Date: Thu, 15 Jan 2004 15:47:34 -0500 From: "Michael W. Oliver" <michael@gargantuan.com> To: Robert Watson <rwatson@freebsd.org> Cc: Vlad Galu <dudu@diaspar.rdsnet.ro> Subject: Re: Dummy Network Interface Message-ID: <20040115204734.GA61637@gargantuan.com> In-Reply-To: <Pine.NEB.3.96L.1040115150648.74950A-100000@fledge.watson.org> References: <20040115053524.2c6e8db2.dudu@diaspar.rdsnet.ro> <Pine.NEB.3.96L.1040115150648.74950A-100000@fledge.watson.org>
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On Thu, Jan 15, 2004 at 03:07:20PM -0500, Robert Watson wrote:
>=20
> On Thu, 15 Jan 2004, Vlad Galu wrote:
>=20
> > |On Tue, 13 Jan 2004 ms419@freezone.co.uk wrote:
> > |
> > |> How does one create a dummy network interface in FreeBSD?=20
> > |
> > |Dummy in what sense? An interface where the packets are simply
> > |dropped? if_tap and if_tun both provide pseudo-device in /dev that a
> > |userspace process can attach to in order to emulate a network interface
> > |(used by VMWare, ppp, various tunneling bits, ...) In the absense of a
> > |process sitting on the device, they simply drop the packets. Although
> > |they may get garbage-collected if unused on -CURRENT... You can also
> > |use netgraph to bring pseudo-interfaces, perhaps without anywhere for
> > |packets to go.=20
> > |
> > |And, I suppose, create in what sense? Are you looking at this from a
> > |developer perspective, or you just need one from a user perspective.=
=20
> > |If writing a device driver (and hence needing a starting point), if_tap
> > |and if_tun are fairly decent models for a pseudo-interface.
> >=20
> > I think he could use the discard interface smoothly. On Linux
> > (from which the dummy interface notion is taken from) it is simply used
> > for testing purposes, as in routing, or perhaps socket programming. I
> > personally have used it for a while, but then I used interface aliasing,
> > which became a habit.=20
>=20
> Does the discard interface in Linux "act like" another type of interface,
> such as point-to-point, ethernet, etc?=20
I believe that he was referring to the discard interface in FreeBSD. I
don't know about Linux at all, but I have used the discard interface in
a FreeBSD router much like a Null interface in a cisco router.
pseudo-device disc
man 4 disc
--=20
Mike
perl -e 'print unpack("u","88V]N=3D&%C=3D\"!I;F9O(&EN(&AE861E<G,*");'
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