📖 ~1 min read
Table of contents
Symptom & Impact
Valid users cannot log in via SSH, causing operations lockout and delayed incident response.
Environment & Reproduction
Triggered by edits to login.conf or capability database rebuild mistakes.
Root Cause Analysis
An invalid capability entry enforces impossible resource limits or shell restrictions during session setup.
Quick Triage
Use console access, verify account class mapping, and inspect recent auth-related changes.
Step-by-Step Diagnosis
Review authentication logs and login class database output to locate malformed capability records.
Solution – Primary Fix
Correct login.conf entry, rebuild capability DB, and validate SSH session creation.
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Solution – Alternative Approaches
Temporarily assign affected users to a safe default class while full policy is repaired.
Verification & Acceptance Criteria
Interactive and key-based SSH logins succeed with expected session limits and shell behavior.
Rollback Plan
Restore previous login.conf and capability database snapshot if corrected policy still fails.
Prevention & Hardening
Apply syntax checks and staged rollout for authentication policy changes.
Related Errors & Cross-Refs
Can coincide with PAM stack edits and shell path mismatches in user records.
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
login.conf and cap_mkdb man pages plus FreeBSD security handbook content.
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