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发信人: Lg (北斗七星), 信区: Linux
标 题: Home Networking With Linux
发信站: BBS 荔园晨风站 (Wed Sep 23 19:21:45 1998), 站内信件
"Linux Gazette...making Linux just a little more fun!"
Home Networking With Linux
By Glen Journeay
1.Home Networking Arrives
Progress on the Home Front
Advantages of Networks
Problems With Networks
2.Picking a Network Solution
Networking Choices
Advantages of Unix
Linux, the Unix for the GNU generation
3.Linux Networking in Action
GNU General Public License - Cant Beat the Price
Support - More Than You Paid For
Supported Hardware, Supported Software
Networking Support
IP Masquerade (Yes, You Can Eat That Cake!)
What Linux Isn't
4.So, What's the Catch
5.Just Do It!
6.The Future
Home Networking Arrives
It seems it's inevitable that the norm of home PCs becomes not just having one,
but a few. Often, we
acquire more than one computer at home when we upgrade from our existing system,
or we get one for
the kids to use, or the spouse brings one home for work. Somehow, we end up
with a bunch.
Dealing with the problems that arise with two or more computers is our first
exposure to being a network
administrator. Let's face it, as soon as you have more than one, you're trying
to move or share information
between them. The kids want to download a game from the Internet from one PC
and install it on another.
You brought home a file from work, only to realize that you don't have
compatible software at home.
You're constantly moving files on disk over the sneaker net to the PC
downstairs with the good printer.
The best solution to these problems, a network, is generally staring us in the
face out a work, we just don't
consider this solution to be economical or practical for home use. But, like
the idea of having more than
one TV twenty years ago, the day when home networks and multiple computers in
the household will be
common place is rapidly approaching. Even now, those among us with more money
(lots more sometimes)
are exploring totally networked and interactive houses. In new houses RJ-45
jacks for 10BaseT , and the
100 MHz 100BaseT Ethernet will be become as common as the phone jacks they look
like.
There are drawbacks to having a network at home. First off, we don't have a
whole Information Systems
(IS) department at home to support us. Also, the networking hardware and
software can be expensive. So
the advantages of networking have to out weigh the disadvantages of setup and
maintenance costs.
Picking A Network Solution
Let's examine some of the networking solutions available that are appropriate
for home networks. It turns
out that as the PC industry has matured, the variety of networking options has
increased. These range from
simple plug-n-go printer sharing networks all the way to firewall protected,
server supported intranets.
Normally, the cost and administration complexity rise as the power and
functionality of the network rise,
and as always, the proper way to choose the network you need is to determine
the functions that you
require. Here's a matrix listing normal network functions and solutions among
the common operating home
operating systems and two non-common networking solutions - Linux and Microsoft
NT:
Linux Unix NT Win95 Mac OS/2
Printer services x x x x x x
File server/sharing x * * * * *
Mail server x * * * - -
Domain Name Server x x * * * *
Web Server x x * * * *
Firewall x * * * - -
Routing x x x - - -
Gateway x x x - - -
Internet x x x x x x
Ethernet x x x x x x
Token Ring x * * * * *
Arcnet x * * * * *
Framerelay x * * - - -
ISDN x * * * - -
PPP x x x x x x
SLIP x x x x x x
TCP/IP x x x x x x
X.25 x * * * * *
IPX (Novell Netware) x x x x * *
SMB (Windows network) x x x x * *
Appletalk x * * * x *
NFS x x * * * *
x Support in system as supplied
* Support available as extra
- Support not available
Several home operating systems have been left off of the features comparison
chart, most of those have
been superceeded by their manufacturers. If your favorite is missing, our
apology, but discuss this with the
OEM since even they are urging you to switch. Also, several flavors of Unix
have been covered under just
the Unix heading with one Unix variety, Linux, set aside.
