Skip to main content

What are the Types of Firewalls?

The word "firewall" was first used to describe the process of screening undesirable network traffic. The name was a play on words, comparing the device to fire partitions that prevent a fire from spreading from one portion of a building to another. In the case of networking, a firewall is a network security solution that monitors both incoming and outgoing network traffic to detect and prevent suspicious packets based on security policies and allows only legitimate traffic into the private network. It is typically your first line of defense against cyber threats such as malware, viruses, and hackers attempting to gain access to your organization's valuable assets.

Firewall architectures have evolved dramatically over the last quarter-century, from first-generation and stateless firewalls to next-generation firewalls. Both the firewall's capabilities and deployment options have improved as a result of recent advances. You can now protect your network infrastructure with a variety of firewall types, including proxy firewalls, stateful inspection firewalls, and UTM firewalls, and can even use multiple types concurrently for an additional security layer, defense-in-depth solution.

There are several methods for configuring a firewall. The type of firewall and how it is set to have an impact on the level of protection they give.

Today, firewall technology provides three deployment methods. Firewalls can now be deployed as a hardware appliance, as software, or as a service(Cloud). Therefore, firewalls can be classified as follows based on their deployment methods:

  1. Hardware Firewalls
  2. Software Firewalls
  3. Cloud Firewalls

Firewalls are also classified according to how they work, and each type can be deployed as software or as a hardware device. There are six basic types of firewalls, each with its mode of operation:

  1. Packet Filtering Firewalls

  2. Proxy Firewalls

  3. Next-Generation Firewalls

    3.1. Threat-Focused NGFW

  4. Stateful inspection firewalls

  5. Circuit-level Gateways

  6. Unified Threat Management (UTM) Firewalls

    What are the Types of Firewalls

Figure 1. What are the Types of Firewalls?

In this article, we'll cover the types of firewalls, their differences, how each type can protect your network in different ways, the advantages and disadvantages of firewalls, risks of not having any firewalls, and the weakness of firewalls.

1. Hardware Firewalls

Hardware firewalls, also known as network-based firewalls, are physical devices that each have their own processing power. They serve as a barrier between the trusted internal networks and the untrusted external networks, such as the internet, filtering out network packets and traffic requests from untrusted sources. Hardware firewalls are useful for businesses with a large number of devices. They can be deployed not only as an external firewall but also as an internal firewall to prevent insider attacks. Although they are beneficial for network segmentation to protect valuable assets, they can not provide comprehensive endpoint security since they don't inspect and filter the traffic between the endpoints in the same network segment. As a result, a combination of software and hardware firewalls is strongly recommended for optimal network security, particularly in business networks. Furthermore, the capabilities of a hardware firewall may differ depending on the manufacturer. For example, some may have a lower ability to handle simultaneous connections than others.

2. Software Firewalls

Software firewalls also called host-based firewalls, are deployed independently on each device. They offer more fine-grained control by allowing access to one application while denying access to others. A software firewall's main advantage is that it may be used to create defense in depth by separating individual network endpoints from one another. However, because they use the hardware resources of the devices they are running on, such as CPU and RAM, they can be resource-intensive. Another disadvantage of software firewalls is that they are difficult to manage especially in large organizations since administrators must configure and maintain them separately for each device. Furthermore, all devices may not be compatible with a single software firewall, necessitating the use of several firewalls.

3. Cloud Firewalls

Cloud-based firewalls, also known as firewall as a service(FaaS), are available from managed security service providers (MSSPs). Many people confuse cloud firewalls with proxy firewalls since a cloud server is regularly used in proxy firewall configurations. This hosted service can be set up to monitor both internal network traffic and third-party on-demand environments. Cloud-based firewalls can be completely managed by an MSSP, making them an attractive option for large or widely dispersed enterprises with security resource gaps. Scalability is the most significant benefit of cloud firewalls. The cloud firewall capacity can be expanded to filter greater traffic volumes as the demands increase. They may quickly expand to suit the organization's traffic requirements. If demand grows, the cloud server's capacity can be increased to filter out the additional traffic. Like physical firewalls, cloud firewalls excel at perimeter security. They are commonly used to secure internal networks or entire cloud infrastructures. Another benefit of cloud firewalls is that they are cost-effective in terms of equipment management and maintenance. However, depending on the services provided, there is a wide range of pricing. The potential of losing control of security assets is another disadvantage. Migrating to a new cloud provider may also cause compatibility issues.

