In a local area network where communication between terminals is regulated by designating a management, or target, terminal, which is responsible for updating connecting regulation information on the other terminals, each communication terminal includes a station and a network interface. The network interface stores connecting regulation information in RAM. The network interface forwards or discards packets based on the connecting regulation information and the packet source and destination addresses. The network interface includes hardware, software, and a communication protocol designed to reduce the possibility of spoofing, where a terminal other than the target terminal changes the connecting regulation information. Each network interface includes a dip switch that is set to the target terminal's layer 2 MAC address or its layer 3 IP, or network, address. The network interface will only transmit a packet setting connecting regulation information if its own address is the same as the value in the dip switch. The network interface will only update its connecting regulation information if the packet source address equals the dip switch value. The system therefore reduces the chance of a terminal successfully pretending to be the target terminal.