Security, trust, and QoS in next-generation control and
communication for large power systems
Carl H. Hauser, David E. Bakken, Ioanna Dionysiou, K. Harald Gjermundr?d,
Venkata S. Irava and Anjan Bose
Washington State University1
Keywords: electric power grid, real-time data communication networks, middleware, power control applications
Abstract
The present communication architecture supporting control of the electric power grid makes it difficult to use the wealth of data collected at high rates in substations, retarding their use in new applications for controlling the grid. A flexible, real-time data network would make it possible to use these data for many more control and protection applications, having the potential to increase the reliability of the grid and increase its operating efficiency. Example applications that could use these data include: decentralized load frequency control; closed-loop voltage control; transient and small-signal stabilization; and special protection schemes taking advantage of data gathered over a wide area. Such applications and the flexibility of the underlying communication network imply greater sharing of data between the utilities making up the grid as well as performance, availability and reliability requirements. Mechanisms for managing security, trust, timeliness and path redundancy are thus important components of communication networks to support these control applications. This paper examines the security, trust and QoS requirements imposed by these applications and show how they are met by mechanisms included in the GridStat middleware framework that we are developing.
Introduction
New approaches to controlling the power grid are receiving increased attention in the last few years. Constrained investment in transmission infrastructure and highly visible outage events along with new monitoring and control technologies are producing pressure for a fresh look at the way information about the power grid’s operation is collected and distributed, [1,2,3,4,5]. We have previously described a new, flexible approach to providing communications support for electric power grid operations, [6]. The goal is to take advantage of modern computer networking and distributed systems knowledge to provide a communication infrastructure that can serve a multitude of communication needs for the power grid. This new approach to power grid communication offers challenges in quality of service (QoS), security and trust that do not arise in the power grid’s existing, rather fragmented, cyber infrastructure.
1 School of EECS, PO Box 642752, Pullman, WA 99163, USA. +1.509.3356470,
hauser@https://www.doczj.com/doc/f618257951.html,
The flexible architecture of [6] is intended to carry communication between substations and control centers that today is typically carried on SCADA systems, as well as supporting maintenance and configuration activities in substations which are often carried out on an outsourced basis by contracted vendors. Other intended uses include gathering and disseminating phasor measurement unit (PMU) data streams used in novel applications such as detection and remediation of under-damped small-signal instability, disturbance localization, remedial action schemes (RAS) and special protection schemes (SPS). Other potential applications include dissemination of substation status based on substation models that use redundant information collected in a single substation to derive the overall status of buses and transmission lines at that substation, [7], and other wide-area monitoring and control functions that may be invented in the future.
The architecture described in [6] is based on a publish-subscribe (pub-sub) distributed system model. Devices in substations periodically publish status and analog measurements, called status variables in the architecture; control centers and devices in other substations subscribe to a selected set of status variables. A publisher may produce data at a higher rate than a subscriber cares to receive them in which case the network will filter the data stream down to the required rate, reducing demands placed on network and subscriber resources. The network supports multiple subscribers to each status variable’s stream of data using multicast techniques.
Conventional communication systems based on SCADA and point-to-point communication are already known to have security vulnerabilities, [8]. A pub-sub architecture for power grid communication potentially poses quite different QoS and security requirements than those that arise in conventional power grid communication: the new architecture will support a vastly richer set of interactions between power grid entities than is typical with today’s architectures.
Because the new communication system enables many more interactions between many more participants, it has security requirements beyond the conventional confidentiality, integrity and availability (CIA) properties provided by conventional security systems. For example, message integrity and confidentiality services have nothing to say about the quality of the data contained in a message. Nor does a confidentiality service protect against disclosure of a message by an intended recipient. As the community of participants in the power grid’s operations grows, properties such as these become increasingly difficult to deal with. This kind of property is the domain of trust and trust management, [9, 10]. Trust is quantified belief by a trustor in the competence and dependability of a trustee to peform a specific action within a specific context. Trust management is the process by which a trustor develops and maintains its trust beliefs.
It is perhaps not surprising that security, trust, and quality-of-service requirements interact in interesting ways. The remainder of this paper exposes common themes in the security, QoS, and trust requirements imposed on the architecture by some of its intended applications and considers their consequences for the implementation of the architecture.
Application requirements for security, QoS, and trust
In present practices, different needs are met using quite different, and separate, technologies.
A flexible communication infrastructure, if it is to fulfill its promise, will have to meet the security, QoS and trust needs of many kinds of applications. Some of the intended current and envisioned future applications are described below.
Communication between substations and control centers.
Communication between substations and control centers today is the domain of SCADA systems. Equipment at substations, including so-called Intelligent Electronic Devices (IEDs), reports status and measurements, such as voltage, current and power transfer, to a SCADA Remote Terminal Unit (RTU) in the substation. A SCADA master at the control center polls
the RTU every few seconds to retrieve the measurements. An Energy Management System (EMS) at the control center displays the measurements and status to operators. The operators, in turn, issue commands to the substation equipment (e.g., to open or close a breaker, or change transformer tap).
Even this very simplified description reveals fundamental requirements for the performance of the control center.
1.Control center displays for operators must accurately reflect the system state so that
control decisions are appropriate.
2.Substation equipment carries out legitimate commands, and only legitimate
commands, within specified time delays.
3.Certain control decisions and state information are commercially or otherwise
sensitive and are not to be revealed to unauthorized parties.
On the other hand, the two-second (or even four-second) SCADA polling cycle and the almost entirely manual control system suggest that sub-second latency is not a requirement for these communications in today’s systems.
Historically, the obstacles that the power industry has addressed in meeting the first two requirements have been primarily ones associated with the reliability of substation equipment and communication systems. Problems include sensor failures, communication link failures, misconfiguration of substation equipment and databases that describe it, etc. Solutions include redundancy of communication links and use of software technology called state estimators to form an accurate picture of the system state based on partially incorrect information.
These solutions primarily address threats to the requirements posed by unreliability of equipment and errors by human beings. In recent years, malicious interference is increasingly recognized as a threat to achieving the requirements. To date, the security approaches taken to preventing malicious interference are based on attempting to guarantee that the SCADA system is a closed, isolated system and on that basis making assumptions such as:
1.Physical access to substation equipment is limited to authorized parties.
