科学网

 找回密码
  注册
科学网 标签 p2p

tag 标签: p2p

相关帖子

版块 作者 回复/查看 最后发表

没有相关内容

相关日志

区块链很热门(171012)
热度 4 ymin 2017-10-12 09:10
区块链很热门( 171012 ) 闵应骅 最近区块链特热火, IEEESpectrum 2017 年 10 月号上发表了 7 篇长文是关于区块链的,还有一篇介绍中国区块链发展,国内这方面的文章就更多。我关心的是区块链的软硬件有什么新的东西。大致翻了一下,有点失望。没有人谈区块链对计算机体系结构、软件的数据结构和方法论有什么特殊的地方,主要是功能方面的创新。现在 IT 系统的功能简直是无所不包,而关注点常常是去中心化。本来,分散和集中、民主和专制问题的争论在 IT 行业持久不断。 P2P 是计算机想摆脱通讯的限制,事实证明可行,自己就可以点对点通讯;比特币想甩掉纸币,进行商品交换,试图用密码和程序取代中介服务。实质上,区块链不过是一个分布式而且安全的数据库。 一个比特令牌由一人传给另一人,与政府无关,可信性全靠一堆计算机。其他服务是不是也可以不要中间人?譬如,给视频和文艺作品的存储或重播的作者付版税、给飞机延误的旅行者付赔偿费?这三件事情已经在以太虚拟机上实现,但响应者寥寥。而区块链现在每天都有方案出现。微软给用户提供试验工具, IBM 和英特尔合作开发开源的区块链,大银行也在跟随形势,适应自己。区块链本质上是一个分布式的公共账本,任何人都可以对这个公共账本进行核查,但不存在一个单一的用户可以对它进行控制。在区块链系统中的参与者们,会共同维持账本的更新:它只能按照严格的规则和共识来进行修改,这背后有非常精妙的设计。 原则上说,钱只是一个会计工具,即体现价值、分配所有权和提供交易工具的方法。一直以来使用现金,由于制造假钞很困难,所以无需记录某人的钱是从哪里来的,也无需追究这 50 元现钞是谁印的。但如果你能跟踪每张票子的流动,这张纸就没有必要了,钞票就变成数字记录了。创造一个单一的世界通用的数字总帐就是区块链。其所以称之为链,是因为只有最终端用户得到了新信息才能产生变化,每一个新的添加或区块包含数千个链中的交易。交易检测、聚集、验证、添加区块都由一批所谓矿工 (Miner) 负责。用户的占有关系由比特币区块链确定,通过公钥和密钥。矿工的主要职责是保证交易的不可逆性。他们没有集中管理,操作自治。 比特区块链记录每一分钱的输入输出 , 及相关内容,每个记录的元数据只能用 40 字节。存储量是个大问题。而相关记录可能很多,譬如飞行保险系统还要知道何时起飞、何时降落。分布式文件共享服务可能解决这问题。可信用户是否真可信?教育记录,譬如毕业证、成绩单,索尼、 IBM 正筹建这样的区块链。各种东西都可以用区块链。但是,你是否真需要一个区块链,下面这张图回答了这问题。 据我看,这个事理论上说实现起来并没有太大的难度,但技术问题还是很多。主要问题是可靠性、安全性能不能达到人们的要求。这个问题很大,现在的微信支付、支付宝支付,许多人不敢用,就是担心它的可靠性和安全性。分散的设备容错过去做得比较少。过去对集中式的大型计算和存储设备的容错方法比较多,而让分布式的每台计算机都搞冗余就比较困难。过去强调第三方验证,特别是我们国家,你听广播、看文章,碰到问题的解决方法就是加强管理,其实就是尽量集中。管理也可能发生问题,发生贪腐的可能性更大。 当前互联网的服务平台,本质上是信任中介。比如淘宝这样的平台,除去线上买方和卖方流量,他们解决的其实就是几大问题,一个是信任和安全,一个是支付,还构建了一个买和卖的网络平台。区块链是一个超级平台,是一种按照时间顺序将数据区块以顺序相连的方式组合成的一 种链式 数据结构 , 并以密码学方式保证的不可篡改和不可伪造的分布式账本。区块链技术是利用块链式数据结构来验证与存储数据、利用分布式节点共识算法来生成和更新数据、利用密码学的方式保证数据传输和访问的安全、利用由自动化脚本代码组成的智能合约来编程和操作数据。空洞地可以这样讲,实现和推广可不那么容易。是不是能得到广大群众和政府的认可,还需要走着瞧。
个人分类: 学术导航|11324 次阅读|14 个评论
P2P之NAT类型检测方法
yangtaolyt 2014-3-5 11:24
P2P之NAT类型检测方法 P2P的NAT研究 第一部分:NAT介绍 第二部分:NAT类型检测 第一部分: NAT介绍 各种不同类型的NAT(according to RFC) Full Cone NAT: 内网主机建立一个UDP socket(LocalIP:LocalPort) 第一次使用这个socket给外部主机发送数据时NAT会给其分配一个公网(PublicIP:PublicPort),以后用这个socket向外面任何主机发送数据都将使用这对(PublicIP:PublicPort)。此外,任何外部主机只要知道这个(PublicIP:PublicPort)就可以发送数据给(PublicIP:PublicPort),内网的主机就能收到这个数据包 Restricted Cone NAT: 内网主机建立一个UDP socket(LocalIP:LocalPort) 第一次使用这个socket给外部主机发送数据时NAT会给其分配一个公网(PublicIP:PublicPort),以后用这个socket向外面任何主机发送数据都将使用这对(PublicIP:PublicPort)。此外,如果任何外部主机想要发送数据给这个内网主机,只要知道这个(PublicIP:PublicPort)并且内网主机之前用这个socket曾向这个外部主机IP发送过数据。只要满足这两个条件,这个外部主机就可以用自己的(IP,任何端口)发送数据给(PublicIP:PublicPort),内网的主机就能收到这个数据包 Port Restricted Cone NAT: 内网主机建立一个UDP socket(LocalIP:LocalPort) 第一次使用这个socket给外部主机发送数据时NAT会给其分配一个公网(PublicIP:PublicPort),以后用这个socket向外面任何主机发送数据都将使用这对(PublicIP:PublicPort)。此外,如果任何外部主机想要发送数据给这个内网主机,只要知道这个(PublicIP:PublicPort)并且内网主机之前用这个socket曾向这个外部主机(IP,Port)发送过数据。只要满足这两个条件,这个外部主机就可以用自己的(IP,Port)发送数据给(PublicIP:PublicPort),内网的主机就能收到这个数据包 Symmetric NAT: 内网主机建立一个UDP socket(LocalIP,LocalPort),当用这个socket第一次发数据给外部主机1时,NAT为其映射一个(PublicIP-1,Port-1),以后内网主机发送给外部主机1的所有数据都是用这个(PublicIP-1,Port-1),如果内网主机同时用这个socket给外部主机2发送数据,第一次发送时,NAT会为其分配一个(PublicIP-2,Port-2), 以后内网主机发送给外部主机2的所有数据都是用这个(PublicIP-2,Port-2).如果NAT有多于一个公网IP,则PublicIP-1和PublicIP-2可能不同,如果NAT只有一个公网IP,则Port-1和Port-2肯定不同,也就是说一定不能是PublicIP-1等于 PublicIP-2且Port-1等于Port-2。此外,如果任何外部主机想要发送数据给这个内网主机,那么它首先应该收到内网主机发给他的数据,然后才能往回发送,否则即使他知道内网主机的一个(PublicIP,Port)也不能发送数据给内网主机,这种NAT无法实现UDP-P2P通信。 第二部:NAT类型检测 前提条件:有一个公网的Server并且绑定了两个公网IP(IP-1,IP-2)。这个Server做UDP监听(IP-1,Port-1),(IP-2,Port-2)并根据客户端的要求进行应答。 第一步:检测客户端是否有能力进行UDP通信以及客户端是否位于NAT后? 客户端建立UDP socket然后用这个socket向服务器的(IP-1,Port-1)发送数据包要求服务器返回客户端的IP和Port, 客户端发送请求后立即开始接受数据包,要设定socket Timeout(300ms),防止无限堵塞. 重复这个过程若干次。如果每次都超时,无法接受到服务器的回应,则说明客户端无法进行UDP通信,可能是防火墙或NAT阻止UDP通信,这样的客户端也就不能P2P了(检测停止)。 当客户端能够接收到服务器的回应时,需要把服务器返回的客户端(IP,Port)和这个客户端socket的(LocalIP,LocalPort)比较。如果完全相同则客户端不在NAT后,这样的客户端具有公网IP可以直接监听UDP端口接收数据进行通信(检测停止)。否则客户端在NAT后要做进一步的NAT类型检测(继续)。 第二步:检测客户端NAT是否是Full Cone NAT? 客户端建立UDP socket然后用这个socket向服务器的(IP-1,Port-1)发送数据包要求服务器用另一对(IP-2,Port-2)响应客户端的请求往回发一个数据包,客户端发送请求后立即开始接受数据包,要设定socket Timeout(300ms),防止无限堵塞. 重复这个过程若干次。如果每次都超时,无法接受到服务器的回应,则说明客户端的NAT不是一个Full Cone NAT,具体类型有待下一步检测(继续)。如果能够接受到服务器从(IP-2,Port-2)返回的应答UDP包,则说明客户端是一个Full Cone NAT,这样的客户端能够进行UDP-P2P通信(检测停止)。 第三步:检测客户端NAT是否是Symmetric NAT? 客户端建立UDP socket然后用这个socket向服务器的(IP-1,Port-1)发送数据包要求服务器返回客户端的IP和Port, 客户端发送请求后立即开始接受数据包,要设定socket Timeout(300ms),防止无限堵塞. 重复这个过程直到收到回应(一定能够收到,因为第一步保证了这个客户端可以进行UDP通信)。 用同样的方法用一个socket向服务器的(IP-2,Port-2)发送数据包要求服务器返回客户端的IP和Port。 比较上面两个过程从服务器返回的客户端(IP,Port),如果两个过程返回的(IP,Port)有一对不同则说明客户端为Symmetric NAT,这样的客户端无法进行UDP-P2P通信(检测停止)。否则是Restricted Cone NAT,是否为Port Restricted Cone NAT有待检测(继续)。 第四步:检测客户端NAT是否是Restricted Cone NAT还是Port Restricted Cone NAT? 客户端建立UDP socket然后用这个socket向服务器的(IP-1,Port-1)发送数据包要求服务器用IP-1和一个不同于Port-1的端口发送一个UDP数据包响应客户端, 客户端发送请求后立即开始接受数据包,要设定socket Timeout(300ms),防止无限堵塞. 重复这个过程若干次。如果每次都超时,无法接受到服务器的回应,则说明客户端是一个Port Restricted Cone NAT,如果能够收到服务器的响应则说明客户端是一个Restricted Cone NAT。以上两种NAT都可以进行UDP-P2P通信。 注:以上检测过程中只说明了可否进行UDP-P2P的打洞通信,具体怎么通信一般要借助于Rendezvous Server。另外对于Symmetric NAT不是说完全不能进行UDP-P2P达洞通信,可以进行端口预测打洞,不过不能保证成功。
2 次阅读|0 个评论
P2P软件挖掘外文教程电子版不错
热度 2 outcrop 2012-12-27 12:14
有些外文教程有电子版,或者有人扫描成了电子版。 但一般网络上不大好找,一方面因为比较专业,另一方面可能也因为版权的缘故。 不过P2P工具上,找外文资料,经常还是可能有不错的收获。 不过有点像钓鱼,得靠运气。 推荐两个挖外文资料比较方便的P2P软件: emule 。电骡,不是中国版的;中国版的不能搜索,外文资源也少。 Shareaza 。支持多种P2P协议,也不错。 Mldonkey 。前面两款软件都是GUI的,比较好操作。但Mldonkey占用资源少,支持多种p2p协议,使用麻烦,适合专业、长期下载。 另外还有一些BT站有不错的外文资料,不过可能更麻烦。 =============================关于博主============================= 博主的主要兴趣是:知识管理;相关兴趣有:语义网、机电及DIY、哲学与心理、信息安全、科幻等。 我的常用博客在科学网 (访问可点链接,下同); 新浪微博是@outcrop ,欢迎互粉;建了一个超级QQ群:17662971,希望能闲聊无白丁,欢迎加入;自己打理着一个 机电工程师 小网站,欢迎来玩。最近在科学网关注“ 科学网大学 ”,欢迎加入 科学网大学群组 讨论、尝试。
