基于DHCP Snooping的校园网ARP防范研究

针对校园网普遍存在的ARP攻击、私设DHCP服务器和IP地址冲突等问题,经过分析ARP攻击原理,并结合本院实例给出了基于DHCP Snooping的校园网ARP防范解决方案。     

基于DHCP Snooping的校园网ARP防范研究

针对校园网普遍存在的ARP攻击、私设DHCP服务器和IP地址冲突等问题,经过分析ARP攻击原理,并结合本院实例给出了基于DHCP Snooping的校园网ARP防范解决方案。     

校园网DHCP故障与解决

使用动态IP地址分配方式,完成DHCP服务器的安装与部署并非难事,但是要想真正配置好、维护好校园网DHCP并非易事。因此本文结合校园网DHCP的维护经验,从三个方面对DHCP典型故障做分析。     

基于端口隔离静态IP地址冲突防范策略

校园网络中不可避免会出现IP地址冲突.通过分析ARP协议,提出基于VLAN端口隔离利用二层协议重定向策略和DHCP RELAY安全绑定建立一种高效静态IP和MAC管理策略.解决在VLAN和接入交换比较多情况下IP-MAC绑定的繁杂重复工作,避免启用DHCP SERVER不能准确定位接入主机IP地址缺点.经过实验和实际应用实现了静态IP地址冲突防范.     

有线校园网地址定位方法研究

本文介绍一种基于DHCP协议的IP地址定位方案。网络设备通过DHCP协议的82属性将IP地址位置信息数据插入DHCP请求数据包。再由DHCP服务器从地址租约文件读取IP位置数据后上传到查询服务器,最后由查询服务器完成数据的整理和合并,并向网络管理员提供查询界面。研究了校园网中不同层次的交换机的配置方法、位置信息数据格式转换的方法。     

基于DHCP技术的独立学院校园网应用

本文通过研究DHCP技术在独立学院校园网的应用,使校园网络管理员能轻松高效地对全网的IP地址等信息进行配置和管理。首先搭建了一个校园局域网,然后模拟仿真了4种校园网常见场景,应用DHCP技术进行配置等操作,查看他们是否符合预想的现象。结果表明DHCP技术在校园网中运用完全是可行的。     

DHCP协议优化方案研究

在深入研究动态主机配置协议基础上,针对协议中DHCP服务器无法获得非DHCP客户机IP地址,而造成DHCP客户机二次或多次启动协议过程和非DHCP客户机地址不能高效回收分配的缺陷,提出了改进的DHCP服务器端地址分配方案和改进的非DHCP客户机地址重用机制。利用DHCP服务器对预分配的地址进行预先冲突检测,解决了多次无效DHCP协议过程的问题;利用优先分配退出网络内非DHCP客户机的地址,提高了网络内IP地址利用效率;并在Linux平台下实现和测试了协议优化方案。     

DHCP协议深入分析

DHCP是IETF为实现IP的自动配置而设计的协议,它可以为网络客户机自动分配IP地址、子网掩码以及缺省网关等TCP／IP参数。了解DHCP的工作过程可以有效解决局域网中有关DHCP服务的问题。通过现网抓取报文,深入分析了DHCP协议的工作原理和工作流程。     

校园网内配置IP地址的解决方案

文章针对因校园网接入点迅速增加，IP地址分配难的问题，提出两种解决方案，实践证明通过DHCP服务器为用户自动分配IP地址的方案，既方便用户，也减少了网络维护的工作量。     

校园网防护ARP欺骗案例应用

对校园网内存在ARP欺骗现象,利用DHCP Option 82应用与交换机防范技术相结合,实现用户IP与MAC地址自动绑定,有效控制了校园网内部ARP欺骗。     

DHCP技术在清华大学校园网中的应用

随着网络规模的日益扩大以及人们对网络的移动性的要求越来越高,如果仍采用静态地址分配的方法进行ＩＰ管理,会给用户带来诸多不便,也给网络管理员增加很多工作量。采用动态主机配置技术进行ＩＰ管理,可以很好地解决这些问题。文章简要地介绍了 ＤＨＣＰ技术的工作原理,以及 ＤＨＣＰ技术在清华大学校园网中的应用。实践表明,ＤＨＣＰ技术对管理大规模的以及对网络移动性要求高的网络系统具有重要的意义。     

Networking without Dynamic Host Configuration Protocol server in Ethernet and Wireless Local Area Network

A Dynamic Host Configuration Protocol (DHCP) server is a well-known server deployed at a network to manage Internet Protocol (IP) addresses temporarily rentable to hosts in the network. Besides, a DHCP server provides hosts with important network information such as the subnet mask and the gateway IP address. However, a DHCP server has many drawbacks and should not be considered necessary in each network. If no DHCP server exists in a network to serve hosts and no network administrator helps users manually configure the hosts, currently no practical solution can make the hosts access networks.In this paper, Automatic Host Configuration Mechanism (AHCM) is proposed to make a host access Ethernet and Wireless Local Area Network (WLAN) without a DHCP server. AHCM can automatically locate IP addresses usable to hosts and find network information in a transparent way without any user interference. Working like protocol software inside an Operating System (OS), AHCM has high compatibility because of neither modifying any application nor deploying a third party server in a network. Most importantly, AHCM does not have drawbacks in a DHCP server. AHCM is implemented in the protocol stack on Windows XP and tested in several experiments to identify its overheads and performances.     

