These devices include routers, firewalls, switches, servers, load-balancers, intrusion detection systems, domain name systems, and storage area networks. These devices are ideal targets for malicious cyber actors because most or all organizational and customer traffic must pass. Network security devices are hardware or virtual appliances designed to protect computer networks from unauthorized access, data breaches, and cyberattacks. A key strategy in network security is the multi-layered defense. This document was developed in furtherance of NSA's cybersecurity missions. It encompasses various technologies, policies, and practices aimed at ensuring the confidentiality, integrity, and availability of data.