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Connecting to the Internet: A Practical Guide about LAN-Internet Connectivity

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Connecting to the Internet: A Practical Guide about LAN-Internet Connectivity


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  • Copyright 1999
  • Dimensions: 5-3/8x8-1/4
  • Pages: 320
  • Edition: 1st
  • Book
  • ISBN-10: 0-201-37956-2
  • ISBN-13: 978-0-201-37956-3

System and network administrators faced with the challenge of building and maintaining permanent LAN-to-Internet connections are often in need of additional information in order to complete this complex task. This practical handbook is a guide to the entire process of connecting a private network to the Internet and then maintaining that connection.

Comprehensive yet succinct, Connecting to the Internet provides essential information without the burden of extraneous detail. Using a step-by-step approach, this book covers the processes of planning, designing, implementing, and maintaining an effective and secure LAN-to-Internet connection--from TCP/IP essentials, to choosing the most appropriate Internet Service Provider, to setting up a firewall.

Specifically, you will find coverage of:

  • TCP/IP essentials and standard Internet service protocols, such as DNS, FTP, Mail, News, Telnet, the Web, and SSL
  • Criteria for choosing an Internet Service Provider, including connection capacity, installation services, Web hosting, security, VPNs, remote access, multicast, knowledge services, and pricing
  • Circuitry and equipment configuration for your WAN
  • Security technologies--packet filters, circuit proxies, application gateways, network address translation, firewalls, vendors, security policies, and auditing
  • Network design and equipment selection
  • Staging and testing the design, including how to run routing diagnostics and security testing
  • Implementing the new connection, going live with the ISP, and troubleshooting the WAN
  • Managing the LAN-Internet connection, with discussions on security breaches, usage monitoring, and performance issues

Each technical chapter contains checklists to help you track critical steps in the process. In addition, experienced-based tips throughout the book will keep you from falling into expensive and time-consuming pitfalls.




Connecting to the Internet gives the audience of network and system administrators the skills and know-how they need to connect their LANs (Local Area Networks) to the Internet, and then maintain that connection. This book is a quick step-by-step guide complete with checklists that the readers can use to test their systems when they are building and maintaining their connection to the Internet.

Here is a sample checklist from the book. This checklist is from chapter 7 - Implementing and Validating Your New Connection

    1. Checklist - Implementation & Validation


  • Order completion date obtained?
  • Activation date of Internet connection obtained?
  • WAN premises equipment assembled and operational prior to circuit completion?
  • WAN router disconnected from LAN during completion phase?
  • Test equipment and configurations removed from your network?
  • Have you obtained the circuit ID from the telecom or ISP?
  • Have you asked to be a contact on the circuit with the telecom?


  • Equipment with its final IP and routing configuration before activation
  • Temporarily deactivate security
  • Test WAN connectivity
  • Test routing to the Internet
  • Test DNS and Mail
  • Reactivate security


  • Check WAN router for status of circuit (UP or DOWN).
  • If working with a T1 or E1 span, check your premises equipment for proper configuration.
  • If working with a T1 or E1 span, be prepared for the telecom to conduct loopback tests.
  • If working with frame relay, check for correct DLCI values in your equipment configuration.
  • If working with frame relay, also check whether LMI is being used or not.
  • If working with ISDN, try using the equipment to dial another number besides the ISP.
  • If working with ISDN, make certain your equipment is configured properly to dial the ISP!=s ISDN telephone number.


  • Security test matrices created for testing?
  • Separate ISP account used for testing? Guest server from ISP available?
  • Troubleshooting services
  • DNS resolution works properly
  • Outbound routing is proper
  • Inbound routing is proper
  • Internet site is available
  • Security policy is blocking services
  • Security policy is misconfigured
  • Connection released for general use

Sample Content

Table of Contents

Preface—Look before You Leap.




1. TCP/IP Internetworking and Internet Services.

Comparing TCP/IP to the OSI Reference Model.

Packet-Based Communication.

Media Access Control (MAC).


Unicast, Broadcast, and Multicast Packets.

Communication in IP Networks.

Address Resolution Protocol (ARP).


Route Advertisement and Learning.

Internet Control Message Protocol (ICMP).

Internet Services.

Emphasis on TCP and UDP.

TCP Connections.

UDP Data Streams.

Request for Comments (RFC).

Standard Internet Service Protocols.

Domain Name System (DNS).

File Transfer Protocol (FTP).


