1. An out-of-band management system for computer networks, the system comprising: one or more network nodes equipped with a service processor and a management port accessible externally through a dedicated management interface other than a data transmission interfaces wherein the dedicated management interface further comprises an Ethernet-type interface; a service processor gateway management appliance, directly connected to the management ports of the network nodes, that isolates the management ports of the network nodes from direct access by a data network; and the service processor gateway further comprising a processor and a software application, executed by the processor, that provides one or more of a command line interface, a web interface and a protocol-based interface for access by one of a human operator and a network management system.