个人分类: 计算机应用技术|3622 次阅读|6 个评论
International Conference on Peer-to-Peer Computing
huangfuqiang 2012-7-21 16:50
P2P'12(proceedings) P2P'11 (proceedings) P2P'10 (proceedings) P2P'09 (proceedings) P2P'08 (proceedings) P2P'07 (proceedings) P2P'06 (proceedings) P2P'05 (proceedings) P2P'04 (proceedings) P2P'03 (proceedings) P2P'02 (proceedings) P2P'01 (proceedings)
个人分类: 计算机网络理论与工程|2992 次阅读|0 个评论
2012届硕士-年治家-基于P2P网络的协作缓存策略的研究
tmdvc 2012-3-12 19:59
2012届硕士-年治家-基于P2P网络的协作缓存策略的研究
年治家__基于P2P网络的协作缓存策略的研究.pdf ppt-1
个人分类: 实验室硕士论文|2990 次阅读|0 个评论
review: Reputation Estimation and Query in
jiangdm 2012-2-19 10:23
review:  Reputation Estimation and Query in
Reputation Estimation and Query in Peer-to-Peer Networks Xing Jin, S.-H. Gary Chan IEEE Communications Magazine • April 2010 ABSTRACT Many peer-to-peer systems assume that peers are cooperative to share and relay data. But in the open environment of the Internet, there may be uncooperative malicious peers. To detect malicious peers or reward well behaved ones, a reputation system is often used. In this article we give an overview of P2P reputation systems and investigate two fundamental issues in the design: reputation estimation and query . We classify the state-of-the-art approaches into several categories and study representative examples in each category. We also qualitatively compare them and outline open issues for future research. 1 INTRODUCTION selfish behavior in P2P: malicious actions andmalicious peers KaZaa examples a reputation system:To detect malicious peers or reward well behaved ones, three functional components of a P2P reputation system: -- collecting information on peer behavior --scoring and ranking peers, -- responding based on peers’ scores. the following consideration of reputation system: • Scalability • Adaption to peer dynamics • Security the goal of this paper: to study two fundamental issues in P2P reputation systems -- Reputation estimation: how to generate peer reputation based on others’ feedback. -- three categories: social network, probabilistic estimation, and game-theoretic model. -- Reputation query: -- First, efficient data storage and retrieval is always a challenging issue in P2P networks. -- Second, reputation data are highly security-sensitive -- three categories the organization of this paper: 1) Section 2 explore the reputation estimation issue. 2) Section 3then discuss reputation query techniques. 2 REPUTATION ESTIMATION three reputation estimation methods in current P2P networks: -- The first one is the social network, where all feedback available in the network are aggregated to compute peer reputation. -- The second one is probabilistic estimation, which uses sampling of the globally available feedback to compute peer reputation. -- The third one is the game-theoretic model, which assumes that peers have rational behavior and uses game theory to build a reputation system. 2.1 SOCIAL NETWORK two categories of RS (reputation system) based on social network: -- separated reputation model --correlated reputation model a separated reputation model : -- only the direct transaction partners of a peer (e.g., resource provider/downloader or streaming neighbor) can express their opinion on the reputation of the peer. -- example: eBay,PeerTrust a correlated reputation model: --the reputation of a peer is computed based on the opinion of its direct transaction partners as well as third party peers. -- Example: EigenTrust, the network information and control exchange (NICE) reputation model { author remark: The correlated reputation model is more like our real social network, where third-party peers can express their opinion on a peer. But it takes more cost to collect and aggregate third-party opinion. For example, EigenTrust takes a long time to wait for reputation values to converge.} 2.2 PROBABILISTIC ESTIMATION assumption: methods: -- maximum likelihood estimation -- Bayesian estimation 2.3 GAME-THEORETIC MODEL 3 REPUTATION QUERY the purpose of this section: discuss techniques for reputation query in P2P networks. 3.1 CENTRALIZED AND PARTIALLY CENTRALIZED STRUCTURES The simplest solution: the centralized reputation system, eBay centralized approaches vs.partially centralized approaches 3.1 STRUCTURED OVERLAY distributed hash table (DHT) PeerTrust P-Grid 3.2 UNSTRUCTURED OVERLAY XREP:a polling algorithm four operations of XRep: -- resource searching --vote polling --- vote evaluation --- resource downloading 3.3 COMPARISONS 4 CONCLUSION I comment: the logic of paper is clear. Reputation estimation and query in peer-to-peer networks.pdf
个人分类: Network|0 个评论
review: 一种新的基于概率统计论的P2P 网络信任模型
jiangdm 2012-2-12 10:49
