Collect Cloud NAT logs

This document describes how you can collect Cloud NAT logs by enabling Google Cloud telemetry ingestion to Google Security Operations and how log fields of Cloud NAT logs map into Google Security Operations Unified Data Model (UDM) fields.

For more information, see Data ingestion to Google Security Operations.

A typical deployment consists of Cloud NAT logs enabled for ingestion to Google Security Operations. Each customer deployment might differ from this representation and might be more complex.

The deployment contains the following components:

• Google Cloud: The Google Cloud services and products from which you collect logs.

• Cloud NAT logs: The Cloud NAT logs that are enabled for ingestion into Google Security Operations.

• Google Security Operations: Google Security Operations retains and analyzes the logs from Cloud NAT.

An ingestion label identifies the parser which normalizes raw log data to structured UDM format. The information into this document applies to the parser with the GCP_CLOUD_NAT ingestion label.

Before you begin

• Ensure that all systems in the deployment architecture are configured in the UTC time zone.

Configure Google Cloud to ingest Cloud NAT logs

For more information on how to ingest logs to Google Security Operations, see Ingest Google Cloud logs to Google Security Operations.

If you encounter issues when you ingest Cloud NAT logs, contact Google Security Operations support.

Field mapping reference

This section explains how the Google Security Operations parser maps Cloud NAT fields to Google Security Operations Unified Data Model (UDM) fields.

Deprecated:

The following labels fields for UDM nouns are deprecated: about.labels, intermediary.labels, observer.labels, principal.labels, src.labels, security_result.about.labels, and target.labels. For existing parsers, in addition to these UDM fields, the logs fields are also mapped to key/value additional.fields UDM fields. For new parsers, the key/value settings in additional.fields UDM fields are used instead of the deprecated labels UDM fields. We recommend that you update the existing rules to use the key/value settings in the additional.fields UDM fields instead of the deprecated labels UDM fields.

