lost dump ?!?!?

Alex Badea vamposdecampos at gmail.com
Fri May 6 06:35:50 UTC 2011

On Thu, May 5, 2011 at 5:28 PM, screaming-pain at libero.it
<screaming-pain at libero.it> wrote:
> Hi list,
> I know I am very slow in understanding osmocom-bb, anyway this is just a quick
> question.
> Is it possible that some of the gsmtap messages are getting lost?
> For example I can see a LOCATION UPDATE and a LOCATION ACCEPT from the
> 'mobile' application log but there aren't the corresponding messages in the
> wireshark capture,
> though this does not always happen, I mean I had captures of location updates
> other times, this is why I am wondering if they are getting lost and what it
> does depend on.
> for what I understood the gsmtap functions utilities are in gsmtap_util.c and
> the one to send the messages on the socket is called by l1ctl.c am I right?
> Can you help me understanding why I cannot see all the messages?
> thank you in advance
> Loretta


I've had this happen to me when I wasn't receiving the gsmtap packets.

Specifically, I had the gsmtap packets sent over the network (i.e.,
non-localhost). There was no UDP listener on the receiving end, such
that ICMP port-unreachable replies were being sent back. It would
appear that this causes the sender's kernel to snub some of the
outgoing packets.  I don't know if the same happens on localhost.

If this is your case, you can try "iptables -I INPUT -p udp -d 4729 -j
DROP", or something like "nc -l -u 4729 > /dev/null".


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