Reading the current monitor flags of an interface

Reading the current monitor flags of an interface

[Roger James]

Hi,

I am trying to get at the current monitor flags setting of a wireless 
monitor mode virtual interface. I have tried to do this by hacking the 
iw source. However I never see a NL80211_ATTR_MNTR_FLAGS attribute 
returned in response to the

TOPLEVEL(info, NULL, NL80211_CMD_GET_INTERFACE, 0, CIB_NETDEV, 
handle_interface_info,
      "Show information for this interface.");

command in iw's interface.c code.

Questions.

1. Am I wasting my time? (e.g. the rt2800usb driver never returns this 
info, or there is another easy way of viewing this info, etc)

2. Am I doing something stupid? (e.g. I need to specify some additional 
flags to the get command.)

3. Has anybody else tried this before?

All help will be gratefully received.

Roger

Re: Reading the current monitor flags of an interface

[Johannes Berg]

On Sat, 2016-01-02 at 16:27 +0000, Roger James wrote:
> Hi,
> 
> I am trying to get at the current monitor flags setting of a wireless
> monitor mode virtual interface. I have tried to do this by hacking
> the 
> iw source. However I never see a NL80211_ATTR_MNTR_FLAGS attribute 
> returned in response to the
> 
> TOPLEVEL(info, NULL, NL80211_CMD_GET_INTERFACE, 0, CIB_NETDEV, 
> handle_interface_info,
>       "Show information for this interface.");
> 
> command in iw's interface.c code.
> 
> Questions.
> 
> 1. Am I wasting my time? (e.g. the rt2800usb driver never returns
> this 
> info, or there is another easy way of viewing this info, etc)
> 

Looks like it's never set in the corresponding kernel code.

johannes

Re: Reading the current monitor flags of an interface

[Roger James]

On 05/01/16 16:02, Johannes Berg wrote:
> On Sat, 2016-01-02 at 16:27 +0000, Roger James wrote:
>> Hi,
>>
>> I am trying to get at the current monitor flags setting of a wireless
>> monitor mode virtual interface. I have tried to do this by hacking
>> the
>> iw source. However I never see a NL80211_ATTR_MNTR_FLAGS attribute
>> returned in response to the
>>
>> TOPLEVEL(info, NULL, NL80211_CMD_GET_INTERFACE, 0, CIB_NETDEV,
>> handle_interface_info,
>>        "Show information for this interface.");
>>
>> command in iw's interface.c code.
>>
>> Questions.
>>
>> 1. Am I wasting my time? (e.g. the rt2800usb driver never returns
>> this
>> info, or there is another easy way of viewing this info, etc)
>>
> Looks like it's never set in the corresponding kernel code.
>
> johannes
> --
> To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
Thanks Johannes, that was my conclusion, but I was not sure if that was 
true in all cases. I tried another chipset and got the same results. I 
am trying to debug a problem with an adapter only seeing broadcast and 
multicast packets in monitor mode, and the significance of the setting 
of the  otherbss flag in this case. It would be really helpful if iw 
could return the complete state of an interface, but it looks like that 
would require a kernel patch. This seems like a can of worms to me.

Roger

Re: Reading the current monitor flags of an interface

[Johannes Berg]

On Tue, 2016-01-05 at 16:19 +0000, Roger James wrote:
> 
> Thanks Johannes, that was my conclusion, but I was not sure if that was 
> true in all cases. I tried another chipset and got the same results. 

It is true in all cases, since it's the generic cfg80211 code not doing
this. It's not even storing the flags, so it's not a trivial patch.

> I 
> am trying to debug a problem with an adapter only seeing broadcast and 
> multicast packets in monitor mode, and the significance of the setting 
> of the  otherbss flag in this case. It would be really helpful if iw
> could return the complete state of an interface, but it looks like that 
> would require a kernel patch. This seems like a can of worms to me.

It's not trivial, agree, since you'd have to query the underlying
driver (mac80211) for the flags.

johannes