The default SSH configuration on most distributions is functional but not production-safe. After managing Linux infrastructure for several years — and finding over 50,000 failed login attempts in a single day’s auth log early in my career — I apply the same hardening steps to every server I manage.
Warning
Never lock yourself out. Always test each change in a separate SSH session before closing your original connection.
Guide Structure
- Key-Based Authentication — replace password auth with cryptographic keys
- SSH Daemon Hardening — production-ready sshd_config
- Two-Factor Authentication — TOTP on top of key auth
- Host-Based Authentication — automated server-to-server trust
- Security Monitoring — fail2ban, connection management, log analysis
- Troubleshooting & Best Practices — common issues, compliance, maintenance