A device may verify whether pinholes in a perimeter protection device are open and may determine pinhole opening and closing delays. The method for determining the pinhole opening delay may include sending a stream of packets for passing through the pinhole in the network perimeter protection device. The packets in the stream may be sent at known time intervals. The method may include receiving one or more of the packets in the stream, wherein the received packets passed through the pinhole. The pinhole opening delay may be based on an indication of the position of the first one of the packets received in the stream and the known time intervals. The pinhole closing delay may be based on the number of packets having passed through the pinhole, after sending a session termination message, and the known time intervals.