Tutorial: Integrate a NAT gateway with an internal load balancer using the Azure portal

In this tutorial, you learn how to integrate a NAT gateway with an internal load balancer.

By default, an Azure Standard Load Balancer is secure. Outbound connectivity is explicitly defined by enabling outbound SNAT (Source Network Address Translation).

SNAT is enabled for an internal backend pool via another public load balancer, network routing, or a public IP defined on a virtual machine.

The NAT gateway integration replaces the need for the deployment of a public load balancer, network routing, or a public IP defined on a virtual machine in the backend pool.

In this tutorial, you learn how to:

Prerequisites

An Azure account with an active subscription. Create an account for free.

Create a resource group

Create a resource group to contain all resources for this quickstart.

1. Sign in to the Azure portal.

2. In the search box at the top of the portal enter Resource group. Select Resource groups in the search results.

3. Select + Create.

4. In the Basics tab of Create a resource group, enter, or select the following information.

   Setting	Value
   Subscription	Select your subscription
   Resource group	test-rg
   Region	East US 2

5. Select Review + create.

6. Select Create.

Create the virtual network

1. In the search box at the top of the Azure portal, enter Virtual network. Select Virtual networks in the search results.

2. Select Create.

3. Enter or select the following information in the Basics tab of Create virtual network.

   Setting	Value
   Project details
   Subscription	Select your subscription.
   Resource group	Select test-rg or your resource group.
   Instance details
   Name	Enter vnet-1.
   Region	Select your region. This example uses East US 2.

4. Select the IP Addresses tab, or select Next: Security, then Next: IP Addresses.

5. In Subnets select the default subnet.

6. Enter or select the following information in Edit subnet.

   Setting	Value
   Subnet purpose	Leave the default.
   Name	Enter subnet-1.

7. Leave the rest of the settings as default, then select Save.

8. Select + Add a subnet.

9. In Add a subnet enter or select the following information.

   Setting	Value
   Subnet purpose	Select Azure Bastion.

10. Leave the rest of the settings as default, then select Add.

11. Select Review + create, then select Create.

Create Azure Bastion host

Create an Azure Bastion host to securely connect to the virtual machine.

1. In the search box at the top of the Azure portal, enter Bastion. Select Bastions in the search results.

2. Select Create.

3. Enter or select the following information in the Basics tab of Create a Bastion.

   Setting	Value
   Project details
   Subscription	Select your subscription.
   Resource group	Select test-rg or your resource group.
   Instance details
   Name	Enter bastion.
   Region	Select your region. This example uses East US 2.
   Tier	Select Developer.
   Virtual network	Select vnet-1.
   Subnet	Select AzureBastionSubnet.

4. Select Review + create, then select Create.

Create a NAT gateway

1. In the search box at the top of the Azure portal, enter Public IP address. Select Public IP addresses in the search results.

2. Select Create.

3. Enter the following information in Create public IP address.

   Setting	Value
   Subscription	Select your subscription.
   Resource group	Select your resource group. The example uses test-rg.
   Region	Select a region. This example uses East US 2.
   Name	Enter public-ip-nat.
   IP version	Select IPv4.
   SKU	Select Standard.
   Availability zone	Select Zone-redundant.
   Tier	Select Regional.

4. Select Review + create and then select Create.

5. In the search box at the top of the Azure portal, enter NAT gateway. Select NAT gateways in the search results.

6. Select Create.

7. Enter or select the following information in the Basics tab of Create network address translation (NAT) gateway.

   Setting	Value
   Project details
   Subscription	Select your subscription.
   Resource group	Select test-rg or your resource group.
   Instance details
   NAT gateway name	Enter nat-gateway.
   Region	Select your region. This example uses East US 2.
   SKU	Select Standard.
   TCP idle timeout (minutes)	Leave the default of 4.

8. Select Next.

9. In the Outbound IP tab, select + Add public IP addresses or prefixes.

10. In Add public IP addresses or prefixes, select Public IP addresses. Select the public IP address you created earlier, public-ip-nat.

11. Select Next.

12. In the Networking tab, in Virtual network, select vnet-1.

13. Leave the checkbox for Default to all subnets unchecked.

14. In Select specific subnets, select subnet-1.

15. Select Review + create, then select Create.

Create load balancer

In this section, you create an internal load balancer that load balances virtual machines. An internal load balancer is used to load balance traffic inside a virtual network with a private IP address.

During the creation of the load balancer, you configure:

• Frontend IP address
• Backend pool
• Inbound load-balancing rules

1. In the search box at the top of the portal, enter Load balancer. Select Load balancers in the search results.

2. In the Load balancer page, select Create.

3. In the Basics tab of the Create load balancer page, enter, or select the following information:

   Setting	Value
   Project details
   Subscription	Select your subscription.
   Resource group	Select test-rg.
   Instance details
   Name	Enter load-balancer
   Region	Select (US) East US 2.
   SKU	Leave the default Standard.
   Type	Select Internal.
   Tier	Leave the default Regional.

