Google CloudOverview
Compute Engine instance cannot forward a packet unless the source IP address of the packet matches the IP address of the instance. Similarly, GCP won't deliver a packet whose destination IP address is different than the IP address of the instance receiving the packet. However, both capabilities are required if you want to use instances to help route packets.
Forwarding of data packets should be disabled to prevent data loss or information disclosure.
Rationale
Compute Engine instance cannot forward a packet unless the source IP address of the packet matches the IP address of the instance. Similarly, GCP won't deliver a packet whose destination IP address is different than the IP address of the instance receiving the packet. However, both capabilities are required if you want to use instances to help route packets. To enable this source and destination IP check, disable the canIpForward field, which allows an instance to send and receive packets with non-matching destination or source IPs.
Remediation guidance
Using Console
- Go to the
Compute Engine - Go to
VM Instances - Select the
VM Instance. - Click
Deletebutton.
**Via CLI gcloud **
gcloud compute instances delete ``
As you can only set the canIpForward field at instance creation time. After an instance is created, the field becomes read-only. Therefore delete the VM instance where canIpForward is set to true.
And create a new VM Instance with IP forwarding is set to Off
- Go to
Compute Engine - Click the
Create instancebutton. - Click Management, disk, networking, SSH keys.
- Click
Networking. - Click on the specific
Network interfaces - Ensure
IP forwardingis set tooff. - Specify any other instance parameters you desire.
- Click Create.
Impact
Deleting instance(s) acting as routers/packet forwarders may break the network connectivity.
References
- https://cloud.google.com/compute/docs/networking#canipforward
Notes
You can only set the canIpForward field at instance creation time. After an instance is created, the field becomes read-only.
Multiple Remediation Paths
Google Cloud
SERVICE-WIDE (RECOMMENDED when many resources are affected): Enforce Organization Policies at org/folder level so new resources inherit secure defaults.
gcloud org-policies set-policy policy.yaml
ASSET-LEVEL: Use the product-specific remediation steps above for only the impacted project/resources.
PREVENTIVE: Use org policy constraints/custom constraints and enforce checks in deployment pipelines.
References for Service-Wide Patterns
- GCP Organization Policy overview: https://cloud.google.com/resource-manager/docs/organization-policy/overview
- GCP Organization policy constraints catalog: https://cloud.google.com/resource-manager/docs/organization-policy/org-policy-constraints
- gcloud org-policies: https://cloud.google.com/sdk/gcloud/reference/org-policies
Operational Rollout Workflow
Use this sequence to reduce risk and avoid repeated drift.
1. Contain at Service-Wide Scope First (Recommended)
- Google Cloud: apply organization policy constraints at org/folder scope.
gcloud org-policies set-policy policy.yaml
2. Remediate Existing Affected Assets
- Execute the control-specific Console/CLI steps documented above for each flagged resource.
- Prioritize internet-exposed and production assets first.
3. Validate and Prevent Recurrence
- Re-scan after each remediation batch.
- Track exceptions with owner and expiry date.
- Add preventive checks in IaC/CI pipelines.
Query logic
These are the stored checks tied to this control.
IP forwarding is not enabled on Instances
Connectors
Covered asset types
Expected check: eq []
vms(where:{canIPForward:true}){...AssetFragment}
