Re: Looking for a wireless ethernet solution...
On Thu, 30 Aug 2001, Joey Hess wrote:
[...]
> This would require you also buy a pcmcia adapter for your linux box,
> since all the networking gear comes pretty much as pcmcia cards. I
> believe that the access points don't come with a pcmcia card either, so
> you'll need three in all. Gear list then comes down to (you may find
> slightly better prices):
The access point does not need a pcmcia card. All the electronics for
doing wireless stuff is already included. So the list would become:
$150+ 1 access point
$75 1 pcmcia to ISA or pcmcia to PCI bridge
$210 2 pcmcia cards
$435 total
But the prices I have seen are a bit higher: usually around $250 for
the access point and $150 for each pcmcia card. This raises the total
cost to $625.
> Here is an alternative:
>
> windows laptop
> | .
> | .
> hub ------------- linux box ---- dsl
> | .
> | .
> friend's box .
> guy in a van on the street
>
> Here you keep the wired link between the linux box and the hub to the
> windows box, and do not use an access point, instead using Ah-Hoc
> networking mode between your linux box and the laptop. This requires
> only 2 pcmcia cards, so the gear is:
>
> $75 1 pcmcia to ISA or pcmcia to PCI bridge
> $140 2 pcmcia cards
> $215 total
Or $375.
But there is a problem with this solution: you need 3 available PCI
slots. One for the wireless card, one for the ethernet card to the hub,
and one for the ethernet card to the dsl.
I'm also thinking about getting a wireless setup and this has kind of
blocked me for now. But there may be an alternative. The traffic between
the dsl and the linux box is likely to be PPP: PPPoE. And some access
points can even speak PPP on their wired side. So the idea is to
basically connect everything to the hub.
dsl
|
windows ---+ (ppp)
| |
friend's box ---+--(ethernet)-- hub
| |
linux box ---+ (ppp)
|
laptop . . . . . access point . . . . . guy in a van
The idea is that the PPP traffic would be relayed from the access
point and dsl to the linux box (and all others) and that the linux box
would pick it up there.
This should be safe in that the 'guy in the van' cannot scan your
network since all the access point spits out on your lan is PPP packets.
The only security risk is that anyone on the lan can snoop on this
traffic, but this may be deemed acceptable.
Same for the DSL.
But there's a couple of big question marks there:
* can an ethernet hub relay PPP traffic?
* what about a switch (I have a switch at home)
* will the PPP traffic and the IP traffic interfer
* in the case of the access point, the access point is expecting the
linux box to play the role of a dsl modem. Is there software that can
handle that on Linux?
* PPP is a point to point protocol. Will it work to have two such
devices share just one ethernet segment? (if not we can still put the
dsl on it which still saves a PCI slot)
Oh, and yes, this is probably much more complex. But you get to play
with Linux firewalling, auto-proxying, ...
And to complete the picture I would use the wireless network in
unencrypted mode so that anyone can access it (and since the 802.11
encryption is relatively useless anyway), but only allow access to the
internet (firewalled to prevent too nasty things from happening). Then I
would use a VPN between the laptop and the linux box, and would only
allow the traffic from this VPN to access the LAN.
--
Francois Gouget fgouget@free.fr http://fgouget.free.fr/
War doesn't determine who's right. War determines who's left.
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