Stateful vs. Stateless Firewall – Full Comparison in 2023


By Jack Lin

Update on

Stateful vs. Stateless Firewall

In our interconnected world, network security is incredibly important. With increasing cyber threats, it’s crucial for both businesses and individuals to protect their data and systems from unauthorized access and potential attacks.

Firewalls are key to boosting network security, with two main types: stateless firewall and stateful firewall.

In this piece, we’ll look at the main distinctions between these firewall types and help you determine which is better suited to your specific security requirements.

What is a Firewall?

Before exploring the distinctions between stateless and stateful firewalls, let’s grasp the concept of a firewall.

A firewall is a security tool or software that acts as a shield between a trusted internal network and an untrusted external network, like the internet.

It oversees and manages incoming and outgoing network traffic using predefined security rules, permitting or obstructing data packets based on different criteria.

Stateless Firewall

A stateless firewall, also called a packet filter firewall, is the simplest kind. It works at the network layer (Layer 3) of the OSI model and decides based on individual packets, without looking at the full communication context.

How Does a Stateless Firewall Work?

A stateless firewall examines the headers of individual data packets, such as the source and destination IP addresses, port numbers, and protocol information.

It then compares this information against its predefined rules to determine whether the packet should be allowed or denied.

However, it doesn’t keep track of the state or context of previous packets, treating each packet independently.

Pros of a Stateless Firewall

  • Simplicity: Stateless firewalls are easy to configure and implement due to their straightforward rule-matching process.
  • Low Overhead: Since they don’t maintain session state information, they have lower memory and processing requirements.

Cons of a Stateless Firewall

  • Limited Security: Stateless firewalls may not be effective in preventing certain sophisticated attacks that require session tracking and context analysis.
  • Lack of Granularity: They offer limited control over specific applications and services as they can only filter packets based on basic header information.

Stateful Firewall

A stateful firewall, also referred to as a dynamic packet filter firewall, is an enhanced kind of firewall that functions at the network and transport layers (Layer 3 and Layer 4) of the OSI model. In contrast to stateless firewalls, stateful firewalls keep a state table, which records the context of ongoing network connections.

How Does a Stateful Firewall Work?

A stateful firewall checks packet headers like a stateless firewall, but goes further by analyzing packet state. It monitors network connections and keeps a record of established ones, helping it decide whether to allow or block packets more effectively.

Pros of a Stateful Firewall

  • Enhanced Security: Stateful firewalls provide better protection against complex threats by analyzing packet data in the context of the entire session.
  • Application Awareness: They can identify and control specific applications, making them more versatile in managing traffic.

Cons of a Stateful Firewall

  • Higher Resource Consumption: The stateful inspection process requires more memory and processing power, leading to higher hardware costs.
  • Complex Configuration: Setting up and maintaining a stateful firewall can be more complex compared to a stateless firewall.

Besides, if you want to know more about the Function of the Firewall, just read more.

Comparison: Stateless vs. Stateful Firewall

Let’s compare stateless and stateful firewalls across various parameters to understand their differences better.

Security Approach

Stateless firewalls filter packets using basic header details, which might not be enough against advanced threats. On the other hand, stateful firewalls offer better security with a broader approach, as they take into account connection context and state.

Packet Filtering

Stateless firewalls filter packets using packet headers only, while stateful firewalls consider both headers and the status of active connections. This makes stateful firewalls more effective in allowing or blocking packets based on the established session state.


Stateless firewalls usually need fewer resources, leading to improved performance and lower delays. In contrast, stateful firewalls require more resources due to their detailed inspection process, which affects performance.


Stateful firewalls provide more flexibility for handling traffic and controlling specific applications since they understand active connection states. Stateless firewalls, with less context awareness, might not offer this same level of flexibility.

Which Firewall Should You Choose?

The choice between a stateless and stateful firewall depends on your specific security requirements and the nature of your network. If your primary concern is simplicity and resource efficiency, a stateless firewall may be sufficient.

However, if you require a more robust security solution with better application control, a stateful firewall is the preferable option.


The main function of a firewall is to monitor and control network traffic, allowing or blocking data packets based on predefined security rules, thereby protecting the network from unauthorized access and cyber threats.

Yes, using both stateless and stateful firewalls together is known as a layered defense approach, providing an added layer of security by leveraging the strengths of each type of firewall.

While firewalls are a critical component of network security, they are not sufficient on their own. Employing multiple security layers, including firewalls, antivirus software, and intrusion detection systems, is recommended for comprehensive protection.

Firewall rules should be regularly reviewed and updated to adapt to the changing threat landscape. It is best practice to perform updates at least quarterly or whenever significant changes occur in the network.

While firewalls are effective in blocking many common cyber threats, they cannot guarantee protection against all types of attacks. Staying informed about the latest threats and implementing additional security measures is crucial for a robust defense.


To sum up, both stateless and stateful firewalls are crucial for network security. Stateless firewalls are basic with less overhead, yet might not suffice against advanced threats.

In contrast, stateful firewalls offer better security and application control but need more resources. When deciding, evaluate your security needs and available resources for an informed choice.


10 years of experience in information and computer technology. Passionate about electronic devices, smartphones, computers, and modern technology.