Date: Wed, 16 Aug 2006 15:59:13 -0500 From: Brooks Davis <brooks@one-eyed-alien.net> To: Andrew Thompson <thompsa@freebsd.org> Cc: Yar Tikhiy <yar@comp.chem.msu.su>, freebsd-stable@freebsd.org, Stefan Bethke <stb@lassitu.de>, drl@MyBSD.org.my Subject: Re: Default route (IPv4) demolished by destroying clone (gif/gre) interface Message-ID: <20060816205913.GA69877@lor.one-eyed-alien.net> In-Reply-To: <20060816204927.GA73369@heff.fud.org.nz> References: <20060815040736.2f85f090.drl@MyBSD.org.my> <9405D801-3435-419A-9541-E1A9B2CF26D2@lassitu.de> <20060816081130.GB81271@comp.chem.msu.su> <FED9705F-B445-4495-B90F-A656AAA966EE@lassitu.de> <20060816145419.GB62485@lor.one-eyed-alien.net> <20060816155844.GA85503@comp.chem.msu.su> <20060816171524.GA63928@lor.one-eyed-alien.net> <20060816204927.GA73369@heff.fud.org.nz>
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On Thu, Aug 17, 2006 at 08:49:27AM +1200, Andrew Thompson wrote:
> On Wed, Aug 16, 2006 at 12:15:25PM -0500, Brooks Davis wrote:
> > On Wed, Aug 16, 2006 at 07:58:44PM +0400, Yar Tikhiy wrote:
> > > On Wed, Aug 16, 2006 at 09:54:19AM -0500, Brooks Davis wrote:
> > > > On Wed, Aug 16, 2006 at 10:23:13AM +0200, Stefan Bethke wrote:
> > > > >=20
> > > > > Ouch. Don't ppp(8), OpenVPN etc. destroy the tun interface they'r=
e =20
> > > > > using when they exit? Flushing all routes then would be rather =
=20
> > > > > harmful. I'm glad I haven't updated to a newer -stable yet then =
:-)
> > > >=20
> > > > In general, no since tun interfaces can not be destroyed.
> > >=20
> > > Did you mean "in particular"? :-)
> > >=20
> > > The problem can be triggered by destroying any interface that can
> > > be destroyed. Just imagine getting rid of a defunct gif tunnel on
> > > a remote router, or removing an unused vlan, and totally losing
> > > connectivity to the router due to its default route having been
> > > flushed. The scenario still can be quite unpleasant. I'd rather
> > > change the default for $removable_route_flush to NO and let the
> > > kernel choose which routes should be flushed upon the physical
> > > ejection or software destruction of an interface. Note that this
> > > doesn't include static_routes_${ifn}, which are handled separately
> > > by pccard_ether_stop().
> >=20
> > Agreed. That code shouldn't be on by default. I've disabled in it HEAD
> > and will MFC in a few days. As another poster said, I'm not even sure
> > it should exist as an option.
>=20
> Thanks for fixing this up, it certainly was odd to be flushing routes in
> userland. I have one more bug report from the ifnet/devd change to look
> at where renamed interfaces give some sort of an error.
It is a rather weird bit of code. It deletes all IPv4 routes on exit.
I suspect it's a hack left over from before interface removal really
worked. I may just delete the code in HEAD after the MFC. I think we
could also remove the arp flush or move it into "netif stop" and narrow
it with the -i option.
-- Brooks
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