GSP459

Overview

Google Cloud’s Network Address Translation (NAT) service enables you to provision your application instances without public IP addresses while also allowing them to access the internet for updates, patching, config management, and more in a controlled and efficient manner.

In this lab, you will configure Private Google Access and Cloud NAT for a VM instance that doesn't have an external IP address. Then, you will verify access to public IP addresses of Google APIs and services and other connections to the internet. Finally, you will use Cloud NAT logging to record connections made in your gateway.

What you'll learn

In this lab, you will learn how to perform the following tasks:

• Configure a VM instance that doesn't have an external IP address.
• Create a bastion host to connect to the VM that doesn't have an external IP address.
• Enable Private Google Access on a subnet.
• Configure a Cloud NAT gateway.
• Verify access to public IP addresses of Google APIs and services and other connections to the internet.
• Log NAT connections with Cloud NAT logging.

Setup and requirements

Before you click the Start Lab button

Read these instructions. Labs are timed and you cannot pause them. The timer, which starts when you click Start Lab, shows how long Google Cloud resources will be made available to you.

This hands-on lab lets you do the lab activities yourself in a real cloud environment, not in a simulation or demo environment. It does so by giving you new, temporary credentials that you use to sign in and access Google Cloud for the duration of the lab.

To complete this lab, you need:

• Access to a standard internet browser (Chrome browser recommended).

Note: Use an Incognito or private browser window to run this lab. This prevents any conflicts between your personal account and the Student account, which may cause extra charges incurred to your personal account.

• Time to complete the lab---remember, once you start, you cannot pause a lab.

Note: If you already have your own personal Google Cloud account or project, do not use it for this lab to avoid extra charges to your account.

How to start your lab and sign in to the Google Cloud console

1. Click the Start Lab button. If you need to pay for the lab, a pop-up opens for you to select your payment method. On the left is the Lab Details panel with the following:

   • The Open Google Cloud console button
   • Time remaining
   • The temporary credentials that you must use for this lab
   • Other information, if needed, to step through this lab

2. Click Open Google Cloud console (or right-click and select Open Link in Incognito Window if you are running the Chrome browser).

   The lab spins up resources, and then opens another tab that shows the Sign in page.

   Tip: Arrange the tabs in separate windows, side-by-side.

   Note: If you see the Choose an account dialog, click Use Another Account.

3. If necessary, copy the Username below and paste it into the Sign in dialog.

   {{{user_0.username | "Username"}}}

   You can also find the Username in the Lab Details panel.

4. Click Next.

5. Copy the Password below and paste it into the Welcome dialog.

   {{{user_0.password | "Password"}}}

   You can also find the Password in the Lab Details panel.

6. Click Next.

   Important: You must use the credentials the lab provides you. Do not use your Google Cloud account credentials. Note: Using your own Google Cloud account for this lab may incur extra charges.

7. Click through the subsequent pages:

   • Accept the terms and conditions.
   • Do not add recovery options or two-factor authentication (because this is a temporary account).
   • Do not sign up for free trials.

After a few moments, the Google Cloud console opens in this tab.

Note: To view a menu with a list of Google Cloud products and services, click the Navigation menu at the top-left.

Activate Cloud Shell

Cloud Shell is a virtual machine that is loaded with development tools. It offers a persistent 5GB home directory and runs on the Google Cloud. Cloud Shell provides command-line access to your Google Cloud resources.

1. Click Activate Cloud Shell at the top of the Google Cloud console.

When you are connected, you are already authenticated, and the project is set to your Project_ID, . The output contains a line that declares the Project_ID for this session:

Your Cloud Platform project in this session is set to {{{project_0.project_id | "PROJECT_ID"}}}

gcloud is the command-line tool for Google Cloud. It comes pre-installed on Cloud Shell and supports tab-completion.

2. (Optional) You can list the active account name with this command:

gcloud auth list

3. Click Authorize.

Output:

ACTIVE: * ACCOUNT: {{{user_0.username | "ACCOUNT"}}} To set the active account, run: $ gcloud config set account `ACCOUNT`

4. (Optional) You can list the project ID with this command:

gcloud config list project

Output:

[core] project = {{{project_0.project_id | "PROJECT_ID"}}} Note: For full documentation of gcloud, in Google Cloud, refer to the gcloud CLI overview guide.

Task 1. Create the VM instances

You will now create one VM instance that has no external IP address and another VM instance to serve as a bastion host.

Create a VPC network and firewall rules

First, create a VPC network for the VM instances and a firewall rule to allow SSH access.