2.Physical access to the communication hardware and links is limited to authorized
parties.
3.Authorized parties are always trustworthy.
4.SCADA networks are not interconnected with networks to which unauthorized parties
have access.
5.Because links are used exclusively for SCADA communication there are no issues
associated with allocation of bandwidth for different purposes.
There is considerable accumulated evidence that existing SCADA systems do not satisfy these assumptions [8], leading to the conclusion that the electric power infrastructure is threatened by malicious attack delivered through its control system. In the last decade the extent to which the closed system assumptions were not being met has been recognized and considerable effort by utilities has gone into remedying the situation. New operational and auditing practices have improved the situation. More recently, products providing “bump-in-the-wire” encryption have become economically feasible and have seen increasing deployment.
The trend toward operating transmission systems closer to the their limits, toward outsourcing of key maintenance and configuration operations, and toward separation of the businesses of generation and transmission would be better served by the more flexible communication infrastructure discussed here. However, the security assumptions of existing SCADA systems are in conflict with the evolving need for communication that crosses organizational and geographic boundaries. For the new communication architecture it is appropriate, therefore, to
start not by imposing closed system assumptions but rather by looking at the required operational behavior and developing the security, QoS and trust requirements from there. Requirement 1: The control center displays accurately reflect the system state (so that control decisions are appropriate)
To meet this requirement the system must ensure the integrity of data that is collected at sensors and delivered to control centers and it must ensure that sensor readings are delivered within a specified time interval from when they are collected. Meeting this requirement involves both end-to-end integrity and quality of service. Furthermore, it is increasingly recognized that solving the situation awareness problem for operators,
[1], requires that control centers have up-to-date information about the state of
facilities in surrounding control areas. Operators must be convinced of the trustworthiness of the neighboring information if they are to take actions based upon it. The operators’ trustworthiness assessment may change as evidence accumulates that a party is reporting consistently and truthfully, based on other party’s reports, or that the party is reporting inaccurate information.
Public-key-based signing techniques are a potential solution to the integrity problem, but there are concerns about the computational ability of low-end and legacy sensor devices to carry out the public-key algorithms, and about the latency costs associated with the algorithms. These problems are compounded by the need to share collected data between multiple control centers and the desire to aggregate sensor measurements in substations.
Ensuring end-to-end latency of sensor data requires allocation of network resources to different source-destination flows and ensuring that the network capacity is sufficient to meet all the requirements. It is likely that the set of flows and their latency requirements will change as the operational state of the power grid or communication infrastructure changes, so the network must adapt in the face of contingencies such as link failures and cyber-attacks. The existing practice of using state estimators to augment sensor data and to protect against erroneous data provides some resilience against failure to receive information in a timely way.
The importance of trust and trust management often goes unrecognized, but a critical infrastructure’s communication system should help establish appropriate trust in the information it delivers. The greater the organizational and physical distance between the communicating entities the more important this becomes. For example, in the August 2003 blackout some operators were reluctant to believe that transmission lines had tripped out based on reports from neighboring operators, because that information conflicted with information reported by their own system. In a less technical domain, recent Congressional testimony indicated that part of the lack of timeliness in the US Dept. of Homeland Security’s response to the flooding of New Orleans following hurricane Katrina was distrust by senior officials of the reports they were receiving. Requirement 2: Substation equipment carries out legitimate, and only legitimate, commands within specified time delays
As with requirement 1, requirement 2 poses the need for integrity of messages along with a latency requirement. The latency requirements are perhaps more stringent because while the control center might be able to substitute information derived from other sensors for missing inputs, it may be quite difficult to substitute different actions when a command is not carried out. Because authority to control a device is limited to a single control center, trust is not so much of an issue for this requirement.
Requirement 3: Certain control decisions and state information are commercially or otherwise sensitive and are not to be revealed to unauthorized parties.
Requirement 3 is a confidentiality requirement. Cryptographic techniques provide a foundation on which to build a solution. More difficult problems likely lurk in techniques for distinguishing between authorized and unauthorized parties across business entity boundaries and for dynamically adapting the sets of unauthorized and authorized parties for particular information as the operating status of the power grid changes. This requirement also reveals the other side of the trust problem: disclosure to certain parties may be desirable only if their trustworthiness can be established.
From the information provider’s perspective knowing the identity of the recipient is not enough—the provider also wants to know whether the recipient can be trusted. Communication between substations and control centers is only one aspect of the power grid's cyber communication needs. While it reveals most of the qualitative aspects of the requirements and has been treated in depth, the applications that follow provide additional insight into the scope of the QoS, security, and trust needs in a flexible infrastructure. Communication between control centers
In present-day systems state information is shared between neighboring control areas EMSs using the Inter-Control Center Protocol (ICCP). ICCP allows a utility to give access to specific items in its EMS database to authenticated EMSs at other utilities. Connections can be made over private networks or virtual private networks. The shared items may be either pulled by the receiving EMS or pushed by the sending EMS. Latencies of several seconds are acceptable.
Today, operators also rely on telephone communication with operators in nearby areas to develop their overall awareness of the operating state of the grid. In an emergency situation, such as occurred leading up to the August 2003 blackout, operators may find it difficult to acquire enough reliable information over the telephone: it has limited bandwidth and a two-way conversation may not focus the operator’s attention in the best possible place for acquiring needed information.
Collection and dissemination of phasor measurement unit (PMU) data
PMUs measure current and voltage at precisely-determined times, many times per second. There is considerable interest in the power industry toward applying these synchronous measurements to new control solutions to stabilize the grid and allow it to be operated more efficiently. The Wide Area Monitoring System (WAMS) in the Western US was the first widespread deployment of PMUs, [11]. The Eastern Interconnect Phasor Project (EIPP) is currently deploying PMUs in the Eastern grid. It is setting up infrastructure for collecting the data, but is only in the early stages of considering the data's use for monitoring and control applications.
In current practice an independent network is set up to carry PMU measurements to devices called Phasor Data Concentrators (PDCs) where the full data streams from many devices are time-synchronized, stored for future reference, and forwarded to applications and Super PDCs, [11, 12].
