A network security system is a set of devices, either hardware of software-based, that uses secure protocols and cryptographic algorithms to protect the information and communication systems of a company
Some functions of these devices are to monitor and control incoming and outgoing network traffic, detection of attacks, data theft and network infrastructure protection including network bandwidth performance; service security and continuity defending against denial of service attacks, …
As the security needs of organizations get more complex, so do the network security systems and the traditional approaches, like firewalls, have to go through several changes to get adapted, being necessary the incorporation of distributed mechanisms to enforce security, decentralized trust management, and the widely spread use of cryptographic techniques (like IPSec and Virtual Private Networks).
Moreover, the network security system is just a small part (although an important one) of an organization’s information security infrastructure and must be considered together with “several other fields, such as physical security, personnel security, operations security, communication security, and social mechanisms”