4. Packet-Filtering Firewalls

The first and simplest type of firewall is a packet filtering firewall. They simply verify a data packet's source and destination IP addresses, protocol, source/destination port against specified rules at the network layer to determine whether to allow or deny it. Packet filtering firewalls are fundamentally stateless which means that they monitor each packet separately without keeping account of the established connection or the packets that have previously passed through it. As a result, these firewalls' ability to protect against advanced threats and attacks is severely constrained.

The main advantages of packet filtering firewalls are that they are quick, inexpensive, and effective. However, the security they give is rudimentary. They are unable to guard against malicious data packets arriving from trusted source IPs because they cannot inspect the content of the data packets. They're also subject to source routing and tiny fragmentation attacks because they're stateless. Another downside of packet filtering firewalls is the difficulty in setting up and managing access control lists. Despite their limitations, packet filtering firewalls paved the way for current firewalls that provide better and deeper security.

5. Proxy Firewalls

Proxy firewalls, also known as application-level gateways, are implemented using a proxy server at the application layer. The connection is created through the proxy firewall rather than an outsider directly accessing the internal network. First, the proxy firewall receives a request from the external client. Then, the proxy firewall verifies the request's authenticity before forwarding it to one of the internal devices on behalf of the client. An internal client can also request access to a website, and the proxy device will send the request while concealing the identity and location of the client. As a result, one of the main benefits of proxy firewalls is providing privacy.

Proxy firewalls assess the context and content of data packets against a set of predefined criteria using stateful and deep packet inspection. They either allow or reject a packet based on the results. They restrict a direct connection between internal and external networks, protecting the identity and location of your important resources. However, setting them for effective network security can be difficult. Another drawback of proxy firewalls is that they may cause significant delays since they act as an additional barrier between client and server. Also, they don't support all network protocols. Finally, they necessitate a significant amount of effort to reap the greatest benefit from the gateway.

6. Next-Generation Firewalls

According to Gartner, a next-generation firewall is "a deep-packet inspection firewall that moves beyond port/protocol inspection and blocking to add application-level inspection, intrusion prevention and bringing intelligence from outside the firewall". They address the shortcomings of classic firewalls while also providing extra security measures.

Next-generation firewalls are more durable and provide a broader and deeper level of protection than their predecessors without slowing down the network. They have an application awareness capability for intelligent traffic and resource analysis, in addition to performing deep packet inspections to detect malware and other anomalies. These firewalls are capable of stopping DDoS attacks in their entirety. They provide decryption functionality for Secure Sockets Layer (SSL) to acquire total visibility across applications, allowing them to detect and prevent data breach threats from encrypted applications as well.

Another advantage of NGFWs is that they can incorporate other security solutions, like intrusion-prevention systems (IPS) and anti-virus, to provide more comprehensive network security. Also, users and user groups can be identified by next-generation firewalls. This ground-breaking feature allows users to use WiFi and mobile devices while maintaining wider security in dynamic workplaces with BYOD regulations.

The most significant downside of NGFWs is that they are more expensive than other types of firewalls, and depending on the firewall, security administrators may need to interface them with other security systems which can be a difficult process.

6.1 Threat-Focused NGFW

All of the features of a regular NGFW are present in a threat-focused NGFW. They also offer advanced threat detection and mitigation services. These firewalls are capable of responding quickly to attacks. Threat-focused NGFW employs intelligent security automation to set security rules and policies, enhancing the overall defensive system's security.

Furthermore, these firewalls employ retrospective security measures to continuously detect suspicious activity. They continue to evaluate the behavior of each action even after the initial assessment. Threat-focus NGFW significantly decreases the time it takes from threat detection to threat cleanup as a result of this feature.

7. Stateful inspection firewalls

Stateful inspection firewalls perform packet inspection in addition to confirming and tracking established connections to give stronger and more complete security. Once a connection is established, they create a state table comprising the source/destination IP addresses, source/destination ports. Instead of depending on a hardcoded set of rules based on this knowledge, they develop their own rules dynamically to enable predicted incoming network traffic. Data packets that do not belong to a verified active connection are conveniently denied. Stateful firewalls have extensive logging capabilities that can be used for troubleshooting and monitoring.

To determine which data packets can get through, stateful inspection firewalls look for genuine connections as well as source and destination IP addresses. Although these additional checks provide enhanced security, they require a significant amount of system resources and may significantly reduce speed. As a result, they are vulnerable to DDoS attacks. Other drawbacks of the stateful firewalls are that they are more expensive than some of the other firewalls and they don't offer an authentication mechanism to ensure that traffic sources are not spoofed.

8. Circuit-level Gateways

Circuit-level gateways work at the session layer, verifying established Transmission Control Protocol (TCP) connections and keeping track of current sessions. They're comparable to packet filtering firewalls in that they only execute one check and use a small number of resources. They work at a higher level of the Open Systems Interconnection (OSI) model, though. They are mainly responsible for determining the safety of an established connection. When an internal device connects to a distant host, circuit-level gateways create a virtual connection on the internal device's behalf to hide the internal user's identity and IP address.

Circuit-level gateways provide several advantages, including minimal cost, easy to install and manage, and little influence on network performance, only processing the requested transactions by rejecting all other traffic. Their inability to inspect the content of data packets, on the other hand, renders them an insufficient security mechanism on their own. If a data packet contains malware and has a valid TCP handshake, it can easily circumvent a circuit-level gateway. For enhanced security, another sort of firewall should be deployed on top of circuit-level gateways. Also, they can not provide application-layer security. Finally, they require regular changes to maintain the regulations up to date.

9. Unified Threat Management (UTM) Firewalls

Unified threat management (UTM) appliances, which come in the form of a single box that plugs into the network, offer a nearly complete security solution for small and medium-sized businesses. Typical UTM features include a traditional firewall, an intrusion detection system(IDS), and they occasionally include next-generation firewall (NGFW) and web application firewall features. These firewalls are created with simplicity and ease of use in mind. Many more services, such as cloud management, can be added to these firewalls. Most UTMs are effective at safeguarding a network, however, optimal solutions for every security function will almost certainly provide greater security.

How to Choose a Firewall?

The budget that the company has for information security, the assets that need to be protected by the firewall, and the infrastructure architecture are all part of identifying the suitable type of firewall. The finest firewall for one company might not be the best firewall for another.

The following are some things to think about when choosing a firewall:

  • What are the firewall's technical objectives?
  • What is the size of the internal network?
  • Is it necessary to have a firewall that monitors the internal network, or can you manage a firewall on each device? When picking between software and hardware firewalls, several considerations must be addressed. Furthermore, the ability of the technical staff assigned to handle the setup will play a big role in deciding between the two.
  • What role does the firewall play in the overall architecture of the company? Consider whether the firewall is designed to safeguard a trending web application or a poor service accessible on the internet.
  • Do you have enough budget to separate the firewall from the internal network by using another hardware or even the cloud? The amount of traffic that the firewall must filter, as well as whether or not it will be consistent, are both essential considerations.
  • What is the required protection level? The number and types of firewalls should correspond to the level of security required by the internal network. A company that deals with sensitive client information should strengthen its firewall protection to keep data safe from hackers.
  • What types of traffic inspections are required? Some applications may demand that entire packet contents be monitored, while others can merely sort packets by source/destination addresses and ports.

Understanding the architecture and operations of the internal network being secured is the first step in selecting the best firewall, but it also necessitates knowledge of the various types of firewalls and firewall policies that are most successful for the enterprise.

