From owner-freebsd-security  Thu Mar 28 12:40: 1 2002
Delivered-To: freebsd-security@freebsd.org
Received: from pumaman.dyndns.org (rm059.isis.de [195.158.147.59])
	by hub.freebsd.org (Postfix) with ESMTP id BD36137B419
	for <freebsd-security@freebsd.org>; Thu, 28 Mar 2002 12:39:54 -0800 (PST)
Received: from ws.bnet ([192.168.100.222] helo=there)
	by pumaman.dyndns.org with smtp (Exim 3.34 #1)
	id 16qggb-000Ndz-00; Thu, 28 Mar 2002 21:39:53 +0100
Content-Type: text/plain;
  charset="iso-8859-1"
From: Bjoern Engels <bjoern.engels@mail.isis.de>
To: freebsd-security@freebsd.org, Moti Levy <moti@flncs.com>
Subject: Re: How can I erase my fingertips .
Date: Thu, 28 Mar 2002 21:39:51 +0100
X-Mailer: KMail [version 1.3.2]
References: <20020328172259.C73793-100000@cianet.cianet.ind.br>
In-Reply-To: <20020328172259.C73793-100000@cianet.cianet.ind.br>
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Message-Id: <E16qggb-000Ndz-00@pumaman.dyndns.org>
Sender: owner-freebsd-security@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-security.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-security>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-security>
X-Loop: FreeBSD.org

On Thursday, 28. March 2002 21:25, Alvaro Pereira wrote:

> On Thu, 28 Mar 2002, Moti Levy wrote:
> > I want to stop nmap from detecting my os .

> from /usr/src/sys/i386/conf/LINT
>
> #
> # TCP_DROP_SYNFIN adds support for ignoring TCP packets with SYN+FIN.
> This # prevents nmap et al. from identifying the TCP/IP stack, but
> breaks support # for RFC1644 extensions and is not recommended for
> web servers. #
> options         TCP_DROP_SYNFIN         #drop TCP packets with
> SYN+FIN
>

Additionally, add

# RANDOM_IP_ID causes the ID field in IP packets to be randomized
options         RANDOM_IP_ID

and change the default TTL.

Bjoern

--=20

"The number of Unix installations has grown to ten, with more expected"
                -- The Unix programmers handbook, 1972

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-security" in the body of the message