FreeBSD 13 – sshd refuses to start from invalid sshd_config option – Fix & Prevention

📖 ~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

SSH daemon remains stopped after config changes, cutting off remote administration.

Environment & Reproduction

Usually follows hardening edits with unsupported or misspelled directives.

service sshd status
sshd -t
cat /etc/ssh/sshd_config

Root Cause Analysis

Parser rejects invalid directives and service startup exits with non-zero status.

Quick Triage

Test config syntax and inspect service log output immediately.

sshd -t
service sshd onestatus
tail -n 60 /var/log/messages

Step-by-Step Diagnosis

Locate exact offending line and validate include fragments.

nl -ba /etc/ssh/sshd_config | sed -n '1,200p'
sshd -T | head -n 40
find /etc/ssh -type f -name '*.conf' -maxdepth 2

Solution – Primary Fix

Correct invalid options, validate syntax, and restart sshd safely.

cp -a /etc/ssh/sshd_config /etc/ssh/sshd_config.bak
vi /etc/ssh/sshd_config
sshd -t && service sshd restart

Solution – Alternative Approaches

Reinstall openssh-portable package defaults and reapply vetted hardening baseline.

pkg install -fy openssh-portable
sshd -t

Verification & Acceptance Criteria

sshd is running and key-based logins succeed from management hosts.

service sshd status
ssh -o BatchMode=yes localhost true
last | head

Rollback Plan

Restore backed-up sshd_config if new fixes break compatibility.

cp -a /etc/ssh/sshd_config.bak /etc/ssh/sshd_config
service sshd restart

Prevention & Hardening

Enforce pre-deploy sshd -t checks in automation.

sshd -t

Related Errors & Cross-Refs

Related to pf lockout conditions and home directory permission failures.

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

OpenSSH and FreeBSD service management documentation.