Re: ax.25 and broadcast/multicast

From: Tomi Manninen OH2BNS (mkjrdx@chello062179050121.chello.pl)
Date: Thu Jan 04 2001 - 15:28:28 EET

  • Next message: Tomi Manninen OH2BNS: "Re: Two ax25 driver-level problems -- help?"

    On Thu, 4 Jan 2001, Chris Leishman wrote:

    > Hi all,
    >
    > According to the AX.25 Link-Layer Protocol Description, it is possible to do
    > "multicast" style transmission, where the destination callsign is a code word
    > that the receivers listen for.

    > I'm trying to work out how you can configure the linux device to receive
    > packets destined for that callsign (in addition to it's normal callsign) and I
    > can't seem to see it in the HOWTO's, etc.

    You can receive UI frames with a specific destination address by opening
    a RAW socket (fd = socket(PF_AX25, SOCK_RAW, AX25_P_TEXT)), binding the
    socket to the wanted address via port address ("PACKET via N0CALL" where
    N0CALL is the HW address of the port in question) and then doing a
    recvfrom(fd, ..., &from, ...). You get the senders callsign and the digi
    path used in the from argument. Note however that in kernels prior to
    2.2.15 recvfrom actually returns the wrong address. 

    -- 
Tomi Manninen           Internet:  erxmbi.xxglzhf@nine.com.au
OH2BNS                  AX.25:     bbxi.bgzblfidn@accessus.net
KP20ME04                Amprnet:   zvvygt@hsc.edu

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