Introduction

VPS SSH login fails when public key not in authorized_keys or permissions incorrect. This guide provides step-by-step diagnosis and resolution.

Symptoms

Typical error output:

bash
Permission denied (publickey)
Server refused our key
Authentication failed: publickey not in authorized_keys or permissions incorrect

Common Causes

  1. 1.Account quota or resource limit exceeded
  2. 2.Permission or authentication configuration issue
  3. 3.Service not running or configuration error
  4. 4.SSL certificate or domain validation issue

Step-by-Step Fix

Step 1: Check Current State

bash
# Check service status
systemctl status apache2 nginx php-fpm
# View error logs
tail -f /var/log/error.log
# Check disk usage
df -h

Step 2: Identify Root Cause

bash
# Check account limits
# Hosting panel > Account > Resource Usage
# View service logs
tail -f /var/log/apache2/error.log
# Check disk and memory
free -m && df -h

Step 3: Apply Primary Fix

```bash # Primary fix: Check limits and restart # Check account quotas in hosting panel # Verify disk usage df -h

# Restart failed service systemctl restart apache2

# Clear logs if disk full rm -f /var/log/*.log.old ```

Step 4: Apply Alternative Fix

bash
# Alternative: Contact support
# Check hosting panel > Account > Limits
# Submit support ticket with:
# - Error message
# - Timestamp
# - Steps attempted

Step 5: Verify the Fix

bash
curl -I https://yourdomain.com
# Should return 200 OK
df -h
# Check disk space is available

Common Pitfalls

  • Not monitoring account resource usage
  • Ignoring disk space warnings
  • Using incorrect file permissions
  • Not renewing SSL certificates before expiry

Best Practices

  • Monitor resource usage in hosting panel
  • Set up alerts for quota warnings
  • Keep SSL certificates renewed
  • Maintain backup of configurations
  • Hosting Quota Exceeded
  • Permission Denied
  • Service Not Running
  • SSL Certificate Error