Re: WPA + IBSS?

[Dan Williams <dcbw redhat com>]

On Fri, 2008-12-12 at 12:08 +0200, Maxim Levitsky wrote:
> On Thu, 2008-12-11 at 23:26 -0500, Dan Williams wrote:
> > On Fri, 2008-12-12 at 04:00 +0200, Maxim Levitsky wrote:
> > > I am testing now the connection sharing feature of NM.
> > > It mostly works, but I found out that I can't create an ad hoc wpa2
> > > protected network. 
> > > Is this possible (nm creates it, but it doesn't work)?
> > 
> > It should be possible, yes, but the first question is "does the driver
> > work?"  This was the major problem when I was actually developing the
> > feature, and I had to go fix the drivers and supplicant to make it work.
> > So, make sure you have at least the following things:
> > 
> > - 2.6.26 or later kernel
> >    * mac80211: the IBSS search interval was too short, plus the stack
> > never notified userspace that it had successfully created the network
> >        872ba53395b2a8be08c3ea2d39e225e5b4a8cb40
> >        507b06d0622480f8026d49a94f86068bb0fd6ed6
> I use 2.6.28-rc7, so I guees that should be included?
> 
> I don't see first commit, but do see second in git history
> 
> 
> > 
> >    * ipw2200: the driver wouldn't expire old BSS entries when creating
> > and IBSS and hit an internal BSS limit
> >        a6d4eae80157830af9c9d80de2daf6611696a34e
> I don't have this driver, iwl3945 here.
> 
> > 
> > - wpa_supplicant 0.6.6 or later
> >    * the wext driver was not correctly downing the interface and
> > bringing it back up again when switching from infra to ibss mode
> >        1d3c75b3b6663ed9f3a9a8dea8d47056cce2680f
> > 
> >    * the ordering of operations after mode switch was wrong
> >        ec5f180a24cd31ba9d3d7f2abc9dc557fd16602f
> > 
> >    * the supplicant wasn't waiting long enough for IBSS creation
> >        1d3c75b3b6663ed9f3a9a8dea8d47056cce2680f
> > 
> I install it soon.
> 
> > Then, see if you can set up a supplicant config that works for you, and
> > if the supplicant can do it correctly, then we have a chance of getting
> > NM to do it correctly.
> > 
> Just curios, what I understand is that wpa_supplicant deals with
> periodic key update, but I have seen that it also scans the network,
> implements roaming, etc..

wpa_supplicant controls wifi devices, irregardless of the "wpa" in the
name.

> Does NM use wpa_supplicant as a wrapper for most its operations, like
> scanning, setting interface settings, like essid ?

Yes, because it's pointless and more complicated to use wpa_supplicant
for WPA stuff and custom code for WEP and unencrypted connections.
Having wpa_supplicant do all of it means only one place has to be fixed
when drivers change or need new features.

> Does nm call wpa_supplicant even while connecting/using to non wpa
> network?

Yes.

> I assume that nm tells all settings to wpa_supplicant via some sort of
> interprocess communication, like socket or fifo, therefore it doesn't
> touch its configuration file, and I guees that by default there is no
> configuration file for wpa_supplicant, right?

Via D-Bus, actually, which you enable with the "-u" option to
wpa_supplicant.  NM uses D-Bus activation to automatically start
wpa_supplicant on demand.

Dan