Communications system with security checking functions for file transfer operation

Abstract

A secure data communications system with an enhanced function of preventing information leakage. The system includes a user terminal and a router. The router has a security condition definition unit and a storage unit to receive and store a set of security conditions. A packet parser identifies and parses a packet produced by a file transfer application protocol and extracts from that packet a destination address and a security condition ID that the sending user has specified for a file in the packet. The packet parser discards the packet to prevent information leakage if the extracted destination address does not satisfy the security condition corresponding to the user-specified security condition ID. The user terminal has a security condition user interface that requests the router to provide information about security conditions and gives a security condition ID to each file to indicate which security condition the sending user has specified.