Firewalls have been around for decades and, by comparison, next-generation firewalls (NGFWs) are a more recent evolution of basic firewalls. Today it is generally accepted that a legacy firewall is a packet filter that provides access control based on ports and protocols. An NGFW, on the other hand, includes all the basic firewall functionality with an added benefit of application inspection and other advanced features. Gartner published a definition along these lines but added the additional capabilities of intrusion detection and intelligence from outside the firewall (for example, correlation and analytics capabilities). (See https://www.gartner.com/it-glossary/next-generation-firewalls-ngfws.)
Cisco’s Adaptive ...