Create and configure Azure Application Gateway

Azure Application Gateway is a web traffic load balancer that enables you to manage traffic to your web applications. Traditional load balancers operate at the transport layer (OSI layer 4 – TCP and UDP) and route traffic based on source IP address and port, to a destination IP address and port. However, the Application Gateway is more advanced as it includes routing based on additional attributes such as URI path or host headers. For any Azure Security Engineer preparing for the AZ-500 Microsoft Azure Security Technologies exam, understanding how to create and configure an Azure Application Gateway is essential.

To create and configure an Azure Application Gateway, one must complete the following steps:

1. Creation of Application Gateway:

• Navigate to the Azure portal.
• Search for and select “Application Gateways” in the search bar.
• Click on “Add” to create a new Application Gateway.

2. Basic Configuration:

• Provide a name for your Application Gateway instance.
• Select a desired subscription and resource group where you want to deploy Application Gateway.
• Choose the desired region that is closest to your users to minimize latency.

3. Virtual Network:

• You need to select or create a virtual network (VNet) for the Application Gateway.
• Application Gateway must have a dedicated subnet.

4. Size and Scale:

• Choose a size for the Application Gateway (small, medium, large) or use the Autoscale option for auto-scaling the deployment based on the load.
• Define the number of instances, if not using Autoscale.

5. Configuration:

• Listeners: These are required to handle incoming traffic. Set up listeners for the protocols you require (HTTP, HTTPS).
• Rules: Configure the routing rules that determine how incoming traffic should be redirected.
• HTTP settings: Adjust the settings that control the behaviour of the gateway in terms of connection draining, cookie-based affinity, and timeout settings.
• Backend pools: Define the backend pools which consist of IP addresses or FQDNs of the web servers that your Application Gateway needs to route the traffic to.

6. SSL termination (if using HTTPS):

• If you are using SSL for your applications, you need to set up SSL termination on the Application Gateway to offload SSL encryption/decryption from your web servers, which can be CPU-intensive. This involves uploading a certificate and binding it to an HTTPS listener.

7. Web Application Firewall (WAF) Configuration:

• If you need to protect your web applications more thoroughly, Application Gateway supports WAF, which provides centralized, inbound protection for your web applications against common exploits and vulnerabilities.
• There are two WAF modes: Detection mode and Prevention mode. Detection mode logs all threat alerts without blocking them, while Prevention mode blocks intrusions and attacks.
• Configure WAF policies with custom rules if necessary.

8. Monitoring:

• Enable logging and monitoring of the Application Gateway using Azure Monitor, Log Analytics, or Network Watcher for better visibility into its operation and performance.

9. Pricing:

• Review the pricing tier options and associated features. There might be additional charges for enabled features such as WAF.

10. Review and Create:

• Review all settings and create the Application Gateway. Azure will validate your configurations before the creation process starts.

Example Scenario:

Let’s assume that you want to configure an Azure Application Gateway for a web application that must support both HTTP and HTTPS traffic, includes URL-based routing, and requires high-availability with autoscaling.

In this scenario, you’d set up two listeners (one for HTTP and one for HTTPS), assign a WAF policy for security, enable autoscaling for high availability, and configure URL-based routing rules to ensure proper traffic distribution to different backend pools depending on the URL path requested.

The following table summarizes the key components and their purposes within the Application Gateway configuration:

Summary:

Understanding and properly configuring Azure Application Gateway is central to managing web traffic and ensuring security in a cloud environment. An Azure Security Engineer should understand the implications of each setting and component of Application Gateway, be skilled at configuring it to meet the specific requirements of an application, and enable security features like WAF to protect against threats. This expertise is pivotal in passing the AZ-500 Microsoft Azure Security Technologies exam and effectively securing Azure web applications.