Linux since it's inception in 1991, has been different than the other Unixes in
several important ways. Linux
is a Unix clone written from scratch by Linus Torvalds with assistance from a
loosely-knit team of
developers on the Internet. Linux is (and always will be), with very few
restrictions (see the GNU General
Public License), free and has evolved into a full fledged, high performance
Unix originally based on the
Intel 386, now available on more different computer architectures than any
other single operating system in
the world. It should be noted that Linux is not the only freely distributed
Unix variety, it just seems to be
the best supported one at this time. It has good support available from the
team of developers on the
Internet and very extensive documentation in the form of HOWTO instructions,
FAQs and Unix man
pages, also available freely over the Internet. Linux distributions, the
operating system and all required
other software to have a fully functional system, are available for less than
$30 on a CDROM and for free
when downloaded from FTP sites on the Internet. Linux network servers for home
use actually require no
more than an old 386 in order to provide excellent performance for file servers,
print servers, mail servers
and network gateways and routers. Linux is very robust. Many Linux boxes around
the world have not
crashed or been rebooted for over a year. I do not think any Windows or
Macintosh product can make
this claim.
Windows NT, the networking oriented operating system offered by Microsoft, has
been available since
1991 too. It has all of the above features available for a price. This system
can easily cost over $1000 to
get almost all of the features listed above. It has good support available and
as it begins to replace Unix as
a major operating system on the Internet it will mature into a powerful
operating system available on many
different computer architectures. It currently cannot perform all of the
networking functions that Unix or
Linux can offer, but it will soon. Undoubtedly, NT with the continued support
of Microsoft has a bright
future.
Unix, of course, is a well established networking power house. In fact, Unix is
the workhorse of the
Internet. All of the protocols and services that the Internet were originally
based on were developed on
Unix. Because of the maturity of Unix, it has already gone through the growing
pains that are now plaguing
NT, such as security and crash problems. Despite predictions for years that
Unix use will decline, Unix use
continues to increase. Until the advent of Linux, there was no inexpensive,
powerful Unix available for the
home. Unix operating systems generally cost over $2000 for an operating system
with the features listed
above. And even now the relative complexity of Unix to most other operating
systems discourages wide
use except at colleges and large businesses.
Windows 95, the Macintosh OS and OS/2 also provide limited networking out of
the box, and with
additional software can perform as printer servers, file servers, mail servers,
name servers, firewalls, and
web servers. None of these operating systems were designed originally to
support intensive networking
services, but can do a good job for small networks with the right software and
hardware. These operating
systems can be outfitted to perform almost all of the above features for about
$500, and the basic
operating system is generally supplied with the PC. Also these systems are very
easy to setup and
configure.
Picking a home networking solution at the present time is largely dependent
upon your networking
requirements and budget. Obviously, most of us cannot afford to spend large
amounts of money unless a
home business is involved. Luckily at this time one of most powerful is also
the cheapest. Linux offers all of
the power of Unix and as software installation programs become more
sophisticated, it's also becoming
easier (almost painless) to install and administer. Indeed, if you have the
time, patience, disk space and an
Internet link, you can download Linux from several FTP sites located around the
world. With all this to
offer, you wonder why Linux is not being used more often, well, it is. Linux is
now being used on over 8
million computers around the world, in over 40% of the Internet Service
Providers (ISPs) in the world, by
large corporations, and US government agencies including NASA which recently
put an experiment on the
Space Shuttle run by a Linux computer.
Linux Networking in Action
Assuming that you do decide to set up a home network server using Linux, the
first step is to find PC
hardware that can be used to run the server. This should not present a problem
since Linux supports just
about any PC configuration made within the last five years, and as stated above,
an older 386 PC can
easily support a home network of five or more PCs. Linux runs on any
386/486/586/Pentium class
processor (including AMD, Cyrix), Dec Alpha, PowerPC (MkLinux for Apple),
M68xxx (Amiga, Atari),
Sun SPARC and MIPS. A minimum system based on a 386 requires 4 Meg of RAM (more
is better) and
50 Meg of disk space (200 Meg is better). While Linux can be run on a
386/4MB/20MB system, this
system will be very slow. Eight MB of memory and 50 MB of disk space is a more
realistic minimum for a
useful system. If this describes the PC you've been using as a door stop for
the last few years, then dust it
off, because it'll work fine. Many for the more popular Linux distributions
along with manuals are now
available at bookstores.
