Firewall: Overcoming walls

A program must always open a 'port' - or at least a porthole - if its generated content is also to be visible on other monitors worldwide. As in the case of a homepage, for example. Where something can leave such a 'port' or 'harbor' into the virtual world, something can of course also enter it. This is why 'firewalls' were created to protect a computer from unwanted access from the network. These security programs make sure that only the desired guests enter the home port according to defined rules. As a rule, every access must overcome two such protective walls: the first at the provider, the second at the client on the network computer.