installed BleachBit and ran the 'Wipe Free Space' routine - all seemed to go well until the progress message hung at 'Please wait. Wiping Free Space. about 0 minutes remaining.'
After leaving it for a further couple of hours, expecting perhaps a 'cleaning complete' message, still no change and then the Program wouldn't close down, I had to shutdown the computer to clear it.

[Scott(0)]

Have you tried the BleachBit website (bleachbit.sourceforge.net)? Looks pretty good. They also have forum. I only looked at it briefly but I see a forum post BleachBit not working on Ubuntu 14.04 LTS (assuming you're using LL2.0).

[Peter B]

I'd checked the BleachBit forum previously and couldn't find a match to my particular problem.
However, there seems to be Version 1.2 now available on their site and there is mention of free disk space clean-up problems listed as bugs fixed in this latest release.
But Version 1.2 isn't showing as being available via Synaptics (it's showing the latest version as being 1.01) and I have no idea how I might download and install 1.2 independently.

[Scott(0)]

Hi Peter. Have you posted your problem in the BleachBit fourm? I wish I had more answers for you but I'm just not that familiar with the software. 

[Peter B]

Hi Scott

I was planning to post in the BleachBit Forum later today, but because of their mention of bug fixes in Version 1.2 regarding Free Space wiping, I wondered if it was worth downloading it and installing it manually?

However, I've never installed a Program other than by using the standard update methods within Linux Lite, so I've no idea how to do it, or even if it's possible without risking damage.

[Peter B]

Update...

I downloaded and installed Version 1.2 and that seems to work properly now.

Thank you for your assistance.

[elliott]

secure-delete also seems to come with a feature to wipe free space. i used a sudo apt command to install bleachbit and it installed 1.0, i was curious if where you found the new version and if it does not crash when you run the "deep scan" features, this happens everytime for me. any luck? glad you figured it out, hoping i can figure out the same. i get a lot of "permission denied" errors even when i run bleachbit (as root), it will not allow me to wipe free space a long with other features that are locked....