computer networks in computer Science, Cheat Sheet of Computer Communication Systems

Download computer networks in computer Science and more Cheat Sheet Computer Communication Systems in PDF only on Docsity! THE TCP/IP GUIDE A Comprehensive, Illustrated Internet ProtocolA Reference by Charles M. Kozierok NO STARCH PRESS San Francisco B R I E F C O N T E N T S Contents in Detail xiii List of Figures xlv List of Tables Iv Acknowledgments Ixv About the Author Ixvii Introduction Ixix SECTION I: TCP/IP OVERVIEW AND BACKGROUND INFORMATION PART I-1: NETWORKING FUNDAMENTALS Chapter 1: Networking Introduction, Characteristics, and Types 5 Chapter 2: Network Performance Issues and Concepts 31 Chapter 3: Network Standards and Standards Organizations 45 Chapter 4: A Review of Data Representation and the Mathematics of Computing 61 PART 1-2: THE OPEN SYSTEMS INTERCONNECTION (OSI) REFERENCE MODEL Chapter 5: General OSI Reference Model Issues and Concepts 81 Chapter 6: OSI Reference Model Layers 101 Chapter 7: OSI Reference Model Summary 113 PART 1-3: TCP/IP PROTOCOL SUITE AND ARCHITECTURE Chapter 8: TCP/IP Protocol Suite and Architecture 121 SECTION III: TCP/IP APPLICATION LAYER PROTOCOLS PART III-1 r NAME SYSTEMS AND TCP/IP NAME REGISTRATION AND NAME RESOLUTION Chapter 50: Name System Issues, Concepts, and Techniques 825 Chapter 5 1 : TCP/IP Name Systems Overview and the Host Table Name System 841 Chapter 52: Domain Name System (DNS) Overview, Functions, and Characteristics 847 Chapter 53: DNS Name Space, Architecture, and Terminology..... 857 Chapter 54: DNS Name Registration, Public Administration, Zones, and Authorities 867 Chapter 55: DNS Name Server Concepts and Operation 887 Chapter 56: DNS Resolution Concepts and Resolver Operations 909 Chapter 57: DNS Messaging and Message, Resource Record, and Master File Formats 927 PART 111-2: NETWORK FILE AND RESOURCE SHARING PROTOCOLS Chapter 58: Network File and Resource Sharing and the TCP/IP Network File System (NFS) 953 PART 111-3: HOST CONFIGURATION AND TCP/IP HOST CONFIGURATION PROTOCOLS Chapter 59: Host Configuration Concepts, Issues, and Motivation 973 Chapter 60: TCP/IP Bootstrap Protocol (BOOTP) 977 Chapter 61 : DHCP Overview and Address Allocation Concepts 997 Chapter 62: DHCP Configuration and Operation 1013 Chapter 63: DHCP Messaging, Message Types, and Formats 1035 Chapter 64: DHCP Client/Server Implementation, Features, and IPv6 Support 1053 PART 111-4: TCP/IP NETWORK MANAGEMENT FRAMEWORK AND PROTOCOLS Chapter 65: TCP/IP Internet Standard Management Framework Overview 1069 Chapter 66: TCP/IP Structure of Management Information (SMI) and Management Information Bases (MIBs) 1083 Chapter 67: TCP/IP Simple Network Management Protocol (SNMP) Concepts and Operation 1099 Chapter 68: SNMP Protocol Messaging and Message Formats 11 13 X Brief Contents Chapter 69: TCP/IP Remote Network Monitoring (RMON) 1133 PART 111-5: TCP/IP APPUCATION LAYER ADDRESSING AND APPLICATION CATEGORIES Chapter 70: TCP/IP Application Layer Addressing: Uniform Resource Identifiers, Locators, and Names (URIs, URLs, and URNs) 1139 Chapter 71 : File and Message Transfer Overview and Application Categories 1163 PART 111-6: TCP/IP GENERAL FILE TRANSFER PROTOCOLS Chapter 72: File Transfer Protocol (FTP) 1169 Chapter 73: Trivial File Transfer Protocol (TFTP) 1 199 PART 111-7: TCP/IP ELECTRONIC MAIL SYSTEM: CONCEPTS AND PROTOCOLS Chapter 74: TCP/IP Electronic Mail System Overview and Concepts 121 7 Chapter 75: TCP/IP Electronic Mail Addresses and Addressing 1225 Chapter 76: TCP/IP Electronic Mail Message Formats and Message Processing: RFC 822 and MIME 1233 Chapter 77: TCP/IP Electronic Mail Delivery Protocol: The Simple Mail Transfer Protocol (SMTP) 1263 Chapter 78: TCP/IP Electronic Mail Access and Retrieval Protocols and Methods 1285 PART 111-8: TCP/IP WORLD WIDE WEB AND THE HYPERTEXT TRANSFER PROTOCOL (HTTP) Chapter 79: World Wide Web and Hypertext Overview and Concepts 1317 Chapter 80: HTTP General Operation and Connections 1329 Chapter 81: HTTP Messages, Methods, and Status Codes 1341 Chapter 82: HTTP Message Headers 1357 Chapter 83: HTTP Entities, Transfers, Coding Methods, and Content Management 1369 Chapter 84: HTTP Features, Capabilities, and Issues 1381 PART 111-9= OTHER FILE AND MESSAGE TRANSFER APPLICATIONS Chapter 85: Usenet (Network News) and the TCP/IP Network News Transfer Protocol (NNTP) 1397 Chapter 86: Gopher Protocol (Gopher) 1431 Brief Contents PART 111-10: INTERACTIVE AND ADMINISTRATIVE UTILITIES AND PROTOCOLS Chapter 87: TCP/IP Interactive and Remote Application Protocols 1437 Chapter 88: TCP/IP Administration and Troubleshooting Utilities and Protocols 1461 INDEX 1491 RFCs BY NUMBER 1537 XII Rri=( r . PART 1-2 THE OPEN SYSTEMS INTERCONNECTION (OSI) REFERENCE MODEL 79 5 General OSI Reference Model Issues and Concepts 81 History of the OSI Reference Model 82 General Reference Model Issues 83 The Benefits of Networking Models 83 Why Understanding the OSI Reference Model Is Important to You 84 How to Use the OSI Reference Model 85 Other Network Architectures and Protocol Stacks 86 Key OSI Reference Model