Re: [Discuss-gnuradio] gr-extras: tuntap : How to use ?

[Iain Young, G7III]

On 03/10/12 18:57, Josh Blum wrote:
> On 10/03/2012 10:21 AM, Iain Young, G7III wrote:
>
> > I found the tuntap block, and noticed that it had an input and output.
> > I was expecting my flowgraph to take the userspace end of the network
> > interface, with the other end being the network device.
> >
> > I found the presentation from the recent conference on a basic MAC
> > layer, and that seemed to imply the input could be almost anything,
> > but didn't leave me any the wiser as to exactly how to use it.
>
> Basically, the TUN/TAP block was there for the purposes of replacing
> tunnel.py. Few people *actually* want to pipe stuff through a virtual
> ethernet interface.

Heh, I always did like to be different :)

> For the example, we will probably replace that block with the "socket
> msg" block. You can just open netcat on the host/port and use it like a
> wireless IM chat session :-) There will soon be a demonstration video w/
> the MAC layer stuff presented.

I shall look forward to that


> Instead, try the "socket to blob" block. Outside the flowgraph, open a
> socket and send packets.
>
> > But the input to the tuntap block has confused me. Can I just give
> > it a Null source ? (With the block picking up data from the network
> > device ?)
>
> I pushed a change adding<optional>1</optional>  to the input and output
> ports. You shouldnt need to actually connect.

Great, thanks. Everything now works as expected, and wireshark receives
ethernet frames from my RX tun interface, when I connect the GMSK
Modulator and Demodulator together back-to-back. And yes, it also works
with the Socket-to-Blob blocks :)

Now I just have to figure out what filtering, amplification, levels,
and frequency offsets I need to make it work via my USRP and also
soundcard interfaces.

Not had much success yet, and my rates are somewhat more narrow-band
than most examples out there. Ah well, I'll figure it out at somepoint


Thanks again

Iain