From: Tomi Manninen OH2BNS (dpbqfl@relay.tunkki.fi)
Date: Mon Jan 03 2000 - 15:27:47 EET
On Wed, 29 Dec 1999, Dirk Koopman wrote:
> 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.
Some kind of braodcast/multicast method should probably be added to the
AX.25 stack. But if you want that much flexibility it might be easiest to
really use PF_PACKET. Sure you need root for that but only when calling
socket().
> 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.
Calling socket(PF_AX25, SOCK_RAW, ...) doesn't require root but then
binding the socket to any local address other than your own does require
it.
> 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.
SOCK_RAW with AX25 seems to be just about the same as SOCK_DGRAM except
that when you receive you get the PID byte as well. Thus I'm not sure if
it's really very usefull.
-- --- Tomi Manninen / osvo@roskapostia.tunk.net / OH2BNS @ OH2RBI.FIN.EU ---
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