Concepts 87 OSI Reference Model Networking Layers, Sublayers, and Layer Groupings 87 "N" Notation and Other OSI Model Layer Terminology 89 Interfaces: Vertical (Adjacent Layer) Communication 91 Protocols: Horizontal (Corresponding Layer) Communication 93 Data Encapsulation, Protocol Data Units (PDUs), and Service Data Units (SDUs) 95 Indirect Device Connection and Message Routing 98 6 OSI Reference Model Layers 101 Physical Layer (Layer 1) 102 Data Link Layer (Layer 2) 103 Network Layer (Layer 3) 105 Transport Layer (Layer 4) : 106 Session Layer (Layer 5) 109 Presentation Layer (Layer 6) 1 10 Application Layer (Layer 7) I l l 7 OSI Reference Model Summary 113 Understanding the OSI Model: An Analogy 113 Remembering the OSI Model Layers: Some Mnemonics 1 16 Summarizing the OSI Model Layers: A Summary Chart 1 17 PART 1-3 TCP/IP PROTOCOL SUITE AND ARCHITECTURE 119 8 TCP/IP Protocol Suite and Architecture 121 TCP/IP Overview and History 122 TCP/IP History and Development 122 Important Factors in the Success of TCP/IP 1 23 TCP/IP Services 125 The TCP/IP Client/Server Structural Model 125 Hardware and Software Roles '. 127 Transactional Roles 127 TCP/IP Architecture and the TCP/IP Model 128 Network Interface Layer 128 Internet Layer 1 29 Host-to-Host Transport Layer 1 30 Application Layer 130 TCP/IP Protocols 131 Contents in Detail XV SECTION II TCP/IP LOWER-LAYER CORE PROTOCOLS PART II-1 TCP/IP NETWORK INTERFACE LAYER PROTOCOLS 137 9 TCP/IP Serial Line Internet Protocol (SLIP) and Point-to-Point Protocol (PPP) Overview and Fundamentals 139 SLIP versus PPP 140 Serial Line Internet Protocol {SUP} 141 SLIP Data Framing Method and General Operation 141 Problems and Limitations of SLIP 142 Point-to-Point Protocol (PPP) Overview and Fundamentals 144 Development and Standardization 144 Function and Architecture 145 Advantages and Benefits 145 PPP Main Components 146 PPP Functional Groups 147 General Operation 147 PPP Link Setup and Phases 148 PPP Standards 151 10 PPP Core Protocols: Link Control, Network Control, and Authentication 155 Link Control Protocol (LCP) 155 LCP Packets 156 LCP Link Configuration 157 LCP Link Maintenance 159 LCP Link Termination 159 Other LCP Messages 1. 159 The Network Control Protocols (IPCP, IPXCP, NBFCP, and Others) 159 Operation of NCPs 160 The Internet Protocol Control Protocol (IPCP): An Example NCP 162 PPP Authentication Protocols: PAP and CHAP 162 PAP 162 CHAP 163 11 PPP Feature Protocols 167 PPP Link Quality Monitoring and Reporting (LQM, LQR) 168 LQR Setup 168 Using Link Quality Reports 169 PPP Compression Control Protocol (CCP) and Compression Algorithms 169 CCP Operation: Compression Setup 170 CCP Configuration Options and Compression Algorithms 171 Compression Algorithm Operation: Compressing and Decompressing Data 171 PPP Encryption Control Protocol (ECP) and Encryption Algorithms 172 ECP Operation: Encryption Setup 173 ECP Configuration Options and Encryption Algorithms 173 Encryption Algorithm Operation: Encrypting and Decrypting Data 174 PPP Multilink Protocol (MP, MLP, MLPPP) 175 PPP Multilink Protocol Architecture 176 PPP Multilink Protocol Setup and Configuration 177 PPP Multilink Protocol Operation 177 Contents in Detail PPP Bandwidth Allocation Protocol (BAP) and Bandwidth Allocation Control Protocol (BACP) 178 BACP Operation: Configuring the Use of BAP 179 BAP Operation: Adding and Removing Links 179 12 PPP Protocol Frame Formats 181 PPP General Frame Format , 182 Protocol Field Ranges 183 Protocol Field Values 184 PPP Field Compression 185 PPP General Control Protocol Frame Format and Option Format 1 86 PPP Control Messages and Code Values 187 PPP Control Message Option Format 1 88 Summary of PPP Control Message Formatting 190 PPP Link Control Protocol (LCP) Frame Formats 190 PAP and CHAP Frame Formats 192 PPP PAP Control Frame Formats 192 PPP CHAP Control Frame Formats 194 PPP Multilink Protocol (MP) Frame Format 195 PPP MP Frame Fragmentation Process 196 PPPMP Fragment Frame Format 196 PPPMP Fragmentation Demonstration 198 PART 11-2 TCP/IP NETWORK INTERFACE/INTERNET LAYER CONNECTION PROTOCOLS 201 13 Address Resolution and the TCP/IP Address Resolution Protocol (ARP) 203 Address Resolution Concepts and Issues 204 The Need for Address Resolution 204 Address Resolution Through Direct Mapping 206 Dynamic Address Resolution 209 TCP/IP Address Resolution Protocol (ARP) 212 ARP Address Specification and General Operation 213 ARP Message Format 216 ARP Caching 218 Proxy ARP <T221 TCP/IP Address Resolution for IP Multicast Addresses 223 TCP/IP Address Resolution for IP Version 6 224 14 Reverse Address Resolution and the TCP/IP Reverse Address Resolution Protocol (RARP) 227 The Reverse Address Resolution Protocol (RARP) 228 RARP General Operation 229 Limitations of RARP 231 PART 11-3 INTERNET PROTOCOL VERSION 4 (IP/IPV4) 233 15 Internet Protocol Versions, Concepts, and Overview 235 IP Overview and Key Operational Characteristics 236 IP Functions 238 Contents in Detail XVfl 22 IP Datagram Size, Fragmentation, and Reassembly 339 IP Datagram Size, MTU, and Fragmentation Overview 340 IP Datagram Size and the