DailyGlimpse

SSH Hardening for Ubuntu 24.04: Ed25519 Keys and Drop-In Configs

Business
May 17, 2026 · 3:14 AM

In this guide, we walk through SSH hardening techniques for Ubuntu 24.04, focusing on Ed25519 keys only, disabling password authentication, preventing root login, using sshd_config.d drop-in files, and implementing Match User blocks. This lesson is part of the "Ubuntu Mastery" course and serves as a bridge to the "SSH Hardening Mastery" series.

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Key steps include:

  • Generate Ed25519 key pairs
  • Configure sshd_config for key-only authentication
  • Disable root login
  • Use drop-in configuration files under /etc/ssh/sshd_config.d/
  • Apply Match User blocks for user-specific settings

For DevOps engineers, sysadmins, and developers, these practices ensure a secure SSH setup.