Remember, adding security methods does not necessarily mean an increase in security. Additional mechanisms may increase, decrease, or leave unaffected the security posture of the firewall. Buyers should read the functional summaries provided by vendors for more details of how a particular product is designed. Also, bear in mind that all ICSA certified firewalls have passed the same set of tests, regardless of the product type or design philosophy. Summary All the types of firewalls are functionally equivalent.
Packet filters are least granular.
Application gateway firewalls are the most granular. A Packet Inspection firewall can be made almost as granular as an application gateway firewall. However, just because a particular product is characterized as a particular type of firewall does not mean that it does all of the security processing possible with that kind of firewall. Site Privacy and Policy Information.