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Date:      Fri, 14 Nov 2008 13:42:33 -0500
From:      Robert Noland <rnoland@FreeBSD.org>
To:        Julian Elischer <julian@elischer.org>
Cc:        sclark46@earthlink.net, FreeBSD Stable <freebsd-stable@freebsd.org>, freebsd-net@freebsd.org
Subject:   Re: FreeBSD 6.3 gre and traceroute
Message-ID:  <1226688153.1719.23.camel@squirrel.corp.cox.com>
In-Reply-To: <491DC28E.80804@elischer.org>
References:  <491B2703.4080707@earthlink.net>	<491B31F7.30200@elischer.org> <491B4345.80106@earthlink.net>	<491B47D2.6010804@elischer.org> <491C2235.4090509@earthlink.net> <1226589468.1976.12.camel@wombat.2hip.net> <491C4EC2.2000802@earthlink.net> <491D6CED.50006@earthlink.net> <491DC28E.80804@elischer.org>

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On Fri, 2008-11-14 at 10:25 -0800, Julian Elischer wrote:
> Stephen Clark wrote:
> > Stephen Clark wrote:
>=20
> >>>>>
> >>>>> 10.0.129.1 FreeBSD workstation
> >>>>>  ^
> >>>>>  |
> >>>>>  | ethernet
> >>>>>  |
> >>>>>  v
> >>>>> 10.0.128.1 Freebsd FW "A"
> >>>>>  ^
> >>>>>  |
> >>>>>  | gre / ipsec
> >>>>>  |
> >>>>>  v
> >>>>> 192.168.3.1 FreeBSD FW "B"
> >>>>>  ^
> >>>>>  |
> >>>>>  | ethernet
> >>>>>  |
> >>>>>  v
> >>>>> 192.168.3.86 linux workstation
> >>>>>
>=20
> >> Also just using gre's without the=20
> >> underlying ipsec tunnels seems to
> >> work properly.
>=20
>=20
> This is the crux of the matter.
> IPSEC happens INSIDE the IP stack. The IP stack is responsible for
> the ICMP generation so it is much more likely that there is an=20
> interaction there.
>=20
> Now is there an IPSEC rule to make sure that the ICMP packet can get=20
> back?  It could b ehtat in teh IP stack there is some confusion as to=20
> whether the return packet should be encrypted or not and it might get=20
> dropped.
>=20
> the code involved is in /sys/netinet and /sys/netipsec but you'll
> probably regret looking in there ;-)

Right, I don't really know the IPSEC code, but I was told by someone who
is familiar with it that this is a known problem and that the use of GRE
is not relevant.  Hopefully he will have a moment to respond to this
thread with a bit more detail.

robert.

>=20
>=20
> >>
> >>
> > Another data point I had been using option FILTER_GIF I tried a kernel
> > without that option and it behaved the same.
> >=20
> > Steve
> >=20
>=20

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