一种新的基于概率统计论的P2P 网络信任模型 徐海湄 齐守青 卢显良 韩 宏 电 子 与 信 息 学 报 2011-6 摘 要: 经典的P2P 网络信任模型采用迭代方法由局部信任值推算出全局信任值,每次交易都要引起整个网络节 点的迭代运算,导致计算复杂,通信流量大,并且面临交易数据过于稀疏,计算不够精确从而容易陷于恶意节点的共谋、诋毁和睡眠等攻击问题。为了保证数据的稠密性与计算结果的精确性,论文基于概率统计理论,提出了一种新的全局信任模型。该模型根据节点的历史交易情况,运用最大似然估计,假设检验等方法计算出节点的信任度,节点选择与可信度高的节点进行交易。数学分析与仿真实验表明该模型能有效地抵抗恶意节点的攻击,与经典信任模型Eigentrust 相比,较大程度地提高了整个P2P 网络的成功交易率。 关键词: 对等网络;概率统计论信任模型;最大似然估计;假设检验;交易历史记录 1 引言 P2P 网络: 信任机制 -- EigenTrust -- PeerTrust the common drawbacks: 迭代方法由局部信任值推算出全局信任值,每次交易要引起整个网络节点的迭代运算,导致计算复杂,通信流量大,并且容易陷于恶意节点的冒名、诋毁和共谋攻击。 the work of this paper:提出一P2P 全局信任模型PStrust(Probability and Statistics based trust model) -- 克服了基于迭代方法的信任模型的计算复杂性,使全局信任值可以精确表示节点的可信程度 -- 对恶意节点的攻击等安全问题进行综合考虑 2 全局信任模型PStrust 2.1 全局信任值的计算 定义1 节点的全局信任值 定义2 交易记录 最大似然估计方法 2.2 全局信任值的估计误差 定义3 节点i 的信任值θi 的置信区间与置信度 3 信任模型的安全性 3.1 诋毁与共谋攻击的抑制 诋毁: 指恶意节点故意给与之交易过的节点提供负面的评价,例如成功的交易被记录为不成功 共谋攻击: 恶意节点相互勾结,诋毁团伙外的节点,抬高对同伙的评价 恶意节点分为: 简单恶意节点,恶意集体,策略恶意节点3 类 the idea of this paper: 采取假设检验方法将恶意节点筛选出,用诚实节点反馈评价评估节点真实信任值 假设检验法 3.2 睡眠攻击的抑制 睡眠攻击: 4 仿真实验 PeerSim 实验评估标准: -- 下载成功率SDR(Successful Download Rate) I comment: I don't know what contribution of this paper? author exemplify the statistical knowledge but not incorprate its with their trust model. 一种新的基于概率统计论的P2P网络信任模型.pdf
个人分类: Network|1 次阅读|0 个评论
review: 基于连续行为观察的P2P网络中邻居评价模型
jiangdm 2012-2-11 20:42
基于连续行为观察的P2P网络中邻居评价模型 谢 振 毕经平 李 晔 计算机研究与发展 Journal of Computer Research 2010 摘 要   基于荣誉的信任机制是对P2P 网络节点行为进行评价的重要手段,用来保证P2P 网络应用的 健康进行. 信任机制在对一个节点进行评价时需要获得其他节点的局部信任值信息. 目前局部信任值的 计算由于 不考虑 策略节点和人类评价误差两种重要因素的影响,难以准确反映网络节点的特征. 提出了 一种P2P 网络中邻居行为的评价模型PeerSt rategy ,该模型使用确定的有限状态机(DFA) 对邻居连续 行为的状态变化进行刻画. 通过关注邻居在任意连续行为中引起负面评价的概率,既能够较为准确地发 现网络中的策略节点,又能够容忍一定程度的人类评价误差. 仿真实验表明,该模型显著提高了局部信 任值的准确度,并降低了对全局信任值估计误差影响,明显优于当前的其他局部信任值计算方法. 关键词  P2P 网络;信任机制;荣誉;策略节点;人类评价误差 0 引言 question: 如何评价P2P 网络中的节点,特别是分辨出恶意节点显得至关重要 eBay 信任机制: 用户反馈系统 局部信任值 全局信任值 策略节点: 采用每隔几次合作后背叛的策略 ,期望在背叛后仍然能够获得较高的局部信任值 obstacle: 如何抵御策略节点的破坏 + 人类评价误差影响,是局部信任值计算所要解决关键问题. the existing methods: 简单平均, 移动平均, 贝叶斯学习 the work of this paper: 本文提出一个邻居行为评价模型PeerStrategy , -- 该模型通过对邻居的连续行为的观察,关注邻居在任意连续交易中引起负面评价的概率, -- 考虑节点的评价误差,从而能够帮助节点较为准确地评价邻居的行为. 1 相关工作 P2P 网络信任管理系统 -- Managing Trust -- PeerTrust -- EigenTrust -- PowerTrust -- Gossip Trust the principle: 依赖于每个节点所提供的局部信任值来计算全局信任值 3 类计算局部信任值计算方法: 简单平均、移动平均和贝叶斯学习方法. 2 PeerStrategy 模型包括两部分内容: 一是邻居行为类型判断方法,通过对邻居的连续行为的观察来判断邻居的类型; 另外一部分是局部信任值计算方法,来计算节点对邻居的整体评价. 2.1 邻居行为类型判断方法 2.1.1 邻居行为类型判断方法的DFA 描述 确定性有限自动机(DFA) 2.1.2 邻居行为判断方法分析 1-. 节点宽容度参数 2-. 特征分析 宽容度α: 在邻居的一次行为引起负面评价后,接下来的两轮交易中被遗忘,或者以概率α在更多轮数后被遗忘,α体现了节点的宽容程度,也表示了容忍人类评价误差的程度 2.2 局部信任值计算 2.3 PeerStrategy 特征分析 PeerStrategy 总体特征: 1-. 善意 2-. 容错性 3-. 可激怒 4-. 宽容性 3 模拟实验 3.1 模拟实验参数设定 P2P 仿真软件Peersim 极大似然估计(MLE): 计算邻居的全局信任值 3.2 模拟实验结果及其分析 4 总  结 I comment: this paper use game theory to differentiate the different category of peer node. In order to discover the strategical node, it utilize DFA to memorize the past behavior of peer node and apply tolerant factor. From my view, the DFA is more Markove chain than DFA to describe the probability of node state 基于连续行为观察的P2P网络中邻居评价模型.pdf
个人分类: Network|2 次阅读|0 个评论
review: 基于多维历史向量的P2P2分布式信任评价模型
jiangdm 2012-2-10 15:30
review:  基于多维历史向量的P2P2分布式信任评价模型
基于多维历史向量的P2P分布式信任评价模型 谭振华 王兴伟 程维 常桂然 朱志良 计算机学报 2010 摘要: P2P网络的开放性,匿名性和对等性使P2P网络得到了广泛的应用,同时也滋生了大量的恶意节点.传统的中心化认证的信任模式无法满足P2P网络的分布式要求,分布式信任机制是P2P网络得以进一步发展的关键技术,文中基于社会网络的一些基本理论,提出了一种新的P2P2分布式信任模型MDHtrust,设计了多维交易历史向量模型及其分布式存储结构,并由此定义了局部和全局的多维因子计算方法,包括非线性时间因子,交易额度,交易频率以及成功率,构建了局部信任度全局信任度的计算方法,最终通过计算节点间交易历史的相关性,形成了具有相关性因子的全局信任度$即相关性信任度,仿真结果表明HMDTrust具有较快的信任收敛速度,是一种有效的信任模型 关键词: 对等网络 信任模型 P2P安全 社群网络 网络安全 多维历史向量 1引言 P2P: 对等性,匿名性,开放性以及松耦合性等特点 个体A对个体B信任: 指个体A期望个体B为A服务(即执行A的利益所依赖的动作)的主观可能性 P2P对等网络的可信安全 the orangization ofthis paper: 1) 第2节介绍多维历史向量的定义 2) 第3-5节对MDHTrust中的局部信任模型,全局信任模型,相关性信任模型的构建过程进行论述 3) 第6节进行仿真和实例说明 4) 最后第7节对全文进行总结和展望 2 多维历史向量 MDHTrust: Multi-dimension history Trust model 2.1 基本数据结构定义 2.2 分布式存储结构 3 局部信任度 3.1 时间因子 4 全局信任度 4.1 全局信任度因子 5 相关性信任度 6 仿真性能分析与实例说明 E=A 6.1 仿真性能分析 7 结论与展望 基于多维历史向量的P2P分布式信任评价模型.pdf
个人分类: Network|0 个评论
review: 2D Euclidean Distance Transform Algorithms:
jiangdm 2012-1-4 09:14
review:  2D Euclidean Distance Transform Algorithms:
Contents 1 2D Euclidean Distance Transform Algorithms: A Comparative Survey 1 2D Euclidean Distance Transform Algorithms: A Comparative Survey RICARDO FABBRI, LUCIANO DA F. COSTA,and JULIO C. TORELLI and ODEMIR M. BRUNO ACM Computing Surveys, Vol. 40, No. 1, Article 2, Publication date: February 2008. Abstract: The distance transform (DT) is a general operator forming the basis of many methods in computer vision and geometry, with great potential for practical applications. However, all the optimal algorithms for the computation of the exact Euclidean DT (EDT) were proposed only since the 1990s. In this work, state-of-theart sequential 2D EDT algorithms are reviewed and compared, in an effort to reach more solid conclusions regarding their differences in speed and their exactness. Six of the best algorithms were fully implemented and compared in practice. KeyWords and Phrases: Distance transform, exact Euclidean distance map, Dijkstra’s algorithm, shape analysis, computational geometry, performance evaluation 1. OVERVIEW 2. OBJECTIVES 3. ORGANIZATION This work is organized as follows. 1)Section 4 presents the formal definitions required for a precise understanding of the ideas. 2) Section 5 usesan account of DT applications to illustrate its importance and its relation to other entities. 3) Section 6 illustrates the importance of the Euclidean metric, motivating the need for efficient EDT schemes. 4) Section 7 explain the main recent EDT algorithms 5) Section 8 describes the methodology for speed and exactness tests. 6) Section 9 shows the results of the tests 7) Finally, Section 10 lists the main contributions of this work, and future activities. 4. DEFINITIONS 4.1. Main Concepts 2D Euclidean Distance Transform Algorithms.pdf
