command for creating virtual interface

Jithu Jance jithujance at gmail.com
Fri Nov 14 05:02:34 EST 2014


Hi Jouni,

Could you share your thoughts on the below replies.

On Mon, Oct 27, 2014 at 8:11 PM, Jithu Jance <jithujance at gmail.com> wrote:
> Hi Jouni,
>
> Thanks for the inputs. Please find my comments inline.
>
>>That patch seems to be adding only WPA_IF_STATION type interfaces which
> would be fine for another station, but maybe not ideal for AP.
>
> Yes. But by setting an AP profile (mode=2), we should be able change
> the role to AP (I tried locally and it works). Having an AP
> concurrently with STA restricts the operation to same channel
> concurrency though.
>
>>Could you please clarify why this functionality should be in wpa_supplicant?
> This would enable us to have an additional wireless IP connection
> (another STA-AP) to another device while the primary STA interface is
> being used for internet connectivity. Since it is the standard virtual
> STA functionality being added, I thought it is good to add support in
> the supplicant.
>
> Basically the sequence I thought of is like as below.
>
> interface_create //creates a virtual network interface
> interface_add //initializes the interface with appropriate conf file
> interface_remove // de-initializes the interface
> interface_del // deletes the network interface.
>
> The virtual interface creation part can be integrated to already
> existing "interface_add" command by adding an additional argument.  I
> just kept the commands separate for testing and getting the initial
> feedback.
>
>>Since driver_nl80211.c is tracking interfaces added and removed through
> if_add() and if_remove() some of these operations triggered by external
> control could result in unexpected results. As such, this does not look
> like the safest way of addressing a need to add/remove a virtual
> interface for independent of internal wpa_supplicant needs.
>
> It might be useful to get the internal status of the peer STA
> interface for later optimizations (to force single channel concurrency
> in case of role change to AP). since interface_add is getting called,
> the newly added STA initialization and connection is controlled via
> supplicant. so internal tracking is useful for this case as well,
> right?
>
> Can some additional checks help to address the safety concern? Like
> for e.g, adding code to remove the externally added interfaces in case
> of a terminate signal.
>
>
> Thanks,
>
>
> - Jithu Jance
>
>
>
>
> On Sat, Oct 25, 2014 at 9:21 PM, Jouni Malinen <j at w1.fi> wrote:
>> On Wed, Oct 22, 2014 at 01:18:35PM +0530, Jithu Jance wrote:
>>> Could you share your thoughts on having commands for virtual interface
>>> creation and deletion?
>>>
>>> I have submitted a patch for the same:
>>> http://patchwork.ozlabs.org/patch/351403/
>>>
>>> The purpose is to create a virtual interface for a secondary STA or
>>> supplicant based AP interface on the fly.
>>
>> That patch seems to be adding only WPA_IF_STATION type interfaces which
>> would be fine for another station, but maybe not ideal for AP. Could you
>> please clarify why this functionality should be in wpa_supplicant?
>>
>> Since driver_nl80211.c is tracking interfaces added and removed through
>> if_add() and if_remove() some of these operations triggered by external
>> control could result in unexpected results. As such, this does not look
>> like the safest way of addressing a need to add/remove a virtual
>> interface for independent of internal wpa_supplicant needs. If I
>> understood the use case correctly, doing this without storing any state
>> in driver_nl80211.c for the interface that was used to remove/add and
>> interface could be more appropriate for this.
>>
>> --
>> Jouni Malinen                                            PGP id EFC895FA
>> _______________________________________________
>> HostAP mailing list
>> HostAP at lists.shmoo.com
>> http://lists.shmoo.com/mailman/listinfo/hostap


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