Basic Server Configuration

The following configuration is based on Almalinux 9.5.

🐧 Linux Command Line

Core

Enable Repositories and Install Packages

dnf config-manager --set-enabled crb
dnf install -y epel-release
dnf install -y lrzsz screen dnf-automatic htop vim
systemctl enable --now dnf-automatic.timer
hostnamectl set-hostname <host-name>

Start a Screen Session

# Reattach to a screen session or create a new one
screen -R <session-name>

# Detach from the current screen session
# ctrl+a d

# List all sessions
# screen -ls

Configure Vim Editor

~/.vimrc

syntax on
set hlsearch
set showmatch
set tabstop=4
set shiftwidth=4
set expandtab

Add Bash History and Aliases

cat >> ~/.bashrc << EOF
HISTSIZE=1000
HISTFILESIZE=2000
alias ll='ls -alh'
EOF
source ~/.bashrc

Configure Automatic Updates

/etc/dnf/automatic.conf

upgrade_type = security
apply_updates = yes

Set Login Warning Message

tee /etc/issue /etc/issue.net /etc/motd << EOF
*** Warning ***
Authorized access only! This is a private system.
All connections are monitored and recorded.
Unauthorized access or use may lead to prosecution.
Disconnect IMMEDIATELY if you are not an authorized user!
EOF

Update System Packages

dnf upgrade -y
# dnf upgrade -y = dnf update -y = yum update -y

Reboot System

reboot

Optional

Enable Fastest Mirror Plugin

/etc/dnf/dnf.conf

fastestmirror=True

Create Swap Space if Needed

yum install util-linux
## Create a 2GB swap file
fallocate -l 2G /swapfile
chmod 600 /swapfile
mkswap /swapfile
swapon /swapfile

# vi /etc/sysctl.conf, allow the system to use swap space when memory is low.
vm.swappiness=1

# vi /etc/fstab, add the following line to the end of the file
/swapfile    swap    swap    default    0    0

# uninstall: swapoff -v /swapfile

Ansible Playbook

Install Ansible and start a screen session

dnf config-manager --set-enabled crb
dnf install -y epel-release
dnf install -y ansible-core screen
screen -R setup

vi /etc/ansible/hosts

[local]
localhost ansible_connection=local

Run Playbook

ansible-playbook basic-server-configuration.yml

# Dry-run
# ansible-playbook --check basic-server-configuration.yml

basic-server-configuration.yml

- name: Basic Server Configuration
  hosts: all
  remote_user: root
  vars:
    swap_size: "2G"
  vars_prompt:
    - name: host_name
      prompt: "Enter the hostname for this server"
      private: false
    - name: enable_fastest_mirror
      prompt: "Enable the Fastest Mirror Plugin? (Y/n)"
      private: false
      default: "Y"
    - name: add_swapfile
      prompt: "Do you want to configure a swapfile? (Y/n)"
      private: false
      default: "Y"

  tasks:
    - name: Set hostname
      command: hostnamectl set-hostname {{ host_name }}
      register: hostname_result
      changed_when: hostname_result.rc != 0

    - name: Install packages
      dnf:
        name:
          - lrzsz
          - dnf-automatic
          - htop
          - vim
        state: present

    - name: Enable Fastest Mirror Plugin
      ini_file:
        path: /etc/dnf/dnf.conf
        section: main
        option: fastestmirror
        value: "True"
        mode: "0644"
      when: enable_fastest_mirror | lower == 'y'

    - name: Configure .vimrc
      copy:
        dest: ~/.vimrc
        content: |
          syntax on
          set hlsearch
          set showmatch
          set tabstop=4
          set shiftwidth=4
          set expandtab
        mode: "0644"

    - name: Add alias ll to .bashrc
      lineinfile:
        path: ~/.bashrc
        line: "alias ll='ls -alh'"
      notify:
        - reload bashrc
      when: "'alias ll' not in lookup('file', '~/.bashrc')"

    - name: Configure system messages
      copy:
        dest: "{{ item }}"
        content: |
          ***Warning***
          Authorised access only! This is a private system.
          All connections are monitored and recorded.
          Unauthorized access or use may lead to prosecution.
          Disconnect IMMEDIATELY if you are not an authorized user!
        mode: "0644"
      with_items:
        - /etc/issue
        - /etc/issue.net
        - /etc/motd
      timeout: 10

    - name: Configure dnf-automatic for security updates
      lineinfile:
        path: /etc/dnf/automatic.conf
        regexp: "^upgrade_type ="
        line: "upgrade_type = security"
        state: present
      notify:
        - enable dnf-automatic

    - name: Enable and start dnf-automatic timer
      systemd:
        name: dnf-automatic.timer
        enabled: true
        state: started

    - name: Update system packages (/tmp/dnf_update_output.log)
      shell: |
        set -o pipefail
        dnf upgrade -y | tee /tmp/dnf_update_output.log
      register: update_output
      changed_when: update_output.rc != 0

    - name: Display reboot message
      debug:
        msg: "The system has been updated. Please consider rebooting your computer."

    - name: Install util-linux (required for swapfile creation)
      dnf:
        name: util-linux
        state: present
      when: add_swapfile | lower == 'y'

    - block:
        - name: Create a swapfile
          command: fallocate -l {{ swap_size }} /swapfile
          args:
            creates: /swapfile

        - name: Secure the swapfile
          file:
            path: /swapfile
            owner: root
            group: root
            mode: "0600"

        - name: Format the swapfile
          command: mkswap /swapfile
          args:
            creates: /swapfile

        - name: Enable swapfile
          command: swapon /swapfile
          register: swapfile_enable
          changed_when: swapfile_enable.rc == 0
      rescue:
        - name: Report swapfile creation failure
          debug:
            msg: "Failed to create or enable swapfile"
      when: add_swapfile | lower == 'y'

    - name: Update sysctl.conf for swappiness
      lineinfile:
        path: /etc/sysctl.conf
        regexp: "^vm.swappiness="
        line: "vm.swappiness=1"
        state: present
      when: add_swapfile | lower == 'y'
      notify: reload system daemon

    - name: Update fstab for swapfile
      lineinfile:
        path: /etc/fstab
        line: "/swapfile    swap    swap    defaults    0    0"
        state: present
      when: add_swapfile | lower == 'y'
      notify: reload system daemon

  handlers:
    - name: reload bashrc
      command: bash -c "source ~/.bashrc"

    - name: enable dnf-automatic
      systemd:
        name: dnf-automatic.timer
        enabled: true
        state: started

    - name: reload system daemon
      systemd:
        daemon_reload: true