Tutorial / Cram Notes
By properly configuring network isolation, you can significantly reduce the surface area for potential attacks and ensure that your applications are accessible only to authorized traffic.
Configuring Network Isolation for Azure Web Apps
Azure App Service Environment (ASE) provides an isolated and dedicated environment to run Azure Web Apps, ensuring the highest level of network isolation. However, not every scenario requires an ASE due to its cost and complexity. For more common scenarios, you can achieve network isolation using Service Endpoints, Azure App Service Environment (not to be confused with ASE), and Virtual Network (VNet) Integration.
Service Endpoints:
Service Endpoints enable you to restrict access to Azure Web Apps from specific subnets within a virtual network. Here’s how to set it up:
- Go to the Azure portal and navigate to your Web App.
- Under Settings, select ‘Networking’.
- Click ‘Configure your VNet’ to integrate with a VNet.
- Once the VNet is integrated, enable Service Endpoints.
- Choose the necessary Azure services and regions.
VNet Integration:
With VNet Integration, you can protect your web apps by only allowing access to them from your VNet. This helps ensure that the apps are not exposed to the public internet.
- Navigate to your Web App in the Azure portal.
- Select ‘Networking’ and click on ‘VNet Integration’.
- Choose the VNet to integrate with your Web App.
- Add the Web App to a subnet within the selected VNet.
This configuration enables your Web Apps to communicate securely with resources in your VNet but does not restrict inbound access from the internet. To do so, you need to combine it with Access Restriction rules.
Access Restrictions:
To explicitly deny or allow traffic, you can use access restriction rules:
- Within the ‘Networking’ section of your Web App settings, click ‘Access Restrictions’.
- Add a new rule, providing a priority, name, and specifying the action (Allow/Deny).
- Define the IP address or range to be allowed or denied.
Configuring Network Isolation for Azure Functions
Azure Functions can also benefit from similar network isolation mechanisms, especially when hosting critical applications.
VNet Integration (For Function Apps on a Premium Plan):
- Go to your Function App in the Azure portal.
- Under Platform Features, choose ‘Networking’ > ‘VNet Integration’.
- Connect to an existing VNet or create a new one.
- Assign the Function App to a specific subnet dedicated to your functions.
This ensures that your function apps can access resources within the VNet but remain isolated from direct internet access.
Access Restrictions:
Function Apps also support access restrictions to control incoming traffic.
- Navigate to the Function App settings and click ‘Networking’.
- Within the ‘Networking’ menu, click ‘Access Restrictions’.
- Add allow or deny rules specifying IP address ranges that should be accepted or rejected.
While Service Endpoints are not directly applicable to Function Apps like they are for Web Apps, you can still leverage them by using Azure Functions within an App Service Environment.
Azure Functions in an App Service Environment (ASE):
You can run Azure Functions within an ASE, offering full network isolation and higher scalability.
- Create an ASE within your Azure environment.
- Deploy your function app into the ASE.
- Configure the ASE internal load balancer (ILB) for private network access.
When running in an ASE, your functions will inherit VNet Integration and can be further secured using Network Security Groups or Azure Firewall for complete network isolation.
Comparison
| Feature | Azure Web Apps | Azure Functions |
|---|---|---|
| VNet Integration | Supported | Supported (for Premium Plan) |
| Access Restrictions | Supported | Supported |
| Service Endpoints | Supported | Indirectly via ASE |
| ASE | Optional | Required for maximum isolation |
| Network Security Group (NSG) | Can be applied to Subnet | Can be applied to Subnet |
| Azure Firewall | Can be integrated | Can be integrated |
In conclusion, configuring network isolation for Azure Web Apps and Azure Functions is a crucial security measure. By employing strategies like VNet Integration, Access Restrictions, and deployment within an ASE, you can ensure that your services are available only to the intended audience and protect against common network-related threats.
Practice Test with Explanation
True or False: Azure Web Apps are automatically isolated from other Azure services without any additional configuration.
- Answer: False
By default, Azure Web Apps are not isolated from other services. You must configure network isolation features like VNet Integration, App Service Environment, or use Service Endpoints to isolate your web app.
