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<UL>

	<LI><A HREF="#Heading1">- 43 -</A>

	<UL>

		<LI><A HREF="#Heading2">Networking</A>

		<UL>

			<LI><A HREF="#Heading3">What Is TCP/IP?</A>

			<LI><A HREF="#Heading4">Hardware Requirements</A>

			<LI><A HREF="#Heading5">Configuring Linux Files</A>

			<UL>

				<LI><A HREF="#Heading6">What You Need Before You Start</A>

				<LI><A HREF="#Heading7">Setting Up the Dummy Interface</A>

				<LI><A HREF="#Heading8">Configuration Files</A>

			</UL>

			<LI><A HREF="#Heading9">Testing and Troubleshooting</A>

			<UL>

				<LI><A HREF="#Heading10">The netstat Command</A>

				<LI><A HREF="#Heading11">ping</A>

			</UL>

			<LI><A HREF="#Heading12">SLIP Connections</A>

			<UL>

				<LI><A HREF="#Heading13">Static IP Addresses</A>

				<LI><A HREF="#Heading14">Dynamic IP Addresses</A>

				<LI><A HREF="#Heading15">dip</A>

			</UL>

			<LI><A HREF="#Heading16">Setting Up PPP</A>

			<UL>

				<LI><A HREF="#Heading17">Setting Up a PPP Account</A>

				<LI><A HREF="#Heading18">Dialing Out: chat</A>

				<LI><A HREF="#Heading19">Running pppd</A>

				<LI><A HREF="#Heading20">Checking Problems</A>

				<LI><A HREF="#Heading21">PPP Authentication</A>

			</UL>

			<LI><A HREF="#Heading22">Summary</A>

		</UL>

	</UL>

</UL>



<P>

<HR SIZE="4">



<H2 ALIGN="CENTER"><A NAME="Heading1<FONT COLOR="#000077">- 43 -</FONT></H2>

<H2 ALIGN="CENTER"><A NAME="Heading2<FONT COLOR="#000077">Networking</FONT></H2>

<P><I>by Tim Parker</I></P>

<P>IN THIS CHAPTER</P>



<UL>

	<LI>What Is TCP/IP? 

	<P>

	<LI>Hardware Requirements 

	<P>

	<LI>Configuring Linux Files 

	<P>

	<LI>Testing and Troubleshooting 

	<P>

	<LI>SLIP Connections 

	<P>

	<LI>Setting Up PPP 

</UL>



<P>In this chapter, you will look at the world of networking. In particular, you

will learn the following:



<UL>

	<LI>What is TCP/IP?

	<P>

	<LI>How do you set up Linux to use TCP/IP and Ethernet?

	<P>

	<LI>What changes to your configuration files are necessary?

	<P>

	<LI>How can you test and troubleshoot Ethernet connections?

	<P>

	<LI>What is necessary for a SLIP and PPP connection?

</UL>



<P>Linux offers a complete implementation of TCP/IP (Transmission Control Protocol/Internet

Protocol), the protocol used extensively on the Internet and that is commonly found

in local area networks involving UNIX machines. All you need to create a network,

or to add your existing machine to a TCP/IP network, is a network card and some modifications

to files already on your Linux system.</P>

<P>Whether you are setting up two machines in your room to talk to each other, or

adding your Linux machine to an existing network of 5,000 workstations, the process

is the same.

<H3 ALIGN="CENTER"><A NAME="Heading3<FONT COLOR="#000077">What Is TCP/IP?</FONT></H3>

<P>TCP/IP is an open networking protocol, which simply means that the technical description

of all aspects of the protocol have been published. They are available for anyone

to implement on their hardware and software. This open nature has helped make TCP/IP

very popular. Versions of TCP/IP are now available for practically every hardware

and software platform in existence, which has helped make TCP/IP the most widely

used networking protocol in the world. The advantage of TCP/IP for a network operating

system is simple: Interconnectivity is possible for any type of operating system

and hardware platform that you might want to add.</P>

<P>TCP/IP is not a single protocol, but a set of over a dozen protocols. Each protocol

within the TCP/IP family is dedicated to a different task. All the protocols that

make up TCP/IP use the primary components of TCP/IP to send packets of data.</P>

<P>Transmission Control Protocol and Internet Protocol are two of the primary protocols

in the TCP/IP family. The different protocols and services that make up the TCP/IP

family can be grouped according to their purposes. The groups and their protocols

are the following:</P>

<P>Transport: These protocols control the movement of data between two machines.