Wide-area control and monitoring
Another use of relays in today’s grid is to protect the grid against transient instability, a phenomenon that occurs when the grid topology suddenly changes due to unexpected loss of a large transmission line, generator, or load. When a large change occurs power flows over a wide geographic area may begin to oscillate. If unchecked, the oscillations can damage generation and transmission equipment. To prevent damage, protective devices associated
with major assets will disconnect them from the grid. Unfortunately, losing too many generators or transmission lines in this way causes breakups of the grid and power outages. To prevent outages due to this phenomenon, power system engineers have created special protection schemes (SPS) that attempt to prevent the oscillations from growing, instead of waiting for the oscillations to force critical equipment to trip offline. A special protection scheme involves taking a specific action, such as tripping a generator, soon after a specific triggering event that may occur hundreds of kilometers away. Because the damaging oscillations have low frequency (often substantially below 1Hz) and the concern is preventing the buildup in amplitude of oscillations over several cycles, the communication timing requirements for special protection schemes are less stringent than those for local protective relaying. Support for SPS is a reasonable goal for a wide-area power grid communication architecture.
Because a SPS provides protection against only a predefined event at high cost and complexity, recent research has been investigating approaches that allow reaction based on sensing the response of the power grid to arbitrary disturbances, followed by corrective action such as capacitor bank switching, generator tripping, or load shedding, [13]. Related ideas include detection and mitigation of small-signal instability, [14], and fault location by detecting and triangulating based on frequency disturbances, [15]. These schemes detect anomalous behavior of the grid by monitoring the outputs of several PMUs (or frequency measurement devices in the case of [15]) and deriving indications of problems such as low voltage, incorrect frequency, or oscillations. Based on location of the problem, specific discontinuous or continuous control actions can be taken. In the Western US power grid it is estimated that control action needs to be taken within about 1 second of the occurrence of the disturbance to suppress transient instability.
Communication for local protective relaying
Protective relays monitor transmission line conditions. When faults occur they are responsible for tripping circuit breakers that de-energize the line (or other equipment). Relays may also attempt to re-close breakers; if, as often occurs, the fault was transient the equipment can be put back in service in a few seconds. The measurements for protective relaying are usually made only at the substation where the breaker is located or in a neighboring substation. The communication systems associated with relaying are, today, entirely separate from the systems used for control centers and PMU data collection. They have very stringent time requirements (only a few milliseconds latency). Local protective relaying is likely to be one of the last applications to adopt a common communication infrastructure; indeed, due to its great importance for protection of life and property and its stringent timing requirements it may never do so.
Relay settings (tripping rules) are usually statically determined from off-line analysis and simulation of the associated equipment. Better communication of overall grid conditions has the potential to allow settings to be less conservative in some operational circumstances, in turn allowing greater use of available transmission resources. Such an application would have QoS and security requirements more similar to control center requirements than to those for protective relaying.
Summary of applications’ requirements
Message confidentiality, integrity and availability (CIA) show up as requirements across the spectrum of applications. Hard latency requirements range from a few milliseconds for protective relaying to a few tens of milliseconds for automated dynamic stabilization applications and a few seconds for conventional control center applications. Applications that use inputs from a large, varying set of suppliers or make their outputs available to a large, varying set of consumers are most in need of trust management support. The communication architecture, itself, suggests that the trust management system must include support for
indirect interactions—chains of processing that involve multiple participants (including the communication infrastructure).
Implications of the requirements
The requirements identified above have several implications for QoS, security and trust and their interactions which we now elaborate.
The communication infrastructure should support CIA properties for all messages as needed by the applications. The major challenges to doing this are 1) providing these properties using computationally underpowered devices; 2) establishing an authentication infrastructure that efficiently supports the operational needs of the utility industry while providing authentication for people working in many different businesses and organizations in many different roles and for thousands of different devices; 3) establishing and maintaining policies that allow appropriate monitoring and control to occur.
While we do not propose that power grid communication be implemented using the public Internet, the cost of internet technology makes its use in private networks very attractive. We assume, for the time being, a private cyber infrastructure for the power grid based on internet technology and we look specifically at the security implications of the power grid control requirements for such a network.
The hard real-time latency requirements imply that network resources must be actively managed: best effort service is not good enough. Meeting end-to-end latency requirements for existing subscriptions means that first-come first-serve is not adequate as a scheduling discipline in nodes of the forwarding network: a guaranteed-rate packet scheduling discipline is required, [16,17]. A corollary of these observations is that the public Internet, lacking both admission control and guaranteed-rate forwarding, is not viable as part of the power grid’s control communication infrastructure. Policy mechanisms will be needed as part of the communication infrastructure to ensure that subscriptions needed for safe operation of the power grid are always admitted. Also, determining which subscriptions are most needed and which are merely nice to have will be a part of the engineering process in designing control systems in the future. The question of which subscriptions are most needed is compounded when one considers that the answer may change as power flows change.
Even on a private IP network the standard TCP byte-stream protocol is inappropriate for most of the applications described here. Although TCP provides reliable delivery its delivery model (do not deliver byte n to the application until byte n-1 has been delivered), its retransmission, window management, and timeout strategies geared to congestion control, render it unsuitable for real-time control.
The design of the communication infrastructure must also consider malicious threats to meeting QoS requirements. Denial of service through consumption of network resources is a threat that must be countered. Even though use of the public Internet has already been shown to be inappropriate, the control network design should suppose that at least from time to time, if not permanently, the two networks become connected. It must be assumed therefore that packet injections are possible so denial of service attacks cannot be prevented, but must be thwarted. Security mechanisms will have to be leveraged to prevent unwanted traffic from consuming network resources.
GridStat
For the past five years, the GridStat project has been designing a flexible power grid communication architecture and creating a publish-subscribe middleware framework instantiation of it. GridStat middleware partitions the network functions into a management plane, consisting of QoS Brokers, and a data plane consisting of status routers.
The QoS Brokers allocate resources for subscriptions, create multicast routes to be loaded into the status routers, perform admission control, and monitor the data plane, adapting it to
changing circumstances. For example, a QoS Broker can change the set of active subscriptions in response to a change in the operational status of the power grid; or it can reroute subscriptions around a failed status router or communication link.
