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Re: Scanning (was Re: Stealth Blocking)
From: "Joseph T. Klein" <jtk () titania net>
Date: Thu, 24 May 2001 14:16:12 +0000

20% of Internet bandwidth utilization is from scanning ...
                                        -- Another made up statistic.


The elephant is getting hurt by the blind men.

How do I differentiate a "white hat" scan from a "black hat" scan?

I don't mind people like Bill Manning who send out polite notification
before scanning my DNS but general network scanning is starting to get

By my count the average random scans come at least 4 times a week.

What is the effect of scanning the whole operational address space
four times a week?

At 08:52 -0400 24-05-2001, William Allen Simpson wrote:
Actually, scanning is an important security tool.  It is also an
important network monitoring tool.

Over the years, we've used scanning to determine the density of IP
address assignment, in-addr propagation, and other operational issues.

Recently, the OpenSSH project has been doing random probes to determine
the numbers and versions of SSH, and sequential probes in selected
address space to warn operators of vulnerable early versions.

In general, scanning should be done regularly.  If not by the affected
network operator, then by the targets that have been contacted by the
affected network.

I _do_ accept that a connected Internet means that anybody may scan
anybody else's network.  In fact, it is a natural consequence.

There is nothing wrong with scanning.

(The problem with ORBS was not the scanning, but rather the aggressive
nature of the scanner, and the belligerence of the operator.  Denial of
service is a different kettle of fish.)

David Schwartz wrote:

 Jon Lewis wrote:

 > What's so bad about pre-emptive open-relay scanning?  What's the
 > difference between an open-relay found/used by a spammer and added to the
 > RSS and an open-relay found by pre-emptive scanner and added to the RSS?
 > Both sites are likely sources of relay spam.

What's so bad about pre-emptive open-relay scanning is that if you feel
 that is justified, you pretty much have accepted that anybody who pleases
 may scan anybody else's network for any weakness he or she would like to
 probe for. And if someone else probed 40,000 of your hosts each for 500
 vulnerabilitise, you would have to accept the probers answer that there's
 nothing wrong with pre-emptive scanning. After all, if someone else gets
 root on your system, it's a potential threat to him. I am not happy with
 that result.

Joseph T. Klein                                         +1 414 915 7489
Senior Network Engineer                                 jtk () titania net
Adelphia Business Solutions                joseph.klein () adelphiacom com

    "... the true value of the Internet is its connectedness ..."
                                                 -- John W. Stewart III

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