5 reasons to use a stateless firewall (+3 key disadvantages)

In networking, “state” refers to the context or session data of a current network connection. Therefore, a stateful firewall keeps track of the state of each connection that passes through it, while a stateless firewall does not.

Although they may seem less restrictive, stateless firewalls are incredibly useful for protecting home and business networks. They use ACLs (access control lists) to determine what traffic to allow and what traffic to block.

Of course, not tracking the state of network connections means that stateless firewalls can't tell you as much about the traffic on your network as stateful firewalls. The benefits of stateless firewalls come with tradeoffs.

Enterprises often balance these trade-offs by using both types together, with stateless firewalls that handle bulk traffic filtering at the perimeter and stateful firewalls that offer deeper inspection behind them.

By the end of this post, you'll know when stateless firewalls work really well and when another solution might work much better.

Five reasons to use a stateless firewall

1. They are efficient

The biggest advantage of using a stateless firewall is efficiency. Because they only check individual packets (rather than tracking the status of connections like their bulky stateful counterparts), stateless firewalls are like simple, stingy security machines.

This makes them much more useful when handling large volumes of traffic. For example, because they don't have to keep up with the specific details of every connection that passes through, stateless firewalls won't consume as much memory or processing power.

If you're running a large-scale website that receives tons of traffic, for example, you don't want your firewall to slow things down. With a stateless firewall, you can configure strong network security protections without compromising the performance of a website.

SEE: Avoid these mistakes when setting up network security.

2. Stateless firewalls are easy to configure and maintain

Setting up a stateless firewall is very easy compared to stateful firewalls.

Stateful firewalls dynamically maintain state tables to track ongoing connections, ensuring that traffic flows are legitimate by monitoring session information.

In contrast, stateless firewalls rely on a fixed set of filtering rules, such as allowing or blocking packets based on IP addresses, ports, or protocols. This makes stateless firewalls simpler to configure and requires fewer resources, but it also makes them less adaptable to dynamic or context-dependent traffic than stateful firewalls.

3. Stateless excels at the network perimeter

Stateless firewalls are often used as the first line of defense in network security due to their simplicity and effectiveness in blocking unwanted traffic.

They are particularly useful in scenarios where only basic access control is needed, such as filtering traffic between trusted and untrusted networks. This protects specific services from common attacks such as port scans, denial of service (DoS) attacks, or VoIP fraud.

While they may not offer the deep inspection or session awareness of stateful firewalls, they can serve as an effective initial barrier, reducing the load on more advanced systems by blocking simple, high-volume threats before they reach most sensitive parts of the network.

4. They are inherently less vulnerable

Stateless firewalls do not track past traffic or active connections, making them less prone to certain types of attacks targeting the firewall's memory or stored data.

Instead, stateless firewalls simply check incoming packets against their predefined “allow” and “deny” rules, ensuring that traffic is only allowed to enter the network if it meets specific criteria. This simple approach ensures that only authorized traffic enters the network.

Because they do not need to manage the details of each connection, stateless firewalls avoid some of the vulnerabilities that can arise when a firewall tries to remember everything, such as becoming overloaded during different types of DDoS attacks, where attackers flood the system with too many requests.

Stateful firewalls offer deeper inspection and more comprehensive security, but that introduces additional complexity that attackers can exploit. Stateless firewalls, with their simpler design, avoid this risk entirely.

5. Stateless firewalls are cost-effective and affordable

Because they do not require the advanced features of stateful firewalls, such as session tracking or deep packet inspection, their hardware and maintenance costs are significantly lower. This makes them an affordable option for organizations with limited IT budgets or smaller networks.

Stateful firewalls are more expensive due to their advanced features such as built-in intrusion detection and prevention systems. These firewalls also require more processing power, memory, and specialized hardware to handle real-time traffic analysis and maintain security.

Key Disadvantages of a Stateless Firewall

While stateless firewalls have their advantages, they also have some disadvantages.

1. Minimum packet inspection capabilities

Since it does not keep track of connections, a stateless firewall will not maintain a table of all previous connections that have passed through the firewall. This makes it faster and easier to handle large volumes of traffic, but comes with minimal packet inspection capabilities.

For example, stateless firewalls can only inspect individual packets based on headers and protocols, which means they cannot examine the contents of the packets themselves. This makes them less effective at detecting and preventing more sophisticated attacks that can bypass simple packet inspection, such as those that use encrypted traffic.

Additionally, due to the lack of connection tracking, a stateless firewall cannot always distinguish between legitimate and malicious traffic. This can lead to unnecessary blocking of legitimate traffic, which can disrupt business operations. It also makes it more difficult to modify the firewall, since stateless firewalls cannot recognize connection states, so they cannot dynamically allow or deny traffic based on them. Learn more about how stateful inspection works.

2. Harder to climb

One of the biggest disadvantages of stateless firewalls is that scaling them can be an absolute nightmare in certain scenarios.

The problem lies in the fact that a stateless firewall only examines individual packets to determine whether to allow or reject them. This means that as the number of connections to your network increases, the number of rules in your firewall also increases. Therefore, when your network has a high volume of traffic, it can be extremely difficult to manage and maintain.

Unfortunately, with stateless firewalls, it is necessary to create manual rules for each type of packet traveling through the network. This can lead to a situation where there are simply too many rules to manage, which can lead to network performance issues, security breaches, and massive administrative overhead. Learn more about how to create a firewall policy that works for your network.

3. Initial setup to work properly

Although stateless firewalls are very easy to configure compared to stateful firewalls, the process is not exactly the easiest.

Stateless firewalls can require quite a bit of initial configuration to work properly. For example, because they do not maintain connection states, they must rely on other factors, such as IP addresses and port numbers, to determine whether or not to allow incoming packets on the network.

This means that in addition to the filtering rules mentioned above, some additional settings require careful configuration to ensure that legitimate traffic is allowed to pass while malicious traffic is blocked. Learn more about how to properly configure a firewall.