1 次阅读|0 个评论
review: GRAP: Grey risk assessment based on projection
jiangdm 2011-11-25 17:35
review: GRAP: Grey risk assessment based on projection
Contents 1 GRAP: Grey risk assessment based on projection in ad hoc networks 2 移动自组网中非完全信息节点风险评估 GRAP: Grey risk assessment based on projection in ad hoc networks Fu Cai Gao Xiang Liu Minga, Liu Xiaoyang , Han Lansheng , Chen Jing abstract: In this paper, we discuss the risk assessment of ad hoc networks, which have highly dynamic topology, open access of wireless channels, and vulnerable data communication. Conventional risk assessment methods are subjective and unreliable as some nodes reveal little information, and the quantity of samples is limited in ad hoc networks. To solve this problem, we propose a GRAP method , which includes grey relational projection (GRP), grey prediction, and grey decision making. Our scheme is designed to assess nodes’ risk under limited circumstances such as small number of samples, incomplete information and lack of experience. Compared with principal component analysis, GRAP has demonstrated better performance and more flexible characteristics. To further the practicability of this method, we utilize a dynamic grey prediction, which shows high accuracy for decision making. In our scheme, four major nodes’ attributes are selected, and the experiment results suggest that our model is more effective and efficient for risk assessment than principal component analysis in ad hoc networks. 1. Introduction the characteristic of ad hoc networks: self-organization, non-central authority, dynamic topology, and open access of wireless channels The security challenges current solution: trust or reputation evaluation the two category of assessment methods: probability and fuzzy theory 移动自组网中非完全信息节点风险评估 付才 洪亮 彭冰 韩兰胜 徐兰芳 计算机学报 2009-4 摘要:   移动自组网是一种无中心、自组织以及多跳的无线网络,能否有效可靠地对通信节点进行风险评估是保障节点高质量通信的重要因素.当前基于可信度或是信誉的评估方法对评估样本都有特殊的要求,对评估对象提出种种假设,无法辨别间接样本的恶意推荐问题,在实际移动自组网中各个节点尤其是恶意节点对外暴漏的信息往往偏少,样本数量有限,无法明确判断其状态,大部分是非完全信息,从而导致评估结果缺乏客观性与可靠性.文中提出采用 灰色系统理论 描述通信节点非完全信息状态,根据灰类白化以及灰色聚类思想进行节点风险评估.方案针对自组网络通信需求对节点行为进行多关键属性划分,采用味集群方法收集原始样本,避免恶意推荐;将难以用数值精确刻画的关键属性以白化权函数量化,引入灰聚类的概念和计算方法,将实体的通信风险水平定义为实体关键属性值序列针对各评估灰类的聚类评估值,从而得到该实体通信风险水平的相对参考值.分析与实际计算表明该方法是一种适合移动自组网中非完全信息节点风险评估的有效方法. 关键词:  移动自组网;风险评估;灰色理论;非完全信息 1 引言 风险评估 necessity current solution: 可信度或是信誉的角度 (1)基于权重的信任传递方法 (2)基于概率的信任模型 (3)基于证据理论的信任模型 (4)基于主观逻辑的信任模型 (5)模糊集合理论 ad-hoc network 自私节点问题 灰色理论 风险评估 in ad-hoc network 3个方面的核心问题: (1)需要解决样本获取的问题 (2)要解决恶意推荐即间接样本的问题 (3)样本的聚集与应用问题 the organization of this paper: 1) 第2节对灰色系统理论做一个基础描述,并证明灰数白化函数存在定理; 2) 第3节描述恶意节点评估方案,证明方案中各节点样本聚类权满足灰色关联度3个必要条件; 3) 第4节针对实验数据进行实例计算; 4) 第5节对本文的非完全信息节点风险评估机制特点进行总结. 2 基本概念 定义1 评估节点集、味集群 定义2 灰数、灰类集 3 移动自组网节点风险评估方案 the outline of this section: 1) 首先对被评估节点进行关键属性定义,得到关键属性集合 2) 各个评估节点对这些关键属性进行监测后,将样本数据发给t0,通过选择,得到味集群, 3) 对每个味集群样本进行量化单位统一化处理以及指标多极性处理后,进行灰聚类计算, 4) 最后通过味集群决策得出结论 3.1 非完全信息节点风险评估框架 3.2 非完全信息节点风险评估流程 4 实例计算 4.1 关键属性定义 security: 1) 一类是采用常规的“硬安全”措施,比如各种分布式数字签名、群签名、通信加密等; 2) 另外一类是“软安全”,如节点风险评估 节点的行为风险评估 要素 :需要定义关键属性,即确定评估指标 关键属性 + ad-hoc network 4.2 灰类集定义 4.3 白化函数定义 4.4 灰色聚类评估与味集群决策 4.5 灰色聚类算法复杂性分析 5 小结 I comment: in this paper (in chinese), what I am interesting is how to build risk model for ad-hoc network by means of grey model. for grey model, Ihave nointeresting. but I notice this process to build mathematical model. First, author select the key index for ad-hoc network, which includes avability and reliability index. Second, to set the threshold for selecting index Third, clustering and group decision by means of gray model I consider this process clear my some question. I will read it. 移动自组网中非完全信息节点风险评估.pdf
个人分类: Network|1 次阅读|0 个评论
Kai Hwang
jiangdm 2011-10-24 09:47
Kai Hwang
Contents 1 Kai Hwang PowerTrust: A Robust and Scalable Reputation System for Trusted Peer-to-Peer Computing Fuzzy Trust Integration for Security Enforcement in Grid Computing 2 1 Kai Hwang PowerTrust: A Robust and Scalable Reputation System for Trusted Peer-to-Peer Computing Runfang Zhou,and Kai Hwang IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS,2007 Abstract: Peer-to-Peer (P2P) reputation systems are essential to evaluate the trustworthiness of participating peers and to combat the selfish, dishonest, and malicious peer behaviors. The system collects locally -generated peer feedbacks and aggregates them to yield the global reputation scores. Surprisingly, most previous work ignored the distribution of peer feedbacks . We use a trust overlay network (TON) to model the trust relationships among peers. After examining the eBay transaction trace of over 10,000 users, we discover a power-law distribution in user feedbacks. Our mathematical analysis justifies that power-law distribution is applicable to any dynamically growing P2P systems, either structured or unstructured. We develop a robust and scalable P2P reputation system, PowerTrust, to leverage the power-law feedback characteristics. The PowerTrust system dynamically selects small number of power nodes that are most reputable using a distributed ranking mechanism. By using a look-ahead random walk strategy and leveraging the power nodes, PowerTrust significantly improves in global reputation accuracy and aggregation speed. PowerTrust is adaptable to dynamics in peer joining and leaving and robust to disturbance by malicious peers. Through P2P network simulation experiments, we find significant performance gains in using PowerTrust. This power-law guided reputation system design proves to achieve high query success rate in P2P file-sharing applications. The system also reduces the total job makespan and failure rate in large-scale, parameter-sweeping P2P Grid applications. Index Terms: Peer-to-Peer system, overlay network, distributed hash table, reputation system, eBay trace data set, distributed file sharing, P2P Grids, PSA benchmark, system scalability. 