Debian 13 – SSH login denied due to strict permissions in ~/.ssh – 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

Valid SSH keys are rejected, blocking administrative access and automation that relies on key auth.

Environment & Reproduction

Appears on Debian 13 after user home migrations or incorrect backup restore permissions.

Root Cause Analysis

OpenSSH refuses key auth when ~/.ssh, authorized_keys, or parent directory permissions are too permissive.

Quick Triage

Check auth logs and file ownership/mode before rotating keys or changing daemon settings.

Step-by-Step Diagnosis

Validate UID/GID ownership and permissions from home directory down to authorized_keys.

Solution – Primary Fix

Apply strict ownership and mode values, then retry key auth and confirm sshd policy alignment.

Solution – Alternative Approaches

Use centralized authorized key management to avoid manual drift on fleet nodes.

Verification & Acceptance Criteria

Key-based login succeeds and sshd logs no permission-related rejections.

Rollback Plan

Reinstate prior ownership values if user mapping changes require staged migration updates.

Prevention & Hardening

Enforce filesystem permission baselines with periodic compliance checks.

Related Errors & Cross-Refs

Related errors include SELinux/AppArmor denials and unsupported key algorithm policies.

Related tutorial: View the step-by-step tutorial for Debian 13.

View all Debian 13 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

OpenSSH hardening documentation and Debian sshd defaults for user key authentication.