计算机网络的发展给人们在利用信息方面带来了极大的方便,但任何事情都具有两面性,随着网络的发展,安全性问题也越来越多的困扰着网络管理者的心。网络的安全问题可以分为三个不同的层次:物理层 它的主要目标是保证各种网络设备的正常运行。由于这一层次的不安全因素多半来自内部和系统本身,所以防范起来比较容易,只要注意监测各设备的运行状况,经常检修线路就可以了。软件层 在这一层上要保证网络中操作系统和各种应用软件的正常运行。对于操作系统和应用软件来说,威胁最大的恐怕要算是 The development of computer network has brought great convenience to people in using information, but everything has two sides. With the development of the network, more and more security problems plague network managers. Network security problems can be divided into three different levels: the physical layer Its main goal is to ensure the normal operation of various network devices. As this level of insecurity comes mostly from within and from the system itself, it is easier to guard against them, as long as you are careful about monitoring the health of each unit and routinely servicing the line. Software layer at this level to ensure that the network operating system and various applications running properly. For the operating system and application software, I am afraid the biggest threat is