Log field	UDM mapping	Logic
	metadata.event_type	The metadata.event_type UDM field is set to NETWORK_CONNECTION.
	metadata.product_name	The metadata.product_name UDM field is set to GCP Cloud NAT.
	metadata.vendor_name	The metadata.vendor_name UDM field is set to Google Cloud Platform.
receiveTimestamp	metadata.collected_timestamp
timestamp	metadata.event_timestamp
logName	security_result.category_details
insertId	metadata.product_log_id
	network.direction	The network.direction UDM field is set to OUTBOUND.
	network.ip_protocol	If the jsonPayload.connection.protocol log field value contains one of the following values, then the network.ip_protocol UDM field is set to ICMP. 1 ICMP ICMPV6 58 1.0 58.0 Else, if the jsonPayload.connection.protocol log field value contains one of the following values, then the network.ip_protocol UDM field is set to IGMP. 2 IGMP 2.0 Else, if the jsonPayload.connection.protocol log field value contains one of the following values, then the network.ip_protocol UDM field is set to TCP. 6 TCP 6.0 Else, if the jsonPayload.connection.protocol log field value contains one of the following values, then the network.ip_protocol UDM field is set to UDP. 17 UDP 17.0 Else, if the jsonPayload.connection.protocol log field value contains one of the following values, then the network.ip_protocol UDM field is set to IP6IN4. 41 IP6IN4 41.0 Else, if the jsonPayload.connection.protocol log field value contains one of the following values, then the network.ip_protocol UDM field is set to GRE. 47 GRE 47.0 Else, if the jsonPayload.connection.protocol log field value contains one of the following values, then the network.ip_protocol UDM field is set to ESP. 50 ESP 50.0 Else, if the jsonPayload.connection.protocol log field value contains one of the following values, then the network.ip_protocol UDM field is set to EIGRP. 88 EIGRP 88.0 Else, if the jsonPayload.connection.protocol log field value contains one of the following values, then the network.ip_protocol UDM field is set to ETHERIP. 97 ETHERIP 97.0 Else, if the jsonPayload.connection.protocol log field value contains one of the following values, then the network.ip_protocol UDM field is set to PIM. 103 PIM 103.0 Else, if the jsonPayload.connection.protocol log field value contains one of the following values, then the network.ip_protocol UDM field is set to VRRP. 112 VRRP 112.0
jsonPayload.connection.src_ip	principal.ip
jsonPayload.connection.src_port	principal.port
jsonPayload.connection.nat_ip	principal.nat_ip
jsonPayload.connection.nat_port	principal.nat_port
jsonPayload.vpc.project_id	intermediary.resource_ancestors.name	If the jsonPayload.vpc.project_id log field value is not empty, then the //cloudresourcemanager.googleapis.com/projects/%{jsonPayload.vpc.project_id} log field is mapped to the intermediary.resource_ancestors.name UDM field.
	intermediary.resource_ancestors.resource_type	If the jsonPayload.vpc.project_id log field value is not empty, then the intermediary.resource_ancestors.resource_type UDM field is set to CLOUD_PROJECT.
	intermediary.resource_ancestors.attribute.cloud.environment	If the jsonPayload.vpc.project_id log field value is not empty, then the intermediary.resource_ancestors.attribute.cloud.environment UDM field is set to GOOGLE_CLOUD_PLATFORM.
jsonPayload.vpc.vpc_name	intermediary.resource_ancestors.name
	intermediary.resource_ancestors.resource_type	If the jsonPayload.vpc.vpc_name log field value is not empty or the jsonPayload.vpc.subnetwork_name log field value is not empty, then the intermediary.resource_ancestors.resource_type UDM field is set to VPC_NETWORK.
	intermediary.resource_ancestors.attribute.cloud.environment	If the jsonPayload.vpc.vpc_name log field value is not empty or the jsonPayload.vpc.subnetwork_name log field value is not empty, then the intermediary.resource_ancestors.attribute.cloud.environment UDM field is set to GOOGLE_CLOUD_PLATFORM.
jsonPayload.vpc.subnetwork_name	intermediary.resource_ancestors.attribute.labels [vpc_subnetwork_name]
jsonPayload.gateway_identifiers.gateway_name	intermediary.resource.name
	intermediary.resource.resource_type	If the jsonPayload.gateway_identifiers.gateway_name log field value is not empty or the resource.type log field value is not empty or the resource.labels.region log field value is not empty or the jsonPayload.gateway_identifiers.router_name log field value is not empty or the resource.labels.router_id log field value is not empty, then the intermediary.resource.resource_type UDM field is set to BACKEND_SERVICE.
resource.type	intermediary.resource.resource_subtype
jsonPayload.gateway_identifiers.region	intermediary.location.name
	intermediary.resource.attribute.cloud.environment	If the jsonPayload.gateway_identifiers.gateway_name log field value is not empty or the resource.type log field value is not empty or the resource.labels.region log field value is not empty or the jsonPayload.gateway_identifiers.router_name log field value is not empty or the resource.labels.router_id log field value is not empty, then the intermediary.resource.attribute.cloud.environment UDM field is set to GOOGLE_CLOUD_PLATFORM.
