What is a Firewall: A Guide to Safeguarding Computer Networks

Technological advancements and the constant sharing of data across organizations have made cybersecurity one of the most critical risks for enterprises globally. According to a cybersecurity report by Allianz Commercial, ransomware attacks increased globally by 143% in the first quarter of 2023. The report also predicts that cybersecurity victims will incur a $265 billion annual cost by 2031. Attackers today use automated tools to launch bulk cyberattacks, making it difficult for organizations to prevent cyberattacks. Therefore, the most recommended method to mitigate cybersecurity risks is early detection and quick response. Hence, organizations are integrating firewalls for network security. This is expected to result in an 18.9% annual growth of the firewall market by 2027. Let’s understand what is a firewall, its purpose, types, and advantages.

What is a Firewall and What is its Purpose?

These are network devices or tools that monitor and restrict unauthorized traffic within a private network, thus enhancing network security. The answer to what is a firewall can be understood easily from its name. The term has its origins in physical construction and was first used in the 1760s. It means a wall or structure that separates the parts of the building vulnerable to fire from the other parts. It acts as a physical barrier to prevent damage. Similarly, in a computer network, it is a hardware or software security system whose purpose is to monitor Internet traffic within a network and block threats by preventing network access to unauthorized users. The most significant uses of this network are:

• Preventing external cyberattacks by blocking unauthorized traffic
• Logging data or events that help in cybersecurity audits and enables professionals to identify attack patterns
• Restricting access to networks where confidential data is stored
• Preventing users from accessing objectionable websites

ALSO READ: What is a Human Firewall: Why is it Important and How to Use it

How Does a Firewall Protect a Computer Network?

Now that you know what is a firewall, let’s understand in detail how does a firewall work to protect a computer network. It acts as a barrier at the entry point of a network. A firewall examines all the traffic that goes through a network at the entry point and filters or blocks unnecessary traffic through suspicious IP addresses based on the organization’s policies. Here is the detailed role of a firewall in safeguarding a computer network:

1. Internal Policies 

How does a firewall work? It blocks or allows traffic within a network according to two internal policies—deny and allow policies. In the default deny policy, the firewall administrator creates a list of network services that are authorized access. It blocks the rest of the network services. The allow policy works vice versa. The administrator creates a list of networks that are not allowed to access the system. It allows traffic through all other network services.

2. Firewall Components

This technology architecture comprises the following key components:

• Packet filtering uses a router to verify IP packets based on the IP address
• Application gateways act as a proxy server and prevent direct contact with the main server
• Network Address Transformation (NAT) converts a private IP address to a public IP address within a local network 

What are the Different Types of Firewalls?

The following are the most common types of firewall used to prevent cybersecurity attacks.

1. Packet-Filtering Firewall

This is the most basic type of firewall in which the packet filter monitors traffic in the form of single packets, applies configured rules as per internal policies, and allows or blocks the network device accordingly. These firewalls have limited capacity and cannot monitor each packet during traffic overflow.

2. Stateful Inspection Firewall

It is called a dynamic packet-filtering firewall because it offers packet inspection technology along with Transmission Control Protocol (TCP) handshake verification. The stateful inspection firewall also checks the transactions and established connections. It creates a repository of source IP address, destination IP, and port data.

3. Circuit-Level Gateway

The circuit-level gateway offers User Datagram Protocol (UDP) and TCP connection security. It monitors active sessions according to the rules established by the network administrator. However, it doesn’t analyze the contents of the packets.

4. Next-Generation Firewall (NGFW)

This type of firewall uses advanced technologies like Deep Packet Inspection (DPI) and Intrusion Prevention Systems (IPS) in addition to the features of traditional firewalls. Moreover, they include additional layers for filtering packets.

ALSO READ: Cybersecurity for Beginners: Learn How to Secure Your Data

What are the Advantages of Using a Firewall?

The following are the key advantages of firewall for computer networks:

1. Threat Protection

Protecting a computer system against cybersecurity attacks is one of the most significant advantages of firewalls. They act as the first line of defense by blocking unauthorized users.

2. Prevents Cybersecurity Losses

According to IBM’s Data Breach Report 2023, the average cost of a data breach was $4.45 million. Since firewalls protect computer networks from cyberattacks, they help organizations reduce cybersecurity losses.

3. Enhances Regulatory Compliance 

Many jurisdictions impose strict data privacy and security liabilities on organizations related to customer data. Hence, organizations need to implement effective cybersecurity policies and tools. Firewall acts as the primary source of data protection. Therefore, it ensures regulatory compliance.

4. Aligns Security Policies With Business Needs

Modern firewalls are more advanced in comparison to the traditional ones. One of the best advantages of firewalls is that they deny or allow access on the basis of user identity instead of solely depending on IP addresses that are easily imitated by hackers.

How Can Firewalls Enhance Network Security?

A detailed explanation of what is a firewall and how does a firewall works shows that they can enhance network security by monitoring incoming and outgoing traffic. They block unauthorized network devices and prevent intrusion. This allows only trusted devices to access an organization’s confidential data. Simply put, various types of firewall act as a barrier between the internal network and the external network, allowing organizations to safely connect to the Internet without the risk of their data getting hacked or leaked. Therefore, firewalls enhance network security.

Can Firewalls Prevent All Types of Cyberthreats?

Even though firewalls act as a shield for the internal information security network, they have certain limitations. Hackers can breach firewalls using techniques like IP address spoofing or source routing attacks. Moreover, firewall operating systems often have vulnerabilities that hackers can exploit by installing malware into the system.

An overview of what is a firewall explains that firewalls mainly protect computer networks from cyberattacks that occur over the Internet. However, they can’t prevent internal cyberattacks, such as deleting a file infected with malware. Furthermore, firewalls cannot protect organizations against data leakage through hardware. Hence, firewalls cannot prevent all types of cyberthreats. Therefore, organizations need additional tools and information security technologies along with firewalls to strengthen the security of their computer networks.

ALSO READ: Cybersecurity Risk Management: Top 5 Ways to Mitigate Potential Threats

There has been a massive increase in cybersecurity investments globally. Organizations are not only seeking advanced tools but also talented resources to mitigate cybersecurity risks. However, hackers are constantly using advanced methods and technologies to breach security systems. Therefore, professionals need to stay updated with the latest cybersecurity trends to build a successful career in this field. Pursuing online cybersecurity courses is one of the best ways to become a cybersecurity expert. They teach you what is a firewall, its essential components, and its functions. Moreover, the courses also help you learn advanced skills and concepts related to cybersecurity from industry experts. Explore Emeritus’ online cybersecurity courses to enhance your career!

Write to us at content@emeritus.org