Linux中一种常用的引导工具是(15)；在Linux操作系统下安装网卡，如果操作系统没有内置的驱动程序，那么用户必须(16)，才能完成驱动程序的安装。为一块设备名为eth0的网卡分配D地址和子网掩码的命令是(17)。如果不打算使用DNS或者NIS进行地址解析，则必须将所有的主机名都放入文件(18)中；测试与IP地址为165.113.1.170的网关是否连通的命令是：(19)。

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While the Internet is inherently insecure, businesses still need to preserve the privacy of data as it travels over the network. To help do that, the Internet Engineering Task Force an international group of network designers, operators, vendors, and researchers concerned with the evolution of(71)has developed a suite of(72)called Internet Protocol Security(IPSec).

 IPSec creates a standard platform. to develop secure networks and electronic(73)between two machines. Secure tunneling via IPSec creates(74)connections in a network through which data packets can move. It creates these tunnels between remote users and within a local network. It also(75)each data packet in a new packet that contains the information neccessary to set up, maintain and tear down the tunnel when it's no longer needed.

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One of the difficulties in building an SQL-like query lange for the Web is the absence of a database schema for this huge, heterogeneous repository of information. However, if we are interested in HTML documents only, we can construct a virtual(66)from the implicit structure of these files. Thus, at the highest level of(67), every such document is identified by its Uniform. Resource Locator(URL), has a title and a text Also, Web servers provide some additional information such as the type, length, and the last modification date of a document. So, for data mining purposes, we can consider the site of all HTML documents as arelation:

 Document(url,(68), text, type, length, modify)

 Where all the(69)are character strings. In this framework, anindividual document is identified with a(70)in this relation. Of course, if some optional information is missing from the HTML document, the associate fields will de left blank, but this is not uncommon in any database.

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