4. Select Next: Frontend IP configuration at the bottom of the page.

5. In Frontend IP configuration, select + Add a frontend IP configuration.

6. Enter frontend in Name.

7. Select subnet-1 (10.0.0.0/24) in Subnet.

8. Leave the rest of the options at the default values.

9. Select Add.

10. Select Next: Backend pools at the bottom of the page.

11. In the Backend pools tab, select + Add a backend pool.

12. Enter backend-pool for Name in Add backend pool.

13. Select NIC or IP Address for Backend Pool Configuration.

14. Select Save.

15. Select the Next: Inbound rules button at the bottom of the page.

16. In Load balancing rule in the Inbound rules tab, select + Add a load balancing rule.

17. In Add load balancing rule, enter or select the following information:

    Setting	Value
    Name	Enter http-rule
    IP Version	Select IPv4.
    Frontend IP address	Select front-end.
    Backend pool	Select backend-pool.
    Protocol	Select TCP.
    Port	Enter 80.
    Backend port	Enter 80.
    Health probe	Select Create new. In Name, enter health-probe. Select TCP in Protocol. Leave the rest of the defaults, and select OK.
    Session persistence	Select None.
    Idle timeout (minutes)	Enter or select 15.
    TCP reset	Select Enabled.
    Floating IP	Select Disabled.

18. Select Save.

19. Select the blue Review + create button at the bottom of the page.

20. Select Create.

Create virtual machines

In this section, you create two VMs (vm-1 and vm-2) in two different zones (Zone 1 and Zone 2).

These VMs are added to the backend pool of the load balancer that was created earlier.

1. In the search box at the top of the portal, enter Virtual machine. Select Virtual machines in the search results.

2. Select + Create then Azure virtual machine.

3. In Create a virtual machine, type or select the values in the Basics tab:

   Setting	Value
   Project details
   Subscription	Select your subscription.
   Resource group	Select test-rg.
   Instance details
   Virtual machine name	Enter vm-1.
   Region	Select East US 2.
   Availability options	Select Zone 1.
   Security type	Select Standard.
   Image	Select Ubuntu Server 22.04 LTS - x64 Gen2.
   VM architecture	Leave the default of x64.
   Size	Select a size.
   Administrator account
   Authentication type	Select Password.
   Username	Enter azureuser.
   Password	Enter a password.
   Confirm password	Reenter the password.
   Inbound port rules
   Public inbound ports	Select None.

4. Select the Networking tab, or select Next: Disks, then Next: Networking.

5. In the Networking tab, enter or select the following information:

   Setting	Value
   Network interface
   Virtual network	Select vnet-1.
   Subnet	Select subnet-1 (10.0.0.0/24)
   Public IP	Select None.
   NIC network security group	Select Advanced
   Configure network security group	Select Create new. In the Create network security group, enter nsg-1 in Name. Under Inbound rules, select +Add an inbound rule. In Service, select HTTP. Select Add Select OK
   Load balancing
   Place this virtual machine behind an existing load-balancing solution?	Select the check box.
   Load balancing settings
   Load-balancing options	Select Azure load balancer
   Select a load balancer	Select load-balancer
   Select a backend pool	Select backend-pool

6. Select Review + create.

7. Review the settings, and then select Create.

8. Follow the previous steps to create a VM with the following values and all the other settings the same as vm-1:

   Setting	VM 2
   Name	vm-2
   Availability zone	2
   Network security group	Select the existing nsg-1
   Load-balancing options	Select Azure load balancer
   Select a load balancer	Select load-balancer
   Select a backend pool	Select backend-pool

Test NAT gateway

In this section, you test the NAT gateway. You first discover the public IP of the NAT gateway. You then connect to the test virtual machine and verify the outbound connection through the NAT gateway.

1. In the search box at the top of the portal, enter Public IP. Select Public IP addresses in the search results.

2. Select public-ip-nat.

3. Make note of the public IP address.

   

4. In the search box at the top of the portal, enter Virtual machine. Select Virtual machines in the search results.

5. Select vm-1.

6. On the Overview page, select Connect, then select the Bastion tab.

7. Select Use Bastion.

8. Enter the username and password entered during virtual machine creation. Select Connect.

9. In the bash prompt, enter the following command.

   curl ifconfig.me
   

10. Verify the IP address returned by the command matches the public IP address of the NAT gateway.

    azureuser@vm-1:~$ curl ifconfig.me
    203.0.113.0.25
    

11. Close the bastion connection to vm-1.

When you finish using the resources that you created, you can delete the resource group and all its resources.

1. In the Azure portal, search for and select Resource groups.

2. On the Resource groups page, select the test-rg resource group.

3. On the test-rg page, select Delete resource group.

4. Enter test-rg in Enter resource group name to confirm deletion, and then select Delete.

Next steps

For more information on Azure NAT Gateway, see: