What Is A Firewall? (With Benefits, Types And FAQ)

By Indeed Editorial Team

Updated 15 September 2022 | Published 28 April 2022

Updated 15 September 2022

Published 28 April 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Firewalls are essential for the security of a company's network because they prevent potential cyberattacks and information theft. One of the primary responsibilities of a cybersecurity professional is installing firewalls for a client or company based on the network requirement. By gaining fundamental knowledge about firewalls, you can ensure a secure network for a company and learn the skills required for a successful cybersecurity career. In this article, we answer “What is a firewall?”, explore the benefits of installing a firewall, discover its types and understand how it works.

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What Is A Firewall?

The answer to the question, “What is a firewall?” is that a firewall is a network security system that tracks every incoming data from a network to a computer device. A firewall monitors network traffic based on a few set rules to determine if the traffic is coming from suspicious sources. It can separate different network nodes to understand which nodes are meeting the specifications set by the network administrators.

A network node is a point of connection between different networks. This additional layer of security helps protect sensitive and private information from unauthorised personnel. It helps block malicious traffic, such as viruses that can steal information or harm the computer or hackers who can gain unsolicited entry into a network system.

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What Are The Benefits Of A Firewall?

Here are some benefits of using a firewall:

  • Protects critical information from viruses and malware: Malware and viruses can steal information and gain access to a computer network without having authorisation. The ability to use and install a firewall can help identify malware before they harm the computer.

  • Protects the network from external activities: A network firewall protects a computer from cybercriminals who attempt to steal information or data. It prevents people outside the workplace to gain access to a company's network.

  • Maintains network's storage capacity: New generation firewalls allow a computer network to create connections on the cloud storage. Also, they prevent outsiders and unauthorised personnel from gaining access to cloud storage.

  • Monitors network traffic: A firewall enhances a company's ability to monitor traffic that flows to a website or network. They leverage pre-established rules to protect the systems by analysing and monitoring traffic.

  • Promotes privacy: When companies proactively keep data safe, they build an environment of privacy that clients can trust. Also, upgraded data-protection systems provide a competitive edge to customers.

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How Does A Firewall Work?

A firewall works by carefully analysing every incoming traffic based on pre-established rules. Using these rules, they filter traffic from secured, unsecured and suspicious sources to prevent cyberattacks. They work by guarding traffic at a computer's entry point or ports. A firewall protects the port because it is where information exchange occurs with external devices.

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What Are The Different Types Of Firewalls?

If you are planning to become a cybersecurity professional or security engineer, you can benefit from knowing about the different types of firewalls. Here are a few common types of firewalls:

Packet-filtering firewalls

These are some of the oldest and most widely used firewalls. They work by checking the data packets that come through the router. The firewall helps inspect the packet type, destination, origination IP address, port number and other surface-level information without opening and analysing the packet's content. A packet-filtering firewall verifies whether a packet is safe to use. If not, it might be beneficial to drop all unsafe packets.

This type of firewall is not resource-intensive, and it does not significantly affect the system's performance. A cybersecurity professional can easily set up and configure the firewall. They do not check the packet's content or track them, so they are vulnerable to advanced cyberattacks.

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Software firewalls

A software or host firewall runs on a server, and a cybersecurity professional installs them in a device's software. They are easier to change and provide more control to the network administrator. Rather than installing them on a separate piece of hardware, professionals instal them on a local device. They can protect the system from any unauthorised access or malicious attack.

Maintaining individual software firewalls on different devices is time-consuming and different. Also, each device in a single network may require different setups and might not be compatible with the same firewall. As a result, a cybersecurity professional installs different firewalls for a single network.

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Hardware firewalls

A hardware firewall is a physical device that enforces a network boundary. The device uses its computing power to filter network access. Also, such physical devices can protect different devices on the same network, making it easier to manage larger networks. These devices can intercept malicious traffic from outside the network before the company's endpoints get exposed to unauthorised personnel. Even with so many advantages, it is easy for insider attacks to bypass them. As a result, an organisation using a hardware firewall may combine it with a software firewall to provide complete network security.

Also, the firewall's capabilities depend upon the manufacturer of the physical device because some firewalls may have a limited capacity to handle more than one connection at a time than others.

Proxy firewalls

A cybersecurity professional implements the proxy or application-level gateway firewall at the application layer using a proxy device. Instead of an outsider accessing the network directly, the firewall establishes a connection using a proxy device. The external client then sends a request to the proxy firewall and verifies the authenticity of the request. After completing the verification, a cybersecurity professional installs a firewall on the client's behalf. They perform deep packet inspection and analyse the packet's content against pre-defined rules.

Based on the inspection, they reject or permit a packet. Usually, a professional security system connects the firewall to one computer and allows other systems to use the IP address to access the Internet. Though this can reduce the network's speed, it successfully provides ample security for many people at the same time.

Circuit-level gateway firewalls

A circuit-level gateway primarily verifies the validity and authenticity of messages sent to a network through the Transmission Control Protocol (TCP). Every TCP has a distinct connection protocol, allowing a website to transmit packets. This firewall does not analyse or check the content of the TCP data packets. This means a circuit-level gateway might be vulnerable to complex and advanced cyberattacks. If the packet contains the malware and has the right TCP, the firewall accepts the packet into the company's network.

Usually, a cybersecurity professional installs a circuit-level gateway for clients who require a fast Internet connection to accomplish their work.

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Next-generation firewalls

The next-generation firewalls or NGFW are hardware devices that combine the latest firewall technologies with filtering functions like intrusion prevention (IPS) and deep packet inspection (DPI). Though they function as a traditional firewall, they analyse every data packet component. This ensures that harmful malware or virus does not enter the network or computer system. Also, its ability to manage application data more effectively differentiates NGFW from others.

NGFW can enhance the filtering of network packets. The firewall can reject or accept a data packet depending upon the location from where it comes. A cybersecurity professional installs an NGFW when a client stores a lot of confidential information in the system.

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Stateful inspection firewalls

A stateful inspection is an advanced version of a circuit-level firewall. It verifies and tracks connections to provide complete and comprehensive security. They create a table for recording destination IP, source IP, destination port and source port. After verification, the firewall sorts through connections established by network administrators. A firewall quickly drops connections they cannot verify.

Unlike others, a stateful inspection creates various dynamic rules that help filter the content of the data packet. These are more accurate and secure than most other firewalls. Also, they put a strain on the computing resources that can slow down the transferring speed of accepted and malware-free packets.

Network address translation (NAT) firewalls

A NAT allows multiple computer systems and devices with independent network addresses to connect with the Internet using only one IP address. They hide all the other IP addresses. So, when a cyberattack takes place, the attacker cannot capture specific details about the IP address. They provide greater security against attacks. They can accept or reject individual transmission using an implemented list of authorised network communications.

When a website tries to transmit an unknown file through a network, the NAT firewall can prevent downloading, and thus protect the computer and network. A NAT firewall is like a proxy server because it acts as an intermediary between different computers and website traffic.

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