Can’t Connect to Your Application? Check the Firewall.
AlmaLinux has become the go-to Enterprise Linux distribution for VPS hosting, replacing CentOS. It comes with a robust firewall management tool called firewalld enabled by default.
While this is great for security, it often causes confusion for new server owners. You might install a web server (Nginx/Apache) or a game server, only to find that you can’t connect. The reason? You need to explicitly allow traffic through specific ports.
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Step 1: Check Firewall Status
Before making changes, verify that the firewall is running. Log in via SSH and run:
systemctl status firewalldIf it says active (running), you are ready to proceed.
Step 2: Allow a Specific Port (Temporary)
To open a port (for example, port 80 for HTTP traffic) immediately, use the firewall-cmd tool:
sudo firewall-cmd --zone=public --add-port=80/tcpNote: This change will be lost if you reboot the server. It is good for testing.
Step 3: Make the Rule Permanent
Once you confirmed that everything works, you must make the rule permanent so it survives server reboots. Add the --permanent flag:
sudo firewall-cmd --zone=public --permanent --add-port=80/tcpYou can also open a range of ports (useful for passive FTP or game servers):
sudo firewall-cmd --zone=public --permanent --add-port=3000-4000/tcpStep 4: Reload the Firewall (Crucial!)
For the permanent changes to take effect, you must reload the configuration:
sudo firewall-cmd --reloadStep 5: Verify Open Ports
To see a list of all currently open ports and services, run:
sudo firewall-cmd --list-allConclusion
Understanding firewalld is essential for any Linux administrator. It ensures your WPressly VPS remains secure while allowing necessary traffic for your applications.
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