Underlying Network Frame Size 340 MTU and Datagram Fragmentation 341 Multiple-Stage Fragmentation 342 Internet Minimum MTU: 576 Bytes 343 MTU Path Discovery 343 IP Message Fragmentation Process 344 The IP Fragmentation Process 344 Fragmentation-Related IP Datagram Header Fields 346 IP Message Reassembly 347 23 IP Routing and Multicasting 351 IP Datagram Delivery 352 Direct Datagram Delivery 353 Indirect Datagram Delivery (Routing) 353 The Relationship Between Datagram Routing and Addressing 354 IP Routing Concepts and the Process of Next-Hop Routing 355 IP Routes and Routing Tables 357 IP Routing in a Subnet or Classless Addressing (CIDR) Environment 359 IP Multicasting 360 Multicast Addressing 361 Multicast Group Management 361 Multicast Datagram Processing and Routing 361 PART 11-4 INTERNET PROTOCOL VERSION 6 (IPV6) 363 24 IPv6 Overview, Changes, and Transition 365 IPv6 Motivation and Overview 366 IPv6 Standards 366 Design Goals of IPv6 367 Major Changes and Additions in IPv6 368 Transition from IPv4 to IPv6 370 IPv4 to IPv6 Transition: Differences of Opinion 370 IPv4 to IPv6 Transition Methods 371 25 IPv6 Addressing 373 IPv6 Addressing Overview: Addressing Model, Address Types, and Address Size 374 IPv6 Addressing Model Characteristics 374 IPv6 Supported Address Types 375 IPv6 Address Size and Address Space 376 IPv6 Address and Address Notation and Prefix Representation 378 IPv6 Address Hexadecimal Notation 378 Zero Compression in IPv6 Addresses 379 IPv6 Mixed Notation 380 IPv6 Address Prefix Length Representation 381 IPv6 Address Space Allocation 381 IPv6 Global Unicast Address Format 383 Rationale for a Structured Unicast Address Block 383 Generic Division of the Unicast Address Space 384 XX Contents in Detail IPv6 Implementation of the Unicast Address Space 384 Original Division of the Global Routing Prefix: Aggregators 385 A Sample Division of the Global Routing Prefix into Levels 386 IPv6 Interface Identifiers and Physical Address Mapping 388 IPv6 Special Addresses: Reserved, Private, Unspecified, and Loopback 389 Special Address Types 390 IPv6 Private Addresses Type Scopes 391 IPv6/IPv4 Address Embedding 392 IPv6 Multicast and Anycast Addressing 394 IPv6 Multicast Addresses 394 IPv6 Anycast Addresses 398 IPv6 Autoconfiguration and Renumbering .' 398 IPv6 Stateless Autoconfiguration 399 IPv6 Device Renumbering 400 26 IPv6 Datagram Encapsulation and Formatting 401 IPv6 Datagram Overview and General Structure 402 IPv6 Datagram Main Header Format 404 IPv6 Next Header Field 405 Key Changes to the Main Header Between IPv4 and IPv6 406 IPv6 Datagram Extension Headers 407 IPv6 Header Chaining Using the Next Header Field 407 Summary of IPv6 Extension Headers 409 IPv6 Routing Extension Header 410 IPv6 Fragment Extension Header 411 IPv6 Extension Header Order 411 IPv6 Datagram Options 412 27 IPv6 Datagram Size, Fragmentation, Reassembly, and Routing 415 Overview of IPv6 Datagram Sizing and Fragmentation 416 Implications of IPv6's Source-Only Fragmentation Rule 417 The IPv6 Fragmentation Process 418 IPv6 Datagram Delivery and Routing 420 PART 11-5 IP-RELATED FEATURE PROTOCOLS 423 28 IP Network Address Translation (NAT) Protocol 425 IP NAT Overview 426 Advantages of IP NAT .'. 428 Disadvantages of IP NAT 429 IP NAT Address Terminology 430 IP NAT Static and Dynamic Address Mappings 433 Static Mappings 433 Dynamic Mappings 433 Choosing Between Static and Dynamic Mapping 433 IP NAT Unidirectional (Traditional/Outbound) Operation 434 IP NAT Bidirectional (Two-Way/Inbound) Operation 437 IP NAT Port-Based (Overloaded) Operation 439 IP NAT Overlapping/Twice NAT Operation 442 IP NAT Compatibility Issues and Special Handling Requirements 445 Contents in Detail XXI 29 IP Security (IPsec) Protocols 449 IPsec Overview, History, and Standards 450 Overview of IPsec Services and Functions 451 IPsec Standards 451 IPsec General Operation, Components, and Protocols 452 IPsec Core Protocols 453 IPsec Support Components 453 IPsec Architectures and Implementation Methods 454 Integrated Architecture 455 Bump in the Stack (BITS) Architecture 455 Bump in the Wire (BITVV) Architecture 456 IPsec Modes: Transport and Tunnel : 457 Transport Mode 457 Tunnel Mode 457 Comparing Transport and Tunnel Modes 457 IPsec Security Constructs 460 Security Policies, Security Associations, and Associated Databases 460 Selectors 461 Security Association Triples and Security Parameter Index (SPI) 461 IPsec Authentication Header (AH) 461 AH Datagram Placement and Linking 462 AH Format 465 IPsec Encapsulating Security Payload (ESP) 466 ESP Fields 466 ESP Operations and Field Use 467 ESP Format 470 IPsec Internet Key Exchange (IKE) 471 IKE Overview 472 IKE Operation 472 30 Internet Protocol Mobility Support (Mobile IP) 475 Mobile IP Overview, History, and Motivation 476 The Problem with Mobile Nodes in TCP/IP 476 The Solution: Mobile IP 478 Limitations of Mobile IP 479 Mobile IP Concepts and General Operation 480 Mobile IP Device Roles 481 Mobile IP Functions 482 Mobile IP Addressing: Home and Care-Of Addresses 483 Foreign Agent Care-Of Address 484 Co-Located Care-Of Address 485 Advantages