主机可能会关闭，某些服务可能暂时无法使用，并且在一个非常繁忙的网络中，扫描数据包可能根本无法通过。

Hosts might be down, services might be temporarily unavailable and, in a very busy network, the scanning packets simply might not have gone through.

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在本文中，您研究了一些相关的方法，可用于扫描您的网络以寻找主机和打开的端口、记录相关的信息并在经过一段时间之后对信息进行比较。

In this article, you've examined methods for scanning your network to find hosts and open ports and how to record and compare that information over time.

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即使在交换的网络中，通过对您所希望研究的主机运行数据包扫描工具，您就可以获得一些有价值的信息。

Even on switched networks, you can gain some valuable information by running the packet-scanning tool on the host you want to investigate.

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