What are the two main types of firewalls?

The two main types of firewalls that are widely recognized in cybersecurity are packet-filtering firewalls and stateful inspection firewalls. Packet-filtering firewalls operate at the network layer, examining packets of data and allowing or blocking them based on predefined rules such as source IP address, destination IP address, port numbers, and protocols. This type of firewall is relatively simple but does not maintain the context of ongoing connections.

In contrast, stateful inspection firewalls, also known as dynamic packet filtering firewalls, keep track of the state of active connections and make decisions based on both the context of the traffic and the rules. They maintain a state table to track the state of prior packets and ensure that only valid packets that are part of an established connection are allowed through. This provides a higher level of security as it recognizes and understands the complexities of traffic flow.

By understanding these two main types of firewalls, one can better appreciate the mechanisms involved in securing network infrastructure and the differing approaches to controlling traffic based on the rules and state of the connection.