Abstract: A flanged sleeve connector provides an interface between an end of a secure conduit and a locked enclosure. The connector has a tubular portion of at least partially rectangular or other geometric cross section, and an outwardly projecting flange of circular outer peripheral shape at an end of the first tubular portion. In use, the connector is placed over an opening in a wall of an enclosure or through wall penetration with the flange end face engaging the wall surrounding the opening, and a fastener device inside the enclosure is engaged with fastener formations on the connector to secure the connector to the enclosure. In one embodiment, the connector has a second, externally threaded portion extending from the flange into the enclosure to engage the fastener. In another embodiment, the flanged end of the connector has internal threads.