What is a firewall?

For modern digital security, a firewall refers to a security system that monitors and controls incoming and outgoing network traffic based on predefined rules. Think of it as a digital gatekeeper: it decides which data packets are allowed to enter or leave your network, protecting systems from unauthorized access and cyber threats.

How a firewall works

Firewalls inspect network traffic and apply filtering rules. They can operate at different levels:

Packet filtering: Examines individual data packets for compliance with rules.
Stateful inspection: Tracks active connections and ensures packets belong to a valid session.
Application-level filtering: Monitors traffic for specific applications or protocols.
Next-generation firewalls (NGFW): Combine traditional filtering with advanced features like intrusion prevention and deep packet inspection.

Firewalls can be hardware-based, software-based, or cloud-delivered, depending on the organization’s needs.

Why firewalls are important

Firewalls are essential for:

Blocking unauthorized access: Prevent hackers from exploiting vulnerabilities.
Protecting sensitive data: Stop malicious traffic before it reaches internal systems.
Maintaining compliance: Many regulations require network security measures.
Reducing attack surface: Firewalls help isolate networks and segment traffic.

As cyberattacks grow more sophisticated, firewalls remain a critical layer in a multi-layered security strategy.

Common questions about firewalls

What’s the difference between a firewall and an antivirus?

A firewall controls network traffic; antivirus software detects and removes malicious files.

Do small businesses need firewalls?

Yes. Firewalls protect against common threats like malware and unauthorized access, regardless of business size.

Are firewalls enough to secure a network?

No. Firewalls are only one layer of defense. Organizations should also use encryption, authentication, and endpoint protection. And organizations with employees who work off-site, remotely or from home offices, need to ensure appropriate security measures are deployed to protect information.