CentOS Stream 10 – Common Problem 104 – 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

Expected traffic is dropped after a firewalld reload or default-zone change.

Environment & Reproduction

Frequent on multi-NIC hosts and after firewall-cmd –runtime-to-permanent gaps.

Root Cause Analysis

Active zone or interface assignment differs from the intended policy.

Quick Triage

Run firewall-cmd –get-active-zones and –list-all per zone.

Step-by-Step Diagnosis

Compare runtime vs permanent with firewall-cmd –permanent –list-all.

Solution – Primary Fix

Reassign interface to the correct zone and add required services/ports.

Solution – Alternative Approaches

Use rich rules for fine-grained allow/deny pending policy redesign.

Verification & Acceptance Criteria

Traffic flows on intended ports and zones survive a daemon reload.

Rollback Plan

Revert with firewall-cmd –reload after restoring saved XML zone files.

Prevention & Hardening

Track zone assignments in Ansible or Cockpit network module.

Related Errors & Cross-Refs

Related to NetworkManager connection.zone mismatches.

Related tutorial: View the step-by-step tutorial for centos-stream-10.

View all centos-stream-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

firewalld upstream docs and zones(5) man page.