No single security layer, no matter how strong, will ever be adequate to keep your company safe. Your networks should have multiple levels of firewalls, both at the perimeter and isolating distinct assets on your network, to provide better protection. For example, at the perimeter of your network, you may have a hardware or cloud firewall, and then individual software firewalls on each of your network assets.

Additional firewalls serve to make your network more difficult to break into by providing additional defense-in-depth by isolating distinct assets, making it more difficult for attackers to access all of your most critical data.

The firewalls you choose will be determined by the capabilities of your network, industry-specific compliance needs, your budget, and the resources available to manage these firewalls.

Whatever kinds of firewalls you employ, keep in mind that a poorly designed firewall might be worse than having none at all because it creates a dangerously false sense of security while delivering little to no defense.

Which Firewall Architecture is Right for Your Business?

There is no need to be explicit when it comes to choosing the ideal firewall design. There is no single solution that can meet each company's specific security needs. In truth, each sort of firewall has its own set of advantages and disadvantages. For instance, proxy and stateful inspection firewalls can degrade network performance, while packet filtering firewalls are simple but offer limited protection. Although next-generation firewalls appear to be a complete solution, not every company has the funds or resources to adequately deploy and administer them.

Organizations' security measures must keep up as cyber threats get increasingly complex. Data breaches in the previous ten years have demonstrated that a single firewall is insufficient to secure the perimeter of an internal network from external attackers. Each asset in the local network requires its level of protection. Instead of trusting in the capability of a single firewall, it is essential to use a defense-in-depth approach for stronger security. Why settle for only one firewall when you can take advantage of the benefits of many firewalls in a security architecture tailored to your company's needs?

Some of the useful tips for selecting the right firewall for your business are explained below.

Hardware firewalls are ideal for medium and large companies that need to protect a large number of devices. Hardware-based firewalls are more difficult to configure and manage than host-based firewalls.

Cloud-based firewalls are beneficial for smaller organizations with fewer resources and expertise.

Although packet filtering may not provide the level of security necessary in every situation, there are occasions when this low-cost firewall is a great alternative. Packet filtering is a minimum level of security that can guard against known threats for small or budget-constrained enterprises. Packet filtering can also be used as part of the layered defense to filter potentially hazardous communication between internal departments in larger companies.

While circuit-level gateways are more secure than packet-filtering firewalls, they should be used in conjunction with other security solutions. Circuit-level gateways, for example, are frequently used in conjunction with proxy firewalls. This methodology incorporates packet-level and circuit-level gateway firewall characteristics with content filtering.

Proxy firewalls are best suited for defending enterprise resources against web application threats. They can both block access to malicious websites and prevent private information from being leaked from within the firewall. They're commonly used by Internet users to maintain network anonymity and circumvent online limitations especially imposed by governments or organizations.

Organizations who need to comply with the Health Insurance Portability and Accountability Act (HIPAA) or payment card industry (PCI) requirements, or those that want various security features integrated into a single system, should use next-generation firewalls. These firewalls provide the multifunctional capability, which appeals to those who understand how dangerous the threat environment is. NGFWs perform best when combined with other security systems, which in many cases necessitates a high level of expertise.

What are the Advantages of Firewall?

A firewall lies at the edge of a secured network, and all traffic passing through it is routed via it. This gives it insights into these traffic flows and the ability to block any traffic that violates the network's established access control lists (ACLs) or is otherwise regarded a danger.

A firewall is crucial because it serves as the first line of defense for a network. A good firewall can detect and block a wide range of threats, stopping them from gaining access to the internal network. This reduces the quantity of dangerous traffic that other security systems should check, as well as the internal network's potential risks.

Advantages of firewall are as follows:

  • Network Monitoring and Analyse: A network firewall monitors and analyzes traffic by determining whether or not the traffic or packets passing through the network are safe. As a result, it retains network security from malicious content that could harm it.