A Service Endpoint can be used to:
- A) Restrict access to Azure SQL Database from an Azure Web App.
- B) Enable a hybrid connection between Azure Functions and an on-premises server.
- C) Isolate network traffic between an Azure Web App and Azure Blob storage.
- D) Increase the availability of an Azure Function App by deploying to multiple regions.
Answer: A, C
Service Endpoints are used to secure Azure service resources to only your virtual network, thereby restricting access, and they can be configured with Azure SQL Database and Azure storage accounts.
An Azure Function App can be integrated directly into a Virtual Network (VNet).
- Answer: True
Azure Functions can be integrated directly into a VNet using VNet Integration, allowing for network isolation and secure access to resources within the VNet.
True or False: Azure App Service Environment is the only way to isolate network traffic for Azure Web Apps.
- Answer: False
While Azure App Service Environment provides a high level of network isolation, it’s not the only way. You can also use features like VNet Integration and Service Endpoints to isolate network traffic.
The feature that enables Azure Web Apps to access resources in an Azure Virtual Network is called:
- A) VNet Peering
- B) VNet Integration
- C) ExpressRoute
- D) VPN Gateway
Answer: B
VNet Integration allows Azure Web Apps to securely access resources in a VNet.
Which Azure feature helps to integrate Azure Functions with on-premises resources securely?
- A) Hybrid Connections
- B) VPN Gateway
- C) Azure Relay
- D) Network Security Groups
Answer: A
Hybrid Connections is a feature in Azure Functions and Web Apps that provides a secure way to access on-premises resources.
True or False: Azure Private Endpoints enable private connectivity to Azure Web Apps from within a Virtual Network.
- Answer: True
Private Endpoints create a private IP in a VNet for your Azure service, allowing secure and private connectivity from within the VNet.
Network Security Groups (NSGs) can be associated with which of the following to control inbound and outbound traffic to Azure Functions?
- A) Virtual Networks
- B) Subnets
- C) Private Endpoints
- D) All of the above
Answer: D
NSGs can be associated with Virtual Networks, Subnets, and Private Endpoints to filter network traffic to and from Azure resources like Azure Functions.
True or False: Azure Front Door provides network isolation for Web Apps and Azure Functions.
- Answer: False
Azure Front Door is primarily a scaling and routing mechanism. It does not provide network isolation but can be combined with other services that do.
What does an App Service Environment (ASE) provide in terms of network isolation?
- A) An isolated and private environment hosted in a customer’s Virtual Network.
- B) Encryption in transit for all data with no additional configuration.
- C) Direct integration with Azure Front Door for global distribution.
- D) Automatic scaling to handle high traffic loads.
Answer: A
An App Service Environment provides an isolated and private environment fully contained within a customer’s Virtual Network, offering a high level of network isolation.
True or False: It is necessary to open outbound ports on the Azure Function app’s underlying infrastructure to allow outbound traffic in a VNet-integrated setup.
- Answer: False
In a VNet-integrated setup, the infrastructure underlying the Azure Function app is managed by Azure, and appropriate outbound connections are allowed without manually opening outbound ports.
Which of the following is a valid use case for Azure Private Link with Azure Functions?
- A) To expose Azure Functions to the public internet with an assigned public IP
- B) To connect Azure Functions to other Azure resources privately
- C) To integrate Azure Functions with a Content Delivery Network (CDN)
- D) To automatically scale Azure Functions based on CPU usage
Answer: B
Azure Private Link provides private connectivity from Azure Functions to other Azure resources, keeping traffic within the Microsoft network and not exposing it to the public internet.
Great Post! Very informative about configuring network isolation for Web Apps and Azure Functions.
Can someone explain how VNet integration is different for Azure Functions and Web Apps?
Thanks for sharing this guide. It really helped me understand the isolation procedures.
A bit confusing in some parts, but overall a good resource. Could use more diagrams.
Can you use Service Endpoints for securing both Web Apps and Azure Functions?
What are the limitations of using Private Endpoints with Azure Functions compared to Web Apps?
Are there any best practices for configuring network isolation?
I appreciate the detailed breakdown on using network security groups along with VNet integration.