FreeBSD 12 – jail fails to start because VNET bridge interface is missing

📖 ~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

VNET jail startup fails and hosted services remain offline.

Environment & Reproduction

Common after reboot when bridge creation is not persisted.

Root Cause Analysis

jail.conf expects bridge resources that do not exist at start time.

Quick Triage

Check cloned_interfaces, bridge member settings, and jail flags.

Step-by-Step Diagnosis

Review jail startup output and host interface inventory.

Solution – Primary Fix

Persist bridge config in rc.conf and restart netif then jail.

Solution – Alternative Approaches

Switch to non-VNET jail networking where architecture allows.

Verification & Acceptance Criteria

Jail starts, gets network reachability, and passes service checks.

Rollback Plan

Revert network config to prior known-good jail model.

Prevention & Hardening

Template host network prerequisites for all VNET jails.

Related Errors & Cross-Refs

Often appears with missing devfs and firewall jail anchors.

Related tutorial: View the step-by-step tutorial for FreeBSD 12.

View all FreeBSD 12 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

FreeBSD Jail Handbook VNET and bridge sections.