Azure Service Endpoint Fundamentals and Best Practices

Azure service endpoints are a fundamental concept in Azure networking, allowing you to control access to your Azure resources from specific virtual networks.

An Azure service endpoint is essentially a gateway that enables communication between your virtual network and Azure services, such as Azure Storage and Azure Cosmos DB.

To create an Azure service endpoint, you need to specify the Azure service and the virtual network you want to connect to it.

You can create multiple service endpoints for different Azure services and virtual networks, giving you flexibility in managing your network traffic.

A private endpoint is a virtual network interface that connects to an Azure service, allowing a network resource, like a virtual machine, to access the service via a private IP address. This connection is private and secured by Azure Private Link.

Private endpoints are deployed to the same region and subscription as the virtual network, and you can create multiple private endpoints on the same or different subnets within the same virtual network.

Clients initiate connections to the private endpoint and related service, but the service cannot establish a connection to the client. Connections are single direction only.

Here are some key notes about private endpoints:

Once you establish a private endpoint for a resource instance, you can disable public access to the resource as an additional security measure.

Configuring private endpoints is a crucial step in setting up Azure service endpoints. You can bring Azure services like storage account services, databases, and key vaults into your virtual network using a private endpoint.

A private endpoint is a virtual network interface that connects to the Azure service, using a dynamically assigned private IP address from the virtual network address range. This network interface keeps the same private IP address for the entire lifecycle of the private endpoint.

To resolve the private IP address to the resource name, you need to create a forwarder in your existing DNS infrastructure or use private DNS zones from Azure. Private DNS zones provide domain name resolution within a virtual network without a custom DNS solution.

You can link private DNS zones to each virtual network to provide DNS services to that network. For example, if you configured a private DNS zone for the storage account blob service, the DNS zone name would be privatelink.blob.core.windows.net.

To configure service endpoints, you need to make changes to the Bicep script and pass virtual network rules as a parameter. This allows you to decide if you want to give access to a specific network or just ignore the parameter and let other settings define the access.

Here are the steps to configure service endpoints:

Note that you don't define a service endpoint on a service level, but rather on a subnet level. This means that two instances of the same service don't necessarily allow the same connection.

Network connectivity is a crucial aspect of Azure Service Endpoints, allowing you to connect your virtual machines to Azure services securely. Service Endpoints provide a secure and private connection to Azure services, enabling you to access resources like storage accounts and Service Bus without exposing them to the public internet.

To check connectivity inside a network, you can use tools like curl to call the HTTP endpoint and get a response. However, if the storage account is not configured to accept connections from the default subnet, you'll still get an error.

You can visualize communication by deploying an additional virtual machine with a network interface attached to the subnet with the service endpoint. If everything is configured correctly, the second virtual machine should have access to the storage account.

Service Endpoints work with any compute resource instance running within the enabled subnet. You can enable multiple service endpoints on a subnet, and limit access to specific regions of a service endpoint-enabled service with service tags.

Here's a summary of the key benefits of Service Endpoints:

Service Endpoints are a powerful tool for securing and managing network connectivity in Azure. By understanding how they work and how to configure them, you can build more secure and reliable applications on the Azure platform.

Azure service endpoint policies provide an additional layer of security for Azure Storage by allowing you to specify which storage accounts a given subnet has access to. This can be a game changer in scenarios where you need to limit access to specific storage accounts.

Service endpoint policies take precedence over other methods of limiting access to Azure Storage, including service or private endpoints. This means that even if a storage account has been whitelisted for connections from a service endpoint subnet, access may still be blocked if a service endpoint policy is in place.

In fact, service endpoint policies can even block access to publicly available services like Azure Storage, as seen in the example where access to the sapublicne storage account was blocked despite being publicly available. This makes service endpoint policies a great data exfiltration prevention method.

Policies are a crucial aspect of security in Azure Storage. Service endpoint policies can provide an additional layer of security by specifying which storage accounts a given subnet has access to.

This feature is quite powerful and can be a game changer in certain scenarios. To get started, you can deploy a service endpoint policy using a definition that accepts a parAllowedStorageAccountId parameter.

Currently, Azure Resource Manager doesn't support creating subnet association for service endpoint policies. To complete the setup, you need to use the Azure Portal, Azure PowerShell, or Azure CLI.

Service endpoint policies take precedence over other methods of limiting access to Azure Storage, which means that access can be blocked even if a storage account has explicitly whitelisted connections from a service endpoint subnet.

This can be seen in the validation script, where access to a storage account is blocked even though it has whitelisted connections. The result can be surprising, but it's a great data exfiltration prevention method.

Service endpoint policies are a separate resource that you assign at the subnet level. They contain definitions that specify an existing Azure resource, such as an Azure Storage account.

Here are some key points to keep in mind when working with service endpoint policies:

Virtual Networks are only supported in Premium tier Service Bus namespaces.

You should be aware that implementing Virtual Networks integration can prevent other Azure services from interacting with Service Bus. This is why you can allow access to Service Bus resources from certain trusted services, even when network service endpoints are enabled.

Here are some Microsoft services that are required to be on a virtual network: Azure Data ExplorerAzure Health Data ServicesAzure ArcAzure KubernetesAzure Machine LearningMicrosoft PurviewMicrosoft Defender for CloudAzure Provider Hub

To allow traffic to your Service Bus namespace, you need to specify at least one IP rule or virtual network rule, so that only traffic from the specified IP addresses or subnet of a virtual network is allowed.

Service endpoints and private endpoints share some similarities, but they also have some key differences. One of the main differences is that service endpoint traffic still connects to the public endpoint of the Azure SQL Database, whereas private endpoint traffic is routed to a private endpoint on the back end.

You can't turn off all public network access to your Azure SQL Database and still use service endpoints. However, you can block out all other traffic by using Azure SQL Database firewall rules or Virtual Network firewall rules, and then allow access via either type of endpoint.

Both service endpoints and private endpoints support turning off the "Allow Azure service and resources to access this server" option on your Azure SQL Database logical server. But keep in mind that private endpoints are charged based on the lifetime of the private endpoint itself, as well as the inbound/outbound data processed over that endpoint.

Here are some key differences between service endpoints and private endpoints:

Private endpoints are a great way to secure your Azure services, but they have some key differences from service endpoints. One major difference is that private endpoints allow you to completely turn off public network access to your Azure SQL Database.

You can create multiple private endpoints on the same or different subnets within the same virtual network. This means you can have multiple private connections to different Azure services.

Private endpoints are metered separately for inbound and outbound data, with the same hourly fee for both directions. From the perspective of the subnet, writing to a database is considered outbound.

Here are some key considerations for private endpoints:

Service endpoints can't be used for securing access from on-premises directly.

If you're trying to access Azure SQL Database from on-premises, you'll need to explore alternative security options.

Service endpoints must reside in the same region as the Azure SQL Database they're accessing.

This means you can't use service endpoints to access a database in a different region, even if it's within the same Azure environment.

DNS entries for Azure services continue to resolve to the public IP address of the service.

This is important to keep in mind when setting up service endpoints, as it may affect how you configure your DNS settings.

Service endpoints work at an Azure SQL Database logical server level, not the individual database level.

This means you'll need to set up service endpoints for the entire server, rather than individual databases.

If a private endpoint is set on the server and you deny public network access, service endpoints will fail.

This can cause issues if you're relying on service endpoints for access to your database, so be sure to plan accordingly.