问题 问答题 简答题

边界防火墙有哪些缺陷?分布式防火墙的组成是什么,它有哪些优势?

答案

参考答案:

首先是结构性限制。随着企业业务规模的扩大,数据信息的增长,使得企业网的边界已成为一个逻辑边界的概念,物理的边界日趋模糊,因此边界防火墙的应用受到越来越多的结构性限制。其次是内部威胁。当攻击来自信任的地带时,边界防火墙自然无法抵御,被攻击在所难免。最后是效率和故障。边界防火墙把检查机制集中在网络边界处的单点上,一旦被攻克,整个内部网络将完全暴露在外部攻击者面前。分布式防火墙是三部分组成的立体防护系统:

1、网络防火墙(Network Firewall):它承担着传统边界防火墙看守大门的职责;

2、主机防火墙(Host Firewall):它解决了边界防火墙不能很好解决的问题(例如来自内部的攻击和结构限制等);

3、集中管理(Central Management):它解决了由分布技术而带来的管理问题。

分布式防火墙的优势主要有:

1、保证系统的安全性。分布式防火墙技术增加了针对主机的入侵检测和防护功能,加强了对来自于内部的攻击的防范,对用户网络环境可以实施全方位的安全策略,并提供了多层次立体的防范体系。

2、保证系统性能稳定高效。消除了结构性瓶颈问题,提高了系统整体安全性能。

3、保证系统的扩展性。伴随网络系统扩充,分布式防火墙技术可为安全防护提供强大的扩充能力。

选择题
单项选择题

Humans are social animals. They live in groups all over the world. As these groups of people live apart from other groups, over the years and centuries they develop their own habits and ideas, which form different cultures. One important particular side of every culture is how its people deal with time.
Time is not very important in non-industrial societies. The Nuer people of East Africa, for example, do not even have a word TIME that is in agreement with the abstract thing we call time. The daily lives of the people of such non-industrial societies are likely to be patterned around their physical needs and natural events rather than around a time schedule based on the clock. They cook and eat when they are hungry and sleep when the sun goes down. They plant crops during the growing seasons and harvest them when the crops are ripe. They measure time not by a clock or calendar, but by saying that an event takes place before or after some other events. Frequently such a society measures days in terms of "sleeps" or longer periods in terms of "moons". Some cultures, such as the Eskimos of Greenland measure seasons according to the migration of certain animals.
Some cultures which do not have a written language or keep written records have developed interesting ways of "telling time". For example, when several Australian aborigines want to plan an event for a future time, one of them places a stone on a cliff or in a tree. Each day the angle of the sun changes slightly. In a few days, the rays of the sun strike the stone in a certain way. When this happens, the people see that the agreed-upon time has arrived and the event can take place.
In contrast, exactly correct measurement of time is very important in modern, industrialized societies. This is because industrialized societies require the helpful efforts of many people in order to work. For a factory to work efficiently (well, quickly and without waste), for example, all of the workers must work at the same time. Therefore, they must know what time to start work in the morning and what time they may go home in the afternoon. Passengers must know the exact time that an

Which of the following might be the best title for this passage

A. Time and Culture
B. The Measurement of Time
C. Time Schedule and Daily Life
D. Clock, Calendar and Society