1. A system for controlling the operation of and access to selected computer resources of at least a first server computer by at least one subscriber client computer via an untrusted network in an operating session, without necessarily controlling access to other computer resources provided by the first server computer and by other server computers and nonsubscriber client computers, comprising: clearinghouse means for storing identity data of said first server computer and the identity data of each of said subscriber client computers server software means installed on said first server computer adapted to forward its identity data and identity data of each subscriber client computer to said clearinghouse means at the beginning of an operating session in which access to selected computer resources of said first server computer is requested; client software means installed on each of said subscriber client computers adapted to forward its identity data to said first server computer at the beginning of an operating session in which access to selected computer resources is requested; said clearinghouse means being adapted to authenticate the identity of said subscriber client computer responsive to a request for selected computer resources of said first server computer by a subscriber client computer; said clearinghouse means being adapted to authenticate the identity of said first server computer responsive to said subscriber client computer making the request for selected computer resources of said first server computer; said clearinghouse means being adapted to permit access to said selected computer resources responsive to successful initial authentication of said first server computer and of said subscriber client computer making said request.