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Exercise - Restrict access to Azure Storage by using service endpoints

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As the solution architect, you're planning to move sensitive engineering diagram files into Azure Storage. The files must only be accessible from computers inside the corporate network. You want to create a virtual network service endpoint for Azure Storage to secure the connectivity to your storage accounts.

In this unit, you'll create a service endpoint and use network rules to restrict access to Azure Storage. You'll create a virtual network service endpoint for Azure Storage on the Databases subnet. You'll then verify that your DataServer VM can access Azure Storage. Lastly, you'll check that the AppServer VM, which is on a different subnet, can't access storage.

Add rules to the network security group

Here, you'll ensure that communications with Azure Storage pass through the service endpoint. You'll add outbound rules to allow access to the Storage service, but deny all other internet traffic.

1. To create an outbound rule to allow access to Storage, run the following command in Cloud Shell:

   az network nsg rule create \
       --resource-group $rg \
       --nsg-name ERP-SERVERS-NSG \
       --name Allow_Storage \
       --priority 190 \
       --direction Outbound \
       --source-address-prefixes "VirtualNetwork" \
       --source-port-ranges '*' \
       --destination-address-prefixes "Storage" \
       --destination-port-ranges '*' \
       --access Allow \
       --protocol '*' \
       --description "Allow access to Azure Storage"
   

2. To create an outbound rule to deny all internet access, run the following command in Cloud Shell:

   az network nsg rule create \
       --resource-group $rg \
       --nsg-name ERP-SERVERS-NSG \
       --name Deny_Internet \
       --priority 200 \
       --direction Outbound \
       --source-address-prefixes "VirtualNetwork" \
       --source-port-ranges '*' \
       --destination-address-prefixes "Internet" \
       --destination-port-ranges '*' \
       --access Deny \
       --protocol '*' \
       --description "Deny access to Internet."
   

You should now have the following rules in ERP-SERVERS-NSG:

Rule name	Direction	Priority	Purpose
AllowSSHRule	Inbound	100	Allow inbound SSH
httpRule	Inbound	150	Deny from DataServer to AppServer on 80
Allow_Storage	Outbound	190	Allow access to Azure Storage
Deny_Internet	Outbound	200	Deny access to Internet from VNet

At this point, both AppServer and DataServer have access to the Azure Storage service.

Configure storage account and file share

In this step, you'll create a new storage account, then add an Azure file share to this account. This file share is where you'll store your engineering diagrams.

1. To create a storage account for engineering documents, run the following command in Cloud Shell:

   STORAGEACCT=$(az storage account create \
                   --resource-group $rg \
                   --name engineeringdocs$RANDOM \
                   --sku Standard_LRS \
                   --query "name" | tr -d '"')
   

2. To store your storage account's primary key in a variable, run the following command in Cloud Shell:

   STORAGEKEY=$(az storage account keys list \
                   --resource-group $rg \
                   --account-name $STORAGEACCT \
                   --query "[0].value" | tr -d '"')
   

3. To create an Azure file share called erp-data-share, run the following command in Cloud Shell:

   az storage share create \
       --account-name $STORAGEACCT \
       --account-key $STORAGEKEY \
       --name "erp-data-share"
   

Enable the service endpoint

You now need to configure the storage account to be accessible only from database servers by assigning the storage endpoint to the Databases subnet. You then need to add a security rule to the storage account.

1. To assign the Microsoft.Storage endpoint to the subnet, run the following command in Cloud Shell:

   az network vnet subnet update \
       --vnet-name ERP-servers \
       --resource-group $rg \
       --name Databases \
       --service-endpoints Microsoft.Storage
   

2. To deny all access, change the default action to Deny by running the following command in Cloud Shell. After network access is denied, the storage account isn't accessible from any network.

   az storage account update \
       --resource-group $rg \
       --name $STORAGEACCT \
       --default-action Deny
   

3. To restrict access to the storage account, run the following command in Cloud Shell. By default, storage accounts are open to accept all traffic. You want only traffic from the Databases subnet to be able to access the storage.

   az storage account network-rule add \
       --resource-group $rg \
       --account-name $STORAGEACCT \
       --vnet-name ERP-servers \
       --subnet Databases
   

Test access to storage resources

In this step, you'll connect to both of your servers and verify that only DataServer has access to the Azure file share on the storage account.

1. To save the public IP addresses of AppServer and DataServer to variables, run the following command in Cloud Shell:

   APPSERVERIP="$(az vm list-ip-addresses \
                       --resource-group $rg \
                       --name AppServer \
                       --query "[].virtualMachine.network.publicIpAddresses[*].ipAddress" \
                       --output tsv)"
   
   DATASERVERIP="$(az vm list-ip-addresses \
                       --resource-group $rg \
                       --name DataServer \
                       --query "[].virtualMachine.network.publicIpAddresses[*].ipAddress" \
                       --output tsv)"
   

2. To connect to your AppServer VM and attempt to mount the Azure file share, run the following command in Cloud Shell:

   ssh -t azureuser@$APPSERVERIP \
       "mkdir azureshare; \
       sudo mount -t cifs //$STORAGEACCT.file.core.windows.net/erp-data-share azureshare \
       -o vers=3.0,username=$STORAGEACCT,password=$STORAGEKEY,dir_mode=0777,file_mode=0777,sec=ntlmssp; findmnt \
       -t cifs; exit; bash"
   

3. Enter the password you used when you created the VM.

4. The response should include a mount error message. This connection isn't allowed because there's no service endpoint for the storage account on the Applications subnet.

5. To connect to your DataServer VM and attempt to mount the Azure file share, run the following command in Cloud Shell:

   ssh -t azureuser@$DATASERVERIP \
       "mkdir azureshare; \
       sudo mount -t cifs //$STORAGEACCT.file.core.windows.net/erp-data-share azureshare \
       -o vers=3.0,username=$STORAGEACCT,password=$STORAGEKEY,dir_mode=0777,file_mode=0777,sec=ntlmssp;findmnt \
       -t cifs; exit; bash"
   

6. Enter the password you used when you created the VM.

7. The mount should succeed, and the response should include details of the mount point. This is allowed because you created the service endpoint for the storage account on the Databases subnet.

By using the storage service endpoint on the Databases subnet, you've now verified that DataServer can access storage. You've also verified that AppServer can't access storage. This is because this server is on a different subnet and doesn't have access to the virtual network service endpoint.

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