Types of Firewalls: Everything You Need to Know

Using cybersecurity services and tools like firewalls has become necessary for modern users and businesses, given the increasing number of attacks worldwide.

If you don’t take security seriously for your individual devices or organizational network, security mishaps can happen, and you may lose your data, money, and reputation.

Using a firewall, you can secure your systems, networks, and data. Firewalls are of different types, and oftentimes, people are confused about what to choose between them

This is why it’s important to understand each type of firewall to make your decision.

So, let’s talk about different types of firewalls, their advantages, limitations, use cases, and service providers.

What Is a Firewall?

A firewall or network firewall is a security tool or device that sits between your network and the outside world. Acting like a secure “wall” or boundary, this cybersecurity system monitors all the incoming and outgoing web traffic passing through it in order to block harmful data packets.

A firewall blocks data packets based on some predefined rules that you can set. These tools help protect all your devices, data, and network from cyberattacks like insider threats, malware, social engineering attacks, DDoS, zero-day threats, etc. Thus, you can experience safe internet browsing.

Based on operational techniques, a firewall can be categorized as :

• Packet-filtering firewalls
• Stateful inspection firewalls
• Circuit level firewalls
• Proxy firewalls
• Next-generation firewalls (NGFWs)

Based on the delivery model, they can be:

• Software-based firewalls
• Hardware-based firewalls
• Cloud-based firewalls

Other types of firewalls are also available, such as host-based firewalls, UTM firewalls, NAT firewalls, WAFs, virtual firewalls, database firewalls, container firewalls, etc.

Packet-Filtering Firewalls

Packet-filtering firewalls are the oldest firewalls that can monitor and control incoming and outgoing data as it flows across a network. It creates a checkpoint or filter at a network switch or traffic router. It filters data based on some predefined rules and works at the network layer.

This type of firewall checks every single data packet that comes in or goes out of the network. It inspects data such as source and destination IP address, port number, type of packet, network protocol, etc., without opening the data packet.

If the data packet passes the inspection and there’s nothing suspicious about it, the packet-filtering firewall will allow it to pass through. However, if the data packet is found to be carrying some suspicious content, the firewall will drop or restrict the packet from entering the network. 

Advantages

• Simple, easy-to-use firewalls
• Packet-filtering firewalls need fewer resources to operate
• Don’t impact the performance of the system they are installed in

Limitations

These firewalls are easier to bypass.

Use Cases

Packet filtering firewalls are best useful for small networks, home networks, or where there’s a need for basic security from threats.

Providers: Cisco, WatchGuard Network Security

Circuit-Level Gateways

Circuit-level firewall monitors and inspects TCP handshakes in a network or other session initiation activities through a network protocol across a given network. It operates in the 5^th layer of the Open Systems Interconnection (OSI) model, called the session layer.

These firewalls sit between the remote and local hosts and can easily determine whether an initiated session is legitimate or not, and you should trust the remote system or not. This offers a quick way to detect malicious content and prevent security mishaps.

Like packet-filtering firewalls, circuit-level gateways are also simpler and can deny or approve traffic at speed without consuming high computational resources. 

Advantages

• Simple and faster
• Require less resources
• Lower impacts on end-user experience

Limitations

This type of firewall doesn’t check the data packet itself. If the TCP handshake is fine even though the packet has malware, the firewall will allow it to pass through the network.

Use Cases

Circuit-level gateways are helpful in centralizing the security and management policy without requiring third-party tools.

If your budget is low, but you require a firewall for your home or basic security needs, you can go for this firewall.

Providers: ForcePoint, Juniper Networks, etc.

Stateful Inspection Firewalls

Stateful inspection firewalls are the ones that can handle dynamic data and monitor packets continuously across the network. This is why they are also called dynamic packet filtering firewalls. It works at the network and transport layer.

Stateful inspection firewalls perform two types of verifications to validate if the incoming data packet is legitimate or not:

• A TCP handshake
• Data packet inspection

This way, stateful inspection firewalls create a greater level of security, restricting malware or illegitimate session initiations from happening. They can also recognize patterns to detect and block harmful content.

Advantages

• Greater protection
• Continuous, deeper monitoring and control
• For incoming and outgoing traffic, you don’t need to open several ports

Limitations

• Consumes more computation resources
• Reduced speed
• Can be expensive

Use Cases

It’s suitable for all types of networks and organization sizes. It’s also quite effective in defending against attacks like DoS.

