Description

Ensure an Events Service rule in the root compartment watches for network gateway changes and has an action that sends a notification to a monitored topic. The rule should match all of the related event types, so the security team is alerted as soon as these changes happen.

Rationale

Gateways decide how traffic enters and leaves the VCN. Adding an internet gateway or changing a DRG can expose private networks or create new routes to on-premises systems. Alerting on gateway changes gives quick visibility into changes that could open or redirect network access.

Impact

  • The security team is alerted when an internet, NAT, service, local peering, or dynamic routing gateway is changed

  • Speeds up detection of unauthorized or accidental changes

  • Alert volume depends on how often these changes happen

Default Value

By default, no event rules or notification topics are configured.

Pre-Requisites

  • Permission to manage cloudevents-rules and ons-topics in the root compartment

  • A notification topic with at least one confirmed subscription (for example, the security team's email address)

Test Plan

  1. Sign in to the OCI Console at https://cloud.oracle.com.

  2. Open the navigation menu, select Observability & Management, and under Events Service select Rules. In the Compartment filter, select the root compartment (tenancy).

  3. Look for an enabled rule whose conditions match the Networking service and these event types: the Create, Delete, Update, and Change Compartment events for DRG, DRG Attachment, Internet Gateway, Local Peering Gateway, NAT Gateway, and Service Gateway (plus Service Gateway – Attach Service and Detach Service).

  4. Open the rule and verify that its Actions include a Notifications action pointing to a topic with an active subscription.

  5. If no such rule exists, or it has no notification action, follow the implementation steps.

Implementation Steps

  1. Sign in to the OCI Console at https://cloud.oracle.com.

  2. If you do not have a topic, open Developer Services > Application Integration > Notifications, select Create topic, then create a subscription (for example, Email) and confirm it.

  3. Open the navigation menu, select Observability & Management, and under Events Service select Rules. In the Compartment filter, select the root compartment (tenancy).

  4. Select Create rule and enter a name, for example notify-on-network-gateway-changes.

  5. Under Rule conditions, choose Event type, select Service name Networking, and select the event types: the Create, Delete, Update, and Change Compartment events for DRG, DRG Attachment, Internet Gateway, Local Peering Gateway, NAT Gateway, and Service Gateway (plus Service Gateway – Attach Service and Detach Service).

  6. Under Actions, choose Action type Notifications, and select the compartment and topic.

  7. Select Create rule.

Backout Plan

  1. Sign in to the OCI Console at https://cloud.oracle.com.

  2. Open the navigation menu, select Observability & Management, and under Events Service select Rules. In the Compartment filter, select the root compartment (tenancy).

  3. Select the rule and select Disable, or delete the rule.

Reference