CentOS Stream 10 – Common Problem 245 – 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

Files exported over NFSv4 appear owned by nobody:nobody on the client, blocking POSIX permission checks.

Environment & Reproduction

Common when /etc/idmapd.conf Domain or sssd_nss is misaligned between client and server.

Root Cause Analysis

NFSv4 maps user@domain strings; mismatched Domain values trigger fallback to nobody mapping.

Quick Triage

Check /etc/idmapd.conf Domain on both sides and nfsidmap -d output for the active domain.

Step-by-Step Diagnosis

Run: nfsidmap -d; cat /etc/idmapd.conf; rpc.idmapd -vvv -f.

Solution – Primary Fix

Set identical Domain in /etc/idmapd.conf, restart nfs-idmapd, and run nfsidmap -c to clear cache.

Solution – Alternative Approaches

Use NFSv4 with sec=krb5 plus AD-integrated SSSD to avoid local idmap files entirely.

Verification & Acceptance Criteria

ls -l on the client shows expected UIDs and writes obey POSIX ownership and permissions.

Rollback Plan

Restore previous /etc/idmapd.conf and reboot nfs-idmapd if applications regress.

Prevention & Hardening

Standardise idmap Domain in build automation and validate during integration tests.

Related Errors & Cross-Refs

Related to NFSv4 ACL translation issues and FreeIPA trust mapping problems.

Related tutorial: View the step-by-step tutorial for centos-stream-10.

View all centos-stream-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

nfsidmap(8) and Red Hat NFS administration guide.