一种对IP地址分配的监测管理方法和实现

采用DHCP服务器自动分配IP地址,是解决IP地址不足的有效途径.但是,即使在采用DHCP的环境中,IP地址冲突的情形仍偶有发生,因为用户仍可手动设定自己计算机的IP地址,不理会DHCP所分配的网段,这种情况在校园网络屡见不鲜.文章提出一种IP地址指派的监测机制,通过SNMP网络管理协议至路由器设备检查网络中IP地址的使用情形,并通过DHCP日志文件的分析,找出违反规定使用IP地址的计算机,解决IP地址盗用与地址冲突的问题,可以有效降低网管人员的负担.     

路由器DHCP协议配置在Packet Tracer环境下的仿真实现

作为主机动态配置协议,DHCP协议能够对于网络主机的IP地址请求给予响应,并实现相关网络参数的分配。由于DHCP协议基于客户机/服务器模式,对于DHCP服务器的配置极其重要。该文描述了如何使用路由器来完成DHCP服务器的功能,以及跨网段时相关路由器的设置,并在Packet Tracer环境下实现了相应配置。     

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。     

基于Windows Server 2008下的DHCP服务器的搭建

我们知道,接入网络中的计算机如果要和其他计算机进行通信,必须要有一个合法的IP地址,手动为每一台计算机配置IP地址是比较常见的方法,但如果涉及到的计算机的数量非常多,很明显这种方法比较繁琐,我们可以采用自动获取IP地址的方法.在DHCP模式下,管理员不需要手动为每一台计算机分配IP地址,而是在网络中配置好一台DHCP服务器,每台计算机启动过程中,就会自动尝试从DHCP服务器获取一个合法的IP并使用.     

如何解决IP地址冲突

看了1月8日刊出郭永峰先生遇到的问题,简述一下我的看法,不足之处尚请指正。 首先让我们对问题的产生做一个分析。在这例情况中,有两个不同的IP地址网段,分别是111.222.1.0/24(即网络ID为111.222.1.0,掩码为24位)和100.100.0.0/24。在这两个网段中各有一台DHCP服务器为本网段的用户分配IP地址。目前的问题是两个网段的DHCF服务器互相干扰,导致用户不能正确地从服务器获得IP地址。因为DHCF分配IP地址的工作是采用广播机制,所以我们可以判定这两个网段在同一个广播域中,它们之间的连接是通过集线器或二层交换机实现的。由此推定郭先生的网络拓扑结构应如下:     

仿真软件在计算机网络通信教学中的应用

基于PacketTracer仿真软件组建了跨路由器的虚拟VLAN网络实验,分析了路由器的端口设置、IP地址分配以及交换机的详细配置方法,丰富了实验教学手段。通过具体的实验对虚拟网络进行了仿真测试分析,实现了跨路由器间的VLAN通信以及跨网络的DHCP中继服务,并在实际的网络设备上进行了试验验证。     

DHCP及其在校园网管理中的应用

DHCP协议是一种在TCP／IP网络上使客户机获得配置信息的协议，就win2000server中的动态主机配置（DHCP）功能进行了论述，并叙述了在计算机房中用DHCP分配动态IP地址的具体实现。     

Windows NT 4.0DHCP服务器的配置

为了减轻网络管理人员分配和维护IP地址的困难,Windows NT 4.0具有的动态宿主机配置协议(Dynamic HostConfiguration Protocol,简称DHCP)为用户提供了安全、可靠的TCP/IP网络配置功能,实现了IP地址的动态分配,确保不会发生地址冲突。     

应用批处理文件快速配置Windows DHCP服务器

为了便于网络管理和跟踪,局域网管理者一般都希望给局域网上每台客户机分配指定的IP地址。通过比较和试验,笔者采用DHCP保留的方法实现客户机每次获得指定的IP地址。但通过Windows 2000 Server提供的DHCP服务管理控制台配置数百个保留地址则工作量巨大。本文介绍了一种应用批处理文件快速配置DHCP保留的方法,并对相关命令作了详细的分析     

DHCP引起的一例网络故障分析与解决

随着计算机软硬件的发展,很多计算机局域网中的IP地址分配多采用服务器的DHCP服务自动获取,现在也有不少局域网是用路由器的DHCP进行分配。DHCP自动分配IP地址虽然简化了IP地址管理、部署,但随之而来的各种DHCP故障和安全问题却成为平时网络维护中的新问题。文章先分析DHCP的基本工作原理,再列举了局域网中实际碰到的因为服务器的老化造成的DHCP故障并提出具体解决措施,希望对大家平时的日常管理和维护有所帮助。     

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.     

DHCP中继在路由交换网络中的设计与应用

路由交换网络是当前流行的网络架构,DHCP是当前主流的获得IP地址协议.在现有的网络设备上利用DHCP中继技术实现动态IP地址的分配,既节省网络建设成本,又方便统一管理.在真实设备上实验表明：方案运行稳定、效率较高、无需额外的DHCP服务器且易于实现.     

DHCP协议缺点及其解决方案的研究

基于对DHCP协议的解析,针对协议中由于DHCP服务器无法获得非DHCP客户机IP地址,造成二次或多次DHCP过程发生的这一缺陷,提出了一种新的解决方案,该方案能够降低网络拥塞现象发生的可能性,提升网络的整体性能.     

DHCP协议缺点及其解决方案

基于对动态主机配置协议的解析，针对协议中由于动态主机配置协议服务器无法获得非动态主机配置协议客户机IP地址，造成二次或多次动态主机配置协议过程发生的这一缺陷，提出了一种新的解决方案，该方案能够降低网络拥塞现象发生的可能性，提升网络的整体性能。     

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.     

基于改进DHCP的IP动态伪装设计与实现

通过IP伪装来迷惑攻击者,从而防止针对特定IP的数据流分析与嗅探。文章分析了Linux系统中IP伪装技术的不足,设计并实现了一种基于改进DHCP针对网络会话的IP动态伪装。改进DHCP通过伪装IP使用频率、客户机和IP描述及IP状态变化来管理分配伪装IP,通过主动探测来确保分配IP的安全性。客户机发起新的网络会话时,通过动态申请伪装IP并跟踪网络会话来实现IP动态伪装。     

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.     

论DHCP网络协议的安全性问题与解决

DHCP技术可以有效地解决目前IP地址资源不足和无线网络用户的移动性,并极大地减轻大型网络管理员的工作量,有利于快速地搭建一个大型网络或修改其网络配置。但由于DHCP协议在设计时未考虑安全的因素,在使用DHCP服务器为主机配置网络地址和参数的网络中面临着很多DHCP威胁,所以对DHCP安全性的研究具有重大意义。该文笔者即围绕DHCP网络协议的安全性问题展开集中讨论研究,包括归纳DHCP网络安全的主要威胁、提出了消除威胁的策略建议、用对比的方式挖掘减少威胁的方法以及安全实现。     

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     

DHCP Failover研究与实验设计

DHCP服务广泛应用于大型网络架构中,为部署安全、可靠的DHCP服务器,通过对Failover协议的研究,设计基于LINUX环境下DHCP Failover应用服务器实验。介绍DHCP Failover服务器的实验配置,网络安全配置及实验结果验证等。实践证明, DHCP服务器的灾难备份有效地保证用户网络的稳定性,提高IP资源的使用效率。