Regex in Action: Tuning Fail2ban with Ansible

Regex has been a constant in nearly every coding project I’ve worked on. And since infrastructure today is also built on code, regex patterns are everywhere—for instance, in the configurations of DevOps tools operating within the context of Infrastructure as Code (IaC). For a demonstration, I’ve pulled a snippet from an Ansible playbook that adjusts the maxretry in Fail2ban to two attempts before blocking SSH access. ... - name: Set the maxretry in fail2ban to 2. lineinfile: path: /etc/fail2ban/jail.d/ssh.conf regexp: '^maxretry =' line: 'maxretry = 2' create: yes notify: Restart fail2ban ... The regex in the lineinfile module tweaks only the maxretry parameter in the ssh.conf configuration file for Fail2ban. If needed, the same approach can apply to adjustments like worker_connections in Nginx or file open limits in limits.conf for Docker, ensuring precise environment configurations.

Apr 2, 2025 - 23:26

Regex in Action: Tuning Fail2ban with Ansible

Regex has been a constant in nearly every coding project I’ve worked on. And since infrastructure today is also built on code, regex patterns are everywhere—for instance, in the configurations of DevOps tools operating within the context of Infrastructure as Code (IaC).

For a demonstration, I’ve pulled a snippet from an Ansible playbook that adjusts the maxretry in Fail2ban to two attempts before blocking SSH access.

...

    - name: Set the maxretry in fail2ban to 2.
      lineinfile:
        path: /etc/fail2ban/jail.d/ssh.conf
        regexp: '^maxretry ='
        line: 'maxretry = 2'
        create: yes
      notify: Restart fail2ban

...

The regex in the lineinfile module tweaks only the maxretry parameter in the ssh.conf configuration file for Fail2ban. If needed, the same approach can apply to adjustments like worker_connections in Nginx or file open limits in limits.conf for Docker, ensuring precise environment configurations.