The program time audit and methods time audit system, and external time measuring device

摘要

PROBLEM TO BE SOLVED: To provide a time audit system performing time synchronization and time audit of an external network and an internal network without changing setting of a communication interruption device.;SOLUTION: An external time measuring device 1 measures a time based on reliable time information received by a time audit device 4, and the external time measuring device 1 reports an external time measured based on the reliable time information to an internal time measuring device 2 by using the second communication means which is different from a communication means for communicating into an internal network through a fire wall 3. When receiving a time audit execution request from a time audit device 4, the device transmits a time reply request to the internal time measuring device 2 by using the second communication means, based on the time audit execution request, receives an internal time measured by the internal time measuring device 2 corresponding to the time reply request, from the internal time measuring device 2 through the second communication means, and calculates a time difference of the time measured, based on a time measured by own device and on the received internal time.;COPYRIGHT: (C)2010,JPO&INPIT