Do you need to discover what IP netblocks are owned and operated by Google to perhaps add to your firewall ACLs?

With dynamic zones available in Shorewall, you are able to define firewall rules and to filter network traffic based on the domain name. For example, you can permit IMAPS connection only to gmail.com domain. Problem is that Google cluster is very big and you are always connecting to different IP address. So you can’t define static rules for traffic filtering.

Here is little HOWTO do this.
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