From owner-freebsd-security@FreeBSD.ORG  Wed Jul  6 05:39:19 2005
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To: Jesper Wallin <jesper@hackunite.net>
References: <200507051428.j65ESjJu001522@caligula.anu.edu.au>
	<42CAA478.7010806@hackunite.net>
From: des@des.no (=?iso-8859-1?q?Dag-Erling_Sm=F8rgrav?=)
Date: Wed, 06 Jul 2005 07:39:13 +0200
In-Reply-To: <42CAA478.7010806@hackunite.net> (Jesper Wallin's message of
	"Tue, 05 Jul 2005 17:17:12 +0200")
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Cc: freebsd-security@freebsd.org, Darren Reed <avalon@caligula.anu.edu.au>
Subject: Re: packets with syn/fin vs pf_norm.c
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Jesper Wallin <jesper@hackunite.net> writes:
> Also, I wonder why the TCP_DROP_SYNFIN option isn't checked in pf_norm.c?

Because there's no reason for it to be.

> Sure, it might be bad/good/whatever dropping packets with SYN/FIN,
> but if you decide to do it and add the TCP_DROP_SYNFIN option, then
> it should drop them even if you use pf, ipf or ipfw..

No.  If you want to drop SYN+FIN frames that pass *through* you (as
opposed to those sent *to* you), it's easy enough to add a firewall
rule.

The TCP_DROP_SYNFIN option should be removed; it has long outlived its
original purpose (which was to prevent nmap identification of IRC
servers which didn't run ipfw for performance reasons, back in the 3.0
days)

DES
--=20
Dag-Erling Sm=F8rgrav - des@des.no