CentOS Stream 9 – Common Problem 247 – Diagnosis and Fix

📖 ~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

auditd misses events under load

Environment & Reproduction

Backlog limit too low for CS9 default audit ruleset.

Root Cause Analysis

audit_backlog_wait_time exhausted and events dropped.

Quick Triage

auditctl -s shows lost > 0 and backlog increasing.

Step-by-Step Diagnosis

Run: sudo auditctl -s; sudo ausearch -m DAEMON_RECONFIG.

Solution – Primary Fix

sudo auditctl -b 32768 and persist via /etc/audit/rules.d/audit.rules with -b.

Solution – Alternative Approaches

Route audit to remote audisp-remote and shrink retained ruleset.

Verification & Acceptance Criteria

auditctl -s shows lost=0 across sustained load.

Rollback Plan

Restore original -b value and restart auditd.

Prevention & Hardening

Baseline lost counter and alert on growth via Prometheus.

Related Errors & Cross-Refs

Pairs with audit: backlog limit exceeded kernel warnings.

Related tutorial: View the step-by-step tutorial for centos-stream-9.

View all centos-stream-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

audit.rules(7) and auditctl(8).