Neil
Neil
Treat your password like your toothbrush. Don’t let anybody else use it, and get a new one every six months.

Encrypted block devices Centos RHEL 8 easy

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Introduction

Disk encryption protects the data on a block device to be encrypted. To access the device’s decrypted contents, a user must provide a passphrase or key as authentication. It is essential for mobile computers and removable media. In addition, it helps protect the device’s contents even if it has been physically removed from the system. The LUKS format is a default implementation of block device encryption in RHEL.

The Linux Unified Key Setup-on-disk-format (LUKS) enables you to encrypt block devices, and it provides a set of tools that simplifies managing the encrypted devices. LUKS allows multiple user keys to decrypt a master key, which is used for the bulk encryption of the partition.


RHEL utilizes LUKS to perform block device encryption. By default, the option to encrypt the block device is unchecked during the installation. However, if you select the option to encrypt your disk, the system prompts you for a passphrase every time you boot the computer. This passphrase “unlocks” the bulk encryption key that decrypts your partition. If you choose to modify the default partition table, you can choose which partitions you want to encrypt. This is set in the partition table settings.

What LUKS does?

  • LUKS encrypts entire block devices and is well-suited for protecting mobile devices contents such as removable storage media or laptop disk drives.
  • The underlying contents of the encrypted block device are arbitrary, which makes it helpful in encrypting swap devices. This can also be useful with specific databases that use specially formatted block devices for data storage.
  • LUKS uses the existing device mapper kernel subsystem.
  • LUKS provides passphrase strengthening, which protects against dictionary attacks.
  • LUKS devices contain multiple key slots, allowing users to add backup keys or passphrases.

Install cryptsetup to the server

# dnf install cryptsetup -y
Last metadata expiration check: 0:07:52 ago on Sat 26 Feb 2022 12:58:23 PM UTC.
Dependencies resolved.
=======================================================================================================================
 Package                          Architecture            Version                        Repository               Size
=======================================================================================================================
Installing:
 cryptsetup                       x86_64                  2.3.3-4.el8                    baseos                  190 k
Upgrading:
 cryptsetup-libs                  x86_64                  2.3.3-4.el8                    baseos                  470 k

Transaction Summary
=======================================================================================================================
Install  1 Package
Upgrade  1 Package

Total download size: 660 k
Is this ok [y/N]:
Downloading Packages:
(1/2): cryptsetup-2.3.3-4.el8.x86_64.rpm                                                81 kB/s | 190 kB     00:02
(2/2): cryptsetup-libs-2.3.3-4.el8.x86_64.rpm                                          173 kB/s | 470 kB     00:02
-----------------------------------------------------------------------------------------------------------------------
Total                                                                                  242 kB/s | 660 kB     00:02
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                                                               1/1
  Upgrading        : cryptsetup-libs-2.3.3-4.el8.x86_64                                                            1/3
  Running scriptlet: cryptsetup-libs-2.3.3-4.el8.x86_64                                                            1/3
  Installing       : cryptsetup-2.3.3-4.el8.x86_64                                                                 2/3
  Cleanup          : cryptsetup-libs-2.3.3-2.el8.x86_64                                                            3/3
  Running scriptlet: cryptsetup-libs-2.3.3-2.el8.x86_64                                                            3/3
  Verifying        : cryptsetup-2.3.3-4.el8.x86_64                                                                 1/3
  Verifying        : cryptsetup-libs-2.3.3-4.el8.x86_64                                                            2/3
  Verifying        : cryptsetup-libs-2.3.3-2.el8.x86_64                                                            3/3

Upgraded:
  cryptsetup-libs-2.3.3-4.el8.x86_64

Installed:
  cryptsetup-2.3.3-4.el8.x86_64

Complete!
[root@node1 ~]#

How to configure encrypted storage with LUKS using passphrases

Initialize a LUKS partition with the command: cryptsetup luksFormat device

Potential containers for a “LUKS partition”: /dev/sda3/dev/sdb/dev/VG/LV/dev/mapper/mpath1, etc.
From here on in this document, this will be referred to as DEV

# cryptsetup luksFormat /dev/sdb
# cryptsetup luksFormat /dev/vgcrypt/lvcrypt
Opening the Encrypted Storage Device
Once your storage device /dev/vgcrypt/lvcrypt is encrypted, you can decrypt it and map it as data on your computer with one of the following commands:
# cryptsetup -v open /dev/vgcrypt/lvcrypt data
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Device data is created and it is of the type crypt.

Creating a Filesystem on the Decrypted Storage Device

Once you’ve decrypted the storage device /dev/vgcrypt/lvcrypt
and mapped it as the data storage device. Then, you can use the mapped storage device data as usual.
To create an XFS filesystem on the decrypted storage device data, run the following command:

Mounting the Decrypted Filesystem:

Once you’ve created a filesystem on your decrypted storage device data, you can mount it on your computer as usual.

# mount /dev/mapper/data /temp/

The decrypted storage device data is mounted on the /temp directory

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