FreeBSD 14 – 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

Services can accept connections but fail to reach upstream APIs due to outbound packet drops.

Environment & Reproduction

Observed after strict ipfw ruleset rollout or reordered numbered rules.

service ipfw status
ipfw list
fetch -o /dev/null https://example.com || true

Root Cause Analysis

A deny rule with broad match criteria or missing stateful pass rule intercepts egress traffic.

Quick Triage

Check counters and determine first matching deny rule for affected flow.

ipfw -a list | tail -n 80
route -n get default
netstat -rn

Step-by-Step Diagnosis

Correlate app destination ports with ipfw counters and packet captures.

ipfw -d show
tcpdump -ni  host  -c 60
traceroute 

Solution – Primary Fix

Add explicit keep-state allow rule for required egress and reload policy.

ipfw add 300 allow tcp from me to  443 out keep-state
service ipfw restart
ipfw -a list | grep 300

Solution – Alternative Approaches

Migrate to table-driven allowlists for maintainable outbound policy.

ipfw table 10 add 
ipfw add 310 allow ip from me to table(10) out keep-state

Verification & Acceptance Criteria

Outbound API calls succeed and deny counters stop incrementing for legitimate traffic.

fetch -o /dev/null https://
ipfw -a list | tail -n 40

Rollback Plan

Remove inserted rules and restore previous ruleset snapshot if side effects occur.

ipfw delete 300
ipfw delete 310
service ipfw restart

Prevention & Hardening

Version-control rules and run synthetic egress tests after policy deploys.

ipfw list > /root/ipfw.rules.$(date +%F)
service ipfw check

Related Errors & Cross-Refs

May resemble DNS or proxy outages if only specific ports are filtered.

Related tutorial: View the step-by-step tutorial for FreeBSD 14.

View all FreeBSD 14 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

ipfw manual pages and FreeBSD network filtering best practices.