ssh security encryption

How Machines Securely Communicate with Each Other

SSH Series
Posted by Munish Mehta on Monday, January 20, 2025
Have you ever wondered how computers securely talk to each other across the internet, without prying eyes snooping on their conversation? Welcome to the first part of my brand-new blog series, where I would try to demystify SSH—the silent hero of remote server management and secure communication.

This article is part of a series.

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In this series, I am going to describe how SSH keeps data safe, how to harness its power for secure logins, best practices to protect your systems, and advanced techniques for tunnelling and automation. Whether you’re a developer, a budding sysadmin, or just plain curious, this series is for you!

What This Series Will Cover

  1. Introduction to SSH

    • Quick history of SSH and why it replaced telnet
    • Basic terminology and how SSH works under the hood
    • The client-server handshake and key exchange

  2. Setting Up and Using SSH

    • Installing SSH on various operating systems
    • Establishing your first secure connection
    • Navigating files like authorized_keys and known_hosts

  3. SSH Key-Based Authentication

    • Why keys are more secure than passwords
    • Generating SSH keys (RSA, ED25519, etc.)
    • Configuring your server for key-based authentication

  4. SSH Best Practices and Security Hardening

    • Tweaking SSH configuration for maximum security
    • Changing default ports and disabling root login
    • Setting up tools like Fail2Ban and two-factor authentication

  5. Advanced SSH Techniques

    • Port forwarding and tunnelling
    • Using jump hosts (bastion hosts)
    • Leveraging ssh-agent and multiplexing

  6. Troubleshooting Common SSH Issues

    • Diagnosing “connection refused” errors
    • Debugging known host mismatches
    • Checking logs and running SSH in verbose mode

  7. Automating Tasks with SSH

    • Incorporating SSH into scripts and DevOps workflows
    • Handling multiple servers with parallel SSH or Ansible

  8. SSH Alternatives and Enhancements

    • Exploring mosh for improved stability in shaky networks
    • Investigating zero-trust solutions like Teleport
    • Comparing SSH to VPNs

  9. Recap and Final Thoughts

    • Summarizing key takeaways
    • Providing further resources
    • Next steps to expand your SSH knowledge

Have Questions or Stories?

Drop a comment below! I’d love to hear about your experiences—whether it’s your first time hearing about SSH, a nostalgic memory of Telnet’s early days, or advanced tips for modern DevOps setups. Together, we’ll explore how a simple concept—encryption—revolutionized the way the world connects to remote servers.

This article is part of a series.

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