CHAPTER 8: DYNAMIC HOST CONFIGURATION PROTOCOL SUPPORT Trần Giáo_Khoa CNTT_ĐH Thái Nguyên 1 Chương 8: Dynamic Host Configuration Protocol Support HỖ TRỢ GIAO THỨC CẤU HÌNH HOST ĐỘNG (DHCP) Tổng quan: Chương này bao gồm các topic sau: Mục tiêu Giao thức cấu hình host động PIX Firewall là một server DHCP PIX Firewall là một client DHCP Tổng hợp Lab excersice Tổng tiêu: CHAPTER 8: DYNAMIC HOST CONFIGURATION PROTOCOL SUPPORT Trần Giáo_Khoa CNTT_ĐH Thái Nguyên 2 GIAO THỨC CẤU HÌNH HOST ĐỘNG (DHCP) Phần này sẽ mô tả chức năng của giao thức cấu hình host động (DHCP) và giải thích cách thức PIX Firewall sử dụng nó như thế nào. DHCP cung cấp khả năng tự động cấp phát địa chỉ mạng (có thể sử dụng lại được) trên một mạng TCP/IP. Điều này tạo sự dẽ dàng cho người quản trị và làm giảm đáng kể những lỗi do con người gây ra. Không có DHCP thì một địa chỉ IP cần phải được nhập bằng tay cho mỗi một máy tính hoặc thiết bị mà yêu cầu địa chỉ IP DHCP cũng có thể. DHCP cũng có thể cấp phát những tham số cấu hình khác như là địa chỉ server DNS ,WINS và domain names (tên miền). Host cấp phát địa chỉ và các tham số cấu hình cho DHCP clients gọi là DHCP server. Một DHCP client là bất kỳ host nào sử dụng DHCP để lấy các tham số cấu hình Lưu lương DHCP bao gồm các gói tin quảng bá của router để điều khiển sự gia tăng không cần thiết của các gói tin quảng bá, nó có thể là cần thiết để cho phép đẩy các gói tin quảng bá DHCP trên router giữa DHCP server và clients của nó. Để có phần mềm CISCO IOS đẩy những gói tin quảng bá này, sử dụng lệnh cấu hình giao diện ip helper-address. Địa chỉ được chỉ định trong lệnh này sẽ là DHCP server. CHAPTER 8: DYNAMIC HOST CONFIGURATION PROTOCOL SUPPORT Trần Giáo_Khoa CNTT_ĐH Thái Nguyên 3 Bất kỳ PIX Firewall nào mà chạy phiên bản 5.2 hoặc cao hơn đều hỗ trợ DHCP server và client. Một DHCP server là một thiết bị cung cấp các tham số cấu hình cho một DHCP client, và một DHCP client là một thiết bị sử dụng DHCP để lấy các tham số cấu hình mạng Trong một môi trường mạng được đảm bảo an ninh bởi PIX Firewall, PC clients kết nối đến PIX Firewall và thiết lập kết nối mạng để truy cập một mạng doanh nghiệp hoặc tập đoàn. Như là một DHCP server, PIX Firewall cung cấp cho những PC này (là DHCP client của nó) những tham số mạng cần thiết để truy cập tới mạng của doanh nghiệp hay tổ chức., và một mạng inside. PIX Firewall cung cấp các dịch vị mạng để sử dụng như là DNS server. Giống như DHCP clients, PIX Firewall có thể lấy một địa chỉ IP, subnet mask, các tùy chọn và một tuyến đường mặc định từ một DHCP server Note: hiện tại PIX Firewall có thể cấp phát các tham số cấu hình chỉ đến các clients mà kết nối vật lý đến mạng con của inside interface của PIX Firewall. CHAPTER 8: DYNAMIC HOST CONFIGURATION PROTOCOL SUPPORT Trần Giáo_Khoa CNTT_ĐH Thái Nguyên 4 The PIX Firewall as a DHCP Server Phần này sẽ giải thích cách cấu hình PIX Firewall để hoạt động như là một DHCP Server Truyền thông DHCP bao gồm một vài thông điệp được truyền qua giữa DHCP client và DHCP server. Dưới đây là các sự kiện sẽ xảy ra trong quá trình trao đổi này: 1. Client broadcast (quảng bá) một thông điệp DHCPDISCOVER trên cổng vật lý cục bộ đến DHCP server 2. Bất kỳ DHCP server nào nhận được thông điệp đó có thể đáp ứng với một thông điệp DHCPOFFER, thông điệp này bao gồm một địa chỉ mạng (địa chỉ phải tồn tại) và một vài tham số cấu hình khác 3. Dựa trên các tham số cấu hình được đưa ra trong thông điệp DHCPOFFER. Client chọn một server để yêu cầu các tham số cấu hình. Client quảng bá một thông điệp DHCPREQUEST yêu cầu đưa ra các tham số từ một server và hủy thông điệp từ tất cả các server khác 4. Server chọn trong thông điệp DHCPREQUEST đáp ứng với một thông điệp DHCPACK chưa các tham số cấu hình cho yêu cầu của Crime and the Law Crime and the Law Bởi: OpenStaxCollege How is a crime different from other types of deviance? (Photo courtesy of Duffman/Wikimedia Commons.) On December 16, 2011, 20-year-old Colton Harris-Moore was sentenced to seven years in prison by an Island County judge after pleading guilty to dozens of charges including burglary, fraud, and identity theft Harris-Moore, dubbed the “Barefoot Bandit,” spent two years evading the police by means of transportation theft and squatting, frequently leaving a trail of bare footprints in his wake (Johnson 2011) "Colton's very pleased (with the sentence)," his attorney John Henry Browne told the New York Times "He was expecting the worst." The son of an alcoholic mother, Harris-Moore’s life was filled with physical and verbal abuse, and a series of convict boyfriends frequently inhabited the Harris-Moore home After dropping out of school in the ninth grade, Harris Moore’s crimes increased in severity His antics gained worldwide media attention after he began stealing and successfully piloting planes, though he’d had no aviation training When authorities caught him, he was driving a stolen boat off the coast of the Bahamas (Yardley 2010) "This case is a tragedy in many ways,” said Judge Churchill, “but it's a triumph of the human spirit in other ways I could have been reading about the history of a mass murderer I could have been reading about a drug abusive, alcoholic young man That is the triumph of Colton Harris-Moore: He has survived" (Johnson 2011) 1/10 Crime and the Law Though the judge’s ruling was largely sympathetic, Harris-Moore had immediate regrets "Let me put it this way,” said his attorney “He wishes he had done things a little differently in his life" (CNN News Wire Staff 2010) Although deviance is a violation of social norms, it’s not always punishable, and it’s not necessarily bad Crime, on the other hand, is a behavior that violates official law and is punishable through formal sanctions Walking to class backwards is a deviant behavior Driving with a blood alcohol percentage over the state’s limit is a crime Like other forms of deviance, however, ambiguity exists concerning what constitutes a crime and whether all crimes are, in fact, “bad” and deserve punishment For example, during the 1960s, civil rights activists often violated laws intentionally as part of their effort to bring about racial equality In hindsight, we recognize that the laws that deemed many of their actions crimes—for instance, Rosa Parks taking a seat in the “whites only” section of the bus—were inconsistent with social equality As you learned previously, all societies have informal and formal ways of maintaining social control Within these systems of norms, societies have legal codes that maintain formal social control through laws, which are rules adopted and enforced by a political authority Those who violate these rules incur negative formal sanctions Normally, punishments are relative to the degree of the crime and the importance to society of the value underlying the law As we will see, however, there are other factors that influence criminal sentencing Types of Crimes Not all crimes are given equal weight Society generally socializes its members to view certain crimes as more severe than others For example, most people would consider murdering someone to be far worse than stealing a wallet and would expect a murderer to be punished more severely than a thief In modern American society, crimes are classified as one of two types based on their severity Violent crimes (also known as “crimes against a person”) are based on the use of force or the threat of force Rape, murder, and armed robbery fall under this category Nonviolent crimes involve the destruction or theft of property, but not use force or the threat of force Because of this, they are also sometimes called “property crimes.” Larceny, car theft, and vandalism are all types of nonviolent crimes If you use a crowbar to break into a car, you are committing a nonviolent crime; if you mug someone with the crowbar, you are committing a violent crime When we think of crime, we often picture street crime, or offenses committed by ordinary people against other people or organizations, usually in public spaces An often overlooked category is corporate crime, or crime committed by white-collar workers in a business environment Embezzlement, insider trading, and identity theft are all types of corporate crime Although these types of offenses rarely receive the same amount of 2/10 Crime and the Law media coverage as street crimes, they can be far more damaging The current economic recession in the United States is the ultimate result of a financial collapse triggered by corporate crime An often-debated third type of crime is victimless crime These are called victimless because the perpetrator is not explicitly harming another person As opposed to battery or theft, which clearly have a victim, a crime like drinking a beer ... © SANS Institute 2004, Author retains full rights. Key fingerprint = AF19 FA27 2F94 998D FDB5 DE3D F8B5 06E4 A169 4E46 © SANS Institute 2004, As part of the Information Security Reading Room Author retains full rights. OpenVPN and the SSL VPN Revolution Charlie Hosner 8.8.2004 GSEC v.1.4b © SANS Institute 2004, Author retains full rights. Key fingerprint = AF19 FA27 2F94 998D FDB5 DE3D F8B5 06E4 A169 4E46 © SANS Institute 2004, As part of the Information Security Reading Room Author retains full rights. TABLE OF CONTENTS INTRODUCTION 3 QUICK INTRO TO CRYPTOGRAPHY . 5 Symmetric Ciphers – Confidentiality 5 Message Digests – Integrity 5 Asymmetric Ciphers – Everything Else . 6 VPN IN A NUTSHELL 7 WHAT THE HECK IS IPSEC? 7 SO HOW DO THESE THINGS WORK? 9 SSL/TLS TO THE RESCUE . 11 OPENVPN INSTALLATION . 12 OPENVPN CONFIGURATION . 13 User nobody 14 chroot the server . 14 TLS-auth 15 Adjust the MTU . 15 Route . 15 OPENVPN FEATURES 16 Throughput/Performance 16 NAT Traversal . 16 X509 Authentication 17 Ease of Configuration . 17 Load Balancing . 17 Failover . 18 Central Management 18 OPENVPN SECURITY . 