What characteristic defines the vulnerability of stateless packet filtering firewalls?

The defining characteristic of stateless packet filtering firewalls is their inability to track connection states. Unlike stateful firewalls, which remember the state of active connections and make decisions based on the context of the connection, stateless firewalls evaluate each packet independently of others. This means that they do not keep track of whether a packet is part of an existing connection or the first packet of a new connection.

As a result, stateless firewalls check packets against set rules (such as IP addresses and port numbers) but lack the capability to understand the state of communication. They operate purely on a rule-based system without any awareness of the dynamic nature of a session, leading to a simpler and often quicker filtering mechanism, but one that is less effective against certain types of attacks that exploit connection state or context.

This limitation means that while stateless firewalls can be quick and efficient for basic packet filtering, they might not adequately protect against more sophisticated threats that rely on the tracking of session states. Being aware of connection states is fundamental in a more comprehensive security strategy, thus highlighting the significance of knowing the limitations of stateless firewalls.