The status routers implement a multicast-based, real-time, publish-subscribe model for providers and consumers of operational data: breaker status, bus voltage, line power transfer, etc. Unlike IP routers (network layer 3), status routers are session-aware (subscriptions) and can even incorporate application-level functionality, for example, by performing data aggregation using GridStat’s condensation function mechanism. A condensation function allows a status router to combine multiple input streams into a single output stream using a built-in or user-supplied combination rule.
Status routers incorporate a mechanism for pre-configuring sets of subscriptions (subscription modes) corresponding to different operating conditions of the power grid and making smooth transitions between them.
To increase delivery reliability, a subscription request can specify that data for the subscription be delivered over multiple, disjoint paths. Routing heuristics for efficient, delay-constrained, disjoint-path multicast are being developed as part of the project, [18].
In the GridStat prototype the QoS Brokers demonstrate disjoint-path, multicast routing, hierarchical network management and network monitoring. The status routers incorporate the ability to perform multicast forwarding, subscription modes, and condensation functions. Research is currently under way to add guaranteed-rate forwarding to the status routers to achieve guaranteed end-to-end latency, [16,17].
The status variable abstraction is provided to GridStat publishers and subscribers through middleware libraries. Recall that a status variable is a periodic sequence of time-stamped values produced by a single publisher and consumed, potentially, by many subscribers. The status variable abstraction relieves the application of some of the more difficult issues that arise in programming distributed applications. At the same time, the fact that publications are periodic makes it possible for resource scheduling in the status routers to provide guaranteed end-to-end delay.
Ongoing work
A new center-scale project was initiated in August, 2005 by the US National Science Foundation (with funding from the US Depts. of Energy and Homeland Security) in order to address many of the issues discussed in this paper. The center, Trustworthy Cyber Infrastructure for the Power Grid (TCIP), involves computer scientists and power engineering researchers from the University of Illinois, Cornell University, Dartmouth College, and Washington State University, [19]. TCIP researchers are conducting fundamental research which will be applied to wide-area communications infrastructures, such as GridStat, in order to better meet the needs described in this paper. Particular areas of research include hardware, software, and firmware to provide a reliable and secure computing base that can protect existing substation devices against accidental failures and malicious attacks; providing data communications within substations and at higher levels (e.g., to control centers and between them) which offers more security but also quantified tradeoffs between security, performance, and trust; secure data aggregation techniques to deal with malicious and other incorrect data inputs; and quantitative validation of the above technologies using simulation and modeling. Conclusion
Security and trust requirements for the power grid's cyber infrastructure are derived from the need to monitor and control grid components by multiple interacting business entities, with both cooperative and competitive interests. Creating the power grid's cyber infrastructure as an isolated network has obvious appeal, but does not solve problems associated with insider threats, nor is complete isolation likely to be achieved and maintained at all times.
Security techniques for confidentiality, integrity and availability are important components of any solution. The need to support interactions involving devices with low computational power, and to support many business entities with many people in each business pose significant challenges to the application of well-known technologies such as public key encryption and message signing.
Thwarting denial of service attacks is a key need in achieving the required quality of service.
A power grid communication infrastructure that is not intended to be open to all comers (as the Internet is) will allow controls to be placed on traffic so that the network can be protected from denial of service attacks: to work, this must be true even when cross connections to the Internet occur, as they inevitably will.
Acknowledgements
This work has been supported in part by National Science Foundation Grants CCR-03-26006 and CNS-05-24695.
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Biographies
Carl H. Hauser is an associate professor of computer science in the School of Electrical Engineering and Computer Science at Washington State University (WSU). His research interests include concurrent programming models and mechanisms, networking, programming language implementation, and distributed computing systems. Prior to joining WSU, he worked at Xerox Palo Alto Research Center and IBM Research for a total of more than 20 years. He received his BS degree in computer science from Washington State University in 1975 and his MS and PhD degrees in computer science from Cornell University in 1977 and 1980, respectively.
David E. Bakken received his BS degrees in mathematics and computer science from Washington State University in 1985, and the MS and Ph.D. in computer science from The University of Arizona in 1990 and 1994, respectively. He is currently an Associate Professor at Washington State University. He has worked at BBN Technologies (1994-1999) and Boeing (1985-1988). His research interests include middleware frameworks for wide-area systems and fault-tolerant computing.
Ioanna Dionysiou is a PhD candidate in Computer Science in the School of Electrical Engineering and Computer Science at Washington State University (WSU). Her research interests include distributed systems, security and trust in publish-subscribe models. She
received her BS and MS degrees in computer science from Washington State University in 1997 and 2000, respectively.
K. Harald Gjermundr?d is a PhD candidate in Computer Science in the School of Electrical Engineering and Computer Science at Washington State University (WSU). His research interests include distributed systems, message-oriented middleware and concurrent programming. He received his BS and MS degrees in computer science from Washington State University in 1999 and 2001, respectively.
Venkata S. Irava is a PhD candidate in computer science in the School of Electrical Engineering and Computer Science at Washington State University. His research interests include multicast routing, computer networking and distributed computing systems. He received his BE degree from Osmania University, India and MS degree from Utah State University in 1999 and 2002, respectively.
Anjan Bose received his Btech (Hons) from the Indian Institute of Technology, Kharagpur in 1967, MS from the University of California, Berkeley in 1968, and Ph.D. from Iowa State University in 1974. He has worked for the Consolidated Edison Co. of New York (1968-70), the IBM Scientific Center, Palo Alto (1974-75), Clarkson University (1975-76), Control Data Corporation (1976-81) and Arizona State University (1981-93). At present, he is the Distinguished Professor in Power Engineering in the School of Electrical Engineering and Computer Science at Washington State University. His research concerns operation and control of power grids; his methods and software are used in grid control centers around the world. He is a member of the US National Academy of Engineering and a member of the National Research Council’s Study Committee on Improving Cybersecurity Research in the United States.
