随着计算机网络的不断发展,全球信息化已成为人类发展的大趋势。但由于计算机网络具有联结形式多样性、终端分布不均匀性和网络的开放性、互连性等特征,致使网络易受黑客、怪客、恶意软件和其他不轨的攻击,所以网上信息的安全和保密是一个至关重要的问题。计算机网络安全日益成为人们关注的话题。简要的介绍了计算机网络在当代所面临的威胁,以及面对这样的威胁我们应该采取哪些安全策略。例如:物理安全策略、访问控制策略、网络的权限控制等等。 With the continuous development of computer networks, the global informationization has become a general trend of human development. However, because of the diversity of connection forms, terminal distribution unevenness, network openness and interconnectivity, the network is vulnerable to attacks by hackers, geeks, malicious software and other misdeeds. Therefore, the security of online information and Confidentiality is a crucial issue. Computer network security has increasingly become a topic of concern. Briefly introduced the contemporary computer network threats, and in the face of such threats we should take what security strategy. For example: physical security policy, access control policies, network access control and so on.