This chapter explains how to set up a local-area network (LAN) that
includes a Linux Samba server, which lets Microsoft Windows and UNIX
systems access shared files and printers hosted by your Linux
system. The chapter explains how to administer a simple LAN and
describes how to install, configure, and administer Samba servers and
clients. Integrating your Linux system with an existing LAN is no more
complicated than setting up your own LAN; the chapter also explains
how to connect to an existing network. The chapter also explains how
to use Linux backup and recovery utilities so that client systems can
create and use backups stored on the server.
One of the great strengths of Linux is its powerful and robust
networking capabilities. The good news is that everything about
Linux's networking setup is open to inspection and completely
configurable. Nothing is hidden from the user, and no parameters are
forced on you. The challenge is to get the most out of this setup for
your needs.
Basic networking principles don't differ much
between Windows and Linux, and indeed the principles aren't
unfamiliar. This chapter starts with an overview of networking, and
then looks in more detail at Linux networking on a Local Area Network
(LAN). In the next two chapters, you'll learn about making a dialup
Internet connection, and setting up Wide Area Network (WAN)
services.
Most computers today handle network traffic much as the post office
handles mail. Think, for example, of the steps involved in sending and
receiving a letter. Your postal carrier must know where to drop off
and where to pick up mail. So your home must have some kind of
recognizable
interface; we call this a
mailbox. And whereas your postal carrier may know your neighborhood
quite well, delivery in other areas will require other carriers. Mail
is passed to these other carriers through a
gateway; we call this the Post
Office. Although you can think of the whole postal system as one big
network, it's easier to understand if you think of it as a hierarchy
of
subnetworks (or
subnets):
the postal system is divided into states, states are divided by zip
code, zip codes contain a number of streets, and each street contains
unique addresses.
Computer networking mirrors this model. Let's trace an email
message from you to a coworker. You compose the message and press
Send. Your computer passes the message to a network interface. This
interface may be a modem by which you dial up an ISP, or it may be an
Ethernet card that connects you to a LAN. Either way, on the other
side of the interface is a gateway machine. The gateway knows how to
look at the address of the recipient on the email message, and
interpret that message in terms of networks and subnets. Using this
information, your gateway passes the message to other gateways until
the message reaches the gateway for the destination machine. That
gateway in turn delivers the message via a recognizable interface
(such as modem or Ethernet card) to the recipient's inbox.
If you review this story, you can easily see what parts of networking
you'll need to configure on your Linux system. You'll need to know the
address of your machine. Just as the town name
Menlo
Park and the zip code
94025 are two
different names for the same location, you may have both a name,
called a
hostname, and a number, called an
IP number, that serve as the address for your
machine.
To translate between these two notations, you may need to know the
address of a
Domain Name Server. This is a
machine that matches IP numbers with hostnames. You'll also need to
know the address of a gateway machine through which network traffic
will be routed. Finally, you'll need to be able to bring up an
interface on your system for networking, and you'll need to assign a
route from that interface to the gateway.
While all of
this can seem complex, it really isn't any more complex than the
postal system, and functions in much the same way. Fortunately, Linux
comes with tools to help you automate network configuration. In this
chapter you'll look at networking on a LAN, and we'll start by looking
at how to set up LAN networking.