齐头并进堵源治本高校校园网ARP攻击防御解决方案 DIGTIAL CHINA DIGITAL CAMPUS 神州数码网络有限公司 2008-07
前言 自2006年以来，基于病毒的arp攻击愈演愈烈，几乎所有的校园网都有遭遇过。地址转换协议ARP（Address Resolution Protocol）是个链路层协议，它工作在OSI参考模型的第二层即数据链路层，与下层物理层之间通过硬件接口进行联系，同时为上层网络层提供服务。ARP攻击原理虽然简单，易于分析，但是网络攻击往往是越简单越易于散布，造成的危害越大。对于网络协议，可以说只要没有验证机制，那么就可以存在欺骗攻击，可以被非法利用。下面我们介绍几种常见ARP攻击典型的症状： ?上网的时候经常会弹出一些广告，有弹出窗口形式的，也有嵌入网页形式的。下载的软件不是原本要下载的，而是其它非法程序。 ?网关设备ARP表项存在大量虚假信息，上网时断时续；网页打开速度让使用者无法接受。 ?终端不断弹出“本机的XXX段硬件地址与网络中的XXX段地址冲突”的对话框。 对于ARP攻击，可以简单分为两类： 一、ARP欺骗攻击，又分为ARP仿冒网关攻击和ARP仿冒主机攻击。 二、ARP泛洪（Flood）攻击，也可以称为ARP扫描攻击。 对于这两类攻击，攻击程序都是通过构造非法的ARP报文，修改报文中的源IP地址与（或）源MAC地址，不同之处在于前者用自己的MAC地址进行欺骗，后者则大量发送虚假的ARP报文，拥塞网络。 图一 ARP仿冒网关攻击示例
神州数码网络秉承“IT服务随需而动”的理念，对于困扰高教各位老师已久的ARP 攻击问题，结合各个学校网络现状，推出业内最全、适用面最广、最彻底的ARP整体解决方案。 神州数码网络公司从客户端程序、接入交换机、汇聚交换机，最后到网关设备，都研发了ARP攻击防护功能，高校老师可以通过根据自己学校的网络特点，选取相关的网络设备和方案进行实施。
S5600系列交换机典型配置举例 2.1.1 静态路由典型配置 1. 组网需求 (1)需求分析 某小型公司办公网络需要任意两个节点之间能够互通，网络结构简单、稳定， 用户希望最大限度利用现有设备。用户现在拥有的设备不支持动态路由协议。 根据用户需求及用户网络环境，选择静态路由实现用户网络之间互通。 (2)网络规划 根据用户需求，设计如图2-1所示网络拓扑图。 图2-1 静态路由配置举例组网图 2. 配置步骤 交换机上的配置步骤： # 设置以太网交换机Switch A的静态路由。
[SwitchB] ip route-static 1.1.1.0 255.255.255.0 1.1.3.1 # 设置以太网交换机Switch C的静态路由。
神州数码交换机路由器命令汇总(部分) 2016年3月23日星期三修改_________________________________________________________________________ 注：本文档命令为最简命令，如不懂请在机器上实验 注：交换机版本信息： DCRS-5650-28(R4) Device, Compiled on Aug 12 10:58:26 2013 sysLocation China CPU Mac 00:03:0f:24:a2:a7 Vlan MAC 00:03:0f:24:a2:a6 SoftWare Version 7.0.3.1(B0043.0003) BootRom Version 7.1.103 HardWare Version 2.0.1 CPLD Version N/A Serial No.:1 Copyright (C) 2001-2013 by Digital China Networks Limited. All rights reserved Last reboot is warm reset. Uptime is 0 weeks, 0 days, 1 hours, 42 minutes 路由器版本信息： Digital China Networks Limited Internetwork Operating System Software DCR-2659 Series Software, Version 1.3.3H (MIDDLE), RELEASE SOFTWARE Copyright 2012 by Digital China Networks(BeiJing) Limited Compiled: 2012-06-07 11:58:07 by system, Image text-base: 0x6004 ROM: System Bootstrap, Version 0.4.2 Serial num:8IRTJ610CA15000001, ID num:201404 System image file is "DCR-2659_1.3.3H.bin" Digital China-DCR-2659 (PowerPC) Processor 65536K bytes of memory,16384K bytes of flash Router uptime is 0:00:44:44, The current time: 2002-01-01 00:44:44 Slot 0: SCC Slot Port 0: 10/100Mbps full-duplex Ethernet Port 1: 2M full-duplex Serial Port 2: 2M full-duplex Serial Port 3: 1000Mbps full-duplex Ethernet Port 4: 1000Mbps full-duplex Ethernet Port 5: 1000Mbps full-duplex Ethernet Port 6: 1000Mbps full-duplex Ethernet
通过在外网口配置nat基本就OK了，以下配置假设Ethernet0/0为局域网接口，Ethernet0/1为外网口。 1、配置内网接口（E t h e r n e t0/0）：[M S R20-20]i n t e r f a c e E t h e r n e t0/0 [M S R20-20 2、使用动态分配地址的方式为局域网中的P C分配地址[M S R20-20]d h c p s e r v e r i p-p o o l 1 [M S R20-20-d h c p-p o o l-1]n e t w o r k2 4 [M S R20-20 [M S R20-20 3、配置n a t [M S R20-20]n a t a d d r e s s-g r o u p1公网I P公网I P [MSR20-20]acl number 3000 [MSR20-20-acl-adv-3000]rule 0 permit ip 4、配置外网接口（Ethernet0/1） [MSR20-20] interface Ethernet0/1 [MSR20-20- Ethernet0/1]ip add 公网IP [MSR20-20- Ethernet0/1] nat outbound 3000 address-group 1 5．加默缺省路由 [MSR20-20]route-stac 0.0.0外网网关 总结： 在2020路由器下面, 配置外网口, 配置内网口, 配置acl 作nat, 一条默认路由指向电信网关. ok! Console登陆认证功能的配置 关键词：MSR;console; 一、组网需求： 要求用户从console登录时输入已配置的用户名h3c和对应的口令h3c，用户名和口令正确才能登录成功。 二、组网图： 三、配置步骤：
第一部分交换机配置 一、基础配置 1、模式进入 Switch> Switch>en Switch#config Switch(Config)#interface ethernet 0/2 2、配置交换机主机名 命令：hostname <主机名> 3、配置交换机IP地址 Switch(Config)#interface vlan 1 Switch(Config-If-Vlan1)#ip address 10.1.128.251 255.255.255.0 Switch(Config-If-Vlan1)#no shut 4、为交换机设置Telnet授权用户和口令： 登录到Telnet的配置界面，需要输入正确的用户名和口令，否则交换机将拒绝该Telnet用户的访问。该项措施是为了保护交换机免受非授权用户的非法操作。若交换机没有设置授权Telnet用户，则任何用户都无法进入交换机的Telnet配置界面。因此在允许Telnet方式配置管理交换机时，必须在Console的全局配置模式下使用命令username
