public void run() {
			byte[] ack_buffer = new byte[ACK_SIZE];
			do {
				try {
					ack_buffer = new byte[ACK_SIZE];
					DatagramPacket receivePacket = new DatagramPacket(
							ack_buffer, ack_buffer.length);
					clientSocket.receive(receivePacket);
				} catch (Exception e) {
				}
				int ack_num = Utilities.getPacketNum(ack_buffer);

				if (checkForPacket(ack_buffer) == false) {
					addPacket(ack_buffer);

				}

			} while (!end);
		}