Azure Firewall is a managed, cloud-based OSI Layer 3 to 7 network security service that protects customer Azure VNet resources. It is a fully stateful firewall as a service with implemented high availability and unrestricted scalability in the cloud.
Customers can centrally create, enforce, and log application and network connectivity policies across subscriptions and virtual networks within one Tenant. Azure Firewall uses a static public IP address for a VNet resources, that allows outside firewalls to identify traffic originating from a VNet. The service is fully integrated within the Azure Monitoring services like Azure Monitor, that works as an interface and platform for logging and analytics.