Communication network system

A communication network system, comprising:

• an external device connected with a global network;
• an internal device connected with a local area network independent from the global network;
• a server communicatively connectable with the external device via the global network;
• and
• a gateway configured to relay communication between the global network and the local area network, wherein
• the server is configured to receive from the external device an access demand packet indicating a demand for an access to the internal device, and transmit a first access demand notice packet notifying receipt of the access demand packet to the gateway, via the global network, and
• the gateway includes:
• a first communication interface configured to communicate with the server via the global network;
• a second communication interface configured to communicate with the internal device via the local area network;
• a first communication controller configured to control the first communication interface to cause the first communication interface to receive the first access demand notice packet transmitted from the server to the gateway;
• a second communication controller configured to control, upon receiving the first access demand notice packet by the first communication interface, the second communication interface to cause the second communication interface to transmit a second access demand notice packet notifying the receipt of the first access demand notice packet to the internal device to establish a session between the external device and the internal device;
• and
• a communication history storage configured to store communication history information about a history of communication between the external device and the internal device after the establishment of the session, and
• wherein the gateway further includes:
• a session monitor configured to monitor the session between the external device and the internal device without reference to the communication history information stored in the communication history storage, and output impermissible access detection information when detecting an impermissible access from the external device to the internal device;
• and
• an impermissible access processor configured to perform at least one of a warning processing of notifying the impermissible access detection information and a disconnecting processing of disconnecting the communication between the external device and the internal device, when the session monitor outputs the impermissible access detection information.

A communication network system, comprising:

• an external device connected with a global network;
• an internal device connected with a local area network independent from the global network;
• a server communicatively connectable with the external device via the global network;
• and
• a gateway configured to relay communication between the global network and the local area network, wherein
• the server is configured to receive from the external device an access demand packet indicating a demand for an access to the internal device, and transmit a first access demand notice packet notifying receipt of the access demand packet to the gateway, via the global network, and
• the gateway includes:
• a first communication interface configured to communicate with the server via the global network;
• a second communication interface configured to communicate with the internal device via the local area network;
• a first communication controller configured to control the first communication interface to cause the first communication interface to receive the first access demand notice packet transmitted from the server to the gateway;
• a second communication controller configured to control, upon receiving the first access demand notice packet by the first communication interface, the second communication interface to cause the second communication interface to transmit a second access demand notice packet notifying the receipt of the first access demand notice packet to the internal device to establish a session between the external device and the internal device;
• and
• a communication history storage configured to store communication history information about a history of communication between the external device and the internal device after the establishment of the session,
• the first communication controller is configured to cause the first communication interface to periodically transmit a first periodic packet to the server at a predetermined time interval, and causing the first communication interface to receive the first access demand notice packet transmitted from the server to the gateway in response to the first periodic transmit packet.