Which three statements are correct about a Junos firewall filter?

A Junos firewall filter operates at the individual packet level, meaning it examines each packet separately as it passes through the device. This characteristic allows the filter to apply rules to each packet independently, without considering the context of previously seen packets or any existing connection states.

Therefore, statement A accurately describes the functionality of a Junos firewall filter. It emphasizes the filter's ability to enforce security policies by inspecting packets as they traverse the network, which is fundamental to how stateless filtering operates.

Regarding the other statements: while tracking connections (as mentioned in statement B) and permitting established connections automatically (as mentioned in statement C) are characteristics of stateful firewalls rather than stateless ones like a Junos firewall filter, the nature of a firewall filter being stateless is indeed emphasized in statement D. However, the essence of a stateless firewall is highlighted through the core action of examining packets individually, which makes statement A the most pertinent and accurate choice.