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Computer Rescue, Restoration, and Reuse Center, a program benefitting the Sciencenter of Ithaca
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The Home-Brew LAN
Gene's Machine
This project is out of date. There are
numerous small wired or wireless firewall/LAN/router/modem gadgets
available that do the same thing. They come with such a large
variety of combinations of functions that you can probably find
one that just fits your needs. Many can be purchased for under $100,
sometimes way under $100. Since many people are switching
to the wireless LANs we may begin to see used "wired"
LAN equipment at Babbage's.
If you have more than one computer a small network can be useful.
You can share files between computers or use a bigger computer
to store files for smaller computers. Most computers can be made
to share a single printer using a network. You could even experiment
with building your own web or chat server. The possibilities are
limited by your imagination. Add a means to connect your private
network to the Internet and you are really "wired".
The Project
Use outdated computing equipment to
build a Local Area Network (LAN) with up to 252 devices and
connect it to the Internet through a router that is also
a moderately good firewall.
The router automatically configures devices on the LAN using
DHCP (Dynamic Host Configuration Protocol). To the Internet it
looks like a single device even though there are a number of devices
using the Internet through it. Once it's setup the router may
be managed from one of the computers on your network using a telnet,
or secure shell and maybe a web browser.
Requirements
To do this project you will need
A working 486 computer with 12 Mbytes of RAM, a floppy drive./LI>
Two network cards or a telephone modem and one network card.
A floppy disk. The router is run from one bootable floppy.
A networked Windows or Linux desktop computer is useful to
get the needed software from the Internet and build the floppy disk.
You will also want a hub and wiring to connect your computers together.
Costs and benefits
Software cost: All of the software freely available on the web.
Hardware cost: Try Babbage's Basement. All of the hardware
is stuff that people throw away so your ingenuity in locating
castoffs goes a long way.
Benefit: Have your own little network.
Benefit: Projects are learning opportunities and fun to do.
Benefit: Change, experiment with and adapt the basic project
to meet your needs.
Downside: You can buy a small box that does the basics for
under $100 US and save time, effort, aggravation and electricity.
Overview
The "Old Computer" will have two network connections.
One to the Internet using a telephone modem, an ISDN line, a cable
modem or even a direct connection. The second network connection
is to the local network. A box called a hub (or concentrator)
is used to multiply this one connection into the many needed by
the local network.
The software needed to run the project is called Coyote Linux.
It is not the only possibility. There are at least half-a-dozen others.
Coyote Linux fits on a single bootable floppy disk. It provides
a DHCP server that automatically configures the devices connected
to the local network. It also handles connections to the Internet
on behalf of the local devices. First it connects as needed and
disconnects after a timeout period that you set. Second it does
some routing magic that moves data between the local network and
the Internet. The routing magic also acts as modest firewall.
It is not foolproof. The Coyote Linux FAQ discusses good ways
to make it better but these are not for novices.
The Coyote Linux package is under 7 Mbytes in size. Either
the Windows Wizard or the Linux shell script version can be downloaded
from the web and unpacked using a desktop computer. Both prompt
you for information needed to build a bootable floppy disk for
your system and then make the floppy. You must gather the information
to answer the questions. The success of the project depends on
how carefully you have done the homework. It is useful to run
the Coyote installer a couple of time just to get an idea what
the questions are.
Once you start Coyote Linux you can interact with it to monitor
what going on and to change settings. At first you will use the
monitor and keyboard connected to your project. When you start
Coyote up, you are presented with a menu of options. One of them
lets you configure Coyote as a telnet server. Using telnet, you
can connect to Coyote from your main computer (assuming Coyote
is running happily and your network is operating in good order).
If you were able to use Linux to set up your Coyote disk you will
be able to add ssh (Secure SHell) and "webctl" which
allows you to work with Coyote through your web browser. The reason
Linux allows this and Windows doesn't is that Linux is able to
put up to 1.7 Mbyte on a 3.5 inch floppy whereas Windows cannot.
The material that follows will cover acquiring the hardware
and learning about what it is you've got; because that's what
a place like Babbage's Basement knows about. Information about
Coyote Linux
is already available on the web. Other information sources
will be cited throughout.
A nice project
overview
can be found in this presentation by Ted Ruegsegger.
