[PLUG] homegrown WAP

[Russell Evans]

On Tue, 11 Nov 2003 16:11:15 -0800
"Carla Schroder" <carla at bratgrrl.com> wrote:

> I'm thinking of building my own wireless access point. The low-cost 
> commercial ones, like Linksys, Netgear, etc. have only a limited 
> browser admin interface. winduhs users get more management utilities, 
> though you still don't get shell access.
> 
> The major concern I have is antenna placement. If I use a PCI wireless

If I was going to buy new equipment I think I would be looking at this
type of product. I know using it to front end a Linux router probably
isn't want it is intended for, but it might work. If is doesn't this I
sure I could use it as it is marketed.

http://www.dlink.com/products/?pid=21

The advantage to using something like this is the Linux box only has to
contain Ethernet cards and do routing. The other plus is the ability to
put the wireless unit where you want, outside.of the computer. The Linux
router could be in the basement with the wireless bridge in the attic
for an extreme case. 

The disadvantage will be using the network in ad-hoc mode. I'm assuming
roaming will be the issue if you have many of the units placed around
the site. Assuming dhcp leases then, I think, it would still be possible
to use. I'm assuming as you left the range of one wireless device and
the link dropped, if the link was established to another wireless unit
that the laptop would request a new dhcp lease and at that point could
be given a new gateway address. 

When I bought into wireless, the price was a little after at the halfway
point of the first consumer wireless stuff. I bought a card for the
laptop and a plx card for the router for about $40 less than a current
AP. I saved about$100-120 at the time using a Linux box. I have had no
issues using it around the house and don't have any dead spots. The
Linux box is upstairs and this probably helps a lot. I don't have a
external antenna, just the stub of the prism card hanging out the back
of the Linux box. 

When I first started looking at this set up I was very confused about
the hostap drivers. The deal with them is that it is set up to use
the Linux bridge. I mistakingly thought that I would need to attach a
Ethernet and the wireless card to the bridge interface. This would have
meant one WAN Ethernet, one Ethernet port for the internal network, one
Ethernet to drop out the wireless segment, and one ethernet port to
bring the dropped wireless back into the firewall / router. So I thought
I would need four Ethernet ports. 

The cool thing is, you can route to the bridge interface. That means
you only have to one interface attached to the bridge, the wireless
segment in my case. So the router only has to have the wireless card
and two Ethernet ports. The bridge port looks like any other device so
you can use iptables on the port. The logical path is wireless to bridge
port, bridge port to iptables, iptables to other Ethernet ports, WAN or
local network. This in was important because I wanted to use a bookpc
that only had two PCI slots and an on board Ethernet port. I thought it
was pretty sweet. 

Thank you
Russell