COMMUNICATION SYSTEM, VPN REPEATER AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide a communication system in which different kinds of virtual private networks(VPN) are compatible. SOLUTION: A communication system 1 is constituted by providing plural VPN devices 22A and 22B and a VPN managing server 10 equipped with correspondent VPN devices 15X, 15Y... for constructing the VPN on a communication network in cooperation with the respective VPN devices 22A and 22B. The VPN managing server 10 receives an enciphered telegraphic message by constructing the 1st VPN with the VPN device 22A of a telegraphic message transmission source and specifies the VPN device 22B of the transmission destination by deciphering the transmission destination information included in the received enciphered telegraphic message and at the same time, the 2nd VPN is constructed with the VPN device 22B of the transmission source. After the received enciphered telegraphic message is deciphered by a cryptographic key for the 1st VPN, this is enciphered by a cryptographic key for the 2nd VPN and transmitted through the 2nd VPN to the VPN device 22B.