CentOS Stream 9 – Common Problem 121 – 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

NFSv4 mounts show all files owned by ‘nobody:nobody’ on Stream 9 clients.

Environment & Reproduction

idmapd domain mismatch or rpc.idmapd not running where required.

Root Cause Analysis

Default behaviour with KRB5 sec=sys can fall back to nobody.

Quick Triage

cat /sys/module/nfs/parameters/nfs4_disable_idmapping and check /etc/idmapd.conf.

Step-by-Step Diagnosis

Inspect server export domain vs client /etc/idmapd.conf [General] Domain.

Solution – Primary Fix

Set the same Domain on client and server, then nfsidmap -c; remount.

Solution – Alternative Approaches

Use sec=krb5 with proper Kerberos principals to bypass idmap.

Verification & Acceptance Criteria

ls -l on the mount shows the expected user names.

Rollback Plan

Restore previous /etc/idmapd.conf and remount.

Prevention & Hardening

Centralize idmapd Domain via configuration management.

Related Errors & Cross-Refs

Related: SSSD ID mapping and AD UPN suffixes.

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

nfsv4 idmapd(8) and Red Hat NFS chapter.