and Disadvantages of the Care-Of Address Types 485 Mobile IP Agent Discovery 486 Agent Discovery Process 486 Agent Advertisement and Agent Solicitation Messages 487 Mobile IP Home Agent Registration and Registration Messages 491 Mobile Node Registration Events 491 Registration Request and Registration Reply Messages 491 Registration Process 492 Registration Request Message Format 493 Registration Reply Message Format 495 Mobile IP Data Encapsulation and Tunneling 495 Mobile IP Conventional Tunneling 496 Mobile IP Reverse Tunneling 498 Mobile IP and TCP/IP Address Resolution Protocol (ARP) Operation 498 XXi! Contents in Detail IPv6 ND General Operational Overview 578 Host-Router Discovery Functions 579 Host-Host Communication Functions 579 Redirect Function 579 Relationships Between Functions 580 ICMFV6 Messages Used by ND 580 IPv6 ND Functions Compared to Equivalent IPv4 Functions 580 IPv6 ND Host-Router Discovery Functions 582 Host-Router Discovery Functions Performed by Routers 582 Host-Router Discovery Functions Performed by Hosts 583 IPv6 ND Host-Host Communication Functions 583 Next-Hop Determination 584 Address Resolution 584 Updating Neighbors Using Neighbor Advertisement Messages 585 Neighbor Unreachability Detection and the Neighbor Cache 585 Duplicate Address Detection 586 IPv6 ND Redirect Function 586 PART 11-7 TCP/IP ROUTING PROTOCOLS (GATEWAY PROTOCOLS) 589 37 Overview of Key Routing Protocol Concepts 591 Routing Protocol Architectures 591 Core Architecture , 592 Autonomous System (AS) Architecture 592 Modern Protocol Types: Interior and Exterior Routing Protocols 593 Routing Protocol Algorithms and Metrics 594 Distance-Vector (Bellman-Ford) Routing Protocol Algorithm 594 Link-State (Shortest-Path First) Routing Protocol Algorithm 595 Hybrid Routing Protocol Algorithms 595 Static and Dynamic Routing Protocols 595 38 Routing Information Protocol (RIP, RIP-2, and RIPng) 597 RIP Overview 598 RIP Standardization 598 RIP Operational Overview, Advantages, and Limitations 599 Development of RIP Version 2 (RIP-2) and RIPng for IPv6 600 RIP Route Determination Algorithm and Metric 600 RIP Routing Information and Route Distance Metric 600 RIP Route Determination Algorithm 601 RIP Route Determination and Information Propagation 601 Default Routes 604 RIP General Operation, Messaging, and Timers 604 RIP Messages and Basic Message Types 604 RIP Update Messaging and the 30-Second Timer 605 Preventing Stale Information: The Timeout Timer 605 Removing Stale Information: The Garbage-Collection Timer 606 Triggered Updates 606 RIP Problems and Some Resolutions 606 Issues with RIP's Algorithm 607 Issues with RIP's Metric 610 RIP Special Features for Resolving RIP Algorithm Problems 610 RIP Version-Specific Message Formats and Features 614 RIP Version 1 (RIP-1) Message Format and Features 614 RIP Version 2 (RIP-2) Message Format and Features 617 RIPng (RIPv6) Message Format and Features 620 Contents in Detail XXV 39 Open Shortest Path First (OSPF) 625 OSPF Overview 626 Development and Standardization of OSPF 626 Overview of OSPF Operation 627 OSPF Features and Drawbacks 627 OSPF Basic Topology and the Link-State Database (LSDB) 628 OSPF Basic Topology 628 LSDB Information Storage and Propagation 629 OSPF Hierarchical Topology .< 630 OSPF Areas 630 Router Roles in OSPF Hierarchical Topology 631 OSPF Route Determination Using SPF Trees 633 The SPF Tree 633 OSPF Route Determination 634 OSPF General Operation 637 OSPF Message Types 638 OSPF Messaging 638 OSPF Message Authentication 639 OSPF Message Formats 639 OSPF Common Header Format ..639 OSPF Hello Message Format 641 OSPF Database Description Message Format 641 OSPF Link State Request Message Format 643 OSPF Link State Update Message Format 643 OSPF Link State Acknowledgment Message Format 644 OSPF Link State Advertisements and the LSA Header Format 644 40 Border Gateway Protocol (BGP/BGP-4) 647 BGP Overview 648 BGP Versions and Defining Standards 649 Overview of BGP Functions and Features 650 BGP Topology 651 BGP Speakers, Router Roles, Neighbors, and Peers 652 BGP AS Types, Traffic Flows, and Routing Policies 653 BGP Route Storage and Advertisement 656 BGP Route Information Management Functions 656 BGP Routing Information Bases (RIBs) 656 BGP Path Attributes and Algorithm Overview 657 BGP Path Attribute Classes 658 BGP Path Attribute Characteristics 659 BGP Route Determination and the BGP Decision Process 659 BGP Decision Process Phases 660 Criteria for Assigning Preferences to Routes 660 Limitations on BGP's Ability to Select Efficient Routes 661 Originating New Routes and Withdrawing Unreachable Routes 661 BGP General Operation and Messaging 662 Speaker Designation and Connection Establishment 662 Route Information Exchange 662 Connectivity Maintenance 663 Error Reporting 663 BGP Detailed Messaging, Operation, and Message Formats 663 BGP Message Generation and Transport 663 BGP General Message Format 664 BGP Connection Establishment: Open Messages 666 BGP Route Information Exchange: Update Messages 667 BGP Connectivity Maintenance: Keepalive Messages 672 BGP Error Reporting: Notification