internet security protocols - gbv.de
TRANSCRIPT
Internet Security Protocols
Protecting IP Traffic
UYLESS BLACK
Prentice Hall PTR Upper Saddle River, New Jersey 07458
www. phptr. com
Contents
PREFACE XVII
CHAPTER 1 Introduction
Security Problems 1 How Pervasive Are Security Attacks? 2 Types of Security Services 4 Introduction to the Firewall 5 The Security Policy 6
Trusted and Untrusted Networks 6 Security and Risk Management 7 Virtual Private Networks (VPNs) 7
The Modern VPN 8 VPNs and SLAs 11 The Debate of Privacy vs. Law Enforcement 12
CHAPTER 2 Types of Security Violations 15
Types of Security Problems 15 Denial of Service: Attacks and Counter-attacks 15
Virus 16
vii
Worm 17 Clogging or Flooding 18 Trojan Horse 18 Bomb 18 Trap Door 19 Salami 20 Replay Violations 20 Cookies 20 Applets and Sandboxes 22 Other Problems 24 Summary 24
CHAPTER 3 Basic Security Concepts 25
How Secure is Secure? 26 Definitions 26
Encryption and Decryption 26 Basic Encryption and Decryption Methods 27
The German Enigma Machine 29 Substitution and Transposition 30 One-way Functions and Modular Arithmetic 30
Example of a One-way Function 32 The Diffie-Hellman Idea Using
Modular Arithmetic 32 The Hash Function 33 Use of a One-way Hash Function 35 Randomness of Keys 35
Randomness or Lack Thereof Equals the Demise of a Crypto System 36
Key Problem: Exchanging Keys 37 Awkwardness of Key Distribution 38
The Asymmetric Key 39 Use of the Asymmetric Keys in Reverse Order 39 Asymmetric Keys for Privacy 40 Asymmetric Keys for Authentication:
The Digital Signature 41 The Next Step: RSA 42
The RSA Key Pairs 43 Key Transport and Key Generation 45 Message Authentication Code (MAC) and Key Hashing 45 Putting Together the Security Functions 46
CONTENTS ix
Paul Zimmerman and Pretty Good Privacy (PGP) 49 PGP's Use of Key Certificates 50 Example of a PGP Public Key 50 OpenPGP 51
Perfect Forward Secrecy (PFS) 52 Man-in-the-Middle Attack 52 Certification 54 The Certification Procedure 55 Anti-Replay Measures 55 Security in a Mobile Network 57
Authentication 57 Privacy Operations 58
Summary 59
CHAPTER 4 Firewalls 60
What is a Firewall? 60 Protection from Untrusted Networks 61
Permitting and Denying Services 62 What Firewalls Can Do and Cannot Do 62 Packet Filtering 64 Proxy or Application Firewalls 65 NCSA Guidance 66 Managed Firewall Services (MFWS) 67
Evaluating a Firewall Service Provider 69 Firewalls with Internet Security Protocols (IPSec) 70 SOCKS 71 Summary 71
CHAPTER 5 Prominent Internet Security Procedures 72
Diffie-Hellman 73 Diffie-Hellman and RFC 2631 74
Rivest, Shamir, and Adleman (RSA) 76 RSA in RFC 2437 76
MD5 78 MD5 Vulnerabilities? 81
RFC 2537: RSA, MD5, and DNS 81 RSA Public KEY Resource Records 81 RSA/MD5 SIG Resource Records 82 Performance Considerations 82
The Secure Hash Standard (SHA-1) and The Secure Hash Algorithm (SHA) 83
RIPEMD-160 83 Comparisons of MD5, SHA-1, RIPEMD-160,
and MD5-HMAC 83 HMAC 84 Performance and Security of HMAC 86 HMAC with IPSec 87 The OAKLEY Key Determination Protocol 87
Beyond Diffie-Hellman and STS 88 OAKLEY Key Exchange Processing 89 The Essential Key Exchange Message Fields 89
Summary 90
CHAPTER 6 PPP, ECP, TLS, EAP, DESE-bis, and 3DESE 91
PPP and HDLC 91 LCP 93 General Example of PPP Operations 94 PPP Phase Diagram 94
Link Dead (Physical Layer Not Ready) 95 Link Establishment Phase 96 Authentication Phase 96 Network Layer Protocol Phase 96 Link Termination Phase 96
LCP Packets 97 Configure-Request 98 Configure-Ack 98 Configure-Nak 98 Configure-Reject 99 Terminate-Request and Terminate-Ack 99 Code-Reject 99 Protocol-Reject 99 Echo-Request and Echo-Reply 99 Discard-Request 99
Other Supporting Cast Members for PPP Security Services 100
Transport Layer Security Protocol (TLS) 100 Goals of TLS 100
PPP Encryption Control Protocol (ECP) 101 PPP Extensible Authentication Protocol (EAP) 102
CONTENTS XI
PPP DES Encryption Protocol, Version 2 (DESE-bis) 103 Configuration Option for ECP 104 Packet Format for DESE 104
PPP Triple-DES Encryption Protocol (3DESE) 105 The Algorithm 105 Keys 106 3DESE Configuration Option for ECP 106 Packet Format for 3DESE 107
Summary 108
CHAPTER 7 Dial-in Operations with PAP, CHAP, RADIUS and DIAMETER 109
PAP and CHAP 109 PAP 109 Key Aspects of PAP 110
CHAP 111 CHAP Messages 111
RADIUS 113 RADIUS Configuration 114
Example of a RADIUS Message Exchange 115 UseofUDP 116 RADIUS Message Format 117 RADIUS Attributes 118 Examples of RADIUS Operations 120 Problems with RADIUS 121
DIAMETER 122 DIAMETER Message Formats 122
