现在一个机房的主机已经达到了一定数量，进行网络管理时，常常需要确定当前网络中处理活动状态的主机。本设计的目标就是编制程序，利用ICMP的回送请求和回送响应，来发现指定网段中的活动主机。

本设计的主体思想是使用ICMPECHO数据包来探测指定网段内的活动主机。具体方法是：通过简单的发送一个ICMPECHO(Type 8)数据包到目标主机，如果ICMPECHOReply(ICMPtype0)数据包接受到，说明主机是存活状态。如果没有就可以初步判断主机没有在线或者使用了某些过滤设备过滤了ICMP的REPLY。-now a room at the mainframe has reached a certain amount, network management, often need to determine the network address of the host state activities. The goal is to design procedures, the use of the ICMP request and sent back to send back response designated network to discover the activities of the mainframe. The design of the main idea is to use data packet ICMPECHO designated Wangduanna to detect the activities of the mainframe. The specific method is : Send a simple ICMPECHO (Type 8) data packets to the target host. If ICMPECHOReply (ICMPtype0) sees a data packet, Note mainframe is survival. If no preliminary judgment on the mainframe are not online or use of certain filtration equipment filtering ICMP inefficiency Y.