  • Provides Defense-in-Depth: Firewalls can also provide defense in depth for attacks that manage to penetrate the network boundary. An enterprise can get greater insight into internal traffic and make it even harder for an attacker or hostile insider to move laterally within the network by deploying network firewalls to segregate the network. A next-generation firewall placed inside the business network benefits from application management and identity-based inspection in addition to the fundamental threat prevention features. Application control allows a firewall to determine which application is responsible for a particular stream of network traffic. This enables the firewall to apply application-specific security regulations, lowering the risk of insecure apps and allowing the company to ban unauthorized applications from accessing their network. Identity-based inspection adds to the context of a network flow's examination. A firewall can impose access rules based on employee job roles and assigned permissions by identifying the user doing a certain action. Because privileged accounts are used in 74% of data breaches, monitoring, and control of the actions taken by these identities is critical.

  • Stops Hacking: In a world where everybody is connected to the Internet, it is more important than ever to keep firewalls in place and use the internet safely.

  • Stops Viruses: Viruses may infect your devices from anywhere, such as a spam email or an insecure website, making it even more vital to have a powerful security system, as a virus attack can easily shut down an entire network. A firewall is essential in such a situation. Threat prevention technologies such as intrusion prevention systems (IPS) or antivirus are now included in UTM (Unified Threat Management) devices and Next-Generation Firewalls to detect and block malware and threats. Sandboxing technologies may be included in these devices to detect risks in files.

  • Better Security: If we are monitoring and analyzing the network regularly and establishing a spam-free and malware-free environment, then a network firewall will provide better security for our network. Before an attempted attack enters the corporate network, a firewall with threat prevention capabilities can detect and block it. This greatly reduces the amount of harm that these attacks can inflict on the company, as well as the level of cyber risk that the firm and its personnel face.

  • More Privacy: By protecting the network and improving security, we get a more trustworthy network.Basic network services such as Virtual Private Network (VPN) and Network Address Translation (NAT) can also be performed by firewalls. Internal client or server IP addresses that are in a "private address range", are hidden or translated to a public IP address using Network Address Translation. Because the IP address of protected devices is hidden from the Internet, it protects against network reconnaissance. Similarly, a virtual private network (VPN) extends a private network across a public network through an encrypted tunnel, protecting the contents of packets as they travel across the Internet. This allows users to send and receive data over shared or public networks in a secure manner.

What are the Risks of not Having a Firewall?

While having a firewall does not guarantee that your valuable assets will be protected from all types of attacks, the implications of not having one are far more serious. The top dangers of not having a firewall are listed below:

  • Being publicly accessible without any restrictions: Without a firewall, it's the equivalent of leaving your front door wide open. Anyone may get access to a firm's network without a firewall, and the organization has no method of monitoring potential threats or suspicious activity.
  • Network Outage: Total network collapse is one of the scariest outcomes you might face if you don't have a firewall. Cybercriminals can effectively shut down your firm if you don't have appropriate security. And this can have disastrous consequences for your company. Not only might you lose data, but it could take days, if not weeks, to get your systems up and running again. According to research conducted by GE Digital's Vanson Bourne, unplanned downtime can cost a corporation more than $250,000 per hour on average. Some industries claimed an average cost per minute of more than $25,000 in some cases. When you include in lost production, morale, and consumer trust, it's just a matter of time until the consequences of downtime become irrevocable.

  • Data Access Without Restrictions: Anyone who can get into your corporate network has complete access to all of your data. It is a big mistake to think that your tiny business doesn't need to worry since the data it generates has no value outside of your company. Every data is important, and hackers are well aware of this. According to the Ponemon Institute, the average cost of a data breach is $4.24 million per event, up 10% over last year's $3.85 million. You allow attackers full reign over your data if you don't use a firewall. They have the option of stealing your data, leaking it to the public, encrypting it and holding it for ransom, or simply deleting it

  • Cyber Threats: Without a firewall, your valuable assets are unprotected against a lot of cyber threats listed below:

  • Intrusions
  • Malware & Spyware
  • Botnets attacks
  • Geo-IP attacks
  • Content-related attacks from the LAN (HTTP Proxy, Avoidance Systems)
  • Encrypted payloads such as Ransomware, Zero-Day attacks
  • Rogue Services within the network such as blocking outbound DNS except for Authorized servers
  • Flood attacks
  • PoD (Ping of Death) attacks.
  • TCP State Manipulation DoS
  • DoS (Denial of Service)
  • DNS Rebinding attacks
  • IP Spoofing attacks

What are the Threats of Firewalls?

