| 1.1 |  | Overview of Network Security |
| 1.1.4 |  | Key elements of network security |

| The successful use of Internet technologies requires an increased need to protect valuable data and network resources from corruption and intrusion. A security solution contains five key elements :

1. Identity
   Identity refers to the accurate and positive identification of network users, hosts, applications, services, and resources. Standard technologies that enable identification include authentication protocols such as Remote Access Dial-In User Service (RADIUS) and Terminal Access Controller Access Control System Plus (TACACS+), Kerberos, and one-time password (OTP) tools. New technologies such as digital certificates, smart cards, and directory services are beginning to play increasingly important roles in identity solutions.
2. Perimeter security
   This element provides the means to control access to critical network applications, data, and services so that only legitimate users and information can pass through the network. Routers and switches with packet filtering or stateful firewalling, as well as dedicated firewall appliances, provide this control. Complementary tools, including virus scanners and content filters, also help control network perimeters.
3. Data privacy
   When information must be protected from eavesdropping, the ability to provide authenticated, confidential communication on demand is crucial. Sometimes, data separation using tunneling technologies, such as generic routing encapsulation (GRE) or Layer 2 Tunneling Protocol (L2TP), provides effective data privacy. However, additional privacy requirements often call for the use of digital encryption technology and protocols such as IP Security (IPSec). This added protection is especially important when implementing Virtual Private Networks (VPNs).
4. Security monitoring
   To ensure that a network remains secure, it is important to regularly test and monitor the state of security preparation. Network vulnerability scanners can proactively identify areas of weakness, and intrusion detection systems can monitor and respond to security events as they occur. By using security-monitoring solutions, organizations can obtain significant visibility into both the network data stream and the security posture of the network.
5. Policy management
   As networks grow in size and complexity, the requirement for centralized policy management tools grows as well. Sophisticated tools can analyze, interpret, configure, and monitor the state of security. Browser-based user interfaces and tools enhance the usability and effectiveness of network security solutions.