IP端口对照表，0 通常用于分析操作系统。这一方法能够工作是因为在一些系统中“0”是无效端口，当你试图使用一种通常的闭合端口连接它时将产生不同的结果。一种典型的扫描：使用IP地址为0.0.0.0，设置ACK位并在以太网层广播。

-IP port CRT, 0 normally used to analyze the operating system. This approach can work because in some systems "0" is invalid ports, When you attempt to use a normally closed the port connecting to it will produce different results. A typical scan : using IP addresses 0 .0.0.0, set up ACK-layer Ethernet and broadcasting.