对于低级的攻击，ping流可用于偷偷地查找信息，但是如果要截取向目标发送的包，则要求系统离线或停机。

At the low end, a ping flood can be used to uncover information covertly, but throttle up the packets being sent to a target or victim so that now, the system will go offline or suffer slowdowns.

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然后该实用程序下载必要的软件包，并使用低级Debian软件包管理工具安装它们。

The utility then downloads the necessary packages and installs them using lower-level Debian package management tools.

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然而，多数包过滤是不分国家的，它们只懂得低级协议，难以配置和验证。

However, most packet-filters are stateless, understand only low-level protocols, and are difficult to configure and verify.

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