Packet Filtering Firewall
These firewalls observe packets without examining their contents to gain information such as their source, IP address, port number and protocol type. Unfortunately due to their inability to examine the contents of a network package, these firewalls are not effective against deeply planned attacks.
Proxy Firewall
These firewalls provide content caching and security to gateways from a network to another network for a specific application through its ability to prevent interference from outside networks. However, this type of firewall can limit throughput capabilities and restrict applications.
Stateful Inspection Firewall
These firewalls regulate network traffic through state, port and protocol. This regulation is performed throughout the entire opening and closing of a connection using administrative rules and context which it gains from previous connection regulation.
Web Application Firewall (WAF)
These firewalls act as the middle man between internal and external networks. Their job is to monitor the requests for the internal network. These firewalls have the ability to inspect packets for malicious or unauthorized data to provide a great layer of security. Unfortunately these firewalls tend to impact network performance due to their need for proxy servers.
Unified Threat Management (UTM) Firewall
These firewalls have the same foundation as the stateful inspection firewall with a better implementation of intrusion prevention and antivirus. They prioritise providing easy to use services.
Next Generation Firewall (NGF)
These firewalls are all of the above but with significant additions to their toolset. These firewalls have the ability to also perform tasks such as application awareness and control, enhanced intrusion prevention and URL filtered through geolocation.