Patent ID: 8312513

Claim:
An authentication system including a terminal device that is used to access a network device and a terminal authentication device that determines whether a user of the terminal device is authentic and can therefore access the network device, the terminal device and the terminal authentication device being connected to each other via a network, the authentication system comprising: the terminal device comprising: a first input unit by which an IP address of the terminal authentication device is input wherein the first input unit is a manual input unit; an authentication-request sending unit that sends an authentication request concerning whether access to the network device is permissible to the terminal authentication device using an authentication-request frame including a gratuitous ARP request in which the input IP address of the terminal authentication device is set as a sender IP address; an authentication-result receiving unit that receives a response frame from the terminal authentication device as an authentication result, the response frame responding to the authentication-request frame; an authentication-result output/display unit that outputs/displays a message indicating that the response frame is received when the response frame is received; and a network-access-information acquiring unit that acquires, from the network device, an IP address to access the network device, in response to an instruction to acquire the IP address from the first input unit, the terminal authentication device comprising: an authentication-request receiving unit that receives the authentication-request frame from the terminal device; an authentication-request output/display unit that outputs/displays a message indicating that the authentication-request frame is received when the authentication-request frame is received; a second input unit by which an authentication result indicating whether access to the network device is permissible is input; an information registering unit that registers, in the network device, when the input authentication result indicates permission to access the network device, a MAC address of the terminal device which is the sender of the authentication request as an access permitted terminal; and an authentication-result sending unit that sends the input authentication result to the terminal device which is the sender of the authentication request, after registering the MAC address in the network device is completed.