main.yml

---
- hosts: all
  become: true

  handlers:
    - name: restart ssh
      service: name=sshd state=restarted

  tasks:
    # Use secure and encrypted communication.
    - name: Allow sshd to listen on tcp port 2849.
      seport:
        ports: 2849
        proto: tcp
        setype: ssh_port_t
        state: present
      when: ansible_selinux.status == 'enabled'

    - name: Update SSH configuration to be more secure.
      lineinfile:
        dest: /etc/ssh/sshd_config
        regexp: "{{ item.regexp }}"
        line: "{{ item.line }}"
        state: present
        validate: 'sshd -t -f %s'
      with_items:
        - regexp: "^PasswordAuthentication"
          line: "PasswordAuthentication no"
        - regexp: "^PermitRootLogin"
          line: "PermitRootLogin no"
        - regexp: "^Port"
          line: "Port 2849"
      notify: restart ssh

    # User account configuration.
    - name: Add a deployment user.
      user:
        name: johndoe
        state: present

    # Disable root login and use `sudo`.
    - name: Add sudo rights for deployment user.
      lineinfile:
        dest: /etc/sudoers
        regexp: '^johndoe'
        line: 'johndoe ALL=(ALL) NOPASSWD: ALL'
        state: present
        validate: 'visudo -cf %s'

    # Remove unused software, open only required ports.
    - name: Remove unused packages.
      package:
        name:
          - nano
          - sendmail
        state: absent

    # File permissions.
    - name: Configure the permissions for the messages log.
      file:
        path: /var/log/messages
        owner: root
        group: root
        mode: 0600

    # Automating updates for RHEL systems.
    - name: Install dnf-automatic.
      yum:
        name: dnf-automatic
        state: present

    - name: Ensure dnf-automatic is running and enabled on boot.
      service:
        name: dnf-automatic-install.timer
        state: started
        enabled: yes

    # Automating updates for Debian systems.
    - name: Install unattended upgrades package.
      apt:
        name: unattended-upgrades
        state: present
      when: ansible_os_family == 'Debian'

    - name: Copy unattended-upgrades configuration files in place.
      template:
        src: "../templates/{{ item }}.j2"
        dest: "/etc/apt/apt.conf.d/{{ item }}"
        owner: root
        group: root
        mode: 0644
      with_items:
        - 20auto-upgrades
        - 50unattended-upgrades
      when: ansible_os_family == 'Debian'

    # Configuring a firewall with `firewalld` on RHEL.
    - name: Ensure firewalld is running.
      service:
        name: firewalld
        state: started

    - name: Configure open ports with firewalld.
      firewalld:
        state: "{{ item.state }}"
        port: "{{ item.port }}"
        zone: external
        immediate: yes
        permanent: yes
      with_items:
        - { state: 'enabled', port: '22/tcp' }
        - { state: 'enabled', port: '80/tcp' }
        - { state: 'enabled', port: '123/udp' }

    # Monitor logins and block suspect IP addresses.
    - name: Ensure EPEL repo is present.
      yum:
        name: epel-release
        state: present
      when: ansible_os_family == 'RedHat'

    - name: Install fail2ban (RedHat).
      yum:
        name: fail2ban
        state: present
        enablerepo: epel
      when: ansible_os_family == 'RedHat'

    - name: Install fail2ban (Debian).
      apt:
        name: fail2ban
        state: present
      when: ansible_os_family == 'Debian'

    - name: Ensure fail2ban is running and enabled on boot.
      service:
        name: fail2ban
        state: started
        enabled: yes

    # Use SELinux (Security-Enhanced Linux).
    - name: Install Python SELinux library.
      yum:
        name: python3-libselinux
        state: present

    - name: Ensure SELinux is enabled in `targeted` mode.
      selinux:
        policy: targeted
        state: enforcing

    - name: Ensure httpd can connect to the network.
      seboolean:
        name: httpd_can_network_connect
        state: yes
        persistent: yes
      when: ansible_selinux.status == 'enabled'