浅析IPSec与虚拟专用网安全技术

介绍了VPN模型和当前VPN的主要实现手段，阐述了IPSec的结构，工作模式以及工作原理，分析了基于IPSec的安全VPN的实现机制。     

虚拟专用网(VPN)的实现方法

虚拟专用网是利用Internet互联网实现企业内部低成本远程安全访问的一种。深入剖析了基于IPSec协议和L2TP协议的VPN实现方法及其安全性。着重比较IPSec和L2TP的不同模式各自的特点,为企事业单位选择VPN方案提供参考。     

虚拟专用网中IPsec的机理与实现

随着虚拟专用网（VPN）的广泛应用，其安全性正日益受重视，本文详细探讨虚拟专用网的安全标准与IPsec在虚拟专用网中的运用机理。     

运用VPN技术组建新疆党校虚拟专用网络

在党校现有的网络基础上,运用VPN技术组建新疆党校虚拟专用网,在保证数据安全性的基础上,不受干扰地远程访问内部网络资源,是党校实现网络互联和办公较为廉价的理想方法。VPN的组网方式为全疆各地州党校提供了一种低成本的网络互联模式,扩大了其专用网的范围。     

MPLS VPN在军事虚拟专用网中的应用

对军队用户需求进行系统的分析,对VPN技术进行了系统的描述,针对军事综合信息网络存在的问题,提出了构建基于MPLS技术的军事虚拟专用网的方案,以更好地满足军队用户的需求。     

虚拟专用网

随着Internet的广泛应用，虚拟专用网（VPN）技术越来越受到IT界的关注。从VPN的概念开始，介绍VPN的基本原理、主要技术、业务分类及其在Internet中的应用，指出其发展现状及市场前景。     

虚拟专用网技术

介绍了虚拟专用网（ＶＰＮ）的概念，分析了虚拟专用网的作用，提出了不同类型的虚拟 用网及其适用对象。还对虚拟专用网的四种安全协议进行了分析，指出四种安全协议的优缺点及分别最适合的虚拟专用网类型。     

VPN网络防御DOS攻击的探讨

虚拟专用网(VPN)通过加密提供安全信道,尽管VPN支持两个主机间的认证并认证后才提供VPN服务,但VPN并不拒绝试图建立连接的请求,因此,还是可以被拒绝服务(DOS)和分布式拒绝服务(DDOS)攻击,除非整个网络全部采用IPSec协议提供身份认证,否则就找不到攻击源头。针对已采用IPSec协议的VPN,文章补充了一个模块以增加其安全性并抵御中小型DOS攻击,尽量减少攻击造成的损害,并探讨了下一代网络采用IPSec必要性。     

虚拟专用网VPN及安全实现技术

介绍了虚拟专用网的概念 ,分类和使用到的相关技术 ,并且分析了VPN在实际使用中的性能问题 ,提出了解决性能问题的一些方法     

IPSec虚拟专用网技术

虚拟专用网(VPN)是最近几年才发展起来的新技术,其中以IPSec为基础的虚拟专用网技术是目前最完善的IPVPN解决方案。首先综述了IPSec协议,然后介绍了IPSec的虚拟专用网实施,最后分析了中国国内VPN市场的发展趋势。     

Virtual Topology Design and Reconfiguration of Virtual Private Networks (VPNs) over All-Optical WDM Networks

