What is a private endpoint?

A private endpoint is a network interface that uses a private IP address from your virtual network. This network interface connects you privately and securely to a service that's powered by Azure Private Link. By enabling a private endpoint, you're bringing the service into your virtual network.

The service could be an Azure service such as:

Private endpoint properties

A private endpoint specifies the following properties:

Property Description
Name A unique name within the resource group.
Subnet The subnet to deploy, where the private IP address is assigned. For subnet requirements, see the Limitations section later in this article.
Private-link resource The private-link resource to connect by using a resource ID or alias, from the list of available types. A unique network identifier is generated for all traffic that's sent to this resource.
Target subresource The subresource to connect. Each private-link resource type has various options to select based on preference.
Connection approval method Automatic or manual. Depending on the Azure role-based access control (RBAC) permissions, your private endpoint can be approved automatically. If you're connecting to a private-link resource without Azure RBAC permissions, use the manual method to allow the owner of the resource to approve the connection.
Request message You can specify a message for requested connections to be approved manually. This message can be used to identify a specific request.
Connection status A read-only property that specifies whether the private endpoint is active. Only private endpoints in an approved state can be used to send traffic. Additional available states:
  • Approved: The connection was automatically or manually approved and is ready to be used.
  • Pending: The connection was created manually and is pending approval by the private-link resource owner.
  • Rejected: The connection was rejected by the private-link resource owner.
  • Disconnected: The connection was removed by the private-link resource owner. The private endpoint becomes informative and should be deleted for cleanup.
  • As you're creating private endpoints, consider the following:

    • Private endpoints enable connectivity between the customers from the same:

      • Virtual network
      • Regionally peered virtual networks
      • Globally peered virtual networks
      • On-premises environments that use VPN or Express Route
      • Services that are powered by Private Link
    • Network connections can be initiated only by clients that are connecting to the private endpoint. Service providers don't have a routing configuration to create connections into service customers. Connections can be established in a single direction only.

    • A read-only network interface is automatically created for the lifecycle of the private endpoint. The interface is assigned a dynamic private IP address from the subnet that maps to the private-link resource. The value of the private IP address remains unchanged for the entire lifecycle of the private endpoint.

    • The private endpoint must be deployed in the same region and subscription as the virtual network.

    • The private-link resource can be deployed in a different region than the one for the virtual network and private endpoint.

    • Multiple private endpoints can be created with the same private-link resource. For a single network using a common DNS server configuration, the recommended practice is to use a single private endpoint for a specified private-link resource. Use this practice to avoid duplicate entries or conflicts in DNS resolution.

    • Multiple private endpoints can be created on the same or different subnets within the same virtual network. There are limits to the number of private endpoints you can create in a subscription. For more information, see Azure limits.

    • The subscription that contains the private link resource must be registered with the Microsoft network resource provider. The subscription that contains the private endpoint must also be registered with the Microsoft network resource provider. For more information, see Azure Resource Providers.

    A private-link resource is the destination target of a specified private endpoint. The following table lists the available resources that support a private endpoint:

