Making an ext3 partition unmountable (intentionally)

Jérôme Petazzoni jp at
Wed Aug 12 12:48:34 UTC 2009

Sri S wrote:
> Hello,
> I’d like to make an ext3 partition that cannot be mounted easily on 
> another system. I don’t want to use loop-aes to encrypt the partition 
> because of the performance hit. I also don’t need it to be very 
> secure, I just need to prevent someone from taking the drive from my 
> system and reading the data off of it.
> I was thinking about one or a combination of one of options:
>    1. Changing the partition’s ext3 magic number to some other magic
>       number that only I recognize
>    2. Changing the location of the super-block and backup super blocks

Maybe you could simply use a loop-device with the "offset" option.
It would be trivial to mount the partition (one would just have to issue 
the correct options to mount and/or losetup), but recognizing the 
beginning of the filesystem and guessing the correct offset would 
require some (minimal) knowledge about EXT3 layout.


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