An industrial control system (106, 506) comprising: a plurality of interconnected multiplexers (112, 114, 116, 118, 512, 514, 516, 518) forming a network, each multiplexer having a default secure lock-down mode for preventing any change to settings of the multiplexer; a physical authentication device (20, 200, 550) for indicating a physical presence of a person proximate to a control multiplexer (112, 512), the control multiplexer being one of the plurality of multiplexers; a network management computer (108, 508) connected to the network and adapted to communicate with the multiplexers, the network management computer running a network management application having a first user authentication module for authenticating a remote user; and a token generator adapted to generate a token for instructing at least one selected multiplexer to exit the secure lock-down mode to allow the user to make a change to the setting of the at least one selected multiplexer, wherein the first user authentication module is adapted to authenticate the remote user when the remote user logs onto the network by contacting the network management computer via a communication network (103, 503), wherein the control system is further adapted to establish a communication between the remote user and the person proximate to the control multiplexer, so as to allow the person to confirm the identity of the remote user as a trusted individual and to allow the person to operate the physical authentication device to generate the token; and wherein the control system is further adapted to communicate the token to the at least one selected multiplexer of the network, so that the at least one selected multiplexer exits the secure lockdown mode. a plurality of interconnected multiplexers (112, 114, 116, 118, 512, 514, 516, 518) forming a network, each multiplexer having a default secure lock-down mode for preventing any change to settings of the multiplexer; a physical authentication device (20, 200, 550) for indicating a physical presence of a person proximate to a control multiplexer (112, 512), the control multiplexer being one of the plurality of multiplexers; a network management computer (108, 508) connected to the network and adapted to communicate with the multiplexers, the network management computer running a network management application having a first user authentication module for authenticating a remote user; and a token generator adapted to generate a token for instructing at least one selected multiplexer to exit the secure lock-down mode to allow the user to make a change to the setting of the at least one selected multiplexer, wherein the first user authentication module is adapted to authenticate the remote user when the remote user logs onto the network by contacting the network management computer via a communication network (103, 503), wherein the control system is further adapted to establish a communication between the remote user and the person proximate to the control multiplexer, so as to allow the person to confirm the identity of the remote user as a trusted individual and to allow the person to operate the physical authentication device to generate the token; and wherein the control system is further adapted to communicate the token to the at least one selected multiplexer of the network, so that the at least one selected multiplexer exits the secure lockdown mode.