You already know that a firewall acts as a kind of barrier that checks what data can and cannot pass. This task can only be done through the establishment of policies, that is, rules, as you also know.
In a more restrictive way, a firewall can be configured to block any and all traffic on the computer or the network. The problem is that this condition isolates this computer or this network, so you can create a rule so that, for example, every application waits for authorization from the user or administrator to have its access released. This authorization may even be permanent: once given, the following accesses will be automatically allowed.
In a more versatile mode, a firewall can be configured to automatically allow traffic of certain types of data, such as HTTP requests (acronym for Hypertext Transfer Protocol - protocol used to access Web pages), and block others, such as connections to Internet services. email.
The IT service technician is responsible for the installation of all hardware and makes sure that network connectivity is maintained all time. In most of the companies, staffs are allotted devices such as laptops, tablets or cell phones.
Note, like these examples, that a firewall's policies are based, initially, on two principles: all traffic is blocked, except what is explicitly authorized; all traffic is allowed, except what is explicitly blocked.
More advanced firewalls can go further, directing certain types of traffic to more specific internal security systems or offering extra reinforcement in user authentication procedures, for example.