This tutorial shows how to use the Network Connectivity Center star topology with Palo Alto Networks VM-Series firewalls. This solution supports the following use-cases:

• Secure internet inbound and outbound traffic to edge VPC networks.
• Secure east-west traffic between edge VPC networks.
• Secure Cloud VPN traffic to edge VPC networks.

This tutorial is intended for network administrators, solution architects, and security professionals who are familiar with Compute Engine and Virtual Private Cloud (VPC) networking.

The star topology uses two spoke groups with separate route tables to enforce segmentation. All networks belonging to a spoke group are connected to an NCC hub.

• Center group: Allows traffic between center spokes and between center and edge spokes.
• Edge group: Allows traffic only to center spokes; direct edge-to-edge communication is blocked.

The VM-Series trust-vpc belongs to the center group, while the protected networks, spoke1-vpc and spoke2-vpc belong to the edge group. All ingress and egress traffic from edge networks is routed through the center group, where it is inspected by the VM-Series firewall.

For more information please see Network Connectivity Center Star Topology.

The following is required for this tutorial:

1. A Google Cloud project.
2. A machine with Terraform version:>= 1.6.0

1. Enable the required APIs and clone the repository.

   gcloud services enable compute.googleapis.com
   git clone https://github.com/PaloAltoNetworks/google-cloud-ncc-tutorial
   cd google-cloud-ncc-tutorial
   

2. Generate an SSH key.

   ssh-keygen -f ~/.ssh/vmseries-tutorial -t rsa
   

3. Create a terraform.tfvars file.

   cp terraform.tfvars.example terraform.tfvars
   

4. Edit the terraform.tfvars file and set values for the following variables:

   Key	Value
   project_id	The Project ID within Google Cloud.
   public_key_path	The local path of the public key you previously created
   vmseries_mgmt_ips	A list of IPv4 addresses which require access to the VM-Series MGT NIC.
   vmseries_image	The VM-Series image to deploy.
   configure_ncc	If true, create the NCC hub, center, and edge groups.

gcloud compute images list --project paloaltonetworksgcp-public --filter='name ~ .*vmseries-flex.*'

When no further changes are necessary in the configuration, deploy the resources.

1. Initialize and apply the Terraform plan.

   terraform init
   terraform apply
   

   Enter yes to create the resources.

2. After all the resources are created, Terraform displays the following message:

    Apply complete!
   
    Outputs:
   
    EXTERNAL_LB_IP = "35.192.118.173"

1. In Cloud Shell, create an environment variable to represent your Project ID.

    export PROJECT_ID=YOUR_PROJECT_ID

2. Retrieve the name of your NCC hub.

   export HUB_NAME=$(gcloud network-connectivity hubs list \
       --project=$PROJECT_ID \
       --format="value(name)")
   

3. list the spokes and verify that spoke1-vpc, spoke2-vpc, and the trust-vpc are onboarded to the NCC hub.

   gcloud network-connectivity hubs list-spokes $HUB_NAME \
       --project=$PROJECT_ID \
       --format='table(name,group,spokeType,state)'
   

   (output)

    NAME    GROUP   TYPE         STATE
    spoke1  edge    VPC_NETWORK  ACTIVE
    spoke2  edge    VPC_NETWORK  ACTIVE
    trust   center  VPC_NETWORK  ACTIVE

To access the VM-Series's user interface, a password must be set for the admin user.

1. Retrieve the EXTERNAL_IP attached to the VM-Series MGT interface (NIC1).

   gcloud compute instances list \
       --filter='tags.items=(vmseries-tutorial)' \
       --format='value(EXTERNAL_IP)'
   

2. SSH to the VM-Series using the EXTERNAL_IP with your private SSH key.

    ssh admin@EXTERNAL_IP -i ~/.ssh/vmseries-tutorial

3. On the VM-Series, set a password for the admin username.

   configure
   set mgt-config users admin password
   

4. Commit the changes.

   commit
   

5. Enter exit twice to terminate the session.

6. Access the VM-Series web interface using a web browser. Login with the admin user and password.

    https://EXTERNAL_IP

Test inbound internet traffic by accessing the forwarding rule on the external load balancer. Traffic received by the load balancer is forwarded to the VM-Seriess for inspection. If the VM-Series permits the traffic, it performs source NAT to its trust interface (for synchronous response) and destination NAT to the target application in the spoke VPC network.

1. Open a HTTP connection to the web service on spoke1-vm1 by copying the EXTERNAL_LB_IP output value into a web browser.

   You can retrieve the EXTERNAL_LB_IP by entering terraform output in Cloud Shell.

    http://EXTERNAL_LB_IP

   

2. Open an SSH session with spoke2-vm1 using the EXTERNAL_LB_IP output value.

    ssh paloalto@EXTERNAL_LB_IP -i ~/.ssh/vmseries-tutorial

3. On the VM-Series, go to Monitor → Traffic.

4. Enter the following into the log filter to view your internet inbound traffic.

   (( port.dst eq '80' ) or ( port.dst eq '22' )) and (( app eq 'ssh' ) or ( app eq 'web-browsing' ))
   

   

![NOTE] The external load balancer distributes the HTTP & SSH request to the VM-Series. The VM-Series inspects and translates HTTP traffic to spoke1-vm1 and SSH traffic to spoke2-vm1.

In an NCC star topology, protected workloads reside in edge VPCs, and the VM-Series is deployed in the center VPC, which serves as its trust-vpc. The NCC hub shares routes with the edge spokes so they forward all traffic to the center for inspection, using the VM-Series internal load balancer as the next hop.

2. From spoke2-vm1, test outbound internet inspection by generating pseudo malicious traffic to the internet.

   curl -s -o /dev/null -w "%{http_code}\n" http://www.eicar.org/cgi-bin/.%2e/.%2e/.%2e/.%2e/bin/sh --data "echo Content-Type: text/plain; echo; uname -a" --max-time 2
   curl -s -o /dev/null -w "%{http_code}\n" http://www.eicar.org/cgi-bin/user.sh -H "FakeHeader:() { :; }; echo Content-Type: text/html; echo ; /bin/uname -a" --max-time 2
   

3. Test east-west inspection by generating pseudo malicious traffic between spoke2-vm1 and spoke1-vm1.

   curl http://10.1.0.10/cgi-bin/../../../..//bin/cat%20/etc/passwd
   

4. On the VM-Series, go to Monitor → Threat to view the threat logs.

   

Delete all the resources when you no longer need them.

1. Run the following command

   terraform destroy
   

2. At the prompt to perform the actions, enter yes.

   After all the resources are deleted, Terraform displays the following message:

   Destroy complete!
   

• Learn about the VM-Series on Google Cloud.
• Getting started with Palo Alto Networks PAN-OS.
• Read about securing Google Cloud Networks with the VM-Series.
• Learn about VM-Series licensing on all platforms.
• Use the VM-Series Terraform modules for Google Cloud.