Patent ID: 8443088

Claim:
A first file transfer server provided on a first local area network to carry out communications with an external server on a wide area network, the first file transfer server comprising: a list preparation section arranged to collect file information in the first local area network to prepare a file list; a registering section arranged to register account information of the first file transfer server in the external server; a list exchange section arranged to designate a second file transfer server on a second local area network registered in the external server to exchange file lists with the second file transfer server on the second local area network via the external server, to issue a request to the second file transfer server to send a file list, to receive and store the file list sent by the second file transfer server, and to bring the stored file list into correspondence with account information of the second file transfer server such that the account information of the second file transfer server is added to the stored file list when the stored file list is brought into correspondence with the account information of the second file transfer server, wherein the account information of the second file transfer server included in the stored file list is also registered in the external server; a request receiving section arranged to receive a request to acquire a file contained in the exchanged file list, from a communication terminal on the first local area network; a second file transfer server specifying section arranged to specify the second file transfer server on the second local area network in which the file is registered to establish a relaying communication session with the second file transfer server based on the account information of the second file transfer server that has been added to the stored file list; an acquisition request section arranged to issue a request to the second file transfer server to acquire the file; and a file receiving and sending section arranged to receive the file from the second file transfer server on the second local area network via the relaying communication session and to send the file to the communication terminal on the first local area network; wherein the file is retrieved from a separate file server on the second local area network by the second file transfer server in response to the second file transfer server receiving the request to acquire the file.