📖 ~1 min read
Table of contents
Symptom & Impact
Firewall policy disappears after reboot, exposing services or blocking required traffic.
Environment & Reproduction
Occurs when runtime rules are loaded but not persisted in system config.
Root Cause Analysis
Firewall service starts with empty or outdated ruleset, replacing runtime state.
Quick Triage
Compare live ruleset and service startup status immediately after boot.
Step-by-Step Diagnosis
Review rules file syntax, startup ordering, and journal messages for load failures.
Solution – Primary Fix
Save validated rules, enable persistent service startup, and test reboot persistence.
Still having issues? Our IT Consulting team can diagnose and resolve this for you. Get in touch for a free consultation.
Solution – Alternative Approaches
Deploy firewall policy from configuration management for deterministic host baselines.
Verification & Acceptance Criteria
Post-reboot ruleset matches baseline and expected ports enforce intended policy.
Rollback Plan
Restore previous firewall file and restart service if new rules break traffic.
Prevention & Hardening
Validate firewall syntax in CI and run compliance checks after reboot.
Related Errors & Cross-Refs
Service failed, syntax error near token, and missing chain/table definitions.
Related tutorial: View the step-by-step tutorial for Debian 9.
View all Debian 9 tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
Debian nftables guidance and upstream command syntax documentation.
Need Expert Help?
If you cannot resolve this yourself, our team offers hands-on Server Management, Managed IT Services, and flexible Support Plans. Contact us today — we respond within one business day.
