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Message-ID: <38F465BE.ABD322C@elischer.org>
Date: Wed, 12 Apr 2000 05:02:06 -0700
From: Julian Elischer <julian@elischer.org>
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To: Ruslan Ermilov <ru@ucb.crimea.ua>
Cc: net@FreeBSD.ORG, archie@wistle.com, brian@FreeBSD.ORG,
	Dru Nelson <dnelson@redwoodsoft.com>
Subject: Re: pptp over NAT? Impossible?
References: <38F43C84.3F54BC7E@elischer.org> <20000412125131.A8975@relay.ucb.crimea.ua> <20000412132221.A14970@relay.ucb.crimea.ua>
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Ruslan Ermilov wrote:
> 
> On Wed, Apr 12, 2000 at 12:51:31PM +0300, Ruslan Ermilov wrote:
> > On Wed, Apr 12, 2000 at 02:06:12AM -0700, Julian Elischer wrote:
> > > I've been beeting my head against a problem that I think
> > > I suddenly understand..
> > > I've been trying to run a pptp session out from an address translated
> > > network (i.e. ppp -nat). It gets so far tand then stops.
> > > It has suddenly (after a day wasted) occured to me that
> > > maybe the ppp negotiation is being carried by GRE and that
> > > I'm guessing that GRE is not translatable.. (At least by
> > > ppp -nat). (what's happenning is that the ppp negotiating packets are
> > > getting lost in transit.)
> > >
> > GRE is supported in different way, see `nat pptp [addr]' in ppp(8),
> > and PacketAliasPptp() in libalias(3).
> >
> By the way, I see no reason why PPTP support is limited to only
> one local IP address.  It *is* possible to improve PPTP support
> by introducing the following interface:
> 
> int PacketAliasPptp(
>         struct in_addr local_addr,
>         struct in_addr remote_addr,
>         struct in_addr alias_addr
> );
> 
> where `local_addr', `alias_addr'  and `remote_addr' are of the same
> semantics as in PacketAliasRedirectPort() (see libalias(3) manpage).
> 
> If Brian does not mind, I will implement this, then patch natd(8),
> wait until Brian prepares patches for ppp(8), commit the change to
> libalias(3), bump library's major number, and commit the rest to
> natd(8) and ppp(8).
> 
> Comments?

Makes sence to me as it is quite possible that GRE/PPTP could be
coming from several different internal machines.

BTW shouldn't this be called PacketAliasGRE instead?

> 
> --
> Ruslan Ermilov          Sysadmin and DBA of the
> ru@ucb.crimea.ua        United Commercial Bank,
> ru@FreeBSD.org          FreeBSD committer,
> +380.652.247.647        Simferopol, Ukraine
> 
> http://www.FreeBSD.org  The Power To Serve
> http://www.oracle.com   Enabling The Information Age

-- 
      __--_|\  Julian Elischer
     /       \ julian@elischer.org
    (   OZ    ) World tour 2000
---> X_.---._/  presently in:  Perth
            v


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