基于校园网存储系统的解决方案

分析校园网存储系统的特点,对DAS,NAS,FCSAN和IPSAN技术进行对比分析,结合需求重点分析基于ISCSI协议的IPSAN存储系统的技术特征,并对IPSAN的优势进行说明,由此提出基于SAN与NAS一体化以及分级存储的校园网网络存储解决方案,以满足校园网所面对的数据安全、可靠存储及有效利用的挑战和需要。     

NT平台下TCP/IP网络集成的实现方法

基于B／S与C／S体系结构集成的应用模式,是当今网络集成研究与应用开发的热点,也是该文所要探讨的目标.文中构造了一个Windows NT平台下的TCP／IP网络集成框架,讨论了基于IIS、DHCP、WINS、DNS和RAS集成服务功能的网络集成原理,提出了基于ISAPI接口实现的信息交换方法.并通过典型案例开发,验证了NT平台下TCP／IP网络集成功能的有效性.     

动态主机配置协议泛洪攻击在软件定义网络中的实时防御

在软件定义网络（SDN）中，动态主机配置协议（DHCP）泛洪攻击报文通常能通过reactive方式主动地进入控制器，对SDN危害巨大。针对传统的DHCP泛洪攻击防御方法无法阻止SDN中该攻击带来的控制链路阻塞这一问题，提出一种DHCP泛洪攻击的动态防御机制（DDM）。DDM包含检测模型和缓解模型。在检测模型中，不同于他人提出的静态阈值检测方法，采用DHCP流量均速和IP池余量两个关键参数建立动态峰值估计模型来评估端口是否受到攻击，若受到攻击则交由缓解模型进行防御。在缓解模型中，利用地址解析协议（ARP）的应答特点进行IP池清洗，并设计了周期内分时段拦截机制对攻击源进行截流，在缓解阻塞的同时，最大限度减少拦截对用户正常使用的影响。仿真实验结果表明，相对静态阈值检测，DDM检测误差平均降低18.75%。DDM缓解模型能高效地拦截流量，同时将用户在拦截期正常接入网络的等待时间平均缩短81.45%。     

Automated configuration of TCP/IP with DHCP

The TCP/IP suite has various protocols that must be carefully configured so that networked devices operate efficiently. Setting values by hand is time-consuming and error-prone; moreover, several trends are adding to the need for automated parameter configuration and administration. The Dynamic Host Configuration Protocol, accepted as a proposed standard by the Internet Engineering Task Force, offers a way to automatically configure network devices that use TCP/IP. These devices use DHCP to locate and contact servers, which return the appropriate configuration information as data. The DHCP servers act as agents for network administrators and automate the process of network address allocation and parameter configuration. Addresses can be assigned and individual addresses can be reassigned to new DHCP clients without explicit intervention by a network administrator. The IETF's Dynamic Host Configuration (DHC) working group is now at work adding new features to DHCP. The author describes the group's work on DHCP in detail, outlines the management of a DHCP service, and discusses new DHCP features, including the version being developed for IPv6     

An efficient solution to a retrial queue for the performability evaluation of DHCP

The Dynamic Host Configuration Protocol (DHCP) is designed to provide an automatic mechanism for the allocation, configuration and management of IP addresses and TCP/IP protocol stack parameters of computers and devices in IP networks. The important feature of DHCP is a “dynamic allocation” mechanism, which assigns an IP address to a client for a limited period of time (called a lease time). Therefore, a previously allocated IP address can automatically be assigned to another host by a DHCP server upon the expiration of the lease time if a host does not renew the use of an allocated IP address.This paper proposes a retrial queueing model to approximate the performability of the DHCP dynamic allocation mechanism. An efficient computational algorithm is developed to calculate the steady state probabilities of a continuous time discrete state Markov process. A comparison of our approximate model with a detailed simulation model of the DHCP dynamic allocation mechanism shows an excellent agreement between the analytical and the simulation results. The impact of the lease time parameter on the performability of the DHCP dynamic allocation mechanism is also illustrated through a numerical study.     

Mitigation of DHCP starvation attack

DHCP starvation attack is an attack that targets DHCP servers whereby forged DHCP requests are crafted by an attacker with the intent of exhausting all available IP addresses that can be allocated by the DHCP server. Under this attack, legitimate network users can be denied service. In this paper, we describe the seriousness of the attack and survey and evaluate existing solutions designed to mitigate such an attack. In addition, we propose a novel mitigation solution. Our solution overcomes the limitations of existing solutions in terms of performance, effectiveness, and flexibility. Our solution is based on dynamic fair allocation of IP addresses and is suitable for unshared and shared (wireless) access networks. We study and analyze the proposed mitigation technique through numerical examples and simulations. Furthermore, simulation results show that our proposed solution is far superior in mitigating DHCP starvation attack when compared to other existing techniques such as fixed allocation and DHCP request rate detection.     

工业以太网中DHCP协议应用技术分析

随着网络规模的日益扩大以及人们对网络的移动性的要求越来越高．如果仍采用静态地址分配的方法进行IP管理。会给用户带来诸多不便．也给网络管理员增加很多工作量。采用动态主机配置技术进行IP管理、可以很好地解决这些问题。文章简要地介绍了DHCP技术的工作原理，以及DHCP技术在工业以太网中的应用。实践表明。DHCP技术对管理大规模的以及对网络移动性要求高的网络系统具有重要的意义。     

DHCP服务在路由器与交换机上的配置应用

在Internet中,主机之间通过IP地址相互通信,因此分配、管理、设置客户端IP地址的工作尤为重要。网络管理员手工方式设置IP地址,不仅非常费力、费时,而且也容易出错,尤其在大中型网络系统中,手工设置IP地址更是一项非常复杂的工作。文章阐述了利用DHCP服务器为客户端主机自动分配IP地址等相关信息的配置方法。有效提高网络管理员的工作效率。