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Hack 51 Do-It-Yourself Access Point Hardware

Use one of these popular embedded PC boxes as a
building block for your access point project.

There is a huge variety of
PC-compatible hardware available that is perfectly capable of serving
as an access point. If budget is a concern, you can certainly dust
off that old PC that is collecting dust in the closet (provided that
it is roughly of 486/50 vintage or so; 386 machines, while nostalgic,
are probably too painfully slow to deal with by
today's standards). Some people choose to use a
full-blown tower case with an old 486 or Pentium processor as a
combination access point and file server. One node on the NoCat
network is an old Apple G3 running Yellow Dog Linux, as that was what
we had lying around!

But if you are planning on building out a large network project, it
is advisable to standardize your hardware platform. This is a good
idea from an aesthetic point of view, as well as for reliability and
ease of troubleshooting. While your dusty old 486 might be just
taking up space, brand new embedded machines are coming down in
price. These are tiny, fanless machines that are designed to run off
of DC power, which boot from cheap compact flash RAM. This means no
moving parts, simple ventilation requirements, and potentially very
long uptimes.

Not all embedded solutions are necessarily cost effective. One
notorious example is the PC/104 hardware used in industrial
applications. Although it offers relatively low performance, this
hardware has a reputation for robustness and ease of programming, as
well as the standard PC/104
"stackable" bus. But even its
extreme popularity in the industrial world hasn't
done much to bring down its price, relative to what is available in
the general purpose computing world.

Whatever hardware platform you choose, be sure that it meets your
needs. When choosing a piece of hardware, you should remember to
consider the number and type of radio and network interfaces, cooling
and power requirements, size, RAM and CPU available, and of course,
cost. Here are a number of solutions that DIY networks have found to
bring a high performance-to-price ratio.

Soekris (http://www.soekris.com/)

Affectionately known as the
"little green box," the Soekris
solution is a popular choice among do-it-yourself networkers. There
are a number of Soekris models that work well as access points, with
and without PCMCIA. All Soekris boards will boot from Compact Flash
and come standard with multiple Ethernet interfaces, a mini-PCI slot,
hardware watchdog, serial console, and an AMD 133 MHz processor. They
are all fanless boards and use a DC power supply (see Figure 4-11).

At the time of this writing, the Soekris net4521 (with two PCMCIA
slots, two Ethernet ports, a mini-PCI slot, and 64 MB RAM) sells for
about $250.

OpenBrick (http://www.openbrick.org/)

Another popular embedded solution is
the OpenBrick. The typical OpenBrick has a 300 MHz (fanless) Geode
processor, an on-board NIC, a PCMCIA slot, and boots from Compact
Flash. It runs on DC power, and unlike the Soekris, also has USB
ports (although it does not have a mini-PCI slot.) It comes standard
with 128 MB RAM, and also has room for a 2.5" hard drive.

The OpenBrick (Figure 4-12) is designed to serve as
a tiny server or client workstation, and as such, has virtually all
standard PC functionality (VGA and NTSC video out, PS/2, parallel and
serial ports, audio, etc.). Its additional features also make for a
higher price tag, with the going rate about $360 as of this writing.

Via-based computers (http://www.via.com.tw/)

There are
a number of Via-based computers on the market. They are generally
marked as desktop PCs, although small, fanless cases that take a DC
power supply are becoming commonplace. As they are intended to be
used as general purpose PCs, they typically have 500 MHz or better
Via processors, on-board NICs, an IDE interface, USB, and a PCI slot.
Using an inexpensive CF-to-IDE adapter[Hack #52], these boards (or,
indeed, any PC) can be made to boot from Compact Flash for a hardware
solution with no moving parts.

If you are looking for a fanless solution, be sure to get the 500 MHz
version, as the 800 MHz and faster Via boards require a processor
fan. Via motherboards (Figure 4-13) are around $100
at the time of this writing, without case, RAM, or storage.

The Fujitsu Stylistic series

This collection simply
wouldn't be complete without mentioning the
Fujitsu Stylistic 1000 series (Figure 4-14). This is a very popular surplus market tablet
PC that has "hack me" written all
over it. It has three PCMCIA slots, one of which is the boot device.
It can boot from Card Flash using a CF to PCMCIA adapter, and is unique in
that it has an integrated LCD display and battery. The 1000 series
has a 486 DX4/100 processor, is expandable to 40 MB RAM, can use a
cordless pen for input, and has served just fine as a hardware
gateway (I use one myself for my node on SeattleWireless). Fujitsu
still makes the Stylistic series, although new machines are quite
expensive (on par with modern laptops). The older 1000s or 1200s can
frequently be found on the surplus market for less than $100.

Running your own custom access point can be considerably more
challenging than the plug-and-play devices you can buy in consumer
electronic stores, but building such devices can be much more
rewarding as well. Bringing the power and flexibility of Linux or BSD
to the access point itself can lead to all sorts of interesting
possibilities that just can't be accomplished with a
$75 over-the-counter access point.