News (NNTP).

Terminal Emulation (Telnet).

Web (HTTP).

Security/Encryption (SSL).

Non-TCP-Based and Non-UDP-Based Services.

IP Protocols.

IP in IP Encapsulation.

Generic Routing Encapsulation (GRE).

2. Selecting Your Internet Service Provider.

Chapter Overview.

Types of ISPs.

Network Service Providers.

Internet Service Providers (Resellers).

Which Type of ISP Is Right for You?

Basic Access Products.

Internet Services Provided.

Connection Capacity (Bandwidth).

Access Provisioning (WAN Circuits).

Equipment Selection and Provisioning.

Installation and Setup Services.

Domain Name Registration.

Mail Exchange (MX) Records.

Allocation of an IP Address Pool.

Activation Support (Installation).

Post-Sales Support.

Extended Services.

Web Hosting.


Virtual Private Networks.

Remote Access.


Multicasting and MBone.

News Feed.

Knowledge Services (Consulting).

Capacity Scaling and Oversubscription.

Network Infrastructure.


Fixed versus Usage-Based Pricing.

Obtaining Quotations.

Contract Terms.


Checklist-Selecting the ISP.

3. Provisioning Your Wide Area Network.

Chapter Overview.

Circuit Capacity (Bandwidth).

DS-1 Circuits (E-1 and T-1).

Dual DS-1 Circuits.

DS-3 Circuits (T-3 and E-3).

Components of WAN Circuits.

Circuit Technologies.


Frame Relay.




Delivering the Circuit.


Premise Demarcation.

Circuit Conditioning.

North American T-1.

European E-1.

North American T-3.

Premise Equipment Configuration and Connections.


T-1 Circuits.

E-1 Circuits.

T-3 Circuits.

ISDN Network Termination.

Checklist-WAN Provisioning.

4. Planning Your Security.

Chapter Overview.

The Real Need for Security.

World View, Default Stance, and Direction.

World View.

Default Stance.

Default Action.


Access Control Technologies.

Packet Filtering.

Circuit Proxies.

Application Gateways.

Stateful Inspection.

Network Address Translation.

Firewall Products Explained.


Attack Screening.


Encryption and Virtual Private Networks.

Event Logging and Intrusion Notification.

Other Integrated Services.


Typical Policies.

Outbound Traffic.

Inbound Traffic.

Service-Specific Recommendations.

Problematical Services.

Security Auditing.


Software Tools.

Auditing Services.

Keeping Current.


5. Designing Your Network Architecture.

Chapter Overview.

Delineate Your Service Objectives.

Services Accessed from the Internet.

Services Provided to the Internet.

Other Services.

Assess Your Design Factors.



Select a Prototype Design.

Design 1-Single Filter for Screening Internal Hosts.

Design 2-Single Filter for Screening Servers.

Design 3-Single Filter with Screened Subnet.

Design 4-Dual Filter with Screened Subnet.

Determine Your IP Architecture.

IP Addressing.

IP Subnetting.

Configuring IP Routing (Tips and Traps).

Equipment Selection.


WAN Interfaces for Routers.

Reiterating the Design Process.

Checklist-Network Architecture and Equipment Selection.

6. Staging and Testing Your Design.

Chapter Overview.

Assemble Your Tools.

Software Utilities.

Network Analyzer.

Routing Diagnostics.

Server Applications.

Client Applications.

Network Hardware.

Staging Equipment.

Test Your Routing.

Test Your Security (Filtering).

Test Mandatory Services.

Checklist-Staging and Testing.

7. Implementing and Validating Your New Connection.

Chapter Overview.

Complete the WAN Circuit.

Going Live with the ISP.

Deactivate Your Security.

Test WAN Connectivity.

Test Routing to the Internet.

Test Connectivity to DNS and Mail Servers.

Reactivate Security.

Troubleshooting the WAN.

Validating Operation and Security after Start-Up.

Checklist-Implementation and Validation.

8. Managing Your Connection.

Chapter Overview.

Evaluating New Services.

Checking for Security Breaches.

Usage Monitoring and Baselining.

Addressing Performance and Connectivity Issues.

Moving to a New ISP.

Your Internet Connection on Autopilot.

Appendix A: Network Address Translation.

Appendix B: Virtual Private Networks.

Appendix C: How the Internet Functions.

Backbone Construction.

Domain Name System.

The Internet Management and Services.

Obtaining IP Addresses and Domain Names.

