Logging metric filter and alert for network changes should be configured


Network traffic flow can be impacted when a network is created, modified, or deleted, or when a network peering connection is created or deleted. Such changes can also indicate suspicious activity. Monitoring changes to VPCs can help detect anomalous actions and ensure traffic flow is not impacted.

Remediation Steps

Google Cloud Console

This is a two-part process. First, you create the log metric. Next, you create an alert policy.

Step 1: To create the log metric:

  • Navigate to Logs-based Metrics and click CREATE METRIC.

  • Ensure Metric Type is set to Counter.

  • Under Details, enter a name and description, and set Units to 1.

  • Under Filter selection, clear any text in the Build filter box and enter the following:

AND (protoPayload.methodName:compute.networks.insert
OR protoPayload.methodName:compute.networks.patch
OR protoPayload.methodName:compute.networks.delete
OR protoPayload.methodName:compute.networks.removePeering
OR protoPayload.methodName:compute.networks.addPeering)
  • Click Create Metric.

Step 2: To create the alert policy:

  • Navigate to Logs-based Metrics and identify the newly created metric under the section User-defined Metrics.

  • Click the 3-dot icon in the rightmost column for the new metric and select Create alert from Metric.

  • In the Find resource type and metric section, remove the selected resource type and select Global as the resource type instead.

  • Set Aggregator to Count and set the desired time period.

  • Under Configuration, choose the alerting threshold and configuration that makes sense for your organization. For example, a threshold of zero (0) for the most recent value ensures that a notification is triggered for every owner change in the project:

Set `Configuration`:
- Condition: above
- Threshold: 0
- For: most recent value
  • Click Save.

  • Configure the desired notifications channels in the section Notifications.

  • Name the policy and click Save.

gcloud CLI

  • To create the log metric:

    • gcloud beta logging metrics create

For flags, see Google Cloud’s CLI reference.

  • To create the alert policy:

    • gcloud alpha monitoring policies create

For flags, see Google Cloud’s CLI reference.