    Private-link resource name Resource type Subresources
    Azure App Configuration Microsoft.Appconfiguration/configurationStores configurationStores
    Azure Automation Microsoft.Automation/automationAccounts Webhook, DSCAndHybridWorker
    Azure Cosmos DB Microsoft.AzureCosmosDB/databaseAccounts SQL, MongoDB, Cassandra, Gremlin, Table
    Azure Batch Microsoft.Batch/batchAccounts batchAccount, nodeManagement
    Azure Cache for Redis Microsoft.Cache/Redis redisCache
    Azure Cache for Redis Enterprise Microsoft.Cache/redisEnterprise redisEnterprise
    Azure Cognitive Services Microsoft.CognitiveServices/accounts account
    Azure Managed Disks Microsoft.Compute/diskAccesses managed disk
    Azure Container Registry Microsoft.ContainerRegistry/registries registry
    Azure Kubernetes Service - Kubernetes API Microsoft.ContainerService/managedClusters management
    Azure Data Factory Microsoft.DataFactory/factories dataFactory
    Azure Data Explorer Microsoft.Kusto/clusters cluster
    Azure Database for MariaDB Microsoft.DBforMariaDB/servers mariadbServer
    Azure Database for MySQL Microsoft.DBforMySQL/servers mysqlServer
    Azure Database for PostgreSQL - Single server Microsoft.DBforPostgreSQL/servers postgresqlServer
    Azure Device Provisioning Service Microsoft.Devices/provisioningServices iotDps
    Azure IoT Hub Microsoft.Devices/IotHubs iotHub
    Azure IoT Central Microsoft.IoTCentral/IoTApps IoTApps
    Azure Digital Twins Microsoft.DigitalTwins/digitalTwinsInstances API
    Azure Event Grid Microsoft.EventGrid/domains domain
    Azure Event Grid Microsoft.EventGrid/topics topic
    Azure Event Hub Microsoft.EventHub/namespaces namespace
    Azure HDInsight Microsoft.HDInsight/clusters cluster
    Azure API for FHIR (Fast Healthcare Interoperability Resources) Microsoft.HealthcareApis/services fhir
    Azure Key Vault HSM (hardware security module) Microsoft.Keyvault/managedHSMs HSM
    Azure Key Vault Microsoft.KeyVault/vaults vault
    Azure Machine Learning Microsoft.MachineLearningServices/workspaces amlworkspace
    Azure Migrate Microsoft.Migrate/assessmentProjects project
    Application Gateway Microsoft.Network/applicationgateways application gateway
    Private Link service (your own service) Microsoft.Network/privateLinkServices empty
    Power BI Microsoft.PowerBI/privateLinkServicesForPowerBI Power BI
    Microsoft Purview Microsoft.Purview/accounts account
    Microsoft Purview Microsoft.Purview/accounts portal
    Azure Backup Microsoft.RecoveryServices/vaults vault
    Azure Relay Microsoft.Relay/namespaces namespace
    Azure Cognitive Search Microsoft.Search/searchServices searchService
    Azure Service Bus Microsoft.ServiceBus/namespaces namespace
    Azure SignalR Service Microsoft.SignalRService/SignalR signalr
    Azure SignalR Service Microsoft.SignalRService/webPubSub webpubsub
    Azure SQL Database Microsoft.Sql/servers SQL Server (sqlServer)
    Azure Storage Microsoft.Storage/storageAccounts Blob (blob, blob_secondary)
    Table (table, table_secondary)
    Queue (queue, queue_secondary)
    File (file, file_secondary)
    Web (web, web_secondary)
    Dfs (dfs, dfs_secondary)
    Azure File Sync Microsoft.StorageSync/storageSyncServices File Sync Service
    Azure Synapse Microsoft.Synapse/privateLinkHubs web
    Azure Synapse Analytics Microsoft.Synapse/workspaces Sql, SqlOnDemand, Dev
    Azure App Service Microsoft.Web/hostingEnvironments hosting environment
    Azure App Service Microsoft.Web/sites sites
    Azure Static Web Apps Microsoft.Web/staticSites staticSites
    Azure Media Services Microsoft.Media/mediaservices keydelivery, liveevent, streamingendpoint

    Note

    You can create private endpoints only on a General Purpose v2 (GPv2) storage account.

    Network security of private endpoints

    When you use private endpoints, traffic is secured to a private-link resource. The platform validates network connections, allowing only those that reach the specified private-link resource. To access additional sub-resources within the same Azure service, additional private endpoints with corresponding targets are required. In the case of Azure Storage, for instance, you would need separate private endpoints to access the file and blob sub-resources.

    Private endpoints provide a privately accessible IP address for the Azure service, but do not necessarily restrict public network access to it. Azure App Service and Azure Functions become inaccessible publicly when they are associated with a private endpoint. All other Azure services require additional access controls, however. These controls provide an extra network security layer to your resources, providing protection that helps prevent access to the Azure service associated with the private-link resource.

    Private endpoints support network policies. Network policies enable support for Network Security Groups (NSG), User Defined Routes (UDR), and Application Security Groups (ASG). For more information about enabling network policies for a private endpoint, see Manage network policies for private endpoints. To use an ASG with a private endpoint, see Configure an application security group (ASG) with a private endpoint.

    You can connect to a private-link resource by using the following connection approval methods:

    • Automatically approve: Use this method when you own or have permissions for the specific private-link resource. The required permissions are based on the private-link resource type in the following format:

      Microsoft.<Provider>/<resource_type>/privateEndpointConnectionsApproval/action

    • Manually request: Use this method when you don't have the required permissions and want to request access. An approval workflow will be initiated. The private endpoint and later private-endpoint connections will be created in a Pending state. The private-link resource owner is responsible to approve the connection. After it's approved, the private endpoint is enabled to send traffic normally, as shown in the following approval workflow diagram:

    Diagram of the workflow approval process.