Messages 673 XXVi Contents in Detail 41 Other Routing Protocols 677 TCP/IP Gateway-to-Gateway Protocol (GGP) 678 The HELLO Protocol (HELLO) 679 Interior Gateway Routing Protocol (IGRP) 681 Enhanced Interior Gateway Routing Protocol (EIGRP) 682 TCP/IP Exterior Gateway Protocol (EGP) 684 PART 11-8 TCP/IP TRANSPORT LAYER PROTOCOLS 687 42 Overview and Comparison of TCP and UDP 689 Two Protocols for TCP/IP Transport Layer Requirements 690 Applications of TCP and UDP 691 TCP Applications 691 UDP Applications 692 Summary Comparison of UDP and TCP 692 43 TCP and UDP Addressing: Ports and Sockets 695 TCP/IP Processes, Multiplexing, and Client/Server Application Roles 696 Multiplexing and Demultiplexing 696 TCP/IP Client Processes and Server Processes 697 TCP/IP Ports: TCP/UDP Addressing 698 Multiplexing and Demultiplexing Using Ports 699 Source Port and Destination Port Numbers 699 Summary of Port Use for Datagram Transmission and Reception 701 TCP/IP Application Assignments and Server Port Number Ranges 701 Reserved Port Numbers 702 TCP/UDP Port Number Ranges 702 TCP/IP Client (Ephemeral) Ports and Client/Server Application Port Use 703 Ephemeral Port Number Assignment 704 Ephemeral Port Number Ranges 704 Port Number Use During a Client/Server Exchange 705 TCP/IP Sockets and Socket Pairs: Process and Connection Identification 706 Common TCP/IP Applications and Well-Known and Registered Port Numbers 707 44 TCP/IP User Datagram Protocol (UDP) 711 UDP Overview, History, and Standards 712 UDP Operation 713 What UDP Does 713 What UDP Does Not Do 713 UDP Message Format 714 UDP Common Applications and Server Port Assignments 716 Why Some TCP/IP Applications Use UDP 716 Common UDP Applications and Server Port Use 717 Applications That Use Both UDP and TCP 718 45 TCP Overview, Functions, and Characteristics 719 TCP Overview, History, and Standards 720 TCP History 720 Overview of TCP Operation 721 TCP Standards 721 Contents in Detail XXVH Name Spaces and Name Architectures 831 Name Space Functions 831 Flat Name Architecture (Flat Name Space) 832 Hierarchical Name Architecture (Structured Name Space) 832 Comparing Name Architectures 833 Name Registration Methods, Administration, and Authorities 834 Name Registration Functions 834 Hierarchical Name Registration 835 Name Registration Methods 835 Name Resolution Techniques and Elements 836 Name Resolution Methods 837 Client/Server Name Resolution Functional Elements 838 Efficiency, Reliability, and Other Name Resolution Considerations 838 Efficiency Considerations 839 Reliability Considerations 839 Other Considerations 840 51 TCP/IP Name Systems Overview and the Host Table Name System 841 A Brief History of TCP/IP Host Names and Name Systems 842 Developing the First Name System: ARPAnet Host Name Lists 842 Storing Host Names in a Host Table File 842 Outgrowing the Host Table Name System and Moving to DNS 843 The TCP/IP Host Table Name System 843 Host Table Name Resolution 844 Host Table Name Registration 844 Weaknesses of the Host Table Name System 845 Use of the Host Table Name System in Modern Networking 846 52 Domain Name System (DNS) Overview, Functions, and Characteristics 847 DNS Overview, History, and Standards 848 Early DNS Development and the Move to Hierarchical Domains 848 Standardization of DNS and Initial Defining Standards 849 DNS Evolution and Important Additional Standards 850 DNS Adaptation for Internet Protocol Version 6 850 DNS Design Goals, Objectives, and Assumptions 851 DNS Design Goals and Objectives 851 DNS Design Assumptions 852 DNS Components and General Functions 853 DNS Name Space 854 Name Registration (Including Administration and Authorities) 854 Name Resolution 854 53 DNS Name Space, Architecture, and Terminology 857 DNS Domains and the DNS Hierarchical Name Architecture 858 The Essential Concept in the DNS Name Space: Domains 858 The DNS Hierarchical Tree Structure of Names 858 DNS Structural Elements and Terminology 860 DNS Tree-Related Terminology 860 DNS Domain-Related Terminology 860 DNS Family-Related Terminology 861 DNS Labels, Names, and Syntax Rules 863 DNS Labels and Label Syntax Rules 863 Domain Name Construction 864 XXX Contents in Delail Absolute (Fully Qualified) and Relative (Partially Qualified) Domain Name Specifications 865 Fully Qualified Domain Names 865 Partially Qualified Domain Names 866 54 DNS Name Registration, Public Administration, Zones, and Authorities 867 DNS Hierarchical Authority Structure and the Distributed Name Database 868 The DNS Root Domain Central Authority 868 TLD Authorities 869 Lower-Level Authority Delegation 869 Authority Hierarchy's Relationship to the Name Hierarchy 869 The DNS Distributed Name Database 869 DNS Organizational (Generic) TLDs and Authorities 870 Original Generic TLDs 870 New Generic TLDs 871 DNS Geopolitical (Country Code) TLDs and Authorities 874 Country Code Designations 874 Country Code TLD Authorities 875 Leasing/Sale of Country Code Domains 875 Drawbacks of the Geopolitical TLDs 876 Public Registration for Second-Level and Lower Domains 876 Registration Authority 877 Registration Coordination 878 DNS Public