Securing Your Business with Cisco ASA and PIX Firewalls

Perimeter Traffic Filtering

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 ...