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Date:      Wed, 31 Oct 2001 14:36:33 +0100
From:      Mipam <mipam@ibb.net>
To:        Michael Scheidell <scheidell@fdma.com>
Cc:        freebsd-security@FreeBSD.ORG
Subject:   Re: can I use keep-state for icmp rules?
Message-ID:  <20011031143633.E397@ibb1150.ibb.uu.nl>
In-Reply-To: <000901c1620f$51428530$2801010a@MIKELT>; from scheidell@fdma.com on Wed, Oct 31, 2001 at 08:24:05AM -0500
References:  <009c01c16017$dca045d0$0603a8c0@MIKELT> <20011029153954.B224@gohan.cjclark.org> <005501c1613f$dfb46520$0603a8c0@MIKELT> <20011030164253.C223@gohan.cjclark.org> <000901c1620f$51428530$2801010a@MIKELT>

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> >                    TCP
> >   src_ip.src_port ----> dst_ip.dst_port
> >
> > I can send _any_ TCP packet back,
> >
> >                    TCP
> >   src_ip.src_port <---- dst_ip.dst_port
> >
> > And it will pass provided the source and destination IP and ports all
> > line up. ipfw(8) does not consider the TCP flags, sequence number,

Bit off topic, but nowadays still a lot of so called 'best' and great
commercial firewalls still dont check the sequence number for example.
Would be good enough for udp state keeping in a way,
but not for tcp. Not to mention icmp statekeeping which still
isn't possible in many products.

Mipam.

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