Registration Disputes and Dispute Resolution 878 Public Registration Disputes 878 Methods of Registration Dispute Resolution 880 The Uniform Domain Name Dispute Resolution Policy 880 DNS Name Space Administrative Hierarchy Partitioning: DNS Zones of Authority 881 Methods of Dividing a Name Space into Zones of Authority 882 The Impact of Zones on Name Resolution: Authoritative Servers 882 DNS Private Name Registration 884 Using Publicly Accessible Private Names 884 Using Private Names for Internal Use 885 Using Private Names on Networks Not Connected to the Internet 885 55 DNS Name Server Concepts and Operation 887 DNS General Operation 888 DNS Name Server Architecture and the Distributed Name Database 888 DNS Server Support Functions 889 The Logical Nature of the DNS Name Server Hierarchy 890 DNS Name Server Data Storage 890 Binary and Text Representations of Resource Records 890 Use of RRsand Master Files 891 Common RR Types 892 RR Classes 893 DNS Name Server Types and Roles 893 Master (Primary)/Slave (Secondary) Servers 893 Name Server Roles 895 Caching-Only Name Servers 895 DNS Zone Management, Contacts, and Zone Transfers 895 Domain Contacts 896 Zone Transfers 896 DNS Root Name Servers 899 Root Name Server Redundancy 899 Current Root Name Servers 900 Contents in Detail XXXJ DNS Name Server Caching 901 Name Server Caching 902 Caching Data Persistence and the Time to Live Interval 902 Negative Caching 904 DNS Name Server Load Balancing 904 Using Multiple Address Records to Spread Out Requests to a Domain 904 Using Multiple DNS Servers to Spread Out DNS Requests 905 DNS Name Server Enhancements 905 Automating Zone Transfers: DNS Notify 906 Improving Zone Transfer Efficiency: Incremental Transfers 907 Dealing with Dynamic IP Addresses: DNS Update/Dynamic DNS 907 56 DNS Resolution Concepts and Resolver Operations 909 DNS Resolver Functions and General Operation 910 Name Resolution Services 910 Functions Performed by Name Resolvers 910 DNS Name Resolution Techniques: Iterative and Recursive Resolution 911 Iterative Resolution 912 Recursive Resolution 913 Contrasting Iterative and Recursive Resolution 913 DNS Name Resolution Efficiency Improvements: Caching and Local Resolution 915 The Motivation for Caching: Locality of Reference 915 Name Resolver Caching 916 Local Resolution 916 DNS Name Resolution Process 917 A Simple Example of DNS Name Resolution 917 Changes to Resolution to Handle Aliases (CNAME Records) 920 DNS Reverse Name Resolution Using the IN-ADDR.ARPA Domain 920 The Original Method: Inverse Querying 921 The IN-ADDR.ARPA Name Structure for Reverse Resolution 921 RR Setup for Reverse Resolution 922 DNS Electronic Mail Support and Mail Exchange (MX) Resource Records 924 Special Requirements for Email Name Resolution 924 The Mail Exchange (MX) Record and Its Use 925 57 DNS Messaging and Message, Resource Record, and Master File Formats 927 DNS Message Generation and Transport 928 DNS Client/Server Messaging Overview 928 DNS Message Transport Using UDP and TCP 929 DNS Message Processing and General Message Format 930 DNS Message Header Format 932 DNS Question Section Format 935 DNS Message Resource Record Field Formats 935 DNS Common RR Format 936 RData Field Formats for Common RRs 936 DNS Name Notation and Message Compression 940 Standard DNS Name Notation 940 DNS Electronic Mail Address Notation 941 DNS Message Compression 941 DNS Master File Format 943 DNS Common Master File Record Format 944 Use and Interpretation of Partially Qualified Domain Names (PQDNs) 944 Master File Directives 945 Syntax Rules for Master Files 945 Specific RR Syntax and Examples 946 Sample Master File 948 XXXK Contents in Detail Option Categories 1043 Option Overloading 1044 Summary of DHCP Options/BOOTP Vendor Information Fields 1045 RFC 1497 Vendor Extensions 1045 IP Layer Parameters per Host 1046 IP Layer Parameters per Interface 1047 Link Layer Parameters per Interface 1048 TCP Parameters 1048 Application and Service Parameters 1048 DHCP Extensions 1050 64 DHCP Client/Server Implementation, Features, and IPv6 Support 1053 DHCP Server and Client Implementation and Management Issues 1054 DHCP Server Implementations 1054 DHCP Client Implementations 1056 DHCP Message Relaying and BOOTP Relay Agents 1056 BOOTP Relay Agents for DHCP 1057 DHCP Relaying Process 1057 DHCP Autoconfiguration/Automatic Private IP Addressing (APIPA) 1058 APIPA Operation 1059 APIPA Limitations 1060 DHCP Server Conflict Detection 1061 DHCP and BOOTP Interoperability 1062 BOOTP Clients Connecting to a DHCP Server 1063 DHCP Clients Connecting to a BOOTP Server 1063 DHCP Security Issues 1063 DHCP Security Concerns 1064 DHCP Authentication 1064 DHCP for IP Version 6 (DHCPv6) 1065 Two Methods for Autoconfiguration in IPv6 1065 DHCPv6 Operation Overview 1065 DHCPv6 Message Exchanges 1066 PART 111-4 TCP/IP NETWORK MANAGEMENT FRAMEWORK AND PROTOCOLS 1067 65 TCP/IP Internet Standard Management Framework Overview 1069 Overview and History of the TCP/IP Internet Standard Management Framework and Simple Network Management Protocol (SNMP) 1070 Early Development of SNMP 1070 The Two Meanings of SNMP 