Fwd: [ipw3945-devel] Monitor mode on boot

Fwd: [ipw3945-devel] Monitor mode on boot

[Stefanik Gábor]

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---------- Forwarded message ----------
=46rom: Stefanik G=E1bor <netrolller.3d@gmail.com>
Date: Fri, May 16, 2008 at 4:03 PM
Subject: Re: [ipw3945-devel] Monitor mode on boot
To: Martin Dubuc <martind1111@gmail.com>
Cc: ipw3945-devel@lists.sourceforge.net, linux-wireless@vger.kernel.org


On Fri, May 16, 2008 at 3:27 PM, Martin Dubuc <martind1111@gmail.com> w=
rote:
>
> You are right pointing out that it is possible to perform monitor mod=
e configuration using startup scripts. However, to fit nicely in existi=
ng frameworks, such as the ones available from Fedora, it would be nice=
 that the driver be enhanced. Madwifi allows users to put a configurati=
on like this one in the modprobe.conf.:
>
> options ath_pci autocreate=3Dmonitor
>
> The nice thing about such a configuration is that it decouples the de=
vice type configuration from the interface management function. One doe=
s not need to worry which interface (wlan0, wlan1, wlan2, etc.) a devic=
e will come up on, the system configures any device of a given type usi=
ng a common set of configuration. For systems that have only one Wi-Fi =
device, your method is as good as this one, but for systems that have m=
ore than one Wi-Fi device, some of them coming off and on while the sys=
tem is running, possibly using different interface names, the modprobe.=
conf solution is better.
>
> Martin


This might better be done in the stack, rather than the driver. This
way, all drivers would get this functionality. CCing the
linux-wireless mailing list.
Also, since an userspace solution might be preferred by Linville and
the other wireless maintainers, it might be wise to add an "aggregate
device" or a "supermaster" which can be targeted by iw so that all
devices governed by that driver get a new interface.
Alternatively, a script can be made that creates a monitor interface
on monX or rtapX for all wmasterX devices. This is equivalent to
madwifi's solution, except that it's userspace, which is preferred
now.

--
Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)


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Re: [ipw3945-devel] Monitor mode on boot

[Stefanik Gábor]

On Fri, May 16, 2008 at 4:03 PM, Stefanik G=E1bor <netrolller.3d@gmail.=
com> wrote:
> On Fri, May 16, 2008 at 3:27 PM, Martin Dubuc <martind1111@gmail.com>=
 wrote:
>>
>> You are right pointing out that it is possible to perform monitor mo=
de
>> configuration using startup scripts. However, to fit nicely in exist=
ing
>> frameworks, such as the ones available from Fedora, it would be nice=
 that
>> the driver be enhanced. Madwifi allows users to put a configuration =
like
>> this one in the modprobe.conf.:
>>
>> options ath_pci autocreate=3Dmonitor
>>
>> The nice thing about such a configuration is that it decouples the d=
evice
>> type configuration from the interface management function. One does =
not need
>> to worry which interface (wlan0, wlan1, wlan2, etc.) a device will c=
ome up
>> on, the system configures any device of a given type using a common =
set of
>> configuration. For systems that have only one Wi-Fi device, your met=
hod is
>> as good as this one, but for systems that have more than one Wi-Fi d=
evice,
>> some of them coming off and on while the system is running, possibly=
 using
>> different interface names, the modprobe.conf solution is better.
>>
>> Martin
>
>
> This might better be done in the stack, rather than the driver. This =
way,
> all drivers would get this functionality. CCing the linux-wireless ma=
iling
> list.
> Also, since an userspace solution might be preferred by Linville and =
the
> other wireless maintainers, it might be wise to add an "aggregate dev=
ice" or
> a "supermaster" which can be targeted by iw so that all devices gover=
ned by
> that driver get a new interface.
> Alternatively, a script can be made that creates a monitor interface =
on monX
> or rtapX for all wmasterX devices. This is equivalent to madwifi's so=
lution,
> except that it's userspace, which is preferred now.
>
> --
> Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)

BTW, here is a script that automatically creates a "monX" interface
for every "wmasterX" master device it encounters:

