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Date:      Fri, 06 Mar 1998 23:54:35 -0600
From:      Kris Kirby <kris@ninbox.ml.org>
To:        David Babler <root@Rigel.orionsys.com>
Cc:        freebsd-isp@FreeBSD.ORG
Subject:   Re: Port 137 access - somebody monkeying around?
Message-ID:  <3500E11B.ACD322CF@ninbox.ml.org>
References:  <Pine.BSF.3.96.980306132649.6827G-100000@Rigel.orionsys.com>

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David Babler wrote:

> My ipfw rules deny and log all services that I don't support here, and
> I've noticed that I will often see a string of access attempts on my port
> 137 (NetBIOS Name Service) from foreign addresses (not once from any of my
> dialup customers). I was under the impression that these contacts might be
> Bad Guys trying to take advantage of some known exploit, thinking I was
> running NT or something. Is that a valid assumption, or is there some
> legitimate reason why foreign IPs should be trying to connect to that
> port? I complained once to a system one of whose dialup customers
> continued a port 137 probe on and off for an hour. When the user was
> contacted, he claimed he had NO IDEA what we were talking about, that he
> might have just "tried something" with a browser.

My question is this: Why are you worried about rejects? I'd make your
alarms go off if I piped "QUIT" throught Netcat. What you should worry
about is if they can get by the rules. 
 
> Am I being too paranoid?

H-E-L-K No. You can never be too paranoid about security. 

-- 

Kris Kirby <kris@airnet.net>
-------------------------------------------
TGIFreeBSD... 'Nuff said.

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