1 INTRODUCTION reputation management examples: eBay and its drawbacks trend: calculate the global reputation scores by aggregating peer feedbacks in adistributed manner six key issues for designing a cost-effective P2P reputation system: . High accuracy . Fast convergence speed . Low overhead . Adaptive to peer dynamics . Robust to malicious peers . Scalability the common ignorance of previous work: ignored the distribution of peer feedbacks or assumed an arbitrary random distribution the organization of this paper: 1) Section 2 reviews existing work on P2P reputation systems. 2) Section 3 introduce the new PowerTrust system concept and the use of trust overlay network. 3) Section 4 analyze the eBay trace data to reveal the powerlaw distribution of peer feedbacks. 4) Section 5 specifies the detailed design ofPowerTrust system and the reputation aggregation algorithms used. 5)Section 6 evaluate the performance attributes of the PowerTrust system 6) Section 7 report its application benchmark results 2 RELATED WORKS 3 OUR POWERTRUST SYSTEM APPROACH 3.1 The PowerTrust System Concept five functional modules of the system: 1) The regular random walk module: supports the initial reputation aggregation. 2) The look-ahead random walk (LRW) module: to update the reputation score,periodically. 3)a distributed ranking module: to identify the power nodes. 3.2 Trust Overlay Network (TON) TON: a virtual network on top of a P2P system 4 POWER-LAW DISTRIBUTION OF PEER FEEDBACKS Power-law distribution Three key parameters: 1) The feedback amount of a node 2) Feedback frequency 3) The ranking index 4.1 Collection Procedure of eBay Reputation Data 4.2 Feedback Distribution in eBay Reputation Data linear-regression 4.3 Feedback Distribution Analysis in P2P Systems two factors of the power-law feedback distribution : 1) dynamic growth of TON size 2) preferential node attachment next step: why power-law feedback distribution applies to P2P reputation systems in general? 5 POWERTRUST SYSTEM CONSTRUCTION the outline of this section : to give three construction algorithms 1) the initial construction, 2) distributed ranking, 3) updating process of the PowerTrust system. 5.1 Look-Ahead Random Walk (LRW) PowerTrust: feedback scores are generated by Bayesian learning or by an average rating the trust matrix R the eigenvector of the trust matrix R recursive process: motivated by the Markov random walk, 5.2 Distributed Ranking Mechanism PowerTrust; uses a Distributed Hash Table (DHT)to implement the distributed ranking mechanism. locality preserving hashing (LPH) 5.3 Initial Global Reputation Aggregation 5.4 Global Reputation Updating Procedure 6 SYSTEM PERFORMANCE ANALYSIS analyzed criterion: 1) reputation convergence overhead, 2) ranking discrepancy, 3) aggregation errors by malicious peers 6.1 Simulation Setup and Experiments Performed 6.2 Reputation Convergence Overhead convergence overhead : measured as the number of iterations before the global reputation convergence vs EigenTrust approach 6.3 Reputation Ranking Discrepancy 6.4 Effects of Malicious Peer Behaviors root-mean-square (RMS) 7 P2P APPLICATION BENCHMARK RESULTS the benchmark: PSA, parameter sweeping applications 7.1 Query Success Rate in Distributed File Sharing 7.2 P2P Grid Performance over the PSA Workload 8 CONCLUSIONS AND FURTHER WORK the purpose of this paper : the design experiences and simulated performance of a new P2P reputation system,PowerTrust. the contributions are summarized in four aspects: 1. Power-law distribution of peer feedbacks: 2. Fast reputation aggregation, ranking, and updating 3. System scalability and wide applicability 4. System robustness and operational efficiency further work: 1. Coping with peer abuses and selfishness 2. Reputation system for unstructured P2P System 3. Explore new killer P2P applications 个人点评: 好文章,层次清楚,观点新颖,具有应用价值!多读! PowerTrust A Robust and Scalable Reputation.pdf 又一篇中文翻译版: 基于幂律分布的P2P信誉评估机制.pdf Fuzzy Trust Integration for Security Enforcement in Grid Computing Shanshan Song, Kai Hwang, and Mikin Macwan IFIP International Federation for Information Processing 2004, LNCS Abstract. How to build the mutual trust among Grid resources sites is crucial to secure distributed Grid applications. We suggest enhancing the trust index of resource sites by upgrading their intrusion defense capabilities and checking the success rate of jobs running on the platforms. We propose a new fuzzy-logic trust model for securing Grid resources. Grid security is enforced through trust update, propagation, and integration across sites. Fuzzy trust integration reduces platform vulnerability and guides the defense deployment across Grid sites. We developed a SeGO scheduler for trusted Grid resource allocation. The SeGO scheduler optimizes the aggregate computing power with security assurance under fixed budget constraints. The effectiveness of the scheme was verified by simulation experiments. Our results show up to 90% enhancement in site security. Compared with no trust integration, our scheme leads to 114% improvement in Grid performance/cost ratio. The job drop rate reduces by 75%. The utilization of Grid resources increased to 92.6% as more jobs are submitted. These results demonstrate significant performance gains through optimized resource allocation and aggressive security reinforcement. 