Implementing firewalls as a proactive security measure keeps your company safe and competitive. Firewalls are used to defend network systems from threats as the first line of defense. They protect your environment by controlling entry points, monitoring efforts to get system access, blocking undesirable traffic, and preventing external dangers from entering.

You must not ignore firewall risks and vulnerabilities. Even if you monitor and perform penetration tests on a regular basis, blind spots can still exist. Security flaws might go overlooked for a long time. The following are some of the hazards to the efficiency of your firewalls that can be avoided.

  • Old firmware: As with any other piece of software, there are flaws that attackers can exploit. This is true of firewall applications as well. When firewall providers uncover these flaws, they normally work quickly to develop a patch that addresses the issue. However, some security teams are incredibly busy, and it's easy to fall behind on keeping firewalls up to date. The vulnerability will remain until the patch is applied to firewall firmware, waiting to be exploited by a random attacker. Poor patching routines may expose companies to firewall threats. The most effective solution to this problem is to establish and adhere to a disciplined patch management schedule. According to this plan, the cybersecurity team should check for all firewall software security updates and make sure to deploy them as soon as feasible.

  • Weak Password: Modern passwords can be difficult to remember due to character limitations. Some employees may use simple passwords or default factory settings for convenience. If this happens on your system, you're more susceptible to account invasion than you otherwise would be.

  • A Lack of Deep Packet Inspection: Before allowing or denying a request, less complex firewalls may simply check the data packet's place of origin and destination -information that an attacker might readily spoof to fool the firewall. The ideal solution for this problem is to employ a firewall that can perform deep packet inspection on data packets to detect known malware and reject it.
  • Mistakes in Configuration: Even if your network has a firewall and all of the newest vulnerability fixes installed, it might still cause issues if the firewall's configuration settings clash. In some circumstances, this can result in a decrease in network performance, while in others, a firewall may fail to provide adequate protection. A badly designed firewall makes things simpler for attackers while wasting time, money, and effort on your security measure.
  • Controls not Being Activated: Controls that aren't properly activated are one of the most typical firewall concerns that enterprises experience. Anti-spoofing tools, for example, are certainly part of your managed security system and are designed to keep malware, spam, and other false traffic at bay. If you don't enable this control, a distributed denial-of-service attack will almost certainly occur.

  • DDOS Attacks: DDoS (Distributed Denial of Service) attacks are a common attack tactic that is known for being both extremely effective and low-cost to perform. The main purpose is to overburden a defender's resources, causing a shutdown or protracted incapacity to provide services. Protocol attacks are one type of attack that aims to deplete the resources of firewalls and load balancers, preventing them from processing valid data. While firewalls can reduce some types of DDoS attacks, protocol attacks can still overwhelm them. There is no simple solution to DDoS attacks, as there are a variety of attack tactics that can exploit various flaws in network infrastructure. Some cybersecurity companies provide "scrubbing" services, which reroute incoming traffic away from your network and separate legitimate access attempts from DDoS traffic. This legal traffic is then forwarded to your network, allowing you to resume normal operations.

  • Lack of Documentation: Maintaining application documentation and rule decryptions can assist your company to avoid security gaps if any of your security personnel resign unexpectedly or are unavailable for an extended period of time. Proper documentation avoids work from being repeated, giving employees more time to concentrate on higher-level tasks.

  • Threats from Inside: Insiders are a hazard to the firewalls, even if they aren't the most likely of threats. An individual who has been given permission to bypass your perimeter firewall is the perpetrator of this typical firewall vulnerability. That person should have been given access to your internal systems as well. Employee threats can be mitigated with a solid network segmentation configuration technique.