| 摘要 |
PROBLEM TO BE SOLVED: To provide a network unit capable of detecting an unauthorized user terminal without help from a management server and/or an authentication server. SOLUTION: The network unit (layer 2 switch 2) includes a plurality of ports (Physical P101-P103), each of which each of user terminals (authorized terminals 31 and 32 and unauthorized terminal 33) is connected to. The network unit includes a user terminal information table 22 and a user terminal information checker 21. The user terminal information table 22 holds user terminal information associating a MAC address of a user terminal with information on a port where the user terminal is connected. The user terminal information checker 21 detects duplication in MAC addresses, using difference in the holding content of the user terminal information table 22 within a fixed time duration. COPYRIGHT: (C)2009,JPO&INPIT
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