What is the difference between a stateful inspection firewall and a packet filtering firewall?

Protecting business networks has never come with higher stakes. The average cost for stolen digital files containing sensitive proprietary information has risen to $148 each. When you consider how many files cybercriminals may get away with in a given attack, the average price tag of $3.86 million per data breach begins to make sense.

Given that, it’s important for managed services providers (MSPs) to understand every tool at their disposal when protecting customers against the full range of digital threats. While each client will have different needs based on the nature of their business, the configuration of their digital environment, and the scope of their work with your team, it’s imperative that they have every possible defense against increasingly malicious bad actors.

Computer firewalls are an indispensable piece of network protection. By protecting networks against persistent threats, computer firewalls make it possible to weed out the vast majority of attacks levied in digital environments. Although firewalls are not a complete solution to every cybersecurity need, every business network should have one.

However, not all firewalls are the same. They can often be broken down into stateful firewall vs. stateless firewall options. Each has its strengths and weaknesses, but both can play an important role in overall network protection.

What does stateful firewall mean?

A stateful firewall is a firewall that monitors the full state of active network connections. This means that stateful firewalls are constantly analyzing the complete context of traffic and data packets, seeking entry to a network rather than discrete traffic and data packets in isolation.

Once a certain kind of traffic has been approved by a stateful firewall, it is added to a state table and can travel more freely into the protected network. Traffic and data packets that don’t successfully complete the required handshake will be blocked. By taking multiple factors into consideration before adding a type of connection to an approved list, such as TCP stages, stateful firewalls are able to observe traffic streams in their entirety.

However, this method of protection does come with a few vulnerabilities. For example, stateful firewalls can fall prey to DDoS attacks due to the intense compute resources and unique software-network relationship necessary to verify connections.

What is the main difference between stateful and stateless packet filtering methods?

Stateless firewalls are designed to protect networks based on static information such as source and destination. Whereas stateful firewalls filter packets based on the full context of a given network connection, stateless firewalls filter packets based on the individual packets themselves.

To do so, stateless firewalls use packet filtering rules that specify certain match conditions. If match conditions are met, stateless firewall filters will then use a set of preapproved actions to guide packets into the network. If match conditions are not met, unidentified or malicious packets will be blocked.

Because stateless firewalls do not take as much into account as stateful firewalls, they’re generally considered to be less rigorous. For example, stateless firewalls can’t consider the overall pattern of incoming packets, which could be useful when it comes to blocking larger attacks happening beyond the individual packet level.

Is Windows Firewall stateful or stateless?

For many private or SMB users, working with the firewalls provided by Microsoft is their primary interaction with computer firewall technology. For several current versions of Windows, Windows Firewall (WF) is the go-to option. WF is a stateful firewall that automatically monitors all connections to PCs unless configured to do otherwise.

For users relying on WF, the platform will log the information of outgoing packets, such as their intended destination. When information tries to get back into a network, it will match the originating address of incoming packets with the record of destinations of previously outgoing packets. This helps to ensure that only data coming from expected locations are permitted entry to the network.

Check out our blog for other useful information regarding firewalls and how to best protect your infrastructure or users. 

A firewall is an access control technology that secures a network by only allowing certain types of traffic to pass through them. The internet is filled with cyber threats and can only be safely accessed if certain types of data are kept out. Otherwise, malware could get into your network and then spread to the various devices connected to it.

Firewalls accomplish this control by inspecting data packets, which are basically collections of data that include instructions on how to handle the data as it travels to its destination. The data within the packets can be inspected by the firewall to see if it contains threats. Part of this process involves checking how the data should connect to and move through the network. 

Whether it is how the data behaves or something within the data itself, a firewall can examine each packet and decide whether or not it poses a threat. Data being used by a malicious entity, once identified by the firewall, can be discarded, thus protecting the network.

Aren't all Firewalls the Same?

There are several different kinds of firewalls. The organization’s firewall has to be chosen according to what works best for the company’s objectives. One type is a network firewall, which runs on network hardware. Another type is host-based, which runs on a host computer and filters network traffic from within that computing environment. 

There are also next-generation firewalls (NGFWs) that empower you to inspect both data and applications, as well as incorporate intrusion prevention and web filtering during the inspection process.

A stateful firewall inspects everything inside data packets, the characteristics of the data, and its channels of communication. Stateful firewalls examine the behavior of data packets, and if anything seems off, they can filter out the suspicious data. Also, a stateful firewall can track how the data behaves, cataloging patterns of behavior. 