Internet Problems.

Predicted Growth and Capacity Planning.

IP Address Depletion.

Appendix D: Dynamic Host Configuration Protocol.

Appendix E: Helpful Web Sites.

Firewall/Security Sites.

Freeware Sites.

Internet Administration Sites.

Internet Service Providers.



Index. 0201379562T04062001


Look before You Leap

As Internet usage continues to grow throughout the world, increasing numbers of network administrators face the task of connecting their local area networks (LANs) to the Internet. For these personnel, this project represents an entirely new challenge, and in some cases a daunting one. After all, there is much to consider when implementing a dedicated connection to the Internet.

In the past, only a small group of people possessed the skills and knowledge needed to build an Internet connection. Until recently, the Internet was not a huge network. Furthermore, until the 1990s, access was too expensive for small and midsize organizations. Lower access prices and an increase in the number of ISPs, however, have now led to a pervasive expansion of the Internet.

Today, network professionals need basic information about how to connect their LANs to the Internet. This book seeks to fill this information gap and explain the process of building and maintaining a dedicated connection from the LAN to the Internet. Unlike other networking projects, building a dedicated Internet connection poses a unique challenge because it requires functional expertise in a range of technical subjects, including:

  • TCP/IP
  • Internet services and functions
  • Wide area networking
  • Security
  • Network architecture
  • Testing and validation procedures

Moreover, constructing an Internet connection usually requires the administrator to involve other external parties, such as the Internet service provider (ISP), the telecommunications vendor, and sometimes a consultant (or two). Thus the process of connecting the LAN to the Internet requires both technical and project management expertise.

Many excellent books focus on specific aspects of Internet connectivity. In particular, the most popular subjects are TCP/IP and security. Excellent books can also be found on wide area networks (WANs) and Internet-specific topics such as Domain Name System (DNS). Yet, few books bring together the pertinent parts of these technical subjects in a manner that enables the reader to start building a connection without overloading him or her with unnecessary information. This book focuses on what is immediate and necessary to build such a connection.

This book really describes the process of connecting your LAN to the Internet. Its structure reflects the order in which you carry out tasks necessary to build an Internet connection. Each chapter discusses one particular element of the construction process, providing both conceptual information and useful tips on how to avoid common pitfalls in the construction process.

With the exception of Chapter 1, which provides additional information about TCP/IP and Internet services that is pertinent to building a connection, each chapter includes a checklist of key points to address when you build your connection. This book is your travel guide to putting your LAN on the Internet.


This book is intended for network and system administrators who are implementing an Internet connection for the first time, as well as managers who are overseeing the construction of such a connection. We have attempted to make the book international in scope so that the contents will prove useful to administrators throughout the world.


Only one prerequisite exists for readers of this book--an understanding of the TCP/IP communications protocol. In particular, we assume the reader has a basic knowledge of the following:

  • OSI Reference Model
  • IP addressing
  • Subnet masking
  • Default gateways
  • Domain Name System (DNS)


I never really understood why authors write acknowledgements until I wrote a book myself. Now I understand. Most books, including this one, are really a joint effort. Although the author may write the words, he or she depends on the support of many folks. This support includes sharing ideas, offering opinions, and encouraging the author's effort.

Without the help of many people, this book would not have been possible. In particular, I owe a world of thanks to Saskia (my spouse) for putting up with my crazy project, especially during weekends when we should have been doing fun things like backpacking. I also wish to thank my family and friends, who helped me keep my sense of humor and direction throughout the writing process.

Many thanks go out to my colleague and friend, Darryl Black, whom I blame entirely for this book. (I am joking, of course!) Without his involvement, technical skills, and encouragement over an occasional beer, I would not have completed this project. I also wish to acknowledge my colleagues at 3Com, from whom I have learned much over the years. Many thanks go to my managers, Scott Graham and Adam Wasylyshyn.

Of course, nothing would have been possible without the guidance of my editor, Mary Hart, and the Addison Wesley Longman team. In addition, I am indebted to the technical reviewers of this text, who shared their experiences, thoughts, and comments on Internet connectivity and made many suggestions about how to improve the book. They include Dustin Andrews, Howard Lee Harkness, Richard P. Jussaume, Brendan Kehoe, Dana Love, Alain Mayer, James McGovern, Ravi Prakash, Thomas H. Ptacek, Ian Redfern, Dan Ritter, and Vincent Stemen.

--Andrew F. Ward



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