1. In the Cloud Console, on the Navigation menu (), click VPC network > VPC networks.

2. Click Create VPC Network.

3. For Name, type privatenet.

4. For Subnet creation mode, click Custom.

5. Specify the following, and leave the remaining settings as their defaults:

   Property	Value (type value or select option as specified)
   Name	privatenet-us
   Region
   IP address range	10.130.0.0/20

Note: Don't enable Private Google access yet!

6. Click Done.

7. Click Create and wait for the network to be created.

8. In the left pane, click Firewall.

9. Click Create Firewall Rule.

10. Specify the following, and leave the remaining settings as their defaults:

    Property	Value (type value or select option as specified)
    Name	privatenet-allow-ssh
    Network	privatenet
    Targets	All instances in the network
    Source filter	IPv4 ranges
    Source IPv4 ranges	0.0.0.0/0
    Protocols and ports	Specified protocols and ports

11. For tcp, specify port 22.

12. Click Create.

Click Check my progress to verify the objective. Create a VPC network and firewall rules

Create the VM instance with no public IP address

1. In the Cloud Console, on the Navigation menu (), click Compute Engine > VM instances.

2. Click Create Instance.

3. Specify the following, and leave the remaining settings as their defaults:

   Property	Value (type value or select option as specified)
   Name	vm-internal
   Region
   Zone
   Machine type	e2-medium(2 vCPU, 1 core, 4 GB memory)

4. Click Advanced Options.

5. Click Networking.

6. For Network interfaces.

7. Specify the following, and leave the remaining settings as their defaults:

   Property	Value (type value or select option as specified)
   Network	privatenet
   Subnetwork	privatenet-us
   External IPv4 address	None

Note: The default setting for a VM instance is to have an ephemeral external IP address. This behavior can be changed with a policy constraint at the organization or project level. To learn more about controlling external IP address on VM instances, refer to the Restricting external IP addresses to specific VMs.

8. Click Done.
9. Click Create, and wait for the VM instance to be created.
10. On the VM instances page, verify that the External IP of vm-internal is None.

Click Check my progress to verify the objective. Create the VM instance with no public IP address

Create the bastion host

Because vm-internal has no external IP address, it can only be reached by other instances on the network or via a managed VPN gateway. This includes SSH access to vm-internal, which is grayed out (unavailable) in the Cloud Console.

In order to connect via SSH to vm-internal, create a bastion host vm-bastion on the same VPC network as vm-internal.

1. In the Cloud Console, on the VM instances page, click Create Instance.

2. Specify the following, and leave the remaining settings as their defaults:

   Property	Value (type value or select option as specified)
   Name	vm-bastion
   Region
   Zone
   Machine type	e2-micro (2vCPU)
   Identity and API access > Access scopes	Set access for each API
   Compute Engine	Read Write

3. Click Advanced Options..

4. Click Networking.

5. For Network interfaces.

6. Specify the following, and leave the remaining settings as their defaults:

   Property	Value (type value or select option as specified)
   Network	privatenet
   Subnetwork	privatenet-us
   External IPv4 address	Ephemeral

7. Click Done.

8. Click Create, and wait for the VM instance to be created.

Note: By creating vm-bastion in the same VPC network as vm-internal, you will be able to access vm-internal through its internal IP address or host name.

Click Check my progress to verify the objective. Create the Bastion host

SSH to vm-bastion and verify access to vm-internal

Verify that you can access vm-internal through vm-bastion.

1. For vm-bastion, click SSH to launch a terminal and connect.

2. From the vm-bastion SSH terminal, verify external connectivity by running the following command:

ping -c 2 www.google.com

This should work!

3. Connect to vm-internal by running the following command:

gcloud compute ssh vm-internal --zone={{{project_0.default_zone | Zone}}} --internal-ip

4. When asked if you want to continue, enter Y.
5. When prompted for a passphrase, press ENTER for no passphrase, then ENTER again.

6. Test the external connectivity of vm-internal by running the following command:

ping -c 2 www.google.com

This should not work because vm-internal has no external IP address!

7. Wait for the ping command to complete.
8. Close the connection to vm-internal by running the following command:

exit

9. Close the SSH terminal of vm-bastion by running the following command:

exit Note: When instances do not have external IP addresses, they can only be reached by other instances on the network or via a managed VPN gateway. In this case, vm-bastion serves as a management and maintenance interface to vm-internal.

Task 2. Enable private Google access

VM instances that have no external IP addresses can use Private Google Access to reach external IP addresses of Google APIs and services. By default, Private Google Access is disabled on a VPC network.

Create a Cloud Storage bucket

Create a Cloud Storage bucket to test access to Google APIs and services.