1．下列应用使用TCP连接的有（本题3项正确） A.Telnet B.BGP C.FTP D.TFTP 2．TCP和UDP协议的相似之处是 A.传输层协议 B.面向连接的协议 C.面向非连接的协议 D.其它三项均不对 3．下列应用使用UDP连接的有（本题3项正确） A.TFTP B.Syslog C.SNMP D.HTTP 4．第一个八位组以二进1110开头的IP地址是（）地址 A.Class A B.Class B C.Class C D.Class D 5．下面哪些不是ICMP提供的信息 A.目的地不可达 B.目标重定向 C.回声应答 D.源逆制 6．C类地址最大可能子网位数是 A.6 B.8 C.12 D.14 7．（）协议是一种基于广播的协议，主机通过它可以动态的发现对应于一个IP地址的MAC地址 A.ARP B.DNS C.ICMP D.RARP 8．IP地址为子网掩码为的地址，可以划分多少个子网位，多少个主机位 A.2，32 B.4，30 C.254，254 D.2，30 9．关于IPX的描述正确的是（本题3项正确） A.IPX地址总长度为80位，其中网络地址占48位，节点地址占32位 B.IPX地址总长度为80位，其中网络地址占32位，节点地址占48位
C.IPX是一个对应于OSI参考模型的第三层的可路由的协议 D.NCP属于应用层的协议，主要在工作站和服务器间建立连接，并在服务器和客户 机间传送请求和响应 10．在无盘工作站向服务器申请IP地址时，使用的是（）协议 A.ARP B.RARP C.BOOTP D.ICMP 11．以太网交换机的数据转发方式可以被设置为（本题2项正确） A.自动协商方式 B.存储转发方式 C.迂回方式 D.直通方式 12．当交换机检测到一个数据包携带的目的地址与源地址属于同一个端口时，交换机会怎样处理？ A.把数据转发到网络上的其他端口 B.不再把数据转发到其他端口 C.在两个端口间传送数据 D.在工作在不同协议的网络间传送数据 13．下面哪个标准描述了生成树协议 A. B. C. D. 14．下列有关端口隔离的描述正确的是：(本题2项正确) A.DCS-3726B出厂时即是端口隔离状态，所有端口都可以与第一个端口通信，但之 间不可以互通 B.DCS-3726S可以通过配置实现与3726B一样的端口隔离功能，但出厂默认不时隔 离状态 C.可以通过配置私有VLAN功能实现端口隔离 D.可以通过配置公用端口实现端口隔离 15．下列关于静态配置链路聚合和动态配置链路聚合的理解正确的是: A.静态配置链路聚合需要在聚合组的每个聚合端口中进行配置 B.动态配置链路聚合只需要在主端口中配置一次，在全局模式中配置启用lacp协 议即可 C.静态配置链路聚合不能进行负载均衡 D.动态配置链路聚合不需要配置聚合组号，交换机会根据目前聚合组的情况自动 指定 16．网络接口卡(NIC)可以做什么？ A.建立、管理、终止应用之间的会话，管理表示层实体之间的数据交换 B.在计算机之间建立网络通信机制 C.为应用进程提供服务 D.提供建立、维护、终止应用之间的会话，管理表示层实体之间的数据交换17．以下关于以太网交换机的说法哪些是正确的?
操作手册 IP路由分册 IPv6 静态路由目录 目录 第1章 IPv6静态路由配置......................................................................................................1-1 1.1 IPv6静态路由简介.............................................................................................................1-1 1.1.1 IPv6静态路由属性及功能........................................................................................1-1 1.1.2 IPv6缺省路由..........................................................................................................1-1 1.2 配置IPv6静态路由.............................................................................................................1-2 1.2.1 配置准备..................................................................................................................1-2 1.2.2 配置IPv6静态路由...................................................................................................1-2 1.3 IPv6静态路由显示和维护..................................................................................................1-2 1.4 IPv6静态路由典型配置举例（路由应用）.........................................................................1-3 1.5 IPv6静态路由典型配置举例（交换应用）.........................................................................1-5
路由 ssh aaa authentication login ssh local aaa authentication enable default enable enable password 0 123456 username admin password 0 123456 ip sshd enable ip sshd auth-method ssh ip sshd auth-retries 5 ip sshd timeout 60 TELNET R1_config#aaa authentication login default local R1_config#aaa authentication enable default enable R1_config#enable password 0 ruijie R1_config#line vty 0 4 R1_config_line#login authentication default R1_config_line#password 0 cisco 方法2，不需要经过3A认证 R1_config#aaa authentication login default none R1_config#aaa authentication enable default enable R1_config#enable password 0 cisco R1_config#line vty 0 4 R1_config_line#login authentication default CHAP认证单向认证，密码可以不一致 R2_config#aaa authentication ppp test local R2_config#username R2 password 0 123456 R2_config_s0/2#enc ppp R2_config_s0/2#ppp authentication chap test R2_config_s0/2#ppp chap hostname R1 R1_config#aaa authentication ppp test local R1_config#username R1 password 0 123456 R1_config_s0/1#enc ppp R1_config_s0/1#ppp authentication chap test R1_config_s0/1#ppp chap hostname R2
1. 基本配置： 开启SSH服务：debug ssh-server 设置特权模式密码：enable password [8]
