Remote access vpn mediation method and mediation device

A remote-access VPN mediating method in a system wherein:

• a virtual private network, hereinafter referred to as VPN, client units and a VPN gateway unit are connected to an IP network;
• communication units are connected to a local area network placed under the management of the VPN gateway unit;
• and a remote-access VPN by a tunneling protocol is implemented between an arbitrary one of VPN client units and the VPN gateway unit connected to said IP network and an arbitrary one of the communication units connected to the local area network placed under the management of the VPN gateway unit;
• said method comprising the steps of:
• (a) sending an access control list containing information indicative of a private IP address assigned to said communication unit to a mediating apparatus on said IP network from said VPN gateway unit;
• (b) storing said access control list by said mediating apparatus in correspondence to said VPN gateway unit;
• (c) retrieving an IP private address corresponding to said VPN gateway unit in response to a request from said VPN client unit, acquiring the private IP address of the corresponding communication unit from said access control list, sending the acquired private IP address to said VPN client unit, sending the IP address of said VPN client unit to said VPN gateway unit, generating mutual authentication information for setting up an authenticated encrypted tunnel between said client VPN unit and said gateway unit, and sending said mutual authentication information to both of said VPN client unit and said gateway unit;
• and
• (d) setting up said authenticated encrypted tunnel between said VPN client unit and said gateway unit by use of said mutual authentication information, and implementing remote access through said encrypted tunnel by use of the private IP address of said communication unit.