resource.labels.region	intermediary.resource.attribute.cloud.availability_zone
jsonPayload.gateway_identifiers.router_name	intermediary.resource.attribute.labels [gateway_identifiers_router_name]
resource.labels.router_id	intermediary.resource.attribute.labels [resource_labels_router_id]
jsonPayload.endpoint.project_id	principal.resource_ancestors.name	If the jsonPayload.endpoint.project_id log field value is not empty, then the //cloudresourcemanager.googleapis.com/projects/%{jsonPayload.endpoint.project_id} log field is mapped to the principal.resource_ancestors.name UDM field.
	principal.resource_ancestors.resource_type	If the jsonPayload.endpoint.project_id log field value is not empty, then the principal.resource_ancestors.resource_type UDM field is set to CLOUD_PROJECT.
	principal.resource_ancestors.attribute.cloud.environment	If the jsonPayload.endpoint.project_id log field value is not empty, then the principal.resource_ancestors.attribute.cloud.environment UDM field is set to GOOGLE_CLOUD_PLATFORM.
jsonPayload.endpoint.vm_name	principal.hostname
jsonPayload.endpoint.vm_name	principal.asset.hostname
jsonPayload.endpoint.vm_name	principal.resource.name
	principal.resource.resource_type	If the jsonPayload.endpoint.vm_name log field value is not empty or the jsonPayload.endpoint.zone log field value is not empty, then the principal.resource.resource_type UDM field is set to VIRTUAL_MACHINE.
	principal.resource.attribute.cloud.environment	If the jsonPayload.endpoint.vm_name log field value is not empty or the jsonPayload.endpoint.zone log field value is not empty, then the principal.resource.attribute.cloud.environment UDM field is set to GOOGLE_CLOUD_PLATFORM.
jsonPayload.endpoint.zone	principal.resource.attribute.cloud.availability_zone
jsonPayload.endpoint.region	principal.location.name
jsonPayload.connection.dest_ip	target.ip
jsonPayload.connection.dest_port	target.port
jsonPayload.destination.geo_location.city	target.location.city
jsonPayload.destination.geo_location.country	target.location.country_or_region
jsonPayload.destination.geo_location.region	target.location.name
jsonPayload.destination.geo_location.continent	target.labels [destination_geo_location_continent] (deprecated)
jsonPayload.destination.geo_location.continent	additional.fields [destination_geo_location_continent]
jsonPayload.destination.geo_location.asn	network.asn
jsonPayload.destination.instance.project_id	target.resource_ancestors.name	If the jsonPayload.destination.instance.project_id log field value is not empty, then the //cloudresourcemanager.googleapis.com/projects/%{jsonPayload.destination.instance.project_id} log field is mapped to the target.resource_ancestors.name UDM field.
	target.resource_ancestors.resource_type	If the jsonPayload.destination.instance.project_id log field value is not empty, then the target.resource_ancestors.resource_type UDM field is set to CLOUD_PROJECT.
	target.resource_ancestors.attribute.cloud.environment	If the jsonPayload.destination.instance.project_id log field value is not empty, then the target.resource_ancestors.attribute.cloud.environment UDM field is set to GOOGLE_CLOUD_PLATFORM.
jsonPayload.destination.instance.vm_name	target.hostname
jsonPayload.destination.instance.vm_name	target.asset.hostname
jsonPayload.destination.instance.vm_name	target.resource.name
	target.resource.resource_type	If the jsonPayload.destination.instance.vm_name log field value is not empty, then the target.resource_ancestors.resource_type UDM field is set to VIRTUAL_MACHINE.
	target.resource.attribute.cloud.environment	If the jsonPayload.destination.instance.vm_name log field value is not empty, then the target.resource.attribute.cloud.environment UDM field is set to GOOGLE_CLOUD_PLATFORM.
jsonPayload.destination.instance.zone	target.resource.attribute.cloud.availability_zone
jsonPayload.destination.instance.region	target.location.name	If the jsonPayload.destination.geo_location.region log field value is empty, then the jsonPayload.destination.instance.region log field is mapped to the target.location.name UDM field.
	security_result.action	If the jsonPayload.allocation_status log field value is equal to OK, then the security_result.action UDM field is set to ALLOW. Else, if the jsonPayload.allocation_status log field value is equal to DROPPED, then the security_result.action UDM field is set to BLOCK.
jsonPayload.allocation_status	security_result.action_details
labels	about.resource.attribute.labels
resource.labels.project_id	about.resource.attribute.labels [resource_project_id]	If the resource.labels.project_id log field value is not empty, then the //cloudresourcemanager.googleapis.com/projects/%{resource.labels.project_id} log field is mapped to the about.resource.attribute.labels.resource_project_id UDM field.
resource.labels.gateway_name	about.resource.attribute.labels [resource_gateway_name]

What's next

• Data ingestion to Google Security Operations