1071 Design Goals of SNMP 1071 Further Development of SNMP and the Problem of SNMP Variations 1072 TCP/IP SNMP Operational Model, Components, and Terminology 1072 SNMP Device Types 1072 SNMP Entities 1073 SNMP Operational Model Summary 1073 TCP/IP Internet Standard Management Framework Architecture and Protocol Components 1075 SNMP Framework Components 1075 SNMP Framework Architecture 1076 TCP/IP Internet Standard Management Framework and SNMP Versions (SNMPvl, SNMPv2 Variants, and SNMPv3) 1076 SNMPvl 1077 SNMPsec 1077 Contents in Detail XXXV SNMPv2 1078 SNMPv2 Variants 1078 SNMPv3 1079 TCP/IP Internet Standard Management Framework and SNMP Standards 1079 66 TCP/IP Structure of Management Information (SMI) and Management Information Bases (MIBs) 1083 TCP/IP SMI and MIBs Overview 1084 SNMP's Information-Oriented Design 1084 MIB and MIB Objects 1085 Defining MIB Objects: SMI 1086 TCP/IP MIB Objects, Object Characteristics, and Object Types 1087 MIB Object Characteristics 1087 SMI Data Types 1089 TCP/IP MIB Object Descriptors and Identifiers and the Object Name Hierarchy 1090 Object Descriptors 1091 Object Identifiers 1091 Structure of the MIB Object Name Hierarchy 1092 Recursive Definition of MIB Object Identifiers 1094 TCP/IP MIB Modules and Object Groups 1094 The Organization of MIB Objects into Object Groups 1094 MIB Modules 1096 MIB Module Format 1097 67 TCP/IP Simple Network Management Protocol (SNMP) Concepts and Operation 1099 SNMP Protocol Overview 1100 Early Development of SNMPvl 1100 SNMPv2 and the Division of SNMP into Protocol Operations and Transport Mappings 1101 SNMP Communication Methods 1102 SNMP Protocol Operations 1102 SNMP PDU Classes 1103 Basic Request/Response Information Poll Using GetRequest and (Get)Response Messages .... 1104 Table Traversal Using GetNextRequest and GetBulkRequest Messages 1105 Object Modification Using SetRequest Messages 1107 Information Notification Using Trap and InformRequest Messages 1109 SNMP Protocol Security Issues and Methods 1110 Problems with SNMPvl Security 1111 SNMPv2/v3 Security Methods 1111 68 SNMP Protocol Messaging and Message Formats 1113 SNMP Protocol Message Generation 1114 SNMP Transport Mappings 1114 UDP Message Size Issues 11 15 Lost Transmission Issues 1115 SNMP General Message Format 1116 The Difference Between SNMP Messages and PDUs 1117 General PDU Format 1117 SNMP Version 1 (SNMPvl) Message Format 1119 SNMPvl General Message Format 11 19 SNMPvl PDU Formats 1120 SNMP Version 2 (SNMPv2) Message Formats 1122 SNMP Version 2 (SNMPv2p) Message Format 1123 Community-Based SNMP Version 2 (SNMPv2c) Message Format 1124 XXXVi Contents in Detail User-Based SNMP Version 2 (SNMPv2u) Message Format 1124 SNMPv2 PDU Formats 1126 SNMP Version 3 (SNMPv3) Message Format 1129 69 TCP/IP Remote Network Monitoring (RMON) 1133 RMON Standards 1134 RMON MIB Hierarchy and Object Groups 1134 RMON Alarms, Events, and Statistics 11 36 PART 111-5 TCP/IP APPLICATION LAYER ADDRESSING AND APPLICATION CATEGORIES 1137 70 TCP/IP Application Layer Addressing: Uniform Resource Identifiers, Locators, and Names (URIs, URLs, and URNs) 1139 URI Overview and Standards 1140 URI Categories: URLs and URNs 1141 URI Standards 1142 URL General Syntax 1142 Common Internet Scheme Syntax 1143 Omission of URL Syntax Elements 1144 URL Fragments 1145 Unsafe Characters and Special Encodings 1145 URL Schemes and Scheme-Specific Syntaxes 1146 World Wide Web/Hypertext Transfer Protocol Syntax (http) 1146 File Transfer Protocol Syntax (ftp) 1147 Electronic Mail Syntax (mailto) 1147 Gopher Protocol Syntax (gopher) 1148 Network News/Usenet Syntax (news) 1148 Network News Transfer Protocol Syntax (nttp) 1148 Telnet Syntax (telnet) 1149 Local File Syntax (file) 1149 Special Syntax Rules 1149 URL Relative Syntax and Base URLs 1150 Interpretation Rules for Relative URLs 1151 Practical Interpretation of Relative URLs 1152 URL Length and Complexity Issues 1154 URL Wrapping and Delimiting 1155 Explicit URL Delimiting and Redirectors URL Abbreviation URL Obscuration, Obfuscation, and General Trickery URNs The Problem with URLs . Overview of URNs 156 156 156 159 159 160 URN Namespaces and Syntax 1160 URN Resolution and Implementation Difficulties ?. 1161 71 File and Message Transfer Overview and Application Categories 1163 File Concepts 1164 Application Categories 1164 General File Transfer Applications 1164 Message Transfer Applications 1164 The Merging of File and Message Transfer Methods 1165 Contents in Detail XXXVfi MIME Content-Type Header and Discrete Media 1248 Content-Type Header Syntax 1248 Discrete Media Types and Subtypes 1249 MIME Composite Media Types: Multipart and Encapsulated Message Structures 1253 MIME Multipart Message Type 1253 Multipart Message Encoding 1254 MIME Encapsulated Message Type 1257 MIME Content-Transfer-Encoding Header and Encoding Methods 1257 7-Bit and 8-Bit Encoding 1258 Quofed-Printable Encoding 1258 Base64 Encoding 1258 MIME Extension for non-ASCII Mail Message Headers 1261 77 TCP/IP Electronic Mail Delivery Protocol: The Simple Mail Transfer Protocol (SMTP) 1263 SMTP Overview, History, and Standards 