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Chapter 9. Configuring firewalld using System Roles

You can use the firewall System Role to configure settings of the firewalld service on multiple clients at once. This solution:

  • Provides an interface with efficient input settings.
  • Keeps all intended firewalld parameters in one place.

After you run the firewall role on the control node, the System Role applies the firewalld parameters to the managed node immediately and makes them persistent across reboots.

9.1. Introduction to the firewall RHEL System Role

RHEL System Roles is a set of contents for the Ansible automation utility. This content together with the Ansible automation utility provides a consistent configuration interface to remotely manage multiple systems.

The rhel-system-roles.firewall role from the RHEL System Roles was introduced for automated configurations of the firewalld service. The rhel-system-roles package contains this System Role, and also the reference documentation.

To apply the firewalld parameters on one or more systems in an automated fashion, use the firewall System Role variable in a playbook. A playbook is a list of one or more plays that is written in the text-based YAML format.

You can use an inventory file to define a set of systems that you want Ansible to configure.

With the firewall role you can configure many different firewalld parameters, for example:

  • Zones.
  • The services for which packets should be allowed.
  • Granting, rejection, or dropping of traffic access to ports.
  • Forwarding of ports or port ranges for a zone.

Additional resources

9.2. Resetting the firewalld settings using the firewall RHEL System Role

With the firewall RHEL system role, you can reset the firewalld settings to their default state. If you add the previous:replaced parameter to the variable list, the System Role removes all existing user-defined settings and resets firewalld to the defaults. If you combine the previous:replaced parameter with other settings, the firewall role removes all existing settings before applying new ones.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on the them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.

Procedure

  1. Create a playbook file, for example ~/reset-firewalld.yml, with the following content: 

    ---
- name: Reset firewalld example
  hosts: managed-node-01.example.com
  tasks:
  - name: Reset firewalld
    include_role:
      name: rhel-system-roles.firewall

    vars:
      firewall:
        - previous: replaced

  2. Run the playbook: 

    # ansible-playbook ~/configuring-a-dmz.yml

Verification

  • Run this command as root on the managed node to check all the zones: 

    # firewall-cmd --list-all-zones

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.firewall/README.md
  • ansible-playbook(1)
  • firewalld(1)

9.3. Forwarding incoming traffic from one local port to a different local port

With the firewall role you can remotely configure firewalld parameters with persisting effect on multiple managed hosts.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on the them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.

Procedure

  1. Create a playbook file, for example ~/port_forwarding.yml, with the following content: 

    ---
- name: Configure firewalld
  hosts: managed-node-01.example.com
  tasks:
  - name: Forward incoming traffic on port 8080 to 443
    include_role:
      name: rhel-system-roles.firewall

    vars:
      firewall:
        - { forward_port: 8080/tcp;443;, state: enabled, runtime: true, permanent: true }

  2. Run the playbook: 

    # ansible-playbook ~/port_forwarding.yml

Verification

  • On the managed host, display the firewalld settings: 

    # firewall-cmd --list-forward-ports

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.firewall/README.md

9.4. Configuring ports using System Roles

You can use the RHEL firewall System Role to open or close ports in the local firewall for incoming traffic and make the new configuration persist across reboots. For example you can configure the default zone to permit incoming traffic for the HTTPS service.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on the them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.

Procedure

  1. Create a playbook file, for example ~/opening-a-port.yml, with the following content: 

    ---
- name: Configure firewalld
  hosts: managed-node-01.example.com
  tasks:
  - name: Allow incoming HTTPS traffic to the local host
    include_role:
      name: rhel-system-roles.firewall

    vars:
      firewall:
        - port: 443/tcp
          service: http
          state: enabled
          runtime: true
          permanent: true

    The permanent: true option makes the new settings persistent across reboots.

  2. Run the playbook: 

    # ansible-playbook ~/opening-a-port.yml

Verification

  • On the managed node, verify that the 443/tcp port associated with the HTTPS service is open: 

    # firewall-cmd --list-ports
443/tcp

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.firewall/README.md

9.5. Configuring a DMZ firewalld zone by using the firewalld RHEL System Role

As a system administrator, you can use the firewall System Role to configure a dmz zone on the enp1s0 interface to permit HTTPS traffic to the zone. In this way, you enable external users to access your web servers.

Perform this procedure on the Ansible control node.

Prerequisites

  • You have prepared the control node and the managed nodes
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on the them.
  • The managed nodes or groups of managed nodes on which you want to run this playbook are listed in the Ansible inventory file.

Procedure

  1. Create a playbook file, for example ~/configuring-a-dmz.yml, with the following content: 

    ---
- name: Configure firewalld
  hosts: managed-node-01.example.com
  tasks:
  - name: Creating a DMZ with access to HTTPS port and masquerading for hosts in DMZ
    include_role:
      name: rhel-system-roles.firewall

    vars:
      firewall:
        - zone: dmz
          interface: enp1s0
          service: https
          state: enabled
          runtime: true
          permanent: true

  2. Run the playbook: 

    # ansible-playbook ~/configuring-a-dmz.yml

Verification

  • On the managed node, view detailed information about the dmz zone: 

    # firewall-cmd --zone=dmz --list-all
dmz (active)
  target: default
  icmp-block-inversion: no
  interfaces: enp1s0
  sources:
  services: https ssh
  ports:
  protocols:
  forward: no
  masquerade: no
  forward-ports:
  source-ports:
  icmp-blocks:

Additional resources

  • /usr/share/ansible/roles/rhel-system-roles.firewall/README.md
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