FreeBSD 13 – ipfw default deny policy drops outbound application traffic

📖 ~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

Apps can accept inbound traffic but fail on outbound dependencies.

Environment & Reproduction

Observed after strict ipfw policy rollout or rule reindexing.

Root Cause Analysis

Stateful egress allow rules are missing or shadowed by denies.

Quick Triage

Review ipfw counters and identify first-hit deny entries.

Step-by-Step Diagnosis

Correlate deny counters with destination hosts, ports, and traces.

Solution – Primary Fix

Add explicit keep-state egress rules for required upstream traffic.

Solution – Alternative Approaches

Use table-based allowlists for maintainable outbound policy.

Verification & Acceptance Criteria

Outbound calls succeed and deny counters stop rising for valid flows.

Rollback Plan

Remove added rules and restore prior stable ruleset snapshot.

Prevention & Hardening

Version-control firewall policy and test egress paths in CI.

Related Errors & Cross-Refs

Can resemble DNS or proxy outages when only select ports fail.

Related tutorial: View the step-by-step tutorial for FreeBSD 13.

View all FreeBSD 13 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

ipfw man pages and FreeBSD packet filtering best practices.