Firewall as a Service (FWaaS) is challenging the decades-old concept of the appliance as the primary form factor to deliver network security capabilities. FWaaS offers a single logical firewall that is available anywhere, seamlessly scales to address any traffic workload, enforces unified policy, and self-maintained by a cloud provider. It has been deployed in production deployments by several vendors, including Cato Cloud Cloud. It provides the necessary compute resources to perform all security processing on all traffic regardless of source or destination.
Source: https://thehackernews.com/2017/07/firewall-as-a-service.html