Adaptive Security Algorithm
The Adaptive Security Algorithm (ASA) is the key to stateful connection control on the Cisco
Security Appliance. The ASA creates a stateful session flow table (also called the state table).
Source and destination addresses and other connection information are logged in to the state
table. By using the ASA, the Cisco Security Appliance can perform stateful filtering on the
connections in addition to filtering packets. Additionally, the ASA generates random TCP
sequence numbers for outbound traffic by making it look like a response to an outbound
request is unlikely to succeed.