SecuryBlack LogoSecuryBlack
← Blog/Security

Fail2ban vs SSH Keys: What Do You Really Need to Secure a VPS?

·8 min read
Fail2ban vs SSH Keys: What Do You Really Need to Secure a VPS?

Any newly provisioned VPS server on Hetzner, DigitalOcean, or AWS receives thousands of automated connection attempts every day. When addressing server security, following a structured VPS hardening and security guide is fundamental to preventing unauthorized access.

In this article, we compare two core defensive mechanisms: exclusive cryptographic SSH key authentication and Fail2ban.

1. Cryptographic SSH keys: The first line of defense

Disabling password authentication (PasswordAuthentication no) and enforcing public/private key pairs completely eliminates traditional dictionary attacks.

  • Advantages: Immune to password-guessing attempts (brute force).
  • Limitations: Does not stop botnets from hitting port 22, creating massive log noise and consuming sshd connection resources.

2. Fail2ban: Active botnet blocking at the firewall

Fail2ban is a security daemon that continuously analyzes system logs (/var/log/auth.log or journalctl). When it detects repeated failed connection attempts from a single IP, it dynamically modifies the firewall (UFW / iptables) to block that IP for a defined period.

  • Advantages: Drastically reduces log noise and frees up CPU/RAM resources.
  • Limitations: If attacks come from distributed botnets (thousands of distinct IPs each making only 1 attempt), Fail2ban alone is less effective.

3. The recommended combination: Automated Hardening

The best practice in production is not choosing one over the other, but combining both:

  1. Enforce SSH Key-Only in /etc/ssh/sshd_config.
  2. Change the default SSH port (optional, but eliminates 95% of automated background scanning).
  3. Enable UFW allowing only strictly necessary ports.
  4. Configure Fail2ban to mitigate connection saturation.

With the Rust-based FerroSentry security agent in SecuryBlack, this hardening process is executed and continuously audited without risking locking yourself out of your server.