#!/bin/sh
for a in $(iwconfig 2>&1 | grep wmaster | sed -e 's/wmaster//' | cut -b=
 1); do
iw dev wmaster$a interface add mon$a type monitor
ifconfig mon$a up
done

--=20
Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)
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Re: [ipw3945-devel] Monitor mode on boot

[Stefanik Gábor]

On Fri, May 16, 2008 at 4:28 PM, Stefanik G=E1bor <netrolller.3d@gmail.=
com> wrote:
> On Fri, May 16, 2008 at 4:03 PM, Stefanik G=E1bor <netrolller.3d@gmai=
l.com> wrote:
>> On Fri, May 16, 2008 at 3:27 PM, Martin Dubuc <martind1111@gmail.com=
> wrote:
>>>
>>> You are right pointing out that it is possible to perform monitor m=
ode
>>> configuration using startup scripts. However, to fit nicely in exis=
ting
>>> frameworks, such as the ones available from Fedora, it would be nic=
e that
>>> the driver be enhanced. Madwifi allows users to put a configuration=
 like
>>> this one in the modprobe.conf.:
>>>
>>> options ath_pci autocreate=3Dmonitor
>>>
>>> The nice thing about such a configuration is that it decouples the =
device
>>> type configuration from the interface management function. One does=
 not need
>>> to worry which interface (wlan0, wlan1, wlan2, etc.) a device will =
come up
>>> on, the system configures any device of a given type using a common=
 set of
>>> configuration. For systems that have only one Wi-Fi device, your me=
thod is
>>> as good as this one, but for systems that have more than one Wi-Fi =
device,
>>> some of them coming off and on while the system is running, possibl=
y using
>>> different interface names, the modprobe.conf solution is better.
>>>
>>> Martin
>>
>>
>> This might better be done in the stack, rather than the driver. This=
 way,
>> all drivers would get this functionality. CCing the linux-wireless m=
ailing
>> list.
>> Also, since an userspace solution might be preferred by Linville and=
 the
>> other wireless maintainers, it might be wise to add an "aggregate de=
vice" or
>> a "supermaster" which can be targeted by iw so that all devices gove=
rned by
>> that driver get a new interface.
>> Alternatively, a script can be made that creates a monitor interface=
 on monX
>> or rtapX for all wmasterX devices. This is equivalent to madwifi's s=
olution,
>> except that it's userspace, which is preferred now.
>>
>> --
>> Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-=
)
>
> BTW, here is a script that automatically creates a "monX" interface
> for every "wmasterX" master device it encounters:
>
> #!/bin/sh
> for a in $(iwconfig 2>&1 | grep wmaster | sed -e 's/wmaster//' | cut =
-b 1); do
> iw dev wmaster$a interface add mon$a type monitor
> ifconfig mon$a up
> done
>
> --
> Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)
>

Oops... this is enough:
#!/bin/sh
for a in $(iwconfig 2>&1 | grep wmaster | cut -b 8); do
iw dev wmaster$a interface add mon$a type monitor
ifconfig mon$a up
done

--=20
Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)
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Re: [ipw3945-devel] Monitor mode on boot

[John W. Linville]

On Fri, May 16, 2008 at 04:03:15PM +0200, Stefanik G=E1bor wrote:
> On Fri, May 16, 2008 at 3:27 PM, Martin Dubuc <martind1111@gmail.com>=
 wrote:
>=20
> > You are right pointing out that it is possible to perform monitor m=
ode
> > configuration using startup scripts. However, to fit nicely in exis=
ting
> > frameworks, such as the ones available from Fedora, it would be nic=
e that
> > the driver be enhanced. Madwifi allows users to put a configuration=
 like
> > this one in the modprobe.conf.:
> >
> > options ath_pci autocreate=3Dmonitor
> >
> > The nice thing about such a configuration is that it decouples the =
device
> > type configuration from the interface management function. One does=
 not need
> > to worry which interface (wlan0, wlan1, wlan2, etc.) a device will =
come up
> > on, the system configures any device of a given type using a common=
 set of
> > configuration. For systems that have only one Wi-Fi device, your me=
thod is
> > as good as this one, but for systems that have more than one Wi-Fi =
device,
> > some of them coming off and on while the system is running, possibl=
y using
> > different interface names, the modprobe.conf solution is better.
> >
> > Martin
> >
> >
> This might better be done in the stack, rather than the driver. This =
way,
> all drivers would get this functionality. CCing the linux-wireless ma=
iling
> list.