10级网络设备常规实训【router】文档 -2011-2012学年第一学期- 实训老师：沈广东刘海涛 编辑：蒋立彪沈广东 目录 一、路由器基本配置-------------------------------------------03 二、使用访问控制列表（ACL）过滤网络数据包-------06 三、路由器的NAT功能--------------------------------------08 四、路由器DHCP 配置--------------------------------------10 五、本地局域网互联（路由协议配置）------------------14 六、使用DCVG-204实现VOIP ---------------------------19 七、跨路由使用DCVG-204---------------------------------22
一、路由器基本配置 一、试验目的： 1．掌握路由器本地设置的方法。 2．掌握路由器设置命令。（设置端口IP） 3．掌握路由器远程设置的方法。（telnet 服务） 二、试验设备 1．DCR-1700路由器1台 2．Console 线、直通双绞线 3．DCRS-3926S交换机1台 三、试验拓扑结构 ：192.168.1.2/24 192.168.1.254 线 //思考1：如果路由器要直接和PC连接，是用直通线？还是交叉线？ 三、实验任务及步骤 １.Console 口连接 ２.任务模式：enable 特权配置模式 Config 全局配置模式 ３.测试计算机与路由器的连通性 PC机配置： Route 配置： Router#delete this file will be erased,are you sure?(y/n)y no such file Router#reboot Do you want to reboot the router(y/n)? //恢复出厂设置并重启 Router_config#hostname RouterA RouterA _config# //修改主机名 RouterA _config#interface fastEthernet 0/0 （//进入100M端口，） //思考2：若想进入10M口如何？ // RouterA _config#interface ethernet 0/1 进入10M口
ICT企业网关H3C路由器配置实例 以下是拱墅检查院企业网关的配置实例。路由器是选H3C MRS20-10（ICG2000），具体配置的内容是： PPP+DHCP+NAT+WLAN [H3C-Ethernet0/2] # version 5.20, Beta 1605 # sysname H3C # domain default enable system # dialer-rule 1 ip permit # vlan 1 # domain system access-limit disable state active idle-cut disable self-service-url disable
# dhcp server ip-pool 1 network 192.168.1.0 mask 255.255.255.0 gateway-list 192.168.1.1 dns-list 202.101.172.35 202.101.172.46 # acl number 2001 rule 1 permit source 192.168.1.0 0.0.0.255 # wlan service-template 1 crypto ssid h3c-gsjcy authentication-method open-system cipher-suite wep40 wep default-key 1 wep40 pass-phrase 23456 service-template enable # wlan rrm 11a mandatory-rate 6 12 24 11a supported-rate 9 18 36 48 54 11b mandatory-rate 1 2 11b supported-rate 5.5 11 11g mandatory-rate 1 2 5.5 11
version 5.20, Release 2104P02, Basic # sysname H3C # nat address-group 27 122.100.84.202 122.100.84.202 # # domain default enable system # dns resolve dns proxy enable # telnet server enable # dar p2p signature-file cfa0:/p2p_default.mtd # port-security enable # # vlan 1 # domain system access-limit disable state active idle-cut disable self-service-url disable # dhcp server ip-pool 1 network 192.168.201.0 mask 255.255.255.0 gateway-list 192.168.201.1 dns-list 202.106.0.20 202.106.46.151 # # user-group system # local-user admin password cipher .]@USE=*8 authorization-attribute level 3 service-type telnet # interface Aux0 async mode flow link-protocol ppp
interface Cellular0/0 async mode protocol link-protocol ppp # interface Ethernet0/0 port link-mode route nat outbound address-group 27 ip address 122.100.84.202 255.255.255.202 # interface Ethernet0/1 port link-mode route ip address 192.168.201.1 255.255.255.0 # interface NULL0 # # ip route-static 0.0.0.0 0.0.0.0 122.100.84.201 # dhcp enable # load xml-configuration # user-interface con 0 user-interface tty 13 user-interface aux 0 user-interface vty 0 4 authentication-mode scheme user privilege level 3 set authentication password simple###￥￥￥# return [H3C]
神州数码交换机基本配置 恢复交换机的出厂设置 命令：set default 功能：恢复交换机的出厂设置。 命令模式：特权用户配置模式。 使用指南：恢复交换机的出厂设置，即用户对交换机做的所有配置都消失，用户重新启动交换机后，出现的提示与交换机首次上电一样。 注意：配置本命令后，必须执行write 命令，进行配置保留后重启交换机即可使交换机恢复到出厂设置。 举例： Switch#set default Are you sure? [Y/N] = y Switch#write Switch#reload 进入交换机的Setup配置模式 命令：setup 功能：进入交换机的Setup配置模式。 命令模式：特权用户配置模式。 使用指南：在Setup配置模式下用户可进行IP地址、Web 服务等的配置。 举例： Switch#setup Setup Configuration ---System Configuration Dialog--- At any point you may enter Ctrl+C to exit. Default settings are in square brackets [ ]. If you don't want to change the default settings, you can input enter. Continue with configuration dialog? [y/n]:y Please select language [0]:English [1]:中文 Selection(0|1) [0]:0 Configure menu [0]:Config hostname [1]:Config interface-Vlan1 [2]:Config telnet-server [3]:Config web-server [4]:Config SNMP [5]:Exit setup configuration without saving [6]:Exit setup configuration after saving
