https://cloud.google.com/vpc/docs/firewall-rules-logging#egress_deny_example You can only enable Firewall Rules Logging for rules in a Virtual Private Cloud (VPC) network. Legacy networks are not supported. Firewall Rules Logging only records TCP and UDP connections. Although you can create a firewall rule applicable to other protocols, you cannot log their connections. You cannot enable Firewall Rules Logging for the implied deny ingress and implied allow egress rules. Log entries are written from the perspective of virtual machine (VM) instances. Log entries are only created if a firewall rule has logging enabled and if the rule applies to traffic sent to or from the VM. Entries are created according to the connection logging limits on a best effort basis. The number of connections that can be logged in a given interval is based on the machine type. Changes to firewall rules can be viewed in VPC audit logs. https://cloud.google.com/vpc/docs/firewall-rules-logging#specifications