Providers: Barracuda, Juniper Networks

Proxy Firewalls

Proxy firewalls are also called reverse-proxy firewalls or application-level gateways. These firewalls work at the application layer of the OSI model.

This firewall filters incoming web traffic between its source and your network and is deployed through the cloud or a proxy service. It first sets connections to the traffic source and checks incoming packets.

Like stateful firewalls, it also performs both packet inspection and TCP handshakes. However, these firewalls can also inspect data packets at a deep layer to check all the contents of a data packet in order to detect any malware or other risks.

After completing the inspection, if the data packet is found to be legitimate, it will be approved and it will reach the destination. If not approved, the packet will be rejected.

Advantages

• Thoroughly monitoring devices and data packets
• Maintains user anonymity
• Offers fine-grained security

Limitations

• Reduced system speed and performance due to extra steps during data transfer
• Doesn’t support every network protocol
• Expensive

Use cases

Proxy firewalls are suitable for internet browsing environments and securing resources from risks like web application threats.

Providers: Fortinet, Juniper Networks, F5 Networks

Next-Generation Firewalls (NGFWs)

Next-generation firewalls are the latest firewalls that offer all-around protection from threats, whether it’s from inside or outside of your network. It combines the capabilities of traditional firewalls along with modern security systems and software. Except for the physical layer, it works at all layers.

It offers a multilayer approach to securing your network from threats.

NGFWs include these main aspects:

• Traditional firewall features
• Intrusion prevention
• Application monitoring

These firewalls combine traditional firewall capabilities like deep data packet filtering, network address translation (NAT), TCP handshakes, virtual private networks (VPNs), URL blocking, quality of service (QoS) features, IDS, IPS, antivirus, SSH and SSL inspection, and reputation-based malware inspection.

Advantages

• Traffic inspection from layers 2 to 7 in the OSI model, i.e., data link layer to application layer
• Detecting and blocking advanced threats such as DDoS, zero-day attacks, etc.
• Enhanced control and visibility over traffic

Limitations

• Needs a high level of expertise to configure and run NGFWs
• Slow network performance
• Higher cost
• Requires heavy processing power

Uses Cases

NGFWs are suitable for all types of networks, especially for organizations requiring advanced security capabilities.

It’s also ideal for companies like banks, healthcare institutions, government agencies, etc., that come under heavily regulated industries and are required to meet compliance regulations.

Providers: Heimdal Security, Fortinet, Palo Alto Networks

Software-Based Firewall

Software-based firewalls are the ones you install on your local device and not a cloud server or an individual hardware component. It isolates each network endpoint from each other, making it an effective tool to create deep security.

Software-based firewalls run on another device or on a server where data protection is necessary. For this, it consumes some amount of computing resources like RAM and CPU. It monitors software programs executing on the host computer and filters incoming and outgoing traffic.

This firewall is efficient at working with applications on a system, managing users, blocking apps, monitoring users within your network, generating logs, and more.

Advantages

• Security at a deeper level
• Easy to configure, refigure, and use
• Less costly

Limitations

• Time-consuming and tough to maintain firewalls 
• Compatibility issues with other software installed 

Use Cases

Software-based firewalls are suitable for small businesses and individuals who want to avoid the complexity of traditional firewalls and have limited budgets.

Providers: Avast                             

Hardware Firewall

Hardware firewalls are physical devices that an organization deploys in order to create a secure network boundary or “firewall”. It inspects all the incoming and outgoing network traffic so that no harmful data packet can enter the boundary.

To offer enhanced protection, it also enforces security policies and access controls. You can monitor all the activities through a centralized control panel.

Like software firewalls, hardware firewalls also are installed between your device and the external world. It’s also possible to install both software and hardware firewalls in your network.

Advantages

• Offers all-round protection of your network and devices
• Difficult for attackers to tamper with physical devices
• Better controls

Limitations

• Installation can be tough
• Requires regular maintenance
• High setup and maintenance investments 

Use Cases

Hardware firewalls are more suitable for medium to enterprise-level businesses. They have the infrastructure, budget, and workforce to set up, manage, and maintain hardware firewalls.

Provider: Palo Alto Networks

Cloud Firewalls

A Cloud-based firewall is hosted in the cloud. The service provider delivers this type of firewall to users in the form of a subscription-based service. This is why it’s also called Firewall-as-a-Service (FWaaS).

