Security device, method, and non-transitory computer-readable media

A method to be executed by a security device configured to be used by being connected to a router arranged at a boundary between a Wide Area Network (WAN) and a Local Area Network (LAN) and to a main device of a key telephone system in the LAN, the method comprising:

• acquiring a first Internet Protocol (IP) address of the main device on the security device side and a second IP address of the security device on the main device side;
• forming session-establishment address correspondence, the session-establishment address correspondence associating a first type external address information unit of the main device containing the first IP address and a first session establishment port number, a first type external address information unit of the security device containing a third IP address of the security device on the router side and a second session establishment port number for a connection target telephone on the WAN side, and a terminal number and a session-establishment address information unit of the connection target telephone;
• and
• setting, to the main device, the first type external address information unit of the main device and a first type internal address information unit of the security device containing the second IP address.

A non-transitory computer-readable medium storing a control program causing a security device, the security device configured to be used by being connected to a router arranged at a boundary between a Wide Area Network (WAN) and a Local Area Network (LAN) and to a main device of a key telephone system in the LAN, to execute:

• acquiring a first Internet Protocol (IP) address of the main device on the security device side and a second IP address of the security device on the main device side;
• forming session-establishment address correspondence, the session-establishment address correspondence associating a first type external address information unit of the main device containing the first IP address and a first session establishment port number, a first type external address information unit of the security device containing a third IP address of the security device on the router side and a second session establishment port number for a connection target telephone on the WAN side, and a terminal number and a session-establishment address information unit of the connection target telephone;
• and
• setting, to the main device, the first type external address information unit of the main device and a first type internal address information unit of the security device containing the second IP address.