| 摘要 |
PROBLEM TO BE SOLVED: To enable a device to protect the device from a threat of a network while enabling the device to communicate with another device even if the IP address of the other device is changed when the other device allowed to communicate with the device requests the start of communication.SOLUTION: When internal terminals 20a, 20b and a mobile terminal 20c are connected with a LAN subordinate to a home router 10, they exchange the combination of the address of a DDNS server 75 in use and the registration name of the terminal in the DDNS server 75 with each other and store it. Then, if the mobile terminal 20c moves out of the LAN and connects with a mobile communication network 65, on receiving a communication start request from the mobile terminal 20c, the internal terminal 20a reversely searches the DDNS server 75 using an IP address of the mobile terminal 20c as a key, and permits communication with the mobile terminal 20c if the obtained combination of the address in the DDNS server 75 and the registration name of the mobile terminal 20c accords with the combination stored in advance.SELECTED DRAWING: Figure 3 |
