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.
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.
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.
因此，您通常需要进行多次扫描，以识别网络中所有有效的主机。
Therefore, you often need multiple scans to be able to identify all the hosts on the network that you know are valid.
例如，要扫描192.168.0.0网络中的所有主机，您可以使用清单1中的命令。
For example, to scan all of the hosts in the 192.168.0.0 network, you could use Listing 1.
确定网络中的主机，这是最基本的网络扫描任务，并且这是了解网络运行状况的最好方式。
Determining what hosts exist on your network is the most basic of network scanning tasks, and it can be the greatest way of understanding what is going on within your network.
如果您希望扫描经过网络传输的原始数据信息，那么您需要使用一种其他工具，而不是nmap，因为它只能扫描主机和端口。
If you want to scan the raw data information that goes past on the network, you need to use a tool other than nmap, which only scans, hosts, and ports.
nmap工具提供了在整个网络上扫描主机的功能。
The nmap tool provides the ability to scan for hosts across your network.
要执行类似基本的ping测试，并识别网络中配置的所有主机，可以使用- sP命令行选项，并提供您希望扫描的IP地址规范。
To perform a basic ping test and identify all of the hosts configured on the network, use the -sp command-line option and provide the IP address specification that you want to scan.
它可以扫描所有主机自动在网络上。
安全扫描器是自动检测远端或本地网络和主机安全脆弱点的软件。
Security scanner is a program which can check automatically vulnerabilities of remote or local networks and hosts.
然后深入研究了基于网络的安全扫描与基于主机的安全扫描两种技术，并分析了两种技术的对比，对两种技术中流行的安全扫描工具进行了研究。
Then, the security scan technologies based on host and network were further researched, and the contrast of these two technologies and then introduces the popular scanner were analyzed.
本文首先对漏洞扫描的原理进行了分析，主要介绍了一种主机与网络相结合的安全漏洞扫描的设计及实现。
The analysis of the principle of the hole scanner is firstly put forward in this paper and the design and implementation of a Net-Host combined hole scanner are introduced.
本文首先对漏洞扫描的原理进行了分析，主要介绍了一种主机与网络相结合的安全漏洞扫描的设计及实现。
The analysis of the principle of the hole scanner is firstly put forward in this paper and the design and implementation of a Net-Host combined hole scanner are introduced.
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