18 Key Generation . 18 Key Derivation/Exchange . 19 Symmetric Ciphers 21 HMAC/Hashing 23 Additional OpenVPN Add-ons 25 OPENVPN FUTURE . 25 Single UDP port, config file and TUN interface . 25 Pseudo DHCP improvements 25 OTHER SSL VPNS 26 The Four Horsemen of SSL VPNs . 26 Security Issues . 28 CONCLUSION . 30 GLOSSARY 31 WORK CITED . 35 BIBLIOGRAPHY [...]... of a stock or option if it were traded on the open market Overhang: The percentage of the company’s stock that is devoted to options The calculation is the number of options granted and outstanding, plus the number of shares reserved for future grants divided by the number of shares outstanding Restricted Shares: 5 Fair Market Value: These are shares of stock granted to an employee While they are officially... see stock options as symptomatic of executive greed On the contrary greed and the desire to amass “more” are not only inevitable, they are also necessary components of the capitalist system Execu- FIGURE 1-1 What Are Employee Stock Options? Stock Options: The right to purchase a share of stock for a specific price, for a specified period of time Most options granted to employees give the employee the. .. source of capital But that capital is used in pursuit of the company’s actual purpose: to produce goods and services and sell them in the market Volcker: That’s right The purpose of the company is really to provide goods and services at the best possible price, at the highest level of productivity, and in a way that serves society and communities That is the purpose of the company The stock is just the. .. companies and top executives to reap shortterm wealth instead of focusing on sustained performance and enduring results STOCK OPTIONS AND CORPORATE CULTURE When stock options particularly large amounts of them— are offered to executives as incentives, the corporate culture is potentially impacted While stock options do not create the corporate culture of high-risk behavior, they do contribute to it In a corporate. .. Options Good: Options for start-ups and other cash-strapped companies; options that vest based on performance; options with exercise prices that vary with the market OK: Fixed-price options as part of a mix of performance-based incentives and/ or required stock ownership Bad: Fixed-price options for large, established public companies Ugly: Mega grants of fixed-price options to executives of large, established... exercises his options from the mega grant, he will make $1.12 million This profit would be in addition to the options he normally receives annually on $2 million to $3 million in stock CHAPTER ONE Dimensions of the Problem 9 EXECUTIVE WEALTH AND THE POSITIVE POWER OF GREED News stories have illustrated the magnitude of the wealth that executives can reap through the receipt of stock options In the New York... about stock price I don’t sell FOREWORD stock I don’t go to the market for new capital ever There are a lot more [...]... Rights and Fundamental Freedoms European Court of Justice European Court Reports European Coal and Steel Community European Economic Area European Economic Community European Free Trade Area Economic and Monetary Union European Union European University Institute Grand National Assembly (in Bulgaria) Intergovernmental Conference Irish Reports North Atlantic Treaty Organisation Of cial Journal of the European... dispute over who is the ultimate judicial arbiter in the EU – the European Court of Justice (ECJ) or the national constitutional courts The final chapter undertakes an analysis of the broader implications of the European Constitution for national constitutions and sovereignty The European Constitution will be assessed in the light of constitutional boundaries set to European integration by the highest national... Constitution The book is divided into ten chapters It starts by outlining the background of the enlargement process Chapter 2 explores the experience of the ‘old’ Member States in adapting their constitutions to the demands of EU membership, in order to provide a point of reference to the developments in the accession countries Chapter 3 highlights some idiosyncrasies of the new constitutions of Central and Eastern. .. explores the amendments against the background of comparative experience and theory of sovereignty, as well as in the context of political sensitivities, such as rising euroscepticism ahead of accession referendums It also undertakes a broader inquiry into the role and rationale of the national constitutions in the process of European integration, as well as exploring the implications of the European... 