Internet and most networks use the principle of client/server. Servers across the globe provide certain types of services, and clients (PCs, laptops or mobile) connects them to access the information.
The main reasons for using so wide of this architecture are:
- storing information in one place, where it can be easily redistributed to customers;
- dedication of computing resources (servers) for specific tasks such as for example email – where safety is involved moving information from one point to another.
Customers (ie those who work with computers as a network client) can have a huge variety and can be off and on without affecting the proper functioning of the network.
What should be noted first of all that the vast majority of Internet services is that there are:
- a program (software) client on the one hand;
- a server program on the other side;
- connections between client and server;
- connections between multiple servers;
- direct connections between clients.
The transfer of files from the server to client is called downloading, and the reverse is called uploading.
In all these cases, the relevant from the point of view of security is the answer to the following questions:
- who “talks”?
- with whom?
- which way?
- what information changes?