A firewall is a network security system that monitors and filters incoming and outgoing network traffic based on predefined security rules and policies to protect against unauthorized access or malicious activity.

What is firewall?

Firewall it is a security technology designed to protect a computer network from unauthorized access. It monitors and filters network traffic based on predefined rules—allowing or blocking individual requests depending on whether they are considered safe. Firewalls can be software-based (installed on a device), hardware-based (standalone network equipment), or a combination of both as part of a comprehensive security solution.

How firewall appears in practice

Common use cases in companies:

• Blocking unauthorized access from the internet to internal company networks.
• Restricting access to inappropriate or unapproved websites.
• Enforcing network segmentation by limiting communication between departments.
• Detecting and blocking connections to risky or unknown IP addresses.
• Screening email attachments and content for malicious payloads.

A firewall essentially creates a secure perimeter around your digital assets—everything that doesn’t conform to policy stays out.

Firewall vs. related terms

• Firewall – filters network traffic based on pre-set rules.
• Antivirus – detects and removes malicious software from endpoints.
• Intrusion Detection System (IDS) – monitors the network for suspicious activity and alerts administrators.

Each tool addresses a different layer of cybersecurity: firewalls focus on perimeter defense, antivirus protects endpoints, and IDS provides visibility into network anomalies. Together, they form a layered defense strategy.

How to implement and maintain firewall in your company

Steps for effective firewall management:

1. Choose the right type of firewall for your company (software, hardware, or cloud-based).
2. Define clear access control rules – who can access what, from where, and when.
3. Segment your network into zones with different security levels.
4. Monitor firewall logs and regularly update rule sets.
5. Test firewall performance using simulated attacks or penetration testing.

Many companies install a firewall and leave it with factory settings—this creates a false sense of security. A firewall must be tailored to real business needs, continuously adjusted based on evolving threats, and actively monitored. Properly managed, it’s one of the most effective defenses in your security toolkit.