Getting the Hardware
Every year thousands of old computers enter the waste stream.
The problem of how to get rid of them is becoming a major headache.
Therefore, it would be a shame to pay very much for an 486 computer
with only a floppy drive and maybe a network card. You may have
one. You might find one at the curb, in a thrift store, at a flea
market, at a garage sale, or maybe at Babbage's Basement. Don't
be tempted to pay extra for one because the seller is emotionally
attached to it. Often your place of business or some other local
business will be getting rid of old computers.
The example on the left is one that I pulled from a pile of
unsorted computers at Babbage's Basement. The floppy drive
was hanging out and it was missing both the hard-drive and memory.
It was probably headed for the pile of $2 hulks on the display floor.
Since it was clean, small and had the floppy drive and a
network card it was perfect for attempting to set up a
local area net at Babbage's Basement using Coyote Linux.
I think this example may have been part of a point-of-sale
terminal rather than a consumer desktop.
It's useful to have good technical data for a given computer.
Make a note of any numbers on the computer; type, model, serial
number, etc. Browse around in the "technical support"
area of the manufacturer's web site or try typing the model number
into a search engine. Usually I am able to find quite a bit of
data. I didn't find any for the example computer but there was
useful information inside the computer's cover.
On checking out this box I found the main board had 4 Mbytes
of built in RAM and a dead battery. If you look in the desk drawer
of anyone who has done a memory upgrade you will find a couple
of 4 Mbyte RAMs. Not all of them work in every computer so you
need to find the right type. Fortunately there aren't that many
different types and the most common RAMs work in PCs. Two 4 Mbyte
RAMs brought this system up to 12 Mbytes; that's optimal for this
project. As for the battery, it's best to buy a fresh one.
The example on the left is one that I pulled from a pile of
unsorted computers at Babbage's Basement. The floppy drive was
hanging out and it was missing both the hard-drive and memory.
It was probably headed for the pile of $2 hulks on the display
floor. Since it was clean, small and had the floppy drive and
a network card it was perfect for attempting to set up a local
area net at Babbage's Basement using Coyote Linux. I think this
example may have been part of a point-of-sale terminal rather
than a consumer desktop.
It's useful to have good technical data for a given computer.
Make a note of any numbers on the computer; type, model, serial
number, etc. Browse around in the "technical support"
area of the manufacturer's web site or try typing the model number
into a search engine. Usually I am able to find quite a bit of
data. I didn't find any for the example computer but there was
useful information inside the computer's cover.
On checking out this box I found the main board had 4 Mbytes
of built in RAM and a dead battery. If you look in the desk drawer
of anyone who has done a memory upgrade you will find a couple
of 4 Mbyte RAMs. Not all of them work in every computer so you
need to find the right type. Fortunately there aren't that many
different types and the most common RAMs work in PCs. Two 4 Mbyte
RAMs brought this system up to 12 Mbytes; that's optimal for this
project. As for the battery, it's best to buy a fresh one.
Monitor, keyboard and mouse: The mouse isn't needed because
Coyote Linux is "command driven", like DOS. Maybe the
monitor and keyboard aren't needed either. Some systems will complain
unless these are attached to the computer when it starts. Our
example box, didn't complain. So how do you do anything with this
computer? Initially you borrow a monitor and keyboard from
another computer. When you have the project running happily, you
can set it up to use telnet, ssh or "webctl" and control
it from a computer on your network. If you must have a monitor,
then use a small VGA monitor. Monochrome would be as good but
it's more common for people to be getting rid of their tiny old
VGA monitors.
The hub and wiring needed for the network could be expensive.
But consider -- for years industry and universities got along
fine with 10 Mbit/second (Mbps) service. They ran whole departments
that way and a home network is not likely to need more. Recently,
100 Mbps and 1 Gbps and even wireless service have become popular.
You guessed it. Evey one wants to upgrade even though that old
10 Mbps equipment is still very useful. Cat 3 wiring was usually
used with 10 Mbps service but the 100 Mbps service needs Cat 5
wiring. (Both of these look like telephone wire with Cat 5 being
"better" than Cat 3.) That means usable wiring is getting
disposed of as well. Babbage's basement has begun to get some
of the unwanted hubs and Cat 3 wiring. That's what prompted me
to begin this project.
