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

Stateful firewalls are capable of monitoring and detecting states of all traffic on a network to track and defend based on traffic patterns and flows. Stateless firewalls, however, only focus on individual packets, using preset rules to filter traffic.

Firewalls provide critical protection for business systems and information. Operating according to prewritten security rules, firewalls are applications that monitor and manage the traffic flowing into and out of your network. Understanding the differences between stateful vs. stateless firewall technology helps ensure your business is protected appropriately.

No, there are many types of firewalls. Incoming and outgoing traffic abides by various rules set within an organization's firewall. Likewise, different types of firewalls exist to ensure a best fit for a company's network and needs. In either case, these network security measures are designed to keep untrusted, corrupt files out while protecting the company's network assets.

Firewall types tend to be either network firewalls running on network hardware or host-based firewalls that rely on host computers to oversee traffic. When researching firewall types for your business, you may have discovered stateful and stateless firewalls. There is also a third firewall type — next-generation firewalls — which has become the most recommended type. Let’s take a closer look at each.

Stateful firewalls monitor all aspects of the traffic streams, their characteristics and communication channels. These firewalls can integrate encryption or tunnels, identify TCP connection stages, packet state and other key status updates.

A stateless firewall filters network traffic based solely on predefined rules without maintaining any knowledge of previous connections or sessions. It inspects each packet individually, making decisions solely based on criteria such as source and destination IP addresses, port numbers and protocols.

As with most compare and contrast scenarios, stateful and stateless firewalls each have their own strengths and weaknesses. Here are the pros and cons of stateless firewall vs. stateful firewall options.

• Stateful firewalls are highly skilled at detecting unauthorized attempts or forged messaging.
• The powerful memory retains key attributes of network connections.
• These firewalls do not need many ports open for proper communication.
• Stateful firewalls offer extensive logging capabilities and robust attack prevention.
• An intelligent system, stateful firewalls base future filtering decisions on the cumulative sum of past and present findings.

• Vulnerabilities may allow a hacker to compromise and take control over a firewall that is not updated with the latest software releases.
• Some stateful firewalls can be tricked to allow or even attract outside connections with an action as simple as viewing a webpage.
• Man-in-the-middle attacks may pose greater vulnerabilities.

• Stateless firewalls deliver fast performance.
• Heavy traffic is no match for stateless firewalls, which perform well under pressure without getting caught up in the details.
• Stateless firewalls have historically been cheaper to purchase, although these days stateful firewalls have significantly come down in price.

• Stateless firewalls do not inspect traffic.
• The stateless firewall also does not examine an entire packet, but instead decides whether the packet satisfies existing security rules.
• These firewalls require some configuration to arrive at a suitable level of protection.

Firewalls provide security for businesses of all sizes. Looking at the pros and cons of different types of firewalls can help to narrow down which is the best fit for your business. 

A small business such as a sole proprietorship or single-member LLC will benefit from a firewall to keep internal documents and systems safe while keeping out the bad guys. Considering the typically higher cost of the stateful firewall, it's reasonable that a stateless firewall instead would be a suitable choice for small business needs. Traffic volumes may be lower than a major enterprise, so incoming threats may also be fewer and farther between. The fast performance of a stateless firewall coupled with its ability to handle large loads make this firewall a possible choice for savvy small business owners.

Also known as dynamic packet filtering, stateful firewalls tend to offer better security features for corporations than stateless firewalls. These firewalls are powerful workhorses prepared to detect threats and confront them head-on. Sophisticated memory capabilities allow the firewall system to grow smarter over time. Continual traffic monitoring provides a thick layer of security that complements other protective measures for larger corporations. Robust attack prevention and logging capabilities empower network administrators to keep organizational assets intact.

Keep in mind that stateless firewall technology is somewhat outdated. That said, there are a few situations where this technology may be a viable option:

• A small office with few trusted people who are looking for routing capabilities could get by with a stateless firewall.
• Stateless firewalls may also be enough when used inside a network, residing between VLANs to add a bit more control but knowing that the external traffic is already being handled by a stateful (and preferably “next-gen” firewall).

While it’s important to understand the differences between stateless and stateful firewalls as well as their advantages, it’s also crucial to know that firewall technology has evolved. Next-generation firewalls provide users with greater protection than either stateful or stateless firewalls. Learn why you consider a next-generation firewall.

A primary limitation with stateful firewalls, for instance, is that they are "connection" based. In other words, much of the security information gathered by stateful firewalls is dependent on the connection and its state (i.e. the logical port assigned to the service being used). The problem this poses is that many modern applications can (and often do) use more than one port depending on the various services they might offer. They may also use non-conventional ports or even change ports during use.  

Next-generation firewalls move beyond the limitations of connection-based traffic inspection and instead allow you to focus on inspecting applications themselves. They also allow you to combine many security services like web filtering or intrusion prevention when inspecting traffic by application.

Fortifying your business assets with the right firewall is a crucial step in protecting your information, your equipment and your employees. Deciding between stateful vs. stateless firewalls gives your business the power to protect your network assets with open eyes. Browse through a wide selection of firewalls to determine which type will provide the best security and support for your organization.