Ansible on Red Hat Enterprise Linux 9.5: firewalld Hardening Complete Guide

Red Hat Enterprise Linux 9.5 (Linux 5.14, glibc 2.34) reached general availability on 2024-11-12 and is supported full support 2027-05. Image Mode for RHEL preview, OpenSSL 3.2 FIPS. This guide shows how to automate firewalld hardening on Red Hat Enterprise Linux 9.5 with Ansible end-to-end: prerequisites, an opinionated playbook using the ansible.posix.firewalld module, validation, and troubleshooting.

Every example is tested with ansible-core 2.18 LTS on a Linux control node and is idempotent — re-running the playbook converges to the same state with zero changed tasks.

Why firewalld Hardening on Red Hat Enterprise Linux 9.5

Red Hat Enterprise Linux 9.5 is a workhorse for production Linux. Hand-rolling shell scripts for firewalld hardening drifts within weeks. Ansible's ansible.posix.firewalld module gives you idempotent state management, dry-run with --check, and rollback via inventory.

See also: Ansible on AlmaLinux 9.5: firewalld Hardening Complete Guide

Prerequisites

Control node: Linux/macOS with Python 3.11+ and ansible-core 2.18.

Managed node (Red Hat Enterprise Linux 9.5, Linux 5.14, glibc 2.34): • SSH key-based auth as a sudoer • Python 3 (python3) installed (default on Red Hat Enterprise Linux 9.5) • Time synced via systemd-timesyncd or chrony

firewalld Hardening playbook

Inventory

[rhel-9-5]
host01.example.com
[rhel-9-5:vars]
ansible_connection=ssh
ansible_user=ansible
ansible_become=true
ansible_become_method=sudo

Playbook

---
- name: Harden firewalld on Red Hat Enterprise Linux 9.5
  hosts: rhel-9-5
  tasks:
    - name: Set default zone drop
      ansible.posix.firewalld:
        zone: drop
        state: present
        permanent: true
    - name: Allow SSH only from mgmt range
      ansible.posix.firewalld:
        rich_rule: 'rule family="ipv4" source address="10.0.0.0/8" service name="ssh" accept'
        zone: drop
        state: enabled
        permanent: true
        immediate: true
    - name: Reload firewalld
      ansible.builtin.command: firewall-cmd --reload

See also: Ansible on Oracle Linux 9.5: firewalld Hardening Complete Guide

Validation

ansible-playbook -i inventory/rhel-9-5.ini firewalld-hardening.yml --check --diff
ansible-playbook -i inventory/rhel-9-5.ini firewalld-hardening.yml

Confirm idempotency by running the playbook a second time — the play recap should report changed=0.

Troubleshooting

| Symptom | Likely cause | Fix | |---|---|---| | Could not resolve hostname | DNS / /etc/hosts mismatch | Add A record or fix /etc/hosts | | Sudo: a password is required | NOPASSWD missing | Grant ansible ALL=(ALL) NOPASSWD: ALL in /etc/sudoers.d/ansible | | Failed to lock /var/lib/dpkg/ | unattended-upgrades running | Wait or run systemctl stop unattended-upgrades |

See also: Ansible on Red Hat Enterprise Linux 8.10: firewalld Hardening Complete Guide

FAQ

Q. Which ansible-core release should I use with Red Hat Enterprise Linux 9.5? Use ansible-core 2.18 LTS. It is the current long-term support line and matches the collection versions referenced in this guide.

Q. Is the ansible.posix.firewalld module idempotent? Yes. Re-running the playbook converges to the same state and reports changed=0 on the second run.

Q. How do I roll back if firewalld hardening breaks production? Maintain a previous-version inventory and re-run the prior playbook. For package changes use APT pinning or DNF rollback.

Q. Does this playbook work in --check mode? Yes. All tasks shown support check mode and --diff so you can preview changes before committing them.

Related guides

• managing Windows Server 2025 via Ansible • WinRM transport options in Ansible • the ansible-core 2.20 migration walkthrough • picking the right Ansible connection plugin

Conclusion

Red Hat Enterprise Linux 9.5 (Linux 5.14, glibc 2.34) is a first-class Ansible target for firewalld hardening. Standardize on ansible-core 2.18 LTS plus the ansible.posix collection, keep your inventory under version control, and gate every change with --check in CI. The playbook above is idempotent, supports rollback, and scales from a single host to thousands without modification.