With the rapid development of the Internet, an increasing number of enterprises turn to network services for their company development. Customers concern more about how to protect confidential data and confidential resources on open networks. As a result, network security grows into a critical task in network construction.

• Security Threats
  At present, common security threats on Internet can be categorized into the following types: unauthorized use, Denial of Service (DoS), information theft and data tampering.
• Classification of Network Security Services
  Network security services are a set of security measures taken against security threats, including availability service, confidentiality service, Integrity service, verification service, and authorization.
• Implementation of Network Security Services
  Common network security services are carried out through encryption, authentication, access control, and security protocols.