我们公司使用的防火墙是微软的ISA Server 2000，为了禁止内网访问某些不良网站，于是就在ISA Server2000上为这些网站创建了目标地址集，并创建了拒绝内网访问这些目标地址集的站点和内容规则。但在实践中却发现，除了web proxy客户端...我们公司使用的防火墙是微软的ISA Server 2000，为了禁止内网访问某些不良网站，于是就在ISA Server2000上为这些网站创建了目标地址集，并创建了拒绝内网访问这些目标地址集的站点和内容规则。但在实践中却发现，除了web proxy客户端外，SecureNAT和Firewall客户端仍能访问这些被禁止的网站。开始，这个问题真的让人摸不着头脑，甚至怀疑这是ISA Server 2000的Bug，不过经过一系列的分析及测试后，才发现真正的原因，如果你有兴趣，就跟着我一起来揭开这个谜吧。展开更多
网络防火墙可以实现对网络数据包进行有效过滤与拦截,是网络系统中一种非常重要的安全信息防护技术。但是传统防火墙,由于物理的硬件限制,需将防火墙设备安装在网络中多个位置,造成管理困难,并且无法对用户访问的恶意网站流量进行区别...网络防火墙可以实现对网络数据包进行有效过滤与拦截,是网络系统中一种非常重要的安全信息防护技术。但是传统防火墙,由于物理的硬件限制,需将防火墙设备安装在网络中多个位置,造成管理困难,并且无法对用户访问的恶意网站流量进行区别、分析。针对以上问题,设计了一种基于软件定义网络(software defi ned network,SDN)的防火墙系统。首先,通过SDN的可编程性自定义传输网络的规则策略与网络路由策略,实现对校园网内部的访问控制列表(access control list,ACL)控制和对网络的集中配置管理,然后,通过万维网(world wide web,Web)端界面下发防火墙规则,实现网络防火墙的过滤与拦截功能,最后,通过解析域名系统(domain name system,DNS)数据包,提取DNS主机域名,采用动态规划算法中的最短编辑距离实现DNS恶意域名防护。实验结果表明所设计防火墙系统能够使管理更加地智能化和自动化,能够提高整体网络的实时性和安全性。展开更多
Faced with hundreds of thousands of news articles in the news websites,it is difficult for users to find the news articles they are interested in.Therefore,various news recommender systems were built.In the news recom...Faced with hundreds of thousands of news articles in the news websites,it is difficult for users to find the news articles they are interested in.Therefore,various news recommender systems were built.In the news recommendation,these news articles read by a user is typically in the form of a time sequence.However,traditional news recommendation algorithms rarely consider the time sequence characteristic of user browsing behaviors.Therefore,the performance of traditional news recommendation algorithms is not good enough in predicting the next news article which a user will read.To solve this problem,this paper proposes a time-ordered collaborative filtering recommendation algorithm(TOCF),which takes the time sequence characteristic of user behaviors into account.Besides,a new method to compute the similarity among different users,named time-dependent similarity,is proposed.To demonstrate the efficiency of our solution,extensive experiments are conducted along with detailed performance analysis.展开更多
A multi-document summarization method based on Latent Semantic Indexing (LSI) is proposed. The method combines several reports on the same issue into a matrix of terms and sentences, and uses a Singular Value Decompos...A multi-document summarization method based on Latent Semantic Indexing (LSI) is proposed. The method combines several reports on the same issue into a matrix of terms and sentences, and uses a Singular Value Decomposition (SVD) to reduce the dimension of the matrix and extract features, and then the sentence similarity is computed. The sentences are clustered according to similarity of sentences. The centroid sentences are selected from each class. Finally, the selected sentences are ordered to generate the summarization. The evaluation and results are presented, which prove that the proposed methods are efficient.展开更多
文摘我们公司使用的防火墙是微软的ISA Server 2000，为了禁止内网访问某些不良网站，于是就在ISA Server2000上为这些网站创建了目标地址集，并创建了拒绝内网访问这些目标地址集的站点和内容规则。但在实践中却发现，除了web proxy客户端外，SecureNAT和Firewall客户端仍能访问这些被禁止的网站。开始，这个问题真的让人摸不着头脑，甚至怀疑这是ISA Server 2000的Bug，不过经过一系列的分析及测试后，才发现真正的原因，如果你有兴趣，就跟着我一起来揭开这个谜吧。
文摘网络防火墙可以实现对网络数据包进行有效过滤与拦截,是网络系统中一种非常重要的安全信息防护技术。但是传统防火墙,由于物理的硬件限制,需将防火墙设备安装在网络中多个位置,造成管理困难,并且无法对用户访问的恶意网站流量进行区别、分析。针对以上问题,设计了一种基于软件定义网络(software defi ned network,SDN)的防火墙系统。首先,通过SDN的可编程性自定义传输网络的规则策略与网络路由策略,实现对校园网内部的访问控制列表(access control list,ACL)控制和对网络的集中配置管理,然后,通过万维网(world wide web,Web)端界面下发防火墙规则,实现网络防火墙的过滤与拦截功能,最后,通过解析域名系统(domain name system,DNS)数据包,提取DNS主机域名,采用动态规划算法中的最短编辑距离实现DNS恶意域名防护。实验结果表明所设计防火墙系统能够使管理更加地智能化和自动化,能够提高整体网络的实时性和安全性。
基金supported by the Natural Science Foundation of China(No.61170174, 61370205)Tianjin Training plan of University Innovation Team(No.TD12-5016)
文摘Faced with hundreds of thousands of news articles in the news websites,it is difficult for users to find the news articles they are interested in.Therefore,various news recommender systems were built.In the news recommendation,these news articles read by a user is typically in the form of a time sequence.However,traditional news recommendation algorithms rarely consider the time sequence characteristic of user browsing behaviors.Therefore,the performance of traditional news recommendation algorithms is not good enough in predicting the next news article which a user will read.To solve this problem,this paper proposes a time-ordered collaborative filtering recommendation algorithm(TOCF),which takes the time sequence characteristic of user behaviors into account.Besides,a new method to compute the similarity among different users,named time-dependent similarity,is proposed.To demonstrate the efficiency of our solution,extensive experiments are conducted along with detailed performance analysis.
文摘A multi-document summarization method based on Latent Semantic Indexing (LSI) is proposed. The method combines several reports on the same issue into a matrix of terms and sentences, and uses a Singular Value Decomposition (SVD) to reduce the dimension of the matrix and extract features, and then the sentence similarity is computed. The sentences are clustered according to similarity of sentences. The centroid sentences are selected from each class. Finally, the selected sentences are ordered to generate the summarization. The evaluation and results are presented, which prove that the proposed methods are efficient.