In general I think we would like to avoid module options, especially
in cases where the userland equivalent is easily accomplished.
But if this is truly warranted it would make more sense to put it
into mac80211 than into an individual driver.

Why would you want to automatically create several monitor interfaces
on the same box?  Won't this usually be more-or-less redundant?

> Also, since an userspace solution might be preferred by Linville and =
the
> other wireless maintainers, it might be wise to add an "aggregate dev=
ice" or
> a "supermaster" which can be targeted by iw so that all devices gover=
ned by
> that driver get a new interface.

Gack!  The last thing I would want to see is more magical netdevs
with mysterious purposes...

> Alternatively, a script can be made that creates a monitor interface =
on monX
> or rtapX for all wmasterX devices. This is equivalent to madwifi's so=
lution,
> except that it's userspace, which is preferred now.

The scripts later in the thread seem simple enough.  Do they suffice?

John
--=20
John W. Linville
linville@tuxdriver.com
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Re: [ipw3945-devel] Monitor mode on boot

[Stefanik Gábor]

On Fri, May 16, 2008 at 6:06 PM, Martin Dubuc <martind1111@gmail.com> wrote:
> John,
>
> I do not believe the script later in the thread will suffice. As far as I
> can understand, the script will create one interface in monitor mode for
> each wmasterX (which is good), but the system will also bring up one managed
> mode interfaces in parallel for each wmasterX. In my use case, I only want
> an interface of device type X to come up in monitor mode and I don't want a
> managed mode interface created in parallel.
>
> I need to create multiple monitor interfaces on the same box because my
> application dedicates interfaces for the capture of traffic on specific
> channels.
>
> Martin

Why is the existence of managed interfaces a problem? Unlike madwifi,
mac80211 really supports multiple interfaces on one device.

-- 
Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)

Re: [ipw3945-devel] Monitor mode on boot

[Stefanik Gábor]

On Fri, May 16, 2008 at 6:26 PM, Martin Dubuc <martind1111@gmail.com> wrote:
> My application uses some of the Wi-Fi interfaces strictly for survey
> purposes and in these cases, there is no need to connect to any access point
> on the same wmasterX. To maximize resource usage, I would like to avoid to
> have managed interface created for these interfaces.
>
> Martin

This script should do it:
#!/bin/sh
for b in $(find /sys/class/net/*/* -name phy80211 | grep -v wmaster |
sed -e 's/\/phy80211//' | sed -e 's/\/sys\/class\/net\///'); do
iw dev $b interface del
done
for a in $(iwconfig 2>&1 | grep wmaster | sed -e 's/wmaster//' | cut -b 1); do
iw dev wmaster$a interface add mon$a type monitor
ifconfig mon$a up
done

-- 
Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)

Re: [ipw3945-devel] Monitor mode on boot

[John W. Linville]

On Fri, May 16, 2008 at 12:48:26PM -0400, Martin Dubuc wrote:
> This would solve the boot up issue, but probably not the case where
> interfaces are added after the system is booted up (USB or PCI cards that
> can be hot plugged).

udev?

-- 
John W. Linville
linville@tuxdriver.com

Re: [ipw3945-devel] Monitor mode on boot

[Johannes Berg]

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On Fri, 2008-05-16 at 13:27 -0400, John W. Linville wrote:
> On Fri, May 16, 2008 at 12:48:26PM -0400, Martin Dubuc wrote:
> > This would solve the boot up issue, but probably not the case where
> > interfaces are added after the system is booted up (USB or PCI cards that
> > can be hot plugged).
> 
> udev?

Yeah, I was just about to suggest the same. Learn how to use userspace
tools, we're not going to do it in the kernel no matter how much you
cry :)

johannes

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