What kind of firewall is the NSX Distributed Firewall described as?

The NSX Distributed Firewall is characterized as a stateful, in-kernel firewall. This means that it tracks the state of active connections and applies rules based on the context of those connections. A stateful firewall maintains a table of active sessions, allowing it to make more informed decisions about what traffic to allow or block based on the history of connections. This feature is crucial for handling dynamic protocols and ensuring more secure communication.

Being 'in-kernel' indicates that the firewall operates at a low level within the operating system's kernel, providing enhanced performance and efficiency. It directly interacts with the data path, enabling real-time traffic monitoring and enforcement of security policies at the virtual network level without the need to route traffic through an external security appliance. This design enhances scalability and reduces latency, making it suitable for environments that demand high throughput.

In summary, the combination of being stateful and in-kernel allows the NSX Distributed Firewall to efficiently secure traffic with a deep understanding of network sessions, which is essential for modern virtual data center environments.