Don't worry if you have both Macintoshs and IBM PCs to support at home. Linux
happily coexists with all
of the most popular home operating systems. Linux knows the networking
protocols and file systems
native to a multitude of different operating systems on a network: MS DOS,
Windows for Workgroups,
Win95, Win NT, Mac OS, OS/2, Novell, Amiga, VAX and Unix. Details to implement
support for these
network support is provided by step-by-step instructions written in HOWTO
documents available on the
Internet.
You will need to decide on the hardware link to use at home. Ethernet is
probably the least expensive and
even slow Ethernet (10Mbps) provides performance that exceeds most home
requirements. Fast Ethernet
(100Mbps) is rapidly becoming the business Ethernet standard and is still
reasonable affordable for home
use. Ethernet interface cards range in price from $20 for an 8-bit ISA bus
10MHz card to $100 for a
100MHz card. 10Base2 seems to be the home user Ethernet cable choice, but
10BaseT isn't far behind.
With 10Base2 there is simply a coaxial cable "daisy chained" between computers
on the network. The
cable must not ever be discontinuous and 50 ohm terminators are required at
both ends of the daisy chain.
If you're having a home built, getting a 10BaseT cable network installed is
easily done and by choosing
Category 5 cable you can ensure an easy upgrade path to Fast Ethernet. Also the
50 ohm terminators are
not required. A 10BaseT system of more than two interface cards will require an
Ethernet hub, and be
warned that Category 5 cable is not cheap ($0.40/foot), so you'll pay more for
a 10BaseT installation, but
this a system will last longer, and is more convenient than 10base2. Linux
supports almost any network
interface card, so your networking requirements will probably depend more on
the PCs at the other end of
the Ethernet cable.
The Linux server could be the gateway to the Internet for all of the rest of
the PCs (or whatever) on your
home network. This will require a connection to a local or national ISP which
can provide an IP address
(preferably a static IP address) for the Linux gateway. The Internet link can
be over a modem, ISDN,
frame relay or ATM connection. Linux will also provide firewall services so
that no one will be able to
invade your home network from the Internet connection. Using a process called
IP masquerading, Linux
will provide Internet access to all of the PCs on your home network even with
only one valid IP address
and fully qualified domain name. This is done by making it appear that all of
the TCP/IP traffic coming from
your home network is coming from the Linux PC. When traffic comes back for the
other machines, the
Linux PC will act like the post office and sort all the network traffic back to
the proper PC. A Linux
machine can easily support two to five PCs surfing the Internet on a 28.8 modem
link. A Linux computer
can provide mail server services allowing you to create as many e-mail
addresses as you require at home.
All of the following can be done with ONLY ONE NORMAL PPP or SLIP link to an
Internet Service
Provider. There would be no extra charges for additional e-mail services or
subnetworks since all of these
functions would be performed at home by your Linux server. Are you tired of
having only one PC on the
Internet at home or paying for multiple Internet accounts? Then Linux is the
answer.
The Linux PC will provide printer and file server functions. Samba, a free
software package, supports the
SMB protocol used by Win95 and WFW. Samba is used by many large companies on
large company
networks. Once configured, it interfaces into the Windows operating system and
works flawlessly allowing
all of the network users to have individual and shared disk space, plus
allowing the user specify and use
any printer on the Linux server (or network printer for that matter). Here
again, as for all of Linux, the
software is available for free over the Internet, complete with installation
instructions and source code, and
the software is being actively developed and maintained by the original
developer. Linux has a similar
software package called Netatalk which provides similar support for the Apple
Localtalk protocol. A tape
backup system can be installed in the Linux server to automatically back up
your server.
Linux provides all of the network services traditionally associated with Unix.
