My pen drive is very important to me. I have a 32GB one, with Ubuntu 12.04 on it. On then pen drive, I created two partitions; one ext4 for Ubuntu (5GB) and the other partition is fat32, so that windows can access it too, with restrictions.

Windows users without my permission can't see nor modify anything in my fat32 partition. However, when I boot from my pen drive and log in with guest account, I can see the fat32 partition and do whatever with it, delete it if i want.

I just want to restrict access to that particular pen drive (only for the guest account). I also don't want to disable the guest account, because if somebody boots from my pen drive and just want to check mail or save an image from the Internet to their own pen drive, they need to be able to see/mount their pen drive.

  • possible duplicate of How do I prevent standard users from using the USB ports? – Mitch Aug 1 '12 at 8:46
  • @Fresco I dont understand yoor question, you have Ubuntu installed on your HD in a partition (I assume this has a guest account) And you have Ubuntu installed on your pen drive. Is it just you using the pen drive? The source of my confusion is if you want to restrict other from accessing the pen drive allow them to login as guest on the HD install and put the pen drive in your pocket. Am i missing something? – stephenmyall Aug 1 '12 at 13:08
  • I currently don't own any computer, since I like Ubuntu because it's fast, i have my own settings wherever i go, etc... When there's a free computer I shut it down and start booting from my pen drive. Now if someone steels my pen drive, they can boot, enter guest and start to rifle trough my files on the fat32 partition, i just want to deny guest account that privilege, but only for my fat32 partition, because if guest users have their own drive, of course i let them use it! As for windows, i assured it's hidden and nobody can see nor modify anything in my partition, the only weaknes is guest. – Fresco Aug 2 '12 at 8:08

It is important to understand that these permissions are only enforced when the version of ubuntu on the pen drive is running. If I were to connect this pen drive to another computer I would be able to read any data on the pen drive, regardless of the permissions set in the file system.

If someone else has physical access to the pen drive, only encryption of the contents will give you any protection. (Note that this applies to a desktop computer too - if someone has physical access then they can remove the hard disk and examine its entire contents on another machine, or boot from their own USB stick - the operating system only enforces permissions on files when it is running).

You might want to look at a cross-platform encryption tool like TrueCrypt to store your data.

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Select contains of your drive. right click on it choose permissions. You can remove or give permission for data to any user or you also for read, write or execution of your data.

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  • This doesn't work. – Fresco Aug 1 '12 at 12:45


The link allows you to disable the guest access feature in Ubuntu to such that you could prevent access. You are good to go now...

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  • Welcome to Ask Ubuntu! Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference. – Warren Hill Nov 23 '13 at 14:49

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