Effective DevOps (Jennifer Davis and Katherine Daniels)

SSH Tunnels Deep Dive - Local Port Forwarding

Most people only use SSH for logging into a remote machine, and they never look beyond that. But SSH can do far more than provide a secure shell. One of its most powerful but overlooked features is tunneling, the ability to move traffic through an encrypted channel and reach services you normally can’t access.

At first, SSH tunnels feel confusing. That’s normal. Many admins and developers struggle with them until they see them demonstrated in real scenarios and work through them hands-on. That’s the goal of this series: to break down SSH tunneling into clear, practical parts, each one supported by labs you can run on your own machine. All the lab files are available in the GitHub repository.

This series will cover the four major types of SSH tunnels:

• Local Port Forwarding
• Remote Port Forwarding
• Proxy Tunneling through a Bastion Host
• Dynamic Port Forwarding (SOCKS5)

Each part focuses on one pattern, explains when it’s useful, and walks you through a complete lab environment that demonstrates the behaviour step by step.

In this first part, we’ll start with the most familiar one, Local Port Forwarding, and see how a simple SSH connection can give you access to services that would normally be unreachable.