Abstract: Based on analysis of security and confidentiality in a private network and the demand for network access control,a network access control software was designed and realized. Focused on the request of management and limitation for on-line client computers which used chipset/wireless network card in a private network, this software realized its functions by detecting the change of client IP address or other messages, triggering network control events for network monitoring and management.

Key words: Private network,Network access control,IP address change detection