🟠 High   ⏱ 5–30 min  Last verified: 19 May 2026
Affected versions: FreeBSD 15

📖 ~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

Jail startup reports epair/bridge errors and hosted services never bind to network.

Environment & Reproduction

Common after host reboot where bridge creation commands were not persisted.

jls -v
service jail status
ifconfig -a | egrep 'bridge|epair|vnet'

Root Cause Analysis

VNET configuration expects bridge interfaces that do not exist at jail start time.

Quick Triage

Validate jail.conf and host network bootstrap order.

sed -n '1,200p' /etc/jail.conf
sysrc cloned_interfaces
sysrc ifconfig_bridge0

Step-by-Step Diagnosis

Confirm epair creation and attachment steps in logs.

service jail onestart 
dmesg -a | tail -n 120
ifconfig bridge0
Illustrative mockup for freebsd-15 — terminal_or_console
Diagnosis commands for post 158 — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Persist bridge and member configuration in rc.conf, then restart jail service.

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sysrc cloned_interfaces+=' bridge0'
sysrc ifconfig_bridge0='addm  up'
service netif restart
service jail restart
Illustrative mockup for freebsd-15 — log_or_dashboard
Fix validation evidence for post 158 — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

For non-VNET jails, switch to shared IP mode where appropriate.

vi /etc/jail.conf
# set vnet=off and assign ip4.addr
service jail restart

Verification & Acceptance Criteria

Jail starts, receives expected networking, and reaches upstream dependencies.

jexec  ifconfig
jexec  ping -c 3 8.8.8.8
service jail status

Rollback Plan

Revert rc.conf network changes and return to previously functioning jail network model.

sysrc -x ifconfig_bridge0
service netif restart
service jail restart

Prevention & Hardening

Template jail network prerequisites and validate on boot with health checks.

service netif check
ifconfig bridge0
jls

Frequently linked with missing devfs and pf anchor policies for jails.

Related tutorial: View the step-by-step tutorial for freebsd-15.

View all freebsd-15 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

FreeBSD Jail Handbook sections on VNET and bridge networking.

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