1. A system for interrogating a target server hosting a website or an application, the target server accessible for data communication via one or more data communication networks, comprising: an agent device connected to a private network, the agent device having a data storage area and a processor; an agent module stored in the data storage area of the agent device, the agent module configured to be executed by the processor on the agent device; a controller server communicatively coupled with said agent module via an external network and the private network, wherein communications between the controller server and the agent module pass through a security system of said private network, the controller server configured to receive monitoring messages from said agent module; a target server communicatively coupled with said agent module via one or more data communication networks, wherein the agent module is configured to send a message to the controller server, the message comprising a unique identifier for the agent module, the agent module further configured to receive a responsive message from the controller server, parse the responsive message to obtain a sequence of instructions, and execute the sequence of instructions to interrogate the target server.