wpa_supplicant with bridge

Bob Carlson rjc at sigpro.com
Tue May 16 11:29:59 EDT 2006


I have used wpa_supplicant embedded in an Atheros based AP that is being
used as a client acting as a bridge. So my situation is similar to yours,
but I am not working with madwifi or Linux at all.

WPA-PSK is really independent of the use of the link as a bridge. However,
there are a lot of places where Atheros and other vendors have not
supported bridging well. One AP I know of that works reasonably well is the
D-Link DWL 2100. It supports WDS along with WPA1. (It implements AES only
using WPA1 formats if that means anything to you.) WMM is NOT supported,
however.

Cheers, Bob

> -----Original Message-----
> From: hostap-bounces+bob.carlson=sigpro.com at shmoo.com [mailto:hostap-
> bounces+bob.carlson=sigpro.com at shmoo.com] On Behalf Of Chris Baechle
> Sent: Tuesday, May 16, 2006 9:57 AM
> To: hostap at shmoo.com
> Subject: wpa_supplicant with bridge
> 
> Scenerio:
> 
> We've got a remote house a few hundred yards away that needs internet
> access. Running cable would be way too much work for so few computers.
> Our idea was to create a bridge. One interface wired and the other
> interface wireless. This way we can have 4 computers going into a
> switch, which goes into the bridging computer (wired), goes out
> wireless to the AP.
> 
> Well, we got it to work with an atheros based (madwifi) card and brctl.
> 
> Now it's time to secure it with WPA-PSK...
> 
> Looking through the lists, it seems the latest stable version of
> wpa_supplicant (0.4.9) doesn't support bridging. However, 0.5.3's
> README indicates an -b argument (for bridging) which seems to be
> exactly what I want.
> 
> Great, right? Well, not exactly. 0.4.9 precompiled fedora version
> works fine with my madwifi (just as a regular client). My 0.5.3
> compile goes into an infinite loop where it connects for a second,
> then disconnects (again, not even bothering with bridging yet. Just as
> a regular client). My AP doesn't support logging so I don't know if it
> was ever a real successful connect. But if I refresh iwconfig fast
> enough it'll show me as being associated for a second, then not. I
> tried debian unstable with the wpasupplicant experimental package with
> the same exact results (as well as my own 0.5.3 compile). Looking
> through the list, it seems at one point someone had the exact same
> issue. It was suggested maybe it's a bug at the madwifi level, but
> that's where the discussion ended.
> 
> So now it's question time.
>  - Am I correct in assuming 0.4.9 doesn't support what I'm trying to
> do (bridging)?
> - Does the -b option in 0.5.3 actually accomplish what I'm trying to do?
> - Are there any known issues with madwifi and wpa_supplicant?
> - Has anyone ever accomplished what I'm trying to do with
> wpa_supplicant and _any_ wireless card?
> - Can any other linux/*bsd supplicant achieve bridging in this manner?
> 
> I suppose if I absolutly have to I can NAT. I'd rather not as the
> outbound connection is already double natted and we are trying to get
> it down to single NAT. My other option would be Proxy ARP. But really,
> I'd rather do it this way because it will be best for our setup.
> 
> If need be I can sponsor (monitarily) any bug fixing to get this to
> work because we have a few more places we'd be able to use this and
> would be extremely useful to us.
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