Private Google Access for on-premises hosts

On-premises hosts can reach Google APIs and services by using Cloud VPN or Cloud Interconnect from your on-premises network to Trusted Cloud. On-premises hosts can send traffic from the following types of source IP addresses:

  • a private IP address, such as an RFC 1918 address
  • a privately used public IP address, except for a Google-owned public IP address. (Private Google Access for on-premises hosts does not support re-using Google public IP addresses as sources in your on-premises network.)

To enable Private Google Access for on-premises hosts, you must configure DNS, firewall rules, and routes in your on-premises and VPC networks. You don't need to enable Private Google Access for any subnets in your VPC network as you would for Private Google Access for Trusted Cloud VM instances.

On-premises hosts must connect to Google APIs and services by using the virtual IP addresses (VIPs) for either the restricted.googleapis.com or private.googleapis.com domains. Refer to Private Google Access-specific domains and VIPs for more details.

Google publicly publishes DNS A records that resolve the domains to a VIP range. Even though the ranges have external IP addresses, Google does not publish routes for them. Therefore, you must add a custom advertised route on a Cloud Router and have an appropriate custom static route in your VPC network for the VIP's destination.

The route must have a destination matching one of the VIP ranges and a next hop being the default internet gateway. Traffic sent to the VIP range stays within Google's network instead of traversing the public internet because Google does not publish routes to them externally.

For configuration information, see Configure Private Google Access for on-premises hosts.

Supported services

Services available to on-premises hosts are limited to those supported by the domain name and VIP used to access them. For more information, see Domain options.

Example

In the following example, the on-premises network is connected to a VPC network through a Cloud VPN tunnel. Traffic from on-premises hosts to Google APIs travels through the tunnel to the VPC network. After traffic reaches the VPC network, it is sent through a route that uses the default internet gateway as its next hop. This next hop allows traffic to leave the VPC network and be delivered to restricted.googleapis.com (199.36.153.4/30).

Private Google Access for hybrid cloud use case.
Private Google Access for hybrid cloud use case (click to enlarge).
  • The on-premises DNS configuration maps *.googleapis.com requests to restricted.googleapis.com, which resolves to the 199.36.153.4/30.
  • Cloud Router has been configured to advertise the 199.36.153.4/30 IP address range through the Cloud VPN tunnel by using a custom advertised route. Traffic going to Google APIs is routed through the tunnel to the VPC network.
  • A custom static route was added to the VPC network that directs traffic with the destination 199.36.153.4/30 to the default internet gateway (as the next hop). Google then routes traffic to the appropriate API or service.
  • If you created a Cloud DNS managed private zone for *.googleapis.com that maps to 199.36.153.4/30 and have authorized that zone for use by your VPC network, requests to anything in the googleapis.com domain are sent to the IP addresses that are used by restricted.googleapis.com. Only the supported APIs are accessible with this configuration, which might cause other services to be unreachable. Cloud DNS doesn't support partial overrides. If you require partial overrides, use BIND.

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