We’ll be using Ansible to change and maintain our firewall settings on a server.

The playbook will do the following.

1. Set the default zone to drop (Drops all external traffic to server)
2. Set a zone for internal access
3. Allow access from RFC1918 addresses to internal zone (Any local IP address will be able to access the server)
4. Enable the services and ports specified in the vars section
5. Disable the services listed in firewall_disable_services variable

Modify the variables as needed for your server(s). You can also add or move the variables to the inventory or host_vars files.

If you need to create an inventory file, refer to the first part of this post

BE CAREFUL CHANGING FIREWALL SETTINGS!!! IMPROPER SETTINGS COULD RENDER THE SERVER INACCESSIBLE!!!

Playbook for firewalld

Change the variables under the vars section

---
- name: Configure firewalld
  hosts: rhel
  gather_facts: yes
  become: yes

  vars: 
    firewall_allowed_ips:
      - 10.0.0.0/8
      - 172.16.0.0/12
      - 192.168.0.0/16
    firewall_allowed_services:
      - ssh
      - https
      - snmp
    firewall_allowed_ports:
      - "2222/tcp"
    firewall_disable_services:
      - cockpit
      - dhcpv6-client
      - mdns
      - samba-client

  tasks: 
  - name: Set default zone to drop
    ansible.builtin.command: firewall-cmd --set-default-zone=drop
    register: default_zone_set
    changed_when:
      - '"ZONE_ALREADY_SET" not in default_zone_set.stderr'

  - name: Enable and allow access to internal zone from RFC1918 addresses
    ansible.posix.firewalld:
      source: "{{ item }}"
      zone: internal
      permanent: true
      immediate: true
      state: enabled
    with_items: "{{ firewall_allowed_ips }}"

  - name: Disable unused services for internal zone
    ansible.posix.firewalld:
      service: "{{ item }}"
      zone: internal
      permanent: true
      immediate: true
      state: disabled
    with_items: "{{ firewall_disable_services }}"


  - name: Set services for internal zone
    ansible.posix.firewalld:
      service: "{{ item }}"
      zone: internal
      permanent: true
      immediate: true
      state: enabled
    with_items: "{{ firewall_allowed_services }}"

  - name: Set custom ports for internal zone
    ansible.posix.firewalld:
      port: "{{ item }}"
      zone: internal
      permanent: true
      immediate: true
      state: enabled
    with_items: "{{ firewall_allowed_ports }}"

Helpful links

https://docs.ansible.com/ansible/latest/collections/ansible/posix/firewalld_module.html#parameter-source

https://stackoverflow.com/questions/51563643/how-to-change-firewalld-zone-using-ansible

https://www.middlewareinventory.com/blog/ansible-firewalld/