Ayodele Aransiola

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Understanding Zero Trust Tunneling for Secure Software Development

January 11, 2026 By Ayodele
DevOps
software development
security
networking

When you build a web application on your local machine, you often need to show it to someone. On another day, you might need to test a webhook from Stripe, demo a new feature to a client, or test how your app looks on a mobile device.

Traditionally, developers leverage tunneling tools to bridge the gap between their private localhost and the public internet. But as security threats evolve, simply opening a "hole" in your firewall is no longer enough.

In this article, you will learn how Zero Trust tunneling works and how it compares to tools like ngrok and Outray.

The "Problem"?

Imagine your local computer is a guest staying in a hotel room. You have an intercom (your local port, example: 3000). You can call the front desk, but no one from the outside can call your room directly.

The hotel security (your Firewall) prevents anyone from going through the halls to find you. In networking, your computer is behind NAT (Network Address Translation). It has a private IP address that the public internet cannot see.

To let people reach you, you need a way to bypass that security without leaving your door wide open.

How Tunneling Tools Works

Tools like ngrok and outray solve the initial problem by using a relay system. This system consists of three main parts:

  1. The Tunnel Client (CLI): A program running on your machine.
  2. The Tunnel Server (Relay): A public server that acts as a middleman between your local machine and the public.
  3. The Transport Layer (OSI Layer 4): The mechanism that links your local server to the relay.

The Relay Mechanism

When you start a tunnel, your local machine initiates an outbound call to the Relay Server. You essentially tell the handler, "I am in Room 201. If anyone calls this public number, route the conversation to me."

Because you started the call, your firewall allows the data to flow back and forth. This is called Firewall Traversal.

Protocol Support: TCP and UDP

Modern tools like Outray use different languages for different tasks. Outray uses a Node.js-based CLI for developer experience and a Golang relay server for high-performance data handling. Because it operates at Layer 4 (the Transport Layer) of the Open Systems Interconnection (OSI) model, it can tunnel more than just web traffic. It supports:

  • HTTP: For standard websites.
  • TCP: For databases or SSH.
  • UDP: For game servers or media streaming.

What is Zero Trust Tunneling?

Most tunnels are often "public by default." If someone guesses your random ngrok or outray URL, they can access your local development server. Zero Trust Tunneling changes the philosophy from "Trust the URL" to "Never Trust, Always Verify." It adds a security layer between the public request and your tunnel.

The Invisible Door

In a Zero Trust model (like Cloudflare Tunnel or Zrok), the relay server does not just pass traffic. It acts as an Identity-Aware Proxy.

Before a request ever reaches your computer, the visitor must prove who they are. The relay checks their identity against a provider like Google, GitHub, or Okta. If they are not authorized, the "door" to your computer remains invisible.

Why Use Zero Trust for Development?

Using a Zero Trust approach offers several advantages over basic relays:

  1. You can share a tunnel link with your team and ensure that only people with your company email address can open it. This prevents "leaked" URLs from becoming security vulnerabilities.

  2. Zero Trust tunnels are outbound-only. Your server reaches out to the network, meaning you have zero open ports for hackers to scan.

  3. Since every user must authenticate, you get a clear trail of who accessed your local environment. You can see exactly which person viewed the demo and at what time.

Choosing the Right Tool

Each tool has a specific place in a developer's workflow: you can check which of the tools works best for your current need (ngrok, outray, cloudflare tunnel, zrok, etc.)

Conclusion

Tunneling is a fundamental skill for developers. Whether you use the ease of ngrok, the open-source flexibility of Outray, or the high security of Zero Trust, understanding the underlying mechanism helps you build more reliably.

By moving toward Zero Trust, you ensure that your local development environment stays as secure as your production infrastructure.

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