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Date:      Thu, 15 May 2003 19:00:57 +0100
From:      "G D McKee" <freebsd@gdmckee.com>
To:        <freebsd-questions@freebsd.org>
Subject:   Securing FreeBSD
Message-ID:  <001001c31b0b$efe77720$c700a8c0@p2000>

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Hi all

I am trying to secure my freebsd box and avoid giving to much info away =
to port scans.

I have found some site relating to this and have put the following lines =
in /etc/sysctl.conf

net.inet.tcp.blackhole=3D2
net.inet.udp.blackhole=3D1

and added these to the firewall:

options         RANDOM_IP_ID
options         TCP_DROP_SYNFIN         #drop TCP packets with SYN+FIN

Can someone explain to me why the TCP_DROP_SYNFIN option breaks web =
access?  It doesn't seem to have made any changes that I have noticed.  =
I can't find any docs regarding this to explain what it might break.  =
Does anyone know any other variables to add to make me more secure?

Thanks in advance

Gordon



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