A firewall is a security device computer hardware or software: that can help protect your network by filtering traffic and blocking outsiders from gaining unauthorized access to the private data on your computer.

Not only does a firewall block unwanted traffic, it can also help block malicious software from infecting your computer.

Firewalls can provide different levels of protection. The key is determining how much protection you need.

The topics below can help you learn what firewalls do and determine the level of protection that will help keep your computer and the data on it safe and secure.

What does a firewall do?

A firewall acts as a gatekeeper. It monitors attempts to gain access to your operating system and blocks unwanted traffic or unrecognized sources.

How does it do this? A firewall acts as a barrier or filter between your computer and another network such as the internet. You could think of a firewall as a traffic controller. It helps to protect your network and information by managing your network traffic. This includes blocking unsolicited incoming network traffic and validating access by assessing network traffic for anything malicious like hackers and malware.

Your operating system and your security software usually come with a pre-installed firewall. It’s a good idea to make sure those features are turned on. Also, check your security settings to be sure they are configured to run updates automatically.

How does a firewall work?

To start, a firewalled system analyzes network traffic based on rules. A firewall only welcomes those incoming connections that it has been configured to accept. It does this by allowing or blocking specific data packets — units of communication you send over digital networks — based on pre-established security rules.

A firewall works like a traffic guard at your computer’s entry point or port. Only trusted sources, or IP addresses, are allowed in. IP addresses are important because they identify a computer or source, just like your postal address identifies where you live.