CentOS Stream 9 – Common Problem 031 – Diagnosis and Fix

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

firewall rules disappear after reboot on CentOS Stream 9.

Environment & Reproduction

Hosts where rules were added with –runtime-only by mistake.

cat /etc/os-release
uname -r
rpm -qa | grep 

Root Cause Analysis

Missing –permanent flag or zone bound to wrong interface.

Quick Triage

Confirm package, network, SELinux and firewall state.

firewall-cmd --state
firewall-cmd --list-all
firewall-cmd --get-active-zones

Step-by-Step Diagnosis

Drill into network/firewalld state and recent journal entries to isolate the failure.

firewall-cmd --runtime-to-permanent --dry-run
journalctl -u firewalld -n 50

Solution – Primary Fix

Apply the standard remediation for network/firewalld on CentOS Stream 9.

sudo firewall-cmd --permanent --zone=public --add-service=https
sudo firewall-cmd --reload

Solution – Alternative Approaches

Use rich rules for source-restricted access.

Verification & Acceptance Criteria

Validate the fix with positive functional checks before closing.

firewall-cmd --list-all --permanent

Rollback Plan

Revert to the previous known-good configuration if the fix regresses.

sudo firewall-cmd --permanent --remove-service=https
sudo firewall-cmd --reload

Prevention & Hardening

Codify the fix in configuration management and add monitoring.

Manage with ansible.posix.firewalld and idempotent state.

Related Errors & Cross-Refs

nftables backend warnings and zone drift.

Related tutorial: View the step-by-step tutorial for centos-stream-9.

View all centos-stream-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

firewalld zone reference.