Subject: Re: What is the gre pseudo-device? Wjy would it make PPTP break?
To: Martin Husemann <>
From: Quentin Garnier <>
List: current-users
Date: 08/04/2002 15:25:35
On Sun, Aug 04, 2002 at 11:24:16AM +0200, Martin Husemann wrote:
> On Fri, Jul 19, 2002 at 11:38:09PM +0200, cube wrote:
> > PoPToP could create and use a gre interface and let the kernel manage the
> > encapsulation, which would require the compilation of gre into the kernel.
> The pkg should be changed to try this (it is far superior from a perfomance
> point of view) and only fall back to the (current) userland way if the ioctl
> creating the gre interface fails (i.e. no "pseudo-device gre" is compiled
> into the kernel).

It is slighty more complicated, in fact. The gre(4) pseudo-device of NetBSD
only implements IP-over-IP, although PoPToP uses another protocol on top of

So we have to implement the PPTP_GRE protocol into the kernel to make PoPToP
or find a way to make PoPToP uses its own code while gre(4) is compiled.

Implemeting the ad-hoc protocol in the kernel shouldn't be too hard, but
the userland interface (ioctls and greconfig(8)) seem to be quite dedicated
to IP-over-IP tunneling.