Mail server service can be
accomplished using using sendmail or smail. Any user on the Linux system can
then have an e-mail
address. The e-mail account can be accessed from the network PCs using an
e-mail client with the POP3
protocol, such as Eudora or Pegasus. If your network needs Domain Name Service,
the named program
can provide it. If you support more than on type of network or several small
networks, the Linux server
can act as a gateway to tie all of the subnets together. Kernel routing rules
can also be used to allow the
server to act as a firewall and control access to the internal network. NFS,
which stands for Network File
System, allows computers to mount disk drives on remote machines. NFS is also
available with any Linux
distribution, although most other operating systems will require additional
software to use NFS. The other
network standard applications used on TCP/IP networks are always available: FTP,
telnet, remote shells,
ping, etc.
A Linux server also provides a state-of-the-art web server and Java development
system. Several web
servers are available for running on Linux with the Apache web server being the
most popular. Apache is
now the most popular web server on the Internet with over 45% of all web
servers running it. The Java
Development Kit is being ported from Sun Microsystems and provides a Java
compiler for developing
Java applications. In fact support for Java can be complied into the Linux
operating system allowing the
server to run native Java code. This feature is still being discussed for most
operating systems.
So, What's the Catch?
By now most of you are wondering what the catch is with running Linux. There's
no real catch. Linux has
been developing and maturing at a rate that far exceeds that of such well
supported systems as Windows
NT. For example, Windows NT just announced support for up to eight CPUs in a
multiprocessor system.
Linux now supports the Intel SMP multiprocessor specification which provides
support for up to twenty
CPUs in a single system.
With this power comes the complexity of the installation and support. In fact,
installation and maintenance
have been the subject of many recent articles. However, recent Linux
distributions have made the
installation process much easier and provide tools to make system
administration easier. Also helping the
situation is that, unlike Windows NT which is a relatively new operating system,
Unix has been around for
decades, so there exists a larger base of trained system personnel for Unix
systems than there are for
Windows NT. The traditional support market was with large installations at
large companies in a
workstation environment, but it's now shifting to support the use of Unix in
smaller businesses. Since
UNIX is such a strait forward operating system to develop software in, many
young and eager software
developers and hobbiests are turning to Linux for an inexpensive development
platform. These young
people are an excellent source of system administration knowledge, and most of
them can be contacted for
free advise on news groups on the Internet.
Linux, like other Unixes, has not previously been an operating system commonly
used at home. Many of
the applications developed for Unix systems are available on Linux. This was
traditionally the scientific
workstation area, and the quality of the applications reflects this.
Unfortunately, Linux suffers from a
shortage of applications oriented towards the average computer consumer. So,
even though a Linux makes
for an excellent server,and it is also an excellent workstation, running the
latest release of the free graphical
environment, X windows, it cannot run the latest version of Office 97 (although
many Windows
applications can be run using the WABI Windows emulator available from Caldera
software or the Wine
windows emulator). There are several software companies (and others) now
developing and selling
consumer applications to fill this gap.
Just Do It
Linux is an operating system with minimal initial cost, yet powerful enough to
easily handle a home network
or small business. Especially nice is that the older PC hardware which is
normally retired can be very
effectively used as a network server for a small network. Local Linux users
groups and computer stores
provide excellent Linux support. The support available from the Internet is
also excellent. It's always
comforting to receive an e-mail from the original developer of some Linux
software acknowledging that the
bug you've reported has been fixed.
The Future
In many ways, the advent and growth of Linux has gone hand-in-hand with the
growth of the Internet, and
the work of Linus Torvalds and many hard working developers. Presently, Linux
is an extremely capable
operating system available at an unbelievable price. Development of the
operating system to incorporate
the latest hardware and software developments is continuing at a rapid pace.
Although the future of the
Internet, the Personal Computer, and the Network Computer is unknowable, it
would seem that Linux will
be part of that future.
Copyright ? 1998, Glen Journeay
Published in Issue 28 of Linux Gazette, May 1998
--
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