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Re: zotob - blocking tcp/445

  • From: Peter Dambier
  • Date: Thu Aug 18 14:05:26 2005

Roger Marquis wrote:
Andy Johnson wrote:

I think the point of many on this list is, they are a transit
provider, not a security provider. They should not need to filter
your traffic, that should be up to the end user/edge network to
decide for themselves.

How is this different from a transit provider allowing their network
to be used for spam?  Seems the same hands-off argument was made wrt
spam a decade ago but has since proved unsustainable.

Our particular problem is with an ISP in Wisconsin, NETNET-WAN.  We
get tens of thousands of scans to netbios ports every day from their
/19.  This is several orders of magnitude more netbios than we see

from the rest of the net combined.  It's eating nontrivial bandwidth
and cpu that we pay real money for.  They've had our logs for months
but seem incapable of doing anything about their infected customers.
The suits recommend documenting time and bandwidth costs and sending
a bill with a cease and desist request.

My question is not what can we do about bots, we already filter
these worst case networks, but what can we do to make it worthwhile
for bot-providers like NETNET to police their own networks without
involving lawyers?

Route them through a modem using 4800 Baud. They will very soon look
what is eating their bandwidth and hopefully find those netbios packets.

Blocking port 445 will prevent me from using "ssh -p 455" to reach my
clients. Using 4800 baud will slow me down but it will not stop me working.

Does anyone really use port 22 for ssh? I cannot use it because of all
those wordbook attacks. Nobody cares to stop those.

Peter and Karin Dambier

Peter and Karin Dambier
Graeffstrasse 14
D-64646 Heppenheim
+49-6252-671788 (Telekom)
+49-179-108-3978 (O2 Genion)
+49-6252-750308 (VoIP:
+1-360-448-1275 (VoIP:

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