Stateful vs. Stateless Firewalls: What’s the Difference?

Firewalls come in two standard types, stateful and stateless. Stateless firewalls check packets individually before deciding whether or not to permit them, while stateful firewalls are able to track movement of packets around the network, building profiles to better recognize safe and unsafe connections at the source.

Firewalls are like club bouncers—they decide who gets in and stays out. Stateful firewalls are the experienced bouncer, who knows precisely who is coming and going and can recognize familiar faces. They keep track of all the connections that pass through them, ensuring that only authorized traffic is allowed to pass. 

Stateless firewalls, on the other hand, are the rookie bouncer who just checks ID at the door without keeping track of comings and goings. They don’t recognize any connections and simply check each packet individually to see if it matches their predetermined ruleset.

In general, stateful firewalls are the more secure of the two types, but they also require a more robust infrastructure to use effectively. For that reason, small and midsize businesses are often better suited to stateless firewalls.

5 Differences Between Stateful and Stateless Firewalls

We’ll review the technical definitions below, but first, here is a quick summary of the differences between stateful and stateless firewalls:

	Stateful firewall	Stateless firewall
Track the state of each connection	✔	✘
More granular controls over network	✔	✘
Inspect each packet individually	✘	✔
Examines and catalogs behavior	✔	✘
Resource intensive	✔	✘

Stateful Firewalls: Best for Enterprises

Stateful firewalls are better suited for larger enterprises since they provide more granular control over network traffic. They can track the state of each connection that passes through them, allowing them to differentiate between legitimate traffic and malicious attacks. They inspect everything inside data packets, the data characteristics, and communication channels. 

Stateful firewalls can actively monitor and filter out suspicious data packets while also cataloging the behaviors of legitimate packets. This enables them to track patterns to identify anomalies or irregularities more quickly and accurately. When a certain kind of traffic is approved, it’s added to an allowlist, which instructs the firewall to allow this type of traffic through without further inspection.

Stateful firewalls also let data packets connect multiple computers on the same internal network without opening up all ports on the firewall. However, they require more resources, which can be expensive to maintain and difficult to scale as your enterprise grows.

Advantages

Stateful firewalls offer several security advantages for enterprises large and small, including comprehensive protection, increased network performance, and easier troubleshooting.

• Provide comprehensive protection against malicious attacks
• Increase network performance (since only legitimate traffic is allowed to pass)
• Provide better control over traffic flow and can detect anomalies
• Can catalog and allowlist legitimate traffic, letting it bypass further inspection
• Easier to troubleshoot (since they keep track of all the connections passing through them)
• Learn as they operate, improving security over time

Disadvantages

However, stateful firewalls also have their drawbacks, such as being resource-intensive and requiring management to stay on top of new threats.

• Require more resources to operate
• Can increase network latency due to heavy resource usage
• Have a higher false positive rate
• Can be challenging to scale as your enterprise grows, and may not be able to detect encrypted traffic or new threats that emerge as technology advances
• Can be expensive, depending on the number of ports needed
• May be more vulnerable to man-in-the-middle (MITM) attacks

Top 3 common uses of stateful firewalls

Below are the most common uses of stateful firewalls.

Protection against malicious attacks 

Unsurprisingly, the primary use of a stateful firewall is to protect against malicious attacks. A good firewall can detect and block malicious traffic from entering or leaving your network. 

Firewalls can also block certain types of applications and protocols, such as peer-to-peer file-sharing programs, which can be used to distribute malware and other threats. 

Additionally, firewalls can detect suspicious activity and alert administrators if something unusual is happening on the network. 

Access control 

Stateful firewalls are also great for controlling who has access to your network. They allow administrators to set up rules for who can access certain network parts and what type of data they can access. This helps ensure that only authorized users can view sensitive information or make changes to the system. 

Additionally, firewalls can restrict access based on IP address or user credentials, allowing administrators to limit who has access without having to manage permissions for each user manually. 

Traffic management 

Finally, stateful firewalls can be used for traffic management purposes. For example, they can be configured to prioritize certain types of traffic over others to ensure that critical services have sufficient bandwidth available when needed. They can also be set up to block certain types of traffic altogether to prevent abuse or conserve resources.

Stateless Firewalls: Best for Small and Midsize Businesses (SMBs)

Stateless firewalls are best for many SMBs, since they’re cheaper and easier to manage. They don’t keep track of each connection’s state and instead inspect each packet individually. This makes them ideal for simpler networks with fewer computers since they don’t require as many resources to maintain.

However, their lack of contextual awareness also means that stateless firewalls can be less secure, as they are less effective at detecting malicious traffic trying to enter your network. If a packet doesn’t fit the preset parameters, there is a possibility that it will pass unnoticed, even if it exhibits other behaviors that could be malicious.

Advantages

Stateless firewalls are an excellent option for small and medium businesses since they are more cost-effective, require fewer resources, and are less prone to bog down smaller networks.

• Offer a lightning-fast response time due to the lack of deep analysis
• Work effectively even when traffic is at its peak
• Typically more cost-effective

Disadvantages 

However, due to their lack of context monitoring, they do have some drawbacks, principally around creating gaps in security and requiring substantial upfront configuration.

• Less secure than their stateful counterparts due to their inability to examine all network traffic and classify the data type, leading to gaps in security that attackers can readily exploit
• Configuring these firewalls to guard against potentially malicious traffic and cyberattacks may prove time-consuming and taxing, requiring that a knowledgeable individual administers this process

Top 4 common uses of stateless firewalls

Stateless firewalls are typically used for proxies, File Transfer Protocol (FTP), Network Address Translation (NAT), and network segmentation.

Proxy Firewall

Proxy firewalls are used to route network traffic between two or more computers. This allows businesses to protect their networks from outside threats, including malicious software and hackers, by providing a direct connection between clients.

FTP

FTP is a protocol that is used to transfer files over the internet. Stateless firewalls can be configured to allow only certain types of FTP traffic, like unencrypted connections or connections from certain IP addresses.

NAT

NAT is a method used to hide the internal IP address of a computer on the same local network but make it accessible to other networks. Stateless firewalls help protect against hackers by blocking incoming requests from outside sources that can access the internal IP address.

Network segmentation

Stateless firewalls can also be used to segment networks into different subnets, improving the overall security of your network by making it difficult for attackers to gain access to sensitive data or machines.

Who Should Use a Stateful vs. Stateless Firewall?

In general, stateful firewalls are more secure and reliable than their stateless siblings. However, their higher resource usage and monitoring requirements make them better suited for larger organizations and enterprises where data security is paramount. These firewalls can detect malicious traffic and protect against advanced attacks that stateless firewalls cannot detect, making them ideal for protecting sensitive information.

On the other hand, stateless firewalls may be suitable for smaller organizations or businesses with simpler networks that don’t require as much protection. Due to their simplicity, they offer a quick response time without sapping network bandwidth or demanding active IT monitoring—though businesses should be aware that they’re sacrificing a little bit of security.

Bottom Line: Choosing Between Stateful vs. Stateless Firewalls

When it comes down to selecting either a stateful or stateless firewall, it’s essential to consider the size and complexity of your network and what types of threats you’re trying to protect against. 

In most cases, larger organizations will be better off with stateful firewalls, while smaller organizations might prefer the cost-effectiveness of stateless firewalls. 

Whichever type you choose, it’s crucial to ensure that your firewall configuration is secure and up-to-date for maximum protection.

Businesses large and small can benefit from partnering with a managed security firm. Here are the best network security companies to trust with your organization’s data.