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Windows 8.1 has native EXT4 mounting abilities?!


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#1 Guest_AnonVendetta_*

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Posted 09 August 2016 - 09:20 AM

First, I'm sure the answer to this question is a definitive "no". Windows has never been able to natively mount Linux filesystems. But I ran into a strange thing today:

 

I created a container in VeraCrypt (improved TrueCrypt clone) in Linux, and formatted its' filesystem as EXT4. A container in this respect is essentially a disk contained within a file. My intent was to store files/directories in it that have characters that are not possible in Windows. VeraCrypt warned that mounting the container in Windows would result in Windows not being able to recognize the filesystem without a proper driver, and prompting to format.

 

So, I installed VC and Ext2Fsd in Windows. Then I mounted the container after authenticating. To my surprise, Windows immediately assigned a drive letter to the volume within the container, and the contents are plainly visible in Explorer. I even right-clicked the drive letter and went to Properties, Windows clearly lists the filesystem as EXT4.

 

At first I thought Ext2Fsd might have assigned a drive letter, but the container doesnt appear as a disk in either Ext2Fsd or Disk Management.

 

I'm baffled, how is this possible? The only explanation I can think of is that either Windows 8.1 has native EXT4 mounting abilities, or Ext2Fsd assigned a letter but isn't showing me anything. Can someone possibly follow my steps to see if this can be duplicated? Can you also try with only VC but without installing Ext2Fsd?

 

Thanks!

 

Edit: I'm tempted to think that this is the work of VC (as of v1.17 or earlier), that it somehow has a EXT4 driver built into it that Windows can access:

 

As an example I cannot assign a drive letter to my Fedora root volume in Disk Management (which is a real volume on a real disk, not a VC container), but I can manually assign a letter to it with Ext2Fsd (and it appears as a volume there along with the correct size), only then can I access the contents.

 

I thoroughly cleaned my PC of these 2 programs (both files and Registry), rebooted, then mounted the container in a portable copy of VeraCrypt. My PC was running in a so-called "shadow mode" via Shadow Defender, which is a software that transparently redirects all changes to a selected volume into RAM, any changes are gone after reboot. I got the same results outlined above, except this time Ext2Fsd wasn't present. The volume within the container doesn't appear in Disk Management, either as a disk or as a volume, and neither does the container, they also aren't listed in diskpart.



#2 karyonix

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Posted 09 August 2016 - 10:44 AM

VeraCrypt assigns drive letter to its volumes, so no other program have to do it again.
Ext2Fsd allows access to directories and files in EXT4 formatted volume.
These 2 are enough.

Ext2Mgr is drive letter assignment utility which is a different program from the file system driver of Ext2Fsd.
It is provided together because Windows does not assign drive letter automatically for EXT4 formatted disk volume.
Ext2Mgr is made to list some know types of volumes (disk, cdrom).
It is understandable that it does not know about some volume other kind (e.g. VeraCrypt volume) even if Ext2Fsd works with them.
Ext2Mgr is not needed for VeraCrypt volume because it already has drive letter assigned by VeraCrypt, so there is no problem.

Disk Management is just user interface to deal with disks. It does not do anything without user action. And it does not see non-disk volumes.

#3 Guest_AnonVendetta_*

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Posted 11 August 2016 - 04:14 AM

@karyonix: Thanks for the info. I had begun to believe (after initial testing) that VC and not Ext2Fsd was the cause of my EXT4 volumes being assigned letters. Since Ext2Fsd is not needed for my purpose, I'm thinking that VC must also have some kind of EXT4 driver integrated that is able to make my volume accessible to Windows.

 

In regards to your last paragraph, a "non-disk volume" makes no sense to me. A volume/partition doesn't constitute an entire disk, they lie within a disk. Many use the terms volume and partition interchangeably, my understanding is that a partition is generally raw unless formatted with a filesystem, called a volume, whereas volumes tend to have filesystems. A volume lies within a partition, but a partition generally doesn't lie within a volume and isn't a volume per se. Maybe I'm wrong, someone can correct me if they want.

 

I found this on Wikipedia:

 

https://en.wikipedia...e_and_partition

 

It points out things like (as examples):

 

1. "A floppy disk might be accessible as a volume, even though it does not contain a partition, as floppy disks cannot be partitioned with most modern computer software".

 

2. "Another example occurs in the Intel world with the "Extended Partition". While these are partitions, they cannot contain a filesystem directly. Instead, "logical drives" (aka volumes) must be created within them".

 

And:

 

"In short, volumes exist at the logical OS level, and partitions exist at the physical, media specific level. Sometimes there is a one-to-one correspondence, but this is not guaranteed".

 

3. "In Microsoft Windows Server 2008 and onward the term "volume" is used as a superset that includes "partition" as well".

 

4. "It isn't uncommon to see a volume packed into a single file. Examples include ISO9660 disc images (CD/DVD images, commonly called "ISOs"), and installer volumes for Mac OS X (DMGs). As these volumes are files which reside within another volume, they certainly are not partitions".



#4 Wonko the Sane

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Posted 11 August 2016 - 09:17 AM

Well we have a long thread dedicated largely at those definitions:
http://reboot.pro/to...ach-to-booting/
JFYI:
http://reboot.pro/to...e-6#entry123056

Though there is the common exception of NTFS (cannot remember if since Windows 2000 or Windows XP), as when it comes to NTFS in a partition, the volume/filesystem and the partition are not exactly the same thing (they differ by one sector), the partition contains the volume/filesystem + the NTFS bootsector mirror, and there is the issue with "volume or filesystem" slack:
http://reboot.pro/to...ated-with-dsfo/
http://www.forensicf...ewtopic/t=9374/

:duff:
Wonko




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