Ansible on Juniper Junos 23.4: Interface Hardening Complete Guide

Juniper Junos 23.4 (Junos 23.4R2) reached general availability on 2024 and is supported EOL 2027. MX/QFX/SRX; junipernetworks.junos collection. This guide shows how to automate interface hardening on Juniper Junos 23.4 with Ansible end-to-end: prerequisites, an opinionated playbook using the junipernetworks.junos 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 Interface Hardening on Juniper Junos 23.4

Network devices running Juniper Junos 23.4 expose a CLI that drifts the moment a human types into it. Ansible's junipernetworks.junos collection talks NETCONF/SSH and gives you idempotent intent-based config you can review in pull requests.

See also: Ansible on Juniper Junos 23.4: Configuration Backup and Diff Complete Guide

Prerequisites

Control node: • Python 3.11+ and ansible-core 2.18 • The junipernetworks.junos collection installed: ansible-galaxy collection install junipernetworks.junos • paramiko for network_cli connection or ncclient for NETCONF

Managed device (Juniper Junos 23.4, Junos 23.4R2): • SSH enabled with a privilege-15 (or equivalent) user • (Optional) NETCONF over SSH for structured config • MX/QFX/SRX; junipernetworks.junos collection.

Interface Hardening playbook

Inventory

[juniper-junos-23-4]
device01.lab.example.com
[juniper-junos-23-4:vars]
ansible_connection=network_cli
ansible_network_os=junipernetworks_junos
ansible_user=netadmin
ansible_password='{{ vault_network_password }}'
ansible_become=true
ansible_become_method=enable

Playbook

---
- name: Interface hardening on Juniper Junos 23.4
  hosts: juniper-junos-23-4
  gather_facts: false
  tasks:
    - name: Disable unused interfaces
      junipernetworks.junos.junos_interfaces:
        config:
          - { name: Ethernet24, enabled: false, description: 'unused — disabled by ansible' }
          - { name: Ethernet23, enabled: false, description: 'unused — disabled by ansible' }
        state: merged
    - name: Disable dynamic trunking on access ports
      junipernetworks.junos.junos_l2_interfaces:
        config:
          - { name: Ethernet1, mode: access, access: { vlan: 10 } }
        state: merged

See also: Ansible on Juniper Junos 23.4: OSPF Routing Configuration Complete Guide

Validation

ansible-playbook -i inventory/juniper-junos-23-4.ini interface-hardening.yml --check --diff
ansible-playbook -i inventory/juniper-junos-23-4.ini interface-hardening.yml

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

Troubleshooting

| Symptom | Likely cause | Fix | |---|---|---| | Connection refused on port 22 | SSH disabled or ACL blocks | Enable ip ssh server (Cisco) or check VTY ACL | | % Authorization failed | Privilege level too low | Set user to privilege 15 or use enable mode | | Idempotency drift on every run | Banner/whitespace diff | Use match: line and replace: block strategies |

See also: Ansible on Juniper Junos 23.4: VLAN and Trunk Configuration Complete Guide

FAQ

Q. Which ansible-core release should I use with Juniper Junos 23.4? 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 junipernetworks.junos 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 interface 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

• PSRP and OpenSSH on Windows Server 2025 via Ansible • Kerberos and NTLM authentication for Ansible WinRM • the ansible-core 2.20 migration walkthrough • configuring Ansible connection variables

Conclusion

Juniper Junos 23.4 (Junos 23.4R2) is a first-class Ansible target for interface hardening. Standardize on ansible-core 2.18 LTS plus the junipernetworks.junos 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.