[rescue] What is this traffic?

Yvan Janssens ik at yvanj.me
Thu Oct 29 07:27:40 CDT 2015

Do you have any form of IPTV from your DSL provider?

I have seen this type of behaviour on locations where the DSL provider also
provided IPTV over UDP multicasts, combined with cheaper switches which
don't properly filter out the streams a machine didn't subscribe to.


On Thu, Oct 29, 2015 at 1:24 PM <microcode at zoho.com> wrote:

> On Thu, Oct 29, 2015 at 12:54:27PM +0100, Jonathan Katz wrote:
> > On Thu, Oct 29, 2015 at 12:45 PM,  <microcode at zoho.com> wrote:
> > > I have no evidence of anything getting to any of the boxes on my LAN.
> iptraf
> > >
> > > Is there any way to see what the traffic between the router and the
> switch
> > > is without extra equipment? Does anybody have any idea what this could
> be?
> >
> > The extra equipment part is difficult. If you're willing to sacrifice
> > network performance in the short-term dust off an old 10Mbit hub in
> > the closet and put that between the ADSL router and the switch and
> > then run snoop or tcpdump on something plugged into the hub.
> I don't have any other switches or hubs. I'm really hurting for equipment.
> The network performance I am getting is so bad I don't think sacrificing it
> is a possibility! I am paying for 15Mb/s and getting 1.5M on a good day.
> For
> about two years it was fine and then for the last two it has gotten worse
> and worse. It's a blame game between the carrier and the ISP and although I
> am sure it's the ISP I can't get them to fix it. There are very few
> providers and it's not clear switching would help although I will anyway
> shortly I hope.
> > How dumb is your TP-Link switch? Could it take dd-wrt or similar? That
> > could allow you to mirror the interface between the switch and the
> > ADSL router and you can snoop traffic that way.
> Ah, no, it's an unmanagemed switch and not user flashable as far as I
> know. There is no management interface and nothing but RJ-45 ports.
> > Alternately, does it happen at a set interval? Like every "N" hours
> > after the ADSL modem has been rebooted? I'm wondering if it is some
> > kind of standard ARP broadcast/mapping that is going on as a part of
> > spanning tree. Like the ADSL port keeps a cache of the MAC addresses
> > that it expects to find beyond the switch port it is plugged into.
> The light goes crazy whenever the switch is connected to the router. I have
> not seen anything that gives me any clues apart from that. The light is
> flashing at a high rate all the time, regardless of traffic from any of the
> boxes on my network.
> Thanks.
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This message has been sent on the road - excuse me for my brevity.

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