The importance of the firewall.

What is a firewall and why it’s important?

A firewall is a device or system that inspects all data going in and out of your network. Based on pre-configured rules, it either allows the data to pass or blocks it. Firewalls need to balance effectiveness with practicality, but they remain one of the key lines of cybersecurity defense.

Firewalls come in three types. A hardware firewall is a physical device that lies between your network and the rest of the internet. A software firewall is an application on your computer or server that performs the same functions. The newest type, “firewall as a service”, operates on a remote server: all your internet traffic goes through this tool either as the first step on its way out or the last step on its way in.

In all three cases, the basic functions and concepts are the same. Think of an old-style fort or castle where walls and moats mean the only way in or out is through a single gate. A gatekeeper vets everyone coming in and keeps an eye on people leaving, for example, to catch somebody trying to smuggle out stolen material. A computer firewall performs the same functions with packets of data rather than people.

Whether a firewall lets data in or out depends on a series of pre-configured rules. These vary greatly in detail and sophistication. One common approach is looking at the origin (inbound) or destination (outbound) of the data, for example, the IP address. Some systems work by blocking specific addresses that are suspicious or known to be threats. Other systems work by blocking all traffic unless it is going to or coming from a trusted source.

More sophisticated firewalls can run through a detailed checklist to assess the likelihood of a threat based on multiple factors, which can be updated based on the latest cybersecurity research. Some firewalls will even examine the content of the data to inform their assessment.

Another factor is ports. Our previous analogy of the single-door castle wasn’t entirely accurate as computer networks use virtual connection points known as ports, each of which covers data and communications transmitted for a specific purpose. (These aren’t the same as physical ports such as USB or HDMI.)

To extend the analogy, it’s a little like the castle having one door for delivering mail and another for delivering food supplies. Most firewalls will control the flow of data on a port-by-port basis, usually blocking each port unless there’s a genuine need and reason to use it.

The goal with any firewall setup is to maximize protection while minimizing disruption, either by slowing down data or blocking legitimate transfers. The best firewalls achieve this balance through flexible but intuitive controls.

To find out more about how firewalls can protect your business and which setup is best for you, contact CPI Solutions today.

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