Re: Interfacing mac802154 stack with userspace applications

[Alexander Aring <alex.aring@gmail.com>]

Hi Victhor,

On Fri, Oct 25, 2019 at 6:39 PM Victhor Foster <victhor.foster@ufpe.br> wrote:
>
> Hello,
>
> I'm working on a project to implement a 6LoWPAN network using software defined radios. I'm trying to interface the kernel's 802.15.4/6LoWPAN stacks to my physical layer implemented in GNU Radio, instead of using a userspace stack, but this isn't working very well.
>
> The reason why I'm doing this is, while the GNU Radio plugin I'm using (gr-ieee802-15-4 from Bastian Bloessl) implements its own 802.15.4 MAC layer, I'd like to get around its limitations (such as not being able to change destination addresses at runtime) using the Linux kernel stack.
>

It's possible to change the destination address. Do you use af802154?

> The way this is being done is I have socat piping between a mac802154_hwsim interface and GNU Radio, using the following arguments: INTERFACE:wpan0 UDP4-DATAGRAM:127.0.0.1:<port>
> GNU Radio is running a UDP server at <port> that transmits and receives PDUs to/from the software defined PHY, which then goes out to a software defined radio device (a USRP N210, in this case). So the PDUs are sent via the socat pipe to the hwsim network interface and vice-versa. The 802.15.4 MAC block is removed.
>
> While 802.15.4 packets are sent and received by both hosts, it seems these packets aren't getting through to the 6LoWPAN stack.
>
Mhh, do you can provide more information about the setup so I can test
it on my own? Do you took care about channel/page and panid settings?


> During testing, I had packet capture set up on both the 802.15.4 ("wpan0") and the 6LoWPAN ("lowpan0") interfaces. The wpan0 interface was receiving packets from the other host (and also from itself, as the radio is full duplex), as expected. However, I could not get wpan-ping to work (timeout) and ping6, netcat, etc. wouldn't get a response from the other host.
> On the lowpan0 interface, I could see the packets originating from applications would appear on the packet capture log, but those that should be coming from the wpan0 interface wouldn't, even those originating from the host itself (due to the full duplex nature of the radio).
>

No idea, this is now your gnuradio device?

> I also noticed the following message on the kernel log: ieee802154 phy0 wpan0: encryption failed: -22
> I haven't touched the link encryption settings, so the traffic is unencrypted.

This looks that you receive encrypted frames, it might be only the
frame control field is misleading and security is enabled, can you
check?

>
> What could be done to get the 6LoWPAN stack to accept packets injected into the 802.15.4 interface by socat? I realize this is a very unusual situation, but I'm not familiar with the Linux 802.15.4 stack.

No idea, sorry for my late reply. Can you provide more information?

- Alex