This paper studies the virtual topology design and reconfiguration problem of virtual private networks (VPNs) over all-optical WDM networks. To support VPN service, a set of lightpaths must be established over the underlying WDM network to meet the VPN traffic demands and this set of lightpaths must also be dynamically reconfigurable in response to changing VPN traffic. To achieve good network performance and meet the service requirements of optical virtual private networks (oVPNs), we formulate the problem as an integer programming problem with multi-objectives and present a general formulation of the problem. In the formulation, we take into account the average propagation delay over a lightpath, the maximum link load, and the reconfiguration cost with objectives to minimize the three metrics simultaneously. The formulated problem is NP-hard and is therefore not practical to have exact solutions. For this reason, we use heuristics to obtain approximate optimal solutions and propose a balanced alternate routing algorithm (BARA) based on a genetic algorithm. To make the problem computationally tractable, we approximately divide BARA into two independent stages: route computing and path routing. At the route computing stage, a set of alternate routes is computed for each pair of source and destination nodes in the physical topology. At the path routing stage, an optimal route is decided from a set of alternative routes for each of the lightpaths between a pair of source and destination nodes. A decision is subject to the constraints and objectives in the formulation. To improve the computational efficiency, we use a genetic algorithm in BARA. Through simulation experiments, we show the effectiveness of BARA and the evolution process of the best solution in a population of solutions produced by the genetic algorithm. We also investigate the impact of the number of alternative routes between each pair of source and destination nodes on the optimized solutions.     

虚拟专用局域网业务及方案浅析

为了满足一些要求比基于帧中继的VPN更高带宽的客户，出现了一种新的业务，即虚拟专用局域网业务(VPLS)，它使用IP／MPLS来提供高度可扩展的任意连通性。文中对VPLS的出现以及运营商如何将VPLS部署为部分VPN业务的方法进行探索。     

虚拟专用网络技术

对ＶＰＮ的基本概念作简要介绍后,着重分析了ＶＰＮ的三种典型的应用方式,即Ｉｎｔｒａｎｅｔ ＶＰＮ,远程接入ＶＰＮ和Ｅｘｔｒａｎｅｔ ＶＰＮ,并对现有的一些ＶＰＮ技术进行了总结,提出了一个一般的ＶＰＮ体系结构模型。     

A Framework for Differentiated Survivable Optical Virtual Private Networks

Wavelength division multiplexed (WDM) networks are matured to provide, scalable data centric infrastructure, capable of delivering flexible, value added, high speed and high bandwidth services directly from the optical domain. Optical virtual private networks (OVPNs) make use of the concept of highly reconfigurable nature of lightpaths offered by WDM, to create secure tunnels of high bandwidth across the intelligent WDM optical transport network. An OVPN is a private connection between two or more edge devices (access nodes), that allows a group of clients to fully exploit the flexibility of the switched intelligent optical network. However, OVPNs will not be a viable alternative unless they can guarantee a predictable bandwidth, availability, response time, and fault-tolerance to users. In this paper, we study the problem of dynamically establishing lightpaths for OVPNs over intelligent optical transport networks to provide varying classes of service based on the type of primary and backup lightpaths and the number of backup lightpaths, when each OVPN is specified by the desired logical connectivity and Class of Service. The type of primary and backup lightpaths determines the QoS parameters such as response time and bandwidth. Whereas, the number of backup lightpaths determines the level of fault-tolerance and availability of OVPN. Based on the service classes, any OVPN in the network falls into one of the six classes viz. single dedicated primary and single dedicated backup (SDPSDB), single dedicated primary and multiple dedicated backups (SDPMDB), single dedicated primary and single shared backup (SDPSSB), single shared primary and single shared backup (SSPSSB), single shared primary and multiple shared backups (SSPMSB), and best-effort (BE). In BE, we consider two variations—(1) OVPN as dedicated logical ring topology (DLRT) and (2) OVPN as shared logical ring topology (SLRT). We conduct extensive simulation experiments to compare and evaluate the effectiveness of different classes of OVPNs for varying network configurations–varying number of fibers, wavelengths on physical links, and number of nodes in OVPN.     

安全控制管理中心实现GSM安全通信

安全控制管理中心通过蜂窝移动通信网络,可构建蜂窝移动通信安全服务系统,为专用手机提供安全信息自动产生和分配、被动式和主动式安全信息销毁、安全数据控制以及失控专用手机追踪等安全通信管理服务,确保专用手机的使用、操作安全。论文提出专用手机利用在GSM提供的数据信道上建立的虚拟专网(VPN)来实现数字安全话音和安全数据通信,适合在国内外现有的GSM蜂窝移动通信系统上使用。