山石网科SG/神州数码DCFW-1800系列安全网关至中神通UTMWALL的功能迁移手册 更多产品迁移说明： 山石网科安全网关是Hillstone针对中小企业及分支机构用户的安全现状和需求推出的全新高性能多核安全网关。产品采用业界领先的多核Plus G2安全架构和64位实时安全操作系统StoneOS?，提供全方位的安全防护、易用的可视化管理和卓越的性能，为中小企业和分支机构用户提供高性价比的全面安全解决方案。山石网科下一代智能防火墙采用创新的主动检测技术和智能多维处理架构，通过全网健康指数帮助用户实时掌握安全状况；基于先进的应用识别和用户识别技术，为用户提供高性能应用层安全防护及增强的智能流量管理功能。 神州数码DCFW-1800系列防火墙是神州数码网络有限公司自主开发、拥有知识产权的新一代高性能纯硬件网络安全产品，能够为大中型企业、政府机关、教育机构等的网络安全问题提供安全高速的解决方案。DCFW-1800系列防火墙拥有集成的网络安全硬件平台，采用专有的实时操作系统，可以灵活的划分安全域，并且可以自定义其它安全级别的域，防火墙的安全策略规则会对信息流进行检查和处理，从而保证网络的安全。 武汉中神通信息技术有限公司历经15年的开发和用户使用形成了中神通UTMWALL?系列产品，有硬件整机、OS软件、虚拟化云网关等三种产品形式，OS 由50多个不断增长的功能APP、32种内置日志和5种特征库组成，每个APP都有配套的在线帮助、任务向导、视频演示和状态统计，可以担当安全网关、防火墙、UTM、NGFW等角色，胜任局域网接入、服务器接入、远程VPN接入、流控审计、行为管理、安全防护等重任，具备稳定、易用、全面、节能、自主性高、扩展性好、性价比优的特点，是云计算时代的网络安全产品。 以下是两者之间的功能对比迁移表： 山石网科SG v5.0功能项页码中神通UTMWALL v1.8功能项页码第1章产品概述 1 A功能简介8 第2章搭建配置环境 6 B快速安装指南9 第3章命令行接口（CLI）10 B快速安装指南9 第4章系统管理15 2系统管理47
神州数码交换机配置基本命令 交换机基本状态： hostname> ；用户模式 hostname# ；特权模式 hostname(config)# ；全局配置模式 hostname(config-if)# ；接口状态 交换机口令设置： switch>enable ；进入特权模式 switch#config terminal ；进入全局配置模式 switch(config)#hostname ；设置交换机的主机名 switch(config)#enable secret xxx ；设置特权加密口令 switch(config)#enable password xxa ；设置特权非密口令 switch(config)#line console 0 ；进入控制台口 switch(config-line)#line vty 0 4 ；进入虚拟终端 switch(config-line)#login ；允许登录 switch(config-line)#password xx ；设置登录口令xx switch#exit ；返回命令 交换机VLAN设置： switch#vlan database ；进入VLAN设置 switch(vlan)#vlan 2 ；建VLAN 2 switch(vlan)#no vlan 2 ；删vlan 2 switch(config)#int f0/1 ；进入端口1 switch(config-if)#switchport access vlan 2 ；当前端口加入vlan 2 switch(config-if)#switchport mode trunk ；设置为干线 switch(config-if)#switchport trunk allowed vlan 1，2 ；设置允许的vlan switch(config-if)#switchport trunk encap dot1q ；设置vlan 中继switch(config)#vtp domain ；设置发vtp域名 switch(config)#vtp password ；设置发vtp密码 switch(config)#vtp mode server ；设置发vtp模式 switch(config)#vtp mode client ；设置发vtp模式 交换机设置IP地址： switch(config)#interface vlan 1 ；进入vlan 1 switch(config-if)#ip address ；设置IP地址 switch(config)#ip default-gateway ；设置默认网关 switch#dir Flash: ；查看闪存 交换机显示命令： switch#write ；保存配置信息 switch#show vtp ；查看vtp配置信息 switch#show run ；查看当前配置信息 switch#show vlan ；查看vlan配置信息 switch#show interface ；查看端口信息 switch#show int f0/0 ；查看指定端口信息 完了最最要的一步。要记得保存设置俄，
一、路由器工作模式： 用户模式：Router> 特权模式：Router # 全局配置模式：Router (config)# 接口配置模式：Router (config-if)# 路由配置模式：Router(config-router)# Line配置模式：Router(config-line)# 二、路由器口令设置： Router>enable；进入特权模式 Router#configterminal；进入全局配置模式 Router(config)#hostname xxx；设置路由器的主机名 Router(config)#enable secret level 15 0 xxx ；设置特权明文加密口令xxx Router (config)#enable password xxx；设置特权非密口令 Router(config)#line console 0；进入控制台口 Router(config-line)#line vty 0 4；进入虚拟终端 Router(config-line)#login；允许登录 Router(config-line)#password xx ；设置登录口令xx Router#exit；返回命令 三、路由器VLAN设置： 配置WAN接口 选择接口：Router(config)#i nterface s0/0/0 配置IP地址Router(config-if)#ip address 192.168.10.1 255.255.255.0 设置时钟频率：Router(config-if)#clock rate 64000（另一端无需配置）启用端口：Router(config-if)#no shutdown 四、路由协议设置： 静态路由：Router(config)#ip route network 目标网络网络掩码下一跳IP Router(config)#ip route 192.168.1.0 255.255.255.0 10.1.1.1 默认路由：Router(config)#ip route 0.0.0.0 0.0.0.0 10.1.1.1
大型企业网络防火墙解决方案 神州数码大型企业网络防火墙整体解决方案，在大型企业网络中心采用神州数码 DCFW-1800E防火墙以满足网络中心对防火墙高性能、高流量、高安全性的需求，在各分支机构和分公司采用神州数码DCFW-1800S防火墙在满足需要的基础上为用户节约投资成本。另一方面，神州数码DCFW-1800系列防火墙还内置了VPN功能，可以实现利用Internet构建企业的虚拟专用网络。 防火墙VPN解决方案 作为增值模块，神州数码DCFW-1800防火墙内置了VPN模块支持，既可以利用因特网（Internet）IPSEC通道为用户提供具有保密性，安全性，低成本，配置简单等特性的虚拟专网服务，也可以为移动的用户提供一个安全访问公司内部资源的途径，通过对PPTP协议的支持，用户可以从外部虚拟拨号，从而进入公司内部网络。神州数码DCFW-1800系列防火墙的虚拟专网具备以下特性： 标准的IPSEC,IKE与PPTP协议
支持Gateway-to-Gateway网关至网关模式虚拟专网 支持VPN的星形（star）连接方式 VPN隧道的NAT穿越 支持IP与非IP协议通过VPN 支持手工密钥，预共享密钥与X.509 V3数字证书,PKI体系支持IPSEC安全策略的灵活启用：管理员可以根据自己的实际需要，手工禁止和启用单条IPSEC安全策略，也为用户提供了更大的方便。 支持密钥生存周期可定制 支持完美前项保密 支持多种加密与认证算法： 加密算法：DES, 3DES,AES,CAST,BLF，PAP，CHAP 认证算法：SHA, MD5, Rmd160 支持Client-to-Gateway移动用户模式虚拟专网 支持PPTP定制：管理员可以根据自己的实际需要，手工禁止和启用PPTP。