Detections
Analytics

3.2 Ensure Legacy Networks Do Not Exist for Older Projects

Information

In order to prevent use of legacy networks, a project should not have a legacy network configured. As of now, Legacy Networks are gradually being phased out, and you can no longer create projects with them. This recommendation is to check older projects to ensure that they are not using Legacy Networks.

Legacy networks have a single network IPv4 prefix range and a single gateway IP address for the whole network. The network is global in scope and spans all cloud regions. Subnetworks cannot be created in a legacy network and are unable to switch from legacy to auto or custom subnet networks. Legacy networks can have an impact for high network traffic projects and are subject to a single point of contention or failure.

Solution

From Google Cloud CLI

1.Create a new non-legacy network

gcloud compute networks create <NEW_NETWORK_NAME> --subnet-mode=custom --project=<PROJECT_ID>

2.Create required subnets (for custom mode networks)

gcloud compute networks subnets create <SUBNET_NAME> \\
 --network=<NEW_NETWORK_NAME> \\
 --region=<REGION> \\
 --range=<IP_CIDR_RANGE> \\
 --project=<PROJECT_ID>

3.Migrate existing resources

 - Compute Engine VMs: Create new VMs in the new network or use the gcloud compute instances move command (if supported)
 - Firewall rules: Recreate required firewall rules
 - Routes: Recreate any custom routes
 - Cloud VPN / Cloud Interconnect: Reconfigure to use the new network

4.Verify no resources remain in the legacy network

gcloud compute instances list --filter="network=<LEGACY_NETWORK_NAME>" --project=<PROJECT_ID>

 - Delete the legacy network

gcloud compute networks delete <LEGACY_NETWORK_NAME> --project=<PROJECT_ID>

Impact:

None.

See Also

https://workbench.cisecurity.org/benchmarks/22181

Item Details

Category: ACCESS CONTROL, CONFIGURATION MANAGEMENT

References: 800-53|AC-18, 800-53|AC-18(1), 800-53|AC-18(3), 800-53|CM-2, 800-53|CM-6, 800-53|CM-7, 800-53|CM-7(1), 800-53|CM-9, CSCv7|11.1

Plugin: GCP

Control ID: d8a8323336d934a918ed64627422237591ae370978443a48d4d01c3b8bf51fec