1. In the Cloud Console, on the Navigation menu (), click Cloud Storage > Bucket.

2. Click Create.

3. Specify the following, and leave the remaining settings as their defaults:

   Property	Value (type value or select option as specified)
   Name	Enter a globally unique name
   Default storage class	Multi-Regional

4. Click Create.

5. Note the name of your storage bucket for the next subtask. It will be referred to as [my_bucket].

Copy an image file into your bucket

Copy an image from a public Cloud Storage bucket to your own bucket.

1. Run the following command in Cloud Shell, replacing [my_bucket] with your bucket's name:

gsutil cp gs://cloud-training/gcpnet/private/access.png gs://[my_bucket]

2. In the Cloud Console, click Refresh Bucket to verify that the image was copied.

You can click on the name of the image in the Cloud Console to view an example of how Private Google Access is implemented.

Access the image from your VM instances

1. In the Cloud Console, on the Navigation menu (), click Compute Engine > VM instances.

2. For vm-bastion, click SSH to launch a terminal and connect.
3. Try to copy the image to vm-bastion by running the following command, replacing [my_bucket] with your bucket's name:

gsutil cp gs://[my_bucket]/*.png .

This should work because vm-bastion has an external IP address!

4. Connect to vm-internal by running the following command:

gcloud compute ssh vm-internal --zone={{{project_0.default_zone | Zone}}} --internal-ip

5. If prompted, type Y to continue.
6. Try to copy the image to vm-internal by running the following command, replacing [my_bucket] with your bucket's name:

gsutil cp gs://[my_bucket]/*.png . Note: This should not work: vm-internal can only send traffic within the VPC network because Private Google Access is disabled (by default).

7. To terminate the request after the first attempt, press CTRL+C.

8. Close the SSH terminal.

Enable private Google access

Private Google access is enabled at the subnet level. When it is enabled, instances in the subnet that only have private IP addresses can send traffic to Google APIs and services through the default route (0.0.0.0/0) with a next hop to the default internet gateway.

1. In the Cloud Console, on the Navigation menu (), click VPC network > VPC networks.
2. Click privatenet > privatenet-us to open the subnet.
3. Click Edit.
4. For Private Google access, select On.
5. Click Save.

Note: Yes, enabling Private Google Access is as simple as selecting On for Private Google access within the subnet!

6. In the Cloud Console, on the Navigation menu (), click Compute Engine > VM instances.
7. For vm-bastion, click SSH to launch a terminal and connect.
8. Connect to vm-internal by running the following command:

gcloud compute ssh vm-internal --zone={{{project_0.default_zone | Zone}}} --internal-ip

9. If prompted, type Y to continue.
10. Try to copy the image to vm-internal by running the following command:

gsutil cp gs://[my_bucket]/*.png .

This should work as vm-internal's subnet has Private Google Access enabled!

11. Close the SSH terminal.

Note: To view the eligible APIs and services that you can use with Private Google Access, see supported services in the Private Google Access overview.

Click Check my progress to verify the objective. Create a Cloud Storage Bucket and Enable Private Google Access

Task 3. Configure a Cloud NAT gateway

Although vm-internal can now access certain Google APIs and services without an external IP address, the instance cannot access the internet for updates and patches. You will now configure a Cloud NAT gateway, which allows vm-internal to reach the internet.

Try to update the VM instances

1. For vm-bastion, click SSH to launch a terminal and connect.
2. Try to re-synchronize the package index of vm-bastion by running the following:

sudo apt-get update

The output should look like this:

... Reading package lists... Done

This should work because vm-bastion has an external IP address!

3. Connect to vm-internal by running the following command:

gcloud compute ssh vm-internal --zone={{{project_0.default_zone | Zone}}} --internal-ip

4. If prompted, type Y to continue.
5. Try to re-synchronize the package index of vm-internal by running the following:

sudo apt-get update

This should only work for Google Cloud packages because vm-internal only has access to Google APIs and services!

6. Press CTRL+C to stop the request.
7. Close the SSH terminal.

Configure a Cloud NAT gateway

Cloud NAT is a regional resource. You can configure it to allow traffic from all ranges of all subnets in a region, from specific subnets in the region only, or from specific primary and secondary CIDR ranges only.

1. In the Cloud Console, on the Navigation menu (), click Network services > Cloud NAT.

2. Click Get started to configure a NAT gateway.

3. Specify the following:

   Property	Value (type value or select option as specified)
   Gateway name	nat-config
   Network	privatenet
   Region

4. For Cloud Router, select Create new router.

5. For Name, type nat-router.

6. Click Create.

Note: The NAT mapping section allows you to choose the subnets to map to the NAT gateway. You can also manually assign static IP addresses that should be used when performing NAT. Do not change the NAT mapping configuration in this lab.

