PURPOSE: To provide a repeater that is not required to be directly operated on the occurrence of revision and that does not make any repeater operation for an undesired packet.

CONSTITUTION: The repeater 1 consists of a filtering database 16 storing addresses of stations, a 1st filter 15 filtering a packet based on the filtering database 16 and a destination address of the packet, a command detector 11 detecting a filtering database revision command packet from a local network, a password checker 12 checking the correctness of the password of the command detected by the command detector 11, a filtering database revision section 13 revising the filtering database 16 based on a correct check result by the password checker 12, a 2nd filter 14, receivers 17, 18 and transmitters 19, 20.