On 28-Dec-1999 Tomi Manninen wrote:
>> I want to implement a UI based DX
>> Cluster protocol so that, finally, we can move on a bit, reduce some
>> bandwidth and maybe even achieve some experimentation. In order to do that
>> I
>> need to be able to send UI frames from my callsign to any address, listen
>> for
>> UI frames from any address, to any address and process the ones I am
>> interested in (only a few of which will be addressed to me) and maybe (for
>> experimental purposes) relay some frames from one interface to another.
> 
> Explain me why you need to receive UI frames addressed to any address? FBB
> uses a UI based message system and copes well with only UI frames
> addressed to the box call.
> 

Because I wish to receive packets addressed to generalised, as it were,
"broadcast" addresses eg "DX", "ANN", "LINK" (these are examples, not
necessarily real) as well as to my callsign. I also may want to gateway UI
frames to callsigns that I know (by various higher level means) to be part of
"my" network (i.e to "digi" UI frames selectively across ports according to
heuristics under my control).

The point of this that a reliable multicast protocol requires there to be
some group addresses, for DX cluster work there are several logical
groups that one could envisage including, but not limited to, "node-to-user"
things, "network" things, "inter-user" things and so on. As well as
multicast, there is a point to point message requirement that could be done
by "normal" connected mode but I would prefer, for orthogonality, to also be
done by a simple UI based, window=1, protocol.

I was not envisaging a PF_PACKET based thing - I understand why this is a
problem. I was under the impression that we were talking about SOCK_RAW here
and that that required root as well.

Have you any sample code that does things with SOCK_RAW? I am perfectly happy
to generate raw AX25 packets (I can do that bit), it is the ioctl and
socket magic that I am confused (and cannot find any documentation for
SOCK_RAW) about. 

Dirk G1TLH
-- 
Dirk-Jan Koopman, Tobit Computer Co Ltd 
At the source of every error which is blamed on the computer you will find
at least two human errors, including the error of blaming it on the computer.

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