What Is a Firewall?

Key takeaways

• A firewall is a network security device that acts as a gatekeeper, controlling the incoming and outgoing internet traffic on your private network.

• Firewall software is installed on individual devices to prevent malicious traffic, making it a popular firewall option for individuals and small businesses.

• A firewall in a computer network creates a barrier between trusted and untrusted networks based on a predetermined set of security rules.

The primary function of a firewall is to provide network security. Explore what a firewall is and some common types of firewalls below.

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What is a firewall?

A firewall is a network security device. It creates a barrier between a trusted network and an untrustworthy network. For example, a firewall can restrict internet traffic from accessing your private network. It acts like a gatekeeper, controlling incoming and outgoing traffic according to a predetermined set of security rules.

Types of firewalls

The list below outlines a few examples of firewall types:

• Hardware firewall: Also known as an appliance firewall, this type of firewall is a separate, self-contained piece of hardware designed to filter network traffic. Hardware firewalls are popular among larger organizations with many computers in their network.

• Software firewall: Software firewalls are installed on a host device to prevent malicious traffic. To provide protection to several computers, a version of the software must be installed on each one. For this reason, software firewalls are popular among individuals and small businesses.

• Application firewall: This type of firewall is designed to control outgoing and incoming traffic and provide protection at the application layer. Examples include web application firewalls (WAF), which protect web servers and sites, and database firewalls (DB).

• Network firewall: Network-based firewalls monitor incoming and outgoing traffic from the internet to secure local area networks (LANs). They prevent security issues like malware threats from impacting the entire network by blocking unauthorized access to all connected devices.

Firewall vs. antivirus: What's the difference?

Antivirus is security software. A firewall can be hardware, software, or a combination of the two. Firewalls focus on preventing unauthorized access and monitoring network traffic. The primary goal of antivirus software is to prevent, monitor, and eliminate harmful code or software.

Read more: Cybersecurity Glossary: Key Terms & Definitions

Related terms

• InfoSec

• Cybersecurity

• Security engineer

• Social engineering

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