cloud-foundation-fabric/networking/filtering-proxy

Network filtering with Squid

This example shows how to deploy a filtering HTTP proxy to restrict Internet access. Here we show one way to do this using a VPC with two subnets:

• The first subnet (called "apps" in this example) hosts the VMs that will have their Internet access tightly controlled a non-caching filtering forward proxy.
• The second subnet (called "proxy" in this example) hosts a Cloud NAT instance and a Squid Server Squid.

The VPC is a Shared VPC and all the service projects will be located under a folder enforcing the compute.vmExternalIpAccess (organization policies)[https://cloud.google.com/resource-manager/docs/organization-policy/org-policy-constraints]. This prevents the service projects from having external IPs thus forcing all outbound Internet connections through the proxy.

To allow Internet connectivity to the proxy subnet, a Cloud NAT instance is configured to allow usage from (that subnet only)[https://cloud.google.com/nat/docs/using-nat#specify_subnet_ranges_for_nat]. All other subnets are not allowed to use the Cloud NAT instance.

To simplify the usage of the proxy, a Cloud DNS private zone is created and the IP address of the proxy is exposed with the FQDN proxy.internal.

You can optionally deploy the Squid server as (Managed Instance Group)[https://cloud.google.com/compute/docs/instance-groups] by setting the mig option to true. This option defaults to false which results in a standalone VM.