With a cloud firewall, you can centrally configure, manage, and maintain security policies across your organizational network, users, and systems. It enables you to add more features to the cloud server in order to filter heavier traffic loads.

You can get your cloud-based firewall from a recognized managed security service provider (MSSP). They host the firewalls in the cloud and distribute them to you for direct use. You can also configure the hosted firewall service to track the network activities of your internal team as well as third parties on demand.

Unlike traditional firewalls, cloud firewalls perform traffic and data packets at the cloud level. This helps minimize online threats and protect your sensitive data.

Advantages

• Easy to use
• Scalable with your organization’s demands
• No need to manage, configure, or maintain anything
• Protection for remote workers
• Cost-efficient than on-premise solutions

Limitations

• Complete reliability on the service provider for performance and service availability
• Offsite data processing can lead to privacy issues

Use Cases

All types of networks can use cloud-based firewalls. However, these are ideal for companies with multiple branches, remote employees spread across the world, and distributed networks. 

Small and medium-sized businesses can use it to avoid heavy costs and lower complexity in managing on-premise solutions.

Provider: Perimeter81, NordLayer

Web Application Firewall

Application firewalls and web application firewalls are effective at monitoring, detecting, and blocking harmful traffic, and keeping your network safe from intruders.

Application firewalls work with applications, services, and other software solutions in order to catch intrusion attempts that can leverage software vulnerabilities and pass through traditional firewalls. These firewalls can enable parental control to completely block access to some websites and apps.

Web application firewalls (WAF) are similar to application firewalls. The only difference is that web application firewalls only monitor web applications and not software installed on your computer. They can detect and block web apps like third-party apps carrying malware.

You can find many cloud-based WAFs if you don’t want to invest your time in setting, managing, and maintaining the firewall systems on your own.

Advantages

• Effortless to use
• Not easily vulnerable to security risks
• Enhanced protection for applications

Limitations

• Not compatible with every application
• Reduced performance on some apps

Use Cases

Any size and type of website or business can use WAFs.

Providers: Cloudflare, Sucuri

NAT Firewall

Network Access Translation (NAT) firewalls are the ones accessing the web traffic and blocking unwanted connections. NAT firewalls can hide a computer’s IP address in order to make the user anonymous and enforce greater security.

If several devices are connected to the internet, the firewall will create a fresh, unique, and single IP address. This IP address will be used for all those devices, while the actual IP address of the devices will be hidden.

This way, NAT firewalls provide safety to devices and data from attackers who are on the lookout for stealing IP addresses by scanning networks. Thus, by staying anonymous, your privacy and safety increases.

Advantages

• Keeps internal IP addresses private
• Can connect with a lot of hosts
• Improved performance and speed

Limitations

• Network complexity increases due to an additional layer of security
• Some applications won’t function with a NAT firewall

Use Cases

NAT firewall is best for organizations using several devices but requiring just one IP address for all. It helps them translate their unique IP addresses onto the public.

Host-Based Firewalls

Host-based firewalls are applications that you can install on devices like computers, laptops, servers, etc. These firewalls can filter traffic on each device based on certain rules that you have set on a given device.

Thus, you can set required rules on different devices and let the firewall protect it based on those rules. This way, you will get a granular control on each device.

Advantages

• Better protection and control for each device
• Efficient at blocking external and internal threats
• Remote security

Limitations

• Complex to maintain and manage at scale
• Impact on system performance

Use Cases

Host-based firewalls are great for smaller businesses and individuals who need enhanced security for their devices, especially from insider threats.

Providers: Microsoft Defender, Comodo

UTM Firewalls

Unified Threat Management (UTM) is a specialized tool with advanced features combining stateful inspection, antivirus, and intrusion prevention. It can also include more capabilities like cloud management, centralized controls, etc.

Advantages

• Easy to use
• Simple applications
• Advanced security features

Limitations

• Reduced system performance for a larger number of applications
• Settings might not be that powerful

Providers: Cisco Meraki, WatchGuard

Conclusion: What’s the Best Firewall?

Firewalls can secure your network from internal and external threats and are of various types. So, when deciding the best firewall type for your business or individual devices, think about your needs, business size, the industry you belong to, and the cost.

It’s always the best practice to combine multiple firewalls to enable multi-layer protection of your systems, devices, data, and network from different kinds of attacks, both internal and external. For example, you can see a cloud firewall at the network perimeter and a software firewall on each network device.

Next, you may also explore best personal firewalls for computer and mobile phones.