TCP (Transmission Control Protocol): A connection-based service, meaning that the

sending and receiving machines communicate with each other at all times.<BR>

<BR>

UDP (User Datagram Protocol): A connectionless service, meaning that the two machines

don't communicate with each other through a constant connection.<BR>

<BR>

Routing: These protocols handle the addressing of the data and determine the best

routing to the destination. They also handle the way large messages are broken up

and reassembled at the destination. IP (Internet Protocol): Handles the actual transmission

of data.</P>

<P>ICMP (Internet Control Message Protocol): Handles status messages for IP, such

as errors and network changes that can affect routing.</P>

<P>RIP (Routing Information Protocol): One of several protocols that determine the

best routing method.<BR>

<BR>

OSPF (Open Shortest Path First): An alternative protocol for determining routing.<BR>

<BR>

Network Addresses: These services handle the way machines are addressed, both by

a unique number and a more common symbolic name. ARP (Address Resolution Protocol):

Determines the unique numeric addresses of machines on the network.</P>



<P>DNS (Domain Name System): Determines numeric addresses from machine names.</P>

<P>RARP (Reverse Address Resolution Protocol): Determines addresses of machines on

the network, but in a manner opposite of ARP.<BR>

<BR>

BOOTP (Boot Protocol): This starts up a network machine by reading the boot information

from a server. BOOTP is commonly used for diskless workstations.<BR>

<BR>

User Services: These are applications users have access to. FTP (File Transfer Protocol):

This transfers files from one machine to another without excessive overhead. FTP

uses TCP as the transport.</P>

<P>TFTP (Trivial File Transfer Protocol): A simple file transfer method that uses

UDP as the transport.<BR>

<BR>

TELNET: Allows remote logins so that a user on one machine can connect to another

machine and behave as though they are sitting at the remote machine's keyboard.<BR>

<BR>

Gateway Protocols: These services help the network communicate routing and status

information, as well as handle data for local networks. EGP (Exterior Gateway Protocol):

Transfers routing information for external networks.</P>

<P>GGP (Gateway-to-Gateway Protocol): Transfers routing information between Internet

gateways.<BR>

<BR>

IGP (Interior Gateway Protocol): Transfers routing information for internal networks.<BR>

<BR>

Others: These are services that don't fall into the categories just mentioned but

that provide important services over a network. NFS (Network File System): Allows

directories on one machine to be mounted on another, then accessed by users as though

the directories were on the local machine.</P>

<P>NIS (Network Information Service): Maintains user accounts across networks, simplifying

logins and password maintenance.</P>

<P>RPC (Remote Procedure Call): Allows remote applications to communicate with each

other using function calls.</P>

<P>SMTP (Simple Mail Transfer Protocol): A protocol for transferring electronic mail

between machines.<BR>

<BR>

SNMP (Simple Network Management Protocol): Used to obtain status messages about TCP/IP

configurations and software. It requires a loopback to be in place for proper operation.<BR>

<BR>

If you want to connect your Linux machine to a network, you need a network card.

Linux uses Ethernet, a network system that was designed to provide TCP/IP support.

A term you'll see often is packet, which is the bundle of data and routing instructions

that is assembled by TCP/IP and Ethernet to be sent over the network cables. All

messages are broken into packets, then reassembled properly at the destination.</P>

<P>All the TCP/IP protocol definitions are maintained by a standards body that is

part of the Internet organization. Although changes to the protocols occasionally

occur when new features or better methods of performing older functions are developed,

the new versions are almost always backward-compatible.

<H3 ALIGN="CENTER"><A NAME="Heading4<FONT COLOR="#000077">Hardware Requirements</FONT></H3>

<P>Linux requires an Ethernet card that is compatible with one of the network cards

in the following list: 3Com 3C505</P>

<P>3Com 3C503/16</P>

<P>Novell NE1000</P>

<P>Novell NE2000</P>

<P>Western Digital WD8003</P>

<P>Western Digital WD8013</P>

<P>Hewlett-Packard HP27245</P>

<P>Hewlett-Packard HP27247<BR>

<BR>

Hewlett-Packard HP27250<BR>

<BR>

Most Ethernet cards available today are compatible with one of these cards, but you

should carefully check the documentation with the card to ensure that you don't buy

a network card that won't work properly.</P>

<P>If you plan to do your networking over the telephone (using a serial port and

a modem), you don't need a network card, but you will need a fast modem compatible