| 摘要 |
The present invention aims at providing a DDNS server, a DDNS client terminal and a DDNS system which maintains high security while using DHCP and allows an access to terminals having the same IP address as well as data updates. The DDNS server includes a terminal management table storing the domain name, global IP address and port number of a DDNS client terminal, characterized in that the terminal management section checks whether a same global IP address is present in the terminal management table when a request to overwrite a global IP address is made from a DDNS client terminal and, in case the same global IP address is absent, permits overwriting of the global IP address, and in case the same global IP address is present, checks the port number, and in case the same port number is detected, inhibits overwriting of the global IP address, and in case the port number is different, permits overwriting of the global IP address.
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