Learn how to configure firewalld on CentOS to manage zones, open ports, allow services, and secure your server.

DigitalOcean Community's platform is a central hub for developers and sysadmins using DigitalOcean's cloud infrastructure, offering insights into cloud computing, DevOps practices, and open-source technologies. Through tutorials, Q&A, and community forums, DO_Community offers insights into deploying and managing applications on DigitalOcean's cloud platform. Developers can learn about Linux server administration, containerization, and automation tools to build and scale applications in the cloud.

DigitalOcean Community

A comprehensive guide to setting up and managing a firewall on CentOS using firewalld. Covers installation, enabling the service, understanding zones (public, home, work, dmz, trusted), and the difference between runtime and permanent rules. Explains how to allow services (SSH, HTTP, HTTPS) and open custom ports, create custom service definitions and zones, and troubleshoot common issues like SSH lockouts, rules not persisting after reboot, and wrong zone assignments. Also clarifies the relationship between firewalld, iptables, and nftables on modern CentOS Stream 10 systems.

How To Set Up a Firewall Using firewalld on CentOS

Install and Enable Your Firewall to Start at Boot

Getting Familiar with the Current Firewall Rules