7. Click Create.
8. Wait for the gateway's Status to change to Running.

Verify the Cloud NAT gateway

It may take up to 3 minutes for the NAT configuration to propagate to the VM, so wait at least a minute before trying to access the internet again.

1. In the Cloud Console, on the Navigation menu (), click Compute Engine > VM instances.
2. For vm-bastion, click SSH to launch a terminal and connect.
3. Connect to vm-internal by running the following command:

gcloud compute ssh vm-internal --zone={{{project_0.default_zone | Zone}}} --internal-ip

4. If prompted, type Y to continue.
5. Try to re-synchronize the package index of vm-internal by running the following:

sudo apt-get update

The output should look like this:

... Reading package lists... Done

This should work because vm-internal is using the NAT gateway!

6. Close the SSH terminal.

Note: The Cloud NAT gateway implements outbound NAT, but not inbound NAT. In other words, hosts outside of your VPC network can only respond to connections initiated by your instances; they cannot initiate their own, new connections to your instances via NAT.

Click Check my progress to verify the objective. Configure a Cloud NAT gateway

Task 4. Configure and view logs with Cloud NAT Logging

Cloud NAT logging allows you to log NAT connections and errors. When Cloud NAT logging is enabled, one log entry can be generated for each of the following scenarios:

• When a network connection using NAT is created.
• When a packet is dropped because no port was available for NAT.

You can opt to log both kinds of events, or just one or the other. Created logs are sent to Cloud Logging.

Enabling logging

If logging is enabled, all collected logs are sent to Stackdriver by default. You can filter these so that only certain logs are sent.

You can also specify these values when you create a NAT gateway or by editing one after it has been created. The following directions show how to enable logging for an existing NAT gateway.

1. In the Cloud Console, on the Navigation menu (), click Network services > Cloud NAT.

2. Click on the nat-config gateway and then click Edit.

3. Click Advanced configurations.

4. Under Stackdriver logging, select Translation and errors and then click Save.

NAT logging in Stackdriver

Now that you have set up Cloud NAT logging for the nat-config gateway, let's find out where we can view our logs. You should have left off on the following page with your gateway updated:

1. Click on nat-config to expose its details. Then click on the Logs tab. Then click the link to Logging.

2. This will open a new tab with Statckdriver logging—ensure that the top of your page resembles the following:

You will see that there aren't any logs yet—that's because we just enabled this feature for the gateway. Keep this tab open and return to your other Cloud Console tab.

Generating logs

As a reminder, Cloud NAT logs are generated for the following sequences:

• When a network connection using NAT is created.
• When a packet is dropped because no port was available for NAT.

Let's connect the bastion host to the internal VM again to see if any logs are generated.

1. In the Cloud Console, on the Navigation menu (), click Compute Engine > VM instances.
2. For vm-bastion, click SSH to launch a terminal and connect.
3. Connect to vm-internal by running the following command:

gcloud compute ssh vm-internal --zone={{{project_0.default_zone | Zone}}} --internal-ip

4. If prompted, type Y to continue.
5. Try to re-synchronize the package index of vm-internal by running the following:

sudo apt-get update

The output should look like this:

... Reading package lists... Done

6. Close the SSH terminal.

Let's see if opening up this connection revealed anything new in our logs.

Viewing logs

1. Return to your NAT Logging tab and click the Jump to now button.

2. You should see two new logs that were generated after connecting the bastion host to the internal VM.

As we see, the logs give us details on the VPC network we connected to and the connection method we used. Feel free to expand different labels and details.

Congratulations!

This concludes this self-paced lab, Configuring Private Google Access and Cloud NAT.

You created vm-internal, an instance with no external IP address, and vm-bastion, a bastion host to securely connect to vm-internal. Then you enabled Private Google Access, configured a NAT gateway, and verified that vm-internal can access Google APIs and services and other public IP addresses. Finally, you learned how to configure NAT Logging and how to generate and view those logs in Stackdriver.

VM instances without external IP addresses are isolated from external networks. Using Cloud NAT, these instances can access the internet for updates and patches, and in some cases, for bootstrapping. As a managed service, Cloud NAT provides high availability without user management and intervention.

Next steps / Learn more

• Check out Private Access Options for Services.
• Learn more about NAT gateway at Cloud NAT.
• Check out the lab titled Using a NAT Gateway with Kubernetes Engine.

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Manual Last Updated: March 20, 2024

Lab Last Tested: March 20, 2024

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