Default route (IPv4) demolished by destroying clone (gif/gre)
interface
Brooks Davis
brooks at one-eyed-alien.net
Wed Aug 16 20:59:35 UTC 2006
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:
> > > > >
> > > > > Ouch. Don't ppp(8), OpenVPN etc. destroy the tun interface they're
> > > > > using when they exit? Flushing all routes then would be rather
> > > > > harmful. I'm glad I haven't updated to a newer -stable yet then :-)
> > > >
> > > > In general, no since tun interfaces can not be destroyed.
> > >
> > > Did you mean "in particular"? :-)
> > >
> > > 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().
> >
> > 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.
>
> 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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