A virtual firewall is a firewall device or service that provides network traffic filtering and monitoring for virtual machines. A virtual firewall is deployed, executed and operated from a virtual machine.
Techopedia explains Virtual Firewall
Virtual firewall formats include:
Integrated OS kernel component
A virtual security provider's dedicated hardware platform A virtual firewall operates in a virtual area network (VAN) environment of connected virtual machines. A virtual firewall operates in two different modes:
Bridge mode: Like a traditional firewall, this mode operates by diagnosing and monitoring all incoming and outgoing traffic bound for other virtual networks or machines.
Hypervisor mode: In contrast, this mode is isolated from the actual network, resides in the core hypervisor kernel and monitors the virtual host machine's incoming and outgoing traffic.