Default route (IPv4) demolished by destroying clone (gif/gre) interface

[Yar Tikhiy]

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().

-- 
Yar