1. Introduction fuzzy logic the interaction between two Grid Resource sites The organization of this paper 1) Section 2 present author's distributed security architecture at USC GridSec project. 2) Section 3 introduces the fuzzy logic for trust management. 3) Section 4 describes the process of fuzzy trust integration. 4) Section 5 introduces the optimized resource allocation scheme. 5) Section 6 reported all experimental results. 2. GridSec Project for Trusted Grid Computing Virtual Private Networks (VPNs) vs PKI 3. Fuzzy Logic for Trust Management Two advantages of using fuzzy-logic to quantify trust in Grid applications are: (1) Fuzzy inference is capable of quantifying imprecise data or uncertainty in measuring the security index of resource sites. (2) Different membership functions and inference rules could be developed for different Grid applications, without changing the fuzzy inference engine. the trust index: job success rate and self-defense capability Fuzzy inference : a process to assess the trust index in five steps: (1) Register the initial values of the success rate Φ and defense capability Δ. (2) Use the membership functions to generate membership degrees for Φ and Δ. (3) Apply the fuzzy rule set to map the input space (Φ - Δ space) onto the output space (Γ space) through fuzzy ‘AND’ and ‘IMPLY’ operations. (4) Aggregate the outputs from each rules (5) Derive the trust index through a defuzzification process. fuzzy inference rules 4. Trust Integration Across Grid Resource Sites trust index trust vector the new trust index from the old value and present stimulus Trust update and trust propagation processes are specified in Algorithms 1 and Algorithm 2, respectively two simulation terms : the trust index_TTL and trust vector_TTL 5. Optimization of Trusted Resource Allocation the goal: Based on the fuzzy trust model, we present below in Algorithm 3 the SeGO scheduler for optimized Grid resource allocation. A job is submitted with the descriptor Job = (W, D, T, B), representing the workload, execution deadline, minimum trust, and budget limit Algorithm 4 specifies the trust integration process, in which n jobs are mapped to m sites 6. Simulation Results on Trusted Grid Resource Allocation 7. Conclusions and Suggestions for Further Research 个人点评: 这篇文章主要是基于trust model的 Grid resource allocation. 算法描述方式可借鉴 Fuzzy trust integration for security enforcement in grid computing.pdf
个人分类: Network|0 个评论
review: The EigenTrust Algorithm for Reputation Management
jiangdm 2011-10-22 12:38
review: The EigenTrust Algorithm for Reputation Management
《The EigenTrust Algorithm for Reputation Management in P2P Networks》 Sepandar D. Kamvar,Mario T. Schlosser,Hector GarciaMolina WWW 2003 ABSTRACT Peer-to-peer file-sharing networks are currently receiving much attention as a means of sharing and distributing information. However, as recent experience shows, the anonymous, open nature of these networks offers an almost ideal environment for the spread of self-replicating inauthentic files. We describe an algorithm to decrease the number of downloads of inauthentic files in a peer-to-peer file-sharing network that assigns each peer a unique global trust value , based on the peer’s history of uploads. We present a distributed and secure method to compute global trust values, based on Power iteration. By having peers use these global trust values to choose the peers from whom they download, the network effectively identifies malicious peers and isolates them from the network. In simulations, this reputation system, called EigenTrust, has been shown to significantly decrease the number of inauthentic files on the network, even under a variety of conditions where malicious peers cooperate in an attempt to deliberately subvert the system. Keywords: Peer-to-Peer, reputation, distributed eigenvector computation 1. INTRODUCTION 2. DESIGN CONSIDERATIONS five important issues of P2P reputation system: 1) self-policing 2) anonymity 3) profit to newcomers 4) minimal overhead 5) robust to malicious 3. REPUTATION SYSTEMS example: eBay local trust values The challenge for reputation systems in a distributed environment: how to aggregate the local trust valueswithout a centralized storage and management facility. two drawbacks of previous distributed reputation system: 1)it aggregates the ratings of only a few peers and doesn’t get a wide view about a peer’s reputation, 2)it aggregates the ratings of all the peers and congests the network with system messages asking for each peer’s local trust values at every query. author's approach: based on the notion of transitive trust 4. EIGENTRUST the EigenTrust algorithm the outline of this section: 1) Section 4.1show how to normalize the local trust values in a manner that leads to an elegant probabilistic interpretation and an efficient algorithm for aggregating these values. 