Checking the Computer
It is time to start your computer. If you are lucky it has
a hard drive with a familiar operating system on it. Mine has
only a floppy drive so I started mine with a
FreeDOS
diskette that I keep for such purposes. As the computer boots
watch for instructions for changing the hardware settings. On
many IBMs, for example, you press F1 during the startup sequence.
Once you have the settings pages up, check everything. Is the
COM port you want to use enabled? Are there interrupts (IRQs)
that are not used and could be used by a network card? IRQ3 or
IRQ5 are often good bets. Unless you are familiar with hardware
settings don't change anything the first time. Just make notes
of what you see. Exit the hardware setup and continue with the
boot process. Is the computer working satisfactorily? If you got
this thing from a junk pile and plugged in some extra memory or
other hardware you may well need to go back and change some of
the hardware settings. FreeDOS comes with a handy little program
called Compinfo that will tell you all sorts of interesting things
about your computer like its processor, amount of memory, disks,
ports, etc.
Finishing the Project
There are two things that need to be done. One is to install
your network cards. You will need one or two for this project
but you may need to install others in order to connect your computers
to the network. The second is to download
Coyote Linux
and make a working diskette. Both are discussed in detail
elsewhere so we provide only the links
Lots of router design
information.
Linux
Ethernet-Howto to learn about network cards for Linux
systems like Coyote.
Coyote FAQ
The other Coyote FAQ
Gene Hartquist, eeh1(at)cornell.edu.
Return to the top of the page.
Volunteering at Babbage's has some interesting rewards for
the person who likes to tinker with things. I needed a computer
in my work area to download drivers and test things like hard-drives,
USB devices, speakers or whatever. So, I built Gene's Funny Box.
The case is an old and very large Gateway 2000 case. There were
two criteria in selecting the case. It had to have as many "half
height" drive bays as possible (this case has four) and it
had to be ATX compatible. The color didn't matter much so after
removing the mother board, power supply and all of the internal
drives I painted it a nice hammer-tone grey. Puce, chartreuse
or pink might have been nice too, but I had an extra can of hammer-tone
paint.
Many of the used computers at Babbage's comply with the
ATX standard.
That means that things like the case, mother board
and power supply are interchangable and that I could scrounge
them from the piles of computers that for one reason or another
could not be refurbished. I found a nice 800 MHz mother board,
a suitable power supply, and a 30 GB hard drive.
The half height drive bays were filled as follows. On top is a
hard drive carrier found cheap at a computerfest flea market. It
has a drawer that allows you to quickly plug in a hard drive for
testing. Next is a half-fast CDRW. Babbage's has lots of those.
Third from the top is a dual 5.25"/3.5" drive from a very old
Gateway desktop computer that was manufactured at about the time
5.25" floppies were going out of style. It is actually possible
to boot this beast from a 5.25" floppy. The fourth is a panel
that brings connections! for sound, USB, game port and firewire
out the front of the box so you don't have to reach around to the
back of the computer to connect things. The last item is a ZIP
100 drive that just fits where the 3.5" floppy drive used to be.
I installed a
Knoppix
operating system. Knoppix is a very popular Linux system based on
Debian Linux. It comes in an astounding collection of readyto use
programs for web-browsing, e-mail, chatting, office work, playing
CDs, DVDs, mp3s, etc, photo manipulation, serving web pages, file
sharing, data-bases and much more. If that is not enough, you can
download and install programs from Debian Linux which boasts more
than 15490 software packages.
Knoppix can be downloaded from the Internet. Start with
downloading a single ".iso" or CD image file and transfer it to a
CD using a CD burning program. (Or you can buy a CD or DVD
already made.) The CD is a "live CD" meaning that you simply put
it in the CD drive and start the computer. The entire system runs
from the CD. It doesn't make any changes to the hard drive at
all, unless you tell it to. If you like what you see and want to
install it on your hard drive follow the instructions you find on
the Knoppix web site. Best of all Knoppix and Debian Linux are
somewhere between very inexpensive and free depending on how you
obtain the software and how much help you need.
Return to the top of the page.
http://babbagesbasement.com/
This web site: 2007 ©
Ted Crane