How to Setup Encrypted Filesystems and Swap Space Using ‘Cryptsetup’ Tool in Linux – Part 3

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Gabriel Cánepa

Gabriel Cánepa is a GNU/Linux sysadmin and web developer from Villa Mercedes, San Luis, Argentina. He works for a worldwide leading consumer product company and takes great pleasure in using FOSS tools to increase productivity in all areas of his daily work.

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16 Responses

  1. Artem says:

    yum update??? I think it’s not good idea to do that. apt-get update and yum update are different things.

    • Gabriel A. Cánepa says:

      Who said they were the same? Doing a yum update before installing a package in a CentOS system is a matter of personal preference. I also use to do aptitude update for a different reason, yes – but again it’s also a personal preference.

  2. Edward Arawiran says:

    I tried to execute the command cryptsetup –version but it only results in
    cryptsetup 1.6.6. I am using Ubuntu 16.0.4 Server version. Did I miss anything>?

  3. Ansil H says:

    Hi ,

    I’ve managed to get the encrypted swap auto mounted in OpenSuSE 13.2 (not secure as we use a key from from local system.Prefer to use interactive setup at boot )

    * cruptsetup luksFormat /dev/
    * dd if=/dev/urandom of=/etc/en_key bs=1024 count=4
    * cryptsetup luksAddKey /dev/ /etc/en_key
    * en_swap /dev/ /etc/en_key swap # in /etc/crypttab
    * /dev/mapper/en_swap swap swap sw,pri=1 0 0 # in /etc/fstab
    * Enable verbose logging at boot (/etc/default/grub – GRUB_CMDLINE_LINUX_DEFAULT=”….. splash=verbose loglevel=3″)

  4. toshiro says:

    Did you test what you wrote on a real server? The instructions to setup a encrypted swap partition don’t work at all (at least in Ubuntu). Also, it’s not clear how do you create the encrypted device in the case of the swap partition, do you use a passphrase? what happens when you use /dev/urandom in /etc/crypttab?

    • @toshiro,
      Yes, I did test what I wrote on a real server. As you can see in the screenshots, I used a box named dev2 which was a Debian Wheezy 7.5 system. You use a passphrase to encrypt / decrypt a partition, as explained in this article. Such passphrase is not used to encrypt / decrypt the swap partition, but you need to create a separate one for that (or you can make it the same – it’s entirely up to you). As for the use of /dev/urandom in /etc/crypttab, you can refer to man crypttab here:

  5. Christopher Adigun says:

    Please is “Encryptin the Swap Space” part of the LFCE blueprint? The blueprint seems a bit loose or did you just decided to add swap aspect?


  6. Matt P says:

    There is an an area I found to be unclear that caused me hours of headache. In item one of the swap file encryption section the instructions indicate “and encrypt it as explained earlier'” I was never able to get the swap file to mount on reboot because of the luks format pass phrase. A helpful addition to the article may be to explain the difference between a plain dm_crypt and luks format. It took some trial and error once I figured out that difference, but instructions 2-4 in the swap file setup work flawlessly once the concept of plain encryption is understood.

  7. Frank Costanza says:

    Spelling mistake – cryptesetup

  8. derrend says:

    Great series of articles, wish I’d found them earlier :)
    “Configure systems to mount standard, encrypted and network file systems on demand” is one of the listed competencies on the LF’s website but I’m a little confused about what is meant by that and I notice you don’t show an fstab entry for the newly created encrypted partition. Is this intentional?

  9. '@Gabriel A. Cánepa says:

    Thank you for your comment. You are correct in that you mention yet another setup alternative for file sustem encryption but please note that LVM is out of the scope of the LFCE requirents.

  10. I personally prefer LVM v2 under LUKS encrypted disk space. I have used this for may years now.

    The thing to be carefull about is the partion ids being used. Particularly x’85’ for your extended partion – keeps Windows away – and x’FC’ – as stated on the man page – for your encrypted data.

    Something else, I regularly trip over is the diferences between implementations of LVM. particularly, -M or fixed node numbers. The same is true with extfs(4). NB: The man page has dropped the description of –major, but it is still required with -M, but is ignored.

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