2)Section 4.2 discuss how to aggregate the normalized trust values in a sensible manner. 3)Section 4.3 discuss the probabilistic interpretation of the local and global trust values. 4) Section 4.4 through Section 4.6present an algorithm for computing the global trust values. 4.1 Normalizing Local Trust Values normalized local trust value 4.2 Aggregating Local Trust Values converge 4.3 Probabilistic Interpretation rule: 4.4 Basic EigenTrust 4.5 Practical Issues three practical issues : 1) a priori notions of trust 2) inactive peers 3) malicious collectives A malicious collective assumption: pre-trusted peers are essential to this algorithm, as they guarantee convergence and break up malicious collectives. 4.6 Distributed EigenTrust challenge for a distributed system: 1)howto store relative data? 2) 4.7 Algorithm Complexity 5. SECURE EIGENTRUST two basic ideasagainst malicious peers: 1) 2) distributed hash table (DHT) 5.1 Algorithm Description 5.2 Discussion 6. USING GLOBAL TRUST VALUES two clear ways to use these global trust values inP2P system: 1)The first is to isolate malicious peers from the network by biasing users to download from reputable peers. 2) The second is to incent peers to share files by rewarding reputable peers. Isolating Malicious Peers Incenting Freeriders to Share 7. EXPERIMENTS 7.1 Simulation Network model Node model Content distribution model Simulation execution 7.2 Load Distribution in a Trustbased Network 7.3 Threat Models 7.3.1 Other Threat Models 8. RELATED WORK 9. CONCLUSION 个人点评: 似懂非懂,但是必须多次阅读. PPT: sep-kamvar.ppt the eigentrust algorithm for reputation management in p2p networks.pdf
个人分类: web service|1 次阅读|0 个评论
review: peer-to-peer systems and applications
jiangdm 2011-10-4 20:26
review: peer-to-peer systems and applications
contents: 1 peer-to-peer systems and applications 2 peer-to-peer systems and applications Steinmetz, Ralf; Wehrle, Klaus (Eds.) 2005, springer 1. Introduction 2. What Is This “Peer-to-Peer” About? Internet主要新需求: -- 规模扩展性 -- 安全性和可靠性 -- QoS 3. Past and Future Fully Decentralized Architectures 自组织网络 4. Application Areas 5. First and Second Generation of Peer-to-Peer Systems 6. Random Graphs, Small-Worlds and Scale-Free Networks Models: -- Random Graphs -- Small-Worlds – The Riddle’s First Solution --Scale-Free Networks: How the Rich Get Richer 7. Distributed Hash Tables 8. Selected DHT Algorithms Chord Pastry Content Addressable Network CAN Symphony 9. Reliability and Load Balancing in Distributed Hash Tables 10. P-Grid: Dynamics of Self-Organizing Processes in Structured Peer-to-Peer Systems
个人分类: Network|398 次阅读|0 个评论
review: A Survey on Trust Management for Intelligent
jiangdm 2011-9-14 13:57
review:  A Survey on Trust Management for Intelligent
A Survey on Trust Management for Intelligent Transportation System Shuo Ma, Ouri Wolfson,Jie Lin IWCTS’11 ACM, ACM SIGSPATIAL International Workshop on Computational Transportation Science ABSTRACT Trust management is a fundamental and critical aspect of any serious application in ITS. However, only a few studies have addressed this important problem. In this paper, we present a survey on trust management for ITS. We first describe the properties of trust, trust metrics and potential attacks against trust management schemes. Existing related works are then reviewed based on the way in which trust management is implemented. Along with the review, we also identify some open research questions for future work, and consequently present a novel idea of trust management implementation. Keywords: Trust management, Intelligent Transportation System (ITS), Entity trust, Data trust, Attack prevention 1. INTRODUCTION ITS (Intelligent Transportation System) the current work overlook a fundamental issue: trust management -- the management of the trustworthiness of relationships among entities two forms ofinterpretation of trust:entity trust anddata trust the organization of this paper: 1)Section 2 first examine the properties of trust and trust metrics, and briefly describe common attacks against trust management schemes in ITS. 2) Next, Section 3 overview the related work of trust management for ITS and show how those works are connected to the concepts. 3) Finally, Section 4 summarize our discussion and conclude our work. 2. Concepts A. Properties of Trust B. Trust Metrics C. Potential Attacks the types of attacks: -- simple false information injection attacks --on-and-off attacks -- Sybil attacks -- collusion attacks hard security vs.soft security. 3. TRUST MANAGEMENT FOR ITS A. Opinion Piggybacking B. A Novel Trust Management Scheme
个人分类: Network|0 个评论
P2P信誉与信任
jiangdm 2011-9-7 23:56