1264 SMTP Standards 1264 SMTP Communication and Message Transport Methods 1265 Terminology: Client/Server and Sender/Receiver 1267 SMTP Connection and Session Establishment and Termination 1267 Overview of Connection Establishment and Termination 1268 Connection Establishment and Greeting Exchange 1268 Connection Establishment Using SMTP Extensions 1269 Connection Termination 1270 SMTP Mail Transaction Process 1271 Overview of SMTP Mail Transaction 1271 SMTP Mail Transaction Details 1272 SMTP Special Features, Capabilities, and Extensions 1274 SMTP Special Features and Capabilities 1275 SMTP Extensions 1276 SMTP Security Issues 1277 SMTP Commands 1279 SMTP Replies and Reply Codes 1281 Reply Code Structure and Digit Interpretation 1281 SMTP Multiple-Line Text Replies 1284 Enhanced Status Code Replies 1284 78 TCP/IP Electronic Mail Access and Retrieval Protocols and Methods 1285 TCP/IP Email Mailbox Access Model, Method, and Protocol Overview 1286 Email Access and Retrieval Models 1287 TCP/IP Post Office Protocol (POP/POP3) 1288 POP Overview, History, Versions, and Standards 1288 POP3 General Operation 1290 POP3 Session States 1290 TCP/IP Internet Message Access Protocol (IMAP/IMAP4) 1297 IMAP Overview, History, Versions, and Standards 1298 IMAP General Operation 1300 IMAP Session States 1300 IMAP Commands, Results, and Responses 1302 IMAP Not Authenticated State: User Authentication Process and Commands 1306 IMAP Authenticated State: Mailbox Manipulation/Selection Process and Commands 1307 IMAP Selected State: Message Manipulation Process and Commands 1309 TCP/IP Direct Server Email Access 1311 TCP/IP World Wide Web Email Access 1313 Contents in Detail PART 111-8 TCP/IP WORLD WIDE WEB AND THE HYPERTEXT TRANSFER PROTOCOL (HTTP) 1315 79 World Wide Web and Hypertext Overview and Concepts 1317 World Wide Web and Hypertext Overview and History 1318 History of Hypertext 1318 The World Wide Web Today ..., 1319 World Wide Web System Concepts and Components 1320 Major Functional Components of the Web 1320 Web Servers and Web Browsers 1321 World Wide Web Media and the Hypertext Markup Language 1322 Overview of HTML 1322 HTML Elements and Tags 1323 Common HTML Elements 1324 Common Text Formatting Tags 1326 World Wide Web Addressing: HTTP Uniform Resource Locators 1326 HTTP URL Syntax 1327 Resource Paths and Directory Listings 1328 80 HTTP General Operation and Connections 1329 HTTP Versions and Standards .' 1330 HTTP/0.9 1330 HTTP/1.0 1330 HTTP/1.1 1331 Future HTTP Versions 1332 HTTP Operational Model and Client/Server Communication 1333 Basic HTTP Client/Server Communication 1333 Intermediaries and the HTTP Request/Response Chain 1334 The Impact of Caching on HTTP Communication 1335 HTTP Transitory and Persistent Connections and Pipelining 1336 Persistent Connections 1337 Pipelining 1337 HTTP Persistent Connection Establishment and Management 1338 81 HTTP Messages, Methods, and Status Codes 1341 HTTP Generic Message Format 1342 HTTP Request Message Format 1343 Request Line 1344 Headers 1346 HTTP Response Message Format 1346 Status Line 1347 Headers 1348 HTTP Methods 1349 Common Methods 1349 Other Methods 1350 Safe and Idempotent Methods 1351 HTTP Status Codes and Reason Phrases 1352 Status Code Format 1352 Reason Phrases 1353 The 100 (Continue) Preliminary Reply 1356 Contents in Detail Xll 82 HTTP Message Headers 1357 HTTP General Headers 1358 Cache-Control Headers 1358 Warning 1359 Other HTTP General Headers 1360 HTTP Request Headers 1361 HTTP Response Headers 1364 HTTP Entity Headers 1365 83 HTTP Entities, Transfers, Coding Methods, and Content Management 1369 HTTP Entities and Internet Media Types 1370 Media Types and Subtypes 1370 HTTP's Use of Media Types 1371 Differences in HTTP and MIME Constructs 1371 HTTP Content and Transfer Encodings 1372 HTTP's Two-Level Encoding Scheme 1373 Use of Content and Transfer Encodings 1373 HTTP Data Length Issues, Chunked Transfers, and Message Trailers 1374 Dynamic Data Length 1375 Chunked Transfers and Message Trailers 1375 HTTP Content Negotiation and Quality Values 1378 Content Negotiation Techniques 1378 Quality Values for Preference Weights 1380 84 HTTP Features, Capabilities, and Issues 1381 HTTP Caching Features and Issues 1382 Benefits of HTTP Caching 1382 Cache Locations 1383 Cache Control 1384 Important Caching Issues 1385 HTTP Proxy Servers and Proxying 1386 Benefits of Proxies 1386 Comparing Proxies and Caches 1387 Important Proxying Issues 1387 HTTP Security and Privacy 1388 HTTP Authentication Methods 1389 Security and Privacy Concerns and Issues 1389 Methods for Ensuring Privacy in HTTP 1390 HTTP State Management Using Cookies 1390 Issues with Cookies 1391 Managing Cookie Use 1393 PART 111-9 OTHER FILE AND MESSAGE TRANSFER APPLICATIONS 1395 85 Usenet (Network News) and the TCP/IP Network News Transfer Protocol (NNTP) 1397 Usenet Overview, History, and Operation 1398 History of Usenet 1398 Usenet Operation and Characteristics 1399 Usenet Transport Methods 1400 Usenet Communication Model 1401 Usenet's Public Distribution Orientation 1402 Usenet Communication Process 1402 xlH Contents in Detail