1. A method for providing controlled access via an external network to a resource residing on an internal network, comprising: receiving at a mediating firewall associated with the internal network an external request received via the external network and addressed to the mediating firewall, the external request comprising a request from a requesting party for response data associated with an internal computer system associated with the internal network; analyzing at the mediating firewall at least part of the content of the external request to determine whether the request is authorized; and if it is determined that the request is authorized, sending from the mediating firewall to the internal computer system an internal request, generated by the mediating firewall, comprising a request for said response data.