选取两篇论文 《对等网络信誉机制研究综述》,黄全能,宋佳兴,刘卫东,张军 , 小型微型计算机系统,2006 Abstract: 随着电子商务、网格、对等网络的流行信誉机制被作为一种新颖的安全问题解决方案,在国际上得到广泛研究,并取得许多重要成果,本文主要介绍面向对等网络的信誉机制的发展情况,提出一个基本框架模型,对信誉系统设计做了初步探讨, 并分析了当前一些重要研究成果,比较了他们的优点和不足,最后,概述性归纳了目前对等网络的信誉机制研究中遇到的问题, 并提出一些可能的解决思路和看法 Keywords: 对等网络;安全;信誉;信任 文献类型: 综述 研究目标: P2P网络信誉机制 研究方法: 比基尼: 难点 重点 疑点 个人点评: 此文是一篇较好的入门综述 文章不足之处: 但是此文总结力度不够,如形式化抽象功力 作者其它文献脉络 相关重要文献 对等网络信誉机制研究综述.pdf beamer_对等网络信誉机制研究综述.tex beamer_对等网络信誉机制研究综述.pdf 《对等网络信任机制研究》,李勇军,代亚非 计算机学报,2010 摘 要  对等网络环境下的信任机制是作为一种新颖的安全问题解决方案被引入的,基本思想是让交易参与方在 交易完成后相互评价,根据对某个参与方(主体)的所有评价信息,计算该主体的信任度,为对等网络中其他主体以 后选择交易对象时提供参考.文中介绍了对等网络环境下信任的基本定义.深入剖析了信任机制与网络安全的关 系,并讨论了信任机制的体系结构.根据信任机制研究的内容分别归纳总结了信任模型和信任推理方法的最新研究 成果,并选取典型的信任模型进行了评述.最后探讨了目前研究中存在的问题,并展望了需要进一步研究的方向. 关键词:  对等网络;信任模型;推理方法;典型信任算法;网络安全 文献类型: 综述 研究目标: P2P网络信任和信誉机制 研究方法: 比基尼: 难点 重点 疑点 个人点评: 此文比 黄全能 文章更进一步,无论从方法分类,图解和引用文献等方面。值得好好阅读 文章不足之处: 作者其它文献脉络 相关重要文献 beamer_对等网络信任机制研究.tex beamer_对等网络信任机制研究.pdf 对等网络信任机制研究.pdf
个人分类: Econometrics|1 次阅读|0 个评论
黄理灿:P2P是云计算的未来
huanglican 2010-8-13 20:05
黄理灿:P2P是云计算的未来 从整个计算机发展的历史看,集中式与分布式计算模式交替占住一段历史时期。如今,云计算的趋势是各个大公司建立数据中心和计算中心。然而,据我判断,这只是各个公司为了自己的商业利益以及云计算目前正处于初级阶段。当云计算的应用越来越多以及用户越来越多,集中式的计算模式将受网络带宽等因素的制约。 P2P将是云计算的未来。 云计算领域广泛采用P2P技术将在未来5年后出现。 云计算与物联网的计算模式未来5年后将主要采用P2P计算模式(即对等计算模式)。Client/Server计算模式(即客户机和服务器计算模式)主要应用于小规模的网络环境。Client/Server计算模式采用中央集中式架构,中央节点(服务器)对整个网络服务具有决定性的作用。如果服务器失效,则整个服务失效。这就是所谓的单点失效问题。此外,大部分的计算都集中在服务器端,因而引起负载的不平衡。即所谓的服务器端的计算瓶颈,而客户机端则存在资源浪费的情况。此外,集中式计算模式对用户的隐私以及数据安全也将存在不可能解决的难题。 P2P计算模式是一种非集中计算模式。P2P网络中的每台计算机(或称对等点(Peer)),具有同样的地位,既可以请求服务,也可以提供服务。P2P计算模式具有资源充分利用,网络规模可扩展(节点越多网络越稳定,不存在瓶颈)等优点。下一代计算机网络即云计算和物联网都是巨大的网络,因此,未来的计算模式应该是P2P计算模式。 目前世界上存在两种P2P网络。一种是无结构的P2P网络,采用洪泛协议发现节点。也就是节点问它所有的邻居,而邻居又问他们的所有邻居,因此网络上会引来消息风暴,造成通讯堵塞。无结构的P2P网络还存在不能保证发现适合的节点的缺点。即由于存在孤立节点不被其他节点知道,那么,这个节点就不能被发现。 二是有结构的P2P网络,采用DHT将内容与节点映射到相同格式的全局唯一标识。DHT是分布式哈希表(Distributed Hash Table)的首字缩写。DHT每个节点存储负责一个小范围的路由以及数据,从而实现整个网络的寻址和存储。此种网络的优点是每个节点都在一个虚拟的拓扑结构中,发现内容仅需要有限的消息,不会造成通讯阻塞。其缺点为节点和内容本身的语义被哈希函数打破了,不能对节点的内容进行复杂的语义查询。 本人在国际上首次提出了一种新型的P2P网络-语义P2P网络VIRGO。在此语义P2P网络VIRGO中,节点被类似DNS域名标识,, 不采用DHT的方式。节点动态地形成虚拟树拓扑,并与随机缓存的节点组成网络状拓扑结构。所有节点加入感兴趣的虚拟组,并形成虚拟分级树状拓扑结构。本人还发明了对路由表上所有类型的节点计算理论步跳的一致方法。VIRGO具有有结构的P2P网络一样的可扩展性,但保留了节点和内容的完整语义。利用VIRGO可以很方便地实现查找有关节点子集合。具体步骤包括按用户需求的主题领域确立网络领域分类、构建领域分类网络、基于领域分类网络查询节点子集合三个步骤。例如,利用VIRGO构建全球音乐网络。首先按用户需求的主题领域建立网络领域分类,例如:将音乐分为流行音乐和经典音乐。域名格式为:音乐家.音乐类别.音乐。具体域名如:LiuHuan.Popular.Music或刘欢.流行音乐.音乐。其次,构建领域分类网络,歌唱家,音乐相关公司,经纪人,消费者,粉丝等加入相关虚拟组。所有用户计算机作为节点按用户域名建立领域的覆盖网络。节点ID为用户名@域名,如:小李@刘欢.流行音乐.音乐。查询节点子集合步骤示例为:老张为贝多芬的经纪人,但目前对刘欢感兴趣。想查找所有刘欢的粉丝的属性。老张根据要查询的主题,用类SQL语音编写查询语句Select * from刘欢. 流行音乐.音乐where type=粉丝;老张节点通过查找其路由表,转发查询消息到更接近目标虚拟组域名的临近节点比如老王。老王节点转发查询消息到目标虚拟组内的小李。小李对目标虚拟组所有节点进行广播。凡符合查询消息的节点将返回结果到老张。语义P2P网络VIRGO的好处在于,任何人都不知道全局的情况(比如,任何人都不知道所有刘欢的粉丝的情况),但是通过类SQL语句,可以很方便的查到所有的信息。这是因为任何节点都是按领域加入虚拟组,只要找到相关的虚拟组,就找到所有的相关节点。 我相信,将来的网络应该是每个智能设备都有一个静态IP地址(可能是IPv6), 而所有的设备和数据通过语义P2P网络形成的一个巨大的云,及所谓的云计算和物联网, 也即智能地球。
个人分类: 生活点滴|6404 次阅读|0 个评论
有关心自己科研的导师,很庆幸
botnet 2010-4-16 20:29
今天晚饭时间没去吃饭,结果竟然正好导师在MSN上找我,问我关于博士工作的进展情况。我导师是大忙人啊,能够这么关心,主动询问我的情况,真有点让我感激涕零了。而我这段时间正苦于博士研究点的问题,本来想写一个ppt和他汇报的,可是一直没有整理好,也没敢和导师约时间。MSN中,他认为针对P2PBotnet的防御,可以作为一个切入点,还让我下周找他去拷贝相关的资料。这么一来,问题就解决了! 我常说ready+active,可到了自己这里却落实得很糟糕。导师说: 1)现在这个阶段,我的工作必须聚焦了 2)如果想针对botnet做工作,就针对具体的点走下去,不能太泛,更不能总是浮在上面 3)研究P2P Botnet的遏制问题,就先把这种Botnet的本质属性分析清楚,然后扎扎实实地做实验 4)也许能找到遏制P2P Botnet的新方法,先沿着这个点做下去,再慢慢扩展 5)不要总浮在外面,做博士一定要深入,只要能解决2-3个点上的问题,就可以了 按照导师的指示和告诫,前进! 我的导师是我非常敬佩的偶像级人物。很庆幸,自己有一位关心学生科研和发展的大牛导师。
个人分类: 科研交流|3732 次阅读|2 个评论
推荐有关P2P方面的书
huanglican 2010-3-1 06:20
Handbook of Research on P2p and Grid Systems for Service-oriented Computing: Models, Methodologies and Applications Nick Antonopoulos (Editor), George Exarchakos (Editor), Maozhen Li (Editor), Antonio Liotta (Editor) Hardcover: 894 pages Publisher: Information Science Publishing (February 5, 2010) Language: English ISBN-10: 1615206868 ISBN-13: 978-1615206865
个人分类: 未分类|4336 次阅读|0 个评论
Yale P4P Project
热度 1 huangfuqiang 2008-11-10 20:05
为了改善ISP与P2P软件服务提供商之间的不和谐,YALE的科研小组想到了一个方法体系(p4p),体现了这样的设计理念,使双方共赢. P4P, which stands for provider portal for P2P applications, is a new architecture to allow explicit and seamless communications between ISPs and P2P applications. It has the potential for making the Internet work more efficiently, in which Internet Service Providers (ISPs) and Peer-to-Peer (P2P) software providers can work cooperatively to deliver data. Current P2P information exchange schemes are network-oblivious and use intricate protocols for tapping the bandwidth of participating users to help move data. The existing schemes are often both inefficient and costly -- like dialing long-distance to call your neighbor, and both of you paying for the call. Professors Avi Silberschatz, Y. Richard Yang, and and Ph.D. candidate Haiyong Xie(国人) in Yale's Department of Computer Science are part of a research team that is involved in the engineering the P4P framework. The Yale team has played many roles in this project, ranging from naming and analyzing the architecture, to testing and to implementation of some key components of the system. T he objective is to have an open architecture that any ISP and any P2P can participate in. Yale has facilitated this project behind the scenes and without direct financial interest through a working group called P4P that was formed in July 2007 to prompt collaboration on the project. The working group is hosted by DCIA and led by working group co-chairs Doug Pasko from Verizon, and Laird Popkin from Pando. Currently, the group has more than 50 participating organizations. 谢海永 博士,首席研究员 美国分布式计算工业联盟(DCIA) P4P工作组 (P4P Working Group) 以上图片来自 谢海永研究员的PPT. 项目主页
个人分类: 计算机网络理论与工程|4938 次阅读|3 个评论

Archiver|手机版|科学网 ( 京ICP备07017567号-12 )

GMT+8, 2024-5-20 21:51

Powered by ScienceNet.cn

Copyright © 2007- 中国科学报社

返回顶部