Re: "portscans" (was Re: Arbor Networks DoS defense product)

[Scott Francis <darkuncle () darkuncle net>]

On Sat, May 18, 2002 at 09:43:16PM -0400, sgifford () suspectclass com said:
[snip]
> > network to gather information or run recon if they were not planning on
> > attacking? I'm not saying that you're not right, I'm just saying that so far
> > I have heard no valid non-attack reasons for portscans (other than those run
> > by network admins against their own networks).
>
> Before choosing an onling bank, I portscanned the networks of the
> banks I was considering.  It was the only way I could find to get a
> rough assessment of their network security, which was important to me
> as a customer for obvious reasons.

In that case, I would not consider the scan to have come from an
'unaffiliated' person. I'm sure if the bank's network operator noticed it,
and contacted you, things would have been cleared up with no harm done. To
make it a bit more clear: cases where the scanner can demonstrate a good and
benign reason for scanning (they do occasionally exist[1]), no blackhole is
required. Sending an email notification prior to putting in a blackhole is a
good first step to eliminate potential false positives.

[1] Random strangers unaffiliated with your network will almost never have a
valid & benign reason for portscanning you.

> I'm not sure if I would have been impressed or annoyed if they had
> stopped accepting packets from my machine during the scan.  :-)

Loss of a customer, probably. :)

-- 
Scott Francis                   darkuncle@ [home:] d a r k u n c l e . n e t
Systems/Network Manager          sfrancis@ [work:]         t o n o s . c o m
GPG public key 0xCB33CCA7              illum oportet crescere me autem minui

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