54 European Parliament’s Resolution of 1997 on the Abolition of the Death Penalty 54 Framework decision on the European Arrest Warrant 75, 93 Laeken Declaration 179 Protocol on the application of the principles of subsidiarity and proportionality 194 Protocol on the role of national Parliaments in the European Union 194 Provisional Consolidated Version of the Treaty Establishing a Constitution for Europe. .. enlargement special is that the acceding countries regained their sovereignty only a little more than a decade ago In response to a painful past, the new constitutions of Central and Eastern Europe accord a prominent status to sovereignty and independence, and were notably closed to the transfer of powers to international organisations In order to join the European Union (EU) , these constitutions therefore... the constitutional theory in Central and Eastern Europe has been underpinned by the traditional paradigm of sovereign nation-state, and the EU has until recently been portrayed as an international organisation Concluding that as a result of the above factors, the amendments in the CEE constitutions remained relatively minimal, the final part of chapter 5 discusses how this relates to the rationale of. .. 2004) 180 Treaty of Amsterdam 177, 186, 188–9, 196 Treaty of Nice 7, 179, This page intentionally left blank Imperialism, Sovereignty and the Making of International Law This book examines the relationship between imperialism and international law. It argues that colonial confrontation was central to theformation of international law and, in particular, its founding concept, sovereignty. Traditional histories of the discipline present colonialism and non-European peoples as peripheral concerns. By contrast, Anghie argues that international law has always been animated by the ‘civilizing mission’ the project of governing non-European peoples. Racial discrimination, cultural subordination and economic exploitation are constitutively significant for the discipline, rather than aberrations that have been overcome by modern international law. In developing these arguments, the book examines different phases of the colonial encounter, ranging from the sixteenth century to the League of Nations period and the current ‘war against terror’. Anghie provides a new approach to the history of international law, illuminating the imperial character of the discipline and its enduring significance for peoples of the Third World. antony anghie is Professor of Law at the S. J. Quinney School of Law, University of Utah. He received his LLB (Hons.) and BA (Hons.) degrees from Monash University, Melbourne, Australia, and his SJD degree from Harvard Law School. He practised law for several years in Melbourne, and now teaches Contracts and various subjects in the International Law curriculum, including International Business Transactions and International Environmental Law. He has served as a tutor at Monash and Melbourne Universities, where he has taught Development Politics and International Relations; and as a Teaching Fellow at Harvard College where he has taught International Relations. He also served as Senior Fellow at Harvard Law School and a Visiting Professor at the University of Tokyo. He is a member of the Third World Approaches to International Law network of scholars. c ambridge studies in international and comparative law Established in 1946, this series produces high-quality scholarship in the fields of public and private international law and comparative law. Although these are distinct legal subdisciplines, developments since 1946 confirm their interrelation. Comparative law is increasingly used as a tool in the making of law at national, regional and international levels. Private international law is now often affected by international conventions, and the issues faced by classical conflicts rules are frequently dealt with by substantive harmonisation of law under international auspices. Mixed international arbitrations, especially those involving state economic activity, raise mixed questions of public and private international law, while in many fields (such as the protection of human rights and democratic standards, investment guarantees and international criminal law) international and national systems interact. National constitutional arrangements relating to ‘foreign affairs’, and to the implementation of international norms, are a focus of attention. The Board welcomes works of a theoretical or interdisciplinary character, and those focusing on the new approaches to international or comparative law or conflicts of law. Studies of particular institutions or ... crime from more detailed perspectives 4/10 Crime and the Law and to analyze the data based on factors such as the relationship between victims and offenders, the consequences of the crimes, and. .. relative to the degree of the crime and the importance to society of the value underlying the law As we will see, however, there are other factors that influence criminal sentencing Types of Crimes... rarely receive the same amount of 2/10 Crime and the Law media coverage as street crimes, they can be far more damaging The current economic recession in the United States is the ultimate result