Message Header 122 Message Body for the AVP 123 DIAMETER-Command AVP 124 Message-Reject-Ind Command 125 Approach to the Remainder of Message
Descriptions 125 Basic Operations 129 DIAMETER Support of Dial-Ins To/From SS7 131
Session Setup Messages Signaling Gateway/ NAS Controller Interaction 131
Message Exchanges Examples 133 Summary 136
xii
CHAPTER 8 IPSec Architecture 137
Basics of IPSec 137 IPSec Services 138 IPSec Traffic Security Protocols 138 Security Association (SA) Databases 138 The IPSec Tunnel 139
The Security Association (SA) 139 Cases of Security Associations: A General View 141
Types of SAs: Transport Mode and Tunnel Mode 142 Combining Security Associations:
A More Detailed View 145 Placements of IPSec 147 The IPSec Databases 148 Selectors and SAD/SPD Operations 148
Destination IP Address 149 Source IP Address 149 Name 149 Transport Layer Protocol 149 Source and Destination Ports 150 Selectors and SAD/SPD Entries 150 Looking Up the SA in the SAD 150
Examples of IPSec Sending and Receiving Operations 151 Selecting and Using an SA or SA Bundle 155 Summary 156
CHAPTER 9 The IPSec AH and ESP Protocols 157
Services of the IPSec Protocols 157 Integrity Check Value (ICV) 158
Relationships of AH, ESP, and the Transport and Tunnel Modes 159
Handling Mutable Fields 159 Protection Coverage of the AH and ESP Packets 161
AH Protection 161 Services and Operations of AH 163
RFC 1826 163 RFC 2402 163 Integrity Check Value (ICV) for Outbound Packets 164 Integrity Check Value (ICV) for Inbound Packets 165
CONTENTS
Services and Operations of ESP 165 ESP Protection 165 RFC 1827 167 RFC 2406 168 Outbound Packet Processing 169 Inbound Packet Processing 170
AH and ESP and the "Cases" 171 IP Addressing in the Headers 173 Construction of the ESP Packet 175 Header Construction for Tunnel Mode 177 HMAC Applied to AH and ESP 179
MD5-HMAC-96 Within ESP and AH 180 MHAC-SHA-1 -96 Within ESP and AH 180
IPSecandNAT 181 Summary 182
CHAPTER 10 The Internet Key Distribution, Certification, and Management 183
What is Public Key Infrastructure (PKI)? 183 Certificates and Certification Authorities (CAs) 184 Support for Non-repudiation 185 Key Backup and Recovery 185 Using Two Key Pairs 186 Key Update and Management of Key Histories 186 Certificate Repositories and Certificate Distribution 187 Cross-certification 187
ISAKMP, ISAKMP DOI, and IKE 187 ISAKMP 188 The "Protection Suite" 188
Other Thoughts on Key Exchange 189 ISAKMP Negotiation Phases 190
Messages 191 The Generic Header 193 Data Attributes 194 The Payloads 194 OAKLEY and ISAKMP 205
Examples of ISAKMP Negotiations 205 The Base Exchange 206 The Identity Protection Exchange 207
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XIV CONTENTS
Authentication Only Exchange 208 The Aggressive Exchange 208
ISAKMP Domain of Interpretation (DOI) 209 IPSec/ISAKMP Payloads 210 Summary 214
CHAPTER 11 Internet Key Exchange (IKE) 215
IKE Basics 215 Definitions 216 Perfect Forward Secrecy 218 Aspects of IKE and ISAKMP 218 Modes to Establish Authenticated Key Exchange 218
Main Mode 219 Aggressive Mode 219 Quick Mode and New Group Mode 219 Four Methods Used with Main or Aggressive
Mode 219 Examples of IKE Message Exchanges 220
Phase One: Authenticated with Signatures 221 Phase One: Authenticated with
Public Key Encryption 222 Phase One: Authenticated with a
Revised Mode of Public Key Encryption 223 Phase One: Authenticated With a Pre-Shared Key 225 Phase Two: Quick Mode 225 New Group Mode 225 ISAKMP Informational Exchanges 226
Oakley Groups 226 Messages for a Complete IKE Exchange 226
Phase Two Using Quick Mode 227 IPSec, NAT, and IKE 227 Examples of PKI Vendors 231 Summary 232
CHAPTER 12 Security Operations in a Mobile Network 233
The IS-41-C Specification 233 The IS-41-C Model 234 The Five Security/Privacy Operations 235
CONTENTS xv
Authentication Parameters 236 Authentication of Mobile Station
Registration Procedures 237 The Parameters 237 At the Air Interface 237 On the Network Side 239
Unique Challenge-Response Procedures 240 The Parameters 240 At the Air Interface 240 On the Network Side 242
Authentication of Mobile Station Originating a Call 243 The Parameters 243 At the Air Interface 243 On the Network Side 243
Authentication of Call to a Terminating Mobile Station 245 The Parameters 245 At the Air Interface 247 On the Network Side 247
Updating the Shared Secret Data (SSD) 248 The Parameters 248 At the Air Interface and on the Network Side 249
Summary 250
CHAPTER 13 Follow-ups to This Book 251
APPENDIX A Coding for Prominant Security Functions 255
APPENDIX B Network Address Translation (NAT) 275
ABBREVIATIONS 279
INDEX 281