To wait until a manager deletes the information of a spoofed ARP packet manually from an ARP table on an apparatus on which the information of a spoofed ARP packet is registered, or until information of a spoofed ARP packet is erased automatically from an ARP table of the apparatus on which the information of a spoofed ARP packet is registered when connection is restored.

A connection controller is connected with a network including: an apparatus with which connection is not permitted; and an apparatus with which connection is permitted; and an external apparatus for transmitting a command. The connection controller includes a means for transmitting a packet including false address information of a permitted apparatus at least to a non-permitted apparatus upon receiving an interruption command of a non-permitted apparatus from the external apparatus, and transmitting a packet including correct address information of a permitted apparatus at least to a non-permitted apparatus upon receiving an authorization command of a non-granted apparatus from the external apparatus.