2. What is network security

The main purpose of network security is to protect the assets held within the network.

Most of these assets take the form of stored data and services. But the physical equipment itself also has to be protected - after all a professional-level server is worth several thousand pounds.

The diagram below shows the kind of situations that network security efforts are trying to overcome

On the left, there are legitimate users making use of the network. But these users might accidentally harm the stored data by deleting or over-writing it. They might inadvertently make public, information that shouldn't be disclosed.

On the right side of the diagram we have unauthorised users. They can cause deliberate harm to the system by deleting, corrupting or stealing data (or even the network equipment itself). They may also gain access to services they are not authorised to use