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

What's the difference between a stateful and a stateless firewall? Which one is the best choice to protect your business?
  • April 29, 2019

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.

Aren't all firewalls the same?

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.

What is a stateful firewall?

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.

What is a stateless firewall?

Stateless firewalls use clues from the destination address, source and other key values to assess whether threats are present, then block or restrict those deemed untrusted. Preset rules enforce whether traffic is permitted or denied, but the system is typically unable to determine the difference between truly desired communications and sophisticated attempts to disguise unauthorized communications as trusted ones. As one of the earlier iterations of firewalls, stateless firewalls don't look beyond the header of packet contents to determine if traffic is authorized.

Pros and Cons of Stateful vs. Stateless Firewalls

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.

Pros of Stateful Firewalls

+ 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.

Cons of Stateful Firewalls

- 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.

Pros of Stateless Firewalls

+ 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.

Cons of Stateless Firewalls

- 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.

Should you choose a stateless or stateful firewall?

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. 

Small Business Firewall Needs

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.

Enterprise Firewall Needs

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.

Other Scenarios for Choosing Stateless Firewalls

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).
Other Scenarios for Choosing Stateless Firewalls

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.

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.

Learn more about the Benefits of Next Generation Firewalls.

Protect Your Business Today

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.

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