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Date:      Mon, 8 Jul 2002 16:18:08 -0700
From:      "Philip J. Koenig" <pjklist@ekahuna.com>
To:        security@FreeBSD.ORG
Subject:   Re: hiding OS name
Message-ID:  <20020708231809505.AAA981@empty1.ekahuna.com@pc02.ekahuna.com>
In-Reply-To: <bulk.35441.20020708074200@hub.freebsd.org>

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> Date: Sun, 7 Jul 2002 21:29:42 -0700
> From: Nathan Kinkade <nkinkade@dsl-only.com>
> 
> On Mon, 8 Jul 2002 09:32:09 +0700
> "Asep Ruspeni" <ruspeni@mti.itb.ac.id> wrote:
> 
> > I am newbie in FreeBSD OS, but i have lot of concerned in securing
> > system.
> > 
> > I have questions like this :
> > 
> > - how can i set-up FreeBSD, so when it being scanned, it's show no
> > operating system name + version.
> > - is there any articles i colud read about securing freeBSD such as
> > the question i ask above.
> > 
> > thank you in advance.
> 
> What you are looking for is not really a function of FreeBSD, but rather
> of the various servers you may be running on FreeBSD such as Apache,
> FTP, Sendmail, and so on.  If it's going to happen it will probably be
> something that you configure the daemon to do, however I don't know
> which allow you to do something similar other than wu-ftpd, although I'd
> guess there are others.  Network scanning utilities - I'm thinking of
> nmap in particular - allow you to scan a host(s) and attempt to
> determine the OS/version based on certain peculiarities in the
> response(s).  One way to help minimize the impact of this would be to
> set the net.inet.tcp.blackhole and net.inet.udp.blackhole kernel
> parameters using the sysctl utility.  For more information on this
> checkout the "blackhole(4)" manpage with `man 4 blackhole`.
> 
> Nathan


Another option is to put the box behind a firewall.  Very often if 
something like nmap is looking for peculiarities in the IP stack 
implementation to ascertain what OS is on a box, if there is a 
firewall in front of it it will be id'ing the firewall's IP 
implementation rather than the target host's.



--
Philip J. Koenig                                       pjklist@ekahuna.com
Electric Kahuna Systems -- Computers & Communications for the New Millenium


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