[systemd-devel] udev breaks hostap linkage of raw/user interfaces, causing wpa_supplicant problems

[David Herrmann]

Hi

On Mon, Mar 16, 2015 at 5:35 PM, Michael Biebl <mbiebl at gmail.com> wrote:
> 2015-03-16 17:25 GMT+01:00 David Herrmann <dh.herrmann at gmail.com>:
>> Hi
>>
>> On Mon, Mar 16, 2015 at 4:48 PM, Thomas Richter <thor at math.tu-berlin.de> wrote:
>>> If udev comes into play, it renames wlan0 to wlan1, because wlan0 was
>>> already taken from a previously installed ipw2200 card that is no longer
>>> in the system. Hence, I have now the network interfaces wifi0 and wlan1,
>>> and that confuses wpa_supplicant to an amount that it can no longer
>>> authenticate the connection. Why precisely that is the case I do not
>>> know, but naming both interfaces the same resolves the problem.
>>
>> Ok, forget my previous mail, your issue is only related to the wext
>> driver, not the hostap extensions.
>>
>> Up front, upstream udev never renames wlan0 to wlan1.
>
> Well, "current" upstream udev, with persistent interface naming
> enabled, would rename italso, it would just chose a different name,
> one which is not in the same wlanX namespace.
> If that alone is suffcient to not trigger Thomas problem, I dunno.

If it's not named "wlanX" the bug will not appear. Please have a look
at hostap-git/src/driver_wext.c wpa_driver_wext_finish_drv_init() as
mentioned in my previous mail.

> That said, Thomas is talking about udev 175 (Debian wheezy), where
> udev upstream did infact still ship the udev rules which renamed wlan
> interface within the same namespace.
>
>  This is a
>> downstream problem.
>
> Please don't be so quick always blaming downstream.

Ok.

Thanks
David