What Is a Network Firewall? (With Key Terms and Benefits)

By Indeed Editorial Team

Published April 9, 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.

By controlling your network traffic, a network firewall can help protect your computer and data. A network firewall is a security mechanism that determines whether incoming data from a network is valid for downloading or entering into a computer system. Understanding network firewalls can help you gain the skills necessary for a successful career in cybersecurity. In this article, we answer the question, "What is a network firewall?", share some key terms, provide a list of its benefits, review different types of firewalls, and explain how to install a network firewall.

What is a network firewall?

If you're interested in cybersecurity or want additional safeguards for your devices, you may be wondering, "What is a network firewall?" A firewall acts as a communications conduit between a network's internal and external devices. Individuals create a series of security policies defining what types of information are safe and unsafe for their computers to store. Network firewalls can also give remote access to a system by storing authentication information and providing a login portal. Firewalls enable users to access the resources they desire while keeping out unwanted users, hackers, viruses, worms, and malicious programs.

Related: How to Become a Network Engineer (With Job Role and Salaries)

Network firewall key terms

Here are some important terms related to network firewalls:

  • Virtual private network (VPN): The term VPN refers to a system that allows individuals to access the internet over a private network. A VPN ensures outside agents cannot learn the IP address of a computer.

  • Firewall zone: Firewall zones are virtual areas of a network containing specific information. Examples of firewall zones include the public internet, private networks, and demilitarized zones (DMZ), which provide access to both a private network and the internet.

  • Internet protocol (IP) address: The term IP address refers to a unique sequence of numbers that identifies hardware devices connected to a local network or the internet. All computer systems have IP addresses.

  • Network packet: Cybersecurity professionals use the term network packet to describe the data on a webpage, including its IP address. When you access information on the internet, your network exchanges packets.

  • Access control list (ACL): An access control list describes rules that firewalls use to determine whether they can send a packet of information to a computer system. Installing a firewall often involves the creation of an ACL list by security professionals and administrators.

  • Certificate: A digital certificate is an attachment to an electronic message that provides security features. A digital certificate can verify that the person sending the message is who they claim to be and encode a response from the receiver.

  • Common gateway interface (CGI): The CGI protocol allows web servers to pass control to an application upon user request. The application can then receive, organize, and return the information in a consistent format to the user.

  • File transfer protocol (FTP): The term FTP refers to a protocol for sending files across the Internet. FTP servers store files in directories and follow a hierarchy structure.

  • Transmission control protocol/IP (TCP/IP): The TCP/IP is a set of protocols that convert information into blocks of information called packets. The packets then travel over networks, such as the internet.

  • Intranets: Intranets are networks that provide similar services provided by the internet without an internet connection. As an example, a company may use one or more intranets on its internal TCP/IP network to share information between departments.

Related: Computer Literacy in the Workplace: What You Need to Know

Benefits of a network firewall

Using a network firewall can help you to:

Monitor network traffic

One of the major advantages of using a firewall is that it can measure and monitor traffic. Firewalls monitor network traffic by analyzing packets of information travelling through a network. If a firewall detects potentially harmful packets, it blocks them from entering the network immediately.

Related: What Is an Internal Analysis and How to Conduct One

Protect computers against viruses

A network firewall protects computing devices against unsafe programs and unauthorized files. Unapproved software or files activate the protection measures if they try to enter the network. The firewall stops and removes programs from delivering viruses that can infect the primary device, along with other devices on the same network.

Provide security from hackers

Hackers can perform malicious activities, such as spreading viruses on computers. A firewall verifies access by evaluating incoming traffic for malicious elements, such as hackers and malware, that may infect your computer. Network firewalls protect computers at their entry point by only allowing access from trusted sources and IP addresses.

Types of firewalls

Here are some common kinds of network firewalls:

Application-layer firewall

An application-layer firewall monitors communications over an external network by using an ACL to check incoming files for harmful data and ensures that computer programs only process verified files. Depending on the software, the application-layer firewall may delete data automatically or highlight possible threats for an individual to resolve manually. Security engineers can continually update the policies and protocols with an application-layer firewall to make it more secure. The firewall can also manage data between a network and a website-based application, such as an email account.

Packet-filtering firewall

Packet-filtering firewalls track and investigate packets to determine if they abide by the ACLs the network security engineer created. It reviews the system's IP address and confirms that a packet is safe to encounter. They also examine the embedded port number, which identifies the software program that transfers data between networks. The simple setup procedure enables easy installation and configuration of the packet-filtering firewalls for both cybersecurity professionals and personal users.

Next-generation firewalls

Next-generation firewalls can control the packet transmissions and VPN connections for a network. They operate similarly to traditional firewalls, but can also analyze each component of a website packet more thoroughly to prevent harmful materials from entering a computer system. This type of firewall can manage application data effectively by selecting which packets it accepts or rejects based on the source of each packet. A next-generation firewall may be helpful for network security professionals if a client stores a lot of confidential data.

How to install a network firewall

Here's how to install a firewall:

1. Choose a firewall program

Discover which firewall software is the most suitable for you and your computer by comparing various options. If you use website applications frequently, an application-layer firewall or a next-generation firewall may be beneficial. It may be helpful to use firewalls that can support VPNs to allow remote access to the network. Different systems allow users to connect a private network to public web structures.

2. Secure the firewall

A firewall's security is a key first step in ensuring that only recognized administrators can access the system and network. It's essential to restrict administrative access to your firewall to trusted individuals. For maximum defence, make sure you update your firewall to the latest vendor-recommended firmware, use complex passwords, and delete or rename default user accounts.

3. Establish firewall zones

To better prevent outside agents from accessing extensive databases, it may be beneficial to store them on internal firewall zones. A firewall zone can enhance network security by separating a network into different access protocols. As an example, a medical center that contains files with sensitive patient information may require additional security measures, such as a firewall zone.

4. Implement policies

Identify the most efficient method of configuring ACLs for each firewall zone. It's important to include all relevant information in an ACL, such as the description for each setting, access protocols for administrators, the IP addresses, and port numbers. Depending on the type of firewall, it may be helpful to specify that a network can only receive data if it's identified by the ACL. By using the ACL, you can also implement a policy that permits or denies traffic from specific websites and external networks.

5. Test the network firewall

A crucial step of successfully installing a firewall is to follow testing procedures that can ensure the firewall applies ACL rules properly and is operational. You may use a vulnerability scanning procedure that identifies potential breaches and generates a report for evaluating risks. Another option is a penetration test, which allows you to access a network manually through a hacking technique to see whether a firewall may block you.

Related: How to Become a Penetration Tester (Step-by-Step Guide)

6. Perform updates

Following the successful installation and testing of a firewall, you can begin managing it on a day-to-day basis. Check the firewall's activity history daily to verify that no unexpected events have occurred, and make sure all software components are up-to-date. Keeping track of ACLs every six months is also critical to ensure they remain relevant and useful. Documentation of management procedures may be helpful when updating ACLs and creating status reports.

Please note that none of the companies mentioned in this article are affiliated with Indeed.

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