Cisco IOS Firewall feature set

The Cisco IOS Firewall Feature Set can be added to the existing IOS to provide the functionality of a firewall without expensive hardware upgrades. The Cisco IOS Firewall Feature Set has two components:

Intrusion Detection is the optional module of the Cisco IOS Firewall Feature Set.

https://www.ciscopress.com/articles/article.asp?p=26533

https://forum.networklessons.com/t/cisco-cbac-configuration-example/1079/20?u=lagapides

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/sec_data_cbac_fw/configuration/15-mt/sec-data-cbac-fw-15-mt-book/sec-cbac-insp-traf.html#GUID-3FB737CE-786D-4385-BAF8-2910CFD80B68