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The firewall is a system that contains both software and hardware elements. Its purpose is to securely connect IP networks and protect them from unwanted network access.

You can think of the firewall as a gatekeeper who controls what data wants to enter the building and what data wants to leave. The gatekeeper checks which data is authorised and which is unauthorised. Protection is provided by the security gateway between the internet and the intranet and also between two internal organisational networks. For example, the personnel department of the sales department.

In connection with the use of private computers, everyone has certainly heard of the term firewall. Here the firewall is an independently running system on the computer, which is also called a personal firewall (PFW). The PFW protects the computer from external attacks and prevents malware from making contact. For the implementation of the protection, all data that reach the computer are controlled as well as all connections to other networks and requests to the Internet.

But what is the benefit of a firewall for a company?

A protected connection to the internet is even more important on company computers than on private computers. In addition to the work that the firewall also does on private computers, it helps the company not to have to protect every single computer, but only the devices that are connected to an external network. In addition to computers, other devices connected to the company network should also be protected and controlled by the firewall, such as copiers, printers and multifunction devices. For this purpose, the administrator of the firewall – an employee from IT – creates lists, which contain permitted senders, about what data is allowed past the gatekeeper. The passing of permitted communication is called whitelisting.

Typically, the firewall in the company functions as a packet filter. This means that it inspects the data packets at different ISO/OSI levels and assigns them to different filter targets based on criteria.

The General Data Protection Regulation requires companies to implement suitable technical and organisational measures (TOM) to protect data. In data processing agreements (DPAs), the use of a firewall has also become a standard requirement, as it serves as a measure to realise the protection goal of availability.

In order to check whether possible attacks have occurred, i.e. whether unauthorised persons have tried to access the computer, the log files of the firewall should be viewed.  If these are not continuously monitored, in the worst case attackers remain unnoticed and penetrate the internal network in a damaging way.