AlmaLinux

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Table of Contents

1. About The Project
   • Built With
2. Getting Started
   • Prerequisites
3. Installation
4. Hardening
   • Creating Private/Public SSH Key
   • Adding SSH Public Key
   • SSH Permissions
   • Disabling password based SSH
   • Allow user to SUDO without password
   • fapolicyd
   • wget issues
5. License
6. Contact
7. Acknowledgments

About The Project

AlmaLinux Desktop GUI

• Installation of AlmaLinux
• Utilizing DISA STIG Profiles
• Creating ssh keys
• Disabling password based ssh logins
• Allow user to sudo without password
• Working with fapolicyd
• Getting wget to work in FIPS Mode
• Optional Cloud Packages
  • Cloud-Init
  • Cloud-Utils-Growpart
  • GDisk

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Built With

• Almalinux

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Getting Started

Prerequisites

1. Downloading AlmaLinux

   https://almalinux.org

2. Make bootable USB

• Linux:

  Insert your target USB and locate it. There are different ways to do it but here are some of them:

  • sudo fdisk -l - this command shows you the connected block storage devices, including the USB devices.

  • lsblk - this command gives you all the available block storage devices, including the USB block storage devices.

  • sudo blkid - this command gives you the same information as lsblk, but you have to rub it as root.

    You need to look for /dev/sda or /dev/sdb or /dev/sdc, which is your target USB.

    After you found out the location of your target USB, navigate to the location of your source ISO. Run dd command to copy files from ISO to USB:

    sudo dd if=/AlmaLinux-9-latest-x86_64-dvd.iso of=/dev/sdc status=progress

    dd : Start the dd command to write DVD/CD iso image. if=AlmaLinux-8-x86_64-Live-GNOME-Mini-beta-1.iso : path to the input file. of=/dev/sdc : path to destination USB disk/stick. status=progress: display a progress bar while writing the image to the USB stick such as /dev/sdb. That’s all! You now have ready Live AlmaLinux on a USB stick.

• Windows:

  For Windows OS there is a helpful free and open-source application - Rufus.

  Open the application, choose your target USB, ISO you need to burn, press start - and Live OS is ready to run.

• MacOS:

  The cross-platform tool balenaEtcher is used to write images on macOS. It is simple too. Open banlenaEtcher, choose the image and the USB, press Flash.

  More details and information about AlmaLinux Live Media can be found on Live Media SIG.

Installation

1. When starting up AlmaLinux for the first time you will be granted with a welcome screen. Here select your language and keyboard type. Click Continue
2. Begin Installation:
3. Select User Creation: Create a user and assign that user a strong password. Make sure both Make this user administrator and Require a password to use this account are checked. Click Done
4. Software Selection: For this instance we will select Minimal Install. Click Done
5. Security Profile: We will highlight DISA STIG and click on Select profile It will issue some errors, you can disregard them as we will correct it in the next section. Click Done
6. Installation Destination: For Storage Configuation select Custom. Click Done This will bring you to the manual partitioning page.
7. Manual Partitioning: Add all the following DATA and SYSTEM mount points.
8. Click on Modify under Volume Group and select "As large as possible" for Size policy. Click Save then click Done
9. Accept Partitioning Changes: Click on Accept Changes
10. Begin Installation: Click on Begin Installation to start installing AlmaLinux.

Congratulations you have installed AlmaLinux

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Hardening

Creating a SSH Key

Windows:

1. Open the Settings panel, then click Apps.

2. Under the Apps and Features heading, click Optional Features.
   

3. Scroll down the list to see if OpenSSH Client is listed.
   

   • If it’s not, click the plus-sign next to Add a feature.
     
   • Scroll through the list to find and select OpenSSH Client.
     
   • Finally, click Install.

4. Open Command Prompt.

   • Press the Windows key.
   • Type cmd.
   • Under Best Match, right-click Command Prompt.
   • Click Run as administrator

   

5. If prompted, click Yes in the Do you want to allow this app to make changes to your device? pop-up.

6. Use OpenSSH to Generate an SSH Key Pair

   • In the command prompt, type the following:

     ssh-keygen

     
   • By default, the system will save the keys to C:\Users\your_username/.ssh/id_rsa. You can use the default name, or you can choose more descriptive names. This can help distinguish between keys, if you are using multiple key pairs. To stick to the default option, press Enter.
   • You’ll be asked to enter a passphrase. Hit Enter to skip this step.
   • The system will generate the key pair, and display the key fingerprint and a randomart image.
   • Open your file browser.
   • Navigate to C:\Users\your_username/.ssh.
   • You should see two files. The identification is saved in the id_rsa file and the public key is labeled id_rsa.pub. This is your SSH key pair.

Linux:

In your preferred terminal run the command ssh-keygen

• By default, the system will save the keys to ~/.ssh.
• You should see two files. The identification is saved in the id_rsa file and the public key is labeled id_rsa.pub. This is your SSH key pair.

MacOS:

In Terminal run the command ssh-keygen

• By default, the system will save the keys to /Users/myname/.ssh.
• You should see two files. The identification is saved in the id_rsa file and the public key is labeled id_rsa.pub. This is your SSH key pair.

SSH Permissions

mkdir -p ~/.ssh
touch ~/.ssh/authorized_keys
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

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Adding SSH Public Key

Replace $SSH with the content of the public key.

echo "$SSH" >> ~/.ssh/authorized_keys

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Disabling password based SSH

cd /etc/ssh
sed -i 's/#PasswordAuthentication yes/PasswordAuthentication no/g' sshd_config
systemctl restart sshd

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Allow user to SUDO without password

sudo su -
visudo

Press Insert on keyboard, substitute $USER with the user you created during installation.

$USER  ALL=(ALL) NOPASSWD: ALL

Press esc then type

:wq

This will save and close the terminal.

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Working with fapolicyd

fapolicyd starts in protection mode. We need to set fapolicyd to permissive mode to allow us to build the necessary rule sets for our individual systems.

cd /etc/fapolicyd/
sed -i 's/permissive = 0/permissive = 1/g' fapolicyd.conf
systemctl restart fapolicyd

See RHEL: Blocking and Allowing applications with fapolicyd for more information on building rules.

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Fixing wget

As of current GnuTLS is not properly working with FIPS. To correct this we tell GnuTLS to disable health checks.

export GNUTLS_SKIP_FIPS_INTEGRITY_CHECKS=1

# Lets make is persistant
cd /etc/profile.d/
touch gnutls.sh
echo "export GNUTLS_SKIP_FIPS_INTEGRITY_CHECKS=1" > gnutls.sh

wget will now function as intended.

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Optional Cloud Configurations:

cloud-init: Cloud images are operating system templates and every instance starts out as an identical clone of every other instance. It is the user data that gives every cloud instance its personality and cloud-init is the tool that applies user data to your instances automatically.

dnf install -y cloud-init

cloud-utils-growpart: Provides the growpart script for growing a partition. It is primarily used in cloud images in conjunction with the dracut-modules-growroot package to grow the root partition on first boot.

dnf install -y cloud-utils-growpart

gdisk: GDISK command is used to partition the drives of your system. Works with cloud-init for partition resizing.

dnf install -y gdisk

License:

Distributed under the MIT License. See LICENSE for more information.

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Contact:

Twitter - @skynetinctech

Linkedin - Charles Showalter

Instagram - @skynetinc.tech

Facebook - @skynetinctech

Project Link: https://lab.skynetinc.tech/WorldDrknss/Guide-to-AlmaLinux/

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