Network security typically refers to the security of computer networks, but it can also refer to the security of computer communication networks. A computer communication network interconnects several independent computers through communication equipment and transmission media, enabling information transmission and exchange between computers with the support of communication software. A computer network, on the other hand, refers to a system that connects several geographically dispersed independent computer systems, terminal devices, and data devices using communication means for the purpose of resource sharing, and exchanges data under the control of protocols. The fundamental purpose of computer networks is resource sharing, and communication networks are the means to achieve this. Therefore, if a computer network is secure, the corresponding computer communication network must also be secure and should be able to enable information exchange and resource sharing for network users. In the following text, network security refers to both computer network security and computer communication network security.
The basic meaning of security: Objectively, there is no threat; subjectively, there is no fear. That is, the object is not worried about its normal state being affected. Network security can be defined as: a network system that is not subject to any threats or infringements and can normally realize its resource sharing function. For a network to normally realize its resource sharing function, firstly, the network's hardware and software must function normally, and then the security of data information exchange must be guaranteed. As we saw in the previous two sections, the misuse of resource sharing has led to network security problems. Therefore, the technical approach to network security is to implement limited sharing.
