Your company is deploying a web application on Google Kubernetes Engine (GKE) with an Internal Load Balancer (ILB) as the ingress. The application must only be accessible from within the same VPC and from an on-premises network connected via Cloud VPN. The on-premises network uses IP range 10.0.0.0/8. You have already created the ILB with a backend service. What is the most secure way to restrict access to the ILB?