The original function of a security appliance was to filter traffic originating from a less-secure network, such as the Internet, and destined to the private inside network of a device. The ASA/PIX implements this default behavior in the following way, presenting a strong security posture:
Blocks all inbound traffic
Lets all stateful traffic pass from a secure interface to a less-secure interface (inside to outside) and then allows the traffic to return back to the secure interface
Enables customers to create their own traffic rules, depending on their requirements
This default behavior ensures that when an ASA/PIX is first installed, the private secure network is fully protected from attacks that might originate from ...