Method and system for improving computer network security

Computers connected to a private network are monitored and controlled through the use of a client agent that operates in association with the computer and a server client that establishing security parameters, privileges and authorizations for the computer. The invention can prevent access to certain devices according to an active security policy. Any activity of the computer, such as a request to transfer data to an external device, access a particular file, etc. is monitored and controlled by the client agent. No operations or procedures are allowed by the computer inconsistent with the active security policy. The security policy may be set by the administrator of the private network according to the user rights and position in the organization.