This image shows the north-south inbound traffic flows from an on-premises VM to a VM in a Secure Private subnet via Network Firewall. It includes one Secure VCN but similarly you can have multiple secured VCNs.
Secured VCN-A (10.10.0.0/16) includes the following components:
- Firewall Subnet (10.10.1.0/24) which includes a Network Firewall and associated IP address to it. Ensure that Firewall Subnet is in a private subnet since we are protecting private subnet workloads.
- Secured Private Subnet (10.10.0.0/24) which includes application workloads. We have a VM available in this subnet with 10.10.0.10 private IP address.
- Dynamic Routing Gateway to support on-premises connectivity to Secured VCN via FastConnect and/or VPN. DRG has an attachment to Secured VCN and associated VCN Ingress Route Table attached to that attachment.
- Route tables are associated to Firewall Subnet, Secured Private Subnet and internet gateway ensuring that the traffic is routed via Network Firewall.
North-south traffic flow from the on-premises VM to Virtual Machine in
Secured Private Subnet:
- Traffic that moves from the on-premises destination (172.16.10.10) to workload VM (10.10.0.10) is routed through Dynamic Routing Gateway (destination 10.10.0.0/24).
- Traffic from DRG Secured VCN attachment and through VCN Ingress Route Table goes to IP Address of Network Firewall based on the destination (10.10.0.10).
- Firewall inspects and protects the traffic as per firewall policy. Once inspected and protected, traffic exits from Firewall IP address through Firewall Subnet Route Table (destination 10.10.0.0/24).
- Firewall Subnet route table sends the required destination.
- Return traffic comes from Secured Private VM to Network Firewall and will follow the same path since we have symmetric routing in place on each route table.