Re: [Discuss-gnuradio] IEEE802.11 transceiver - problems sending data

[Marcus Müller]

Hi Cristian,

assuming this is a network config issue: On modern Linuxes, it's usually not a great idea to manipulate network config using ifconfig directly – NetworkManager tends to change things automagically if it doesn't think the link is functional (sometimes, even if it is). Please make sure your card is either unmanaged by NetworkManager, or set up the device like you want it to behave, and then activate the connection with `nmcli`. I'm not quite sure this is best solved on the discuss-gnuradio mailing list – we're not really linux networking setup experts :)

Best regards,

Marcus

On 05/26/2017 07:18 AM, Cristian Rodríguez wrote:

2017-05-19 7:04 GMT-05:00 Bastian Bloessl <address@hidden>:

Hi,

> On 19. May 2017, at 12:09, Cristian Rodríguez <address@hiddencom> wrote:
>
>  You will have to also add the corresponding entry in reverse direction. It’s not in the script since I always used the WiFi card of another PC.

> I did that as follows:
>
> sudo arp -s 192.168.123.1 12:34:56:78:90:ab -i wlp4s0

So you just set up one ARP entry.


>
> Then use Wireshark to monitor GNU Radio (that’s what you might do at the moment) and also the WiFi card. This might help to understand what frames are actually sent, if they are OK (MAC, IP, BSS) and if they are successfully received by the WiFi card and the SDR.
> If i do a ping from the interface tap0 to 192.168.123.2 (IP of my wifi card) it doesn't work. The signal is going out of the USRP but the Wifi Card of the computer is not taking it.
>
> ping -I tap0 192.168.123.2
>
> If i do a ping from the interface wlp4s0 to 192.168.123.1 (IP of USRP B210) it doesn't work. The signal is NOT going out of the Wifi card (i verifed that through wireshark).
>
> ping -I wlp4s0 192.168.123.1

As I said, you will have to actually look at the frame (BSS, MAC, IP, …) and see if the fields are OK. Also put the receiver in monitor mode to check if the packet is actually received. It’s a configuration issue and you will have to find out where in the network stack it gets dropped.

I've tried to solve the trouble the whole week. I don't think my computer is able to support the communication between its Wifi card and the USRP B210. When i do a Ping from the USRP to the wifi card (in monitor mode), and it receives the ping, it stops working and in the terminal which is executing the app nic.sh appear ether type: IP. In the wireshark file for the side of Tx, it clearly have stoped working. I've tried to solve it, but i don't think is a configuration problem.

On the other side, i got a computer and i'm try to communicate to it. When i configure Monitor mode i can get packages.

What interface Mode do you think i should use? Ad-hoc or managed?

I've tried both but for me it doesn't work.

I've checked the frame and it looks as supposed. It shows the MAC of the PC which is receiving, the MAC associated to the USRP and the common flags.

I think it is a problem in the configuration file in the PC which is receiving.

In that PC i'm doing the next:

Turn off the interface:

sudo ifconfig wlp2s0 down

Set the mode

sudo iwconfig wlp2s0 mode monitor/managed

Turn on the interface:

sudo ifconfig wlp2s0 up

Set in the channel that USRP is going to send

sudo iw dev wlp2s0 set freq 2472

Assign an IP in the network, the USRP is .1

sudo ifconfig wlp2s0 192.168.123.2

Modify the kernel's IPv4 network

sudo route add -net 192.168.123.0/24 wlp2s0

Set a static route

sudo arp -s 192.168.123.1 12:34:56:78:90:ab -i wlp2s0

All the commands work, i checked with iwconfig, ifconfig, route, arp -a

arp -a

? (192.168.123.1) at 12:34:56:78:90:ab [ether] PERM on wlp2s0

route

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.123.0   *               255.255.255.0   U     0      0        0 wlp2s0

ifconfig

wlp2s0    Link encap:Ethernet  HWaddr e0:ca:94:68:06:a7 
          inet addr:192.168.123.2  Bcast:192.168.123.255  Mask:255.255.255.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1

iwconfig

wlp2s0    IEEE 802.11  ESSID:off/any 
          Mode:Managed  Frequency:2.462 GHz  Access Point: Not-Associated  
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:on

Then i don't catch the problem.

Finally, May you share to me the configuration file that you used when you configure your PC in these experiments?

Really, thanks a lot for your time.

Best regards,

Cristian

 

Best,
Bastian

_______________________________________________
Discuss-gnuradio mailing list
address@hidden
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio