Go (net/http and Chi)

This guide will walk you through installing and setting up Zen Firewall by Aikido for your application. Follow the steps below to protect your application.

If you encounter any issues or problems, don't hesitate reach out on support chat or Github issues

https://github.com/AikidoSec/firewall-go

Requirements

• Go 1.24+.

• net/http or Chi

• Aikido account & Zen Firewall token

Installation & Configuration

1

Install Zen Firewall by Aikido

In your application module (the module that contains main), initialize Zen and update dependencies:

go run github.com/AikidoSec/firewall-go/cmd/zen-go@latest init
go mod tidy

Enable Zen as early as possible in your main package:

import "github.com/AikidoSec/firewall-go/zen"

func main() {
    err := zen.Protect()
    if err != nil {
        panic(err)
    }

    // your existing setup
}

Install the build tool and build with toolexec so Zen can instrument your binary:

go install github.com/AikidoSec/firewall-go/cmd/zen-go@latest
go build -toolexec="zen-go" -o bin/app

Set your token at runtime:

export AIKIDO_TOKEN=AIK_RUNTIME_

2

Start Zen Firewall in dry / detection-only mode

Start your app with detection mode enabled:

AIKIDO_BLOCK=false AIKIDO_TOKEN=AIK_RUNTIME_ go run .

Set the token as an environment variable so the Aikido Zen agent can pick it up. If you don't have a token yet, follow instructions here.

AIKIDO_TOKEN=AIK_RUNTIME_

We recommend to start your app in dry mode to ensure it works as expected without blocking any requests. We advise running Zen Firewall in staging for two weeks to avoid false positives.

AIKIDO_BLOCK=false

You can use AIKIDO_DEBUG=true to enable debug mode for more detailed information about what the agent is doing. For more information about your environment variables: Configuration via Environment Variables

3

Test your app

Browse to your application and perform a couple of actions or open a couple of pages. Zen will automatically discover the routes in your application.

You can verify a working agent by looking at the following pages of your Zen application:

• Events: Should show an "Application started" event.

• Routes: After some time your application routes will start showing here with the method, route and requests.

• Instances: Should show the number of active instances for your application where Zen is installed.

4

Enable Rate limiting and User blocking

If you want to use user-blocking, know which user performed an attack and rate-limit on a user basis, set the user using the following function. It's advised to do this in your authentication middleware, and before you add the Aikido middleware.

// Setting a user:
zen.SetUser(r.Context(), id, name)

To use rate-limiting or user-blocking, add the following middleware:

// ...
handler := AikidoMiddleware(mux)
// ...
func AikidoMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		blockResult := zen.ShouldBlockRequest(r.Context())
		if blockResult != nil {
			switch blockResult.Type {
			case "rate-limited":
				message := "You are rate limited by Zen."
				if blockResult.Trigger == "ip" {
					message += " (Your IP: " + *blockResult.IP + ")"
				}
				http.Error(w, message, http.StatusTooManyRequests)
				return
			case "blocked":
				http.Error(w, "You are blocked by Zen.", http.StatusForbidden)
				return
			}
		}

		next.ServeHTTP(w, r)
	})
}

5

Setup rate limiting in the dashboard

After you've added the Zen Firewall middleware, you can test it out by logging in to your Aikido account and navigating to the Zen dashboard.

Agent start event logged with info severity and timestamp shown.

To protect a route from brute force attacks, set up rate limiting in the Aikido Dashboard:

1. Click on the created app.

2. Go to the Routes tab.

3. Find the route you would like to limit and click Setup rate limiting.

4. Follow the instructions to configure the rate limit (e.g., 5 requests per minute).

API route management interface showing authentication routes with protection and rate limiting options.

Set rate limiting for POST /auth/login to 5 requests per minute.

Verify Rate Limiting

Start your app and try to access the route you've rate limited 5 times within a minute. After the fifth attempt, you should receive a rate limit error:

You are rate limited by Aikido firewall. (Your IP: 1.2.3.4)

6

Next steps

Congrats you've successfully installed Zen Firewall. If you encountered any problems, have concerns or feature requests, don't hesitate to reach out to support.

You can now go and explore the many features that Zen Firewall provides:

• Blocking Bot traffic with Zen Firewall

• Blocking or Monitoring Tor traffic with Zen Firewall

• Blocking Users with Zen Firewall

• Blocking Known Threat Actors with Zen Firewall

• Blocking Traffic by Country with Zen Firewall

• Setting Up Rate Limiting for Routes

• Monitor Outbound Domains

Additional information:

• Zen Performance & Reliability

• Blocking vs Detection Mode in Zen Firewall

• Understanding Your Zen Statistics