Are botnets relevant to NANOG?

John Kristoff jtk at
Fri May 26 19:36:57 UTC 2006

On Fri, 26 May 2006 11:50:21 -0700
Rick Wesson <wessorh at> wrote:

> The longer answer is that we haven't found a reliable way to identify 
> dynamic blocks. Should anyone point me to an authoritative source I'd
> be happy to do the analysis and provide some graphs on how dynamic 
> addresses effect the numbers.

I don't know how effective the dynamic lists maintained by some in
the anti-spamming community is, you'd probably know better than I,
but that is one way as decribed in the paper.  In the first section
of the paper I cited they lists three methods they used to try to
capture stable IP addresses.  Summarizing those:

  1. reverse map the IP address and analyze the hostname
  2. do same for nearby addresses and analyze character difference ratio
  3. compare active probes of suspect app with icmp echo response

None of these will be foolproof and the last one will probably only
be good for cases where there is a service running where'd you'd
rather there not be and you can test for it (e.g. open relays).

There was at least one additional reference to related work in that
paper, which leads to more still, but I'll let those interested to
do their own research on additional ideas for themselves.

> also note that we are using TCP fingerprinting in our spamtraps and 
> expect to have some interesting results published in the august/sept 
> time frame. We won't be able to say that a block is dynamic but we
> will be able to better understand if we talk to the same spammer from 
> different ip addresses and how often those addresses change.

Will look forward to seeing more.  Thanks,


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