Firewall rules in GCP let you allow or deny traffic based on rules you apply to your instances. Firewall rules are applied at a networking level with every VPC network acting as a distributed firewall. Even though firewall rules are applied at a networking level, they allow/deny connections at an instance level. The advantage of a distributed firewall is that it does not only filter traffic between instances but also filters traffic between networks. All firewall rules are specific to a VPC network with each rule either allowing or denying traffic.
Firewall rules, being unique to a VPC network, cannot be shared between multiple VPC networks. It is important to note that firewall rules in GCP only support IPv4 traffic. There is also no logging mechanism for firewall rules; this means that you cannot log an Allow or a Deny action in the firewall. The GCP firewall allows...
