What are the dangers of an open port? Whenever your computer connects to the Internet, such as to go to a website or to automatically detect and download updates, so-called ports come into play. Ports are similar to the house numbers of the addresses between which the connection exists and information packets are transmitted. If a port is open, you can access that open door of the digital house number and request services. For websites, certain open ports are intentional, so that site should be available at any time. For private or business devices, however, an unintentionally open port poses a danger: in the worst case, attackers can directly access the system. Firewalls block these unwanted gaps.