    Over a private-endpoint connection, a private-link resource owner can:

    • Review all private-endpoint connection details.
    • Approve a private-endpoint connection. The corresponding private endpoint will be enabled to send traffic to the private-link resource.
    • Reject a private-endpoint connection. The corresponding private endpoint will be updated to reflect the status.
    • Delete a private-endpoint connection in any state. The corresponding private endpoint will be updated with a disconnected state to reflect the action. The private-endpoint owner can delete only the resource at this point.

    Note

    Only private endpoints in an Approved state can send traffic to a specified private-link resource.

    Connect by using an alias

    An alias is a unique moniker that's generated when a service owner creates a private-link service behind a standard load balancer. Service owners can share this alias offline with consumers of your service.

    The consumers can request a connection to a private-link service by using either the resource URI or the alias. To connect by using the alias, create a private endpoint by using the manual connection approval method. To use the manual connection approval method, set the manual request parameter to True during the private-endpoint create flow. For more information, see New-AzPrivateEndpoint and az network private-endpoint create.

    Note

    This manual request can be auto approved if the consumer's subscription is allow-listed on the provider side. To learn more, go to controlling service access.

    DNS configuration

    The DNS settings that you use to connect to a private-link resource are important. Existing Azure services might already have a DNS configuration you can use when you're connecting over a public endpoint. To connect to the same service over private endpoint, separate DNS settings, often configured via private DNS zones, are required. Ensure that your DNS settings are correct when you use the fully qualified domain name (FQDN) for the connection. The settings must resolve to the private IP address of the private endpoint.

    The network interface associated with the private endpoint contains the information that's required to configure your DNS. The information includes the FQDN and private IP address for a private-link resource.

    For complete, detailed information about recommendations to configure DNS for private endpoints, see Private endpoint DNS configuration.

    Limitations

    The following information lists the known limitations to the use of private endpoints:

    Network security group

    Limitation Description
    Effective routes and security rules unavailable for private endpoint network interface. Effective routes and security rules won't be displayed for the private endpoint NIC in the Azure portal.
    NSG flow logs unsupported. NSG flow logs unavailable for inbound traffic destined for a private endpoint.
    No more than 50 members in an Application Security Group. Fifty is the number of IP Configurations that can be tied to each respective ASG that’s coupled to the NSG on the private endpoint subnet. Connection failures may occur with more than 50 members.
    Destination port ranges supported up to a factor of 250K. Destination port ranges are supported as a multiplication SourceAddressPrefixes, DestinationAddressPrefixes, and DestinationPortRanges.

    Example inbound rule:
    1 source * 1 destination * 4K portRanges = 4K Valid
    10 sources * 10 destinations * 10 portRanges = 1K Valid
    50 sources * 50 destinations * 50 portRanges = 125K Valid
    50 sources * 50 destinations * 100 portRanges = 250K Valid
    100 sources * 100 destinations * 100 portRanges = 1M Invalid, NSG has too many sources/destinations/ports.
    Source port filtering is interpreted as * Source port filtering isn't actively used as valid scenario of traffic filtering for traffic destined to a private endpoint.
    Feature unavailable in select regions. Currently unavailable in the following regions:
    West India
    Australia Central 2
    South Africa West
    Brazil Southeast

    NSG additional considerations

    • Outbound traffic denied from a private endpoint isn't a valid scenario, as the service provider can't originate traffic.

    • The following services may require all destination ports to be open when leveraging a private endpoint and adding NSG security filters:

    UDR

    Limitation Description
    SNAT is recommended at all times. Due to the variable nature of the private endpoint data-plane, it's recommended to SNAT traffic destined to a private endpoint to ensure return traffic is honored.
    Feature unavailable in select regions. Currently unavailable in the following regions:
    West India
    UK North
    UK South 2
    Australia Central 2
    South Africa West
    Brazil Southeast

    Application security group

    Limitation Description
    Feature unavailable in select regions. Currently unavailable in the following regions:
    West India
    UK North
    UK South 2
    Australia Central 2
    South Africa West
    Brazil Southeast

    Next steps