If a data packet examination reveals suspicious behavior—even if that kind of behavior has not been manually inputted by an administrator—the firewall can recognize it and address the threat. A stateful firewall can be used at the edge of a network or within, as is the case with an internal segmentation firewall (ISFW), which protects specific segments of the network in the event malicious code gets inside.

What is a Stateless Firewall?

Stateless firewalls make use of a data packet's source, destination, and other parameters to figure out whether the data presents a threat. These parameters have to be entered by either an administrator or the manufacturer via rules they set beforehand. 

If a data packet goes outside the parameters of what is considered acceptable, the stateless firewall protocol will identify the threat and then restrict or block the data housing it.

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Pros and Cons of a Stateful vs. Stateless Firewall

Stateless firewalls make use of information regarding where a data packet is headed, where it came from, and other parameters to figure out whether the data presents a threat. These parameters have to be entered by either an administrator or the manufacturer via rules they set beforehand. 

If a data packet goes outside the parameters of what is considered acceptable, the stateless firewall can identify the threat and then restrict or block the data housing it.

Pros of Stateful Firewalls

1. Stateful firewalls can detect when illicit data is being used to infiltrate the network.
2. A stateful inspection firewall also has the ability to log and store important aspects of network connections.
3. Stateful firewalls have no need for many ports to be open to facilitate smooth communication.
4. A stateful network firewall can log the behavior of attacks and then use that information to better prevent future attempts. This is one of the biggest advantages of stateful vs. stateless. Example application include being able to automatically deter a specific cyber attack in the future once it encountered it, without the need for updates.  
5. A stateful firewall learns as it operates, which enables it to make protection decisions based on what has happened in the past. This makes it a potentially powerful unified threat management (UTM) firewall solution, which is a single device that performs several security functions.

Cons of Stateful Firewalls

1. Unless a stateful firewall has the latest software updates, vulnerabilities can allow it to be compromised by a hacker and then controlled.
2. In the case of some stateful firewalls, they can be fooled into allowing a harmful connection to the network.
3. Stateful firewalls may be more susceptible to man-in-the-middle (MITM) attacks, which involve an attacker intercepting a communication between two people to either spy on the traffic or make changes to it.

Should you Choose a Stateful or Stateless Firewall?

Now that you know the difference between stateful and stateless firewall protocols, which is better? There are certain considerations to keep in mind when deciding which firewall to deploy within your organization.

Individual Firewall Needs

An individual is probably okay using a stateless firewall, particularly because stateful firewalls often cost more. However, it is important to remember this: A stateful firewall offers an “intelligent” solution. It learns how to filter traffic based on what has happened in the past and what it sees as it inspects incoming data. 

On the other hand, a stateless firewall, in many instances, may need to be carefully configured by someone familiar with the kinds of traffic and attacks that impact the network. This may necessitate that the individual learns more about firewalls before using a stateless one. This may require extra work they may not have the time or energy to perform.

Stateful vs. Stateless Firewall Needs for Small Business

As for small business firewalls, companies may want to lean more toward a stateless firewall for affordability. Because there is bound to be less incoming traffic than with a large enterprise, there may also be fewer threats. This could make them relatively straightforward to set up by a small business owner.

Stateful vs. Stateless Firewall Needs for Enterprise

For larger enterprises, stateful firewalls are the better choice. Because they offer dynamic packet filtering, they can adapt to a variety of threats using data gathered from previous network activity to ascertain the danger level of novel threats.

Fortinet Firewalls

Fortinet offers different types of firewalls, each designed to suit different types of network architecture. The FortiGate NGFW features can prevent malware from penetrating your network while automatically updating to adjust to the constantly evolving threat landscape. In this way, FortiGate offers flexible protection that keeps it a step ahead of attackers.

Fortinet also provides users with a web application firewall (WAF), which secures business-critical applications from zero-day threats, OWASP Top 10 attacks, and known and unknown vulnerabilities. Thus, the Fortinet WAF protects both desktop and mobile internet users, as well as the application programming interfaces (APIs) on which many businesses depend for uninterrupted operation. In this way, a WAF safeguards sensitive data from exposure, injection attacks, and the usage of components containing known vulnerabilities.

Modern businesses are often fueled by applications. The applications can be based on an on-premises server or situated within a variety of cloud infrastructures. The ability of the organization and the people and businesses it serves to access the applications securely is imperative to the smooth functioning of the organization. This necessitates a responsive, adaptable networking and security solution.

To meet this need, Fortinet offers a combination of software-defined wide-area networking (SD-WAN) and an NGFW. This provides your organization with adaptive cloud security, enabling you to deploy whichever application you need to the cloud of your choice without sacrificing security. Users can enjoy the protection of an NGFW regardless of the kind of device they are using or where the application is hosted.

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